IRS和人工噪声辅助的MIMO-SWIPT系统安全传输方案设计

针对多天线无线携能通信系统中能量收集节点作为潜在窃听者的信息安全问题，提出了一种智能反射面(Intelligent Reflecting Surface, IRS)和人工噪声辅助的物理层安全传输方案。首先考虑发射功率、能量收集门限以及IRS单位模约束，以最大化系统安全速率为优化目标，在合法用户直射链路不可用的情况下，联合设计发射端波束赋形矩阵、人工噪声协方差矩阵以及IRS相移矩阵，建模一非线性多变量耦合的非凸优化问题；接着利用均方误差准则等价转换非凸目标函数，并利用连续凸逼近方法(Successive Convex Approximation, SCA)处理非凸的能量收集约束；最后基于交替优化框架，分别用拉格朗日对偶方法和基于价格机制的优化最小化(Majorization-Minimization, MM)算法求解发射端变量和IRS端变量。仿真结果表明，与现有方案相比，所提算法能够在保障能量收集需求的同时大幅度提升系统的安全性能。

Design of Secure Transmission Scheme for MIMO-SWIPT System Assisted by IRS and Artificial Noise

For the information security problem of energy reveiver as potential eavesdropper in multi-antenna simultaneous wireless information and power transfer(SWIPT) system,a physical layer security transmission scheme assisted by intelligent reflecting surface(IRS) and artificial noise is proposed.Firstly,considering the transmit power,energy harvesting threshold and unit module constraints of IRS,a nonlinear and multivariable coupling nonconvex problem is established.The beamforming matrix,artificial noise covariance matrix and phase shift matrix at IRS are jointly optimized to maximize the system secrecy rate.Then the nonconvex objective function is transformed equivalently based on mean square error criterion and the nonconvex energy harvesting constraints are treated by Successive Convex Approximation(SCA) method.Finally,the transmitter variables and IRS variables are obtained by Lagrangian dual method and the Majorization-Minimization(MM) algorithm based on price mechanism respectively.Simulation results show that the proposed algorithm can significantly increase the secrecy performance and guarantee the energy harvesting requirement as compared with existing schemes.