Secrecy Rate Based Beamforming Optimization Strategy in IRS-Assisted Multiuser CR-SWIPT MIMO System

This paper investigates the joint design and optimization of active beamforming and passive beamforming in intelligent reflecting surface (IRS)-assisted multiuser cognitive radio simultaneous wireless information and power transfer (CR-SWIPT) MIMO system. We address the scenario where the cognitive energy harvesting node could potentially eavesdrop as Eve. Our objective is to maximize the secrecy rate of the cognitive information decoding node, considering constraints such as transmit power control, energy harvesting, phase shift, and maximum tolerable interference power. We propose an inexact block coordinate descent (IBCD) method to solve the nonconvex optimization. Simulation results show that the proposed strategy significantly improves the secrecy rate at the information receiving end in IRS-assisted multiuser CR-SWIPT MIMO system. It achieves 46% enhancement compared to the random phase scheme with maximum transmit power. We verify the effectiveness of the IRS in the system security by analyzing the achievable secrecy rate with different settings.