Physical Layer Security for RIS-Assisted Dual-Hop PLC/RF Communication Systems

In this paper, we discuss the physical layer security of reconfigurable intelligent surface (RIS) assisted power line communication (PLC)/radio frequency (RF) communication system. The source S communicates with the destination D with the help of a decode-and-forward relay and an RIS. Specifically, the S transmits the signal to R through PLC link, and the R decode and forwards the received signal to the RIS by RF link. Then, the RIS reflects the received signal to D. An eavesdropper attempts to eavesdrop information from the relay R's broadcast signal. It is assumed that the PLC channel follows log-normal fading, while the RF link undergoes Rayleigh fading. To evaluate the system security performance, the closed-form expressions for the secrecy outage probability, the ergodic secrecy capacity and the effective secrecy throughput are derived. Numerical simulations results show that reducing the arrival probability of impulse noise, increasing the number of reflective elements, and increasing the transmit signal-to-noise ratio can effectively improve the safety performance of the system.