Rail Wireless

What do rail passengers in 2019 want from wireless? Voice, web browsing, emailing and social media are pretty much a given, but it’s the ‘streaming’ services that are forecasted to generate 75-90% of traffic on trains. Assuming an unconstrained usage policy, the forecasted demand may reach multiple Gbps for a 1,000-seat train by 2025.

Fortunately, there are technical solutions that can deliver high capacity wireless connectivity to trains. Good trackside coverage and capacity (in other words track-to-train coverage or train backhaul) is one of the essential components to delivering a high-performance wireless service. The other key component is the wireless onboard solution on the train itself, consisting of the onboard equipment (in the form of repeaters, small cells or Wi-Fi gateways) and train-mounted antennas. The purpose of the onboard solution is to eliminate the challenge of train penetration caused signal losses that could lead to poor (or lack of) passenger connectivity. Therefore, train-mounted antennas, linking the trackside coverage infrastructure to the onboard equipment, is indispensable. And delivering the best possible trackside signal to the onboard solution enables high quality onboard connectivity.

The other benefit of a wireless onboard solution is that trackside infrastructure (such as 4G/5G-based backhaul or possibly 5GHz and mmWave proprietary solutions) will be simpler and cheaper. It adds clarity and predictability to the planning process, not to mention limiting or obviating the risks of, say, shallow signal incident angles or the introduction of new, even-harder-to-penetrate trains. The cost reduction mentioned above is a result of a reduced trackside infrastructure requirement, as the train penetration losses are eliminated.

But how can we get the best from this connectivity? Although it’s still some way from widespread application, network slicing could come into its own here. Smart network slicing features could group and prioritise different types of traffic, notably real-time services like voice. Focusing on higher priority traffic would reduce the capacity requirement to much more feasible and affordable levels. But media streaming could still be supported when capacity is available, eg. using adaptive media resolution combined with best effort principles.

Onboard gateways that include media servers are another useful approach. These servers offer access to local media such as news, movies, music, games, weather forecasts and frequently visited web pages. Services like this have been trialled in the UK and seem to work.

Onboard content improves the steaming experience and the easier the streaming, the more popular the service. And if passengers stream from an onboard server, they are likely to make less use of their devices for connectivity that requires ‘external’ mobile broadband.

Passenger experience is a factor here too. If onboard servers offer good content and streaming performance, then the passengers will be pleased. They may not even realise that external connectivity is being side-stepped. And given streaming is one of the applications with the highest data demand, the delivery of local streaming services would also have the highest data demand off-load benefit on track-to-train capacity, delivered by the trackside infrastructure.

Prioritisation and offloading of traffic would improve (non-streaming) passenger broadband and voice service performance, both of which Wi-Fi can deliver. That said, quality voice is probably best delivered by MNOs, which would most likely mean using onboard repeaters connected to the train antennas (and hence to track-to-train coverage), which could also feed a 4G/5G router. The mobile broadband router could then connect to the train Wi-Fi kit and potentially to an onboard media server.

As a result of all of the above, rail coverage deployment (especially capacity dimensioning, impacting inter-site distance and number of sites) could become much simpler and cheaper. However, there are many approaches and some of them are still in the early stages. If you’re a rail operator, you may be unsure which, if any, of these solutions are available or right for you – which is where Real Wireless comes in.

Managing transport connectivity for passengers in a fast-changing wireless environment is what we do. While much in our 2016 report on rail connectivity remains relevant, we are constantly discussing ever more ingenious ways of giving rail passengers what they want from wireless. Get in touch to find out more.