A 3D Wideband Non-Stationary GBSM for RIS-Assisted Communications in Outdoor Scenarios

In this paper, we propose a novel three-dimensional (3D) wideband non-stationary geometry-based stochastic model (GBSM) for reconfigurable intelligent surface (RIS)-assisted communications in outdoor scenarios. To mimic a more realistic outdoor environment, we introduce a twin-cluster model and consider the evolutions of clusters in time and antenna domain. The proposed model is a combination of transmitter (Tx)-RIS-receiver (Rx) reflection components and Tx-Rx components. Based on the proposed model, some key statistical properties like power delay profile (PDP), achievable rate, temporal autocorrelation functions (ACFs) are derived and analyzed. The simulation results demonstrate the correctness of the proposed model and the non-stationary property. Although imperfections in phase knowledge acquirement are existed in real world, the use of the RIS still makes appreciable improvements in the communication system performance according to the simulations.