Paul Unterhuber

A Survey of Channel Measurements and Models for Current and Future Railway Communication Systems

Modern society demands cheap, more efficient, and safer public transport. These enhancements, especially an increase in efficiency and safety, are accompanied by huge amounts of data traffic that need to be handled by wireless communication systems. Hence, wireless communications inside and outside trains are key technologies to achieve these efficiency and safety goals for railway operators in a cost-efficient manner. This paper briefly describes nowadays used wireless technologies in the railway domain and points out possible directions for future wireless systems. Channel measurements and models for wireless propagation are surveyed and their suitability in railway environments is investigated. Identified gaps are pointed out and solutions to fill those gaps for wireless communication links in railway environments are proposed.

Measurement and Analysis of ITS-G5 in Railway Environments

In this paper we present first measurement results of a novel approach in Train-to-Train T2T communications. For this measurement campaign an Intelligent Transport System ITS-G5 communication link was used to investigate the influences of a railway environment on a Car-to-Car C2C communication standard based system. The measurements cover a wide range of scenarios from urban to rural environments, forest to open field as well as tunnels and crossings under bridges. The investigated measurement categories are channel characteristics, system performance and environmental aspects. The results should clarify, if a technology transfer from road to railway traffic communications would be expedient.

First analysis of inside Train communication with ITS-G5 measurement data.

Interest in wireless communication systems in the vehicular domain is growing apace leading to the adjustment of current standards to be suitable for the more challenging and varying channel conditions. These adjustments lead to the introduction of the standards Global System for Mobile Communications - Railway (GSM-R), Long Term Evolution - Railway (LTE-R) and Intelligent Transport Systems operating in the 5 GHz frequency band (ITS-G5). First measurement results of ITS-G5 based communications for Intra-Train scenarios are presented in this paper. The performance of an ITS-G5 data link is analyzed and influences on the propagation channel from the inside and outside environment of the train are investigated for different link distances and different speed. The results show the possibility of applying such technology for Intra-Train communications for future wireless applications.

ITS-G5 Channel Models for High Speed Train-to-Train Communication

Train-to-train communication will be the key technology for future railway operation. An increase of safety and efficiency can be achieved by exchanging data between trains via ad hoc networks. For vehicle-to-vehicle communication the European standard is intelligent transport systems (ITS-G5). The usage of this standard for railways is hardly investigated. We investigate the performance of ITS-G5 for train-to- train communication at high speed conditions. ITS-G5 units were installed on two high speed trains and train-to-train (T2T) measurements were performed between Naples and Rome during four nights to cover different maneuvers. We present the analysis of the measurements data and resulting path loss models for tunnel and open field environments.