gsm r description

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GSM-R Tomorrows communication for todays rail transportation

Nokia Siemens Networks CorporationP.O. Box 1FI-02022 NOKIA SIEMENS NETWORKSFinland

Visiting address:Karaportti 3, ESPOO, Finland

Switchboard +358 71 400 4000 (Finland) +49 89 5159 01 (Germany)

GSM_R_Description_A4_v2.indd 28-1 6/3/08 1:54:53 PM

2/28 GSM-R - Tomorrows communication for todays rail transportation

The additional R stands for Railways and indicates the add-on delta between GSM and GSM-R. This delta consists of the special functionality that has been specified in the official standard EIRENE, for GSM-R, such as group calls and calling with functional numbers.

Nokia Siemens Networks has been involved since the beginning of the standardization and trials for GSM-R and is the number one supplier with projects in most European countries, China, India and Saudi Arabia, as well as pilots in various countries.

The company comprises the former Networks Business Group of Nokia and the carrier-related businesses of Siemens and continues the legacy of two industry champions Nokia and Siemens.

Siemens has been a frontrunner in the communications industry since the mid 19th century, while Nokia pioneered the development of mobile communications and became the world leader in this field.

Our customers require end-to-end solutions; and the pace of their requirements will accelerate in the future. We can help change the way they do business and capture value. We listen to our customers, innovate together and solve our customers most pressing business challenges.

We bring the benefits of scale and global reach, plus a deep understanding of operator business, an industry-leading research and development organization, and a wide range of services, products and solutions to our customers.

But, to succeed in a rapidly evolving communications industry, scale is not enough. Therefore, we are building an organization and culture that constantly evolves to address our customers key challenges and lead industry change.

This paper aims to give an overview of the functionalities provided with GSM-R, the status of GSM-R and a description of the Nokia Siemens Networks solution for the railways.

Introduction GSM-R has been developed in order to meet existing and future requirements

from Railways. As the name indicates, GSM-R is completely based on the GSMstandards in order to ensure that the system will be future proof and to take advantage of the functionality provided for public GSM systems and customers.

Railway specific functionality (EIRENE)

Nokia Siemens Networks value added services

Standard GSM functionality

GSM enhancements for railways (by ETSI)

Figure 1 Nokia Siemens Networks GSM-R solution

Contents

Introduction 3GSM-R market and standardization 4Requirements for present and future communication systems 6Nokia Siemens Networks solution for railway communication 8Features and applications 10Special requirements on a GSM-R network 18GSM-R Evolution 24Conclusion 26List of abbreviations 27



The current status of GSM-RThe GSM-R infrastructure is, except for a few countries, being rolled out all over Europe. National rollouts have been done in Sweden, Norway, Italy, Spain, Belgium, Switzerland, the Netherlands, and Germany. Nokia Siemens Networks is the major supplier for all these projects and as Radio supplier for Germany. Some regions in India as well as first corridors in Saudi Arabia and China are also equipped with GSM-R.

Trial networks for specification verification (EIRENE/MORANE)

were successfully installed and handed over to customers in Germany, France and Italy. For the MORANE networks Nokia Siemens Networks was the exclusive supplier of the GSM-R Core System (MSC/VLR/HLR/AC/GCR). Also TRAU, BSC and BTS were provided from Nokia Siemens Networks amongst others.

The goal of these pilot projects was to test and validate coverage (especially in tunnels and difficult terrain), EIRENE/MORANE defined applications as well as operating conditions under high speed of the trains for both voice and data transmission.

GSM-R - backgroundRailway operators have lots of different communication requirements for operation and maintenance of their railroad networks, these communication requirements were traditionally met by different technical system solutions. In Europe more than 35 different systems were in use.

In order for the railways to be able to compete with other means of transportation it was found that border crossing of trains must be improved. Until recently changes of trains due to different communication systems were not unusual, thus the average speed of the railway transportation was slowed down significantly.

As some of the systems in use were installed decades ago, are outdated and need to be replaced with new technology, the railway operators saw the need for a future proof digital radio system which fulfils existing requirements as well as new

GSM-R market and standardization

requirements evolving from border crossing train connections, cost effectiveness and quality of service.

Based on the above mentioned the following requirements were identified:

World wide standard with a minimum of modifications for railway which is proven in operation in public mobile networks.Cost effective and economic in realisation and operation.Standardized transmission system components as for the public market (no railway specific implementation to minimize investment).Railway specific services and the radio transmission systems today in use.General requirements for a future railway mobile communication system.Integration of all railway services into one communication network.High reliability and availability, as well as high transmission quality for up to 500 km/h.Ability of smooth integration of new services defined in the future.Interoperable systems in different countries in order to make it easier for trains to cross country borders.

Consequently, the specification task force for EIRENE (European Integrated Railway Radio Enhanced Network), established by UIC

(Union International des Chemins de fer), evaluated candidate systems like GSM and TETRA regarding their functionality. In 1995 UIC selected GSM as the most suitable technology to meet railway requirements and as the basis for the EIRENE specification.

With GSM selected as the basis for the new communication system, railway operators which had specified EIRENE faced two tasks. They needed to define the system requirements and functional requirements that would guarantee interoperability between railway networks.

At an early stage it was established that a common frequency band was a key element for effective international (border crossing) operation of a railway communication system. In 1995 two new frequency bands 876-880 MHz (uplink from mobile) and 921-925 MHz (downlink to mobile) were reserved European wide for EIRENE systems (later called GSM-R-Band) in the CEPT documentTR 25-09. Thus the key requirement for border crossing traffic was resolved and Railways had received 4 MHz spectrum for their radio communication needs which corresponded with 19 different frequencies, each carrying 8 traffic channels.

MORANE (MObile RAdio for Railways Networks in Europe) was

a consortium of railway operators, GSM manufacturers and research organisations. The objective of the MORANE project and its trial sites was to specify, develop, test and validate prototypes of a GSM-R network to ensure that global requirements of the railways were met. The validation was successfully completed. Both EIRENE and MORANE produced during this work a set of specifications to allow individual railways the procurement of fully operational and validated GSM-R products.

UIC also created several new service requests for the GSM-system as work items for ETSI to fulfil the railways requirements for the mobile radio system. These service requests have been standardized within GSM Phase 2+.

In 1997 UIC EIRENE established a Memorandum of Understanding (MoU) within the European Union to introduce GSM-R in the undersigned organisations at least for border crossing traffic. More than 30 UIC members have signed up to this MoU now. The introduction of GSM-R in these countries and railways is a fact and has been going on since 1998.

Links:UIC: http://gsm-r.uic.asso.fr/EIRENE/MORANE: http://gsm-r.uic.asso.fr/specifications.htmlETSI: http://www.etsi.org

Countries with commercial projectsSweden, Norway, Finland, Belgium, the Netherlands, Switzerland, Spain, Italy, Greece, Turkey, Germany, Austria, UK, France, Czech Republic, Lithuania, China, India, Saudi Arabia, Tunisia, Algeria

Countries calling for tender Australia, Hungary, Eurotunnel, Venezuela

Countries preparing for tenderPoland, Portugal, Denmark, Pakistan, Luxembourg, Ireland, Slovakia, Romania, Croatia, Slovenia, Bulgaria, Ukraine, Egypt, Iran, Russia, Belerus and different projects in South America

Figure 2 GSM-R status in February 2008

UIC

EIRENE

MORANEDevelopment and test of a GSM-R system based on the specifications definet by EIRENE

From the requirements for a new common communication standard for the railways

Railway communications Standard body, defines the functional charasteristics and interoperability of GSM-R networks

INDUSTRIALPARTNERS

ETSIETSI-SMG

Figure 3 Specification and validation bodies for GSM-R



Yesterdays railway communication systems

Until recently, most railway telecommunication networks used different systems for the various types of applications needed and users connected. These systems typically belonged to an earlier generation of communication systems. Each application normally

utilized a dedicated communication system for either voice or data communication.

The systems listed below represent some of the most commonly used systems. Many more systems may exist in individual countries.

In most cases these systems used analogue technology and individual frequency ranges and communication protocols. Most of the time, these systems were not interoperable. The consequences were:

Limited applications. Inefficient use of resources (eg. radio frequencies, cabling).High procurement cost (several different systems, no big market for suppliers).High operational cost (power supply, leased line cost).High maintenance cost (service organisation and logistics for each of the systems).Technical evolution almost impossible.Change of radio/train set at border crossing between countries.

The UIC chose GSM-R as the preferred solution and it was specified in EIRENE. The choice of GSM-R by the railway community was motivated by its strong potential to:

Support numerous applications due to the ISDN character of the network.Achieve interoperability.

Service organisation & logistics for only one system.Open for technical evolution (state-of-the-art technology).

The process of defining and standardising requirements that are derived from applications and GSM Phase 2/2+ standards, which define GSM-R, involved railway organisations, railway entities, ETSI and industrial partners.

The functional needs of railways for communication systems can be divided into two sections

EIRENE requirements commonly defined by European railwaysCountry or operator specific requirements deriving from the railway operators needs

One goal for GSM-R was to reserve an European wide radio frequency band in order to realize border crossing of international high-speed and freight trains without change of equipment or stops at national borders. Combined with the standardized EIRENE functionality this guarantees interoperability and seamless border crossing capabilities.

In countries outside of the European Union, frequency bands free for use for GSM-R may differ from the standard GSM-R frequency band due to national regulations (e.g. GSM-R band occupied by military or national security) and have to be agreed upon. GSM-R implementation is still possible, but border-crossing traffic may not be prevented due to different frequency ranges or the availability of mobile terminals operating in different frequency bands. Public GSM frequencies (GSM 850, 900 and 1800) are generally also supported by off the shelf GSM-R products. Other frequencies could be possible as well.

Figure 4 Previous railway applications and the typical used system

Requirements for present and future communication systems

Application Communication system in use

Train Controller Driver Communication

Trunked radio system working at 460 MHz (in England also 200 MHz), e.g. UIC 751-3, BR 1845 (BR 1609)

Automatic train control Railroad based cable (radio transmission at 36/56 KHz), e.g. LZB 80

Shunting teams 80 MHz and 450 MHz radio with walkie talkie functionality

Emergency Communication within an area

Trunked radio system working at 460 MHz (in addition radio systems as used by the local emergency services)

Trackside Maintenance Analogue wired telephone, trackside installed (depending on the coverage, sometimes PLMN-GSM-mobiles)

Train Support Communication Different systems depending on type and importance of the support, often no communication equipment

Wide Area Communication ISDN or analogue networks for voice communication, X.25- and/or LAN for data communication

Passenger Services Analogue mobile radio system, where available. Often no service at all

Local Communication at Station and Depots

PABX networks, analogue 160 MHz radio systems



The GSM-R network, services and structureAs mentioned before, the most suitable technique complying with the requirements in chapter 3 was found to be GSM with some specific railway adaptations. The basic structure of a standard GSM-R network architecture with its interfaces is shown below.

The typical structure of a GSM-R network does not differ much from a normal GSM network in terms of network elements, standardized interfaces and connectivity. The differences exist in the network layout and planning deriving from the critical needs of railway networks.

The same components are used for GSM-R as for GSM meaning that well-proven concepts for HW- and SW-error treatment exist, and this in turn guarantees high system reliability. Also these components are widely spread and the technology is proven and has been in use in public networks for years. Maintenance organisations and distributing channels are available and do not need to be established for railway needs only. This is clearly reducing operation & maintenance efforts for the operator.

Public GSM networks are installed all over the world and they cover more than 80% of the worlds population. This figure is expected to increase with 10% until 2010. There is no question about it, GSM is the leading mobile telephone system worldwide.

GSM-R network elements

Core Subsystem

The Core subsystem consists of: MSC, VLR, HLR, EIR, GCR and AuC

The MSC, Mobile Switching Centre, is the network through which all calls are routed. A network can consist of more than one MSC, for redundancy and/or capacity reasons.The HLR, Home Location Register, is the entity where all subscribers of the network are listed. The phone number and the different services the subscriber is entitled to are defined here.The VLR, Visitor Location Register, keeps track of all subscribers currently connected

to the network. Both subscribers listed in the home HLR as well as visiting subscribers.The EIR, Equipment Identification Register, keeps a list of mobile phones which are to be banned from the network or monitored. This is designed to allow tracking of stolen mobile phones.The GCR, Group Call Register, is a special GSM-R register that defines the areas, numbers and the dispatchers to be connected for different group calls. The area is typically a number of radio cells, the number is a short number defined in the numbering plan and the dispatchers are the train controllers responsible for the area.The AuC, Authentication Centre, is a function to authenticate each SIM card that attempts to connect to the network. An encryption key is generated that subsequently encrypts all communication.

Nokia Siemens Networks switches are based on most successful digital switching system worldwide. All register functions like VLR, HLR, EIR and GCR are realized as software implementations. This gives operators the opportunity to select a flexible structure for the GSM-R nodes depending on network growth and organisational structure. In most cases MSC, VLR, EIR, GCR, HLR and AuC will be installed in one network element. Of course, an operator can also select to split them up into dedicated network elements with further growth of the network or to increase availability. This comprises a very cost effective and maintenance friendly network rollout.

Radio Subsystem

The Radio subsystem consists of: BTS, BSC and TRAU

The BTS, Base Transceiver Station, transmits and receives communication from mobile entities. The closer to a BTS the mobile is the better coverage is provided.The BSC, Base Station Controller, controls a set of BTS. Different methods of connecting BSCs and BTSs gives different network availablities, this is described in chapter 6.1.2.1.The TRAU, Transcoding Rate Adaptation Unit, decodes the communication sent between the Core and Radio subsystems.

Different radio planning aspects are described in the following chapters.

Support Subsystem

Some support subsystem are: IN, SMSC, VMS, CBC, MonC, ABC, AckC, GPRS etc.

The IN, Intelligent Network, is the major entity for additional services. The flexibility of the IN system makes it suitable for customer specific adaptations and services. Many GSM-R specific functionalities have been developed in the IN system.The CBC, Cell Broadcast Centre, sends text messages to all mobiles in a certain cell. Typically the name of the actual radio cell can be broadcasted.The SMSC, Short Message Service Centre, is the subsystem that handles SMS. The VMS, Voice Mail Centre, is the network entity where Voice Mails are stored.The MonC, Monitoring Centre, is a subsystem for recording certain predefined communication. Typically all communication to and from train controllers are recorded for security and post accident analysis.The AckC, Acknowledgement Centre, is a GSM-R specific functionality specified in EIRENE. The data of all Railway Emergency Calls is stored here, such as who participated in the call, when and where the call was set up and duration of the call. The functionality in combination with the MonC can be compared to the Black Boxes that airplanes use for post accident analysis.The ABC, Administration and Billing Centre, is responsible for entering and modifying subscribers into the HLR as well as generating a bill for each subscriber.The GPRS, General Packet Radio Services, transports the Internet Protocol packet services towards data networks such as Internet.

Connected systems

The GSM-R network can connect to various other systems.

Location information systems such as balise systems can be connected. This increases the granularity of Location Dependant addressing for example.Dispatcher systems are train controller systems, similar to flight control. From here the trains

are controlled and route orders are distributed. Large (10-50 train controllers) and small(1-10) train controller centres can be connected. The Dispatcher terminals are either connected via fixed lines or over the radio interface of the GSM-R network.Other voice networks can be connected such as other GSM and GSM-R networks, fixed line networks and company phone networks. This makes it possible to make calls to and from other networks. If roaming agreements are in place it is also possible to use the GSM-R phone in other GSM and GSM-R networks, internationally and nationally. Other Data Networks, typically Internet can be connected just as in normal GSM/GPRS networks.

GSM-R terminals

Different types of mobile terminals are available for GSM-R users.

The CAB radios are permanently installed inside trains. These terminals are often mounded in a rack with a handset and a graphical display. The OPH, Operational Purpose Handheld, are robust mobile phones equipped with GSM-R specific functionality. Their users are thought to be the personnel working in operational mode along the track or in the trains. The GPH, General Purpose Handheld, is the office version of the OPH.The OPS, Operational Purpose Shunting, is designed for personnel that work with shunting. Connecting trains at shunting yards etc. These terminals are designed to stand tougher conditions than the OPH.

Nokia Siemens Networks solution for railway communication

Cell Broadcast

MSC

SMSVoice Mail

IN

BSS

GPRS Service Node

Voice Recording

Centre Subscriber Management

Terminals & Cab Radio

Location dataIT-world input

Other voice networks

Other data networks

Need for a EIRENE compliant network

Dispatchers

Figure 5 Full GSM-system architecture



GSM-R features and applications commonly defined by EIRENEThis subset of communication requirements was studied and identified by representatives of the European railway operators and displays all applications which allow economic operation of Railway communication today and in the future.

Common GSM-R features

A set of applications were defined in EIRENE. In order to realize these applications a set of features were identified. Some of the features were available in GSM and some had to be defined by UIC in EIRENE. Of the below mentioned features eMLPP, VBS and VGCS were already introduced in GSM as the so-called Advanced Speech Call Item (ASCI) and were specified in GSM Phase 2+.

Functional addressing

Many organisations have employees working with daily changing duties. Not only these subscribers but

also applications are addressed by telephone numbers and/or functional numbers/names. Without GSM-R such tables of telephone numbers and functional numbers/names have to be cross-referenced manually to allow identification and connectivity of the person or application subscribing to a particular permanent number.

Functional addressing allows the definition of functional numbers to be performed. These functional numbers represent for example train running numbers and function code. (ref. EIRENE FRS ch11)

At the beginning of a journey or a job the train driver or employee registers his mobile number (MSISDN) to the functional number (FN) of the train. From now on, until deregistration, a call to the train drivers functional number will always be forwarded to the train drivers MSISDN. Since international inter-working is available, the call to the functional number will be processed in any of the participating railway networks.

At the end of the journey or job he may deregister. This applies also for change of direction of the train. If necessary, the network operator can also deregister a subscriber (Forced Deregistration).

Functional addressing is mainly used for ground-to-train communication.

Location dependent addressing

Location dependent addressing provides the automatic routing of Mobile Originated Calls (MOC) to predefined destinations relative to the geographical area where the subscriber is roaming.

The entire network of railways is split into different types of service areas (train monitoring, train control, power supply, substation). A train on a journey, e.g. from Paris to Vienna, passes through several of these areas (e.g. Group Call Areas, GCA). A connection between the train driver and the controller of the corresponding area should be easy to establish. The train driver should have no need to dial long numbers after he has decided in which area he is actually driving.

Therefore, the train driver will only dial a short number as defined in the EIRENE numbering plan. This short number will be automatically converted into the corresponding long number(s) of the train controller(s) responsible for the area the train is actually moving through. If a train passes between two controller areas an additional overlapping Group Call Area can be added, or the connection can be made to both controllers.

Nokia Siemens Networks implements two versions of Location Dependent Addressing, HLR based and IN based. Both functionalities are interoperable as required from EIRENE/MORANE. With the IN version external positioning systems can be used in order to increase the granularity of train positions.

enhanced Multi-Level Precedence and Pre-emption (eMLPP)

Railway organisations have high performance requirements on some types of communication. These requirements are the ultimate need for a radio channel and a very fast call setup.

The application ERTMS/ETCS has the need for a continuous data connection. If a handover to neighboring cells is unsuccessful due to congestion on the radio channel, a pre-emption service is necessary to allow immediate access to a traffic channel occupied by a lower priority application.

Railway Emergency Calls need an immediate call setup in the emergency call area, regardless if free radio channels are available or not. A pre-emption service will release ongoing low priority calls to free traffic channels for emergency call setup. In addition, these calls shall be set up in two seconds or less. Therefore a fast call setup is required.

Shunting Communication and Train Support Communication need different priorities than other types of communication. Therefore additional priority levels are required.

Todays GSM networks only provide access class barring as static and queuing and priority as a call-by-call priority call set-up function. These functions are very limited since priority can only be given per base station (access class barring) or per subscriber basis and not be varied depending on the network situation and priority needed. Furthermore, if all traffic channels are used or even congested there is no other option than to wait with the high priority call in a queue until a traffic channel can be applied.

Figure 7 Location Dependent Addressing

MSCIN or HLR

MSC establishes connection to the full telephone number associated with the right Cell ID

Controller A

Controller B

Figure 8 Allocation of priorities in EIRENE SRS ch 10.2

UIC priorityAutomatic answering*

eMLPP priority designation Pre-emption (of)

Railway emergency Y 0 Control-command (safety) and below

Control-command (safety) Y 1 Public emergency, group calls between drivers in the same area and below

Public emergency and group calls between drivers in the same area

Y 2 Railway operation. Control-command information and below

Railway operation (eg calls from or for drivers and controllers) and control-command information

Y** 3 Railway information and all other calls

Railway information and all other calls

N 4 -

* Auto answer only to voice calls to mobile users as defined in (GSM 02.67) (eML PP)** Mandatory for cab radio, optional for other user equipment

Features and applications

Figure 6 Functional Addressing (principal flow)

ControllerCallingFunctional Numbere.g. 2-12345-01

Integration for FN

FN to MSISDN translation

Call established to MSISDN

Functional Addressing uses Functional Numbers (FN) as defined in EIRENE 2 = Call to train 12345 = Train Number01 = Lead driver

IN or HLRMSC



To introduce a ranking in priority, up to five different eMLPP priority levels are specified for a subscriber (0 to 4). One or more priority levels can be assigned to a mobile subscriber.

Maximum allowed and default priority will be stored in the HLR with the related subscriber data. When an eMLPP priority call is made, the priority of the call will be included in the setup message.

The priority will be evaluated and give access to the appropriate channel for either call setup or handover. High priority calls can get access to resources lower priority users engaged in conversation. This is particularly important in safety critical applications where users must be notified immediately and the high priority call cannot wait in a queue for a free radio channel.

The mobile stations can perform an automatic call hold functionality without user interaction for high priority eMLPP calls that arrive during engagement in another lower priority call. The lower priority call will be put on hold and the high priority eMLPP call will be connected. This improves the ease of handling and the call success rate for high priority calls.

Fast Call Setup

GSM networks with optimized network design allow call set-up times of about 3.5 to 10s depending on network structure

and interaction between mobile station and network. The goal of Fast Call Setup (e.g. for Railway Emergency Call and other group calls) is to shorten the call setup time as much as possible. The current requirements are available in EIRENE FRS v7.0 ch3.4. Nokia Siemens Networks has proved to comply to all those setup times in real GSM-R environments.

Fast Call Setup is basically dependent on call processing time in HLR/AC and MSC/VLR, which have to be shortened. In addition to this authentication and ciphering will be switched off or delayed for these calls.

Automatic Answering

Depending on the priority of a call it should sometimes be automatically answered by the terminal as seen in Figure 8.

Voice Group Call Service (VGCS)

GSM networks are designed for point-to-point connections. Railways and other professional users need the key functionality of point-to-multipoint calls as known from Private Mobile Radio (PMR) or Public Access Mobile Radio (PAMR).

To introduce this into GSM the so-called Advanced Speech Call Item (ASCI) tele-service TS 91, Voice Group Call Service (VGCS) was specified in GSM Phase 2+.

A VGCS call is characterized by the following key points:

One group call number combines all members of a certain group.For each group call a service area composed out of a number of cells is assigned.Dialling the group call number initializes the parallel setup of connections into all cells of the assigned service area. All members of this group being in the service area will be paged and receive a notification of the ongoing voice broadcast call. In parallel all fixed line subscribers that have been defined to be part of the group call will be alerted.Depending on the call ID and priority, members of the group call can decide to join the call or not.

If a group call number is dialled, the MSC recognizes that this number belongs to a broadcast group. The MSC retrieves all necessary information from the collocated Group Call Register (GCR). This GCR stores tables with:

The group ID (one to seven digits depending on the length of the group call area ID).The group call area ID (Country + Mobile Network + Location Area + Cell IDs).The group call reference. The cell list corresponding to the group call area ID (max. 50 cells/MSC).The dispatcher list corresponding to the group call references.Reference information whether or not the call is active per group call.

Information about codecs. Security information. In addition each member of a group call has to have an HLR subscription for this tele-service.

The MSC connects the so called dispatcher with a duplex connection regardless if he is mobile originated or fixed network originated and initializes the setup of half-duplex connections into each cell of the required group call area. Members of the group in this area will be paged and connected via common channel downlink, which means they can only listen to the call if they notify the system that they want to speak by pressing a Push-to-Talk button on the handset.

Group members will normally listen to the ongoing Voice Group Call. As soon as the initiator of the VGCS stops speaking, he indicates that he releases the uplink. All group members will be notified that they can now request an uplink to become the next talker by using their Push-to-Talk button.

If the last talker releases the group call and no new requests are given the MSC releases the VGCS after an administrable time period.

For train controllers a dedicated duplex channel is established, for normal users one common downlink is used and the current speaker uses the uplink in this traffic channel.

If a member of the group enters the cell after the beginning of the group call, they have the ability to join the ongoing group call at his time of entry. If a member of the group leaves the voice group call area, he or she will be disconnected.

The setup of a VGCS is possible with eMLPP or as a normal call without priority and pre-emption.

Voice Broadcast Service (VBS)

To introduce this into GSM the so-called Advanced Speech Call Item (ASCI) tele-service TS 92, Voice Broadcast Service (VBS) was specified in GSM Phase 2+.

The VBS differs from the VGCS in terms of that it is only the initiator and the dispatchers that are allowed to talk. Due to the obvious drawback of unavailable confirmation from the called parties the VBS is rarely used.

GSM-R applications as identified by EIRENEThe figure below gives a short overview of the applications. The applications are based on features available in GSM and GSM-R.

Railway signalling requirements

Automatic train control ATC

Old Train Control Systems have several restrictions:

They are fixed as they are installed alongside the track.Each system needs separate cabling.They are not internationally interoperable.They do not allow high velocity trains with more than 300 km/h.High procurement and operational cost.

The new international interoperable automatic train control system is a European initiative born from the objective to define and introduce a pan European traffic management and train command/control system. The stakeholders are:

The European Train Control System (ETCS) has been implemented as standardized under ERTMS. It is a harmonized modular ATP/ATC system that uses GSM-R as transmission system.

The system introduction is divided into three levels:

LEVEL 1 makes use of the EUROBALISE system (tele-powering from antenna to balise at 27,095 MHz, data transmission from balise to vehicle at 4 MHz/500 kBit/s). It works as an overlay ATP to traditional systems.

LEVEL 2 radio-based Fixed Block System using GSM-R, traditional signals like axle counters, electronic interlocking, line-side signals still in operation. Level 2 is currently being implemented in Europe.

LEVEL 3 radio-based Moving Block System using GSM-R, no other signals in operation

Railway signalling requirements

Operational voicecommunication

Local and wide area(non operational)voice and data communication

Passenger orientedcommunication

Automatic Train Control

Remote Control

Train Controller-Driver Operational communication

Emergency Area Broadcast

Shunting Communication

Driver-Driver operational communication

Trackside Maintenance Communication

Train support Communication

Local Communication at Stations and Depots

Wide area Communication

Passenger Services

Figure 10 GSM-R applications as identified by EIRENEFigure 9 VGCS call

Train is coming please acknowledge that you have heard?

Controller

The Group Area is predefined Train controller initiates a VGCS call in a Group Area The speech is broadcasted to all users

Train is... OK

Train is... OK

Train is... OK



ETCS level 2/3 will be used on high speed tracks allowing train speeds of 350 km/h and above. Therefore GSM-R as the communication channel needs the following characteristics

Bi-directional data flow between fixed ATC-centre and the ATC-computers on the trains over a transparent data channel.Continuous data links for ETCS level 2/3 with burst transmission of data (HDLC-protected).Mobile speed of up to 500 km/h, minimized handover gaps and end-to-end data transfer delay.

With ETCS level 2/3 the ATC computer onboard the train will transmit its position, speed, number of cabs and more train-borne information to the radio block centre (RBC). The RBC network compares data of all trains in the respective area and in turn computes and transmits the necessary speed profile to each individual train. This together with the absence of wired signals finally allows railways to operate their trains with moving block structure and no longer with the traditional fixed block structure. This will reduce the average necessary distance between trains on a single track. The expected

result will be optimized usage of the track and minimized train delays.

ETCS level 2/3 has two principal goals: To reach international interoperability and to optimize usage of the track. The second goal is reached by using a radio system like GSM-R to exchange signalling information. Only without fixed installed signals is a moving block structure for train operation possible. With moving block structure the distance between trains can be kept at a minimum.

All ETCS relevant data are generally transmitted between ETCS trackside and ETCS train-borne application.

This transmission link is, regarding safety criteria, a so-called grey channel, which means, that the safe ETCS equipment uses GSM as the non-safe transport layer.

This non-safe transport layer uses logical redundancy principles and protects ETCS information from random and systematic errors. Thus GSM-R (and EURORADIO) does not need safe hardware. Protection against malicious attacks is possible by using ciphering but this is the decision of the railway operator.

The trains position, speed, number of coaches and other train-borne information will be transmitted to the radio block centre (RBC). Handover between different RBCs is accomplished by having two GSM-R mobiles available on the train for ETCS with each one connected to a RBC. The radio block centre network compares traffic data of all trains in the respective area and transmits the relevant speed profile to each individual train.

Remote Control

The remote control application area comprises rather different applications (one typical application is remote control of shunting locomotives).

In general highly safety-critical actions will be executed and therefore the system has to check continuously (or at frequent intervals) that the communication link is still established. The communications is almost exclusively point to point and coverage is only required over a relatively small area (1-2 km) primarily in stations, yards and depots and only for the period that the remote control operation is in progress.

Operational voice communication

Operational voice communication for railways is mainly realized with standard GSM tele- and supplementary services. The following table outlines the added services and additional functionality from either GSM Phase 2+ and/or EIRENE.

Train radio covers the wide field of railways operational communications characterized by typical functions that were available from trunked radio systems. These functions are available in GSM-R.

Train Controller Driver Operational Communication

The main function of train radio is the communication between a train controller station and the train drivers.

In case the train driver calls the train controller Functional Addressing, Location Dependant addressing and eMLPP will be used.

If the train driver calls a single train Functional Addressing will be used. If the train-driver calls a number of trains VGCS will be used.

Emergency Area Communication

In case of an emergency where railway organisations need to reach all trains, dedicated functions on train and other dedicated railway functions within a predefined area.

A railway emergency call is established either by train functional personnel or train controllers. It is always a VGCS call to a number of cells forming the predefined area.

For security reasons Fast Call Setup (


handhelds and trackside-installed telephones have both GSM-R and public GSM frequency band. The users can thereby roam, if a roaming agreement exists, into a public GSM network if there is no coverage from the GSM-R network.

Since this is not a decided EIRENE functionality it is up to the railway operator to make use of these options. But as already stated, these options are always fully interoperable in the GSM-R system.

Driver-Driver operational communication

Onboard trains there is a need for the leading driver to communicate with other drivers or to connect another driver as a third party into a communication. This may be either established directly via GSM-R as a Multi Party Call or by using the on-board wired system, as applicable for the individual railway.

Local and wide area (non operational) voice and data communication

Local Communication at Stations and Depots

Today local communication at stations and depots generally takes place via railway PABX networks. To improve functionality and connectivity these PABX may be connected directly or remotely to the GSM-R systems MSC/VLR.

Wide Area Communication

Wide Area Communication in a modern railway organisation is typically communication between railway organisational bodies. Today mobility requirements for this type of communication only exist to a certain extent.

Therefore, Wide Area Communication may be regarded as communication with low or no mobility aspects and might not use GSM-R to save capacities for operational purposes. Nevertheless, dependent on the concept of the individual railway, these subscribers can also use GSM-R or be connected in a Virtual Private Network using MSC and IN capacity deriving from GSM-R. Thereby expensive services and subscriptions at public operators can be reduced or eliminated.

Passenger oriented communication

Today, a passenger can only get limited information from the train personnel if he needs typical travel assistance. With GSM-R, information for follow-on connections can be accessible via radio. Furthermore possibilities to book hotels, change reservation or cancel a flight can be available. Taxi reservation, plans of other integrated traffic partners like buses or regional traffic systems and hotel reservation service are other options.

Actual daily information for business travellers like newspaper can also be transmitted via radio to the train.

GSM-R also makes it possible to determine the position of the train and combine this information with other services for passengers.

With high speed data services such as EDGE it is possible to receive large amounts of data and to transmit this data via WLAN (Wireless Local Area Network) to passengers onboard the trains.Please note that local regulations may limit the possibilities for public users to access and make use of the GSM-R network.

Country and operator specific GSM-R applicationsThis subset shows applications typical for a modern railway but not defined by EIRENE. The table below may be extended by additional applications or shortened for those not needed in the individual country/organisation.

Fleet Management

Large amounts have been saved in optimized logistic handling of cars and wagons at different railway organisations.

Passenger Counting

In order to match the amount of cars in correspondence to the amount of passengers passenger counting systems have been developed. The system consists of detectors at every door. The detectors count the number of passengers entering/

leaving the train. The system is connected to a location system that gives the corresponding station.

Passenger Information

Traditional schedules and scheduling systems are normally on paper, CD Rom or accessible via e.g. internet. At railway stations delays of trains are displayed, but not the consequences for follow-on connections. In high speed trains like ICE or other international trains delays and the follow-on connections will be announced by the train driver to the passengers, usually before proceeding to a railway station. Regional and local connecting trains are awaiting these trains and thus additional delays may be caused.

With ETCS train velocity and arrival times can be calculated in a more flexible way. New scheduling systems will take this into account and transmit resulting follow-on connections via data services to the concerned trains thus granting a minimum of delays and a maximum of services and actualities to the passengers. Furthermore, individual calculations of a passenger for its ongoing train journey will be possible provided that equivalent equipment is installed onboard the train.

Video Surveillance

Different areas needs to be under video surveillance. Monitoring stations and platforms for passenger security reasons as well as monitoring the amount of leaves on critical sections of the railway track for maintenance reason are some typical examples. Due to the limited bandwidth either snap shots or low resolution video is suitable.

Train Positioning/Cargo Tracking

Cargo and passenger railways and their partners very often demand to know where the individual freight is travelling at that particular moment and when/how it will arrive at the customer. A freight control system can be established via data services and give information about actual location of the freight and train/wagon.

Online Ticket Sales

Traditionally tickets are either submitted at ticket offices in railway stations, local or foreign traffic bureaus or ticket machines for either credit cards or money.

With existing Personal Digital Assistance (PDA) for GSM-R connected to portable ticket printers and credit card readers on board sales of tickets online can be offered.

At remote stations ticketing machines with credit card readers can be installed connected via GSM-R.

With GSM-R data services or GPRS the railways can improve the services available for passengers in offering them complete travel packets for their journey; pre-booking of a taxi at the final destination, early check-in for luggage for the aircraft and hotel vouchers could additionally be offered. To increase the value of these services the possibility to change bookings on the ongoing journey is available.

Train Diagnosis Monitoring

Train online diagnostics data are collected on the running train (e.g. supervision of brakes, axles, current consumption). When the train returns to its home railway station or a depot, offline diagnostics take place and online diagnostic data will be transferred to the maintenance personnel for evaluation and repair to reduce time spent for repair.

Some diagnostic data will be transmitted in the future under ETCS if they are needed for automatic train control. All other diagnostic data shall be collected on the running train and transferred via radio network whenever needed. For the most applications this will be at the home railway station or inside the depot.

As already mentioned, train diagnostics are not a GSM-R specific functionality. Furthermore this application is highly dependent on the trains in operation and the maintenance concept of the specific operator. Both GSM-R and public GSM have the necessary data services to transmit the relevant data available today.

WLAN/VPN to passengers

WLAN/VPN on Trains is an end-to-end service concept operated by Nokia Siemens Networks. This scenario includes consulting, design, build, operation and maintenance services as well as related customer support services and billing. This will allow railway operators to provide an onboard Internet connectivity towards passengers under their own branding. Different means of transmission is used at different places depending on the availability of those. WLAN, satellite, UMTS etc are examples of transmission techniques that have been used.

Figure 14 Additional GSM-R applications

PassengerCounting

FleetManagement

PassengerInformation

Video Surveillance

Train Positioning/Cargo Tracking

OnlineTicket Sales

Train DiagnosisMonitoring

WLAN/VPN topassengers

Online, low bandwidth, connectivity

via GSM or GSM-R (SMS, GPRS, EDGE)

Broadbandconnection via

Multi access(Satellite, UMTS, EDGE, CDMA, )

Train



Special requirements of GSM-R networks are derived from the following demands on applications:

Seamless communication up to a speed of 500 km/h.Efficient usage of a limited number of frequencies (4 MHz).C/I of 12 dB min (EIRENE requirement 15 dB).95 % coverage for 95 % of the time in a designated coverage area with a level of above -90 dBm.Handover success rate of more than 99.5%.High availability of both transmission path and network equipment depending on the application in use.

Coverage inside tunnels. Improved coverage in railway stations and shunting areas.Call setup times as indicated below in 95 % of all cases, and up to 99 % in less than 1.5 cases of the described period (ref. EIRENE FRS version 7.0, chapter 3.4).

These demands are more or less stringent for the different type of GSM-R applications. In addition it is to be considered, whether the railway wants to roll out a countrywide network or just to equip high speed and international tracks with GSM-R.

Quality requirements of GSM-R

Quality requirements of GSM-R are based on the GSM recommendations QoS (Quality of Services) parameters. Since these are not defined in detail and different railway applications need different QoS, definition of railway QoS is an ongoing process in EIRENE as well as between railways and suppliers.

Some of the parameters and figures presented below will be revised by the QoS Working Group!

QoS requirements of other railway applications are below these values.

Network planning requirements of GSM-R

When planning the railway network, the following criteria must be taken into account:

GSM-R applications and resulting traffic model

Railway network traffic models differ from those in public mobile networks. Subscribers will have more BHCA, SCI and even a longer talk time. Applications like ETCS will even require a traffic channel over the full journey of a train. In turn the number of subscribers is pretty low in comparison with a common GSM network. Features like ASCI VGCS or VBS will have an impact on the traffic model. A typical traffic model of a European railway operator is shown below.

Availability requirementsAs already mentioned, availability of the radio channel is one of the key criteria for GSM-R, especially if ETCS is to be considered. Therefore, redundant network structures have to be built wherever really needed.

Railway topologyA typical railway topology includes flat and hilly terrain. Traditional railtracks contain a number of curves while they are avoided if possible for new tracks. Especially to be taken into consideration are the following conditions:

Deep and/or long cuttings spanned with a bridge.Long tunnels. A series of short tunnels with limited space between.Tunnel materials (natural stone, concrete, concrete with steel) and profile.

Curves and crossings inside the tunnel.

Train speedDepending on the maximum planned train speed the lengths of handover zones need to be planned very carefully.

Railway transmission or site facilitiesIn many cases, railways already have transmission facilities and sites from the traditionally built analogue networks. To reuse these sites a migration concept needs to be established.

Figure 17 Typical traffic model for railway networks

Traffic-SourceCall Type

mErl per MS per BH

CA per MS per BH

active MS

Erl per BH

CA per BH

IN-BHCA

Train radio Voice 80 9 1000 80 9000 9000

Emergency phones Voice 10 0,1 1000 10 100

Maintenance people Voice 30 3 1800 54 5400 2700

Station personnel Voice 30 2 4000 120 8000 4000

ETCS Data 500 4 800 400 3200 Ticket machines Data 1 0,1 1000 1 100

Train diagnostic Data 30 2 1000 30 2000

Shunting radio VGCS 600 4 250 150 1000

Broadcast-calls VBS 10 0,1 1000 10 100

Fixed subscribers Voice 30 3 800 24 2400 1200

Note: all values are assumptions

Special requirements on a GSM-R network

Figure 15 Call setup times defined by EIRENE

Call type Call setup time

Railway emergency call < 2s

Group calls between drivers in the same are < 5s

All operational mobile-to-fixed calls not covered by the above < 5s

All operational fixed-to-mobile calls not covered by the above < 7s

All operational mobile-to-mobile calls not covered by the above < 10 s

All low priority calls < 10 s

Figure 16 QoS requirements for ETCS (current proposal)

QoS Parameter Value for High Speed Lines

Connection establishment delay of mobile originated calls < 8.5s (95%), 10s (100%)

Connection establishment error ratio 7s(99%)

Network registration delay 30s (95%), 35s (99%), 40s (100%)



Typical GSM-R radio network structures

The typical GSM-R radio network consists of several elliptical cells alongside the tracks preferably with directional antennas in the track direction. Very often the use of composite cells is employed, i.e. directional antennas along the track but forming only one cell. This technique is preferably used on ETCS tracks where the reduction of the number of handovers is wanted.

Within railway stations, a higher amount of traffic is required (hot spots), whereas the speed requirements are reduced. Therefore large railway stations typically will have sectorized cells. Less populated areas with low speed tracks and bus connections just need an average voice connection. These cells may radiate as omni-directional cells (rural areas without ETCS).

To guarantee coverage, availability and access for the main railroads a special radio network with optimized

radio coverage for each cell has to be realized along their routes. Regional railroads and railway buses may use either public GSM or shall be included into the GSM-R network step by step to keep the investment at a reasonable level. Therefore frequency planning has to be carefully adjusted to allow both optimized coverage for long haul traffic as well as reduced coverage for regional railroads thus avoiding intercell interference. As a result of the criteria mentioned above, a typical GSM-R network architecture in both NSS and BSS uses redundancies as available from the existing GSM technology. In addition to this some further concepts will be realized as demonstrated below. The figures in this chapter show structures realized with the existing technology and common to public networks and a suggested structure for very high reliability.

Star connection: The BTS are connected to the BSC in a Star connection. This connection applies

especially to sectorized BTS with several carriers.

Chain connection: The BTS are connected to the BSC in a Chain connection via multidrop. Whenever a BTS fails or the link interface for the Abis-connection is defect, a relay switches the PCM30 through to the next BTS. The switchover will be seamless for the connection.

Star chain connection: The BTS are connected to the BSC in a Star Chain connection via multidrop. The first two BTS are connected in a chain, after the second BTS the connection is split up into a star chain. The advantage is a better usage of existing railway communication cables. Functionality in case of BTS or link failure is equal to the first prescribed connection types.

For the above described cases the critical path is always the cable connecting the BTSs. Since reliability of either copper wire, fiberoptic cable or microwave links in combination with the necessary

line termination (either NTPM, HDSL-modem or Drop in-Drop out-multiplexer) is not necessarily as high as the reliability of BTS and BSC, even a very high reliability of BTS will not improve availability of the system.

Therefore, railway applications with high requirements for reliability will make use of the multidrop loop architecture. Furthermore the interleaving of BTS of two different loops will decrease the consequences of a single BTS or BSC failure.

Loop Multidrop connection: The BTS are connected in a Loop Multidrop. If now the forward connection then fails, Nokia Siemens Networks BTS will switch seamlessly to the backward connection. This means that ongoing calls will not be dropped by loss of one transmission link.

In the described case, the risk of cable failure at the critical path is reduced. The operator may now choose either to connect two dedicated cables even separated by the cable duct (safe solution) or using logical connections on a fiberoptic PDH/SDH ring (economical solution).

Two interleaved BSCs with Loop Multidrop: The BTS are connected to two different BSC in Loop Multidrop interleaving with each other on a one-by-one scheme.

In the prescribed case, both the risk of a cable failure and a BTS or BSC failure is reduced. With adequate network planning these interleaving cells may be either planned as an overlay/underlay network using Nokia Siemens Networks proven feature Hierarchical Cell Structure (HCS) or just as neighboring cells. To receive an even higher reliability without a single point of failure within the GSM-R the following architecture is suggested:

The case shown above operates with a fully duplicated network structure with either collocated or staggered radio cells. To allow these two network levels several functions like:

Priority of cell A1 or B1 Other hierarchical cell parameters Subscriber administration Load distribution

will need to be agreed upon with the customer/operator.

Figure 21 Fully duplicated network structure with over-layered radio cells

MSC A

MSC B

BSS B

BSS A

Cell A1 - A4

Cell B1 - B4

Figure 18 Directional, sectorized and omni-directional cells

Figure 19 GSM-R architecture for low speed tracks and rural areas

Figure 20 GSM-R architecture for ETCS-lines (low and high redundant)

MSC

BSS

Chain connection

Star Chain connection

Star connection

BSS

MSC BSS

BSS

BSSLoop Multidrop connection

Two interleaved BSCs with Loop Multidrop connection



Radio Coverage

Radio network planning mainly depends on geographical and morphological data. Thus a basic coverage may always be calculated with existing models using digital maps of the respective area. These models need to be tuned for railway environment and to achieve a high location probability.

A typical plot for railway coverage made with Nokia Siemens Networks radio network planning tool can be seen below. The dark area shows a level of -85 dBm (train coverage) but even the brighter neighboring areas are sufficient for normal handheld supply.

Special care has to be taken regarding uncovered spots and interference (co-channel or adjacent channel). Uncovered spots may be supplied either with optimized locations for BTS and/or antennas. Where this does not solve the problem, additional repeaters may be used. Generally, the following are the minimum required planning data for radio network planning:

Minimum received level of 90 dBm for 95% location/time probability at 100m (ETCS 97%, Shunting 99 %) or even more to cope with ETCS requirementsMobile station output power 2W (33 dBm) or 8W (39 dBm)Mobile station RX sensitivity 102 dBmC/IC 20 dB co-channel interferenceC/IA 5 dB adjacent channel interferenceAntenna gain (typically 12 to 17 dB) and height above groundLosses in feeder cable and other components

Fading margin (slow, fast) Generally the network will be designed for Uplink/Downlink balance.

Network planning and design can be carried out by Nokia Siemens Networks network planning department to the extent required by the customer.

A link budget calculation is needed in order to ensure that a minimum signal level is available given the receiver sensitivity. The link budget calculation is on a per TRX basis and takes all system gains and losses into account, with established transmitter output power and maximum receiver sensitivity.

The usage of two different mobile types in GSM-R ( MS class 2 & MS class 5) with different output powers makes is impossible to determine a balanced link budget (up link and down link) for both mobile types. Therefore a certain compromise between class 2 and class 5 mobiles is necessary.

Numbering Plan requirements

The Number plan describes the system according to EIRENE specifications, and special adaptations made to the specific GSM-R system. It contains short numbers (speed dial), user groups (functional groups) used for Group calls and Broadcast, service and shift groups, traffic controllers, and a list of train numbers currently used.

In most cases the GSM-R numbering plan is integrated in the national numbering plan and the GSM-R operator has to apply for an own Network Destination Code, NDC.

Use if National EIRENE Numbers

The GSM-R numbering plan shall follow the EIRENE standard and consist of the following three distinct parts

1) Call Type:The Call Type (CT) prefix is used to distinguish between the different types of User Numbers that are allowed within the national EIRENE numbering plan. It is an indication to the network of how to interpret the number dialled.

2) User Identifier Number:The User Identifier Number (UIN) shall be one of the following numbers (as identified by the CT)

Running Number (RN): a number given to a train by operational staff for a particular journey. This

number shall be unique for the destination of the journey, and all RNs shall be the same length within a single GSM-R networkEngine Number (EN): a unique number given to a tractive unit to identify it permanently. The UIC has introduced a uniform identification marking system for a tractive stock crossing frontiers [UIC 438-3]. In order to call a particular locomotive, it shall be possible to call a number associated with the tractive units stock number. The total identification number consists of 11 digits. The actual number of the unit is denoted by six digits, which shall be used as the EN. In order to prevent duplication of numbering, as each railway is free to allocate the engine number leading to number uniqueness per country only, the Owning or registering Railway code should be added as the first digits.Coach Number (CN): a unique number given to each coach (which is not a tractive unit) to identify it permanently. The UIC has introduced a uniform identification marking system for passenger rolling stock [UIC

438-1]. In order to call a particular coach it shall be possible to call a number associated with the vehicle marking. The total vehicle marking consists of 12 digits. The actual number of the coach is denoted by seven digits (position 5 to 11 of the complete vehicle marking), which shall be used as the CN. In order to prevent duplication of numbering, as each railway is free to allocate the coach number leading to number uniqueness per country only, the Owning or registering Railway code should be added as the first digits.Shunting Team Location Number (STLN)Maintenance Team Location Number (MTLN)Train Controller Location Number (TCLN)Group Location Number (GLN) Mobile Subscriber Number (MSN)

3) Function Code:The Function Code (FC) is used as an identification of, for example, the person or equipment on a particular train, or a particular team within a given area.

CT UIN FC

CT Call TypeUIN User Identifier NumberFC Function Code

Figure 22 Typical radio network planning plots



GSM has been growing with rapid pace over the last few years. Over 80% of the worlds population is covered by mobile networks and growth continues unabated.

The GSM 900, 1800 and 1900 networks will most probably remain highly competitive over the next few decades. This will guarantee both investments in R&D of suppliers, increasing system performance and functionality as well as ongoing support of the GSM standard in the short as well as in the long run.

GSM-R networks will of course benefit from evolution forces driven by the huge Public GSM market. This chapter will concentrate on those particular fields where the evolution of GSM is already specified and, as we believe, of particular interest for the railways keeping in mind that many other improvements will also become applicable.

Evolution of GSM data services

In Public GSM networks, GSM has an up to date a voice centric system (the SMS messages are sent on a signalling channel, not a traffic channel). Data capabilities of GSM have not been widely used despite their advanced data transfer rates. Two major reasons could be identified:

Data rates of GSM bearer services are too low (9.6 kbps max.).Applications and terminals were not available in time with introduction of the services into the networks.

Today the situation is rapidly changing. Mobile Internet

access and telematic services are increasingly used for a wide range of public applications - car identification, cargo information and other services which make use of GSM data services.

Two major demands can be clearly identified on the market. On the one hand, higher bandwidth is required. On the other hand, many applications like telematic services or many railway applications have low data rates and typically high-burst transmissions and thus higher data rates are also required.

Starting with 14.4 kbps data rates will be increased with circuit switched data technology. High Speed Circuit Switched Data (HSCSD) will use channel aggregation to allow high data throughput. Starting from 28.8 kbps, ISDN like rates of 64 kbps are technically possible with HSCSD. However, HSCSD as a circuit switched service needs two traffic channels (TCH) as a minimum per connection. Therefore we recognize HSCSD as being the best choice for applications with strict real time constraints and bulk data transfer.A technological breakthrough in GSM was the introduction of General Packet Radio Services (GRPS). With the implementation of GPRS GSM-R networks will be extended for packet mode transmission and direct interworking with IP networks. GPRS network elements are built in addition to the existing network infrastructure. GPRS will support both burst and bulk data transfer with the advantage that the ultimate network resource of traffic channels (frequencies) may be used economically. Since GPRS represents a unique opportunity to enhance GSM-R, a more detailed chapter will

describe the major advantages and possible constraints of GPRS in a railway environment. Currently work is ongoing to investigate if it is possible to run ETCS over GPRS in order to save bandwidth.

GPRS in a railway environment

Several GSM-R networks have implemented GPRS for various applications. During 2002 we provided the first GSM-R network with GPRS in Sweden.

One of the main issues of GSM-R is spectrum efficiency. Economic use of frequencies is of special importance for the railway communication operator as the UIC frequency band is limited to 4 MHz (19 TDMA channels or, in circuit switched mode, 150 traffic channels).

GPRS as a packet data service restricts the usage of a traffic channel to the time the data packet is actually transmitted. Several (up to eight) users can simultaneously access one Packet Data Traffic Channel (PDTCH). This makes GPRS exceptionally well suited for any application requiring high-burst data transfer on a low data rate and saves traffic channels for other applications.

For transmission of bulk data, GPRS can offer a throughput of up to 120 kbps using advanced reservation and channel coding system with all eight timeslots available for one frequency (TRX). This throughput is then to be shared among all GPRS users present in the cell at that point of time. Furthermore, this data throughput is affected by the cell to interference ratio (C/I) available in the radio call.

Supposed railway applications with GPRS

All railway applications based on data transfer could be supported by GSM-R as there are available:

file transfers email systems mobile railway intranets mobile offices information broadcasts vehicle or cargo tracking applicationspassenger services like on-line booking/reservationETCS

ERTMS/ETCS level 2/3 currently require circuit switched data connections with a transfer delay of below 450 ms and extremely low bit error rates. The safety critical connection is established via HDLC protocol end-to-end between the ATP computer in the train and the RBC. Today there are investigations ongoing in order to verify if GPRS can be used as data bearer for ETCS. Taking this into account, GPRS should be validated in a loaded environment which could be a track equipped with ERTMS/ETCS to guarantee that the load situation is the one of a real railway network. On the other hand, industrial partners for ERTMS/ETCS need to define a packet data interface with security protocol. Therefore we believe that usage of GPRS for ERTMS/ETCS level 2/3 will be the long-term solution, but the standardisation effort is not to be forgotten and this can take a long time.

However, the biggest benefit is the possibility of a duplicated connection without wasting too many radio resources.

EDGE is implemented as a bolt-on enhancement for GSM and GPRS networks, making it easier for

existing GSM carriers to upgrade to it. EDGE is a superset to GPRS and can function on any network with GPRS deployed on it, provided the carrier implements the necessary upgrade.

Although EDGE requires no hardware or software changes to be made in GSM core networks, base stations must be modified. EDGE compatible transceiver units must be installed and the base station subsystem (BSS) needs to be upgraded to support EDGE. New mobile terminal hardware and software is also required to decode/encode the new modulation and coding schemes and carry the higher user data rates to implement new services.

Evolution to UMTSMobile communications systems started about 30 years ago as analogue systems with limited network capabilities. These and even the analogue cellular networks in the 450 MHz and 900 MHz range are considered as first-generation technology.

Systems like GSM are to be considered as second-generation technology. Network structure is still cellular but the connectivity and the services are equal to ISDN on the fixed network side. GSM-R benefits from this advantages and even though this system is in the commercial market it is still in progress due to additional specification and development.

The new, third-generation technology called UMTS (Universal Mobile Telecommunication System) adds bandwidth on demand to mobile communication systems. This is necessary since there is

clear evidence that mobile data applications are a fast growing market. With UMTS, true multimedia applications with very high data throughput in real-time mode becomes possible. In contradiction, GPRS with GSM, which opens the market for high data rate applications, will never have a comparable throughput.

Today there is no real evidence that UMTS could be of interest for the railways in the near future. Applications specified by EIRENE and other applications foreseeable need feature functionalities as specified in GSM Phase 2 and Phase 2+. GPRS will be a welcome extension to GSM-R networks due to the fact that high burst data transfer will out-rule bulk data transfer in railway networks by far. In addition, the railway community will have to apply once more for a frequency spectrum.

The existing GSM-R networks will most probably offer connectivity to UMTS and feature sets will be balanced, we believe that GSM-R will benefit from UMTS features. If railways really think about UMTS, it will be mainly in the field of Passenger Services such as allowing multimedia application on train. UMTS therefore may be introduced to GSM-R as an extension either by reuse of GSM-R infrastructure or in just connecting public UMTS networks to the GSM-R network, whenever required.

GSM-R Evolution



The need to modernize their communication networks is evident to many railway organisations. New communication technologies should not only give advantages regarding cost and operation & maintenance organisation, but also allow international interoperability and communication. New applications should make railway operation more attractive for both staff and passengers.

With GSM-R, European railways have definitely made the right choice. Based on ISDN, GSM is offering a wide range of services and internationally compatible features.

The success and penetration of GSM networks throughout the world show that it is the worlds most widely deployed digital wireless communication system, secure and proven in operation. In analogy to that GSM-R will tend to be the

leading mobile telephone system for the present and the near future.

The vision of UIC was to select a system for the railways that had several potential suppliers, was far spread in the world and needed as few modifications as possible. This vision is now a fact. The basic functionality of GSM-R is already implemented and has been delivered, tested and validated in the MORANE trials and in several GSM-R projects for use in railway networks. About 30 European railways have committed themselves to introducing this technology on their international network. The advantages of GSM-R will convince them that GSM-R is the right system for their complete networks.

Nokia Siemens Networks has many years of experience in commercial GSM-R projects. Thereby the development, implementation and improvement of standardized and

non-standardized GSM-R features has been conducted and proved. Also we take a major part in the validation process for GSM-R. Gaining from these activities Nokia Siemens Networks is one step ahead on the path for GSM-R introduction. The fully specified EIRENE functionality is already verified, tested and in use in several GSM-R networks.

Regarding this and the progress GSM has made since 1991 in comparison to concurring technologies GSM-R is definitely the right choice of UIC for ETCS and other railway communication systems and Nokia Siemens Networks is the right partner to realize this.

ABC Administration and Billing Centre

AC Authentication CentreASCI Advanced Speech Call

ItemsATC Automatic Train ControlATP Automatic Train

ProtectionAuC Authentication CentreBHCA Busy Hour Call AttemptBR British RailBS Base StationBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationCBS Cell Broadcast Service CCITT Committee for

International Telegraph & Telecommunications

CI Cell IdentifierCLIP Calling Line Identification

PresentationCLIR Calling Line Identification

RestrictionCOLP COnnected Line

identification PresentationCOLR COnnected Line

identification RestrictionCT Craft TerminalC/I Carrier to Interference

ratioDECT Digital Enhanced

Cordless Telecommunication

E.164 CCITT Recommendation (Numbering plan for the ISDN era)

EDSS European Digital Subscriber Signalling System

EIR Equipment Identification Register

EIRENE European Integrated Railway radio Enhanced NEtwork

eMLPP Enhanced Multi-Level Precedence and Pre-emption service

ERTMS European Rail Traffic Management System

ETCS European Train Control System

ETSI European Telecommunications Standards Institute

EWSD Elektronisches Whlsystem Digital (Digital Switching System)

FN Functional NumberGCR Group Call RegisterGMSC Gateway Mobile

Switching CentreGPRS General Packet Radio

Services GPS Global Positioning

SystemGSM Global System for Mobile

CommunicationGSM-R Global System for Mobile

Communication (for Railway applications)

HDLC High Level Data Link Control protocol

HDSL High speed Digital Subscriber Line

HPLMN Home Public Land Mobile Network

HLR/AC Home Location Register/Authentication Centre

HSCSD High Speed Circuit Switched Data

HW HardwareID IdentificationIN Intelligent NetworkIP Internet ProtocolISDN Integrated Services

Digital NetworkLAC Local Area CodeLAN Local Area NetworkLZB LinienZugBeeinflussungMAC Message Authentication

CodeMCC Mobile Country CodeMLPP Multi-Level Precedence

and Pre-emption serviceMNC Mobile Network CodeMOC Mobile Originated CallMORANE MObile RAdio for

Railways Networks in Europe

MoU Memorandum of Understanding

MS Mobile SubscriberMSC Mobile Switching CentreMSC/VLR Mobile Switching Centre/

Visitor Location RegisterMSISDN Mobile Station ISDN

NumberMTC Mobile Terminated CallNTPM Network Termination

Point ModuleNSS Switching SubSystemPABX Private Automatic Branch

eXchangePAMR Public Access Mobile

RadioPCM Pulse Code Modulation

PCS Personal Communications System

PDH Plesiochronous Digital Hierarchy

PDTCH Packed Data Traffic Channel

PLMN Public Land Mobile Network

PMR Private Mobile RadioPSTN Public Switched

Telephone NetworkQoS Quality of ServicesRAC Railway Access CodeRBC Radio Block CentreRFI Request For InformationRFQ Request For QuotationSACCH Stand-Alone Control

CHannelSCI Subscriber Controller

InputSCP Service Control PointSDH Synchronous Digital

HierarchySIB Service Independent

building BlocksSMG Special Mobile GroupSMP Service Management

PointSMS Short Message ServiceSSP Service Switching PointSW SoftwareTCH Traffic ChannelTDMA Time Division Multiple

AccessTETRA TrunkedTK Telecommunication TRAU Transcoding Rate

Adaptation UnitTRX TransceiverUIC Union International de

Chemin de ferUIN User Identifier NumberUMTS Universal Mobile

Telephone SystemUSSD Unstructured

Supplementary Service Data

UUS.1 User to User Signalling 1VBS Voice Broadcast ServiceVGCS Voice Group Call ServiceVLR Visitor Location RegisterVMS Voice Mail ServiceVMSC Visited MSCWLAN Wireless Local Area

Network

Conclusion List of abbreviations


gsm r description

Documents

en nokia siemens networks

introduction gsmr

pm228 gsmr

status of gsm

industry champions nokia

public gsm systems

customers key challenges

lead industry change