Considerations regarding the radio design of GSM-R systems, inside railway tunnels

The paper describes in detail an entirely original radio design procedure, suitable to calculate and optimize the radio coverage of GSM-R(ailway) systems inside arbitrarily shaped railway tunnels. One of the major issues in modelling radio waves propagation inside railway tunnels is the accurate representation of tunnels´ geometry in the format of digital raster maps, which are used to model indoor terrain features, by the Geographical Information System (GIS) embedded in the radio planning software ICS Telecom ® (produced by ATDI SA), used throughout the radio design procedure presented herein. The production of the tunnel digital raster maps relies on a very simple and also original engineering method, which converts the large scale situation plans of the railway tunnels, readily available at the railway infrastructure operators in electronic format (Autocad), to the desired raster map format, with a 0.1 meters resolution. The last section of the paper describes in detail the selection and configuration of the indoor radio propagation models and presents the results of the radio design procedure. The whole approach of the paper is highly practical, being presented as a radio design case study, for the “Dealul Negru” railway tunnel, situated on the Braşov - Sibiu railway corridor.