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BROADBAND WIRELESS
802.16
PRESENTED BY :
ANKITA PANDEY
ME REGULAR (ECE)
INTRODUCTION WHAT IS WIMAX FEATURES OF WIMAX WIMAX SYSTEM MODES OF OPERATION
• LOS• NLOS
802.16 STANDARDS THE 802.16 PROTOCOL STACK
• PHYSICAL LAYER• MAC LAYER
COMPARISON OF WIMAX WITH OTHER WIRELESS TECHNOLOGIES• WIMAX Vs 3G• WIMAX Vs WiFi
WIMAX - SECURITY FUNCTIONS WIMAX ADVANTAGES AND DRAWBACKS APPLICATIONS FUTURE OF WIMAX SUMMARY REFERENCES
What is Broadband Wireless?
Broadband wireless is high-speed Internet service via wireless technology, available in Internet cafés, local “hot spots” within many cities, private businesses and many homes.
The advantage of broadband wireless is that the computer receiving the Internet signal need not be tethered by an Ethernet or network cable to the broadband modem or router.
A broadband wireless modem receives the service and transmits it via radio waves to the immediate surrounding area.
The most common way to take its advantage by using a laptop, with a wireless broadband adapter, commonly available in a portable computer (PC) card format.
Broadband Wireless
LIMITING FACTOR : In today’s world, a large number of wireless transmission
technologies exist. These technologies are distributed over different network families
depending upon the network scale such as PAN, WLAN, WMAN and WAN.
The rapid growth of internet and increasing interest in portable computing devices are likely to push demand for high-speed wireless data services with aggregated higher information bit rates.
There are basically three limiting factors for transmitting high data rate over the wireless medium that mainly include multipath fading, delay spread and co-channel interference .
Technologies that promise to deliver higher data rates are attracting more and more vendors and operators towards them.
Broadband Wireless
SOLUTION : To address this issue a very interesting solution has been defined by
the IEEE 802.16 working group . WIMAX provides a 21st century platform for broadband wireless
access. WIMAX stands for worldwide interoperability for microwave
access .
WIMAX / IEEE 802.16 Wimax networks refer to broadband wireless networks that are
based on the IEEE 802.16 standard, which ensures compatibility and interoperability between broadband wireless access equipment .
The IEEE 802.16 standards define how wireless traffics move between subscriber equipment and core networks.
WiMAX was designed for the transmission of multimedia services (voice, Internet, email, games and others) at high data rates.
Source: SHASHI JAKKU
Features Use microwave for the wireless transfer of data. Specifies a frequency band in the range between 2 GHz to 66 GHz. For high speed wireless networking. Basically, Wimax is a wireless internet service that is capable of
covering a wide geographical area by serving hundreds of users at a very low cost.
Uses OFDM ,good for multipath environments. It includes TDD and FDD duplexing support. Flexible channel sizes (3.5 MHz,5 MHz,10MHz) An easy and fast system to install. Leading to low installation cost, when compared to fiber ,cable or
DSL deployments.
Data Rate vs Mobility
802.16 STANDARDS
802.16.1 : (10-66 GHz, line-of-sight, up to 134Mbit/s).
802.16.2 : (minimizing interference between coexisting WMANs).
802.16a : (2-11 Ghz, Mesh, non-line-of- sight).
802.16b : (5-6 Ghz). 802.16c : (detailed system profiles). P802.16e : (Mobile Wireless MAN).
A WIMAX TOWER Similar in concept to a cell-phone tower - A single WiMAX
tower can provide coverage to a very large area as big as ~8,000 square km.
A WIMAX CLIENT TERMINAL The terminal receiver and antenna could be a small box or
Personal Computer Memory card, or they could be built into a laptop.
WIMAX System
WIMAX System
WiMAX
WiMAX uses radio microwave technology to provide wireless internet service to computers and other devices that are equipped with WiMAX compatible chips for example PDA’s, cell phones etc.
It works more or less like cellular network technology. The theoretical range of WiMAX is up to 30 miles and achieves
data rates up to 75 Mbps WiMAX operates in similar manner as Wi-Fi but with two very
convincing differences as compared to Wi-Fi, these are :o Data rate o Data range
MODES OF OPERATIONWiMax can provide 2 forms of wireless service:
LOS. NLOS.
NLOS
These create multiple signals that will arrive at a receiver at different times, from different paths, and with different strength.
Wireless systems developed for NLOS environment have to incorporate a number of techniques to overcome this problem and that make the systems more complex than those for LOS.
Wi-Fi sort of service, where a small antenna on a computer connects to the tower.
Uses lower frequency range (2 to 11 GHz). Non-line-of-sight (NLOS) is a condition where a signal from a wireless
transmitter passes several obstructions before arriving at a wireless receiver. The signal may be reflected, refracted, diffracted, absorbed or scattered.
LOS Where a fixed antenna points straight at the WiMax tower from a rooftop
or pole. The LOS connection is stronger and more stable. Higher throughput. Uses higher frequencies: reaching a possible 66 GHz. Through stronger LOS antennas, higher range can be achieved: up to 50km
radius. Line-of-sight (LOS) is a condition where a signal travels over the air
directly from a wireless transmitter to a wireless receiver without passing an obstruction.
LOS is an ideal condition for a wireless transmission because the propagation challenge only comes from weather or atmospheric parameters and the characteristic of its operating frequency.
802.16 Standards History
802.16a(Jan 2003)
IEEE 802.16a (January 2003)• Extension for 2-11 GHz• Targeted for non-line-of-sight,• Point-to-Multi-Point applications “LAST MILE”
broadband access.
802.16(Dec 2001)
IEEE 802.16 (2001)• Original fixed wireless broadband air Interface for 10 – 66 GHz.• Connection-oriented, TDM/TDMA MAC•Targeted for Line-of-sight only•Point-to-Multi-Point applications802.16c
(2002)
IEEE 802.16c (2002)Represents a 10 to 66 GHz system profile that standardizes more details of the technology.
802.16d (802.16-2004)
(Oct 2004)
IEEE 802.16d (Oct 2004)• Combines both IEEE 802.16 and 802.16a• Some modifications to the MAC and PHY
802.16e(802.16-2005)
(Dec 2005)
IEEE 802.16e (2005)• MAC/PHY Enhancements to support subscribers
moving at vehicular speeds.
802.16 StandardsIEEE 802.16 IEEE
802.16a/802.16d IEEE 802.16e
Completed Dec 2001 Oct 2004 Dec 2005
Spectrum 10 - 66 GHz 2 – 11 GHz 2 - 6GHz
Application Backhaul Wireless DSL and Backhaul
Mobile Internet
Channel Conditions Line of Sight Only Non-Line of Sight Non-Line of Sight
Bit Rate 32 – 134 Mbps Up to 75 Mbps Up to 15 Mbps
Modulation QPSK,16QAM and 64QAM
OFDM ,QPSK,16QAM,
64QAM OFDMA
Channel Bandwidths 20,25 and 28 MHz 1.5 and 20 MHZ Same as 802.16d
WiMAX : Technology
Wide Coverage
Wide Coverage
MobilityMobility
SLASLA
PortablePortable
Flexible
Architecture
Flexible
Architecture
Low CostLow Cost
HighCapacity
HighCapacity
HighSecurity
HighSecurity
QuickDeployment
QuickDeployment
QoSQoS
WiMAXWiMAX
The WiMAX standard has been developed with many objectives in mind
Comparison between Fixed and Mobile WiMAX
Why wimax is necessary?
DSL and cable modems No mobility. Huge infrastructure investment
Cellular systems Fundamentally designed for voice Poor spectral efficiency
Wi-Fi/802.11 No mobility support Short range Not a broadband technique on its own
WHY WIMAX NECESSARY ? CONT..
Wimax /802.16 Variable and potentially large bandwidth. Efficient exploitation of diversity.
Time (Scheduling ,adaptive modulation) Frequency (Scheduling ,adaptive modulation) Space (Space codes , MIMO)
Packet switched architecture.
WIMAX CHIPS
DEPLOYMENT SCENARIOS IEEE 802.16/WiMAX technology intends to provide broadband
connectivity to both fixed and mobile users in a wireless metropolitan area network (WMAN) environment. To provide flexibility for different applications, the standard supports two major deployment scenarios.
Last-mile BWA: In this scenario, broadband wireless connectivity is provided to
home and business users in a WMAN environment. The operation is based on a point-to-multipoint single hop
transmission between a single base station (BS) and multiple subscriber stations (SSs).
DEPLOYMENT SCENARIOS
Backhaul networks :
This is a multihop (or mesh) scenario where a WiMAX network works as a backhaul for cellular networks to transport data/voice traffic from the cellular edge to the core network (Internet).
Backhaul is a technology that is linked with carrying traffic among circulated sites.
Wimax backhaul is getting data from one point and spreading it over a network with high data rates and low price.
Uses OFDMA (Orthogonal Frequency Division Multiple Access). It is specially designed for Wide Area Network with higher
throughput. Another very unique feature of Wimax backhaul is that it gives
protection against theft of services.
DEPLOYMENT SCENARIOSCoverage range up to 50km and speeds up to 70Mbps(shared among users).
The 802.16 Protocol Stack
The 802.16 Protocol Stack
The 802.16 Physical Layer(1/3)
Physical and transmission layer functions:
• Encoding/decoding of signals
• Preamble generation/removal
• Bit transmission/reception
• The PHY converts MAC layer frames into signals to be transmitted across the air interface.
• Traditional narrow band radio is used with conventional modulation schemes. QPSK: (longer distance) QAM-16: (medium distance) QAM-64: (short distance)
The 802.16 Physical Layer(2/3)
The 802.16 Physical Layer(3/3)
802.16 provides a more flexible way to allocate the bandwidth.
Two schemes are usedo FDDo TDD
The 802.16 MAC Layer
The primary task of the WiMAX MAC layer is to provide an interface between the higher transport layers and the physical layer.
The MAC layer takes packets from the upper layer,these packets are called MAC service data units (MSDUs) and organizes them into MAC protocol data units (MPDUs) for transmission over the air.
The 802.16 MAC is designed for point-to-multipoint (PMP) applications and is based on collision sense multiple access with collision avoidance (CSMA/CA).
Mac features
The MAC incorporates several features suitable for a broad range of applications at different mobility rates, such as the following:
Privacy key management (PKM) for MAC layer security. Broadcast and multicast support. High-speed handover and mobility management primitives. Three power management levels, normal operation, sleep and idle. Header suppression, packing and fragmentation for efficient use of
spectrum. Support for integrated voice/data connections.
The WiMAX MAC
The WiMAX MAC comprises three sublayers
ATM, Ethernet,
Internet Protocol
ATM, Ethernet,
Internet Protocol
Packing,Fragmentation,
ARQ, QoS
Packing,Fragmentation,
ARQ, QoS
Autentication,Key Exchange,
Privacy (encrypt.)
Autentication,Key Exchange,
Privacy (encrypt.)
Convergence sublayer
MAC Common part sublayer
Security sublayer
Convergence sublayer The service specific convergence sublayer (CS) provides any
transformation or mapping of external network data, received through the CS service access point (SAP) into MAC SDUs received by the MAC CPS through the MAC SAP.
Accepting higher layer protocol data units (PDUs) from the higher layer
Performing classification of higher layer PDUs. Associating them to the proper service flow identified by the
connection identifier (CID). Delivering CS PDUs to the appropriate MAC SAP.
MAC Common part sublayer Defines multiple-access mechanism Bandwidth allocation Connection establishment Connection maintenance Connection-oriented protocol Assign connection ID to each service flow.
Security sublayer Deals with privacy and security. The security sublayer provides subscribers with privacy or
confidentiality across the broadband wireless network. It manages :
Authentication Secure key exchange Encryption
IEEE 802.16 MAC Data Packet Encapsulations
PHSI
MAC PDU
Ethernet Packet
Ethernet Packet
Packet PDU(e.g., Ethernet)
CS PDU(i.e., MAC SDU)
HT
FEC block 1
CRCMAC PDU Payload
OFDMsymbol
1
PHY Burst(e.g., TDMA burst)
PreambleOFDMsymbol
2
OFDMsymbol
n
......
FECFEC Block 2 FEC block m
......FEC Block 3
8-bit payload header suppression index field
The 802.16 MAC Frame Format
Each MAC packet consists of the three components,
1) A MAC header
which contains frame control information.
2) A variable length frame body
which contains information specific to the frame type.
3) A frame check sequence (FCS)
which contains an IEEE 32-bit cyclic redundancy code (CRC)
The 802.16 Frame Structure
A GENERIC FRAME
39
The 802.16 Frame Structure HT(Header type): For generic frame,HT=0 EC (Encryption control)
o 0 = Payload is not encrypted or payload is not included.o 1 = Payload is encrypted.
Type : This field identifies the frame type ,whether packing and fragmentation is present.
CI (CRC indicator)o 1 = CRC is included .o 0 = No CRC is included.
EKS (Encryption key sequence) : Which encryption key is used. Length: Complete length of the frame including header. Connection ID: Which connection this frame belongs to. Header CRC: Header check sequence. An 8-bit field used to detect errors
in the header.Header check-sum using 100000111. ESF(Extended subheader) ESF=0 ,absent:ESF=1.present
The 802.16 Frame Structure
BANDWIDTH REQUEST (BR) HEADER
The 802.16 Frame Structure The second header type ,for frames that request bandwidth. HT(Header type): HT=1 EC (Encryption control)= 0,Payload is not encrypted or payload is
not included. BR field indicate the number of bytes requested,or telling how much
bandwidth is needed to specified number of bytes. Bandwidth request frames do not carry a payload or full frame CRC.
Fragmentation and packing
Packing The MAC layer may pack multiple MAC SDUs into one single
MAC PDU. When the radio channel is relatively good, this allows a better use of available resources.
Fragmentation MSDU might be fragmented by the transmitter to form several
MPDUs. The advantage of fragmentation is to lower the risk of losing a whole MSDU to the risk of losing part of it, a fragment. This is interesting when the radio channel is relatively bad or packets too long.
IEEE 802.16 MAC – MAC SDU Fragmentation
FEC block1
OFDMsymbol
1
PHY Burst
Pre.
MAC SDU
OFDMsymbol
n1
......
FEC FEC Blockm1
......
MAC SDUseg-1
HT CRCMAC PDU PayloadHT CRC
MAC PDUPayload
A MAC SDU can be fragmented into multiple segments, eachsegment is encapsulated into one MAC PDU
FEC block1
OFDMsymbol
1
PHY Burst
Pre.OFDMsymbol
n2
......
FEC Blockm2
......
HT CRCMAC PDUPayload
MAC SDUseg-2
MAC SDUseg-3
FSH
FSH
FragmentationSub-Header
(8 bits)
FSH
IEEE 802.16 MAC – MAC SDU Packing
MACSDU 1
Fixed size MSDUs, e.g., ATMCells, on the same connection
HT CRCMAC PDU Payload
HT CRC
Packing with fixed size MAC SDUs (no packing sub-header is needed)
......
PSH
MACSDU 2
MACSDU k
Packing with variable size MAC SDUs (Packing Sub-Heade is neeeded)
PSH ...... PSH
MAC SDU orseg. 1 MAC SDU or seg 2
MAC SDU orseg n
Variable sizeMSDUs or MSDUsegments, e.g.,IP packets, on
the sameconnection
PackingSub-Heder
(16 bits)
Spectrum Influence in WiMAX Network
The best advantage of WiMAX system is that, it can operate in both license and license free frequency bands which helps for global deployment of WiMAX and have certain advantages over the wired network.
Channel bandwidth which increases the capacity of the WiMAX network by reusing the frequency.
WiMAX License Spectrum Most of the country around the world uses 2.5 GHz band as a
license frequency band for WiMAX application. Since allocation of spectrum varies among country to country, so
spectrum allocation can varies between 2.6 to 4.2 GHz. It can effectively deliver point-to-multipoint spectrum to large
number of users. It has strong bandwidth capacity. It is also good for interference free services and better QoS.
WiMAX Unlicensed Spectrum The globally available unlicensed spectrum is 2.4 GHz Industrial,
Scientific and Medical band (ISM). Unlicensed spectrum is better for lower cost network deployment
in rural areas, developing countries, emerging markets and developed countries with underdeveloped areas.
It is also good for quickly deployed the services rather that wasting time for the license permit.
It can be used in a point to point (PTP) communication in a small population area or a point-to-multipoint (PMP) communication in a rural areas or a place like college campus, where interference can be controlled .
Comparison of WiMAX with Other Wireless Technologies
When WiMAX was taken into consideration for replacing the DSL and cable modems and providing an enhanced solution to the exiting solution (802.11 standards), no one thought that WiMAX could be so strong and powerful that it could replace or even proves to be a good competitor for 3G and beyond cellular networks.
A Comparison of WiMAX & 3G Introduces OFDMA, which improves spectrum efficiency around
two times more than current 3G technologies. Enables a wide range of advanced antenna systems including MIMO,
space-time coding and spatial multiplexing. It thus increases the covering range of WiMAX .
WiMAX spectrum is more economical than 3G. Higher Throughput. Low Cost. Lower Latency.
A Comparison of WiMAX & Wifi
The fastest Wi-Fi connection can transmit up to 54 megabits per second under optimal conditions. WiMAX should be able to handle up to 70 megabits per second.
WiMAX outdistances Wi-Fi by miles. Wi-Fi's range is about 100 feet (30 m). WiMAX will blanket a radius of 30 miles (50 km) with wireless access. The increased range is due to the frequencies used and the power of the transmitter .
The original WiMAX standard (IEEE 802.16) proposes the usage of 10-66 GHz frequency spectrum for the WiMAX transmission, which is well above the Wi-Fi range (up to 5 GHz maximum).
A Comparison of WiMAX & Wifi
WiMAX specifications also provides much better facilities than Wi-Fi, providing higher bandwidth and high data security by the use of enhanced encryption schemes.
WiMAX can also provide service in both Line of Sight (LOS) and Non-Line of Sight (NLOS) locations, but the range will vary accordingly.
COMPARISION TABLE
WiMAX - Security Functions Security is handled by a privacy sublayer within the WiMAX MAC. The key
aspects of WiMAX security are as follow:
Support for privacy: User data is encrypted using cryptographic schemes. WiMAX uses the Advanced Encryption Standard (AES) to produce
cipher text. The cipher text is then transmitted over the wireless network and cannot
be understood by an eavesdropper.
Device/user authentication: WiMAX provides a flexible means for authenticating users to prevent
unauthorized use.
Support for fast handover: A three-way handshake scheme is supported to optimize the
reauthentication mechanisms for supporting fast handovers.
advantages of WiMAX
Long Range: Perhaps the most significant advantage of WiMAX over other wireless technologies is the range it provides. WiMAX has a communication range of up to 30 miles. This is enough to cover a medium size city.
Higher Bandwidth: Before WiMAX, the existing wireless technologies have various issues that are mostly related to the bandwidth. WiMAX provides high data rates which makes.
Low cost: Although the cost to install a WiMAX base station would be around 20,000 $ but still it would be much less cheaper when it comes to the deployment of wireless network.
Security : Security options of Wimax Technology also offer very high security because of encryption system used by Wimax.
advantages of WiMAX
Multi - functionality within Wimax Technology : Wimax Technology perform a variety of task at a time such as offering high speed internet, providing telephone service, transformation of data, video streaming, voice application etc.
Wimax Coverage : The single station of Wimax can operate and provide coverage for hundred of users at a time and manage sending and receiving of data at very high speed with full of network security.
Wimax Infrastructure : Wimax infrastructure is very easy and flexible therefore it provides maximum reliability of network.
Disadvantages
WiMAX is basically a power sensitive technology, meaning that it heavily relies on strong electrical support.
A Line of sight is required in order to make a wireless data communication connection extending over 6 miles or more. Means it is needed for more distant connections.
Bandwidth is shared among users in a given radio sector. If there are many users in one sector, they will have lower speed.
Bad weather conditions such as rain could interrupt the signal. Other wireless equipment could cause interference. WiMAX is a very power-consuming.
APPLICATIONBroadband Internet access real time applications Video streaming VoIP, Video on Demand Video Conference Surveillance and monitoring (forests, volcano, etc.)
Other possible real time complex applications E-learning General applications and services based on IP connectivity.
Applications
FIGURE SHOWS THE APPLICATIONS OF WIMAX TO PROVIDE INTERNET ACCESS OVER BIG GEOGRAPHICAL AREA.
APPLICATIONs Security: This is crucial for telemedicine services. Patient information must
be communicated in a secure and reliable manner. The MAC layer security feature in the IEEE 802.16/WiMAX standard can provide access control and encryption functionalities for wireless telemedicine services.
WiMAX-based wireless telemedicine network.
APPLICATIONs
APPLICATIONS
FUTURE OF WIMAXAlong with the forthcoming standardization, WiMAX has the
potential to substitute 3G and become a promising 4G.WiMax is a technology which considered as the first step toward 4G.
Today WiMax is operating as second generation and third generation technology but in near future it would be substantial 4G technology.
It is expected that WiMax becomes the dominant standard for Wireless MAN in the world market, at least, in fixed broadband networks.
WiMAX networks can provide very-high-speed wireless connectivity in presence of mobility.
802.16– WiMAXLeading BWA Standards –IEEE 802.16m
BTZigBee
Wireless Broadband
SUMMARY
BROADBAND WIRELESS Broadband wireless is high-speed Internet service via wireless technology.
WIMAX / IEEE 802.16 Wimax networks refer to broadband wireless networks that are based on the
IEEE 802.16 standard, which ensures compatibility and interoperability between broadband wireless access equipment .
WIMAX FEATURE High data rates Wide frequency band operation Advanced Error Correction techniques Adaptive modulation and coding
802.16 STANDARDS HISTORY
SUMMARY
DEPLOYMENT SCENARIOS Last-mile BWA Backhaul networks
WIMAX SYSTEMMODES OF OPERATIONTHE 802.16 PROTOCOL STACK
The 802.16 Physical Layer The 802.16 MAC Layer The 802.16 Frame format
COMPARISON BETWEEN FIXED AND MOBILE WIMAX
SUmmary
COMPARISON OF WIMAX WITH OTHER WIRELESS TECHNOLOGIES.
WIMAX - SECURITY FUNCTIONS.WIMAX ADVANTAGES AND
DRAWBACKS.APPLICATION.FUTURE OF WIMAX.
REFERENCES
• Andrew S. Tanenbaum “Computer Networks” fourth edition ;prentice hall of India 2005.
• IEEE 802.16-2004 (802.16REVd)• IEEE 802.16-2005 (802.16e)• “IEEE Standard 802.16: A Technical Overview of the Wireless MAN Air
Interface for Broadband Wireless Access,” C. Eklund et al., IEEE Communication Magazine, June 2002
• WiMAX Forum: www.wimaxforum.com (28 March 2011)
• http://en.wikipedia.org/wiki/WiMax (28 March 2011)
• www.goingwimax.com (www.goingwimax.com(27April 2011)
• http://www.broadband.gov/fieldevents/fh_public_safety/pavlak.ppt
• ( 2 April 2011)
• http://www.broadband.gov/docs/ws_tech_fixed_bb/ws_technology_fixed_broadb (7April 2011)
REFERENCES• http://www.itr-rescue.org/bin/pubdocs/mtg-weekly/9-16-05%2520Karim
%2520Hassib%2520-%2520WiMAX.pp (7April 2011)
• http://www.ieee-centennial.org/Speaker_Notes/20050216_Wireless_Broadband_IEEE.pp (23April 2011)
• http://www.novarum.com/documents/Novarum1H2007Overview.pdf
(23April 2011)
• IEEE Std 802.16e-2005, “IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems,” IEEE Std 802.16e-2005, February 2006.
• Changazi, S.() UWiMAX 802.16e and Its Comparison with Other 3G TechnologiesU , Advanced Telecommunication ETS190.
Thank you.
