Optimal power allocation and relay selection in two-way multi-relay cooperative communication

In this paper, we investigate the power allocation in two-way multi-relay assisted cooperative network in which the relays operate in decode-and-forward (DF) protocol. In the proposed method for choosing the best relay there is no need for channel state information (CSI) in transmitter terminals. Based on the minimum of the channel coefficients between source-relay and relay-destination, we choose the relay which its associated minimum coefficient is maximum among all the relays. We derive a closed form expression for bit error rate (BER) in cooperative networks with two-way relays according to our proposed algorithm for relay selection. Optimum power allocation between sources and selected relay yields to almost 2dB improvement in BER performance.