Performance of physical-layer network coding in asymmetric rayleigh fading two-way relay communication systems

Physical-layer Network Coding (PNC) has drawn so much attention of wireless communication researchers. However, most of the studies focused on symmetric Two-Way Relay Communication (TWRC) systems. In order to analyze the performance of PNC in asymmetric scenario, in this study, we classify TWRC systems with Rayleigh fading channels into five asymmetric cases according to different poor channel allocation. In each symmetric and asymmetric case, we provide the detailed signal transmission and processing progress. Then we simulate the Bit Error Rate (BER) performance of PNC either in symmetric or asymmetric cases. From the results, we know that the Phase Asymmetry-Uplink (PA-U) case is the worst and Downlink Channel Asymmetry (DCA) case is the best among the five asymmetric cases. We also conclude that poor uplink channels will provide more severe effect to the performance degradation caused by system asymmetry than poor downlink ones.