Emilie Masson

Radio Wave Propagation in Arched Cross Section Tunnels – Simulations and Measurements

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.

Radio wave propagation in curved rectangular tunnels at 5.8 GHz for metro applications

The need for wireless communication systems is increasing in the transport domain. These systems have to be operational in every type of environment and particularly tunnels for metro applications. These ones can have rectangular, circular or arch-shaped cross section. Furthermore, they can be straight or curved. This paper presents a new method to model the radio wave propagation in straight tunnels with an arch-shaped cross section and in curved tunnels with a rectangular cross section. The method is based on a Ray Launching technique combining the computation of intersection with curved surfaces, an original optimization of paths, a reception sphere, an IMR technique and a last criterion of paths validity. Results obtained with our method are confronted to results of literature in a straight arch-shaped tunnel. Then, comparisons with measurements at 5.8 GHz are performed in a curved rectangular tunnel.

Robust and High Data Rate Wireless Link for Security Between a Bus and a Control Centre

For transport operators today, making passengers and crews feel safer on urban mass transportation systems, and curbing damage to rolling-stock, are two of the main priorities. To satisfy these needs, they rely more and more on surveillance systems based on audio and video sensors which are able to detect automatically potentially dangerous situations and to send an alarm signal, with the corresponding audio and video streams, to the security staff at the control centre. When the system is embedded in a public transport vehicle, the transmission system must be a wireless one and must be able to offer high data rate and high quality of service in order not to cause a deterioration to the audio and video stream. The work presented in this paper concerns the development of such a transmission system from an urban bus to a control centre. Existing telecommunication standards offering large radio coverage generally offer asymmetrical links and none of them is able to support very high data rate in up-link. The new IEEE802.16 or WiMAX (worldwide interoperability for microwave access) standard will offer 3 to 5 Mbps on both transmission directions. The paper will present a 2x4 MIMO transmission system based on the physical layer called PHY-OFDM of IEEE802.16-d with STBC code and turbo processing to increase robustness. Different signal processing solutions were evaluated in simulation with measured propagation channels with various correlation degrees (suburban and urban canyon) representative of urban bus environments. A real transmission system has been built on the basis of the simulation one. Experiments in real conditions were conducted in the centre of Lille in the north of France.

Radio wave propagation in curved rectangular tunnels at 5.8 GHz for metro applications, simulations and measurements

Nowadays, the need for wireless communication systems is increasing in transport domain. These systems have to be operational in every type of environment and particularly tunnels for metro applications. These ones can have rectangular, circular or arch-shaped cross section. Furthermore, they can be straight or curved. This article presents a new method to model the radio wave propagation in straight tunnels with an arch-shaped cross section and in curved tunnels with a rectangular cross section. The method is based on a Ray Launching technique combining the computation of intersection with curved surfaces, an original optimization of paths, a reception sphere, an IMR technique and a last criterion of paths validity. Results obtained with our method are confronted to results of literature in a straight arch-shaped tunnel. Then, comparisons with measurements at 5.8 GHz are performed in a curved rectangular tunnel. Finally, a statistical analysis of fast fading is performed on these results.

Satellite channel modelling using a Ray-tracing Tool for train communication

Pushed by international trends to develop intelligent transport systems, railways operators rely more and more on new information and communication technologies to optimize exploitation and maintenance costs but also to enhance the friendliness, comfort and security feeling of public transport by offering new services to passengers while traveling. There is not a lot of study dealing with this problem of high data rate services both in uplink and downlink directions in the case of high-speed trains. In our work we consider a double links architecture (terrestrial and satellite) with possible switch between the links versus availability. The paper focuses on satellite channel modelling. Several models have been developed to characterize the mobile satellite channel. Some of them are based on different states of signal reception. In this paper, the characterization with a 3D ray-tracing tool, of an existing mobile satellite communication channel model, the Karasawa model, based on a three states Markov chain, will be presented

Broadband Internet Access on board High Speed Trains, A Technological Survey

Advances in information and communication technologies lead to the adoption of wireless communications in all sectors, including railway domain. Wireless communications for railway can be used for several applications, requiring safety, reliability, availability, high capacities, etc. Furthermore, wireless communications have been deeply integrated into people’s life and current public telecommunication services increased the needs for mobility services. Railway domain is more and more competitive and it becomes crucial for railway operators to make additional revenue by offering more comfortable and pleasant travels thanks to new on board services. Thus, broadband Internet access on board trains has become, in recent years, an essential and highly expected service in the railway domain. This paper aims at presenting the different technologies that can bring an Internet access on board High Speed Trains.

Measurements and simulations comparisons of radio wave propagation in arch-shaped tunnels for mass transit applications

Wireless communication systems are deployed for train to infrastructure communication needs related to guided transport applications (train, metro, tramway). These systems have to be operational in all transport environments and particularly in tunnels. Realistic tunnels geometries are generally of rectangular cross section or arch-shaped. Furthermore, they are mostly curved. This paper presents measurement results realized in a straight arch-shaped tunnel at 2.4 GHz and 5.8 GHz. The influence of transmitter-receiver location is studied. A statistical analysis in terms of slow and fast fading is realized. The measurement results are compared to simulation results with a modified Ray Launching method in order to validate the modeling approach proposed.

Railway Applications Requiring Broadband Wireless Communications

This chapter is dedicated to all the railway applications requiring broadband wireless communications. The works focus especially on the way to provide Internet access on board trains. The different technologies are reviewed, regarding initial research projects, architectures and existing deployed solutions.

Challenges and Perspectives for the Future Broadband Wireless Communications for Railway

This chapter presents the challenges and perspectives for the future broadband wireless communications for railway. First of all, a section is dedicated to the next generation broadband technologies, such as Cognitive Radios and 5G technologies.

Railway Operators Needs in Terms of Wireless Communications

This chapter is dedicated to the railway operators needs in terms of wireless communications, through railway communication standards, safety aspects and classifications of the applications. Then, the chapter details the operational needs for communication and signaling systems or monitoring systems. Finally, the chapter highlights the needs for services to passengers, though the Internet access on board especially.