Minimizing Power Consumption in Sensor Networks with Quality of Service Requirement

Minimizing energy and power consumption in wireless sensor networks is critical in extending the lifetime of the network. In this paper we consider efficient power/rate allocation strategies with certain quality of service constraints. The transmission rate achieved and the power used are related by a power-rate function for a given channel state. Specifically, two problems are formulated, one seeking to minimize the average power consumption subject to an average rate constraint, while the other seeking to maximize the average data rate subject to an average power constraint. We consider two scenarios of power management of a wireless node/device. In the first case the node always stays on thereby consuming power in circuitry as well as in transmission/reception. In the second case the node turns its transceivers off from time to time, and by doing so while avoiding circuitry power during sleep periods, consumes power in switching from the off state to the on state. For both problems stationary and deterministic policies are considered. We first study the optimum power/rate allocation when the nodes are always active and provide algorithms that produce optimal solutions to these two problems. We then consider a two-state channel model and study optimal joint power allocation and sleep scheduling for both problems.