Secure Transmission with a Full-Duplex Relay in Power Line Communications

With the increasingly prominent security problems of Industrial Internet and the rapid development of computing technology, the security of power line communication (PLC) based on classical encryption technology faces new challenges. In this paper, a secure transmission scheme of PLC relay network based on full-duplex (FD) is proposed. In this scheme, the transmitter transmits the composite signal containing the information-bearing signal and the jamming signal. The relay forwards the received signal in the last time slot according to the amplify-and-forward (AF) strategy while receiving the signal transmitted by the transmitter. The receiver transmits the jamming signal while receiving the signal transmitted by the relay. Based on the lognormal correlated channel model and the Bernoulli-Gaussian noise model, we derive the closed-form expressions for average secrecy capacity (ASC), secrecy outage probability (SOP), and effective secrecy throughput (EST), assuming maximum ratio combining are utilized at the eavesdropper. According to the theoretical analysis, we find the optimal power allocation to improve the secrecy performance with the external eavesdropper or the untrusted relay. Furthermore, Monte-Carlo simulation is utilized to verify our analysis. Simulation results show that the proposed method is superior to the traditional scheme.