Robust two-way amplify-and-forward MIMO relay beamforming with non-reciprocal and reciprocal CSI

In this paper, we investigate robust beamforming design for two-way amplify-and-forward (AF) MIMO relaying system with Gaussian distributed channel errors. Take mean-square-error (MSE) of the detected data as the design criteria, beamforming matrix at relay is optimized under imperfect channel state information (CSI). Both frequency-division-duplex (FDD) system and time-division-duplex (TDD) system are considered. Then two algorithms are proposed based on a framework of quadratic programming. The effectiveness of the proposed robust design for different channel mode are finally demonstrated by the simulation results.