Transmit power optimization for multiantenna decode-and-forward relays with loopback self-interference from full-duplex operation

We develop transmit power control schemes for a regenerative full-duplex relay link. The focus is on MIMO scenarios with multiple antennas at all communicating nodes. As a new aspect for the optimization problem, we note that practical full-duplex relays are subject to unavoidable self-interference propagating from the transmit antenna array to the receive antenna array. Thus, residual interference remaining after mitigation needs to be explicitly modelled. Multiantenna techniques facilitate performance improvement by directing the interference to the least harmful spatial dimensions. As a result of transmit power optimization, the end-to-end transmission rate is maximized while, at the same time, the relay transmit power may be decreased. Finally, we compare full-duplex relaying to half-duplex relaying, i.e., we illustrate the benefit of choosing one over the other and the conditions where each one is preferred.