Abstract:

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.

Key words: physical layer security, intelligent reflecting surface (IRS), multiple input multiple output (MIMO), artificial noise, Riemannian manifold optimizaiton