“In terms of handovers”, he continued, “the use of onboard repeaters facilitates the usage of elongated cells that reduce the number of handovers required. Handovers required inside long tunnels need extra care in order to create adequate crossover areas between two cells in order to maintain service continuity.”

For Wi-Fi systems using satellite as a backhaul connection, one method of overcoming loss of connectivity while the train is inside a long tunnel is to use a powerful onboard server with a large cache memory to store several pages of the most widely accessed web sites.

For its part, CommScope has delivered onboard coverage solutions based on its NodeAM mobile repeater solution and radiating cables. This equipment has been deployed by customers in numerous countries, including the new high-speed Frecciarossa and Frecciargento fleet in Italy. CommScope has also deployed solutions for train operators in Switzerland, Finland, Denmark, Sweden, Austria and elsewhere. 

Broadband beneath the city’s streets

A ground-to-train data transmission system for driverless operation is part of a broadband communications upgrade supplied by Alcatel-Lucent for the Paris Metro’s busiest line. Serving major tourist destinations such as the Louvre Museum, Line 1 links Château de Vincennes in the southeast with the business district of La Défense, carrying an average of 725?000 passengers daily.

Through a collaboration with Alcatel-Lucent and the public transport operator RATP Group, Line 1 is now benefiting from real-time video train control, video surveillance and operational data transfer between trains and the control centre. The scheme has been a key part of RATP’s project to transform the line into a fully-automated, driverless system.

Real-time data

The ground-to-train data system (Transmission de Données Sol Train, TDST) allows real-time monitoring of the flow of data between the driverless trains and central control. Twin cameras at the front and back of each train provide real-time video for the control centre, while surveillance images streamed from cameras within each carriage enhance passenger security.

Alcatel-Lucent’s system includes the provision of passenger information services, including on-board TV, advertising and updates for travellers and visitors to the city. In addition, TDST provides rapid notification of maintenance needs, reducing response and repair times and improving the efficiency of the service.

A smooth implementation of the TDST system by Alcatel-Lucent enabled the transition to driverless operation to be completed without interruption to service on the line.