Investigation and Optimization of Secrecy Capacity for Intelligent Reflective Surfaces-Assisted Secure mmWave Indoor Wireless Communication

This paper investigates the secrecy performance of an intelligent reflective surface (IRS)-assisted 28 GHz indoor system where the IRS is capable of adjusting the direction and phase shift of reflected signal on its surface and assists a source to communicate with an authenticated user in the presence of a passive eavesdropper. IRSs being promising candidates for millimeter-wave (mmWave) and 6G communication, their deployment has tremendous challenges due to severe information leakage of beam misalignment and costly implementation of continuous phase control. We propose the design of a tile-allocation-and-phase-shift-adjustment strategy for the IRS to optimize the secrecy capacity. In addition to the alignment strategy, the optimal placement to achieve the maximum secrecy capacity is also evaluated through ray-tracing algorithm. Results demonstrate that the proposed IRS-assisted secure algorithm can significantly improve the secrecy capacity performance for an indoor media commutation network.