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

TL;DR

This paper introduces a movable antenna-based secure transmission scheme for LEO satellite networks, jointly optimizing antenna positions and beamforming to enhance security against eavesdroppers.

Contribution

It proposes a novel joint optimization framework using alternating optimization, semidefinite relaxation, SCA, and DE algorithms for secure LEO satellite communications.

Findings

The scheme outperforms fixed-antenna schemes in secrecy rate.

Joint optimization significantly improves security performance.

Numerical results validate the effectiveness of the proposed approach.

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.