Railway Communication Research Articles

Reducing the Cost of High-Speed Railway Communications: From the Propagation Channel View

High-speed railways (HSRs) have been widely introduced to meet the increasing demand for passenger rail travel. While it provides more and more conveniences to people, the huge cost of the HSR has laid big burden on the government finance. Reducing the cost of HSR has been necessary and urgent. Optimizing arrangement of base stations (BS) by improving prediction of the communication link is one of the most effective methods, which could reduce the number of BSs to a reasonable number. However, it requires a carefully developed propagation model, which has been largely neglected before in the research on the HSR. In this paper, we propose a standardized path loss/shadow fading model for HSR channels based on an extensive measurement campaign in 4594 HSR cells. The measurements are conducted using a practically deployed and operative GSM-Railway (GSM-R) system to reflect the real conditions of the HSR channels. The proposed model is validated by the measurements conducted in a different operative HSR line. Finally, a heuristic method to design the BS separation distance is proposed, and it is found that using an improved propagation model can theoretically save around 2/5 cost of the BSs.

철도 무선통신망 연동 방안 연구

The current railway wireless network uses various communication scheme depending on the section of railway. Therefore, in the train, it is required a specific communication device for the corresponding communication scheme to communicate and exchange data with the control center. To enhance data rate and support various services, LTE-R scheme has been developed for the next generation railway communications. To use both the existing communication and LTE-R schemes, it is required an integration method for encompassing all communication schemes. In this paper, we overview existing railway communications and LTE-R scheme. Then, we develop a network integration method which can be applied by using one terminal in the train. In addition, implementation issues for the integration are also considered.

Acquisition of channel state information in heterogeneous cloud radio access networks: challenges and research directions

As an emerging system architecture, heterogeneous cloud radio access networks (H-CRANs) can improve system capacity, enlarge coverage, and enhance energy/spectral efficiency. Meanwhile, this newborn architecture also brings many open problems for traditional topics, including synchronization, channel estimation, and data detection. In this article, we present a comprehensive analysis on obtaining CSI in H-CRANs. Specifically, we recognize seven challenges in channel estimation that are caused by a large number of channel parameters, heterogeneity of access nodes in H-CRANs, and the time delays among different nodes. Several research directions for handling these challenges are also proposed, for example, array signal processing and channel compression can eliminate the number of channel estimates, while channel prediction and modification for high-speed railway communications and adaptive downlink array from uplink measurements excel in overcoming the non-reciprocity in channel parameters.

Power-space functions in high speed railway wireless communications

To facilitate the base station planning in high speed railway communication systems, it is necessary to consider the functional relationships between the base station transmit power and space parameters such as train velocity and cell radius. Since these functions are able to present some inherent system properties determined by its spatial topology, they will be referred to as the power-space functions in this paper. In light of the fact that the line-of-sight path persists the most power of the received signal of each passing train, this paper considers the average transmission rate and bounds on power-space functions based on the additive white Gaussian noise channel (AWGN) model. As shown by Monte Carlo simulations, using AWGN channel instead of Rician channel introduces very small approximation errors, but a tractable mathematical framework and insightful results. Particularly, lower bounds and upper bounds on the average transmission rate, as well as transmit power as functions of train velocity and cell radius are presented in this paper. It is also proved that to maintain a fixed amount of service or a fixed average transmission rate, the transmit power of a base station needs to be increased exponentially, if the train velocity or cell radius is increased, respectively.

Emulating extreme velocities of mobile LTE receivers in the downlink

Long-Term Evolution (LTE) is expected to substitute the Global System for Mobile (GSM) Communications as the radio access technology for railway communications. Recently, considerable attention has been devoted to high-speed trains since this particular environment poses challenging problems in terms of performance simulation and measurement. In order to considerably decrease the cost and complexity of high-speed measurement campaigns, we have proposed a technique to induce effects caused by highly time-varying channels on Orthogonal Frequency-Division Multiplexing (OFDM) signals while conducting measurements at low speeds. In this work, we illustrate the performance of this technique by comparing the results of LTE measurements at different velocities in a controlled measurement environment. Additionally, we validate this technique by means of simulations, considering one of the scenarios defined as part of the Winner Phase II Channel Models, specifically designed for high-speed train scenarios.

A dynamic energy-saving strategy for green cellular railway communication network

Energy saving is seldom contemplated in cellular railway communication network because safety is always the main focus. However, we analyzed train schedules and determined that the cellular railway network had considerable potential for energy saving. We designed a simple train detection strategy using the handover procedure to initiate power saving. We also proposed a flexible and effective solution based on the mealy-type finite state machine to transit the cell state between an energy-saving mode and a full running mode. The key design principle of the proposed solution consists in forming an orthogonal group and cluster, based on network deployment and train schedules, to simplify the state transition. Our evaluations using a real network deployment led to a significant energy saving of up to 33% with different power-saving strategies and factors.

Base-band involved integrative modeling for studying the transmission characteristics of wireless link in railway environment

Base-band involved integrative modeling method (BIMM) is proposed for studying the transmission characteristics and bit error rate of the wireless communication, in which the transmitting and receiving antennas, wave propagation environment, and the modulation and demodulation modules are modeled and simulated integratively. Comparing with the conventional wave propagation method used in prediction of field coverage, BIMM is capable of taking the interaction between antenna and environment into consideration, and can give the time-domain waveforms of signals in different places of the wireless link, including those in the base-band modules. Therefore, the distortion reason of signal and in what place it happens can be found, and the bit error rate of the wireless communication can be analyzed. The BIMM in this paper is implemented by finite-difference time-domain (FDTD) method and is applied to the wireless link of railway communication. The effect of the electric spark generated by the power supplying network of the express train on the transmitting property and bit error rate is analyzed.

Application of Thermomechanically Treated Ti-Ni SMA

The main fields of the practical application of Ti-Ni-based alloys, with shape memory and superelasticity effects, in engineering and medicine, have been identified in the past decade. There are temperature-sensitive elements for the actuators, damping devices, fasteners, medical instruments and implants (correctors, clamps, stents), for trauma, spine, dentistry, soft tissues and vessels. The development of science and high technologies to produce semi-finished methods (thin-walled tubes, tapes and thin wire), as well as processing methods (laser cutting and welding) of Ti-Ni-based shape memory alloys (SMA) over the last 10 years has contributed to the creation and implementation into practice of more complicated and advanced devices, based on solid and porous shape memory materials. New technologies require not only the creation of fundamentally new shape-memory devices, but also, more importantly, the achievement of the highest possible functional properties (FP) of the SMA, by creating an optimal type of structure by thermomechanical treatment. Techniques for the regulation of FP are different for Ti-Ni SMA of different compositions. For the non-ageing equiatomic and near-equiatomic Ti-Ni SMA, the basic method of FP control is thermomechanical treatment (ТМT), including severe plastic deformation (SPD), forming various structures: from a well-developed recovered and polygonized dislocation substructure to a nanocrystalline structure. In the framework of the scientific direction, fundamental and applied research in the field of SMA thermomechanical treatment (TMT) has been carried out since 1977, by the Shape Memory Alloys Research Group of the National University of Science and Technology MISIS.The present review provides a brief description of the devices running on the shape-memory effect and superelasticity, developed jointly by NUST MISIS and various companies: Globetek 2000 Ltd (Melbourne, Australia); Semashko Central Clinical Hospital of Ministry of Railway Communications; Closed Joint-Stock Company ARMGAS-NT; Scientific-production Enterprise AVTOMATPROM (Moscow, Russia), et al. In addition, it presents the analysis of medical problems that can be solved using data devices, including work items of thermomechanically treated Ti-Ni SMA.

Joint Access Control Based on Access Ratio and Resource Utilization for High-Speed Railway Communications

AbstractThe fast development of high-speed rails makes people’s life more and more convenient. However, provisioning of quality of service of multimedia applications for users on the high-speed train is a critical task for wireless communications. Therefore, new solutions are desirable to be found to address this kind of problem. Current researches mainly focus on providing seamless broadband wireless access for high-speed mobile terminals. In this paper, an algorithm to calculate the optimal resource reservation fraction of handovers is proposed. A joint access control scheme for high-speed railway communication handover scenario is proposed. Metrics of access ratio and resource utilization ratio are considered jointly in the analysis and the performance evaluation. Simulation results show that the proposed algorithm and the scheme improve quality of service compared with other conventional schemes.

The Research of CIR Based on Communication Technology of GSM-R

In order to realize the wireless communication function of railway locomotives, Cab Integrated Wireless communication equipment (referred to as CIR) as the railway wireless communication system in China's railway locomotives equipment, because has powerful functions, high degree of standardization, and flexible operating characteristics emerged. CRI is based on the GSM-R digital mobile communication technology, GPS global positioning technology, 450MHz and 800MHz analog wireless communications technology such as the development of comprehensive in-vehicle communications equipment. It is the ground of GSM-R equipment and 450MHz, 800MHz and other ground equipment, together form a complete rail integrated wireless communications network.

On the Use of Okumura–Hata Propagation Model on Railway Communications

Although Okumura-Hata prediction model has been a widely used model to estimate radio network coverage, its application in railways environment requires validation and additional studies. This paper presents the main results on a study based on measurements campaigns, and identifies significant differences in parameters that characterize the radio propagation in railways environment, for the 900 MHz band. Both the propagation slope and standard deviation measured values are presented in this work. For validation, the developed model setup was used in the radio planning process, setting a live GSM-R pilot network, operating in Portugal.

El paisaje sonoro como cápsula del tiempo: Un proyecto creativo basado en los sonidos de la primera estación de trenes de Cuenca

Este artículo reflexiona sobre la transformación del entorno a través del paso del tiempo y cómo determinadas tecnologías al servicio de una propuesta creativa permiten la preservación y transmisión de una parte significativa de ese efímero patrimonio a generaciones futuras. Dentro de ese propósito general se presenta este proyecto particular orientado a la realización de la síntesis sonora de un paisaje urbano tan concreto como representa la estación de trenes convencionales de Cuenca –ubicada en el centro de la ciudad– que pudiera ser conservado y reproducido como un singular documento de un presente contrastable en el tiempo futuro: una memoria que interpretase el sonido como una cápsula del tiempo. Nuestro paisaje sonoro se realizó con motivo de la llegada oficial del tren de alta velocidad en 2010 a una nueva estación construida en el extrarradio de la ciudad. El objetivo de esta investigación se centró, por tanto, en generar un documento sintético que ofreciera una memoria sonora que reflejara los rasgos significativos sociales, culturales y logísticos del que fue hasta entonces el único símbolo de la comunicación ferroviaria en la ciudad de Cuenca desde 1883 hasta el final de la primera década del siglo XXI.

Analysis of the Communication System SDH Transmission Network Fault and its Maintenance Technology

SDH transmission mode is a new concept of digital transmission. SDH transmission network can not only improve the efficiency of network management, and can greatly improve the utilization of network resources, reduce the management cost and maintenance cost, to ensure that the network operation and maintenance is flexible operation, reliable and efficient. Social and economic development promotes the development of railway transportation in our country, and the combined railway transportation with communication technology, making up a highly digital railway communication network. In the railway communication network, most of which the transmission technology of SDH transmission network has been adopted. SDH transmission network plays an important role in railway communication network.

Quality of service improvement for high-speed railway communications

With the fast development of highspeed railways, a call for fulfilling the notion of communication at “anytime, anywhere” for high-speed train passengers in the Train Operating Control System is on the way. In order to make a realization of that, new railway wireless communication networks are needed. The most promising one is the Long Term Evolution for Railway which will provide broadband access, fast handover, and reliable communication for high mobility users. However, with the increase of speed, the system is subjected to high bit error rate, Doppler frequency shift and handover failure just like other system does. This paper is trying to solve these problems by employing MIMO technique. Specifically, the goal is to provide higher data rate, higher reliability, less delay, and other relative quality of services for passengers. MIMO performance analysis, resource allocation, and access control for handover and various services in a two-hop model are proposed in this paper. Analytical results and simulation results show that the proposed model and schemes perform well in improving the system performances.

Handover Scheme for 5G C/U Plane Split Heterogeneous Network in High-Speed Railway

Being a promising technology for fifth-generation (5G) communication systems, a novel railway communication system based on control/user (C/U) plane split heterogeneous networks can provide a high-quality broadband wireless service for passengers in high-speed railways with higher system capacity, better transmission reliability, and less cochannel interference. However, due to its special architecture where the C-plane and the U-plane must be split and supported by a macro Evolved Node B (eNB) and a phantom eNB, respectively, it would suffer more serious handover problem, particularly in intermacrocell handover, which directly degrades its applicability and availability in high-speed railways. Moreover, no technical specification has been released about this network architecture. Therefore, this paper focuses on redesigning and analyzing technical details and handover procedures based on Long-Term Evolution (LTE) specifications to guarantee the proposed system's practicability and generality and its analytical tractability. To resolve the handover problem, this paper proposes a handover trigger decision scheme based on GM(1, $n$) model of the grey system theory. By this scheme, the received signal quality from the $(N + hbox{1})$th measurement report can be predicted from the $N$th measurement period, and the predicted values can be then utilized to make the handover trigger decision. The simulation results show that the proposed scheme is capable of triggering handover in advance effectively and of enhancing handover success probability remarkably.

The Simulation Analysis of the Signals Collection Model for Railway Locomotive Remote Communication

The locomotive frequency shift signals carry important operation information. In order to achieve reliable detection of the locomotive signals, this paper analyzes the signal characteristics of the locomotive and proposes a railway remote communication signals collection model. The model uses the data mining methods to extract the locomotive frequency shift signals by analyzing the locomotive frequency shift with signal classification technology. The separated signals can obtain the low frequency signals with low-pass filtering and shaping. The algorithm is simulated by MATLAB software. The results illustrate the proposed method can effectively separate and collect the shifted frequency signals with some application value.

GSM-R Communication Experiment Platform

This paper will introduce the general situation of railway communication, expound the necessity of railway GSM-R communication experiment platform construction, analyze the significance and role of practice teaching, especially the content of construction and project are described.

News: Rail EMC study shows need for updated standards

AN ENGINEERING consultancy in York has played an integral part in a European project assessing the way electromagnetic compatibility (EMC) of railway vehicles is measured. This work is important because rolling stock can produce EM emissions that interfere with railway signalling and communications systems and public broadcast services.

A New RBC handover scheme for LTE-R system

RBC(Radio Block Center) handover of high-speed railway impacts greatly on the safety and efficiency of train operation. However, there are still many problems to be solved in the high mobility applications of GSM-R, especially the higher handover failure probability, which seriously degrades the reliability of railway communication. This paper proposes an optimized handover scheme, in which the coordinated multiple point transmission technology is applied to improve the traditional hard handover performance of GSM-R system.

An Expedited WiFi Connection Establishment Scheme for Railroad Wireless Communications

Always on Internet service has become norm and people are able to enjoy anytime, anywhere broadband wireless communication services. With the emergence of smart phone and tablet, wireless network traffic has increased exponentially. Wireless network traffic is expected to continuously increase dramatically as more and more communication capable multimedia devices are expected to be connected to wireless network. In order to offload heavy traffic of cellular network, WiFi has chosen since WiFi normally operates in license exempt bands. 3rd Generation Partnership Program (3GPP) has started study item on 3GPPWiFi interworking in order to alleviate heavy traffic problem. Since WiFi is independent and different wireless technology, 3GPP needs to be specially designed to provide seamless and high quality interworking with WiFi. Long Term Evolution (LTE)-WiFi interworking has a technical challenge of WiFi network detection. A good solution should provide not only fast WiFi network detection but also battery power saving of mobile phones. In this paper, we propose LTE and WiFi interworking scheme for railroad wireless communication. Our solution is able to provide both expedited WiFi connection establishment and battery power saving by exploiting unique characteristics of railroad communication.