Underground and overground; the evolution of rail and mobile coverage

The rail environment is unlike any other environment when it comes to mobile coverage, and there are so many facets to the type of rail coverage available – onboard coverage, tunnel coverage and trackside communication for example – it can be a confusing landscape to navigate.

Why is rail and train coverage important?
Getting coverage inside high-speed trains, as well as providing coverage at train stations and on underground metro systems is a given in today’s connected world. For the passenger, they are able to make better use of their time while travelling, often incorporating their commute into their working day. They can continue to connect with the outside world through voice calls, texts and emails without the signal dropping out constantly or sometimes not being able to get a signal at all.

For the mobile operators involved, they are likely to achieve a higher customer satisfaction score due to the continuous network availability, whether they are waiting at a station, or actually travelling on a train itself. Dropped calls or the inability to connect will always be blamed on the operator first and foremost by its customers! As well as continued customer contentment, the extra coverage brings with it increased revenue with premium, standard and roaming customers as they continue to download data as long as they have a connection.

For the rail network operator, in the case of onboard coverage, they too receive greater levels of customer satisfaction as their passengers cannot differentiate between their coverage on the train and off it. As a result it contributes to a better utilization of rail services overall and is not seen as a barrier to this method of transportation as it perhaps has been in the past. The ability to connect also extends to the emergency services, which means increased levels of passenger and staff safety.

OnBoard coverage
By providing onboard coverage inside high-speed trains the passengers receive an improved travel experience. A simple onboard coverage network is made up of a roof antenna that connects to the macro network outside the train, an onboard digital remote unit that takes the signal and amplifies it, then redistributes it through a network of leaky feeder cable in the carriage itself (as shown here).

Underground and Overground Coverage

Coverage inside tunnels and metro systems
Tunnel and metro coverage is equally challenging and often involves both tunnel coverage between stations, as well as capacity distribution at the stations themselves. During peak hours there is huge demand on the network resulting in the need for a high-capacity system that can cope during these peak time slots.

As trains travel at high speeds through the tunnels the handover between coverage cells needs to be seamless. On top of this the tunnel and metro environment provides extra challenges such as lack of space for equipment, difficult installation conditions (often dark, dusty and hot) and finally the requirement to work around operational hours as many metro networks are in operation 24/7.

A challenging set of requirements
As you can see, the rail and train environment throws up many challenges that need to be dealt with by mobile operators, rail network operators, metro operators and tunnel owners alike. Successful case studies include the Brisbane Airport Link (Australia’s longest tunnel), the Eurotunnel that connects France and the UK and the onboard coverage provided by Vodafone on East Midlands Trains.

A supplier of coverage inside the rail and train environment needs to provide network equipment that can withstand these challenges. In the case of tunnels and metros, it needs to have a small footprint, enabling easy installation and upgrades, and needs to be able to withstand tough environmental conditions. In the case of onboard coverage, the equipment again needs to be small and compact enough to work inside a train carriage with space restrictions, as well as providing seamless mobile coverage to passengers.


Ingo_Blog Ingo Flömer
Product Manager, Cobham Wireless

Ingo is responsible for defining the product management strategy at Cobham Wireless. He has over 20 years experience in telecommunication, wireless and fixed line and is also an Advisory Board Member for several enterprises and research projects.
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