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.