The 5G-Non-Terrestrial Network Channel in a Railway Environment: Characteristics and Required Subcarrier Spacing

Kurzfassung

The railway industry is specifying the Future Railway Mobile Communication System (FRMCS), which will be the successor of the currently used GSM-R. It is a 5G-based system with the possibility for nonterrestrial networks (NTNs). However, the rail track-side environment introduces several specific impairments for an NTN system. In order to investigate the performance of a 5G-NTN system, a channel model is derived based on the literature, and gaps are identified. The model is defined for different orbits and elevation angles. Implementation alternatives are outlined. The periodic fading introduced by overhead power supply structures, such as portals and power supply poles, is found to have the strongest influence in the railway environment. Using the model in 5G-NTN transceiver simulations, we found that a subcarrier spacing (SCS) of 60 kHz is sufficient for S band, while 240 kHz is needed for Ka band.