Power management modeling and optimal policy for IEEE 802.11 WLAN systems

Power saving is a critical issue for almost all kinds of portable devices as the lifetimes of wireless devices running on batteries are limited by their energy source capacity. Among portable devices, the IEEE 802.11 based products have become widespread in recent decades. In this paper, we proposed an optimal power management scheme which complies with the power saving mode (PS mode) deployed in IEEE 802.11 based networks to help the system consume power efficiently. A Markov decision process (MDP) approach is used to model the power tuning process. The listen interval of a mobile station is adjusted according to our proposed power management policy in order to optimize the power lifetime of a portable device while maintaining the link quality in terms of frame loss and delay. The numerical results are compared with various power management schemes including a noncontrolled scheme and fixed listen interval schemes. Simulations are conducted by network simulator, ns-2, to evaluate the performance under different traffic conditions.