To keep Parisians and visitors flowing seamlessly, the RATP must keep its communications flowing seamlessly as well. It relies upon a fully integrated TETRA network from Cassidian to connect a total of 15 000 users across 1000 trains, 4500 buses and 300 stations. In addition, RATP now offers access to its TETRA network for use by other organizations.

Among RATP’s radio users is its security force, which employs the TETRA network for group calls, status and SDS messages and emergency calls. It also uses Dynamic Group Number Assignment (DGNA), which enables RATP to create unique user groups on-demand for special events or incidents.

One challenge in setting up RAPT’s network was to provide adequate underground coverage. In particular, the engineers had to share cables between different radio networks, manage planning and power budgets and enable successful handovers in the tunnels.

Sharing the benefits

Since 2004, when the first of the network’s 450 base stations was installed, RATP has developed its own expertise in designing, implementing and operating its fixed and radio communication systems. Now RATP is spreading the word about TETRA by offering its services to other organizations, such as the City of Paris, the municipal police forces of individual cities around Paris, plus a local transport company. Over the next few years, some 2000 to 5000 more users could be added to the network’s capacity.

Despite the diversity of organizations and users involved, security has never been a problem. Organizations can use the secure TETRA radio system without being overheard by anyone outside the network. In addition, the system’s full Virtual Private Network (VPN) functionality enables RATP and the other organizations to share the network without compromising each other’s privacy or security.

Opening up the TETRA radio network will improve RATP’s return on investment. The extra commercial revenues will help ensure long-term sustainability of what is now a strategic regional network.