Tuesday, 7 September 2021

Future Railway Mobile Communication System (FRMCS)


I have been meaning to write on this topic for a very long time. The discussion started back in 2016 when the limitations of GSM-R were obvious and it was recognised that a successor will be needed sooner or later. The International Railway Union (UIC) published a user requirement specification in their paper “Future Railway Mobile Communication System - FRMCS”. This is available on 3GPP server as liaison statement S1-161250.

As 3GPP notes in their article, this was the trigger for them to go ahead and start the studies. Then in Release 16, 3GPP TS 22.289 "Mobile communication system for railways" outlined the requirements for railway communication, beyond the 3GPP Future Railway Mobile Communication System (FRMCS) Phase 1 specs. Details are available on this post here.

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The latest version of 3GPP TR 22.889, Study on Future Railway Mobile Communication System; Stage 1 is from Release 17. The introduction to the document clarifies:

The railway community is considering a successor communication system to GSM-R, as the forecasted obsolescence of the 2G-based GSM-R technology is envisaged around 2030, with first FRMCS trial implementations expected to start around 2020. 

The Future Railway Mobile Communication System (FRMCS) Functional Working Group (FWG) of the International Union of Railways (UIC) have investigated and summarised their requirements for the next generation railway communication system in the Future Railway Mobile Communication User Requirements Specification (FRMCS URS). The present document is based on this input given by the UIC/ETSI TC-RT 

Study on FRMCS Evolution (FS_eFRMCS), available as SP-201038 clarifies:

The UIC FRMCS programme was recently releasing stable version 5.0.0 of the User Requirement Specification, version 2.0.0 of the Functional Use Cases and a new specification item, version 1.0.0 of the Telecom On-Board System - Functional Requirements Specification, as a further step in the evolution of the FRMCS specifications. The UIC FRMCS Programme is developing all the technical conditions for the 5G FRMCS, with the main objective to make available a “FRMCS First Edition” ecosystem available for procurement by Q1 2025.

The UIC FRMCS 3GPP Task Force has been identifying and analyzing impact of this newly released set of FRMCS specifications on existing use cases and requirements collected in TR 22.889. The UIC FRMCS 3GPP Task Force analysis has concluded that refining existing use cases, defining new use cases such as merging railway emergency communications and real-time translation of conversation, and deriving potential new requirements, will be necessary to align FRMCS and 3GPP specifications. The potential impact on normative work is estimated to be limited and much less compared to the study work.

As approved in SA1#90-e (S1-202245), TR 22.889 has now been re-named to TR 22.989 from Rel-18 onwards (latest version is TR 22.989 v18.0.0) to make it visible to the Rail community to be able to follow the 3GPP normative work in line with their needs. It is of most importance for the Rail community that specifications from different organisations (i.e. UIC, 3GPP and ETSI) are all aligned.

Due to the expected 3GPP work overload in Release 18 (SA1 and downstream groups), it is proposed to reduce the scope of the present Rel-18 study to evolution of critical applications related use cases only already identified by UIC – what is really essential for the railways as part of the “FRMCS First Edition” and the migration phase from GSM-R to FRMCS. 

Study of non-essential use cases (e.g. evolution of performance and business use cases) shall be postponed to Rel-19.

This plan is from 2019 so quite likely that it is already outdated. It does provide an idea on different steps and trial plans. Some of this was also covered in the 5G RAN Release 18 for Industry Verticals Webinar detailed here.

Finally, as this image from Arthur D. Little highlights, there is a lot of other interest in addition to FRMCS for 5G in railway. Report here.

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