Distributed Relay Selection for Two-Way Relaying Networks Based on Power Conservation

In order to improve the power efficiency and extend the lifetime of the two-way amplify-and-forward (AF) relaying system, this paper proposes a distributed relay selction scheme based on relay power conservation. The closed-form solution of the the optimal power allocation based on total power minimization under the signal-to-noise ratio (SNR) constraints is derived, and the relay which requires the minimum transmit power among all relays is selected to assist two-way transmissions. The scheme can be performed in a distributed manner which only requires user-relay channel state information. Simulation results demonstrate that the proposed scheme can significantly decrease the relay power consumption.