Dynamic sensor activation for maximizing network lifetime under coverage constraint

Wireless sensor networks consist of a large number of sensors equipped with limited energy and processing capabilities. They are deployed in a field to measure physical variables or detect events. In critical surveillance applications, sensors are used to monitor a geographical area and usually a full, or high, area coverage is required as a Quality-of-Service (QoS) parameter. In dense networks, sensors detection ranges usually overlap. Therefore, only a covering subset of sensors can be turned on while other sensors are put in a very low-power Sleep state. In this paper, we address the problem of maximizing the sensor network lifetime under area coverage constraint. For that, we propose a mechanism that dynamically activates an optimal covering subset of sensors, based on residual energies. We first model this problem as an Integer Linear Programming (ILP) problem that we resolve using CPLEX. Then, we propose a greedy heuristic to tackle the exponentially-increasing processing times of the exact solution. We show that the proposed heuristic provides for acceptable solutions while having a polynomial O(N²) complexity, suitable for large-scale networks.