Joint relay beamforming and receiver processing for multi-way multi-antenna relaying

We consider a multi-way relay network with multiple users exchanging information with each other via a multi-antenna relay. We jointly design relay beamforming matrices and users' linear processing receivers to maximize the minimum signal-to-interference-and-noise ratio (SINR) under the relay power budget. We solve the joint optimization problem by iteratively optimizing the relay beam matrices and receiver processing matrices. For the latter, both maximum-ratio-combining (MRC) receiver and zero-forcing (ZF) receiver are designed. We show that the MRC receiver leads to the optimal solution of the original joint optimization problem, while the ZF receiver has lower complexity for computation. Simulation shows that our proposed algorithm for joint design yields higher achievable sum rate than the existing partial ZF (PZF) method which uses sum rate maximization as the design objective.