Global System For Mobile Communications-Railway Research Articles

Extending 5G to Narrow Spectrum Allocations

5G New Radio (NR) has been a great success story since its introduction. It offers high reliability, low communication latency, flexibility, and efficiency that further enable 5G networks to be used for mission critical applications. Currently, there are specialized networks serving industry verticals that would benefit from the NR properties. Key use cases include communications for critical infrastructure such as railways, public safety, and smart energy and infrastructure. These networks often use dedicated spectrum allocations that are narrower than the original minimum operating bandwidth of NR. In this paper, we describe how new flexibility is being introduced into the NR design to allow operation with bandwidths between about 3 and 5 MHz. As a use case study, we focus on railway communications, and study the co-existence of the Global System for Mobile Communications – Railway (GSM-R) and Future Railway Mobile Communication System (FRMCS) based on NR during the decade-long migration period. We discuss the changes required for the NR control channels and signaling and study the effect of the changes on the system performance.

GSM-R wireless field strength coverage prediction algorithm based on PSO-RBF neural network algorithm

In the wake of the successive construction of new railway lines, new lines and existing lines are adjacent, approached and surpassed. In the early stage of line construction, if the influence of adjacent lines is not considered in subsequent planning, the original lines need to be adjusted, and the reconstruction of the base station (BS) coverage along the railway increases the hardness of buliding and the invested funds. Therefore, a Global System for Mobile Communications – Railway (GSM-R) wireless field strength coverage prediction model based on particle swarm optimization (PSO) algorithm optimized radial basis function neural network (RBFNN) was proposed. Aiming at the problem of slow network convergence caused by improper selection of network parameters and structure of RBFNN, PSO algorithm is used to optimize the parameters of RBFNN, and combined with the actual measurement data on site, a PSO-RBFNN model is established to simulate and predict the field strength coverage. The results show that the prediction effect of PSO-RBFNN is the best, followed by RBFNN, and the worst of HATA model, which is very beneficial to the future railway GSM-R wireless network coverage and provides a feasible idea.

Analysis of the possibility of implementing interoperability tests on Polish railways

Ensuring the greatest possible interoperability of rail transport, especially for railways in Europe, is one of the key projects to be implemented using the European Rail Traffic Management System (ERTMS), including the European Train Control System (ETCS) and the Global System for Mobile Communications-Railways (GSM-R). The ERTMS system aims to replace many different rail traffic control systems with one, common and unified European solution (Commission Regulation (EU) 2016/919, 2016), (Directive (EU) 2016/797, n.d.). Its creation was dictated by the desire to standardize the traffic control systems present in the territories of various European countries, at the same time extending their functionality and eliminating the existing technical barriers. The aim of this article is to present the possibility of implementation interoperability tests - IOP tests, on Polish railways. These tests are intended to provide a faster, more accurate and less costly demonstration of compliance with the ETCS interoperability requirements compared to field tests. The work defines the concept of interoperability tests as well as the purpose of their application. The general principles and procedures for conducting interoperability tests are presented. In the further part of the work, the operation of laboratories in the European Union is analysed. The laboratories functional in Switzerland and Spain were selected for this analysis. Following, the paper presents the validity of implementing interoperability tests on the territory of the Republic of Poland. On the basis of the pan-European procedure of conducting interoperability tests and the experience of foreign independent laboratories, conditions for the implementation of tests in the Polish railways were developed, which could be used in the future to introduce IOP tests in Poland.

Railway Wireless Communications Channel Characterization

Railway applications are in continuous evolution with the aim of offering a more efficient, sustainable, and safer transportation system for the users. Generally, these applications are constantly exchanging information between the systems onboard the train and the trackside through a wireless communication. Nowadays, Global System for Mobile communications-Railway (GSM-R) is the technology used by European Train Control System (ETCS), but it is becoming obsolete. Therefore, alternatives for this technology have to be found for the different railway applications. Its natural evolution is to move forward with the latest technology deployed: Long-Term Evolution (LTE), which the Public Land Mobile Networks (PLMN) have already deployed. Therefore, testing the performance of this communication technology in the railway environment could be useful to assess its suitability and reduce the cost of railway network dedicated deployment. In order to do that, a methodology to characterize the communication environment is proposed. The main goal is to measure geolocated impairments of any communication channel in a railway environment being able to determine its behavior of the different communication technologies and find out possible coverage issues. Moreover, it could help in the selection of suitable communication technology for railway. This paper presents a brief description of the communication for railways and its QoS parameters for performance measuring. Afterward, the testing methodology is described, and then, the communication channel measurement campaign on a real track in Spain where the railway environment is variable is presented (tunnels, rural/urban area…). Finally, the measurements and results on this real track in Spain are shown. The results provide suitability of the 4G technologies based on the delay requirements for the implementation of ETCS over it.

RoF distributed antenna architecture- and reinforcement learning-empowered real-time EMI immunity for highly reliable railway communication.

Highly reliable wireless train-ground communication immune to the electromagnetic interferences (EMIs) is of critical importance for the security and efficiency of high-speed railways (HSRs). However, the rapid development of HSRs (>52,000 km all over the world) brings great challenges on the conventional EMIs mitigation strategies featuring non-real-time and passive. In this paper, the convergence of radio-over-fiber distributed antenna architecture (RoF-DAA) and reinforcement learning technologies is explored to empower a real-time, cognitive and efficient wireless communication solution for HSRs, with strong immunity to EMIs. A centralized communication system utilizes the RoF-DAA to connect the center station (CS) and distributed remote radio units (RRUs) along with the railway track-sides to collect electromagnetic signals from environments. Real-time recognition of EMIs and interactions between the CS and RRUs are enabled by the RoF link featuring broad bandwidth and low transmission loss. An intelligent proactive interference avoidance scheme is proposed to perform EMI-immunity wireless communication. Then an improved Win or learn Fast-Policy Hill Climbing (WoLF-PHC) multi-agent reinforcement learning algorithm is adopted to dynamically select and switch the operation frequency bands of RRUs in a self-adaptive mode, avoiding the frequency channel contaminated by the EMIs. In proof-of-concept experiments and simulations, EMIs towards a single RRU and multiple RRUs in the same cluster and towards two adjacent RRUs in distinct clusters are effectively avoided for the Global System for Mobile communications-Railway (GSM-R) system in HSRs. The proposed system has a superior performance in terms of circumventing either static or dynamic EMIs, serving as an improved cognitive radio scheme to ensuring high security and high efficiency railway communication.

Cooperative Prescribed Performance Tracking Control for Multiple High-Speed Trains in Moving Block Signaling System

If high-speed trains move under a moving block signaling (MBS) system, it is a quite challengeable and significant issue to cooperate the multiple high-speed trains, such that they are separated safely and governed steadily. As an intelligent, comprehensive, and advanced modern train operation control system, the MBS system will definitely, in the near future, replace the widely used fixed block signaling system due to its modern communication, multi-source positioning, and advanced control method. Due to the involvement of several subsystems and lots of track-side equipment, such as radio block center (RBC), global system for mobile communications-railway (GSM-R), and so on, it is a nontrivial task to develop a reliable MBS system under complex operational environments, particularly without a pivotally cooperative control method for the movement of multiple high-speed trains. This paper addresses the cooperative control for multiple high-speed trains to achieve prescribed performance tracking, i.e., the speed and the position of high-speed trains are guaranteed to be confined to specific speed limitations and allowed distances ratified by automatic train protection and moving authority, respectively. The proposed control requires no prior information of the empirical parameters of the operational resistances and online adjusts by proper adaptation laws. Theoretical analysis and simulation results are given to demonstrate the effectiveness of the proposed control methods.

Situation-Aware Authenticated Video Broadcasting Over Train-Trackside WiFi Networks

Live video programs can bring in better travel experience for subway passengers and earn abundant advertisement revenue for subway operators. However, because the train-trackside channels for video dissemination are easily accessible to anyone, the video traffic are vulnerable to attacks, which may cause deadly tragedies. This paper presents a situation-aware authenticated video broadcasting scheme in the railway network, which consists of train, on-board sensor, trackside global system for mobile communications-railway (GSM-R) device, WiFi access point (AP), and train control center. Specifically, the scheme has four modules: 1) a train uses its on-board sensors to obtain its speed, location, and received signal strength indicator of train-trackside WiFi channel; 2) the train reports these real-time measurements to the railway control center with the legacy GSM-R networks; 3) according to the measurements, the control center or its WiFi AP adaptively customizes the protected codestream bitrate and AP-train handover time; and 4) the train renders the received codestream, which passes the authenticity verification process. As shown in the performance analysis, the present scheme ensures the codestream authenticity and provides high quality of service in the lossy subway WiFi environment.

Localization of a high-speed train using a speed model based on the gradient descent algorithm

Owing to the problem of weak coverage of private network in the high-speed rail (HSR) environment, the users’ internet perception will be seriously affected by abnormal connection to the ordinary public network. Radio remote unit(RRU) that works abnormally is an important reason for the weak coverage of HSR private network. To address this problem, first, in contrast with the traditional positioning system, such as the global system for mobile communications-railway(GSM-R), we proposed a method that just use HSR user’s information collected by base stations and base station information provided by the telecom operators of China to locate a high-speed train(HST) off-line. Second, an abnormal RRU was detected by using the established speed models based on the gradient descent algorithm. The experimental results showed that the probability of accurately locating the HST was up to 87.17%.

Development Trends of Mobile Communication Systems for Railways

With the widespread deployment of high-speed railways and the increasing speed of trains, timely and reliable wireless transmission of train control signals and passengers' mobile Internet access become critical. To meet these demands, mobile communication systems for railways is shifting from narrowband global system for mobile communications-railway (GSM-R) to broadband systems. In contrast to GSM-R, broadband LTE-R and 5G for railway system could provide more services such as real-time video surveillance, multimedia dispatching and railway Internet of Things. In this paper, we first briefly review the existing GSM-R system and discuss its limitations. Then, we discuss future development of user demands and various data services, which suggests the key performance indicators of the future mobile communication systems for railways. Afterwards, we survey the recent wireless technologies and network architectures that may be applied in mobile communication systems for railways in the near future. Finally, we summarize the technical challenges of future mobile communication systems for railways and conclude this paper.

Broadband Wireless Channel in Composite High-Speed Railway Scenario: Measurements, Simulation, and Analysis

The rapid development of high-speed railway (HSR) and train-ground communications with high reliability, safety, and capacity promotes the evolution of railway dedicated mobile communication systems from Global System for Mobile Communications-Railway (GSM-R) to Long Term Evolution-Railway (LTE-R). The main challenges for LTE-R network planning are the rapidly time-varying channel and high mobility, because HSR lines consist of a variety of complex terrains, especially the composite scenarios where tunnels, cuttings, and viaducts are connected together within a short distance. Existing researches mainly focus on the path loss and delay spread for the individual HSR scenarios. In this paper, the broadband measurements are performed using a channel sounder at 950 MHz and 2150 MHz in a typical HSR composite scenario. Based on the measurements, the pivotal characteristics are analyzed for path loss exponent, power delay profile, and tap delay line model. Then, the deterministic channel model in which the 3D ray-tracing algorithm is applied in the composite scenario is presented and validated by the measurement data. Based on the ray-tracing simulations, statistical analysis of channel characteristics in delay and Doppler domain is carried out for the HSR composite scenario. The research results can be useful for radio interface design and optimization of LTE-R system.

A Step Up in European Rail Traffic Management Systems: A Seamless Fail Recovery Scheme

The European Rail Traffic Management System (ERTMS) is becoming a worldwide de facto standard for high-speed railway signaling. A major shortcoming of this system is that it is attached to a single radio-bearer technology, the Global System for Mobile Communications-Railway (GSM-R). The migration of ERTMS toward Internet Protocol (IP) provides the opportunity to make ERTMS unaware of the underlying communication technology by establishing train-to-ground connectivity via multiple bearers. In this article, we evaluate Multipath Transmission Control Protocol (MPTCP) integration in the ERTMS protocol stack in a test bed as a way to use heterogeneous radio bearers seamlessly and simultaneously. We validate this strategy by comparing our obtained results to the European Integrated Radio Enhanced Network (EIRENE) requirements and demonstrate its functionality as a seamless fail recovery strategy.

NDN-GSM-R: a novel high-speed railway communication system via Named Data Networking

To keep up with the rapid development of railway and meet the high demand for communication business in China, Global System for Mobile Communications-Railway (GSM-R) based on General Packet Radio Service (GPRS) ahead of Europe has been developed. However, the current data communication mode of GPRS using TCP/IP has some disadvantages, such as poor mobility, lack of security etc. For this reason, there are some problems for GSM-R, like handover, which makes communication service quality undesirable. Named Data Networking focuses on named data, adopts data-facing communication mode, and does not care where the contents are stored but the contents themselves. It can effectively solve the problems caused by TCP/IP. In this paper, a new high-speed railway communication system with Named Data Networking (NDN) named NDN-GSM-R is proposed. Two simulations, called transmission interference time and end-to-end transmission delay of NDN-GSM-R, have been conducted. The simulation results show that NDN-GSM-R has better performance in high-speed mobile communication environment and can make up the insufficiency of the current GSM-R based on TCP/IP framework.

VoLTE Performance in Railway Scenarios: Investigating VoLTE as a Viable Replacement for GSM-R

Global System for Mobile Communications-Railway (GSM-R) is the current standard for railway voice and data communication. It provides railway-specific voice services, such as railway emergency calls (RECs), as well as the European Train Control System (ETCS), which offers in-cab signaling and automatic train protection. Despite these features and services, GSM-R has major shortcomings. Therefore, alternative technologies are being considered to replace GSM-R and become the next-generation railway mobile communication network.

Impact of European Railway Traffic Management System on Human Performance in Railway Operations European Findings

The safety of railway system operations depends on several internal and external factors. The former include rail traffic rules, infrastructure, rolling stock reliability, organizational safety culture, and human factors. The railway systems in Europe, North America, and Australasia have seen significant technological developments for improved capacity and efficiency. Europe, for instance, is implementing the European Railway Traffic Management System (ERTMS). However, transition to a more automated traffic management system requires, among other things, changes to infrastructure, rolling stock, operational procedures, or all three. Concerning operational procedures, the literature shows that train drivers, signalers, and controllers have the greatest effect on the safety of a railway network. Therefore, the reliability and safety integrity of the railway network are largely dependent on human factors, in particular, the performance of human operators. This performance in turn is affected by a number of factors broadly known as performance-shaping factors (PSFs), with deficiencies in communication accounting for more than 90% of incidents for the conventional railway system. Therefore, this study investigated the influence of ERTMS and in particular the Global System for Mobile Communications–Railway (GSM-R) on operators’ performance. The study analyzed 74 accident and incident reports of railway operations before and after GSM-R implementation from several European railway organizations. The results identified the communications-related factors that affected human performance in the conventional and upgraded railway system based on the existing railway-PSF taxonomy. Finally, the results showed the positive impact of GSM-R implementation on operators’ performance.

Improving Packet Delivery Efficiency Using Dual 3GPP LTE Communication Modules for Railroad Wireless Communication

As a next generation of Global System for Mobile Communications – Railway (GSM-R), 3rd Generation Partnership Program (3GPP) Long Term Evolution (LTE)/ LTE-Advanced (LTE-A) is considered for railroad wireless communication, i.e., LTE-Railway (LTE-R). Railroad wireless communication has its own requirements and functions since railroad wireless communication is very closely related to safety. In order to meet the requirements of LTE-R and provide high QoS level, it is very crucial to have very small packet delivery delay. Since it is anticipated that it will be difficult to deploy LTE-R network with redundant network architecture like GSM-R due to spectrum shortage, high QoS and reliability of LTE communication is very important for LTE-R. Railroad wireless communication network configuration has very unique characteristics compared to other wireless communication networks. Since train moves on pre-installed fixed track, train movement can be easily measured. In this paper, by exploiting the unique characteristic of railroad wireless communication, an improved packet delivery scheme using dual communication modules for railroad wireless communication is proposed. By using the proposed scheme, almost zero service interruption time during handover can be achieved. Since the protocol architecture of the proposed scheme utilizes the current LTE railroad wireless communication hardware, the proposed scheme can be utilized with minimum modification.

LTE for Railways: Impact on Performance of ETCS Railway Signaling

The Global System for Mobile Communications-Railways (GSM-R) is an obsolete mobile technology with considerable shortcomings in terms of capacity and data transmission capabilities. Because of these shortcomings, GSM-R is becoming the element limiting the number of running trains in areas with high train concentration, such as major train stations. Moreover, GSM-R cannot support advanced data services. Hence, modern technologies, such as long-term evolution (LTE), have to be evaluated as possible railway communication technologies to replace GSM-R in the future. This article analyzes the characteristics of the LTE railway radio access network in terms of eNodeB (LTE base station) density and eNodeB transmission power. Based on this analysis, a set of computer-based simulation scenarios (e.g., OPNET) with varying numbers of eNodeBs is evaluated regarding the achieved transfer delay and data integrity of European Train Control System (ETCS) messages.

Third-Generation Partnership Project Standards: For Delivery of Critical Communications for Railways

The Global System for Mobile Communications-Railways (GSM-R) is a radio telecommunication network and the bearer technology for the European Train Control System (ETCS). Both GSM-R and ETCS constitute the European Rail Traffic Management System (ERTMS). GSM was adopted by the International Union of Railways (UIC) because it was the only system in commercial operation with a great potential to fulfill the requirements for the transport of railway services, although some features had to be added to the standard. However, as time has passed, GSM-R has proven to have capacity limitations, higher costs, and long development cycle times due to the special features built into standard GSM that have reduced the market for GSM-R equipment. These facts, together with the end of industry support by 2025, are motivating the switch to long-term evolution (LTE)/system architecture evolution technology as the new bearer network for railways. LTE provides higher data capacity than GSM and presents a flat architecture, which reduces deployment and maintenance costs as long as standard elements are used. This article provides an overview of third-generation partnership project (3GPP) systems, services, and their standardization status, which should be implemented to support the transport of railway services over a standard LTE network. Additionally, the quality of service (QoS) requirements for the transport of ETCS data control are compared with the QoS provided by LTE.

Shadow Fading Correlation in High-Speed Railway Environments

In the design of diversity and fast handover schemes for high-speed railways (HSRs), a better understanding of the shadow fading correlation properties is required. In this paper, both auto- and cross-correlation models of shadow fading in HSR environments are proposed based on a large set of measurements with 6146 cells in China. The measurements are conducted using a practically deployed and operative Global System for Mobile Communications-Railway (GSM-R) system at 930 MHz to reflect the real conditions of shadow fading in HSR environments. Seven typical HSR environments and the realistic base station (BS) parameters are considered in the analysis. It is found that the decorrelation distance is correlated with the standard deviation (STD) of shadow fading and is generally larger than 100 m in most HSR environments. The cross correlation of shadow fading between two neighboring BSs depends on the BS height and the tilt angle of the antenna, and a heuristic truncated Gaussian distribution model of cross correlation is proposed. The model is validated by the measurements conducted in another operative HSR line. The results can be used to exploit the simulation algorithms to analyze the signal-to-interference-ratio (SIR) properties and to develop new and better handover schemes for HSRs.

Classification of Transient EM Noises Depending on their Effect on the Quality of GSM-R Reception

The Global System for Mobile communications - Railways (GSM-R) is being deployed in different countries to develop an efficient communication-based train control (CBTC) system. GSM-R participates to achieve railways interoperability, replacing noninteroperable CBTC on existing networks and, thus, facilitating cross-border train circulations. GSM-R ensures voice and data transmissions between trains and control centers and also between trains. As any radio equipment, it is subject to electromagnetic (EM) disturbances present in the railway environment. Therefore, the quality of GSM-R transmissions can deteriorate. It is then important to evaluate and predict the effect of these disturbances in order to avoid any loss of train operational capacity. After an overview of the methods used for the characterization of the EM environment, we describe the GSM-R and the EM disturbances that can affect its operation. The reasons why the existing characterization methods are not fully adapted to the GSM-R are highlighted. The general principle of classification is briefly recalled. The rest of this paper develops the methodology proposed to perform the classification of transient EM noises and the presentation of a test bench and its associated experimental results. Finally, an application to an add-on electromagnetic compatibility supervising equipment installed on board the train is described.

Long term evolution in high speed railway environments: Feasibility and challenges

Long Term Evolution (LTE) is considered to be the natural evolution for the current Global System for Mobile Communications-Railways (GSM-R) in high speed railway environments, not only for its technical advantages and increased performance, but also due to the current evolution of public communication systems. In railway environments, mission critical services, operation assistance services, and passenger services must be supported by reliable mobile communication systems. Reliability and availability are key concerns for railway operators and as a consequence, railway operators are usually conservative adopters of information and communication technologies (ICT). This paper describes the feasibility of LTE as a successor to GSM-R for new railway mobile communication systems. We identify key features of LTE as a technology and analyze its ability to support both the migration of current railway services and the provisioning of potential future ones. We describe the key challenges to address specific requirements for railway communication services including the provisioning of voice service in LTE networks, handover performance, multicast multimedia transmission, and the provisioning of group communications service and railway emergency calls.