Physical Layer Security Performance Analysis for Relay-Aided Visible Light Communication System

The risk of information leakage increases when the relay technology is introduced to extend the communication range and improve the quality of communication services of cell-edge users in visible light communication (VLC) systems. To evaluate these security risks, physical layer security (PLS) performance for decode-and-forward (DF) relay-aided VLC system is investigated in this paper. Specifically, the theoretical expressions of the upper and lower bounds of the security outage probability (SOP) for the DF relay-aided VLC system under the amplitude constraint are obtained based on a stochastic geometry analysis method. Monte Carlo simulation validates the correctness of the derived theoretical expressions of the upper and lower bounds of the SOP. Moreover, simulation results show that the security outage performance of the DF relay-aided VLC system is deteriorated compared with the non-relay VLC system. Furthermore, the influences of the eavesdroppers' distribution density, the radiation radius of LED source, the radiation radius and deployment height of the relay on the SOP have been investigated. Last but not least, the optimal deployment height of the relay can be determined for achieving the optimum security outage performance. These parameters can effectively guide the design of the secure relay-aided VLC system.