Minimizing Energy Consumption for Lossless Data Gathering Wireless Sensor Networks

Energy minimization in wireless sensor networks is a key issue, particularly in order to maximize the lifetime of nonserviceable battery powered devices in the field. In this paper, we propose a new energy consumption model that allows allocation of variable transmit power and data compression/transmission rate to each sensor node. In contrast to previous work, our model captures both the cost of wireless transmission as well as the cost for a node to be in an active mode during transmission. This is an important and non-trivial consideration, as higher data rates require greater transmit power for reliable wireless transmission, however this reduces the duration for which the node must be in active mode. Based on this new model, we consider minimization of the total energy cost of lossless data gathering by using joint power and rate allocation under rate and capacity constraints. We show how the rate and power allocation problems are coupled in general, and we provide a convex optimization formulation for the resulting joint optimization problem. We present a special case for which power allocation separates from the rate allocation problem, namely when the cost of being active dominates. For this special case we obtain a simple characterization of the optimum power and rate allocation strategy. Simulation results are given in line with the theoretical analysis.