Optimal RIS Allocations for PLS with Uncertain Jammer and Eavesdropper

With deployment of 5G and emerging 6G networks, the demand of wireless communication for transmission capacity as well as the transmission security in consumer electronics is increasing. Reconfigurable intelligent surface (RIS) has shown a great potential in physical layer security (PLS) due to its enabling technology to engineer the radio signal prorogation. In this paper, we study PLS problems of RIS-assisted wireless communication system, where the RIS is deployed to aid pair of the transmitter (Alice) and receiver (Bob) under the active jamming (Jammer) and eavesdropper (Eve) attack. Different from traditional RIS schemes, our proposed scheme divides the RIS into two parts which not only enhances the legitimate user performance but also suppresses the eavesdropper. Specifically, the location of the jammer is also considered with two different scenarios, i.e., the distance between the jammer and RIS is smaller/greater than that of the one between the transmitter and RIS. Considering the influence of RIS reflection coefficient, path loss and uncertain jammer locations, we analyze the system performance based on the legitimate and eavesdropping channels, providing the upper and lower bounds of achievable received signal-to-noise ratio (SNR) instead of the secrecy outage probability (SOP). In addition, the simulation and asymptotic results reveal the location influence of the interference on the secrecy performance and the superiority of the proposed scheme.