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WSU Vancouver - Engineering amp Computer Science WSU Vancouver - Engineering amp Computer Science
CS558 Advanced Topics in CS558 Advanced Topics in Wireless NetworksWireless Networks
Dr Wenzhan Song
Assistant Professor Computer Science
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
2
Ethernet uses CSMACDEthernet uses CSMACD
No slots adapter doesnrsquot transmit if it
senses that some other adapter is transmitting that is carrier sense
transmitting adapter aborts when it senses that another adapter is transmitting that is collision detection
Before attempting a retransmission adapter waits a random time that is random access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
3
CSMACD (Collision CSMACD (Collision Detection)Detection)
CSMACD carrier sensing deferral as in CSMA collisions detected within short time colliding transmissions aborted reducing channel wastage
collision detection easy in wired LANs measure signal strengths compare
transmitted received signals difficult in wireless LANs receiver shut off while transmitting
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
4
Ethernet CSMACD algorithmEthernet CSMACD algorithm1 Adaptor receives datagram
from net layer amp creates frame
2 If adapter senses channel idle it starts to transmit frame If it senses channel busy waits until channel idle and then transmits
3 If adapter transmits entire frame without detecting another transmission the adapter is done with frame
4 If adapter detects another transmission while transmitting aborts and sends jam signal
5 After aborting adapter enters exponential backoff after the mth collision adapter chooses a K at random from 012hellip2m-1 Adapter waits K512 bit times and returns to Step 2
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
5
Ethernetrsquos CSMACD (more)Ethernetrsquos CSMACD (more)
Jam Signal make sure all other transmitters are aware of collision 48 bits
Bit time 1 microsec for 10 Mbps Ethernet for K=1023 wait time is about 50 msec
Exponential Backoff Goal adapt retransmission
attempts to estimated current load
heavy load random wait will be longer
first collision choose K from 01 delay is K 512 bit transmission times
after second collision choose K from 0123hellip
after ten collisions choose K from 01234hellip1023
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
6
CSMACD (Collision CSMACD (Collision Detection)Detection)
CSMACD can be in one of three states contention transmission or idle
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
7
CSMACD efficiencyCSMACD efficiency
See equation on textbook page 280 Much better than ALOHA also
decentralized simple and cheap
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
8
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless hosts laptop PDA IP phone run applications may be stationary
(non-mobile) or mobile
wireless does not always mean mobility
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
9
Elements of a wireless networkElements of a wireless network
network infrastructure
base station typically connected
to wired network relay - responsible
for sending packets between wired network and wireless host(s) in its ldquoareardquo
eg cell towers 80211 access points
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
10
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless link typically used to
connect mobile(s) to base station
also used as backbone link
multiple access protocol coordinates link access
various data rates transmission distance
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
11
Elements of a wireless networkElements of a wireless network
network infrastructure
infrastructure mode base station
connects mobiles into wired network
handoff mobile changes base station providing connection into wired network
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
12
Elements of a wireless networkElements of a wireless network
Ad hoc mode no base stations nodes can only
transmit to other nodes within link coverage
nodes organize themselves into a network route among themselves
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
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27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
2
Ethernet uses CSMACDEthernet uses CSMACD
No slots adapter doesnrsquot transmit if it
senses that some other adapter is transmitting that is carrier sense
transmitting adapter aborts when it senses that another adapter is transmitting that is collision detection
Before attempting a retransmission adapter waits a random time that is random access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
3
CSMACD (Collision CSMACD (Collision Detection)Detection)
CSMACD carrier sensing deferral as in CSMA collisions detected within short time colliding transmissions aborted reducing channel wastage
collision detection easy in wired LANs measure signal strengths compare
transmitted received signals difficult in wireless LANs receiver shut off while transmitting
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
4
Ethernet CSMACD algorithmEthernet CSMACD algorithm1 Adaptor receives datagram
from net layer amp creates frame
2 If adapter senses channel idle it starts to transmit frame If it senses channel busy waits until channel idle and then transmits
3 If adapter transmits entire frame without detecting another transmission the adapter is done with frame
4 If adapter detects another transmission while transmitting aborts and sends jam signal
5 After aborting adapter enters exponential backoff after the mth collision adapter chooses a K at random from 012hellip2m-1 Adapter waits K512 bit times and returns to Step 2
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
5
Ethernetrsquos CSMACD (more)Ethernetrsquos CSMACD (more)
Jam Signal make sure all other transmitters are aware of collision 48 bits
Bit time 1 microsec for 10 Mbps Ethernet for K=1023 wait time is about 50 msec
Exponential Backoff Goal adapt retransmission
attempts to estimated current load
heavy load random wait will be longer
first collision choose K from 01 delay is K 512 bit transmission times
after second collision choose K from 0123hellip
after ten collisions choose K from 01234hellip1023
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
6
CSMACD (Collision CSMACD (Collision Detection)Detection)
CSMACD can be in one of three states contention transmission or idle
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
7
CSMACD efficiencyCSMACD efficiency
See equation on textbook page 280 Much better than ALOHA also
decentralized simple and cheap
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
8
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless hosts laptop PDA IP phone run applications may be stationary
(non-mobile) or mobile
wireless does not always mean mobility
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
9
Elements of a wireless networkElements of a wireless network
network infrastructure
base station typically connected
to wired network relay - responsible
for sending packets between wired network and wireless host(s) in its ldquoareardquo
eg cell towers 80211 access points
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
10
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless link typically used to
connect mobile(s) to base station
also used as backbone link
multiple access protocol coordinates link access
various data rates transmission distance
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
11
Elements of a wireless networkElements of a wireless network
network infrastructure
infrastructure mode base station
connects mobiles into wired network
handoff mobile changes base station providing connection into wired network
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
12
Elements of a wireless networkElements of a wireless network
Ad hoc mode no base stations nodes can only
transmit to other nodes within link coverage
nodes organize themselves into a network route among themselves
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
3
CSMACD (Collision CSMACD (Collision Detection)Detection)
CSMACD carrier sensing deferral as in CSMA collisions detected within short time colliding transmissions aborted reducing channel wastage
collision detection easy in wired LANs measure signal strengths compare
transmitted received signals difficult in wireless LANs receiver shut off while transmitting
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
4
Ethernet CSMACD algorithmEthernet CSMACD algorithm1 Adaptor receives datagram
from net layer amp creates frame
2 If adapter senses channel idle it starts to transmit frame If it senses channel busy waits until channel idle and then transmits
3 If adapter transmits entire frame without detecting another transmission the adapter is done with frame
4 If adapter detects another transmission while transmitting aborts and sends jam signal
5 After aborting adapter enters exponential backoff after the mth collision adapter chooses a K at random from 012hellip2m-1 Adapter waits K512 bit times and returns to Step 2
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
5
Ethernetrsquos CSMACD (more)Ethernetrsquos CSMACD (more)
Jam Signal make sure all other transmitters are aware of collision 48 bits
Bit time 1 microsec for 10 Mbps Ethernet for K=1023 wait time is about 50 msec
Exponential Backoff Goal adapt retransmission
attempts to estimated current load
heavy load random wait will be longer
first collision choose K from 01 delay is K 512 bit transmission times
after second collision choose K from 0123hellip
after ten collisions choose K from 01234hellip1023
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
6
CSMACD (Collision CSMACD (Collision Detection)Detection)
CSMACD can be in one of three states contention transmission or idle
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
7
CSMACD efficiencyCSMACD efficiency
See equation on textbook page 280 Much better than ALOHA also
decentralized simple and cheap
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
8
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless hosts laptop PDA IP phone run applications may be stationary
(non-mobile) or mobile
wireless does not always mean mobility
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
9
Elements of a wireless networkElements of a wireless network
network infrastructure
base station typically connected
to wired network relay - responsible
for sending packets between wired network and wireless host(s) in its ldquoareardquo
eg cell towers 80211 access points
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
10
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless link typically used to
connect mobile(s) to base station
also used as backbone link
multiple access protocol coordinates link access
various data rates transmission distance
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
11
Elements of a wireless networkElements of a wireless network
network infrastructure
infrastructure mode base station
connects mobiles into wired network
handoff mobile changes base station providing connection into wired network
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
12
Elements of a wireless networkElements of a wireless network
Ad hoc mode no base stations nodes can only
transmit to other nodes within link coverage
nodes organize themselves into a network route among themselves
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
4
Ethernet CSMACD algorithmEthernet CSMACD algorithm1 Adaptor receives datagram
from net layer amp creates frame
2 If adapter senses channel idle it starts to transmit frame If it senses channel busy waits until channel idle and then transmits
3 If adapter transmits entire frame without detecting another transmission the adapter is done with frame
4 If adapter detects another transmission while transmitting aborts and sends jam signal
5 After aborting adapter enters exponential backoff after the mth collision adapter chooses a K at random from 012hellip2m-1 Adapter waits K512 bit times and returns to Step 2
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
5
Ethernetrsquos CSMACD (more)Ethernetrsquos CSMACD (more)
Jam Signal make sure all other transmitters are aware of collision 48 bits
Bit time 1 microsec for 10 Mbps Ethernet for K=1023 wait time is about 50 msec
Exponential Backoff Goal adapt retransmission
attempts to estimated current load
heavy load random wait will be longer
first collision choose K from 01 delay is K 512 bit transmission times
after second collision choose K from 0123hellip
after ten collisions choose K from 01234hellip1023
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
6
CSMACD (Collision CSMACD (Collision Detection)Detection)
CSMACD can be in one of three states contention transmission or idle
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
7
CSMACD efficiencyCSMACD efficiency
See equation on textbook page 280 Much better than ALOHA also
decentralized simple and cheap
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
8
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless hosts laptop PDA IP phone run applications may be stationary
(non-mobile) or mobile
wireless does not always mean mobility
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
9
Elements of a wireless networkElements of a wireless network
network infrastructure
base station typically connected
to wired network relay - responsible
for sending packets between wired network and wireless host(s) in its ldquoareardquo
eg cell towers 80211 access points
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
10
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless link typically used to
connect mobile(s) to base station
also used as backbone link
multiple access protocol coordinates link access
various data rates transmission distance
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
11
Elements of a wireless networkElements of a wireless network
network infrastructure
infrastructure mode base station
connects mobiles into wired network
handoff mobile changes base station providing connection into wired network
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
12
Elements of a wireless networkElements of a wireless network
Ad hoc mode no base stations nodes can only
transmit to other nodes within link coverage
nodes organize themselves into a network route among themselves
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
5
Ethernetrsquos CSMACD (more)Ethernetrsquos CSMACD (more)
Jam Signal make sure all other transmitters are aware of collision 48 bits
Bit time 1 microsec for 10 Mbps Ethernet for K=1023 wait time is about 50 msec
Exponential Backoff Goal adapt retransmission
attempts to estimated current load
heavy load random wait will be longer
first collision choose K from 01 delay is K 512 bit transmission times
after second collision choose K from 0123hellip
after ten collisions choose K from 01234hellip1023
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
6
CSMACD (Collision CSMACD (Collision Detection)Detection)
CSMACD can be in one of three states contention transmission or idle
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
7
CSMACD efficiencyCSMACD efficiency
See equation on textbook page 280 Much better than ALOHA also
decentralized simple and cheap
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
8
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless hosts laptop PDA IP phone run applications may be stationary
(non-mobile) or mobile
wireless does not always mean mobility
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
9
Elements of a wireless networkElements of a wireless network
network infrastructure
base station typically connected
to wired network relay - responsible
for sending packets between wired network and wireless host(s) in its ldquoareardquo
eg cell towers 80211 access points
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
10
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless link typically used to
connect mobile(s) to base station
also used as backbone link
multiple access protocol coordinates link access
various data rates transmission distance
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
11
Elements of a wireless networkElements of a wireless network
network infrastructure
infrastructure mode base station
connects mobiles into wired network
handoff mobile changes base station providing connection into wired network
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
12
Elements of a wireless networkElements of a wireless network
Ad hoc mode no base stations nodes can only
transmit to other nodes within link coverage
nodes organize themselves into a network route among themselves
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
6
CSMACD (Collision CSMACD (Collision Detection)Detection)
CSMACD can be in one of three states contention transmission or idle
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
7
CSMACD efficiencyCSMACD efficiency
See equation on textbook page 280 Much better than ALOHA also
decentralized simple and cheap
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
8
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless hosts laptop PDA IP phone run applications may be stationary
(non-mobile) or mobile
wireless does not always mean mobility
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
9
Elements of a wireless networkElements of a wireless network
network infrastructure
base station typically connected
to wired network relay - responsible
for sending packets between wired network and wireless host(s) in its ldquoareardquo
eg cell towers 80211 access points
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
10
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless link typically used to
connect mobile(s) to base station
also used as backbone link
multiple access protocol coordinates link access
various data rates transmission distance
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
11
Elements of a wireless networkElements of a wireless network
network infrastructure
infrastructure mode base station
connects mobiles into wired network
handoff mobile changes base station providing connection into wired network
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
12
Elements of a wireless networkElements of a wireless network
Ad hoc mode no base stations nodes can only
transmit to other nodes within link coverage
nodes organize themselves into a network route among themselves
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
7
CSMACD efficiencyCSMACD efficiency
See equation on textbook page 280 Much better than ALOHA also
decentralized simple and cheap
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
8
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless hosts laptop PDA IP phone run applications may be stationary
(non-mobile) or mobile
wireless does not always mean mobility
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
9
Elements of a wireless networkElements of a wireless network
network infrastructure
base station typically connected
to wired network relay - responsible
for sending packets between wired network and wireless host(s) in its ldquoareardquo
eg cell towers 80211 access points
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
10
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless link typically used to
connect mobile(s) to base station
also used as backbone link
multiple access protocol coordinates link access
various data rates transmission distance
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
11
Elements of a wireless networkElements of a wireless network
network infrastructure
infrastructure mode base station
connects mobiles into wired network
handoff mobile changes base station providing connection into wired network
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
12
Elements of a wireless networkElements of a wireless network
Ad hoc mode no base stations nodes can only
transmit to other nodes within link coverage
nodes organize themselves into a network route among themselves
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
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28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
8
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless hosts laptop PDA IP phone run applications may be stationary
(non-mobile) or mobile
wireless does not always mean mobility
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
9
Elements of a wireless networkElements of a wireless network
network infrastructure
base station typically connected
to wired network relay - responsible
for sending packets between wired network and wireless host(s) in its ldquoareardquo
eg cell towers 80211 access points
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
10
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless link typically used to
connect mobile(s) to base station
also used as backbone link
multiple access protocol coordinates link access
various data rates transmission distance
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
11
Elements of a wireless networkElements of a wireless network
network infrastructure
infrastructure mode base station
connects mobiles into wired network
handoff mobile changes base station providing connection into wired network
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
12
Elements of a wireless networkElements of a wireless network
Ad hoc mode no base stations nodes can only
transmit to other nodes within link coverage
nodes organize themselves into a network route among themselves
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
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40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
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42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
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43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
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45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
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46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
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50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
9
Elements of a wireless networkElements of a wireless network
network infrastructure
base station typically connected
to wired network relay - responsible
for sending packets between wired network and wireless host(s) in its ldquoareardquo
eg cell towers 80211 access points
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
10
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless link typically used to
connect mobile(s) to base station
also used as backbone link
multiple access protocol coordinates link access
various data rates transmission distance
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
11
Elements of a wireless networkElements of a wireless network
network infrastructure
infrastructure mode base station
connects mobiles into wired network
handoff mobile changes base station providing connection into wired network
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
12
Elements of a wireless networkElements of a wireless network
Ad hoc mode no base stations nodes can only
transmit to other nodes within link coverage
nodes organize themselves into a network route among themselves
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
10
Elements of a wireless networkElements of a wireless network
network infrastructure
wireless link typically used to
connect mobile(s) to base station
also used as backbone link
multiple access protocol coordinates link access
various data rates transmission distance
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
11
Elements of a wireless networkElements of a wireless network
network infrastructure
infrastructure mode base station
connects mobiles into wired network
handoff mobile changes base station providing connection into wired network
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
12
Elements of a wireless networkElements of a wireless network
Ad hoc mode no base stations nodes can only
transmit to other nodes within link coverage
nodes organize themselves into a network route among themselves
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
11
Elements of a wireless networkElements of a wireless network
network infrastructure
infrastructure mode base station
connects mobiles into wired network
handoff mobile changes base station providing connection into wired network
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
12
Elements of a wireless networkElements of a wireless network
Ad hoc mode no base stations nodes can only
transmit to other nodes within link coverage
nodes organize themselves into a network route among themselves
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
12
Elements of a wireless networkElements of a wireless network
Ad hoc mode no base stations nodes can only
transmit to other nodes within link coverage
nodes organize themselves into a network route among themselves
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
13
Wireless Link CharacteristicsWireless Link Characteristics
Differences from wired link hellip
decreased signal strength radio signal attenuates as it propagates through matter (path loss)
interference from other sources standardized wireless network frequencies (eg 24 GHz) shared by other devices (eg phone) devices (motors) interfere as well
multipath propagation radio signal reflects off objects ground arriving ad destination at slightly different times
hellip make communication across (even a point to point) wireless link much more ldquodifficultrdquo
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
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42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
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44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
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45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
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46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
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48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
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49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
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50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
14
Wireless network Wireless network characteristicscharacteristics
Multiple wireless senders and receivers create additional problems (beyond multiple access)
AB
C
Hidden terminal problem B A hear each other B C hear each other A C can not hear each
othermeans A C unaware of their
interference at B
A B C
Arsquos signalstrength
space
Crsquos signalstrength
Signal fading B A hear each other B C hear each other A C can not hear each
other interferring at B
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
15
Characteristics of selected Characteristics of selected wireless link standardswireless link standards
384 Kbps384 Kbps
56 Kbps56 Kbps
54 Mbps54 Mbps
5-11 Mbps5-11 Mbps
1 Mbps1 Mbps
80215
80211b
80211ag
IS-95 CDMA GSM
UMTSWCDMA CDMA2000
11 p-to-p link
2G
3G
Indoor
10 ndash 30m
Outdoor
50 ndash 200m
Mid rangeoutdoor
200m ndash 4Km
Long rangeoutdoor
5Km ndash 20Km
80216
80216 10-66GHz 80211a 5GHz ISM band80211bg 24GHz ISM band80215 24GHz ISM band
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
16
IEEE 80211 Wireless LANIEEE 80211 Wireless LAN
80211b 24-2485 GHz
unlicensed radio spectrum
up to 11 Mbps direct sequence
spread spectrum (DSSS) in physical layer
all hosts use same chipping code
widely deployed using base stations
80211a 5-58 GHz range up to 54 Mbps
80211g 24-2485 GHz range up to 54 Mbps
All use CSMACA for multiple access
All have base-station and ad-hoc network versions
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
17
80211 LAN architecture80211 LAN architecture
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka ldquocellrdquo) in infrastructure mode contains
wireless hosts access point (AP)
base station ad hoc mode hosts
only
BSS 1
BSS 2
Internet
hub switchor routerAP
AP
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18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
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35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
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36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
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37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
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39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
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40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
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41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
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42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
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43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
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44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
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45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
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46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
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47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
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48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
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49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
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50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
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51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
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52
Special Interest Group
httpswwwbluetoothorg
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53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
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54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
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55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
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56
ScatternetsScatternets
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57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
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59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
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60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
18
80211 Channels 80211 Channels associationassociation
80211b 24GHz-2485GHz spectrum divided into 11 channels at different frequencies AP admin chooses frequency for AP interference possible channel can be same as
that chosen by neighboring AP host must associate with an AP
scans channels listening for beacon frames containing APrsquos name (SSID) and MAC address
selects AP to associate with may perform authentication [Chapter 8] will typically run DHCP to get IP address in APrsquos
subnet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
19
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
20
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
21
Media Access ControlMedia Access Control
Distributed wireless foundation MAC (DWFMAC) Distributed access control mechanism Optional centralized control on top
Lower sublayer is distributed coordination function (DCF)
Contention algorithm to provide access to all traffic Asynchronous traffic
Point coordination function (PCF) Centralized MAC algorithm Contention free Built on top of DCF
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
22
Distributed Coordination Function Distributed Coordination Function (DCF)(DCF)
DCF sublayer uses CSMACA Uses both physical and virtual carrier sensing
1 MACAW(Multiple Access with Collision Avoidance for Wireless) with virtual carrier sensing
2 1-persistent physical carrier sensing No collision detection
Not practical on wireless network Dynamic range of signals very large Transmitting station cannot distinguish incoming weak
signals from noise and effects of own transmission DCF includes delays
Amounts to priority scheme Interframe space
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
23
CSMACACSMACA
80211 sender1 if sense channel idle for DIFS then
transmit entire frame (no CD)2 if sense channel busy then
start random backoff timetimer counts down while channel idletransmit when timer expiresif no ACK increase random backoff
interval repeat 2
80211 receiver- if frame received OK
return ACK after SIFS (ACK needed due to hidden terminal problem)
sender receiver
DIFS
data
SIFS
ACK
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
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50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
24
Avoiding collisions in Avoiding collisions in CSMACACSMACA
idea allow sender to ldquoreserverdquo channel rather than random access of data frames avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS using CSMA
RTSs may still collide with each other (but theyrsquore short) BS broadcasts clear-to-send CTS in response to RTS RTS heard by all nodes
sender transmits data frame other stations defer transmissions
Avoid data frame collisions completely using small reservation packets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
25
Collision Avoidance RTS-CTS Collision Avoidance RTS-CTS exchangeexchange
APA B
time
RTS(A)RTS(B)
RTS(A)
CTS(A) CTS(A)
DATA (A)
ACK(A) ACK(A)
reservation collision
defer
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
26
virtual channel sensing in virtual channel sensing in CSMACACSMACA
The use of virtual channel sensing in CSMACA
A B
C D
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
27
Point Coordination Function Point Coordination Function (PCF)(PCF)
Alternative access method implemented on top of DCF Polling by centralized polling master (point coordinator) Uses PIFS when issuing polls
PIFS smaller than DIFS Can seize medium and lock out all asynchronous traffic while it
issues polls and receives responses Eg wireless network configured so number of stations with
time-sensitive traffic controlled by point coordinator Remaining traffic contends for access using CSMA
Point coordinator polls to stations asking if any frames to send When poll issued polled station may respond using SIFS Once a station has signed up for polling service at a certain
rate it is effectively guaranteed a certain fraction of the bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
28
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
29
IEEE 80211 MAC LogicIEEE 80211 MAC Logic
Single delay known as interframe space (IFS) Using IFS rules for CSMA
Station with frame senses mediumbull If idle wait to see if remains idle for one IFS If so may
transmit immediatelybull If busy (either initially or becomes busy during IFS)
station defers transmission1 Continue to monitor until current transmission is over2 Once current transmission over delay another IFS
bull If remains idle back off random time and again sensebull If medium still idle station may transmitbull During backoff time if becomes busy backoff
timer is halted and resumes when medium becomes idle
To ensure stability binary exponential backoff used
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
30
IEEE 80211 MAC Timing Basic Access IEEE 80211 MAC Timing Basic Access MethodMethod
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
31
Priority Priority Interframe Space Interframe Space ValuesValues
Use three values for IFS SIFS (short IFS)
Shortest IFS For all immediate response actions
Acknowledgment (ACK) Clear to send (CTS) Poll response
PIFS (point coordination function IFS) Midlength IFS Used by the centralized controller in PCF scheme when issuing polls
Takes precedence over normal contention traffic eg DCF Frames using SIFS have precedence over PCF poll
DIFS (distributed coordination function IFS) Longest IFS Used as minimum delay for asynchronous frames contending for
access
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
32
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
33
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
80211 frame addressing80211 frame addressing
Address 2 MAC addressof wireless host or AP transmitting this frame
Address 1 MAC addressof wireless host or AP to receive this frame
Address 3 MAC addressof router interface to which AP is attached
Address 4 used only in ad hoc mode
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
34
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
80211 frame
R1 MAC addr AP MAC addr
dest address source address
8023 frame
80211 frame addressing80211 frame addressing
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
35
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
80211 frame more80211 frame more
duration of reserved transmission time (RTSCTS)
frame seq (for reliable ARQ)
frame type(RTS CTS ACK data)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
36
hub or switch
AP 2
AP 1
H1 BBS 2
BBS 1
80211 mobility within same 80211 mobility within same subnetsubnet
router H1 remains in same
IP subnet IP address can remain same
switch which AP is associated with H1
self-learning switch will see frame from H1 and ldquorememberrdquo which switch port can be used to reach H1
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
37
80211 Wireless LANs80211 Wireless LANs
MAC protocols DCF CSMACA
80211 Frame format and addressing Physical layer issues
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
38
IEEE 80211 Protocol IEEE 80211 Protocol ArchitectureArchitecture
Point Coordination Function (PCF)
OFDM
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
39
Wireless Physical Layer Wireless Physical Layer Physical layer conforms to OSI (five options)
1997 80211 infrared FHSS DHSS 1999 80211a OFDM and 80211b HR-DSSS 2001 80211g OFDM
80211 Infrared Two capacities 1 Mbps or 2 Mbps Range is 10 to 20 meters and cannot penetrate walls Does not work outdoors
80211 FHSS (Frequence Hopping Spread Spectrum) Offers good resistance to multipath fading 79 non-overlapping channels each 1 Mhz wide at low end of 24
GHz ISM band Same pseudo-random number generator used by all stations Dwell time min time on channel before hopping (400msec)
Multipath Fading
The deflection of a radio signal off obstacles which can cause interference during signal reception Multipath occurs when a radio signal is received directly by an antenna and later the same signal is received again reflected from a building or mountain Ghosting of a TV signal is a form of muiltipath Under certain conditions two or more of the signals can interfere with each other and create fading (a loss of signal) in the communications link
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
40
Wireless Physical Layer Wireless Physical Layer 80211 DSSS (Direct Sequence Spread Spectrum)
Spreads signal over entire spectrum using pseudo-random sequence (similar to CDMA see Tanenbaum sec 262)
Each bit transmitted using an 11 chips Barker sequence PSK at 1Mbaud
1 or 2 Mbps 80211a OFDM (Orthogonal Frequency Divisional
Multiplexing) Compatible with European HiperLan2 Good immunity to multipath fading 54Mbps in wider 55 GHz band transmission range is limited Uses 52 FDM channels (48 for data 4 for synchronization) Encoding is complex ( PSM up to 18 Mbps and QAM above this
capacity) Eg at 54Mbps 216 data bits encoded into into 288-bit symbols More difficulty penetrating walls
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
41
Wireless Physical Layer Wireless Physical Layer
80211b HR-DSSS (High Rate Direct Sequence Spread Spectrum)
11a and 11b shows a split in the standards committee 11b approved and hit the market before 11a Up to 11 Mbps in 24 GHz band using 11 million chipssec Note in this bandwidth all these protocols have to deal with
interference from microwave ovens cordless phones and garage door openers
Range is 7 times greater than 11a 11b and 11a are incompatible
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
42
Wireless Physical Layer Wireless Physical Layer 80211g OFDM(Orthogonal Frequency Division
Multiplexing) An attempt to combine the best of both 80211a and
80211b Supports bandwidths up to 54 Mbps Uses 24 GHz frequency for greater range Is backward compatible with 80211b
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
43
Data Link Layer Data Link Layer Road Road MapMap
Data link layer design issues Framing Error Control Reliable data transfer and flow control
Example data link protocols HDLC and PPP
Multiple Access Protocols Static channel allocation Dynamic channel allocation
LAN technologies and their MAC protocols Ethernet WiFi and WiMax and WPAN
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
44
Broadband WirelessBroadband Wireless
Wireless MAN or Wi-Max IEEE 80216 standard for bridging the ldquolast milerdquo between
ISPs and their customers as replacement for costly-todeploy fiber opticDSLcable modem links (Broadband Wireless Access BWA)
Original PHY-Layer 10-66 GHz line-of-sight connections with fixed directed
outdoor antennas single-carrier TDD or FDD with TDMA in the uplink
In 80216a a second PHY-layer was added to make the standard suitable for residential applications (no line-of-sight more multi-path propagation)
2-11 GHz both licensed and license-exempt non-line-of-sight operation possible support for advanced antenna systems three air interfaces single carrier OFDM with TDMA or OFDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
45
Comparison of 80211 and Comparison of 80211 and 80216a80216a
IEEE 80211 IEEE 80216a
Spectrum License-exempt (ISM)
License-exempt or licensed
Max Speed 54 Mbps (11a amp g) 70 Mbps
Range 100 m 40 km
QoS None Yes
Coverage Indoor Opt Outdoor Opt
Users Hundreds Thousands
Security WPAWEP Triple-DES (128-bit) and RSA (1024-bit)
Service Levels None Yes
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
46
The 80216 Protocol StackThe 80216 Protocol Stack
The 80216 Protocol Stack
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
47
The 80216 Physical LayerThe 80216 Physical Layer
The 80216 transmission environmentUse error-correction code Hamming code
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
48
The 80216 Physical Layer (2)The 80216 Physical Layer (2)
FDD + TDD
Example Frames and time slots for time division duplexing(TDD)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
49
The 80216 MAC Sublayer The 80216 MAC Sublayer ProtocolProtocol
bull Downstream channelbull Base station decide
bull Upstream channelbull Competing uncoordinated subscribersbull Related to QoS issuesbull Four Connection-Oriented Service Classes
bull Constant bit rate service (uncompressed voice)bull Real-time variable bit rate service (compressed
multimedia)bull Non-real-time variable bit rate service (not real time
heavy transmissions large file transfers)bull Best efforts service (everything else)
bull Decided when connection is set up
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
50
Mradius ofcoverage
S
SS
P
P
P
P
M
S
Master device
Slave device
Parked device (inactive)P
80215 personal area network80215 personal area network
less than 10 m diameter replacement for cables
(mouse keyboard headphones)
ad hoc no infrastructure masterslaves
slaves request permission to send (to master)
master grants requests 80215 evolved from
Bluetooth specification 24-25 GHz radio band up to 721 kbps
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
51
Bluetooth HistoryBluetooth History 1994 ndash Ericsson study completevision 1995 ndash Engineering work begins 1997 ndash Intel agrees to collaborate 1998 ndash Bluetooth SIG formed
Ericsson Intel IBM Nokia and Toshiba 1999 ndash Bluetooth Specification 10A
SIG promoter group expanded 3Com Lucent Microsoft amp Motorola
2000 ndash Bluetooth Specification 10B 2000+ adopters 2001 ndash First retail products released Specification 11 2003 ndash Bluetooth Specification 12 2004 ndash Bluetooth Specification 20
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
52
Special Interest Group
httpswwwbluetoothorg
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
53
Bluetooth ArchitectureBluetooth Architecture
Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel (hop frequency)
and phase Scatternet
Inter-piconet communication Device in one piconet may exist as master or
slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
54
PiconetPiconet Before a connection is created
a device is in ldquostandbyrdquo mode periodically listen for messages every 128 sec
Devices are connected in an ad hoc fashion called piconet
8 active devices in a piconet each piconet has 1 master and up to 7 slaves
Other devices within the piconet will be considered ldquoparkedrdquo (255 parked)
Parked devices as well as the slaves are synchronized to the master
M = MasterS = Slave
P = ParkedSB = Standby
M
S
P
SB
S
S
P
P
SB
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
55
ScatternetScatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another No device can be master of two piconets
M=MasterS=SlaveP=ParkedSB=Standby
M
S
P
SB
S
S
P
P
SB
M
S
S
P
SB
Piconets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
56
ScatternetsScatternets
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
57
Bluetooth ApplicationsBluetooth Applications
Originally conceived as a cable replacement technology Eliminates need for numerous cable attachments for connection
Other usage models began to develop Personal Area Network (PAN) Datavoice access points Ad-hoc networks
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
58
Core Bluetooth ProductsCore Bluetooth Products
Notebook PCs amp desktop computers
Printers PDAs Other handheld devices Cell phones Wireless periperals
Headsets Cameras
Access Points
CD Player TVVCRDVD Telephone Answering
Devices Cordless Phones Cars
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
59
Costs of Bluetooth ChipsCosts of Bluetooth Chips
$1500
$750
$450$315 $252 $202
$000
$200
$400
$600
$800
$1000
$1200
$1400
$1600
2000 2001 2002 2003 2004 2005
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
60
Bluetooth Standards Bluetooth Standards DocumentsDocuments
Core specifications Details of various layers of Bluetooth protocol
architecture Profile specifications
Use of Bluetooth technology to support various applications
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
61
Bluetooth Protocol StackBluetooth Protocol Stack
The 80215 version of the Bluetooth protocol architecture
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
62
Protocol ArchitectureProtocol Architecture
Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control
protocols Adopted protocols
Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol
(L2CAP) Service discovery protocol (SDP)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
63
Bluetooth Radio LayerBluetooth Radio Layer
24 GHz ISM (Industrial Scientific Medical) Open Band
Globally free available frequency 79 MHz of spectrum = 79 channels Frequency Hopping (FHSS Frequency Hopping Spread
Spectrum) amp Time Division Duplex (1600 hopssecond) Disadvantage interfere with IEEE 80211b products
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
64
Unlicensed Radio SpectrumUnlicensed Radio Spectrum
902 Mhz
928 Mhz
26 Mhz 835 Mhz 125 Mhz
24 Ghz
24835 Ghz5725 Ghz
5785 Ghz
cordless phonesbaby monitorsWireless LANs
80211BluetoothMicrowave oven
80211aHyperLan
33cm 12cm 5cm
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
65
Frequency HoppingFrequency Hopping
Total bandwidth divided into 1MHz physical channels
FH occurs by jumping from one channel to another in pseudorandom sequence
Hopping sequence shared with all devices on piconet
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
66
Frequency HoppingFrequency Hopping
frequency hopping spread spectrum 2402 GHz + k MHz k=0 hellip 78 1600 hops per second
1Mhz
1 2 3 79
835 Mhz
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
67
Radio SpecificationRadio Specification Low Power Consumption
Three power classes defined with max output power from 1 mW (Class 3) to 100 mW (Class 1)
Class 1 Outputs 100 mW for maximum range Power control mandatory Provides greatest distance
Class 2 Outputs 24 mW at maximum Power control optional
Class 3 Nominal output is 1 mW Lowest power
Short Range 10-100 Meter Class 1 ndash 100 meter (300 feet) Class 2 ndash 20 meter (60 feet) Class 3 ndash 10 meter (30 feet)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
68
Baseband LayerBaseband Layer
MAC sublayer + some elements of physical layer
Deal with how the master controls time slots and how these slots are grouped into frames
Piconet access Bluetooth devices use time division duplex
(TDD) Access technique is TDMA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
69
QuizQuiz
Describe Non-persistent CSMA and p-Persistent CSMA (including 1-persistent)
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
70
QuizQuiz
Describe CSMACD
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA
Wireless Ad Hoc amp Sensor Networks Wireless Ad Hoc amp Sensor Networks MAC Protocol
71
QuizQuiz
Describe CSMACA