Energy Saving Dynamic Relaying Scheme in Wireless Cooperative Networks Using Markov Decision Process

Energy saving becomes one of the most important design considerations in wireless cooperative networks which are composed of nodes typically powered by batteries that can supply only a finite amount of energy. In this paper, we propose a dynamic relaying scheme based on relay selection and physical-layer power control with the objective of minimizing the energy consumption for data transmission. We first develop a mathematical model for the cooperative relaying and analyze the total battery energy consumption to forward a symbol. Based on the analytic results and Markov channel model, we formulate the optimization problem that minimizes total average energy consumption as a Markov decision process, with which we can decide an optimal relay and the transmission power distributely. In the proposed scheme, the relay selection process and cooperation mode starts only when the direct transmission between source and destination node failed, which is energy efficient from a network sense. Numerical simulation show that the proposed scheme achieves significant energy savings.