Joint Relay Selection and Power Allocation for Two-Way Relaying with Physical Layer Network Coding

We consider a two-way relay (TWR) network with multiple relays, where the relays adopt physical layer network coding based on decode-and-forward. A joint relay selection and power allocation (RS-PA) scheme is proposed to improve the symbol error probability (SEP) of the TWR network using BPSK modulation under the total power constraint. For the proposed scheme and the benchmark scheme performing RS without PA, the average SEP of the TWR network is derived analytically and confirmed with simulation results. It is shown that the proposed scheme provides an asymptotic SNR gain of about 1.76 dB over the benchmark scheme at the same diversity order.