ETSI TR 103 442 V1.2.1 (2016-09)

ETSI TR 103 442 V1.2.1 (2016-09)






TECHNICAL REPORT
Railways Telecommunications (RT);
Shared use of spectrum between
Communication Based Train Control (CBTC)
and ITS applications

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2 ETSI TR 103 442 V1.2.1 (2016-09)



Reference
RTR/RT-JTFIR-45
Keywords
ITS, railways
ETSI
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3 ETSI TR 103 442 V1.2.1 (2016-09)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Executive Summary . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 8
4 CBTC description . 9
5 Market information. 9
6 CBTC Technical information . 9
6.1 CBTC Communication needs . 9
6.2 Simultaneous CBTC communications in a given geographical area . 11
6.3 Propagation parameters of CBTC radio communication . 12
6.3.1 General CBTC radio properties . 12
6.3.2 Propagation in tunnel . 12
6.3.3 Propagation Outdoors . 12
6.3.3.1 On line . 12
6.3.3.2 In depot or stabling area . 12
6.4 Mandatory characteristics to ensure CBTC safety . 12
6.5 Mandatory characteristics derived from the CBTC availability needs . 13
6.6 Summary of CBTC communication requirements . 14
6.7 CBTC typical line description . 14
6.7.1 In tunnel . 14
6.7.2 Outside . 14
7 ITS Technical information . 15
7.1 ITS description . 15
7.2 Intelligent Transport System communication architecture . 16
7.3 Networking and transport . 16
7.4 Access . 16
7.5 Security . 16
7.6 Decentralized Congestion Control . 17
7.7 CEN DSRC co-existence mitigation . 17
8 Sharing Issue . 18
8.1 Sharing scenarios . 18
8.2 Technical Sharing Solution . 18
8.2.1 Different sharing proposals . 18
8.2.2 Mitigation methods . 19
8.2.2.1 Changing the transmit parameters . 19
8.2.2.2 Harmonized access layer protocol . 19
8.2.3 Methods to detect a mitigation area . 20
8.2.3.1 Geographic database . 20
8.2.3.2 Detection of the CBTC signal . 20
8.2.3.3 CBTC warning beacon . 20
8.3 Security concern . 21
8.4 Sharing conditions . 21
8.4.1 ITS Conditions . 21
ETSI

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4 ETSI TR 103 442 V1.2.1 (2016-09)
8.4.2 CBTC Conditions . 21
9 Conclusion . 22
Annex A: Case Study of Brussels Metro . 25
A.1 General . 25
A.2 Conclusion . 27
History . 28


ETSI

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5 ETSI TR 103 442 V1.2.1 (2016-09)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Railway Telecommunications (RT).
Modal verbs terminology
In the present document "should", "should not", "may", "need not", "will", "will not", "can" and "cannot" are to be
interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Executive Summary
The present document summarizes the possible solution for a shared deployment of the CBTC systems for urban rail
systems and cooperative ITS systems based on ETSI ITS-G5 in the band 5 855 MHz to 5 925 MHz.
In the band 5 905 MHz to 5 925 MHz all sharing proposals assume that CBTC urban rail safety related applications will
have a prioritization over the C-ITS applications. In the band 5 875 MHz to 5 905 MHz C-ITS will have the priority. In
the band 5 855 MHz to 5 875 MHz both systems are treated equally.
Different sharing mechanisms are proposed in the present document:
• Implementation of mitigation techniques on the ITS side like detect and avoid or geolocation based solution
using 5 MHz CBTC systems.
• Deployment of the ETSI ITS access mechanisms in the CBTC system with 10 MHz channelization.
• Fully integration of CBTC as part of the 10 MHz based ETSI ITS systems with prioritization mechanisms in
all protocol layers based on the existing Decentralized Congestion Control mechanism of the ETSI ITS
system.
Introduction
The present document has been developed in cooperation with TC ITS in order to present to the Electronic
Communications Committee (ECC) of the European Conference of Post and Telecommunications Administrations
(CEPT) a common point of view regarding sharing possibilities between CBTC and ITS applications in the 5 875 MHz
to 5 925 MHz frequency band.
After having clearly defined CBTC applications, the present document defines first the functional needs of CBTC
regarding its communication. From that, technical needs for the communication system are derived, and the scenarios
where sharing the spectrum between CBTC application and ITS road applications could be an issue are described.
Finally the different technical means of sharing bandwidth are introduced and the next steps including a proposal for

short term regulation are defined.
ETSI

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6 ETSI TR 103 442 V1.2.1 (2016-09)
1 Scope
The present document investigates the possibility of shared use of spectrum between CBTC and ITS applications in the
5 875 MHz to 5 925 MHz under the assumption that CBTC applications have priority over ITS-G5 applications.
2 References
2.1 Normative references
Normative references are not applicable in the present document.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ECC/DEC/(08)01: "ECC Decision (08)01 of 14 March 2008 on the harmonised use of the
5875-5925 MHz frequency band for ITS, and subsequent amendments".
[i.2] ETSI TR 103 111 (V1.1.1): "Electromagnetic compatibility and Radio spectrum Matters (ERM);
System Reference document (SRdoc); Spectrum requirements for Urban Rail Systems in the
5,9 GHz range".
[i.3] CENELEC EN 50159: "Railway applications - Communication, signalling and processing systems
- Safety-related communication in transmission systems".
[i.4] ETSI EN 302 665 (V1.1.1): "Intelligent Transport Systems (ITS); Communications Architecture".
[i.5] ETSI TR 101 607 (V1.1.1): "Intelligent Transport Systems (ITS); Cooperative ITS (C-ITS);
Release 1".
[i.6] ETSI TR 102 638: "Intelligent Transport Systems (ITS); Vehicular Communications; Basic Set of
Applications; Definitions".
[i.7] ETSI TS 101 556-1 (V1.1.1): "Intelligent Transport Systems (ITS); Infrastructure to Vehicle
Communication; Electric Vehicle Charging Spot Notification Specification".
[i.8] ETSI EN 302 637-2 (V1.3.2): "Intelligent Transport Systems (ITS); Vehicular Communications;
Basic Set of Applications; Part 2: Specification of Cooperative Awareness Basic Service".
[i.9] ETSI EN 302 637-3 (V1.2.2): "Intelligent Transport Systems (ITS); Vehicular Communications;
Basic Set of Applications; Part 3: Specifications of Decentralized Environmental Notification
Basic Service".
[i.10] ETSI TS 103 301 (V1.1.1): "Intelligent Transport Systems (ITS); Vehicular Communications;
Basic Set of Applications; Facilities layer protocols and communication requirements for
infrastructure services".
[i.11] ETSI TS 102 687 (V1.1.1): "Intelligent Transport Systems (ITS); Decentralized Congestion
Control Mechanisms for Intelligent Transport Systems operating in the 5 GHz range; Access layer
part".
ETSI

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7 ETSI TR 103 442 V1.2.1 (2016-09)
[i.12] ETSI TR 101 612 (V1.1.1): "Intelligent Transport Systems (ITS); Cross Layer DCC Management
Entity for operation in the ITS G5A and ITS G5B medium; Report on Cross layer DCC algorithms
and performance evaluation".
[i.13] ETSI TS 103 175 (V1.1.1): "Intelligent Transport Systems (ITS); Cross Layer DCC Management
Entity for operation in the ITS G5A and ITS G5B medium".
[i.14] ETSI TS 102 792 (V1.2.1): "Intelligent Transport Systems (ITS); Mitigation techniques to avoid
interference between European CEN Dedicated Short Range Communication (CEN DSRC)
equipment and Intelligent Transport Systems (ITS) operating in the 5 GHz frequency range".
[i.15] ETSI EN 302 571: "Intelligent Transport Systems (ITS); Radiocommunications equipment
operating in the 5 855 MHz to 5 925 MHz frequency band; Harmonised Standard covering the
essential requirements of article 3.2 of Directive 2014/53/EU".
[i.16] ETSI EN 302 663: "Intelligent Transport Systems (ITS); Access layer specification for Intelligent
Transport Systems operating in the 5 GHz frequency band".
TM
[i.17] IEEE 802.11 : "IEEE Standard for Information technology--Telecommunications and
information exchange between systems Local and metropolitan area networks--Specific
requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications".
[i.18] Standardisation mandate addressed to cen, cenelec and etsi in the field of information and
communication technologies to support the interoperability of co-operative systems for intelligent
transport in the european community (M/453 EN).
NOTE: Available at http://www.etsi.org/about/our-role-in-europe/public-policy/ec-mandates.
[i.19] ETSI TS 103 097: "Intelligent Transport Systems (ITS); Security; Security header and certificate
formats".
[i.20] CEPT/ERC Recommendation 70-03: "Relating to the Use of Short Range Devices (SRD)",
Tromso 1997, Subsequent amendments 07 February 2014".
[i.21] Commission Decision 2008/671/EC of 5 August 2008 on the harmonised use of radio spectrum in
the 5875-5905 MHz frequency band for safety-related applications of Intelligent Transport
Systems (ITS).
[i.22] ECC/REC/(08)01: "Use of the band 5855-5875 MHz for Intelligent Transport Systems (ITS)".
[i.23] Commission Implementing Decision 2013/752/EU of 11 December 2013 amending Decision
2006/771 on harmonisation of the radio spectrum for use by short-range devices and repealing
Decision 2005/928/EC.
TM
[i.24] IEEE 1474.1 -2004: "IEEE Standard for Communications-Based Train Control (CBTC)
Performance and Functional Requirements".
[i.25] Brussels Regional Authority - Institut Bruxellois de Statistique et d'Analyse (IBSA).
ETSI

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8 ETSI TR 103 442 V1.2.1 (2016-09)
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
data communication system: global communication architecture into which radio communication links are integrated
ITS station: communication equipment implementing an ITS protocol stack according to the ETSI ITS communication
architecture
NOTE: Within the present document, this term is more specifically used for on-board units and roadside units
transmitting in the ITS-G5 frequency band.
ITS-G5A: frequency band from 5 875 MHz to 5 905 MHz
ITS-G5B: frequency band from 5 855 MHz to 5 875 MHz
safety: freedom from unacceptable levels of risks resulting from unintentional acts or circumstances
security: freedom from unacceptable levels of risks resulting from intentional acts or circumstances
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AP Access Point
ASIL Automotive Safety Integrity Level
ASIL-A Automotive Safety Integrity Level
ATC Automatic Train Control
ATO Automatic Train Operation
ATP Automatic Train Protection
ATS Automatic Train Supervision
C2C-CC Car to Car Communication Consortium
CAM Cooperative Aware Message
CBTC Communication Based Train Control
CEPT European Conference of Postal and Telecommunications Administrations
C-ITS Cooperative Intelligent Transportation System
DCC Decentralised Congestion Control
DCS Data Communication System
DEC DECision
DENM DEN Message
DSRC Dedicated Short Range Communication
EC European Community
ECC Electronic Communications Committee
EDCA Enhanced Distributed Channel Access
EIRP Equivalent Isotropically Radiated Power
EM Electro Magnetic
GN GeoNetworking
HW HardWare
IEEE Institution of Electrical and Electronic Engineers
IP Internet Protocol
ITS Intelligent Transportation System
ITS-G 5,9 GHz Cooperative ITS system
ITS-S Intelligent Transportation System Station
LOS Line Of Sight
MAC Medium ACcess
MIMO Multiple Input Multiple Output
NLOS Non Line Of Sight
OEM Original Equipment Manufacturer
ETSI

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9 ETSI TR 103 442 V1.2.1 (2016-09)
OFDM Orthogonal Frequency Division Multiplexing
OSI Open Systems Interconnection
QPSK Quadrature Phase Shift Keying
REC RECommendation
SIL Safety Integrity Level
SNR Signal to Noise Ratio
SW SoftWare
TAC Transmit Access Control
TTT Transport and Traffic Telematics
V2I Vehicle to Infrastructure
V2V Vehicle to Vehicle
VRU Vulnerable Road User
4 CBTC description
The primary public objective of this system is to provide urban rail and regional railway operators with a means to
control and manage the train traffic on their own networks. Metro lines which are operated at a high level of
performance and short intervals between successive trains are now installing Communications-Based Train Control
(CBTC) systems.
CBTC is a wireless Automatic Train Control (ATC) system, more flexible and cost efficient than traditional ATC.
CBTC systems are deployed on urban and suburban train on dedicated tracks. Tramways, tram trains and buses are not
covered by this system.
The standard IEEE 1474.1™ [i.24] gives the following definition:
A CBTC system is a continuous, automatic train control system utilizing:
• high-resolution train location determination, independent of track circuits;
• continuous, high-capacity, bidirectional train-to-wayside data communications;
• train borne and wayside processors capable of implementing automatic train protection (ATP) functions, as
well as optional automatic train operation (ATO) and automatic train supervision (ATS) functions.
CBTC application requirements are defined in the standard IEEE 1474.1™ [i.24].
CBTC systems allow running trains only 90 seconds apart with total safety for the passengers and the staff (or even less,
the headway depending upon time spent by the train at every station for passengers to leave and board trains, the
distance between stations and profile of the line as well as the possible acceleration, maximum speed and deceleration
of the train).
5 Market information
The automation of existing urban rail lines and the development of fully unattended metro operation (no staff on board)
are booming and represent tomorrow's challenges in this sector. Millions of passengers use urban public transport every
day (in Europe 31,6 million daily passengers in 48 cities only for metro), and the European Union's modal shift
objective means more people using public transport. CBTC markets have been presented in ETSI TR 103 111 [i.2].
6 CBTC Technical information
6.1 CBTC Communication needs
Although IEEE 1474.1™ [i.24] defines the CBTC system and its requirements, the system itself as a whole is not fully
standardized which means that some parts, and in particular its communication system, are implementation dependent.
ETSI

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10 ETSI TR 103 442 V1.2.1 (2016-09)
The MODURBAN project issued a functional requirement specification for CBTC systems, and a MODURBAN
architecture document (partially public), which allocates functions to a system or subsystem level but leaving some
open options and without fully specifying in details the interfaces.
As a consequence, the needs for communication and the definition of messages to be exchanged are not standardized,
even if some metro authorities promoted interoperability specifications which enable the construction of a complete
CBTC system by assembling subsystems from different manufacturers: one company can provide the wayside ATC
subsystem, while another one can provide the on-board ATC subsystem, a third one can provide the data
communication system, a fourth one can provide the ATS.
Achieving such compatibility of the subsystems require that an interoperability specification fully defines the interfaces,
which include, of course, an extensive definition of all the data exchanges through the radio channel: definition of the
protocols, list of the messages, size and detailed consist of each message in terms of functional data, performances
including rates of emission and reception for each communicating piece of equipment and each type of message.
Nevertheless these interoperability specifications, when they exist, are project dependant.
Finally, the level of performances (for example the headway between trains or the guaranteed reaction time of the
system to an unexpected safety hazard) highly influences the requirements allocated to the communication system: it
drives the amount of data to be transmitted, the frequency at which they need to be transmitted and the quality of the
transmission such as the frame error rate and the latency of the transmission.
Therefore it should be pointed out that all the data given below are based on principles and existing implementations
and are used as an example to justify the common needs for communication of CBTC, but cannot be seen as
characteristics fulfilled by all CBTC systems on the market.
CBTC communications can be classified in different groups based on their conditions for transmission, and also based
on their criticality regarding the system performance.
Some messages need to be transmitted and received regularly in order to ensure that on-board and wayside CBTC
subsystems are continuously up-to-date (typically while a train is moving and updating its location) and to ensure they
can 'monitor' each other for a safe evaluation of critical functions performed by the other interoperable subsystems.
Such messages are typically transmitted periodically and are therefore known as "periodic data". Different periods may
coexist at the same time on a same interface.
EXAMPLE: From the above-mentioned interoperable CBTC applications, some messages are transmitted at a
period of 200 ms while others are transmitted every 360 ms and some others at a period of a few
seconds.
The transmission requirement for periodical data generally gives the base for the calculation of the "mean" required
throughput for CBTC. The following periodic CBTC messages are transmitted from train to wayside:
• A 'Location Report' message sent by the on-board CBTC of each train to the wayside CBTC ('Zone
Controller'). These messages help the Zone Controller to continuously track the trains' position on a portion of
the metro line designated as its 'territory'. It should be noted that a train generally communicates with one Zone
Controller but it may also have to communicate with two Zones Controllers in order to handle smooth
transition from one territory to the next one at their common border. It may even have to anticipate
communications with 3 Zone Controllers in some specific configurations (for example when the track is
subdivided into two diverging branches).
The 'Location Report" message includes data such as the location of both ends of the train, its speed, the train
consist, etc.
If that message is received with a delay greater than 100 ms, then it is no longer useful and will be co
...