Energy efficient hybrid ARQ scheme for cooperative communication in underwater acoustic sensor networks

Abstract

In this article, we present an analytical model to compute the energy efficiency of underwater acoustic sensor networks (UASNs) in deep and shallow water scenarios. Acoustic parameters such as, distance-dependent usable bandwidth, acoustic fading and different propagation characteristics of underwater channel are taken into account in this model. Further, we propose a hybrid automatic repeat request scheme for cooperative communication (HARQ-CC) in UASNs. It combines Reed-Solomon codes and selective retransmissions in cooperative communication to optimise the energy efficiency. The analytical results clearly indicate that HARQ-CC can improve the energy efficiency when the source and destination nodes are separated by larger distances. We propose an optimisation algorithm to maximise the energy efficiency by adaptively adjusting the modulation level and packet size as a function of the distance between the source and destination nodes. It is observed that by using the optimisation algorithm, the energy efficiency has been further improved for HARQ-CC, leading to highly reliable and energy efficient HARQ-CC scheme for UASNs.