Artificial Noise Aided Precoding with Imperfect CSI in Full-Duplex Relaying Secure Communications

In Rayleigh fading channels, to enhance the secrecy performance of wireless communication systems and efficiently disturb the interception of eavesdroppers, the multiple-antenna source node utilizes the artificial noise aided precoding (ANP) strategy with imperfect channel state information to emit the confidential information and the artificial noise simultaneously. Besides, the two-antenna decode-and-forward relay node applies the full-duplex (FD) relaying protocol, and the destination node which contains multiple antennas adopts the maximum ratio combining technique. Taking into account the existence of self-interference at the relay, the closed-form expression of approximate ergodic achievable secrecy rate (EASR) for any value of antenna number and that of exact EASR in the case of large-scale antenna array are derived, respectively. To extract more distinct insights from the considered system and hence obtain some simple and meaningful conclusions, the asymptotic performance analyses in two different asymptotic cases are studied. The numerical simulations validate the correctness of our theoretical derivation and analysis, which indicates that the ANP scheme combined with the FD relaying can achieve considerable secrecy performance.