Transmission strategies for wireless powered MIMO relay systems

This paper studies a multiple input multiple output (MIMO) simultaneous wireless information and power transfer (SWIPT) relay system, in which the source node (SN) send information and energy simultaneously to the relay node (RN), and the RN forward the received signal to the destination node (DN) powered by harvested energy. In particular, we consider two SWIPT receiver designs, namely power splitting (PS) and antenna switching (AS) in the relay system. For each design, iterative algorithms based on convex optimization technique are proposed to maximize the system rate. Furthermore, in order to strike a balance between computational complexity and system performance, based on the AS scheme, we propose a low complexity optimization method for PS scheme where a suboptimal PS ratio is given. Numerical results are provided to evaluate the performance of the proposed algorithm for MIMO SWIPT relay systems. It is shown that the performance of the proposed suboptimal method approaches that of the optimal PS scheme.