Exploiting sensor spatial redundancy to improve network lifetime [wireless sensor networks]

One of the most critical issues in wireless sensor networks is represented by the limited availability of energy within network nodes; thus, making good use of energy is a must to increase network lifetime. We define as network lifetime the period from the time instant when the network starts functioning till the network runs, satisfying its quality requirements, i.e., a given level of coverage in the area of interest is guaranteed. To maximize system lifetime, we exploit sensor spatial redundancy by defining sub-sets of sensors active in different time periods, to allow sensors to save energy when inactive. Two approaches are presented: the first one, based on mathematical programming techniques, must run in a centralized way; whereas the second one is based on a greedy algorithm, aimed at a distributed implementation. To assess their performance and provide guidance to network design, the two approaches are compared by varying several network parameters.