# Architecture

Canonical: https://frmcs.org/knowledge/architecture
Last reviewed: 2026-10-02
Status: editorial reference page (static legacy content, no stored approval record)

## Short answer

FRMCS architecture is commonly described in layers: a Transport Stratum that carries IP connectivity, and a Service Stratum that provides communication services to railway applications. Onboard/trackside and application views are different perspectives on the same system, not additional strata.

## Two strata

- **Transport Stratum** – the access and core network layer that provides connectivity, including radio access and IP transport [2][3].
- **Service Stratum** – the communication services layer (for example voice, data and mission-critical services) consumed by railway applications [2].

## Other viewpoints

Separating viewpoints prevents category mistakes in planning documents:

- **Onboard vs. trackside** describes *where* equipment sits (train-mounted gateway and radios vs. network sites and core).
- **Railway applications** describes *what* is being served (e.g. train control, voice communication, telemetry).

> Editorial assessment: many planning discussions mix these viewpoints. Naming the viewpoint explicitly in each requirement makes vendor responses easier to compare.

## Where to verify

Consult the current system architecture documents from ETSI TC RT and the UIC FRMCS pages for the authoritative definitions [1][2].

## Sources

1. [FU-7100 – FRMCS User Requirements Specification](https://img1.uic.org/IMG/pdf/fu-7100-5.0_0.pdf) — UIC, 5.0.0 (19 Feb 2020)
2. [ETSI TS 103 764 — System Architecture](https://www.etsi.org/deliver/etsi_ts/103700_103799/103764/01.01.01_60/ts_103764v010101p.pdf) — ETSI TC RT, v1.1.1
3. [3GPP TS 22.289 – Mobile communication system for railways (ETSI TS 122 289)](https://www.etsi.org/deliver/etsi_ts/122200_122299/122289/19.00.01_60/ts_122289v190001p.pdf) — 3GPP / ETSI, V19.0.1

## Cite as

Architecture. FRMCS Atlas. https://frmcs.org/knowledge/architecture (last material update 2026-10-02)

> FRMCS Atlas is a personal editorial project by Ante Samardzic (employed by Frequentis), not an official Frequentis, UIC, ETSI or ERA publication or endorsement. Claims are source-linked; review status is stated per page — database articles pass a stored quality review and human approval of the exact version, legacy static pages are marked as such.