Joint Transceiver Optimization for Multiuser Multi-Antenna Relay Systems With Energy Harvesting

In this paper, a multiuser multi-antenna relay system with wireless power transfer is investigated, where the relay node harvests energy from the radio frequency signal sent from the source node and utilizes the harvested energy to forward the information signal to users. Under the transmit power constraints at all nodes, the optimization problem is formulated which maximizes the achievable sum rate of the relay system by optimizing the time switching (TS) factor and the source and the relay precoding matrixes. We divide the complex non-convex objective problem into several subproblems which are solved by the proposed alternating optimization (AO) scheme. We also propose a novel power allocation scheme across subchannels to maximize the sum rate. Since the objective function to optimize the relay power allocation is not convex, difference of convex programming is adopted to transform the original non-convex problems into convex optimization problems. Simulation results are provided to verify the analysis and demonstrate the efficiency of the proposed AO scheme.