It’s all about the money, money, money
So let’s get this clear from the start, passenger connectivity on rail has never been about the technical challenges, it is just about ‘who pays’ – the rail network operator, the mobile network operator, the passengers, a Government department or some other entity.
Yes, certainly there are some technical, architecture, deployment and logistical challenges such as providing good coverage in deep cuttings and tunnels, but these are all understood and there are a number of different technical solutions and commercial constructs offering different cost/performance points. However, deploying trackside on land owned by a rail operator can be expensive and time consuming – plus, depending on the spectrum being used, cell sites could be required every kilometre or possibly every 500m. That is how the costs start to grow rapidly, noting the requirement for fibre connectivity and power at each site – and then the logistics and costs for maintenance need to be factored in. Deploying using existing infrastructure such as overhead line equipment (OLE) gantries or existing GSM-R sites could reduce costs, but all options remain expensive.
Passenger connectivity – what’s that?
Let’s look at the basics – what do we mean by rail passenger connectivity? Essentially it is the ability for passengers to make voice calls and use mobile broadband whilst travelling on a train and waiting at stations. Of course reliability is key here – which implies being able to complete the call without getting cut off and download documents and watch a video without buffering – we’ve probably all heard the conversation ‘I’m on a train so you are probably going to lose me’!
Reliable connectivity can be achieved by good public mobile network coverage at the trackside with signal levels sufficiently high to be able to penetrate the carriage windows which, with today’s rolling stock having metalised windows to keep out direct sunlight can be challenging. However, mobile networks have typically not been designed to provide good coverage on rail routes, which for much of their length are in rural, low population density areas. Coverage in deep cuttings has certainly not traditionally been a goal for public mobile network operators. Furthermore, the costs of providing power and backhaul to new sites serving rail routes have always proved prohibitive.
An alternative choice is to provide Wi-Fi in the carriages with access points connecting to an onboard cellular gateway, which is then backhauled, using rooftop antennas, to the public mobile networks. The use of Wi-Fi calling and call apps helps, in that direct access to mobile networks might not be required to make calls. However, not all phones support Wi-Fi calling and not all travellers use calling apps. Today, free on-train Wi-Fi using gateways is the choice for many train operating companies, albeit with some limitations on the use of ‘data-intensive’ services such as video streaming. This generally came about following the Government’s announcement of funding for free Wi-Fi back in 2015 Free wi-fi to help rail commuters stay connected – GOV.UK (www.gov.uk).
It is also possible to deploy small cells in carriages that are backhauled onto public mobile networks or onto a private trackside network– such on train solutions would need to be multi operator and multi RAN technology leading to complex and expensive solutions that provide only limited advantages compared to on board Wi-Fi. Another option is the use of on-board repeaters, although these can be also be complex to deploy due to interference considerations..
There are many architecture and deployment variations that either rely on existing mobile operator ‘incidental coverage’ at the trackside or use specific trackside or ‘close to trackside’ dedicated wireless infrastructure deployments, designed to improve passenger connectivity. These could be dedicated public mobile network deployments or private network deployments.
Of course, whichever technical approach is used, connectivity in tunnels remains a specialist solution and clearly beyond what public mobile networks normally support directly. Radiating cable, Distributed Antenna System and inward facing Yagi antennas at the tunnel entrances are part of the tunnel coverage toolbox. As you can imagine deploying anything in or at the entrance to rail tunnels is an expensive undertaking with safety, space, temperature management and access for maintenance considerations all adding to the complexity and cost. Radiating cable with equipment located outside the tunnel is the ‘go-to’ solution for longer tunnels along with tunnel entrance yagi antennas for shorter tunnels.
Then there is the question of what throughput should be provided – with HS2 planned to carry up to 1,100 passengers per train – you can start to see how the notion of ‘the Gigabit train’ has evolved as both passenger numbers per train have grown and the necessary downlink speeds required to support video streaming from any number of sources have also grown.
DfT considers cutting Wi-Fi funding
However, recent events have made this complex eco system even more complex.
A Transport Focus report ‘Britain’s railway: what matters to passengers’ Britain’s railway: what matters to passengers (d3cez36w5wymxj.cloudfront.net) placed ‘reliable Wi-Fi and mobile reception’ 23rd out of 25 factors that passengers were asked to rank. Based on this report, DfT is said to be considering removing the funding it provides to the Train Operating Companies to provide on board Wi-Fi, citing current the financial unsustainability of rail and the need to cut costs. Another reason put forward by DfT to support these plans is that people choose to use their mobile phone service for connectivity rather than the Wi-Fi. Needless to say there were a number of published disagreements to this new strategy – including from Transport Focus itself! Train passengers could lose access to free wifi to cut costs | Evening Standard. Also perhaps interesting to compare today’s passenger rankings with those back in 2016 as reported at a seminar in London where both DfT and Real Wireless were amongst the speakers. How to get reliable wireless coverage on trains | TechRadar
Yet this apparent change of policy comes at a time when other countries such as Germany are funding test deployments targeting the 5Gbit/s train Germany starts project to provide 5G along train tracks (rcrwireless.com a). This will be based on 5G technology, mid-band spectrum and will reportedly require 20,000 new towers to be deployed. To quote the Federal Minister for Digital and Transport ‘ Dr. Volker Wissing : “Increasing rail’s appeal is about more than making sure trains are on time and reliable. Taking the train needs to be as pleasant an experience as possible and more convenient. We want trains to be able to serve as a travelling office or living room where passengers can work, stream videos and make calls without any technical issues at all. To achieve this high quality, we have to have gigabit coverage. The Gigabit Innovation Track project being funded will lay the crucial foundation for this.”
Spain seems to following a similar approach with 5G connectivity deployment contracts being awarded recently by ADIF to Orange and a Vodafone/SEMI JV covering various rail routes Adif AV invests €117.3 million in the deployment of 5G technology in high-speed lines – Adif
The recent Wireless Infrastructure Strategy from the Department for Science, Innovation & Technology mentions ‘rail’ over thirty times and it is clear that improving passenger connectivity on rail remains in focus for DSIT.
So where does Real Wireless fit into this?
Real Wireless understands the rail connectivity ecosystem and its challenges. We have undertaken numerous rail coverage modelling and costing projects to identify where best to locate 4G/5G infrastructure to maximise the Quality of Experience for passengers whilst minimising the costs for – well, whoever is paying.
We have provided detailed deployment costings and analysed which is the optimum spectrum to use in rail. We have worked with many parts of the rail eco system including Network Rail Telecom, various Train Operating Companies, HS1 and HS2. We have used the Yellow Train data published by Ofcom for some of our modelling projects, so called because it was gathered using antennas fitted to Network Rail’s yellow engineering trains and measures the signal levels of all mobile network operators along the mainline routes. We have worked for DfT as part of a consortium in two projects – one assessing the optimum architectures for deployment in rail tunnels and the second to understand the train penetration losses across the different rolling stock fleets used in the UK and assess the impact of these losses on the onboard mobile network user experience.
In several rail projects we have modelled the coverage and throughput as a percentage of the route length with downlink speed ranges – as shown below. This example was based on deploying a new 4G trackside network initially using the existing GSM-R sites on a particular route.
Then we modelled additional sites – new sites between the existing GSM-R sites – which as can be seen from the graphic below, for the same route, shows a really significant improvement in the overall throughput and therefore the quality of user experience.
We have also worked with MNOs and the Rail JOTS team helping to define technical specifications for multi operator rail deployments.
Where appropriate, we have implemented on train measurement campaigns using specialist test equipment and mobile phones fitted into backpacks and then we have analysed the results, comparing them to our modelling and/or yellow train data.
RTR, the Austrian regulator, commissioned Real Wireless to assess the costs of adding road and rail transport coverage obligations in a recent spectrum auction. We modelled how many new sites would be required and the associated costs for each MNO in Austria. We then had to present our findings to each MNO and get their agreement to our cost assessments. The figure below shows the additional sites required.
The figure below then shows the Present Value costs for one mobile operator for the various coverage objectives defined by RTR.
Putting all off our experience and capabilities together means we can bring unique real world insights into rail communications – whether that is for passenger connectivity or for the forthcoming replacement of GSM-R with the 5G based Future Rail Mobile Communications System (FRMCS).
Our techno-economic analysis capabilities, simulation tools and real world experience of deployment costs and the associated challenges allows us to rapidly come up with answers to the important questions regarding rail – which might be:
- What will it cost to provide a national 5G service on key rail routes direct to devices and supporting 1Gbps to the train based on using dedicated trackside infrastructure making use of OLE and/or existing GSM-R sites? What would the user quality of experience be?
- What would the savings be moving to an in-carriage Wi-Fi approach or small cells, rather than direct to device, using on board gateways and roof mounted antennas? How would the user quality of experience compare to the direct to device option?
- How should passenger connectivity and FRMCS deployment be considered together to optimise both systems whilst minimising costs?
- Do Non Terrestrial Networks and LEO constellations have a part to play in passenger connectivity – both on train and at stations?
