Metros need reliable, high-performance communications to help them run smoothly. Yet nearly all metros today rely on outdated, disjointed communications networks. A case in point is Madrid Metro, the 8th longest metro system in the world, carrying 560 million passengers a year.
Metros typically use separate radio access networks, based on proprietary or standard Wi-Fi. When train drivers need to talk to their control center, they use terrestrial trunked radio (TETRA), DMR technology, or another private mobile radio network. Passengers who need help in an emergency use the same system.
Managing these separate systems is difficult and inefficient. Most are narrowband, lacking the ability to use the data hungry apps and critical services that transportation companies now look to adopt.
“Is just one network possible?”
What if there could be just one, all-encompassing communications network that seamlessly supported all the voice and data services a metro could need?
This was a question Madrid Metro wanted to answer. It initiated a project called railNET, designed to upgrade its train-to-ground system to get more bandwidth and provide new services such as CCTV-HD.
The project had several goals in mind - to provide internet access for passengers via on-board and platform Wi-Fi access points and achieve high definition video both on trains and platforms. Keeping the trains running is, of course, essential and the network had to also carry maintenance data from trains to the control center. Voice over IP (VoIP) from train to ground and between trains was another ambition.
While looking for a partner to help it realize this vision, Madrid Metro turned to Nokia following its successful LTE trial for the Paris Metro. Working with several partners, Nokia managed the project, supplied the LTE technology, and was responsible for testing at its Transportation Solution Labs.
The Paris trial showed that the most critical applications, such as Communication Based Train Control (CBTC), could operate with no packet loss and lower latencies than conventional Wi-Fi technologies, even in metro tunnels.
Madrid Metro invited Nokia to run a Proof of Concept (PoC) project to see how an LTE based system would meet its needs. Step one was installing an LTE system based on its AirScale Wi-Fi controller and access points, AirFrame Servers, Flexi Base Stations and Compact Network LTE core. Several months of testing and development showed that the network could in fact provide everything Madrid Metro wanted.
The Madrid Metro PoC is the most sophisticated metro communications trial yet. A major success of the project was to aggregate two 20 MHz carriers to deliver up to 150 Mbps, and bring a high-quality mobile broadband service to passengers. Real time video of the train doors is also displayed on screens in front of the driver, boosting passenger safety.
Madrid Metro now has a clear track to drive its systems forward towards the latest mission-critical broadband technology and provide its customers with optimal service.
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