ALCATEL-Lucent began testing Long-Term Evolution (LTE) wireless broadband on Paris Metro Line 14 in June, following several years of research and development. The test is unique because it is the first time that signalling will be tested using LTE in regular service, and forms part of the Telecom System for Future Urban Transport (Systuf) project.
Although GSM-R is likely to remain the backbone of railway communications into the 2020s, Alcatel-Lucent maintains that LTE should be considered the next generation system of ground-to-train voice and data communications for urban and main line railways.
"LTE will cost less money to metro operators and provide new services to passengers," says Mr Thierry Sens, marketing director of transport at Alcatel-Lucent.
The benefit that LTE could bring to the rail industry, according to Alcatel-Lucent, is its ability to consolidate the delivery of multi-service traffic on a single ultra-broadband radio network, currently delivered through a fragmented system of legacy wireless networks. But until now, signalling in LTE has remained untested.
"We know that LTE is best for broadband and Professional Mobile Radio (PMR) but we don't know about signalling in LTE; the purpose of the trial is to test what we will get," says Sens.
Research at Alcatel-Lucent's Transportation Laboratories has sought to extend 4G to onboard coverage for passenger services by deploying small-cell technology inside the trains. Meanwhile, Alcatel-Lucent's research subsidiary, Bell Labs embarked on a sister project in 2012 to study special adaptions of LTE microcells.
"We're nearing a breakthrough in microcell technology that would enable the provision of 4G services in trains," Sens says. "LTE would form the backbone of those services." A number of different scenarios will be tested on Paris Metro Line 14 between Olympiades and Bibliothéque - including testing components individually, at the same time, and at different train speeds.
"Part of the test on Line 14 is stressing the LTE network with extra traffic to see if the signalling is okay or not in LTE," says Mr Jean François Ripouteau, project management director with Alcatel-Lucent.
"We will be monitoring to see if critical applications are still working properly. It is very important for mission-critical applications like signalling to be permanently on - even in extreme radio coverage conditions and when the train is running at full speed," he continued.
"The challenge of testing on a metro is that it is not easy to mobilise resources - especially the train during peak hours," Ripouteau says. "So we agreed with the Systuf consortium that we'd conduct the testing mainly outside of heavy traffic hours - with some testing in traffic hours - but not in heavy traffic."
Spectrum
The LTE technology has been integrated in the on-board unit (OBU) supporting the signalling applications. The OBU is called Netbox and is supplied by Alstom, one of the eight members of the Systuf consortium. But the commercial deployment of an LTE network for metro operators is not without its complications. Most European metros do not have the spectrum to deploy such a network and Sens says that it may take a few years to resolve the issue.
"If the trial is successful the Paris metro would certainly like to deploy it for future metro line projects, so they're lobbying to get the spectrum," Sens says."This is not only a problem for the Paris metro, but also for the police, public safety agencies and all entities owning critical national infrastructure."
The Systuf consortium has eight project partners, including RATP, Eurecom, Télécom Bretagne, Simpulse, Ifsttar, and Mitsubishi Electric R&D Centre Europe (Merce). The goal of the project, funded by the French National Fund for a Digital Society (FSN), is to demonstrate the feasibility of using a single communication technology based on LTE to simultaneously meet the requirements of critical and non-critical applications, and to enable the development of services that meet the demand for 'smart and environmentally-friendly mobility.'
