# Secure Satellite Communications via Multiple Aerial RISs: Joint Optimization of Reflection, Association, and Deployment

## TL;DR

This paper proposes a joint optimization framework for secure satellite communications using aerial reconfigurable intelligent surfaces, enhancing security and performance through optimized reflection, association, and deployment strategies.

## Contribution

It introduces a novel joint optimization approach for ARIS-assisted satellite systems, addressing the complex problem of secure multi-beam multicast communication.

## Key findings

- Significant improvement in secure communication performance.
- Effective joint optimization of reflection, association, and deployment.
- Insights into ARIS deployment for future satellite networks.

## Abstract

Satellite communication is envisioned as a key enabler of future 6G networks, yet its wide coverage with high link attenuation poses significant challenges for physical layer security. In this paper, we investigate secure multi-beam, multi-group satellite communications assisted by aerial reconfigurable intelligent surfaces (ARISs). To maximize the sum of achievable multicast rates among the groups while constraining wiretap rates, we formulate a joint optimization problem involving transmission and reflection beamforming, ARIS-group association, and ARIS deployment. Due to the mixed-integral and non-convex nature of the formulated problem, we propose to decompose the problem and employ the block coordinate descent framework that iteratively solves the subproblems. Simulation results demonstrate that the proposed ARIS-assisted multi-beam satellite system provides a notable improvement in secure communication performance under various network scenarios, offering useful insights into the deployment and optimization of intelligent surfaces in future secure satellite networks.