— Energy efficient operation is of paramount importance for battery-powered wireless nodes. In an effort to conserve energy, standard protocols for WLANs have the provision for wireless nodes to “sleep” periodically. In this paper we first consider the problem of optimizing the timing and duration of the sleep state of a single wireless node (or user) with the objective of minimizing power consumption with respect to a QoS constraint. The QoS parameter that we have focused on is average packet delay. Using a Dynamic Programming formulation, coupled with a duality argument, we solve the optimization problem numerically. Using a branching process analysis, we were able to derive closed form expressions for the optimal sleep duration, as well as the associated minimal rate of power consumption. We show that the optimal power cost derived from the 1-user Dynamic Programming (DP) formulation provides a lower bound to the average power consumption for the multiple user case. To gain be...
Mahasweta Sarkar, Rene L. Cruz