ISSN : 1796-2021
Volume : 4    Issue : 4    Date : May 2009

Radio Wave Propagation in Arched Cross Section Tunnels – Simulations and Measurements
Emilie Masson, Pierre Combeau, Marion Berbineau, Rodolphe Vauzelle, and Yannis Pousset
Page(s): 276-283
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For several years, wireless communication systems have been developed for train to infrastructure
communication needs related to railway or mass transit applications. The systems should be able
to operate in specific environments, such as tunnels. In this context, specific radio planning tools
have to be developed to optimize system deployment. Realistic tunnels geometries are generally of
rectangular cross section or arch-shaped. Furthermore, they are mostly curved. In order to calculate
electromagnetic wave propagation in such tunnels, specific models have to be developed. Several
works have dealt with retransmission of GSM or UMTS. Few theoretical or experimental works have
focused on 2.4 GHz or 5.8 GHz bands. In this paper, we propose an approach to model radio wave
propagation in these frequency bands in straight arch-shaped tunnels using tessellation in multi-
facets. The model is based on a Ray Tracing tool using the image method. The work reported in
this paper shows the propagation loss variations according to the shape of tunnels. A parametric
study on the facets size to model the cross section is conducted. The influence of tunnel
dimensions and signal frequency is examined. Finally, some measurement results in a straight
arch-shaped tunnel are presented and analyzed in terms of slow and fast fading.

Index Terms
Radio wave propagation, Arch-shaped tunnels, Ray tracing, tessellation, E-field measurements