Physical-Layer Security for Indoor Hybrid PLC/VLC Networks With NOMA

Hybrid power line communication (PLC)/visible light communication (VLC) networks have been demonstrated to be crucial for indoor practical communications and have attracted widespread attention. However, most current research in hybrid PLC/VLC networks focus mainly on communication reliability and resource allocation, and little has been carried on physical layer security. In this paper, we investigate the secure communication of a hybrid PLC/VLC network with two non-orthogonal multiple access legitimate users. During the two-hop PLC and VLC transmission, two eavesdroppers attempt to wiretap the confidential information from the PLC link via power line, and from the VLC link via visible light, respectively. Based on the randomness of the impulsive noise arriving at the PLC link, and the randomness of users' positions covered by the VLC link, the channel statistical characteristics of the PLC and VLC links are derived, respectively. Furthermore, the approximate closed-form expressions of secrecy outage probability (SOP) are determined. Simulations are performed to validate the effectiveness of theoretical results, and simulation results show that to get a high-level secrecy outage performance, the parameters of both the PLC and VLC links should be jointly designed. Furthermore, with regard to SOP, it is the worst case for both the PLC and VLC links eavesdropping, as compared to only PLC link eavesdropping or only VLC link eavesdropping.