Precoding for multiuser MIMO full-duplex amplify-and-forward relay uplink communication systems

This paper examines the precoding matrix design for a multiuser multiple-input multiple-output full-duplex (FD) relay uplink communication system with an amplify-and-forward relay. The main problem in FD systems is the loop interference (LI) cancellation, and perfect LI cancellation is not possible so residual LI exists. Linear precoders are used at the sources and relay, and a minimum mean-squared-error receiver is employed at the destination to reduce the influence of the residual LI. An iterative method is developed to solve the highly nonconvex joint source, relay, and receiver optimization problem. Simulation results are presented which show that the proposed iterative optimization algorithm provides better performance than existing half duplex systems in terms of the achievable rate even with residual LI.