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6 July 2020

Railway operators target 2025 for full-scale 5G communications to trains

Leading cellular technology vendors are clambering on board the global initiative led by the International Union of Railways (UIC) to move rail communication forward to 5G for critical operational and passenger services. Ericsson is the latest mover joining UNIFE, Europe’s rail association developing critical network capabilities for the industry based on the 5G-based FRMCS (Future Railway Mobile Communication Systems) aiming to improve railway operation quality, efficiency, passenger experience and network security.

The announcement came with a bland statement from Manuel Ruiz, head of Mission Critical Networks at Ericsson, that mission-critical networks based on 5G will “enable the rail industry to meet the challenge of digitalization and business transformation.”

Currently they are having to manage on 4G or even 3G, which has limited the scope of operational services for navigation and safety, as well as the quality of broadband access for passengers. Gripes over on-board WiFi quality have been legendary ever since such services were first introduced early in the noughties and have become a much bigger embarrassment for rail operators as consumer expectations have risen.

A UK survey conducted for in December 2018 found that 86% of rail travelers struggle to connect to the Internet via either WiFi or 3G / 4G mobile on their smartphones while commuting to work. The experience was often equally bad whether users connected directly over cellular services via 3G/4G or indirectly via the train operator’s WiFi, highlighting the continuing lack of mobile bandwidth provision and failure to solve the problems of handover at speed. Contention for access to the on-board WiFi itself had generally ceased to be an issue and it was the cellular connection to the train that was usually the bottleneck.

Quality of service should improve markedly as 5G is deployed but for train operators the greater goal is to make productivity and safety gains through automation and improved surveillance of the overall track to identify hazards ahead. Improving passenger experience is obviously desirable but as all operators are in the same boat that has not applied much competitive pressure, which is partly why service quality has remained so lamentable.

FRMCS is the designated global successor to GSM-R (the Global System for Mobile Communications – Railway), the legacy digital radio system whose specifications date back to 2000. GSM-R has typically been implemented with dedicated base station masts close to the railway spaced 7 to 15 kilometers apart to ensure some redundancy. Coverage in tunnels has been provided through directional antennas combined with ‘leaky’ feeders, coaxial cables functioning effectively as extended antennas.

It is fair to say that GSM-R has enjoyed more success operationally than in eliciting passenger satisfaction, having enabled introduction of ETCS (the European Train Control System), both in Circuit Switch and Packet Switch (GPRS/eGPRS) modes, for on-board signaling for example. It has also underpinned the Railway Emergency Calls (REC), which alerts all train drivers moving towards a given danger point in seconds, capable of automatically instigating braking depending on national operating rules. It also supports voice and data communications between drivers and signalers as well as trackside workers, as well as broadcasts to all trains in a given area.

5G though has the potential to extend and reinforce these applications while ushering in others, between them exercising all three fundamental use cases as well as the high availability essential for mission critical processes like responding to emergencies and autonomous operation. Like autonomous driving, the latter requires ultra-low latency and guaranteed availability, but is likely to enter service more quickly because the environment is more controlled with fewer exceptions or ‘unknown unknowns’ to cater for.

An underlying challenge for most of these applications that 5G does not solve on its own is that of hand over at high speed. This is being addressed in various pilot projects, including one involving German optical and carrier Ethernet product vendor ADVA on a route spanning three stations in the Barcelona area of Spain. This combines microwave and optical, running a backhaul network along the tracks using PON (Passive Optical Network) technology, feeding millimeter wave (mmWave) RAN access points employing intelligent beamsteering to direct signals to rooftop antennas on the trains.

ADVA claimed in January 2020 that this was Europe’s first 5G rail deployment in an operational environment. This was part of the EU’s Horizon 2020 5G-PICTURE project, also involving Blu Wireless Technology, CNIT, COMSA Industrial and the local railway operator Ferrocarrils de la Generalitat de Catalunya (FGC).

A key finding was that this arrangement truncating the radio links to trackside backhaul access points solved the handover problem and delivered a good QoS to passengers, as well as meeting demanding latency targets for operational systems over the same common infrastructure. The backhaul used WDM (wave division multiplexing) for scaling of capacity.  By spacing the access points sufficiently closely together, the network could also guarantee the high levels of availability that have proved elusive under 4G.

A few months earlier in 2019 Vodafone had been engaging in a similar deployment in Germany in collaboration with French multinational defence, security, and transportation electronics group Thales. This was focused initially on demonstration of remote control of a freight train, deemed a suitable early target for automation because of lower operating speed, often at off peak times. This demonstrated 5G’s network slicing to partition services within given spectrum to cater for varying priorities and QoS. In this case it insulated the remote control from other applications in the vicinity, including casual internet surfing.

Driverless operation of trains has been a reality some time over some dedicated routes, including airport shuttles between terminals and some metro lines in cities. But extension to mainline rail services will be controversial and likely to be opposed initially by unions and possibly passengers. There is likely to be a transition period where drivers are still present to take over in an emergency, even if in practice the automated system might be better placed to respond quickly to feedback from the network.

Such feedback could be driven by drones flying over tracks to provide early warning of damage, objects, or even “children playing on the line”. Ericsson has already conducted a live 5G test with flying drones transmitting high-resolution images from a freight yard, with machine learning algorithms tuning the system to identify possible hazards without too many false positives that would render it unusable.

In terms of 5G’s underlying use cases, the future FRMCS systems plans to employ eMBB (enhanced Mobile Broadband) for passenger services and also mission critical imaging functions. Then URLLC (ultra-reliable low latency communications) will come in for the REC emergency functions and remote control, while mMMC (massive M2M communications) will be invoked for monitoring sensors in predictive maintenance.

The latter is designed to cut maintenance costs by anticipating when repairs are needed. Some operators have gone from pre-emptive maintenance involving routine servicing in the hope of averting faults to reactive maintenance repairing faults when they occur. The former incurs high costs and often still fails to prevent problems occurring, while the latter causes operational disruption when the faults do occur. The aim is to anticipate faults before they happen through more intelligent monitoring of track as well as transmission equipment and rolling stock, aiming to intervene in such a way as to prevent faults without wasting resources on routine servicing.

The distinction between predictive and pre-emptive maintenance can be illustrated with reference to modern automobiles that have with onboard detection of component wear. Under pre-emptive maintenance, consumable components such as brake pads might be replaced automatically at each scheduled service, irrespective of how much wear they have left. With predictive maintenance the cars are called in for pad replacement only when they are close to full wear, saving money and reducing waste.

There are also hopes of operational savings through more intelligent onboard signaling and automation even with drivers still on board, enabling distances and times between trains to be reduced for example. This could also improve punctuality and frequency on busy lines.

Broadly, rail applications come under three headings: critical, performance and passenger, with 5G likely to enhance all three. Under critical come emergency communications, shunting, trackside maintenance, and in future Automatic Train Operation (ATO), Automatic Train Control (ATC) and Automatic Train Protection (ATP).

Under performance come applications such as train departure procedures and telemetry that improve punctuality and reduce risk of delays, beyond actual movement of the trains. Then under consumer come mobile internet, ticketing, and passenger information.

Eyebrows might be raised by the relaxed time scales for GSM-R’s replacement by FRMCS, which will mostly come into play between 2025 and 2030. But railways operate on long lead times with investments planned over years or even decades. Furthermore there has to be clear agreement over operational procedures, especially in Europe and to a lesser extent other continents where single train journeys can span several countries.

So support for GSM-R will continue until 2030, while 5G is expected to serve railways for a similar period, from the mid-2020s until 2050, which is as far as the roadmap for Europe’s ETCS currently extends. For several years, GSM-R and FRMCS will run in parallel.