About the project​


The Future Railway Mobile Communication System (FRMCS) will be the 5G worldwide standard for railway operational communications, conforming to European regulation as well as responding to the needs and obligations of rail organisations outside of Europe.

The work on functional & technical requirements, functional and system specification, standardisation in 3GPP as well as regarding harmonised spectrum solutions is currently led by UIC, in cooperation with the whole railway sector. A major challenge is the update by the European Railway Agency of the Technical Specification for Interoperability of Control Command and Signalling (CCS TSI) by the end of 2022 with a full description of FRMCS with respect to functionalities for interoperability. 

Therefore, the main objective of 5GRAIL is to validate the first set of FRMCS specifications (also called FRMCS V1).

Therefore, the main objective of 5GRAIL is to validate the first set of FRMCS specifications (also called FRMCS V1) by developing and testing prototypes of the FRMCS ecosystem, for both trackside infrastructure and on-board. Regarding on-board, 5GRAIL aims to reduce specific equipment costs and installation engineering time by combining all train-to-ground communications by enabling a modular on-board setup based on standardised interfaces and including mainstream 5G components, called TOBA (Telecom On-Board Architecture), in alignment with the sector’s technical vision.

The validation of the latest available railway-relevant 5G specification will be achieved through emulation of cross-border trials covering significant portions of railway operational communication requirements and including the core technological innovations for rail expected from 5G release 16 and pre-release 17. 

The project will first define the functional tests and then work towards prototypes development and evaluation, for both on-board and infrastructure, including vital (ETCS, European Train Control System, and ATO, Automatic Train Operation) and essential (FRMCS voice specific services and TCMS, Train Control and Monitoring System) applications. Interfaces between TOBA and ETCS, ATO and TCMS will be developed to contribute to the high-level targets detailed above. 

Prototypes will be then tested in simulated and real environments, with pilots in labs and in the field rolled out in various European sites (France, Hungary and Germany), in order to ensure compliances and validation for specification, standards and performance, and consequently guarantee the time to market for FRMCS products, planned for 2025 as per European timeline.

The project will finally deliver test report conclusions to update FRMCS V1 specification where needed and to identify technical constraints related to implementation issues. 

5GRAIL outcomes are viewed by the railway sector as a key milestone in the global plan leading to FRMCS market readiness for railways in Europe.



Elaborate prototypes of the future FRMCS V1 ecosystem, including telecom 5G infrastructure compliant with FRMCS 3GPP specific standardisation elements, but also new on-board equipment (TOBA, and additionally prototypes of adapted ETCS and ATO elements)


Define all the relevant technical and functional tests to be achieved to verify the conformity with FRMCS V1 specification, maximising the scope of applications to be tested or simulated (particularly operational voice services, ETCS, ATO, TCMS, video and interaction with automotive) and including some measurements of performance


Execute these tests in lab environment firstly, and then in real-world environment with train runs


Analyse the outcomes of these tests to loop back on FRMCS V1 specification, to amend or modify those, and then obtain a finalised version of FRMCS V1 specification for sector regulation. The overall 5GRAIL structure is shown in the figure below


5GRAIL will span a period of 30 months and is divided into 8 WPs, six of which will focus on research and development, test, field implementation and evaluation and two on coordination and dissemination:

  • WP1 FRMCS tests definition, tests results consolidation and specification review
  • WP2 TOBA prototypes development
  • WP3 Validation of ETCS, Voice, TCMS and CCTV/Video within TOBA – Laboratory tests
  • WP4 Validation of Data, ETCS, ATO and Cybersecurity within TOBA – Laboratory tests
  • WP5 Field Implementation and Evaluation
  • WP6 Rail and Road communication systems coexistence
  • WP7 Dissemination, Communication and Exploitation
  • WP8 Project Management & Coordination
The figure of how the project is organised

Our vision for the future

FRMCS, that will be materially proven by 5GRAIL, is seen by the railway sector as the enabler of train digitalisation, and consequently as one, if not the one, of the major “Game Changers” of DG MOVE strategy for railway Command-Control System evolution.

The deployment of 5G FRMCS will open the possibility for railway operators to implement a non-limited list of new applications permitting to optimise train operations and maintenance on one side, and to increase the quality of service to passengers (security, availability, punctuality and information) on the other side, such as for instance: 

  • Automated trains: this major evolution of railway transport, for both freight and passengers, cannot be achieved without FRMCS; 
  • New applications related to security, including video capacity, will become possible; 
  • Remote monitoring and surveillance of vehicle elements (TCMS applications) will be made possible only with FRMCS deployment; 
  • Etc. 

As an example of evolution and innovation potential, the figure provided below depicts the integration between TCMS and TOBA that will be evaluated in the frame of 5GRAIL, with telemetry and file transfer services among others. 

Additionally, 5GRAIL will pave the way for the industrialisation of new railway telecom products, such as: 

  • FRMCS compliant 5G infrastructure solutions (core and access) ;
  • Design of new radio modules adapted to railway bands (foreseen as of today as being in the 900 MHz and 1900 MHz bands, as per the on-going assessments achieved in CEPT / ECC normative groups, and in preparation of European harmonisation for FRMCS bands);
  • Design and prototyping of a new Telecom On-Board Architecture (“On-board router”), managing all the railway operational telecom streams in the vehicle, providing bearer flexibility, prioritisation of applications according to their criticality in alignment with trackside elements and including some cybersecurity material protections;
  • Adapted ETCS, ATO and TCMS equipment to the new telecom on-board architecture. 

Border Crossing

5GRAIL also addressed different aspects related to border crossing. In WP3 Nokia lab the following topics and building blocks have been successfully tested:

  • With the realised FRMCS-GSM-R Interworking, a system transition between GSM-R and FRMCS could be shown during an ongoing railway emergency call, which also covers scenarios where neighbour networks have different technology in use.
  • As part of the Bearer Flexibility tests, a seamless handover between different TDD (Sub-) Bands using different TDD Frame Structures could be demonstrated without any impacts on mobility.
  • Finally, as also studied by other H2020 ICT-53 CAM projects, the aspect of seamless (Inter PLMN) handover was evaluated and tested with two important building blocks: For this the 5G Radio and Core network was configured to allow for handover via the core network (Ng interface handover, in contrast to deployments where handover is realized via a direct interface between gNb). Ng handover is typically demanded when connecting different networks.
  • Additionally, Ng handover was configured using two 5G core systems by Inter AMF mobility, where the active data session was seamlessly moved between the two cores without interruption. Due to the situation that the 5G SA deployments selected for 5GRAIL lacks the maturity of a full support of roaming capabilities, the two core systems where configured as an intra PLMN setup with one MCx server, as depicted in the figure on the right.

WP4 lab considered various border-crossing scenarios based on the usage of several UEs within the FRMCS OB-GW in order to look forward achieving a seamless transition from the application point of view.

Firstly, Alstom’s TOBA implemented bearer flexibility concept with two 5G modems, each being able to attach on its own PLMN. Thus, having configured a preferred link, data application will immediately use it as soon as this path becomes fully operational, somewhere in the overlapping area, preventing any impact at the application level, as shown in the figure on the left.

The other flavour to be tested relies on the multi-connectivity concept and was designed on Kontron’s TOBA. In that case, the FRMCS OB-GW can use all available paths at the same time. Multipath will then ensure smooth border crossing at the application level, as shown in the figure on the right.