The rail transport sector has for some decades made use of communications systems based on widely available cellular technology to satisfy primary operational requirements including safety and efficiency. However, with the universally adopted solution expected to go unsupported by the cellular network providers from 2030, there is a pressing need to consider what comes next. Huawei has developed, and in some cases already deployed, next-generation solutions based on newer 4/5G technology.
The current cellular solution for the railway industry, GSM-R, was implemented from the 1990s. Based on 2G/GSM technology, GSM-R forms the communications element of the European Rail Traffic Management System (ERTMS). The ERTMS complies with standards developed by the UIC, the rail transport industry’s international body, that are now used in over 30 countries across several continents.
Universal digital solution
GSM-R addressed the desire to replace, with a common digital solution, a large number of analogue in-track cable and radio communications systems. It satisfied the need to cost-efficiently achieve cross-border interoperability, and, by carrying signalling information directly to the train driver, enabled higher train speeds (up to 310mph/500km/h) and greater traffic densities with a high level of safety.
GSM-R provides a secure platform for voice and data communication between railway operational staff, including drivers, dispatchers, shunting team members, train engineers, and station controllers. It delivers features such as group calls, voice broadcast, location-based connections and call pre-emption in cases of emergency.
The technology is typically implemented using dedicated base station masts located close to the railway. Communication within tunnels is effected using directional antennae or ‘leaky feeder’ transmission. With base stations every 4.3-9.3 miles (7-15km) there is a high degree of redundancy, and higher availability and reliability.
Ownership challenges
The advantages of taking a mass-market, rather than a bespoke, approach to communications needs are obvious and compelling. Provided that operational needs can be fully met, there is no need for an organisation to develop, deploy, maintain or — eventually — responsibly dispose of significant and costly technology assets which have but one application. Infrastructure operators can instead engage in communications-as-a-service relationships with appropriate and trusted providers.
This is becoming apparent in the road transport sector where, for instance, protracted gestation has resulted in the still relatively limited deployment of ITS-G5 (5.9GHz DSRC-based) systems for vehicle-to-vehicle/infrastructure communication.
ITS-G5, a bespoke standard, has come under strong challenge from more recent 5G-based alternatives. 5G, unlike preceding cellular generations, provides the same near zero-latency communications performance necessary for safe operations in high-speed road environments. It means that roads operators are no longer constrained to a single solution.
However, there is a problem for organisations which do not fully own their communications networks: enforced obsolescence.
As cellular network owners and operators look to move to newer generations of technology in line with customers’ demands for better connectivity, greater bandwidths and broader feature sets, they will cease to support older infrastructure. GSM, and by extension GSM-R, will start going defunct little more than half a decade from now.
Leapfrogging a generation
By any measure GSM-R has been a success, having given 20-plus years of good service. However, it is not without limitations.
GSM-R’s 4MHz bandwidth limit renders it inadequate for large railway stations, hubs and rail merging areas; co-channel and adjacent-channel interference complicate network planning.
Further, GSM-R cannot support new services such as moving block-based train control systems, real-time train status monitoring, intelligent operations and maintenance, or railway IoT; nor can it support value-added services like multimedia dispatch communications, intelligent infrastructure management, trackside IoT, predictive maintenance, or passenger information transmission.
To address all of this, the UIC has been working on a new international standard, the Future Railway Mobile Communication System (FRMCS). Based on 5G NR, FRMCS effectively leapfrogs several generations of cellular technology.
Much has already happened. On 20 November 2020, the Electronic Communications Committee of the European Conference of Postal and Telecommunications Administrations allocated the paired frequency bands 874.4-880.0MHz and 919.4-925.0MHz, alongside the unpaired frequency band 1900-1910MHz for Railway Mobile Radio use (RMR is an umbrella term covering both GSM-R and FRMCS technologies). On 28 September 2021, the European Commission mandated that EU member states must make these frequencies available for railway applications.
The UIC released the first set of FRMCS specifications (UIC FRMCS V1) in 2023 and plans to release V2 in 2024. V3 — the first commercial version — is expected by the end of 2026. These specifications will define a comprehensive FRMCS 5G system, aiming to support trials and tests across various countries, and ultimately, promote and implement the system throughout the railway industry.
Migration strategy
FRMCS uses a three-strata decoupled architecture which supports significantly more applications than GSM-R and enables railway operators to choose between 4G, 5G, or other radio access technologies as necessary.
This feature enables the technology to reflect the cellular ‘landscape’ in different users’ geographic locations and provides a migration path to 5G once this is fully deployed. It is important, given the now-limited life of GSM-R and relative maturity of 4G and 5G networks.
The FRMCS specifications are intended for global use. However, certain countries may struggle to access the 5G framework and technologies due to factors such as unavailability or high cost of 5G spectrum, national 5G development schedules, and the cost of owning 5G technologies.
LTE (4G) has already been commercialised with great success. Used on railways across various regions, including South Korea's railway express line, China's heavy-haul railway and urban rail transit, and France's urban rail transit, it provides a solid foundation for ecosystem development. Some 4G products are already designed to support the forthcoming migration to 5G.
5G is in deployment and being put into commercial use. 5G greatly expands the frequency range and — in the future — will provide end-to-end railway mobile communications capabilities for FRMCS networks.
To address these constraints, in July 2024 the UIC released a specific technical guideline: FRMCS-Transition (FRMCS-T).
FRMCS-T is based on the established LTE standard and can utilise the same spectrum as FRMCS 5G. It facilitates quick deployment and implementation of FRMCS on 4G networks, filling the gap in the railway industry until FRMCS 5G specifications are finalised. Moreover, by using radio equipment compatible with both 4G and 5G, FRMCS-T requires just one site visit for quick deployment and can be upgraded via software for a smooth evolution, thereby protecting users’ investments.
Delivering the future
Keen to support continuity of safe, efficient services from strategic transport assets, as well as provide the increased levels of functionality that are now expected, Huawei, which has served more than 300 urban rail lines and over 110,000 miles/180,000km of railway in more than 70 cities around the world, has been bringing together a portfolio of solutions based around FRMCS.
Progress is demonstrated by presentations given by the company and its customers at recent industry events.
In September, at the InnoTrans 2024 event in Berlin, senior Huawei personnel talked about railway industry trends and the company’s strategy for addressing them. A white paper interpreted the FRMCS-T standard while proposing a 5G-oriented solution which enables smooth upgrades.
A high-quality communication system featuring large bandwidth, wide coverage and low latency is the key to broadband development of rail transit, and cloud-based services are an inevitable trend. At the same time, big data and artificial intelligence can be used to realise the true value of data, support intelligent business development and improve modal integration. Huawei has launched a next-generation optical communication bearer network solution based on its MS-OTN platform. Using IPv6+ technologies, this supports converged access of multiple service such as E1/SDH/MPLS-TP/fgOTN. Offering high bandwidth and reliability, low latency and easy operation and maintenance, it fully supports smooth transition from GSM-R to FRMCS.
An example of an already in-service LTE solution based on FRMCS architecture from Huawei comes from Mozambique Ports and Railways (CFM).
CFM operates several large, regionally significant ports on the Indian Ocean, as well as nine railway lines which ferry goods to such as South Africa, Eswatini, Zimbabwe and Malawi.
A modern, stable, sustainable system, providing reliable train-to-ground voice and data communication, was needed. The system designed by Huawei uses an advanced converged communication platform to provide MCX wireless broadband trunking and multimedia dispatching communication services. It supports 3GPP-compliant mobile communication networks and enables crucial communications and rich multimedia dispatching.
The system also supports specific railway business functions, such as function codes and emergency calls. It provides panoramic, visualised, controllable dispatching and commands for dispatching personnel, locomotive drivers and transport management. This improves security and efficiency.
The ability to quickly transmit real-time information has reduced the number of collisions between freight and passenger trains, and has increased the efficiency of maintenance personnel. Mozambique has already started to benefit from FRMCS’s ability to improve scheduling efficiency and safety. Freight volume at the Port of Maputo, for instance, has increased by almost a third.
The CFM system has become a regional benchmark. It demonstrates the maturity of FRMCS as a standard and how Huawei, as a competent and trusted supplier, is in the vanguard of change.
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Content produced in association with Huawei
