Widely Linear Signal Processing for Two-Way Relaying with MIMO Amplify and Forward Relays

In this paper, we develop widely linear transmit strategies for two-way relaying networks with single or multiple pairs of users and a MIMO amplify and forward relay. By taking advantage of the noncircularity of the complex-valued transmitted signals, a significant performance gain is obtained over linear transmit strategies when SNR balancing or relay transmit power minimization is chosen as the system design criterion and there are multiple pairs of users. We also propose a widely linear dual channel matching scheme and perform a large scale analysis over it. This theoretical analysis shows that the gain can drop to 20 % when compared to a linear design.