To Sleep or Not to Sleep: a Microscopic Study of Power Management in IEEE 802.11 Wireless Networks

 

Abstract

IEEE 802.11 power saving mode (PSM) is one of the most popular techniques in wireless LANs and multi-hop wireless networks to coordinate the power states of communication devices. In IEEE 802.11 PSM, power management decisions to wake up or put wireless devices to sleep states are made periodically every beacon interval. In this talk, we demonstrate via a rigorous analytical model (the result of which is corroborated by simulation results) that such a periodic structure together with its signaling overhead leads to both energy and bandwidth under-utilization. We then present SIMPA, a new power management protocol based on IEEE 802.11 PSM, to decouple the power management decision points and the beacon intervals, so as to allow power control at a finer granularity. In SIMPA, wireless devices can switch to the low-power states inside a beacon interval or extend their active states beyond one beacon interval. A comprehensive simulation study in both the single hop wireless LANs without AP support and the multi-hop wireless networks demonstrates that as compared to IEEE 802.11 PSM, SIMPA can effectively reduce energy consumed under light to medium traffic loads and retain the network capacity for data transport at high traffic loads.

Bio of the Speaker

Rong Zheng is presently a post-doc research associate at the University of Illinois at Urbana-Champaign. Rong defended her Ph.D. dissertation in Dept. of Computer Science, University of Illinois at Urbana-Champaign in Dec. 2003 and earned her M.S. and B.S. in Electrical Engineering in May 1998 and June 1996 at Tsinghua University, P.R. China. Rong's research interests span networking and embedded systems, in particular energy-efficient designs in wireless LAN networks and sensor networks, localized algorithms in large-scale distributed systems, hybrid simulation tools for computer networks. Her Ph.D. thesis is entitled "Design, Analysis and Empirical Evalution of Power Management in Multi-hop Wireless Networks". In her Ph.D. thesis, Rong designed on-demand power management framework and asynchronous wakeup protocol for multihop wireless networks. She also developed queuing theoretical models to quantify the trade-off between performance and energy efficiency for various power management schemes.

 

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