Energy management in wireless sensor networks

Abstract

This chapter is concerned with system-level energy management in wireless sensor networks. The network is designed to conduct certain tasks that require information from individual sensors to be sent to a base station. Sensors cease functioning when they deplete their energy reserves or may fail abruptly due to random malfunctions. Sensor selection refers to the number of times sensors are interrogated, while sensor scheduling refers to the sequence in which these interrogations are conducted. A sensor management layer that isolates the system objectives from selection/ scheduling is proposed. In the metric of expected network lifetime, it is shown that sensor selection reduces to integer linear programming (ILP). Sensor scheduling is necessary only when random sensor failures are considered or when the task definition is not stationary. Some general principles emerge. If all sensors are equally reliable, the optimal policy is to use the most energetic sensors first. If all sensors are equally energetic, the optimal policy is to use the least reliable sensor first.