Movable Antenna-Aided Secure LEO Satellite Networks: Joint Antenna Position and Beamforming Optimization

2026-05-18

AI Summary

This work addresses the severe physical-layer security threat in 6G low Earth orbit (LEO) satellite communications, where the broadcast nature and dense deployment lead to minimal angular separation between legitimate users and eavesdroppers. To tackle the time-varying satellite channel, the paper introduces, for the first time, a movable antenna technique and proposes a joint optimization framework that simultaneously designs ground station transmit beamforming and antenna placement to maximize the average secrecy rate. An alternating optimization approach is employed, combining semidefinite relaxation for the beamforming subproblem with both a high-precision successive convex approximation and a low-complexity differential evolution algorithm for antenna position optimization. Simulation results demonstrate that the proposed scheme significantly outperforms conventional fixed-antenna strategies in scenarios with small angular separation, thereby substantially enhancing secrecy performance.

Abstract

The broadcast characteristics of sixth-generation (6G) low-earth orbit (LEO) satellite communications raise serious security issues. Movable antenna (MA) technology offers a promising physical layer security (PLS) solution by flexibly reconfiguring antenna positions to exploit additional spatial degrees of freedom. However, in highly dense LEO satellite constellations, the legitimate satellite and potential eavesdropping satellites may exhibit small angular separations, which poses significant challenges for the design of secure transmission schemes. To address this challenge, this paper proposes an MA-assisted secure transmission scheme for time-varying LEO satellite communications, where a ground station equipped with an MA array communicates with a serving satellite, while the other visible satellites are regarded as potential eavesdroppers. We maximize the average secrecy rate by jointly optimizing the transmit beamforming and MA positions. An alternating optimization (AO) framework is developed, where semidefinite relaxation is adopted for the beamforming optimization subproblem, while high-accuracy successive convex approximation (SCA) and low-complexity differential evolution (DE) algorithms are proposed for the MA position optimization subproblem. Numerical results demonstrate that the proposed MA-assisted LEO secure transmission scheme consistently achieves superior performance compared to the conventional fixed-position antenna scheme.

Problem

• LEO satellite networks
• physical layer security
• movable antenna
• angular separation
• secure transmission

Innovation

• Movable Antenna
• Physical Layer Security
• LEO Satellite Networks
• Joint Optimization
• Secrecy Rate