Characterization of the propagation channel in a high speed train environment

High speed train (HST) lines are now developing rapidly and one of the aim of European Programs is to be sure that the future Unified Mobile Telecommunication System (UMTS) working with a carrier frequency of about 2 GHz and a data rate of 2 Mb/s could be in operation in such trains. Extrapolation of other theoretical and experimental results obtained on roads or in towns is not obvious due to the specific environment of HST lines since the terrain, especially in hilly countryside, has been made up to minimize the slopes and the bends. Therefore deep cuttings, which can be covered near the town, long tunnels, bridges and underground stations are frequently encountered. The characterization of the propagation channel in tunnels and in stations is emphasized and both theoretical and experimental results of narrow band and wide band analysis are presented.