An Integrated Approach to Energy-Aware Medium Access for Wireless Sensor Networks

This paper addresses the design of distributed medium access control (MAC) protocols for wireless sensor networks under the performance measure of network lifetime. Integrated in the design of MAC schemes are two key physical-layer parameters: the channel state and the residual energy of each sensor. The individual and collective impacts of incorporating these parameters in MAC design on network lifetime are studied. We show that a lifetime-maximizing protocol should dynamically trade off the channel state information (CSI) with the residual energy information (REI) according to the age of the network. Specifically, lifetime-maximizing protocols should be more opportunistic by prioritizing sensors with better channels for transmission when the network is young and more conservative by favoring sensors with more residual energies when the network is old. Following this general design principle, we propose a dynamic protocol for lifetime maximization (DPLM) that exploits local information of both channel state and residual energy. Analytical and simulation results are provided to demonstrate the dynamic property and the asymptotic optimality of DPLM: its relative performance loss as compared to the performance limit defined by the optimal centralized protocol using global CSI and REI diminishes as the initial energy of each sensor increases.