Enhanced Secure Wireless Transmission Using IRS-aided Directional Modulation

TL;DR

This paper investigates beamforming strategies in IRS-aided directional modulation networks to enhance secrecy rates, proposing two methods that outperform random-phase IRS and no IRS setups, with notable rate gains.

Contribution

Introduces two novel beamforming methods, Max-SR-GPI and Max-RP-ZFC, for IRS-aided directional modulation to improve secrecy rate performance.

Findings

Proposed methods achieve about 30% rate gains over baseline scenarios.

Max-SR-GPI slightly outperforms Max-RP-ZFC in secrecy rate.

Both methods significantly enhance secure transmission in IRS-aided networks.

Abstract

As an excellent aided communication tool, intelligent reflecting surface (IRS) can make a significant rate enhancement and coverage extension. In this paper, we present an investigation on beamforming in an IRS-aided directional modulation (DM) network. To fully explore the advantages of IRS, two beamforming methods with enhanced secrecy rate (SR) performance are proposed. The first method of maximizing secrecy rate (Max-SR) alternately optimizes confidential message (CM) beamforming vector, artificial noise (AN) beamforming vector and phase shift matrix. The first optimization vector is directly computed by the Rayleigh ratio and the last two are solved with generalized power iteration (GPI). This method is called Max-SR-GPI. To reduce the computational complexity, a new method of maximizing receive power with zero-forcing constraint (Max-RP-ZFC) of only reflecting CM and no AN is proposed. Simulation results show that the proposed two methods harvest about 30 percent rate gains over the cases of random-phase IRS and no IRS, and the proposed Max-SR-GPI performs slightly better than the Max-RP-ZFC in terms of SR, particularly in the small-large IRS.