05. Wireless LAN

05. Wireless LAN - 1 Wireless LAN Communication Networks ©...

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Unformatted text preview: 1 Wireless LAN Communication Networks © Kang Xi, Polytechnic Institute of NYU 2 Overview of Wireless LAN ¡ Main Advantage: ¢ Freedom ¡ Main Challenges: ¢ Shared transmission medium ¢ Transmission impairments Communication Networks © Kang Xi, Polytechnic Institute of NYU 3 Infrared, Optics, Radio ¡ Infrared ¢ Huge spectrum, potential high data rate ¢ Line-of-sight ¡ Free space optics ¢ At the speed of light ¢ Line-of-sight ¡ Radio (narrow/wide band) ¢ Real freedom ¢ High speed ¢ Limited frequency resource Communication Networks © Kang Xi, Polytechnic Institute of NYU 4 Wireless LAN -- IEEE 802.11 ¡ Replacement for Ethernet: ¢ wireless channel ¢ Frequency band: unlicensed radio spectrum of 2.4GHz and 5GHz ¡ Data rates: ¢ 1, 2, 5.5, 11, 54 Mbps ¡ Range: transmission power up to 100mW ¢ indoor: 20 - 25 meters ¢ outdoor: 50 - 100 meters Communication Networks © Kang Xi, Polytechnic Institute of NYU 5 IEEE 802.11 Protocols ¡ IEEE 802.11b: 5, 11Mbps ¡ IEEE 802.11a: 6, 9, 12, 18, 24, 36, 48, 54Mbps ¡ IEEE 802.11g: 54Mbps ¡ IEEE 802.11i: security ¡ IEEE 802.11f: Inter Access Point Protocol ¡ IEEE 802.11e: Quality of Service enhancement Communication Networks © Kang Xi, Polytechnic Institute of NYU 6 Basic Service Set (BSS) Architecture ¡ Infrastructure Mode ¢ No direct communication is allowed between stations ¢ An access point (AP) communicate with all the stations and relay messages ¡ Ad Hoc Mode ¢ Peer-to-peer direct communication Communication Networks © Kang Xi, Polytechnic Institute of NYU 7 Extended Service Set ESS: a set of BSSs interconnected by a distribution System – ESS and all of its stations appear to be in a single MAC layer – AP communicate with each other to forward traffic – Station mobility within an ESS is invisible to the higher layers Communication Networks © Kang Xi, Polytechnic Institute of NYU 8 Example Access Point + Router Communication Networks © Kang Xi, Polytechnic Institute of NYU 9 Protocol Stacks 802.3 PHY 802.3 MAC LLC IP 802.11 PHY 802.11 MAC Communication Networks...
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This note was uploaded on 11/02/2010 for the course EE 136 taught by Professor Kang xi during the Spring '10 term at NYU Poly.

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05. Wireless LAN - 1 Wireless LAN Communication Networks ©...

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