Measurement, Simulation, and Characterization of Train-to-Infrastructure Inside-Station Channel at the Terahertz Band

In this paper, we measure, simulate, and characterize the train-to-infrastructure (T2I) inside-station channel at the terahertz (THz) band for the first time. To begin with, a series of channel measurements is performed in a train test center at 304.2 GHz with 8 GHz bandwidth. Rician K-factor and root-mean-square (RMS) delay spread are extracted from the measured power-delay profile. With the aid of an in-house-developed ray-tracing (RT) simulator, the multipath constitution is physically interpreted. This provides the first hand information of how the communicating train itself and the other train on site influence the channel. Using this measurement-validated RT simulator, we extend the measurement campaign to more realistic T2I inside-station channel through extensive simulations with various combinations of transmitter deployments and train conditions. Based on RT results, all cases of the target channel are characterized in terms of path loss, shadow fading, RMS delay spread, Rician K-factor, azimuth/elevation angular spread of arrival/departure, cross-polarization ratio, and their cross correlations. All parameters are fed into and verified by the 3GPP-like quasi-deterministic radio channel generator. This can provide the foundation for future work that aims to add the T2I inside-station scenario into the standard channel model families, and furthermore, provides a baseline for system design and evaluation of THz communications.