Simplified Relay Algorithm for Two-Way MIMO Relay Communications

In this paper, we investigate the challenging problem of joint source and relay optimization for two-way linear non-regenerative multiple-input multiple-output (MIMO) relay communication systems. First, a novel relay amplifying matrix is proposed which significantly reduces the computational complexity of the optimal relay design with only a marginal performance degradation. Interestingly, we show that the proposed relay matrix is indeed optimal for some special cases. Second, a semidefinite programming (SDP)-based source matrices optimization algorithm is developed. Then the source and relay optimization algorithms are carried out iteratively to minimized the sum mean squared error of the signal waveform estimation in a two-way MIMO relay system. The performance of the proposed algorithm is demonstrated by numerical simulations