Robust AN-aided Secure Beamforming for Full-Duplex Relay System with Multiple Eavesdroppers

In this paper, we investigate the physical layer security of a full-duplex decode-and-forward relay-aided system in the worst case, where all channel state informations are realistic imperfect. For the sake of confidentiality of signals transmitted from source to destination, a robust artificial noise (AN)-aided beamforming scheme is proposed. Explicitly, our objective function is that of maximizing the worst-case secrecy rate under the transmit power constraints, by jointly optimizing the beamforming matrix and AN at the source and the relay. To overcome the non-convexity of the robust AN-aided secure beamforming problem, we transform it into multi-block convex problems, where the semi-infinite linear matrix inequality is applied to eliminate the channel uncertainties. As a benefit, our proposed robust AN-aided secure beamforming scheme obtains substantial secrecy performance gains, which verifies the efficiency of the proposed scheme.