This paper considers the physical layer security (PLS) of a simultaneous wireless information and power transfer (SWIPT) relay communication system composed of a legitimate source–destination pair and some eavesdroppers. Supposing a disturbance of channel status information (CSI) between relay and eavesdroppers in a bounded ellipse, we intend to design a robust beamformer to maximum security rate in the worst case on the constraints of relay energy consumption. To handle this non-convex optimization problem, we introduce a slack variable to transform the original problem into two sub-problems firstly, then an algorithm employing a semidefinite relaxation (SDR) technique and S-procedure is proposed to tackle above two sub-problems. Although our study was conducted in the scene of a direct link among source, destination, and eavesdroppers that is non-existing, we demonstrate that our conclusions can be easily extended to the scene for which a direct link among source, destination and eavesdroppers exist. Numerical simulation results compared with the benchmark scheme are provided to prove the effectiveness and superior performance of our algorithm.
We deeply explore the physical layer security of simultaneous wireless information and power transfer (SWIPT) network which uses the cooperative non-orthogonal multiple access (NOMA) technique in this paper. A novel cooperative NOMA strategy in which the near user with full-duplex ability is employed as a friendly relay by using SWIPT technology to harvest energy is proposed to enhance the capability of user far from base station (BS). Moreover, artificial-noise (AN) cooperation scheme is also proposed to improve the physical layer security while minimizing the base station transmitting power. To tackle nonconvex problem related to above cooperative NOMA strategy, we present a semidefinite-relaxation (SDR) and successive convex approximation (SCA) scheme. Numerical simulation results show that compared with other schemes, our scheme can significantly reduce the transmit power required by BS and improve the physical layer security of network.
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