Glossary
FRMCS glossary
Key terms of railway mobile communication, each with a short definition and a link to the primary source. Editorial draft — check the source before relying on a definition.
- FRMCSFuture Railway Mobile Communication System
The UIC-led successor to GSM-R for operational railway voice and data communication, built on 3GPP mobile standards (5G).
Source: UIC FU-7100 – FRMCS User Requirements Specification v5.0.0 (19 Feb 2020)- GSM-RGlobal System for Mobile Communications – Railway
The current 2G-based digital railway radio standard used for operational voice and ETCS data, which FRMCS is intended to replace.
Source: Commission Implementing Decision (EU) 2021/1730 – recital 1 (GSM-R obsolescence; FRMCS as successor)- MCXMission Critical Services
The 3GPP family of mission-critical communication services (push-to-talk, video and data) that FRMCS uses for railway applications.
Source: 3GPP TS 23.280 – Common functional architecture to support mission critical services- MCPTTMission Critical Push To Talk
The 3GPP voice service within MCX providing group and private calls with priority handling.
Source: 3GPP TS 23.379 – Functional architecture and information flows to support MCPTT- 5G NR5G New Radio
The 3GPP radio access technology on which the FRMCS transport stratum is based.
Source: ETSI TS 103 765-1 V1.1.1 – FRMCS Building Blocks and Functions, Part 1: Transport Stratum- Railway frequency bands
Harmonised European spectrum for railway mobile radio in the 900 MHz and 1900 MHz ranges; 3GPP has defined corresponding bands for FRMCS use.
Source: ECC Decision (20)02 – 874.4–880.0 / 919.4–925.0 MHz and 1900–1910 MHz for Railway Mobile Radio (amended 28 June 2024)- On-Board Unit (FRMCS OBU)
The on-train equipment connecting on-board applications such as ETCS and voice to the FRMCS network.
Source: ETSI TS 103 765-3 V1.1.1 – FRMCS Building Blocks and Functions, Part 3: Train On-Board Functions and Interfaces- Gateway
A function that connects on-board or trackside applications to FRMCS communication services, decoupling applications from the radio technology.
Source: ETSI TS 103 764 V1.1.1 – FRMCS System Architecture- ETCSEuropean Train Control System
The European signalling and train-protection system whose data communication currently runs over GSM-R and is planned to migrate to FRMCS.
Source: ERA – CCS TSI Appendix A: mandatory specifications (ETCS B4 R1, GSM-R B1 MR1, FRMCS B0)- TSI CCSTechnical Specification for Interoperability — Control-Command and Signalling
The EU interoperability specification that references the radio communication requirements for railways, including FRMCS.
Source: Commission Implementing Regulation (EU) 2023/1695 – CCS TSI
More depth: FRMCS knowledge pages.