FAS for Secure and Covert Communications

TL;DR

This paper introduces a fluid antenna system (FAS) that enhances secure and covert communications by optimizing antenna positions and beamforming, outperforming fixed-position antennas in secrecy and covertness.

Contribution

It proposes an alternating optimization algorithm combining penalty-based and majorization-minimization methods for joint optimization of FAS parameters.

Findings

FAS significantly improves secrecy rate and covertness.

The proposed algorithm effectively optimizes fluid antenna positions and beamforming.

Simulation results demonstrate superior performance over fixed-position antenna schemes.

Abstract

This letter considers a fluid antenna system (FAS)-aided secure and covert communication system, where the transmitter adjusts multiple fluid antennas' positions to achieve secure and covert transmission under the threat of an eavesdropper and the detection of a warden. This letter aims to maximize the secrecy rate while satisfying the covertness constraint. Unfortunately, the optimization problem is non-convex due to the coupled variables. To tackle this, we propose an alternating optimization (AO) algorithm to alternatively optimize the optimization variables in an iterative manner. In particular, we use a penalty-based method and the majorization-minimization (MM) algorithm to optimize the transmit beamforming and fluid antennas' positions, respectively. Simulation results show that FAS can significantly improve the performance of secrecy and covertness compared to the fixed-position antenna (FPA)-based schemes.