IRS辅助的安全通信系统波束成形嵌套优化算法

Beamforming Nested Optimization Algorithm for IRS-assisted Secure Communication Systems

智能反射面(Intelligent Reflecting Surface,IRS)是一种通过重新配置无线传播环境,提高无线通信网络安全性的绿色通信新技术。该文针对IRS辅助的多输入单输出安全通信系统,考虑在合法用户保密率约束下,联合优化基站处的发射波束成形和IRS处无源移相器的反射波束成形,使基站的发射功率最小。为了求解多变量耦合的非凸优化问题,我们提出了拉格朗日函数和粒子群嵌套优化算法,使用粒子群算法搜索IRS的反射波束成形,拉格朗日函数求解对应的发射波束成形,获得非凸优化问题的次优解。论文仿真比较了不同算法下基站所需的发射功率,结果表明所提算法基站所需发射功率更低。

Intelligent Reflecting Surface(IRS)is a new green communication technology,improving the security of wireless communication networks by reconfiguring the wireless communication environment.In this work,we propose to minimize the transmit power of the Base Station(BS)for the IRS-assisted multiple-input single-output security communication system.Constrained by the secrecy rate of the legitimate user,we jointly optimize the transmit beamforming at the BS and the reflect beamforming of passive phase shifters at the IRS.A Lagrangian function and particle swarm nested optimization algorithm is proposed to solve the non-convex optimization problem with multi-variable coupling.We search the reflect beamforming at the IRS by particle swarm algorithm and solve the corresponding transmit beamforming by a Lagrangian function.In this way,we can obtain a suboptimal solution to the non-convex optimization problem.Simulations are performed on the required transmit power of the BS under different algorithms,showing that the proposed algorithm requires lower transmitting power.