Simultaneous Wireless Information and Power Transfer in a MISO Broadcast Channel with Confidential Messages

In this paper, we propose a secure transmission scheme for simultaneous wireless information and power transfer (SWIPT) in a multiple-input single-output (MISO) broadcast channel with confidential messages, where each receiver utilizes the power splitting approach to decode information and harvest energy simultaneously, and it also acts as a potential eavesdropper for the independent message sent to the others. By jointly optimizing the transmit beamforming vectors, covariance of artificial noise, and receive power splitting (PS) ratios for all receivers, we aim to maximize the total harvested energy while guaranteeing the secrecy rate constraint at each receiver and the total transmit power constraint at the transmitter, which is a non-convex optimization and hard to solve. In this paper, we propose a two-stage optimization approach based iterative algorithm to tackle such a challenging problem. Moreover, we prove that the proposed algorithm can achieve convergence, and also analyze its computational complexity. Finally, simulation results are provided to demonstrate the performance of our proposed algorithm.