Secure Beamforming for Simultaneous Wireless Information and Power Transfer in Wireless-Powered Full-Duplex Relay Networks

In this paper, we study secure beamforming for simultaneous wireless information and power transfer (SWIPT) in wireless-powered full-duplex (FD) relay networks. The relay assists transmission of confidential information, while simultaneously harvesting the energy with power switching scheme by the radio-frequency (RF) signals. We propose a joint amplify-and-forward beamforming (AB) and energy signal (AB-ES) with the receiver power splitting strategy (PS) scheme to maximize the secrecy rate under harvesting energy constraints. Since these constraints make the optimization problems become non-convex and hard to tackle. We propose a two-level optimization problem to solve this problem. The out part can be solved via the one-Dimensional search, and the inner part can be solved by semidefinite relaxation (SDR) technique. Simulation results show that the proposed scheme outperforms other schemes.