Reconfigurable Intelligent Surface for mmWave Mobile Communications: What If LoS Path Exists?

Abstract

Reconfigurable intelligent surface (RIS) has been widely discussed owing to its potential in enhancing the communication performance in a low-cost and energy efficient manner. The existing research on RIS-assisted channel modeling is mainly based on the assumption of obstructed line-of-sight (LoS) path between the transceivers. However, what if the LoS path (re)appears in RIS-assisted mobile communications? This letter aims at answering this question by developing a novel non-stationary channel model for RIS auxiliary millimeter wave (mmWave) mobile systems in the presence of alternately disappearing and reappearing LoS path. Based on the proposed channel model, a transmission mode switch scheme at a base station (BS) is developed based on the time-varying location of the receiver. The mapping relationship between BS transmission mode and receiver location is derived. Numerical results are provided to verify our analysis.