Physical Layer Security in RIS-Assisted THz-Enabled LEO Satellite Communications

Abstract

Satellite networks are expected to play a key role in achieving global coverage in the sixth generation (6G) of wireless communications systems. Despite their potential, the operation of extensive satellite constellations introduces distinct challenges, especially in ensuring robust physical-layer security. To address these concerns, emerging strategies involve the deployment of reconfigurable intelligent surfaces (RISs) and the utilization of high-frequency bands like the terahertz (THz) spectrum, both of which offer significant potential for improving the security and efficiency of satellite-based communication systems. This paper examines the secrecy performance of a satellite communication system enhanced by an RIS and operating in the THz band. The system comprises a legitimate link between two satellites, aided by an RIS, and an eavesdropper employing a reflective device to intercept the communication. We provide analytical closed-form approximations for key metrics, including the secrecy outage probability (SOP), the average secrecy rate, the intercept probability, and the probability of non-zero secrecy capacity. Additionally, an asymptotic analysis of the SOP at high signal-to-noise ratios is conducted, providing valuable insights into the system’s behavior. Our results underscore the promise of RIS and THz technologies for achieving robust and secure satellite communications in 6G.