Self-Management in Chaotic Wireless Deployments A. Akella, G. Judd, S. Seshan, P. Steenkiste Carnegie Mellon University

Outline INTRODUCTION IMPACT ON END-USER PERFORMANCE TRANSMISSION POWER AND RATE SELECTION PERFORMANCE EVALUATION CONCLUSION

INTRODUCTION Chaotic Wireless Networks –Unolanned –Unmanaged Suffer from –serious contention –poor performance –security problems

INTRODUCTION To improve end-user performance –Automatically manage the transmission power levels –Transmissions rates of APs and clients.

INTRODUCTION Power control algorithm called –Power-controlled Estimated Rate Fallback (PERF)

IMPACT ON END-USER PERFORMANCE Simulation GloMoSim Topology

IMPACT ON END-USER PERFORMANCE Simulation assumptions ： –Each node on the map is an AP –Each AP has D clients with 1 ≤ D ≤3 –Clients are within 1 meter from their AP and they don ’ t move –All APs transmit on channel 6 –All APs use fixed power level of 15dBm –All APs transmit at fixed rate 2Mbps –RTC/CTS is turned off (default settings)

IMPACT ON END-USER PERFORMANCE http with thinking time by Poisson distribution with mean equal to 5s or 20s Comb-ftpi, i clients run FTP transmission Results: –HTTP ： 83.3 Kbps for 5s 24.5 Kbps for 20s –FTP ： 0.89 Mbps for 300s

IMPACT ON END-USER PERFORMANCE

Two simple mechanisms on mitigating interference –Use an optimal static allocation of non- overlapping channels –Reduce the transmit power levels

IMPACT ON END-USER PERFORMANCE Non-overlapping channel assignment

IMPACT ON END-USER PERFORMANCE Three non-overlapping channels Only channel 6

IMPACT ON END-USER PERFORMANCE

Transmit power control

IMPACT ON END-USER PERFORMANCE Managing power control and using static allocation of non-overlapping channels can reduce the impact of interference on performance

TRANSMISSION POWER AND RATE SELECTION PARF: Power-controlled Auto Rate Fallback –Based on ARF It Attempts to elect the best transmission rate –adding low power states above the highest rate state. –Power is repeatedly reduced until the lowest level is the transmission failed threshold is reached

TRANSMISSION POWER AND RATE SELECTION PERF: Power-controlled Estimated Rate Fallback –Based on ERF(SNR+ERF): It uses path loss information to estimate the SNR with which each transmission will be received –The transmission power is reduced to estimatedSNR = decisionThreshold + powerMargin

PERFORMANCE EVALUATION

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CONCLUSION Power control and rate adaptation can reduce interference Reduce power as long as transmission rate was unaffected.