Energy-efficient relay selection and power allocation scheme in AF relay networks with bidirectional asymmetric traffic

This paper proposes a joint relay selection and power allocation scheme for bidirectional asymmetric traffic to minimize the weighted energy consumed per bit transmitted. The scheme can be applied to both one-way and two-way Amplify-and-Forward (AF) relay networks. In the scheme, close-form solutions for energy efficient power allocation are derived with perfect channel state information at each relay. Then the relay consuming the least energy is chosen by the sources. On the basis of the proposed scheme, we characterize the energy consumption for training and power allocation information exchange between each relay and source. Simulation results demonstrate that the proposed scheme can achieve high energy efficiency when proper number of relays is deployed. It is also shown the two-way relaying provides substantial energy saving gains compared with the one-way relaying.