PLS of Relay-Aided VLC With RIS-Assisted Eavesdropper

In this paper, the physical layer security (PLS) in visible light communication (VLC) is investigated where the eavesdropper (ED) is assisted with the reconfigurable intelligent surface (RIS). Here, in the relay-aided system model, the ED is equipped with a new RIS type. The model also accounts for the received signal-dependent noise. For various trusted relaying schemes such as decode-and-forward (DF), amplify-and-forward (AF), and cooperative jamming (CJ), closed-form expressions of the lower and upper bounds on secrecy rate regions are derived under power constraints. Moreover, the effect of channel state information (CSI) uncertainty is analysed, as a practical condition. Considering this effect, it is demonstrated that the CJ scheme resists eavesdropping by increasing the noise and interference on the illegitimate user. The simulation results show that applying the RIS technique does not increase the signal-to-noise ratio of the ED in the CJ scheme in comparison with DF and AF schemes.