Heterogeneous WiFi 802.11 a/b/g/n Sarah El-Helw Jennifer Ogunlowo

Introduction Evaluate performance of Wi-Fi standards under multiple network conditions. 802.11n provides greater throughput and more range. Wi-Fi performance is easily affected by various interference. 802.11b 2.4 – 5 GHz unlicensed radio spectrum Delivers 11 MB/s Uses DSSS (Direct Sequence Spread Spectrum) 802.11a 5 – 6 GHz Delivers 54 MB/s Uses OFDM (Orthogonal Frequency-Division Multiplexing) 802.11g 2.4 – 5 GHz range Uses OFDM Prof. Ghassan AlRegib Summer 2007 ECE 3076

Milestones Background study on 802.11a/b/g/n. Set-up basic topology and run traffic tools. Compare different technologies under multiple network conditions. Evaluate performance of multiple technologies under the same vicinity Present analysis of results.

Preliminary milestones Obtained research on Wi-Fi standards. Set-up topology between wired server and wireless client. Transferred packets between client and server using Iperf. Analyzed network performance indoors, outdoors, and microwave interference.

Co-existence of multiple technologies 802.11g & n

Co-existence of multiple technologies 802.11 a & b

Outdoors Results Selected greater distances to measure throughput ~ 150ft, 250ft. Used additional tool, NetStumbler, to analyze signal strength over various distances. Wired server indoors partitioned by glass, wireless client outdoors. Observed presence of 32 additional AP’s.

~150ft (running TCP)

~150 ft (running UDP)

~250ft (running TCP)

NetStumbler Detects the presence of various access points. Displays the signal strength in dBm against time. Shows valid signal strength based on wireless cards in client machines. Taller the green plot, the stronger the signal.

NetStumbler Signal quality evaluation : Decreased signal strength with increased distance yields low throughput.

~300 ft for 802.11n 802.11n AP was only active AP for distance of ~300ft. Signal lost over distance greater than 300ft.

non -LOS Experiments performed with wired server in one room and wireless client in other room, separated by a wall.

Summary and Future Work 802.11 a and 802.11 gSRX were superior to b and g performance. 802.11a preformed best under most usual settings, while 802.11 gSRX was the best at a great distance. Wi-Fi performance can be affected by various interference like microwave ovens, AP’s. The future work would be to obtain an 802.11n router once they’ve completely been released, and compare it with the current network performance.