ETSI TR 103 459 V1.2.1 (2020-08)

Rail Telecommunications (RT); Future Rail Mobile Communication System (FRMCS); Study on system architecture

RTR/RT-0052

General Information

• Status: Not Published
• Technical Committee: RT - Railway telecommunications
• Current Stage: 12 - Completion
• Due Date: 17-Aug-2020
• Completion Date: 19-Aug-2020

Standards Content (Sample)

ETSI TR 103 459 V1.2.1 (2020-08)






TECHNICAL REPORT
Rail Telecommunications (RT);
Future Rail Mobile Communication System (FRMCS);
Study on system architecture

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2 ETSI TR 103 459 V1.2.1 (2020-08)



Reference
RTR/RT-0052
Keywords
architecture, FRMCS, railways
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3 ETSI TR 103 459 V1.2.1 (2020-08)
Contents
Intellectual Property Rights . 6
Foreword . 6
Modal verbs terminology . 6
Executive summary . 7
Introduction . 7
1 Scope . 8
2 References . 8
2.1 Normative references . 8
2.2 Informative references . 8
3 Definition of terms, symbols and abbreviations . 10
3.1 Terms . 10
3.2 Symbols . 11
3.3 Abbreviations . 11
3.4 Notion of logical architecture, technical realization and physical implementation . 13
4 High level description . 14
5 Analysis of architectural implications of key aspects to be covered by FRMCS . 15
5.1 General . 15
5.2 Analysis of architectural requirements from UIC TOBA . 15
5.3 Analysis of architectural requirements from 3GPP TR 22.889 . 16
5.4 Identification and addressing . 20
5.4.1 General . 20
5.4.2 Design assumptions . 21
5.4.3 Identification and addressing schemes . 21
5.4.3.1 General . 21
5.4.3.2 Identification and addressing in the application stratum . 22
5.4.3.3 Identification and addressing in the service stratum . 22
5.4.3.3.1 Introduction and definitions . 22
5.4.3.3.2 Relationship between identities in the IMS . 23
5.4.3.3.3 Basic MC service identities . 24
5.4.3.3.4 Alternative MC service identities . 24
5.4.3.3.5 Relationship identities . 25
5.4.3.4 Identification and addressing in the transport stratum. 25
5.4.4 Implications on the FRMCS system architecture. 25
5.5 System Security . 26
5.5.1 Introduction and requirements . 26
5.5.2 Expected security layers in the FRMCS system . 27
5.5.3 Required security functions . 28
5.5.4 Required interfacing with external systems . 29
5.5.5 Implications on the FRMCS system architecture. 30
5.6 Positioning . 30
5.6.1 Definitions . 30
5.6.2 General . 31
5.6.3 Position processing categories . 32
5.6.4 For further study . 32
5.7 Migration from GSM-R to FRMCS . 33
5.7.1 Introduction. 33
5.7.2 Onboard migration . 33
5.7.3 ETCS transport modes . 33
5.7.4 GSM-R/FRMCS communication service migration at deployment boundaries . 34
5.7.5 Implications on the FRMCS system architecture. 35
6 FRMCS logical architecture . 35
6.1 System boundaries and high-level logical architecture . 35
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4 ETSI TR 103 459 V1.2.1 (2020-08)
6.2 Description of main logical entities . 36
6.2.1 FRMCS Mobile Application Client and FRMCS Service Client . 36
6.2.1.1 Introduction . 36
6.2.1.2 FRMCS Mobile Application Client . 37
6.2.1.3 FRMCS Service Client . 38
6.2.2 FRMCS Mobile Gateway . 38
6.2.3 Mobile Radio . 38
6.2.4 Trackside Transport . 39
6.2.5 FRMCS Service Server . 39
6.3 Key reference points to be specified. 39
6.3.1 OB . 39
APP
6.3.2 OB . 40
RAD
6.3.3 TS . 40
FS
7 FRMCS deployment and border crossing scenarios . 40
7.1 General . 40
7.2 Scenario 1a: Multiple trackside access domains with a common core network . 41
7.3 Scenario 1b: Multiple trackside access domains under a common core network (infrastructure sharing) . 41
7.4 Scenario 2: Interconnected Trackside Transport domains with separate core networks . 42
7.5 Scenario 3: Isolated transport and service domains . 43
7.6 Scenario 4: Border-crossing scenarios . 44
7.6.1 General . 44
7.6.2 Scenario 4a: Border-crossing scenario (isolated application domains) . 45
7.6.3 Scenario 4b: Border-crossing scenario (shared application domain) . 47
7.6.4 Scenario 4c: Border-crossing scenario (shared application and service domain) . 49
8 Possible technical realization of the FRMCS system . 49
8.1 General . 49
8.2 Potential 3GPP building blocks and reference points mapped to FRMCS logical architecture . 49
8.3 Potential solutions for the support of multiple Mobile Radios and/or multiple Trackside Transport
domains . 52
8.3.1 Introduction. 52
8.3.2 Service-level solution based on the MC framework . 52
8.3.3 Transport-level solutions: Core-centric integration using ATSSS . 54
8.3.4 Transport-level solutions: Above-the-core using MAMS . 55
8.3.5 Transport-level solutions: Above-the-core using ATSSS-Emulated solution . 56
8.3.6 Comparison of the possible solutions . 57
8.3.7 Preliminary conclusion . 61
8.4 Potential physical implementation of onboard system . 61
8.5 Potential physical implementation of trackside system . 62
8.6 Potential technical realization of a handheld device . 62
9 Gap analysis . 63
9.1 Mapping of functional service requirements to standardized 3GPP functions . 63
9.2 Identified risks . 65
10 Topics for further study . 65
Annex A: Supportive Material on MC, 4G and 5G Support for Rail Communication . 66
A.1 Mission Critical service support for Rail Communication . 66
A.1.1 General . 66
A.1.2 Arguments for loose coupling of data centric Railway Applications . 66
A.1.3 Integration of data centric Railway Applications . 66
A.1.4 Conclusion . 67
A.2 FRMCS/4G support for Railway Applications . 67
A.2.1 General . 67
A.2.2 QoS Management in LTE . 68
A.3 FRMCS/5G support for Railway Applications . 68
A.3.1 General . 68
A.3.2 QoS Management in 5G/NR . 69
A.3.3 Comparison and Suitability of QoS Management Options for Rail Operations . 70
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5 ETSI TR 103 459 V1.2.1 (2020-08)
A.4 Possibility to realize FRMCS System with 4G core network . 70
Annex B: Change History . 72
History . 73


ETSI

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6 ETSI TR 103 459 V1.2.1 (2020-08)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables 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.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Railway Telecommunications (RT).
The contents of the present document are subject to continuing work within TC RT and may change following formal
TC RT approval. Should RT modify the contents of the present document, it will be re-released by the TC RT with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
0 presented to TC RT for information;
1 presented to TC RT for approval; or
2 greater indicates TC RT approved document under change control;
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.;
z the third digit is incremented when editorial only changes have been incorporated in the document.
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.
ETSI

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7 ETSI TR 103 459 V1.2.1 (2020-08)
Executive summary
Since the first studies on the successor to GSM-R have been launched by UIC in 2012, the railway community has been
considering how to meet railway requirements with a future proof and flexible radio communication system.
The rail needs are defined in the User Requirements Specification (URS) [i.1] and the Telecom Onboard Architecture
(TOBA) Requirements [i.2] delivered by the UIC Project Future Railway Mobile Communications System (FRMCS).
From the UIC requirements, requirements relevant to 3GPP have been captured in 3GPP TR 22.889 [i.3]. Altogether,
the stated requirements are the basis for the development of the GSM-R successor.
The present document is a study on FRMCS system architecture, which initially describes a potential logical FRMCS
architecture that is suitable to meet the rail requirements according to the requirement documents cited before, and the
key reference points that are to be specified. As one input to the design, it provides an analysis of specific challenges
such as security, migration, positioning, etc., and derives their implications on the FRMCS architecture. The present
document also describes several deployment scenarios (for instance related to setups with multiple transport networks
operated by different entities), which are also relevant to the design of the FRMCS system architecture, as this should
support all deployment scenarios that are currently envisioned. Beyond the description of the logical FRMCS
architecture, the present document then elaborates on possible technical realizations of the FRMCS architecture through
building blocks from 3GPP and from other standards bodies. Special emphasis is here put on consideration for the
support of multiple onboard/handheld radios and/or multiple trackside transport domains, and the support of border-
crossing scenarios. Finally, the present document provides a functional gap analysis and identifies risks, before listing
topics for further study.
Introduction
The Technical Committee Rail Telecommunications (TC RT) is the "home" for those telecommunication aspects of rail
transportation which are not part of the specification of the current mobile communication technologies themselves. TC
RT is in particular responsible for the development and maintenance of GSM-R standards.
GSM-R has been a great success not only in Europe, where more than 100 000 km of railway tracks are daily operated
through GSM-R, but also worldwide, and this number will double within the next years due to the on-going installations
of this technology all over the world.
As the needs of the railways are constantly evolving, in particular in the context of the digitalisation of rail operation
that is pursued in many countries, and considering the upcoming obsolescence of GSM-R technology, UIC launched in
2012 the first studies for a successor to GSM-R, pertinently named Future Railway Mobile Communication System
(FRMCS). The UIC project then concretely delivered the new User Requirements Specifications (URS) [i.1] focusing
mainly on rail communication needs - as a basis for the development of the GSM-R successor.
The present document is a study on the FRMCS system architecture, which defines a logical FRMCS architecture and
likely deployment scenarios, and which elaborates in detail on possible technical realizations of the FRMCS system.
The result of this study is expected to provide the basis for the subsequently following normative work on FRMCS in
ETSI.

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8 ETSI TR 103 459 V1.2.1 (2020-08)
1 Scope
The present document is a technical report, in line with the scope and field of application of its related Work Item. In
particular, it covers:
• Definition of key terms and a high-level description of the FRMCS architecture, as agreed among UIC and ETSI
(see clauses 3 and 4, respectively).
• An analysis of the architectural implications of various requirements on the FRMCS system captured in UIC
TOBA and 3GPP TR 22.889 [i.3], and of aspects such as identification and addressing, security, positioning and
migration (see clause 5).
• A description of the logical architecture of the FRMCS system, including a description of the main logical
entities and key reference points among these (see clause 6).
• A derivation of key deployment and border-crossing scenarios that the FRMCS architecture should support (see
clause 7).
• An investigation of possible technical realizations of the FRMCS system, based on the usage of building blocks
from 3GPP and other standards bodies (see clause 8).
• A gap analysis and identification of risks related to the FRMCS standardization, for instance due to its
dependency on timelines of different standards bodies (see clause 9).
Finally, the present document identifies the next steps to ensure the complete definition of the FRMCS system.
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] UIC FRMCS URS v5.0: "User Requirements Specification".
[i.2] UIC FRMCS TOBA-7510 (V1.0.0) (April 2020): "FRMCS Telecom On-Board System -
Functional Requirements Specification".
[i.3] 3GPP TR 22.889 (V17.2.0) (January 2020): "Study on Future Railway Mobile Communication
System (FRMCS)".
[i.4] 3GPP TS 21.905 (V16.0.0) (June 2019): "Vocabulary for 3GPP Specifications".
[i.5] 3GPP TS 23.501 (V16.4.0) (March 2020): "System architecture for the 5G System (5GS)
(Release 16)".
[i.6] 3GPP TS 24.501 (V16.4.1) (April 2020): "Non-Access-Stratum (NAS) protocol for 5G System
(5GS); Stage 3 (Release 16)".
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9 ETSI TR 103 459 V1.2.1 (2020-08)
[i.7] 3GPP TS 22.280 (V17.2.0) (December 2019): "Mission Critical Services Common Requirements
(MCCoRe); Stage 1".
[i.8] 3GPP TR 28.801 (V15.1.0) (January 2018): "Telecommunication management; Study on
management and orchestration of network slicing for next generation network".
[i.9] 3GPP TS 23.228 (V16.4.0) (March 2020): "IP Multimedia Subsystem (IMS); Stage 2".
[i.10] 3GPP TS 23.003 (V16.2.0) (March 2020): "Numbering, addressing and identification".
[i.11] 3GPP TS 23.280 (V17.2.0) (March 2020): "Common functional architecture to support mission
critical services; Stage 2".
[i.12] UIC FRMCS TOBA-7540 (V1.0.0) (April 2020): "FRMCS Telecom On-Board System -
Architecture Migration Scenarios".
[i.13] 3GPP TR 23.796 (V16.0.0) (March 2019): "Study on application architecture for the Future
Railway Mobile Communication System (FRMCS) Phase 2".
[i.14] 3GPP TS 27.007 (V16.4.0) (March 2020): "AT command set for User Equipment (UE)".
[i.15] ETSI TS 123 002 (V15.0.0): "Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS); LTE; Network architecture (3GPP
TS 23.002 version 15.0.0 Release 15)".
[i.16] 3GPP TS 24.193 (V1.2.0) (May 2020): "
...