Physical Layer Security Enhancement Exploiting Intelligent Reflecting Surface

TL;DR

This paper explores how intelligent reflecting surfaces can be used to improve physical layer security in wireless communications by jointly optimizing beamforming strategies, achieving near-optimal performance efficiently.

Contribution

It introduces a novel joint optimization algorithm for active and passive beamforming in IRS-assisted secure communications, combining fractional programming and manifold optimization.

Findings

The proposed algorithm nearly reaches the performance upper bound.

It demonstrates fast convergence in simulation.

Enhances physical layer security effectively.

Abstract

In this letter, the use of intelligent reflecting surface (IRS) to enhance the physical layer security of downlink wireless communication is investigated. Assuming a single-antenna legitimate user and a multi-antenna eavesdropper, we propose an effective algorithm to jointly optimize the active and passive beamforming. In the proposed algorithm, the optimal transmit beamforming vector at the BS under fixed IRS phase shifts is derived, and a low-complexity algorithm based on fractional programming (FP) and manifold optimization (MO) is proposed to obtain near optimal IRS phase shifts. Simulation results demonstrate that the proposed algorithm can almost achieve the performance upper bound with a fast convergence rate.