An efficient heuristic for placement, scheduling and routing in wireless sensor networks

In this paper we consider the differentiated coverage problem for heterogeneous sensor networks over a finite planning horizon consisting of discrete time intervals. The goal is to determine optimal locations of sensors and sinks, activity schedules of the deployed sensors, and sensor-to-sink data routes subject to coverage, flow conservation, energy consumption and budget constraints with the objective of maximizing the network lifetime. We first give a mixed-integer linear programming formulation. Since this formulation is difficult to be solved exactly even for small instances, we propose a heuristic that first finds connected sensor sets with minimum cost satisfying the coverage constraint, and then determines optimal sensor-to-sink data routes with optimal flow quantities maximizing the lifetime of the sensor sets. Computational experiments performed on various test instances indicate that the heuristic is very efficient and quite accurate.