Low-complexity two-way AF MIMO relay strategy for wireless relay networks

In this paper, a two-way amplify-and-forward (AF) wireless relay network consisting of two sources with multiple M antennas and one relay with multiple N antennas is investigated with a self-interference cancelation process. The relay amplifying matrix that has the low computational complexity is optimized under the relay transmit power constraint based on zero-forcing (ZF) criterion with a singular value decomposition (SVD) method. The sum rate behavior is analytically and numerically studied by adopting the derived optimal relay amplifying matrix. Additionally, the system performance is evaluated in relation to the system bit error rate (BER) and sum rate by computer simulation. Numerical results show that the eigen beamforming is more competitive than the equal-gain beamforming for the two-way relaying systems.