Linear transceivers for full duplex MIMO relays

Full duplex (FD) relays can provide throughput enhancements compared to half duplex (HD) operation. However, FD relays are known to suffer from loopback interference (LI) issues that degrade their performance. In this paper, we present several different precoder and weight vector designs using the principles of signal to leakage plus noise ratio, minimum mean square error and zero forcing to investigate the performance of a FD multiple input multiple output (MIMO) relay system. We derive a closed-form solution for the covariance matrix of the transmitted signal at the relay which enables a performance evaluation of a wide range of transceivers. Results show that performance improvements over HD can be achieved using only spatial processing (linear precoders and receive combiners) and that LI reduction at the relay is preferable to pre-cancellation at the relay transmitter.