Maintaining Sensing Coverage and Connectivity in Large Sensor Networks

Abstract

Abstract — In this paper, we address the issues of maintaining sensing coverage and connectivity by keeping a minimal number of sensor nodes in the active mode in wireless sensor networks. We investigate the relationship between coverage and connectivity by solving the following two sub-problems. First, we prove that if the radio range is at least twice of the sensing range, a complete coverage of a convex area implies connectivity among the working set of nodes. With such a proof, we can then focus only on the coverage problem. Second, we derive, under the ideal case in which node density is sufficiently high, a set of optimality conditions under which a subset of working sensor nodes can be chosen for full coverage. Based on the optimality conditions, we then devise a decentralized and localized density control algorithm, Optimal Geographical Density Control (OGDC), for density control in large scale sensor networks. Ns-2 simulation show that OGDC outperforms the PEAS algorithm [32], the hexagon-based GAFlike algorithm, and the sponsor area algorithm [28] with respect to the number of working nodes needed (sometimes at a 50% improvement), and achieves almost the same coverage as the algorithm with the best result. I.