Rohill, the Dutch trunked radio specialist, demonstrated an innovative base station interface (BSI) which enables operators of MPT networks – and their subscribers – to migrate progressively and painlessly to TETRA. On Rohill’s exhibition stand to discuss it was a pioneer user – Michael Eberhardt, of Antec Funksysteme, who runs a commercial trunked network in Nuremberg, Germany.

“What we have new in the Rohill system is the TEP BSI interface”, he said. “With this base station interface system we can connect directly the transceiver of an MPT 1327 network. We are able to make a real soft migration from analogue MPT to TETRA.”

“It’s a fully seamless integration”, echoed Oliver Werning, Rohill’s business development director. “The clients still use their numbering plan, they still use their terminals and can be reached through the TETRA radio and vice versa. So basically the user does not see, feel or smell anything. They can talk!?”

Managing the users

For a service provider such as Mr Eberhardt, migrating from analogue to digital generates two problems. “Everybody who has an analogue MPT network like me has a running system”, he explained. “So the first problem is I don’t want to throw away the parts of the system, because they are working, and to buy a new transceiver, because I have transceivers.

“The second problem is when you go to a customer as a provider, you have to say, ‘OK, now we have TETRA and we are able to give you the TETRA infrastructure’.

“So he says: ‘Why should I buy new radios? The old analogue MPT radios are still working; why should I buy new ones? You have to give them to me for a present and then I will take it!’

“But in this case, I don’t have to change the radios of the customer. He can use his analogue radios and I only change the radios which are damaged – or when he buys a new one, I can sell him TETRA radios. And so he is able to communicate in the same fleet, in the same group – TETRA, analogue MPT, whatever he likes.”

In Antec’s Nuremberg installation, the whole network is now controlled by a Rohill TETRA switch. The TEP BSI unit interfaces this via a four-wire connection to the existing analogue base station, which is an MPT unit by Rohde & Schwarz. And the dual network has been running for months without problems.

Technology-independent

“In our system, we have a soft switch architecture which means the switch is an application”, Oliver Werning added. “Once we have a soft switch architecture, it is technology-independent. It can switch MPT, it can switch DMR, and in theory APCO, LTE or whatever. This is a unique solution we have here right now, and this is really unique also in the TETRA world.”