  In this paper, we propose a full-duplex relay (FDR) based on a zero-forcing
beamforming (ZFBF) for a multiuser MIMO relay system. The ZFBF is employed at
the base station to suppress both the self-interference of the relay and the
multiuser interference at the same time. Numerical results show that the
proposed FDR can enhance the sum rate performance as compared to the
half-duplex relay (HDR), if sufficient isolation between the transmit and
receive antennas is ensured at the relay.
