Performance Analysis of Asymmetric Two-Way Relay Channels with Physical-Layer Network Coding

Up to now, most of the researches about physical-layer network coding (PNC) are based on symmetric two-way relay channels. In this paper, we mainly study PNC in asymmetric two-way relay channels with Rayleigh fading channels and classify the systems into five asymmetric cases. So as to describe the asymmetric cases, we will introduce the asymmetric factors. We simulate the BER performance of PNC for symmetric and asymmetric cases with asymmetric factors fixed. After that we analyze the BER performance of PNC with one of the asymmetric factors is variable when two channels are relatively unreliable. Finally, we give the conditions that one kind of asymmetric scenario transforming to other kind. Also, in the matter of anti-noise performance, uplink asymmetry is the worst case and the phase asymmetry-downlink is the best case.