Differential space-time network coding in MIMO two-way relay channel network

This paper focuses on noncoherent detection scheme for multiple-input multiple-output two-way relay channel network with two two-antennas source nodes and one single-antenna relay node. An orthogonal differential space-time network coding (ODSTNC) scheme based on relay detection and forward protocol is proposed. The proposed scheme combines space-time coding with network coding, and the differential modulation and detection are used in both multiple access stage and broadcast stage. The multiplesymbol differential detection is employed at the relay. The maximum likelihood decision and its low-complexity sphere decoding decision are given. The upper and lower bounds on the average symbol error probability for this system under differential binary phase shift keying (DBPSK) are derived, and a diversity order of 2 is confirmed to be achieved. The simulation results show that the ODSTNC scheme has good performance, and it is available for the applications of far distance signal transmission between two terminals where channel state information is unknown. Copyright (c) 2014 John Wiley & Sons, Ltd.