1Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario, Canada
2Department of Electrical and Computer Engineering, and Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois
Wireless sensor networking is an emerging technology that has a wide range of potential applications including environment and habitat monitoring, smart spaces, health monitoring, traffic control, and the like. Such a network normally consists of a large number of nodes distributed in space, each of which may be equipped with one or more sensors, a radio transceiver, a microcontroller, and an energy source, usually a battery. In many applications, it is often very difficult to change or recharge batteries for these nodes1. Thus, prolonging the network lifetime by efficiently using the battery energy is a critical issue in the operation of wireless sensor networks. Generally, in sensor networks, wireless communications consume much more energy compared to the other node activities. Developing much more energy-efficient communications schemes will certainly lead to significant energy savings .
In many applications of sensor networks, nodes remain largely inactive for a long time but become suddenly active when something ...