Energy Efficient Robust Beamforming and Cooperative Jamming Design for IRS-Assisted MISO Networks

TL;DR

This paper proposes a novel IRS-assisted MISO network design that maximizes energy efficiency and enhances security through joint beamforming and phase-shift optimization, even under imperfect channel information.

Contribution

It introduces an energy-efficient, secure beamforming and IRS phase-shift design with algorithms for perfect and imperfect CSI, advancing physical layer security in IRS-assisted networks.

Findings

Proposed algorithms outperform benchmarks in energy efficiency.

IRS improves energy efficiency despite CSI uncertainties.

Tradeoff between energy efficiency and secrecy rate is identified.

Abstract

Energy-efficient design and secure communications are of crucial importance in wireless communication networks. However, the energy efficiency achieved by using physical layer security can be limited by the channel conditions. In order to tackle this problem, an intelligent reflecting surface (IRS) assisted multiple input single output (MISO) network with independent cooperative jamming is studied. The energy efficiency is maximized by jointly designing the transmit and jamming beamforming and IRS phase-shift matrix under both the perfect channel state information (CSI) and the imperfect CSI. In order to tackle the challenging non-convex fractional problems, an algorithm based on semidefinite programming (SDP) relaxation is proposed for solving energy efficiency maximization problem under the perfect CSI case while an alternate optimization algorithm based on $\mathcal{S}$-procedure is used for solving the problem under the imperfect CSI case. Simulation results demonstrate that the proposed design outperforms the benchmark schemes in term of energy efficiency. Moreover, the tradeoff between energy efficiency and the secrecy rate is found in the IRS-assisted MISO network. Furthermore, it is shown that IRS can help improve energy efficiency even with the uncertainty of the CSI.