The wireless communications system developed for rail is GSM-R (Global System for Mobile Communications-Railway). Although GSM-R is still in the roll-out phase, in France in particular, thought is already being given to how best to respond to the need for higher throughput. Choosing this new system is one of the most important decisions that will have to be taken in the next few years by the rail transport community and authorities in charge of this sector. According to the European Union Agency for Railways (EURA), the GSM-R standard will cease to be maintained by the GSM-R Industry Group after 2030. The rail transport community aims to define the future system by 2019 for it to be referenced in European regulations as of 2022.
As the name implies, GSM-R is based on GSM, the 2G standard for mobile communications. It enables drivers (in their cabs) and maintenance workers to speak to each other (group calls) or to rail traffic regulators. GSM-R also implements the European Train Control System (ETCS) which unifies trains and railway signalling and makes them smarter and safer. This system is part of ERTMS (European Rail Traffic Management System) which should, eventually, replace the automatic warning signalling systems on board trains. For example, in the event of an emergency, the GSM-R system would broadcast the radio alert that brings all train traffic to a stop in a given area.
In accordance with current European regulations, all GSM-R networks in Europe use the 876-880 MHz frequency band for the train-to-ground link and 921-925 MHz for the ground-to-train link. Thanks to this guaranteed interoperability, trains can cross European borders without having to change their radiocommunication system.
Upgrading to higher data rates aims to increase safety, enhance performance and improve the efficiency of rail transport. Eco-driving and real-time monitoring of energy consumption will also be enabled. The new high-speed network, the Future Railway Mobile Communication System (FRMCS), will be used by railway operators to communicate between trains, or with mobiles and other trackside communication devices
The next decision to be taken is related to the technology to be adopted for the next generation. The rail transport community’s current preliminary thinking is based on the LTE standard, in use for 4G on mobile networks, which would have to be adapted to the needs of rail. Another option would be to choose 5G, which would appear to meet new rail transport requirements in view of the low latency and reliability of service features that it is expected to provide.
A second point for decision will be the spectrum to be used for the future system and the process for coexistence and migration. Among the possibilities, the most promising would be the introduction of new technology in bands currently exploited or, possibly, in other bands dedicated to private networks (PMR), such as the 400 MHz band or bands above 1 GHz, or perhaps the use of commercial networks (4G or 5G). Work will be needed on European harmonisation and also on coordination between member states on migration, before introducing the successor to GSM-R.
Communications-Based Train Control (CBTC) is an application in use for urban rail networks (metros and tramways) to locate and direct trains via a two-way high-speed communication system between trains and the ground infrastructure.
This application for metro trains contributes to ensuring fully automatic light rail systems for example in Paris and also in Lyon and Lille. It operates in the 5915-5935 MHz radio spectrum band. This essential application for the development of tomorrow’s urban transport systems is not, as yet, contained in any harmonised framework. In a handful of countries, CBCT is occasionally implemented in the 2.4 GHz band although it is hardly suitable for a critical communication system to be running on a general authorisation framework.
In the long term, there is also the possibility that the technology could converge within the ERTCMS system. The feasibility of this option and its impact on spectrum management should be explored.