self-management in chaotic wireless deployments a. akella, g. judd, s. seshan, p. steenkiste...
TRANSCRIPT
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 l
evels– Transmissions rates of APs and clients.
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
• 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