Combined orthogonal physical-layer network coding over fading two-way relay channels

This paper proposes a new physical-layer network coding (PNC) scheme, named combined orthogonal PNC (COPNC), for fading two-way relay channels. The scheme is based on orthogonal PNC (OPNC). In the scheme, the two source nodes employ orthogonal carriers, and the relay node makes an orthogonal combining of the two information bits rather than exclusive or (XOR), which is employed in most PNC schemes. The paper also analyzes the bit error rate (BER) performance of PNC, OPNC, and COPNC for Rayleigh fading model. Simulation results for Rayleigh and Nakagami-m fading channels show that COPNC can provide outstanding BER performance compared with PNC and OPNC, especially when the uplink channel conditions are asymmetric. The results in Nakagami-m channels also imply that COPNC will provide higher BER gain with more severe fading depth. Potential works about COPNC are also presented in this paper.