Jaizki Mendizabal

Characterization of the EM environment of railway spot communication systems

Trains require spot communication systems to be supervised and controlled. EM interferences in their vicinity could cause their malfunction. Nowadays, the electromagnetic environment of these systems is being researched, but it is not well characterized yet. One of the most relevant origin of these interferences are the electromagnetic fields generated by the train itself. This work presents the measured signals of the EM fields generated by the common mode currents in the traction system and by the contact discontinuities between the pantograph and the catenary. The EM environment analysis is focused on the frequency range of the ASFA and ERTMS BTM systems.

Eurobalise-Train communication modelling to assess interferences in railway control signalling systems

The evolution of the railway sector depends, to a great extent, on the deployment of advanced railway signalling systems. These signalling systems are based on communication architectures that must cope with complex electromagnetical environments. This paper is outlined in the context of developing the necessary tools to allow the quick deployment of these signalling systems by contributing to an easier analysis of their behaviour under the effect of electromagnetical interferences. Specifically, this paper presents the modelling of the Eurobalise-train communication flow in a general purpose simulation tool. It is critical to guarantee this communication link since any lack of communication may lead to a stop of the train and availability problems. In order to model precisely this communication link we used real measurements done in a laboratory equipped with elements defined in the suitable subsets. Through the simulation study carried out, we obtained performance indicators of the physical layer such as the received power, SNR and BER. The modelling presented in this paper is a required step to be able to provide quality of service indicators related to perturbed scenarios.

Virtual Laboratory for On-board ETCS Equipment

Available ETCS equipment suffered from a long process before being put into service, due to inconsistencies in the specifications and the inability of the laboratory certification procedures to completely address all the needs of the system testing. To overcome those problems, this paper presents a novel ETCS Testing Laboratory, which will help in the reduction of on-site testing amount, and a Golden Reference Model of the ERTMS on-board equipment, that will help in the interpretation of the current normative. The design, implementation, operation and validation of these developments will be presented in this research work.

Implementation and validation of an Angle of Arrival (AOA) determination system

This paper presents the implementation and validation of a complete AoA (Angle of Arrival) system. The AoA system is typically used together with smart antenna technology. In this paper the AoA system is part of a mobile wireless communication positioning system. The implementation includes the array antenna, the front ends and the AoA estimation block, which uses the MUSIC algorithm. Furthermore, a complete AoA system model has been developed, and used to find the optimum configuration of the AoA system. The AoA system has been validated using the model implemented in MATLAB.

Design for test of a low power multi-standard GPS/GALILEO RF front-end

This contribution deals with the complete design of a multi-standard GPS/GALILEO front-end, from setting the specifications through to the complete characterization of the device. Special focus will be given to the design for test and the characterization of the design, as optimizing the time spent on this improves time-to-market for the product under development. The highly integrated, low power GPS/GALILEO front-end is designed with a low-IF architecture. The front-end exhibits a voltage gain of 103dB with a power consumption of 66mW from a 3V voltage supply and 38mW if the internal dual-gain LNA is switched OFF. The SSB noise figure of 3.7dB which makes it suitable for high sensitivity applications. Te implemented architecture allows 3 different configurations, adding flexibility to its future applications.

On-Board Electromagnetic Interference Field-Test and Evaluation of a Non-electrified Railway Regional Line

In order to assess the performance of the wireless communication systems, a railway line is characterised through the identification of electromagnetic interferences (EMI). The aim of this paper is to show the strategy to identify EMI on field as well as the results obtained. First, the need of the analysis and the objectives of the measurement campaign in a non-electrified Italian Regional Railway line between Caligari and San Gavino are shown. After that, the measurement setup developed for the tests is described. Then, the description of the measurement campaign carried out is exposed. Finally, the measurement results are presented. The results show that the frequency bands of GSM, UMTS and Italian 4G are in the frequency ranges where the highest powered signal (around 800 MHz–900 MHz, 1.8 GHz and 1.9 GHz), on the other hand GPS L1 and Galileo E1frequency band is not impacted by any kind of interference signal.

ETCS's Eurobalise-BTM and Euroloop-LTM Airgap Noise and Interferences Review

Wireless communications interfaces are vulnerable to interferers and noise. The effect of interferers and noise in the system will depend on the robustness of the communication system and the criticality of the system. ETCS European Train Control System is a safety-critical system responsible for the train control and command. There are two ETCS constituents installed on the track with a wireless communication to the train, namely Eurobalises and Euroloops that communicate with Balise Transmission Module BTM and Loop Transmission Module LTM. This paper includes an analysis of the state of the art of noise and interferers and proposes the worst case scenarios to be used in the laboratory to measure the robustness of the systems against noise and interferers.

Wireless Communication Emulator Device and Methodology for the ETCS BTM Subsystem

Currently European Train Control System ETCS rollout is a major concern for train manufacturers and railway infrastructure managers. But available laboratory certification procedures do not completely address all the needs of the system, which leads to long and expensive field-testing. This research work proposes a new tool that reduces the required on-site testing amount. The BTM Wireless Communication Emulator WCE reproduces the potential interferers that can be found in the air-gap of the BTM wireless communication channel. That way, the laboratory testing procedures can emulate the behavior of the wireless channel in a more realistic way. The identification of the potential interferers to be included in the emulator has been done first, and the design and implementation has been carried out afterwards. Finally, the testing and validation of the tool has been completed.

EMC precertification laboratory for railway communication equipment

This paper deals with the definition of an EMC precertification laboratory for communication equipment for railway systems. The main objectives are to show to 5th year telecom engineering students how to build an EMC precertification laboratory based on the applicable standards and introduce them into the tests executions and results interpretation. For that, first, it briefly explains why certification of the electronic equipment is required for these systems. The standards and norms relating to EMC certification and its tests are then presented, and there follows a summary of lab definition and a description of the different kinds of testing. Finally, this work concludes that an in-house laboratory can be defined in order to precertify any communication equipment for the railway industry and therefore it is important for telecom engineering student to have dealt with.

Analysis of YouTube’s traffic adaptation to dynamic environments

The popular Internet service, YouTube, has adopted by default the HyperText Markup Language version 5 (HTML5). With this adoption, YouTube has moved to Dynamic Adaptive Streaming over HTTP (DASH) as Adaptive BitRate (ABR) video streaming technology. Furthermore, rate adaptation in DASH is solely receiver-driven. This issue motivates this work to make a deep analysis of YouTube’s particular DASH implementation. Firstly, this article provides a state of the art about DASH and adaptive streaming technology, and also YouTube traffic characterization related work. Secondly, this paper describes a new methodology and test-bed for YouTube’s DASH implementation traffic characterization and performance measurement. This methodology and test-bed do not make use of proxies and, moreover, they are able to cope with YouTube traffic redirections. Finally, a set of experimental results are provided, involving a dataset of 310 YouTube’s videos. The depicted results show a YouTube’s traffic pattern characterization and a discussion about allowed download bandwidth, YouTube’s consumed bitrate and quality of the video. Moreover, the obtained results are cross-validated with the analysis of HTTP requests performed by YouTube’s video player. The outcomes of this article are applicable in the field of Quality of Service (QoS) and Quality of Experience (QoE) management. This is valuable information for Internet Service Providers (ISPs), because QoS management based on assured download bandwidth can be used in order to provide a target end-user’s QoE when YouTube service is being consumed.