An Energy Efficient Relay Selection Algorithm for Clustered Wireless Sensor Networks

In this paper we propose an energy-efficient relayselection algorithm for clustered Wireless Sensor Networks(WSNs). In contrast to conventional multi-hop transmissionschemes adopted in clustered WSNs, where only cluster heads(CHs) participate in the transmission, in our method the relay isselected from a set of candidate nodes within the sourcetransmission range, subject to predefined desired transmissionpower at the source and the relay. The fundamental of thismethod is to forward the source signal using the node whichminimizes the end-to-end total path distance, such that the totalenergy cost per bit is reduced at the relay and at the source.Thus, the node that satisfies the signal-to-noise ratio (SNR)distance-based threshold of both links participates in thetransmission. Taking into consideration the circuit energy cost,the modulation strategy and its impact on energy cost areinvestigated and the optimal choice of the number of bits persymbol is considered to optimize the total energy cost pertransmission. The proposed method is shown to be more energyefficient compared to the traditional multi-hop transmissionand random relay selection in terms of energy cost for a targetbit error rate at the destination. Additionally, the proposedmethod also outperforms both methods in terms of the networklifetime.