Time-Varying Channel Modeling for Low-Terahertz Urban Vehicle-to-Infrastructure Communications

In this paper, the V2I channel in a typical urban scenario is analyzed by the ray tracing technique at 110 GHz. The channel statistics, including the path loss, time-of-arrival (ToA), and direction-of-arrival (DoA) are thoroughly characterized. To capture the channel non- stationarity, a continuous-time birth and death (B-D) process is utilized to model the dynamic behavior of multiple path components (MPCs). On the basis of the channel statistics from the ray tracing combining the B-D process, a geometric-based stochastic time- varying model (GBSTM) is developed for the low-THz urban V2I scenario, which considers the spherical wave propagation and specular MPCs. The closed-form expressions for the critical statistical quantities of non-stationary channels, e.g., the four- dimensional (4D) time-frequency correlation function (TF-CF) and time- frequency dependent power delay profile (TF-PDP) are derived. The analysis reveals that spherical wave propagation will cause non- linear temporal-spatial correlation and extra non- stationarity of the channel in the time domain.