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This presentation, adapted from a Mobicom 2005 talk by Glenn Judd, discusses the rapid proliferation of wireless access points (APs) across consumer environments such as malls and airports. It highlights the chaotic nature of these unplanned deployments and their negative impact on end-user performance. Key findings include the necessity for automated channel selection, the influence of transmit power on performance, and initial strategies for mitigating adverse effects. The presentation concludes with reflections on the critical need for effective management to enhance user experience in high-density wireless environments.
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Self-Management in Chaotic Wireless Deployments Aditya Akella, Glenn Judd, Srini Seshan, Peter Steenkiste Presented by: Farhana Ashraf Adapted from Mobicomm 2005 presentation by Glenn Judd
Wireless Proliferation • Sharp increase in deployment • Airports, malls, coffee shops, homes… • 4.5 million APs sold in 3rd quarter of 2004!
Change in Wireless Landscape UNPLANNED and UNMANAGED PLANNED and MANAGED CHAOTIC NETWORK!!!
Outline • Quantify characteristics of chaotic wireless deployment • Impact on end-user performance • Initial work on mitigating negative effects • Conclusion
50 m 1 1 2 1. AP Degree [Place Lab] City #AP Max.degree A B C
Most users don’t change default channel Channel selection must be automated 2. Unmanaged APs [WifiMaps] Channel % AP
3. AP Management Support [Wardrive] Vendor % AP • Major vendors dominate • Incentive to reduce “vendor self interference”
Outline • Quantify characteristics of chaotic wireless deployment • Impact on end-user performance • Initial work on mitigating negative effects • Conclusion
Impact on Performance [Globosim Trace-driven simulation on Wardrive Data set] • 20 APs in topology • Each AP has D clients • Each client runs HTTP/FTP workloads • Vary stretch ‘s’ scaling for inter-AP distances
Impact on HTTP Performance 3 clients per AP. 2 clients run FTP sessions. All others run HTTP.300 seconds 5s sleep time Degradation 20s sleep time Max interference No interference
Optimal Channel Allocation vs.Optimal Channel Allocation + Tx Power Control Channel Only Channel + Tx Power Control
require: mediumUtilization <= 1 txPower determines range dclient, txPower determines rate dclient dmin Impact of Joint Transmit Power and Rate Control Objective: given <load, txPower, dclient> determine dmin APs
Impact of Transmit Power Control • Minimum distance decreases dramatically with transmit power • High AP densities and loads requires transmit power < 0 dBm • Highest densities require very low power can’t use 11Mbps!
Outline • Quantify characteristics of wireless deployment • Impact on end-user performance • Initial work on mitigating negative effects • Conclusion
Power and Rate Selection Algorithms • Fixed-Power Rate Selection • Auto Rate Fallback: ARF • Based on probe • Estimated Rate Fallback: ERF • Based on SNR DATA If ACK fails, Decrease rate If success, Increase rate B A ACK
Power and Rate Selection Algorithms • Adaptive-Power Rate Selection • Sender reduces power as long as rate is not reduced • Extension to Fixed-Power Rate selection • Power Auto Rate Fallback: PARF • Power Estimated Rate Fallback: PERF
Lab Interference Test Topology Results
Conclusion • Significant densities of APs in many metro areas • Many APs not managed • High densities could seriously affect performance • Static channel allocation alone does not solve the problem • Transmit power along with adaptive rate control effective at reducing impact
