Optimal Transceiver Designs for Wireless-Powered Full-Duplex Two-Way Relay Networks With SWIPT

This paper studies simultaneous wireless information and power transfer in full-duplex (FD) two-way relay networks, where two energy-constrained sources are served by a FD multi-antenna power-supply relay. Using FD technique at the relay can cause self-interference (SI) for the signal forwarding, but this SI can be useful for energy harvesting at two sources. To reasonably compress and utilize the SI, we consider a utility optimization problem aiming to maximize the total harvested energy by jointly optimizing the transmit power, the power splitting ratio at the sources and the beamforming matrix at the relay. In specific, we consider two relaying protocols, amplify-and-forward and decode-and-forward. To solve the complex non-convex problem, we decouple the objective problem into two subproblems which can be solved by the proposed semidefinite relaxation technique and the derived constraints activation solution. We show that the optimal solution of certain subproblems can be obtained in the closed-form. By this way, the objective problem can be finally tackled by utilizing a convergence guaranteed alternating optimization algorithm. Numerical results show that the proposed FD scheme achieves significant improvement of the energy harvesting efficiency compared with the existing works with different transmission protocols, i.e., half-duplex, perfect FD, and non-joint FD.