Symbol-Based Physical-Layer Network Coding for Two-Way Relay Channel

A symbol-based physical layer network coding (PNC) scheme is proposed for the two-way relay channel where the relay node is equipped with multiple antennas. Unlike the traditional binary PNC that focuses mainly on BPSK modulation, the proposed symbol-based PNC is tailored for the general MPSK modulation. In particular, the product of the two modulated signals is considered as a network-coded symbol, which exploit the characteristic of MPSK modulation to compact the solution space of the intended network-coded symbol. Based on the autocorrelation of the received signal at the relay node, a novel PNC-oriented detection scheme is developed to estimate the network-coded symbol for broadcasting. The proposed scheme achieves receive diversity advantage with linear complexity at the relay node. In addition, the proposed scheme can effectively handle information exchanging with asymmetric data rates between the two sources. Simulation results show that the proposed scheme outperforms other linear-MIMO detection based counterparts in terms of diversity order, and it also outperforms the existing decode-and-forward (DF) and amplify-and-forward (AF) approaches when dealing with the asymmetric information exchanging.