Double-RIS assisted MIMO V2V channels: Modeling, simulation, and correlation statistics analysis

In this paper, we propose a three-dimensional (3D) elliptical cylinder multiple-input multiple-output (MIMO) stochastic channel model assisted by double reconfigurable intelligent surfaces (RIS) for the vehicle-to-vehicle (V2V) propagation environment. The double-RIS is deployed on building surfaces to reduce signal attenuation and assist the mobile terminal (MT) in reflecting its signals towards the mobile receiver (MR). In the proposed channel model, we incorporate the complex channel impulse responses (CIRs) resulting from multi-path propagation for all four links, thereby deducing the complete channel matrix. Additionally, we derive statistical characteristics, including spatial cross-correlation functions (CCFs), temporal auto-correlation functions (ACFs), and frequency correlation functions (FCFs). Simulation results are presented to illustrate the propagation characteristics of the double-RIS assisted MIMO V2V elliptical cylinder channel model, which clearly indicate that the double-RIS outperforms the single-RIS in channel characteristics, underscoring the importance of introducing double-RIS into the V2V channel model.