Summary: Appears in Proceedings of 8th International Conference on Principles of Distributed Systems (OPODIS 2004)
Sentries and Sleepers in Sensor Networks
Mohamed G. Gouda½, Young-ri Choi½, and Anish Arora¾
Department of Computer Sciences, The University of Texas at Austin,
1 University Station C0500, Austin, TX 78712-0233, U.S.A.
gouda, yrchoi @cs.utexas.edu
Department of Computer and Information Science, The Ohio State University,
2015 Neil Avenue, Columbus, OH 43210-1277, U.S.A.
Abstract. A sensor is a battery-operated small computer with an antenna and a sensing board that can sense
magnetism, sound, heat, etc. Sensors in a network can use their antennas to communicate in a wireless fashion
by broadcasting messages over radio frequency to neighboring sensors in the same network. In order to lengthen
the relatively short lifetime of sensor batteries, each sensor in a network can be replaced by a group of ̉ sen-
sors, for some ̉ 2. The group of ̉ sensors act as one sensor, whose lifetime is about ̉ times that of a regular
sensor as follows. For a time period, only one sensor in the group, called sentry, stays awake and performs all
the tasks assigned to the group, while the remaining sensors, called sleepers, go to sleep to save their batteries.
At the beginning of the next time period, the sleepers wake up, then all the sensors in the group elect a new
sentry for the next time period, and the cycle repeats. In this paper, we describe a practical protocol that can