The team at Real Wireless has been looking back at wireless connectivity progress over 2020 in a number of sectors. There’s little doubt that overground rail communications services are among the slowest to develop – certainly in comparison to road, air or ports (or even underground rail), for example. The UK in particular offers more challenges than most other markets due to the very specific way in which its rail industry is organised.

So what makes a railway-focused wireless solution work well in a complex and challenging rail environment?

For operations-focused rail connectivity specifically, GSM-R is the global standard – and, in the coming years, the next-generation standard, FRMCS (Future Railway Mobile Communication System) will start to be deployed.

GSM-R is a secure platform for voice and data communication between railway operational staff, including drivers, dispatchers, shunting team members, train engineers, and station controllers. GSM-R is standardised and has been around for a very long time.

FRMCS is going to replace GSM-R. It is expected to be a 5G-based solution, with European trials taking place between 2023 and 2025. FRMCS spectrum allocation has already been agreed on a European level (ECC Decision (20)02), but member countries need to implement this decision for FRMCS rollouts to happen thereafter. Co-existence may be an issue as these two standards are going to be both in operation for several years as national changeouts occur, but at least there is a roadmap.

On the passenger connectivity side, things are a little more problematic. GSM-R and FRMCS have not been designed for passenger applications such as streaming videos. Trackside-to-train connectivity for passenger connectivity can involve standard cellular, millimetre wave and Wi-Fi technologies. For the non-cellular solution, this could mean proprietary Wi-Fi or millimetre wave solutions and, as a consequence, a range of spectrum options and all that they imply for cell range and capacity.

Cellular technologies have the benefit of being standardised, but mobile macro networks weren’t designed for rail connectivity. Trains present challenges in a typical cellular network; a train is essentially a moving hotspot, think of a small moving village, with up to 1,000 people, travelling at up to 150mph, requiring ongoing coverage and capacity along all rail routes. This puts trackside cell sites under enormous pressure for short periods of time and then leaves them underused for much longer periods. In addition, railway routes often include deep cuttings or tunnels, where coverage from the existing macro network is incidental at best. Therefore, these areas typically need their own infrastructure for dedicated passenger connectivity.

Trains are also problematical as they are very reflective and impose significant losses on radio signals. An antenna on the train roof, connecting to trackside infrastructure, is the optimal approach and an absolute requirement for Wi-Fi and proprietary millimetre wave solutions. These solutions would just not work without train roof antennas and associated on-board equipment.

But cellular solutions, with the right density of trackside infrastructure and the right choice of spectrum could still penetrate the train and provide on-board coverage without the need for external antennas and on-board equipment. Another approach for cellular coverage, based on my own experience in Switzerland, is to use cellular on-board repeaters to overcome the train penetration losses. But these have been rarely implemented in the UK, where it is far more common to install roof antennas and on board cellular to Wi-Fi gateways to provide on-board passenger Wi-Fi. Any on-board equipment will come at a cost, but for cellular solutions, it will reduce the (trackside) network density requirement and its cost.

Passenger connectivity isn’t just tricky to manage – it’s also expensive. On top of which, there are also problems to do with the UK’s train industry itself. Switzerland, like a number of other countries, have one railway company. However, the UK industry is fragmented, with the rail network infrastructure separate from the multiple passenger franchise companies operating rolling stock on this rail infrastructure. This makes a centralised, standardised and structured approach to railway coverage far more challenging.

Rail connectivity is a complex and slow-moving environment, so any attempt to predict 2021 trends could be a touch optimistic. But there are two useful DfT funded studies that Real Wireless is working on with our project partners: one study is focused on “train penetration” and the other research project analyses “tunnel propagation and coverage solutions”. The results and conclusions will be published this year and could affect how passenger communications develops in the coming years. Industry work on access to trackside infrastructure – rail tower assets – to enable coverage is also under way.

Mobile operators are also looking at shared trackside sites and shared antennas. Our inputs and our experience are supporting the efforts of a number of rail companies and operators in that space.

We will continue to use our expertise in the railway sector to work on these challenges and improve railway connectivity.

There may not be a major breakthrough – especially on the passenger connectivity side – in 2021 but, if you’ll excuse the pun, we’re on the right tracks.

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