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802.11 Standards

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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

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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

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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

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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

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802.11b Access Point Coverage

1 Mbps DSSS

5.5 Mbps DSSS

11 Mbps DSSS

2 Mbps DSSS

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802.11b Scalability

Blue = 11 Mbps

Green = 11 Mbps

Red = 11 Mbps

Total Bandwidth = 33 Mbps!!!

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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

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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

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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