Distributionally Robust Physical-Layer Security for Satellite Communication via Aerial Reconfigurable Intelligent Surface

2026-05-29

AI Summary

This work addresses the physical-layer security challenges in satellite communications arising from broadcast transmission, long-distance propagation, and highly dynamic channels. To enhance secrecy performance, the paper proposes a space-based auxiliary reconfigurable intelligent surface (ARIS)-assisted multi-beam secure transmission scheme. By jointly optimizing transmit and reflective beamforming, and modeling channel distribution uncertainty via moment-based ambiguity sets, the authors reformulate probabilistic secrecy constraints into a deterministic form using conditional value-at-risk (CVaR). This yields a distributionally robust secrecy rate maximization model, which is efficiently solved via an alternating optimization algorithm. Numerical results demonstrate that the proposed approach significantly improves system secrecy performance and maintains stable, reliable secrecy rates across various channel error distributions.

Abstract

Satellite communications are envisioned as a key enabler for ubiquitous coverage in future 6G networks, yet the broadcast nature renders them vulnerable to eavesdropping, especially given the long-distance transmissions and associated high uncertainties. In this paper, we propose the physical layer security enhancement for multi-beam satellite communications with the assistance of an aerial reconfigurable intelligent surface (ARIS). Considering the high dynamics and uncertainties of channels, we characterize the channel distribution with moment-based ambiguity sets. Accordingly, a distributionally robust secrecy rate optimization is formulated through joint design of transmit and reflection beamforming. We then introduce a conditional value-at-risk-based reformulation to convert the probabilistic constraints into deterministic forms. An alternating optimization framework is subsequently employed to iteratively update the transmit and reflective beamforming vectors until convergence. Simulation results demonstrate that the proposed distributionally robust scheme significantly enhances secrecy performance, and maintains reliable performance across various channel error distributions.

Problem

• satellite communication
• physical-layer security
• eavesdropping
• channel uncertainty
• secrecy rate

Innovation

• Distributionally Robust Optimization
• Reconfigurable Intelligent Surface
• Physical-Layer Security
• Satellite Communication
• Conditional Value-at-Risk