On full message exchange in MIMO DF multi-way relay networks

This paper considers a half-duplex multi-way relay (MWR) network where K users exchange messages among themselves with the assist of a relay. The relay is equipped with N antennas and all the users are each equipped with M antennas. The rate region of the network is first characterized by the cut-set bound, and then the degree-of-freedom (DoF) is computed. It is shown that the maximum DoF of the MWR network is K min{M,N} /2(K-1), and a DoF of equation can be achieved by the decode-and-forward (DF) relaying strategy. Using the technology of zero-forcing signal alignment and successive interference cancellation, a DF scheme is further proposed to provide a practical and efficient mechanism for the K-user MWR (K ≥ 2). Compared to the existing schemes, the new scheme has the advantage either in interference cancellation or in delay. Simulations confirm the effectiveness of the new scheme.