An Efficient Relay Selection Protocol for Cooperative Wireless Sensor Networks

In this paper, we propose a novel and efficient relay selection protocol based on geographical information for cluster-based cooperative wireless sensor networks (WSNs). Multihop transmission is realized by concatenation of single cluster-to-cluster hops, where each cluster-to-cluster scheme forms the simplified cooperative network that consists of a single source- destination pair and a set of available relays. With the relay selection mechanism, the source in each cluster-to-cluster hop selects an optimum relay to execute the cooperative diversity transmission via the simple adaptive decode-and-forward (DF) strategy. The proposed relay selection protocol is designed for minimum symbol error probability (SEP) at the destination by utilizing only geographical information among nodes as selection criteria. In particular, such geographical information is often available during network initialization, and its state required to be maintained is minimum. Therefore, the proposed protocol can efficiently perform relay selection without complicated procedures that examine out the optimum relay by channel estimations, and hence it reduces significantly the computational complexity and is applicable to a fast-varying environment. Simulation results demonstrate the proposed relay selection protocol can efficiently improve the system performance and outperform the random relay selection protocol in terms of symbol error probability.