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5G: The era when your internet will be quicker than your train

Prof Mischa Dohler, fellow of the IEEE & RSA, King’s College London and Worldsensing, Prof Dimitra Simeonidou, from the University of Bristol and Bristol is Open, and Prof Rahim Tafazolli, of the 5G Innovation Centre at the University of Surrey, discuss the rail recommendations within the Future Communications Challenge Group’s (FCCG’s) ‘UK strategy and plan for 5G & Digitisation’ interim report.

Given that cellular systems take a long time to design, standardise, manufacture and roll-out, it is no surprise that 5G has become a talking point in government, industry and academia even before 4G has properly been rolled out.

In broad terms, 5G follows the same design roadmap as 4G has from 3G and 3G from 2G, i.e. a one or two order of magnitude improvements in data rate, latency (delay) and the number of devices which we can connect. If 3G delivered 100Mbps, 4G does 1Gbps and 5G is thus expected to do 10Gbps. 

From a consumer perspective, expect a significantly improved experience which – so we hope – will reach wireline experiences and make you forget that you are on wireless. From an industry perspective, however, 5G will be different in that the technical capabilities will surpass thresholds for the first time, which is interesting for industry rolling out critical control applications, as well as massive Internet of Things deployments. 

The standards defining organisation (SDO) which takes care of standardising these wireless systems is 3GPP. Interestingly, 3GPP never makes any reference to specific generations. Rather, the industry underpinning the SDO works in ‘Releases’. Once a technical release has met the requirements outlined by the ITU, only then is the system formally called 5G or 4G. 

Cellular and rail standards roadmaps 

The 3GPP roadmap is shown in Figure 1 (overleaf). Release 13 was ratified summer 2016. Release 14 is currently under design. Release 15 will be the first 5G working stream, with products available 2018-19 and first commercial deployments commencing 2020-21. 

In more detail, the train-specific service requirements are handled in technical report TR 22.989 ‘Study on Future Railway Mobile Communication System’ as part of 3GPP SA1, which focuses on a gap analysis between existing 3GPP functions and Future Railway Mobile Communication System (FRMCS) user requirements. The report will likely be completed by March.

In addition, the technical report TR 38.913 ‘5G RAN Scenarios and Requirements’ looked at various train-specific deployment scenarios for a future 5G radio access network (RAN). Notably, it looked at the requirements on radio parameters, such as carrier frequency, inter-site distance, user density and maximum supported mobility speed. It also looked at critical train communications as part of a high-speed scenario analysis. 

Interestingly, it is anticipated that GSM-R, which underpins much of today’s rail communications backend system, will be discontinued towards 2030. Therefore, the rail industry has only about a decade left to overhaul its communications and safety system with a viable and proven system needed in about five years from now – not a lot of time in this industry! 

To this end, the International Union of Railways (UIC) has commenced to look at FRCSM and also engages with 3GPP and other related SDOs. 

5G train features and applications 

From an application point of view, 5G will be both an evolution as well as revolution. The beneficiaries are passengers/consumers, the railway operator as well as third parties in and out of the railway ecosystem. 

Notably, passengers will enjoy a much more reliable and consistent network experience. This will be enabled in 5G with higher rates, better and more resilient system designs as well as lower costs to the operators due to flexible architectures. Importantly, 5G can also act as a backhaul system for in-train wi-fi systems. 

5G will also enable traditional B2B services to work natively within the train ecosystem, where e.g. 3GPPP SA1 TR 22.989 outlines use cases along access to the system, uncontrolled power down, invitation to a voice communication, assured voice communication (AVC) for shunting operation, role management and presence, location services as well as interworking with GSM-R. 

Fundamental changes to how network systems are being controlled and maintained, however, will be enabled by ultra-reliable and low-delay 5G systems. These are expected to replace (often proprietary) industrial control systems, such as SCADA, and be able to connect the millions of sensors and actuators needed to make train systems safe and operational. Furthermore, 5G will facilitate native third-party access through secure and scalable multi-tenancy systems, which may constitute an interesting business opportunity for rail operators. 

Challenges ahead 

Designing next-generation communications and train systems does not come without risks. A few important challenges for both communities are summarised below: 

• Design & usage cycles: Train and cellular industries work on very different cycles. Indeed, testing, procurement, deployment and then usage of technologies in heavy industries is often over windows of several decades; in that time, cellular has already deployed several technology generations. To reconcile these inherently different cycles remains a challenge for both industries
• Data-driven services: The transformation from providing train connectivity to a train operator which also provides data connectivity, along with all possible services, is very challenging as business models need to be aligned and internal company structures need to be changed. In addition, part of the control data will be of use to consumers, and the other way round, which constitutes challenges from the perspectives of security, privacy and regulation
• Coverage: Cellular coverage is driven by cost. With 5G likely to deliver even smaller and more heterogeneous cells, providing real radio coverage will become even harder. Therefore, the cellular community ought to work on mechanisms which allow to improve the perception of coverage rather than providing real coverage
• Street furniture: To accelerate deployment of the small cells in 5G, regulation may aid operators by having public (and possibly also private) street furniture deregulated. That would lower the costs for network deployments
• Value-vs-cost: A feature-rich technology will have its cost. It is therefore important to conduct very tight co-design workshops between both industries so that cellular receives a real-time feature validation and train operators understand the value of 5G. This will also allow to validate 5G B2B business models 

In summary, whilst 4G is more of the same, 5G is not only about new technology but also about new usage patterns, service approaches and business models. The UK government’s announced investment in next-generation digital infrastructures will give a major boost in developing and deploying these technologies.

FOR MORE INFORMATION

The ‘UK strategy and plan for 5G & Digitisation’ interim report can be accessed at:

W: tinyurl.com/RTM-FCCG-5G