Maximizing Secrecy Rate in IRS-Assisted Wireless Systems based on Modified Quantum Particle Swarm Optimization Algorithm

In the modern wireless communication system with multiple antennas located, the presence of eavesdroppers has threaten the security of the entire system. Aiming at the problem of inaccurate phase shift matrix design, we propose an innovative algorithm based on quantum particle swarm optimization to optimize the phase shift matrix of the intelligent reflecting surface. Furthermore, to decrease the problem of unreasonable adjustment of source transmit covariance matrix parameters, we explore a novel precoding and decomposition technology to optimize the beamforming vector. In addition, by using precoding technology, we improve a QPSO strategy to successfully suppress the influence of eavesdroppers and enhance the capacity of legal channels. Simulation results have testified that under low power conditions, our algorithms are significantly better than traditional schemes in terms of secrecy rate performance.