Channel analysis for millimeter-wave railway communications in urban environment

Due to the convenience and flexibility brought by railway traffic, more and more people prefer to using it for travel. One of the vision of 5G network is to support high-mobility users with high-data-rate connection, which brings challenges to the system design of the HSR communication system. Millimeter-wave (mmWave) technologies are considered as candidates to provide wide-band communication, however such high frequency band is rarely explored in HSR scenarios. In this paper, channel characteristics are studied in the 5G mmWave band for typical urban HSR scenarios, including straight and curved route shapes. Through extensive ray-tracing simulations for 500 MHz bandwidth centered at 25.25 GHz with equivalent beamforming radiation pattern, path loss is modeled and breakpoint is observed. Delay spread, Rician K-factor, Doppler effect and coherence time are analyzed and suggestions are provided to guide the 5G mmWave communication system design for HSR urban communication.