Hybrid Beamforming Full-Duplex Relay in Massive MIMO Systems

In this paper, we consider a point-to-point MIMO system with the amplified-and-forward full-duplex relay that the source can communicate with destination through the relay. The optimization problem for this scenario is non-convex, and finding the hybrid beamforming matrices, is a significant challenge. Here we propose two methods to design hybrid beamforming matrices in a full-duplex relay scenario. In the first method, we separate the transmitter and receiver sides of the relay and formulate the optimization problems. In the second method, we designed the beamforming relay matrices in a joint manner and proposed an algorithm to find a nearly-optimum full-duplex relay to achieve higher performance. Simulation results show that the joint optimization method achieves higher spectral efficiency than the separation method (first method). In addition the impact of the number of RF chains, is carried out by simulation. The simulation demonstrates that the number of antennas in the relay has an optimum value for a fixed number of RF chains.