Efficient Full-Duplex Relaying With Joint Antenna-Relay Selection and Self-Interference Suppression

In this paper, we propose a joint relay and transmit/ receive (Tx/Rx) antenna mode selection scheme (RAMS) in the general full-duplex (FD) relay networks consisting of one source, one destination, and N FD amplify-and-forward (AF) relays. Each FD relay is equipped with two antennas, one for receiving and the other for transmitting. In the proposed scheme, each antenna of the FD relay is able to transmit/receive the signal. Each relay adaptively selects its Tx antenna and Rx antenna based on the instantaneous channel conditions, and the optimal single relay with the optimal Tx/Rx antenna configuration is selected to maximize the end-to-end signal to interference and noise ratio (SINR) of the FD relay system. The performance of the proposed scheme is analyzed. The closed-form expressions of the outage probability, average symbol error rate, and the ergodic capacity are derived. The analytical results are verified by the simulations. To reduce the error floor and capacity ceiling caused by the self-loop interference in FD relay, we propose a RAMS scheme with adaptive power allocation (RAMS-PA). We provide an upper bound and a lower bound of the end-to-end SINR for RAMS-PA scheme, and prove that the error floor can be removed in the RAMS-PA scheme. Results show that the proposed scheme achieves an extra spatial diversity in the medium SNR region due to the FD antenna selection at the relay nodes and considerably improve the system performance compared to the conventional FD relay selection scheme with fixed relay Tx and Rx antennas.