Signal detection and joint constellation modulation for two-way relaying with multiple antennas

In this paper, a MMSE based signal detector with interference cancellation (MMSE-IC) is proposed for a two-way relay channel using the decode-and-forward strategy, including two single-antenna source nodes and a multiple-antenna relay node. It is demonstrated that by using the proposed MMSE-IC detector, the BER at the relay when extracting the information of the two source nodes in the multiple-access (MA) phase, is similar to that of the optimal maximum likelihood detection, while retains a low structural and computational complexity. At the same time, asymmetric transmission scenarios where the two sources use different modulation schemes are also investigated. Simulation results show that a more efficient relay scheme and further performance improvements can be achieved by joint designing the constellation mapping of the network-coded signal at the multiple-antenna relay for the broadcast channel (BC) phase transmission.