Residual Energy Optimization for MIMO SWIPT Two-Way Relaying System

In this paper, we investigate the multiple-input- multiple-output (MIMO) two-way amplify-and-forward (AF) relaying system with simultaneous wireless information and power transfer (SWIPT), where two users harvest energy from the relay signal by power splitting (PS) scheme. Under the transmit power constraints at all nodes, the energy optimization problem is formulated which maximizes the total residual energy of two users by optimizing the splitting ratios and the precoding matrixes at the relay and two users, while still guaranteeing sufficient signal-to-noise ratios (SNR) at two user nodes. We divide the complex non-convex objective problem into three subproblems which are then solved through the proposed alternating optimization (AO) scheme. Numerical results are provided to verify the analysis and demonstrate the efficiency of the proposed scheme.