Sleep scheduling and lifetime maximization in sensor networks: fundamental limits and optimal solutions

摘要

Energy efficiency is a very critical consideration in the design of low cost sensor networks, which typically have fairly low node battery life. This raises the need for providing periodic sleep cycles for the radios in the sensor nodes. Keeping sensors in sleep state also implies that node to sink communication incurs certain delays and there exists a threshold on the duty cycling for the communication delay to be bounded, giving rise to an upperbound on the lifetime of the network i.e., the time until at least one node in the network is able to communicate its sensed data to the sink. This paper aims at establishing tight analytical bounds on the sleeping probabilities of nodes and on the achievable lifetime of wireless sensor networks in a very generic setting. Bounds on the sleeping probability need to be satisfied for proper network functionality. Further, an energy efficient deployment scheme is suggested wherein the battery power depletion is fairly uniformly deployed throughout the network. This scheme makes use of the availability of low power auxiliary channel listening radio. With this scheme, we shown that an improvement in lifetime by a factor of O(/spl radic/log n) over uniform distribution of nodes is achievable, where n is the number of nodes in the network. We also show that the throughput capacity of the network is also improved by the same factor. We show also that the maximum lifetime of the network is bounded above by O(n/sup 3/2///spl radic/log n). Further, the accuracy of our analysis is verified by the simulation results presented.