Two-Way Full-Duplex Massive Mimo Relaying With Correlated Multi-Antenna User Pairs

This paper considers a multi-pair two-way full-duplex relaying system with multiple-input-multiple-output (MIMO) users. Each pair of users exchange information with the aid of a massive MIMO decode-and-forward (DF) relay. Low-complexity processing at the relay based on maximum ratio combining/maximum ratio transmission (MRC/MRT) is presented, and the system is evaluated in terms of the achievable sum-spectral efficiency. The direct link between all user nodes is considered non-negligible, which is suitable for urban environments, however, we assume that the users are unaware of the direct link and so is treated as interference. Moreover, we consider correlated antenna arrays at the relay and user nodes and the detrimental effect of spatial correlation is investigated.