View
222
Download
4
Category
Preview:
Citation preview
7/28/2019 802.11 standards1
1/10
1AITA\SWBU\CWNA\08
802.11 Standards
7/28/2019 802.11 standards1
2/10
2AITA\SWBU\CWNA\08
Unlicensed Frequency Bands
ExtremelyLow
VeryLow
Low Medium High VeryHigh
Infrared VisibleLight
Ultra-violet
X-Rays
Audio
AM Broadcast
Short Wave Radio FM Broadcast
TelevisionInfrared wireless LAN
Cellular (840 MHz)
NPCS (1.9 GHz)
902-928 MHz26 MHz
5 GHz(IEEE 802.11)
HiperLAN
HiperLAN 2802.11a
2.4 2.4835 GHz
83.5 MHz(IEEE 802.11)
802.11b and 802.11g
UltraHigh
SuperHigh
7/28/2019 802.11 standards1
3/10
3AITA\SWBU\CWNA\08
Three Wireless Technologies
The Laws of Radio Dynamics:
Higher Data Rates = Shorter Transmission RangeHigher Power Output = Increased Range, but Lower Battery LifeHigher Frequency Radios = Higher Data Rates Shorter Ranges
802.11b 802.11a 802.11g
2.4 GHz 5 GHz 2.4 GHz
Worldwide US/AP Worldwide
11 Mbps 54 Mbps 54 Mbps
FrequencyBand
Availability
MaximumData rate
OtherServices(Interference)
Cordless PhonesMicrowave OvensWireless VideoBluetooth Devices
Cordless PhonesMicrowave OvensWireless VideoBluetooth Devices
HyperLANDevices
7/28/2019 802.11 standards1
4/10
4AITA\SWBU\CWNA\08
IEEE 802.11 Standard
IEEE 802.11 became a standard in July 1997
2.4 GHz at 2 Mbps Frequency Hopping Spread Spectrum (FHSS)and Direct Sequence Spread Spectrum (DSSS)
IEEE 802.11a and 802.11b became standards in September 1999
802.11a 5 GHz at 54 Mbps OFDM
802.11b 2.4 GHz at 11 Mbps DSSS
IEEE 802.11g is scheduled to be ratified in 2003
802.11g 2.4 GHz at 54 Mbps OFDM
802.11 promises true vendor interoperability
7/28/2019 802.11 standards1
5/10
5AITA\SWBU\CWNA\08
802.11b Radio Modulation
Cisco Aironet Access Points Three different types of modulation
Depending upon the data rate:
Binary Phase Shift Keyed (BPSK) Quadrature Phase Shift Keying
(QPSK)
Complementary Code Keying
(CCK) BPSK Modulation Example
7/28/2019 802.11 standards1
6/10
6AITA\SWBU\CWNA\08
802.11b Access Point Coverage
1 Mbps DSSS
5.5 Mbps DSSS
11 Mbps DSSS
2 Mbps DSSS
7/28/2019 802.11 standards1
7/10
7AITA\SWBU\CWNA\08
802.11b Scalability
Blue = 11 Mbps
Green = 11 Mbps
Red = 11 Mbps
Total Bandwidth = 33 Mbps!!!
7/28/2019 802.11 standards1
8/10
8AITA\SWBU\CWNA\08
Comparing the Technologies
802.11a Data Rates
Modulation withSub Channels
Modulation withSub Channels
BPSKBPSK
Data Rate Per
Subchannel(Kbps)
Data Rate Per
Subchannel(Kbps)
BPSKBPSK
QPSKQPSK
125125
187.5187.5
250250
QPSKQPSK 375375
Total Data Rate(Mbps)
Total Data Rate(Mbps)
66
99
1212
1818
16QAM16QAM
16QAM16QAM64QAM64QAM
500500
75075010001000
64QAM64QAM 11251125
2424
36364848
5454
7/28/2019 802.11 standards1
9/10
9AITA\SWBU\CWNA\08
802.11a Access Point Coverage
OFDMOFDM54 Mbps54 Mbps
48 Mbps48 Mbps
36 Mbps36 Mbps
24 Mbps24 Mbps
18 Mbps18 Mbps
12 Mbps12 Mbps
09 Mbps09 Mbps
06 Mbps06 Mbps
7/28/2019 802.11 standards1
10/10
10AITA\SWBU\CWNA\08
802.11a Scalability (Indoor UNII-1 and 2)
54 Mbps
54 Mbps
54 Mbps
Total Bandwidth = 432 Mbps!!!
8 non-overlapping
channels
54 Mbps
54 Mbps
54 Mbps
54 Mbps
54 Mbps
Recommended