Why should we improve wireless connectivity along transport corridors? And how?
The answer to the first question isn’t difficult. Good connectivity is no longer a selling point; it’s an expectation. End users don’t know the complexities involved in guaranteeing a mobile signal in a train or in a car – and most don’t care. Most just assume they can make a call or receive data.
But these complexities are evident to network planners – and they aren’t negligible. Cars, for example, move quickly, and coverage doesn’t always move with them – most obviously in rural areas.
However, cars can at least be parked while an end user tries to find a signal. Trains are much more challenging. They can’t be parked on the roadside when you want to make a call or download some data. And unlike cars, there are no legal objections to users making a call while the vehicle is moving, so there will be no let-up in demand.
But meeting that demand isn’t easy. How do you manage the connectivity requirements of a large group of people in a small area, the size of a small village, moving at speed and therefore spending a very small amount of time in the catchment area of each mobile cell? To make matters worse, these people are often travelling in a sort of Faraday Cage – a metal box that reflects mobile signals.
5G itself is not going to solve the problem, but densification of cellular infrastructure will alleviate some of these problems. But what can improve train connectivity in the here and now?
It’s a question that Real Wireless has been examining for a number of years. Some of our experts were pioneering the first public (passenger) rail and tunnel connectivity programs over 20 years ago. Some were also working on GSM-R, the first rail-specific mobile standard, and many have worked on more recent rail projects focused on train and passenger connectivity.
For now, we suggest, we shouldn’t reinvent the wheel. Thus Real Wireless has developed a strategy to manage wireless connectivity along rail transport corridors – one that recognises present-day reality and works with it.
First of all we set performance KPIs and define relevant technical parameters. Then we look at budget constraints. Armed with available data on the environment and available infrastructure, plus our own planning tools, we set realistic coverage and performance targets.
The signal blocking of the train’s body is a challenge, but there is theoretically a straightforward solution: it could be overcome by an external antenna on the train-top, connected to an onboard gateway. In absence of this approach, the signal level requirement – to overcome these blocking effects – increases, leading to an increased network density requirement and therefore higher cost.
Next we analyse existing coverage and try to answer some key questions – such as: Where are the not-spots? Where is the network infrastructure? Which existing infrastructure could be used to improve coverage and address blackspots in the most cost efficient way?
If the use of existing infrastructure does the job, then the job is done. Otherwise the next step is to determine the ideal infill sites locations to address remaining notspots and achieve the coverage or performance targets. With the current approach to rail connectivity, multiple operators – and therefore sites – will be involved in this process. Though the MNOs site sharing approach (based on JOTS Rail) or multi-operator neutral hosting may eventually ease this problem. Then we look at the overall route improvement statistics for all parties. What is the best approach for all MNOs to achieve maximum coverage in the most cost efficient way?
Unlike the early days of passenger rail connectivity 20 years ago, demand will not be just for voice and text services; the exponentially growing data demand has to be taken into account as well. Todays higher data rate requirements will require more sites and spectrum than what was needed for uninterrupted voice coverage. We therefore look at the voice/data trade-off and assess what is feasible – again with an eye to budgetary constraints.
There may be some useful bonuses to this strategy. Added trackside infrastructure will improve coverage for local end users as well as end users on passing trains. For example fixed wireless access for nearby houses and factories could be a source of extra revenue.
For the moment, we believe that targeting coverage gaps using available infrastructure and infill sites is the appropriate strategy for rail connectivity. Finding the right balance between capacity offering and cost is an important consideration, typically the higher the capacity aspirations, the higher the cost.
We also know that this takes high levels of engineering, planning, economics and mathematical expertise – expertise that, unlike many wireless consultancies, we have proved we can offer. This is why we were invited by the MNOs to contribute to the Joint Operator Technical Specifications (JOTS) for the open route and tunnels.
We have proven that the involvement of our experts at an early stage saves money in the long term by optimising performance and reducing infrastructure spend. It’s a truism, but always worth emphasising, that seamless rail passenger connectivity can be an expensive exercise – if it’s not planned carefully.