Polar-coded Gaussian Multiple-Access Channels with Physical-Layer Network Coding

In this paper, we propose a two-user polar-coded physical-layer network coding (TU-PC-PNC) scheme for the Gaussian multiple access channel (GMAC) to enhance the transmission reliability. We first investigate the characteristics of polar encoding and derive the concatenated codeword structure, by which we can implement the message exclusive OR (XOR)-based PNC via code construction and improve the channel polarization effect. The PNC-aided decoding rule based on the concatenated codeword is then invented to compute the initial messages for recovery. In addition, we introduce the joint optimization framework by Monte Carlo-based method, which can be used to optimize the polar code and power allocation with maximized sum user rate. The capacity analysis of the bit-channels and simulation results show that the proposed TU-PC-PNC can significantly outperform the benchmark scheme by more than 1 dB under the GMAC