Energy-efficient relay selection for QoS provisioning in MIMO-based underwater acoustic cooperative wireless sensor networks

In recent years, the MIMO-based underwater acoustic (UWA) wireless sensor networks have attracted significant research attention because of its wide and critical applications in marine research, oceanography, marine commercial operations, offshore oil industry, and defense systems. The cooperative-communications-based wireless relay networks have been widely cited as a very efficient technique to enhance the transmission and lifespan performances of the wireless networks. However, how to make the energy-efficient relay selection in the MIMO-based UWA wireless sensor networks, particularly under the harsh underwater wireless environments with the stringent power supply constraint, have been not well understood, neither thoroughly studied. To overcome the above problems, in this paper we propose the optimal relay selection scheme to minimize the energy consumption while guaranteeing the quality of service (QoS) of each link over the MIMO-based UWA cooperative wireless sensor networks. We use the Finite-state Markov chain to model the UAW channel. Moreover, we also incorporate MIMO multiplexing-gain and diversity-gain techniques, as well as residual relay energy in the relay selection process. We implement our proposed optimal relay selection scheme by the linear programming (LP) technique. We conduct the simulations to validate and evaluate our proposed scheme, showing its superlatives over the other existing schemes.