Press Review

DIGITAL HEADING

Richard LAMBLEY meets Hubert AZEMARD, president of the Tetrapol Forum

" LET THE USERS DECIDE "

While the Home office and Britain's police forces negotiate with Quadrant over the future of the Public Safety Radio Communications Project, from across the Channel the Tetrapol Forum has continued its efforts to secure formal recognition of the Tetrapol specification as a digital radio standard in parallel with ETSI's Tetra.

Having originated as a proprietary technology, Tetrapol reached the market earlier than Tetra, and it has now been chosen by 25 major organizations in 14 countries. " If you want to have figures, today that means we have up and running 500 000 square kilometres with roughly 150 000 users ", says Hubert Azémard. " So it has proved that the technology is fitting the needs of the users. And when you take the perspective of all the 25 networks, when they are all deployed, that will represent half a million users and investments which are around 2.5 billion euro.

Technical strengths, user support

" We have technical strengths, but we have also user strengths ", he continues. " I would say it was proved last year when, you will remember, we had a special event in France (the World Cup football tournament). The police people were very happy to show the strengths of this technology and how they use the technology in a real case - in a crisis case. " This technology is based on a specification which is open to anybody. You can access the specifications of all the interfaces on the Internet - these are the Tetrapol PAS (Publicly Available Specification). All manufacturers who are manufacturing Tetrapol products have the duty to build products in concordance with this specification. They are not obliged to develop everything - as in GSM. GSM is a huge amount of specifications, and manufacturers are not obliged to develop 100 per cent of the functionalities; users and operators are not obliged to take all the functionalities. But there is a big core which is 70 per cent, at least - and the rest you take or don't take.

Operational Needs

" What is interesting, especially for police forces everywhere in the world, is that they are not all working on the same model. So they have to have a technology which offers different functionalities, and they take the ones which fit with their requirements. They don't want to adapt their way of working to technologies - they want to have a technology which fits perfectly to their operational requirements. Companies that think they are going to force the police people to change their organization to adapt to a technology - I think they make a mistake. They don't know the market. " M. Azémard argues that Tetrapol's narrowband FDMA signal (12.5 or 10 Khz width, with an 8 kbit/s traffic channel) offers better range and sensitivity than TDMA systems (such as GSM or Tetra - see panel, left), and so is cheaper to build because fewer base stations are needed to serve a given area.

" We have a very good example : the police forces in the US decided to go on a digital technology five years ago. They looked at FDMA technology, TDMA technlogy, CDMA technology. And they said, " Between the three, the one which fits our needs is the FDMA technology ". So they chose an FDMA technology - and, in Tetrapol, we chose an FDMA technology.

" That doesn't mean that FDMA technology fits all the requirements of all the users. It has been clearly expressed in ETSI, for example, that two technologies, FDMA and TDMA, were necessary to cover all the PMR market. But the FDMA technology is clearly, for most of the security services, the best technology in terms of price-performance.

Unpleasant surprises ?

" FDMA is a technology which is very robust in terms of transmission. When you want to transmit data in a robust mode, if you want to be sure to have voice but also data, then FDMA is good. People who have this type of requirement - people who want to be sure to have the same coverage for dataas for voice - choose the FDMA technology.

" When they are in the police car, if they are at the edge of a cell and they are following a gangster in a car, they want to be able to type the car number and not only to be able to talk with other police. People say, " TDMA is marvellous - we can have 28.8 kilobits per second data ". It's true - but only for a distance of one kilometre. After one kilometre, you are off. So you can't design it for 2.4 kilobits, which is a little bit different. " People are designing networks for data at too high a speed for the total coverage, and then they lose the connection. I think the users have to take care of the real cases... otherwise they will have very big surprises.

" This is one of the main strengths of FDMA. TDMA technology, as GSM, has been designed for small cells and high density. FDMA is a technology which is totally adapted to very large cells, and perhaps lower traffic. These type of people, they don't need to have GSM traffic levels. But they need to have cheap systems, and the bigger the cell, the smaller is the network for national coverage.

" When you are investing in the network, you are not just investing in base stations - you are also investing in links, you have to pay for the buildings, the electricity, maintenance and so on. It's not just hardware, either : when you take all the costs for 10 years, that's perhaps Users don't just buy systems because we are nice - of course we are nice, but the technology is nice too. "

"A big mistake somewhere"

M. Azémard's colleague, Philippe Meleard of Matra Nortel Communications, interjects : " I made an interesting calculation. You know the budget for the PSRCP at the beginning, it was roughly Ł 1.5 - 1.8 billion. This is exactly the sum of all the Tetrapol networks in the world. We are not comparing exactly the same thing because PSRCP is a service contract for 15 years. But if you consider the size of the UK territory with the sum of all the territories covered by Tetrapol technology all over the world, there is a big mistake somewhere. " M. Azémard continues : " Another strenght is the possibility of simulcasting, for people who want to talk in groups of users over a very large area. With just a couple of frequencies, we simulcast and everything is synchronized. Which is very important, because sometimes frequencies are difficult to get. " Another strong point is encryption : this kind of system has been designed from the beginning for security reasons, so we have an encryption system which is end-to-end encrypted - it's not just radion encryption. So nobody can break into a base station and be able to listen in. ".

Real competition,

M. Azémard seems unwilling to be drawn into commenting on the legal battle between Matra and the Home Office in London over its choice of Tetra. But he adds : " If I have to say something of the UK, I think what I would like to see in the UK is real competition. You have this PSRCP network. " My real concern on that is I would like to have seen a real competition between technologies. From what I know, there was no real competition. I think, it's a pity, because I am sure that Tetrapol is a technology which is cheaper than the TDMA technology and we would like to prove it. And then, let the users decide. " But if you give the users one solution - just one - that's not the way we understand competition. Your country is a very open country with a lot of liberalization, a lot of competition - so why not competition for so huge an amount of money ? "

Rivals : Tetrapol And Tetra,

Both technologies are aimed at police and government users (although in Tetra, emphasis is placed on meeting the wider needs of PMR and trunked radio users in general). Yet despite the similarity of their names, the two systems have some important differences.

Tetra was created in an open standards-making process within ETSI, as a PMR standard to complement GSM. Like GSM, it is based on a TDMA (Time Division Multiple Access) air interface : with four time-slots on each radio carrier, it can support up to four voice channels on each base station transmitter, with a consequent saving in hardware costs. Users needing extra capacity - for data, video or full-duplex speech - may borrow additional time-slots if these are not in use. Tetrapol, on the other hand, was developped as a proprietary technology by Matra, with the backing of the French Government. It has an FDMA (Frequency Division Multiple Access) air interface, using a separate frequency for each speech or data channel. Its first two applications were for France's police forces : the Rubis network of the Gendarmerie and the Acropol network of the Police Nationale. Having won export successes with the system in Europe and outside, Matra has made the specification publicly available through the Tetrapol Forum, which is campaigning for its adoption by ETSI as a mobile telecoms standard alongside Tetra.

Although discussions continue, ETSI has rejected these approaches in accordance with its principle that it cannot make a new standard which competes with an existing one. However, the Tetrapol camp argues that its FDMA technology is complementary to Tetra, offering particular advantages in range, sensitivity and installation cost for large networks having a relatively low traffic density.

In France, Tetrapol is used by two national police forces, the capital's suburban railways and the naval base at Toulon. In Germany the system has been chosen by car makers Audi and BMW, by Hamburg's harbour, Frankfurt Airport, Berlin's buses and NATO's AWACS airbase at Geilenkirchen. Other Tetrapol networks for security forces are in the Czeh Republic, Slovakia, Romania, Spain and Switzerland. Two systems are in the Middle East, five have been ordered for South East Asia and there are two in central/south America.

Hubert Azémard, of the Tetrapol Forum, the manufacturers' group within the Tetrapol community. The Forum's 36 suppliers offer terminals, infrastructure, accessories and test equipment.

Tetrapol in outline : numerals in white denote relevant sections of the technical specification publicly available from the Tetrapol Forum Web site. As in a Tetra system, mobiles can communicate via the wide-area network infrastructure, via a simple repeater, or " back to back " in direct mode.

Extract from Land Mobile (English), February, 1999