Two-way MIMO relay beamforming scheme for sum-rate maximization approach based on second-order statistics

In this paper, sum-rate maximization is investigated in a two-way MIMO relay network where a multi-antenna relay node assists two transceivers for exchanging their data. For sum-rate maximization, beamforming weights are designed whereas total transmit power constraint in the multi-antenna relay node is satisfied. Assuming that the second order statistics (SOS) of channel state information (CSI) are only available, we confront with a non-convex optimization problem. Using the semidefinite relaxation (SDR) technique and by help of the bisection search method, the beamforming weights are specified. Simulation results show, in a constant maximum allowable relay total transmit power, increasing the number of antennas of multi-antenna relay node increases the maximum sum-rate.