IRS与人工噪声辅助的MIMO通信系统物理层安全方案设计

针对多输入多输出通信系统信息传输过程中的安全问题, 提出一种智能反射表面(intelligent reflecting surface, IRS)与人工噪声辅助的物理层安全设计方案。在该方案中, 首先基于系统保密速率最大化准则, 构建一非凸优化问题。由于该问题求解需联合优化设计基站波束赋形矩阵、人工噪声协方差矩阵及IRS相移矩阵,为易于求解, 基于均方误差准则, 对非凸目标函数进行等价转换。最后, 以交替迭代方式分别利用内点法和基于黎曼流形的共轭梯度下降算法, 求解波束赋形矩阵和人工噪声协方差矩阵以及IRS相移矩阵。仿真结果表明, 所提方案的系统保密速率在发送端具有较高的发送功率时, 优于其他几种方案。

Design of physical layer safety scheme aided with IRS and artificial noise for MIMO communication systems

For security issues of multiple input multiple output (MIMO) communication system in the process of information transmission, this paper proposes a physical layer security scheme aided by intelligent reflecting surfaces (IRS) and artificial noise. In this scheme, based on the criterion of maximizing the system security rate, a non-convex optimization problem is first constructed involved with the joint design of base station beamforming matrix, artificial noise covariance matrix, and IRS phase shift matrix. Then, in order to make the optimization problem solvable, the non-convex objective function is equivalently transformed based on the mean square error criterion. Finally, the interior point method and the conjugate gradient descent algorithm based on Riemannian manifold are respectively used to obtain the beamforming matrix, the artificial noise covariance matrix, and the IRS phase shift matrix in an alternating iterative manner. Simulation results show that the system security rate of the proposed scheme is superior to other schemes when the sender has high transmission power.