Constructing Minimum Relay Connected Sensor Cover in Heterogeneous Wireless Sensor Networks

Energy efficiency is an important problem in wireless sensor networks. In this paper, we consider the energy efficiency problem in a heterogeneous wireless sensor network which consists of energy-constrained sensor nodes and resource-rich relay nodes. We firstly formulate the minimum relayconnected sensor cover (MRCSC) problem for heterogeneous sensor networks. The purpose of this problem is to activate as small number of sensor nodes as possible while satisfying two requirements simultaneously: (1) all active sensor nodes must cover the task area completely; (2) all active sensor nodes must be relay connected to the backbone network formed by all relay nodes. Then we propose a distributed algorithm to construct the MRCSC of a randomly deployed heterogeneous sensor network. The basic idea of this algorithm is to construct the minimum sensor cover firstly and then ensure its relay connectivity afterwards. To construct the minimum sensor cover, we present a principle for selecting sensing nodes based on the triangle lattice. In order to guarantee the relay connectivity of selected sensing nodes, we propose verification and reinforcement procedures. Extensive simulations show that the proposed algorithm can achieve the coverage performance comparable to OGDC algorithm and effectively improve the relay connectivity of the sensor cover with small number of additional sensor nodes.