Joint Robust Design for Secure AF Relay Networks With SWIPT

In this paper, we investigate the physical layer security for amplify-and-forward relay networks with simultaneous wireless information and power transfer. Specifically, by considering the dual-functional desired receiver, which is capable of decoding information and energy harvesting (EH), and assuming that only imperfect eavesdroppers' channel state information can be attained, we propose a joint robust cooperative beamforming, artificial noise, and power splitting scheme. We formulate the relay power minimization problem under both the secrecy rate constraint and the EH constraint, which is non-convex and hard to tackle. To tackle this problem, we propose a two-level optimization approach, which involves 1-D search and the semi-definite relaxation. In addition, we testify that the SDR can obtain the rank-one optimal solution. Simulation results show that the proposed robust scheme achieves better secrecy performance than other schemes.