Energy-Efficient Barrier Coverage in WSNs with Adjustable Sensing Ranges

Energy-efficient barrier coverage is an important issue in wireless sensor networks. In this paper we study the problem of how to maximize the lifetime of a barrier, where sensors have adjustable sensing ranges. In our approach, each node is divided into some virtual sub-nodes according to the available sensing ranges. For small-scale sensor networks, we construct a barrier coverage graph where a link exists between two sub-nodes in two different nodes, if their sensing ranges overlap. We propose to use a linear programming optimization method based on the exhaustive search of all possible barriers in the constructed graph to find the optimal barriers and their respective operation times. For large-scale sensor networks, we propose two distributed heuristics: one is to randomly select, from its neighboring sub-nodes, a next sub-node to construct barriers; another is to greedily select a next sub- node to best match the lifetime of the barrier constructed before choosing this sub-node. Simulation results show that compared with the randomized one, the greedy scheme can achieve longer lifetime and lower message overhead.