Extra terrestrial

TETRA’s continued advancement and improvement is increasingly meeting the needs of traditional mobile radio user organisations. TETRA Association’s Chairman Phil Godfrey tells EU Infrastructure how the standard bearer for the industry is looking to expand its services.

“TETRA is a digital technology, and therefore all of the voice that goes from one user to another user is already digitised. So to add encryption in itself is not that difficult.”
-Phil Godfrey

EU Infrastructure. The TETRA World Congress 2010 took place in May in Singapore. What made you decide to hold the event there?

Phil Godfrey. Well, traditionally we used to hold the event in various parts of Europe, but TETRA has become a global standard so we felt that it was appropriate to not expect everybody to want to come to Europe, and the Asia Pacific region is the fastest-growing region and probably has the greatest potential still. So two years ago we decided to go to Asia and we went to Hong Kong, which was a very successful event. Then we were back in Munich last year, and then decided it was appropriate to go back to Asia this year.

EU. You are in Budapest next year. Is it something that you will look to alternate between Europe and Asia?

PG. That is what seems to have happened in the last few years.  There are various pressures to go elsewhere, particularly South America or even Central America. We have also been trying for some time to open up the North American continent. We have had various meetings with both the Federal Communications Commission, the FCC in the U.S., and also their equivalent, which is Industry Canada in Canada. And the FCC invited us to demonstrate, but part of the problem is that because TETRA packs an awful lot of information into a single 25 kHz channel, it actually exceeds their current analogue emission mask by a very small margin.

That does not imply that it is more likely to cause interference, it is just that they still use a mask that a transmitter has to fit inside of, which was originally developed for the old 25 kHz analogue radios. So in North America they recognise that the steeper sides of TETRA make it a good neighbour to other technologies and invited us to apply for a waiver. We actually had a meeting with the FCC in May to see what progress was being made. It is taking longer than we had hoped but they still seem quite positive.

EU. How has the TETRA technology - particularly TEDS (Tetra Enhanced Data Service) - matured and evolved?

PG. A number of years ago we decided that we needed to make sure that TETRA remains an up-to-date technology, and so we had a working group to look at what enhancements were needed to the standard to make sure that it was good for the future. That working group came up with a number of items that were fed into ETSI, and they did the standardisation work to standardise those enhancements. Range extension was considered an important item, particularly for air to ground use, because transmissions obviously go a lot further from airborne equipment, and so range extension was one new codex or sound device.  But the most important was an enhanced data service.

If you go back to when TETRA was originally specified, which was back in the early 1990s, if you were lucky your landline modem would give you a speed of 14.4kbs.  It sounds ridiculous in today's age of super-fast broadband, but that actually was the case. And so at 28.8kbs we classed TETRA as high-speed data; but that of course has been long since overtaken. We came up with a suite of standards for producing a higher speed data rate depending on the modulation scheme that you use and also the channel bandwidth that you use. But TED specifies anything up to about 600kbs, while the most popular in a 50 kHz channel will give you about 150kbs. With that you can actually do quite a lot, including accessing online databases and even a certain amount of video.

EU. Tell us more about TETRA's video capabilities.

PG. It is obviously not catering for high-speed streaming, but it depends on what you want to send.  For example, if you have a police control centre that has a reported little girl lost and they want to send a photograph out to everybody's handset, then obviously, this can be done using TETRA release 1, but you can do it a lot quicker with TED.

This standardisation work was completed two and a half years ago. Just before the World Congress, EADS announced that they delivered TEDs products to the Finnish police, and they were in the process of going through acceptance testing of those.  Also during the World Congress Motorola launched their TEDs products. So we were really pleased - having talked about TEDs for quite a long time - see actual products fit in the market.

EU. What makes TETRA so reliable and important for mission-critical users like the police force?

PG. TETRA is a technology that was designed specifically for people in working groups who, therefore, need to communicate in groups. That sets it apart from any of the cellular technologies: 1G, 2G, 3G, and even 4G, which are all based around the principle of-person-to-person calling or accessing data from a single point. TETRA is quite specifically designed for people who work in groups. The reason that TETRA is quite a complex technology is because the mobility management of tracking fleets of people across what can be a nationwide infrastructure is complicated: if somebody makes a call to his home group and two or three people have gone over to the other side of the country, they can still be included in that group, but in an efficient manner. In other words, you don't light up the entire country's transmitters to make that call. This is actually quite a complex process to do - to track the people, know where they are, know whether they should or should not be included in a particular call etc. 

EU. Is TETRA unique in this respect?

PG. There are very few technologies that are designed specifically to do this.  TETRA is one.  There was a French-developed technology that became known as TETRAPOL - which has nothing to do with TETRA - for the police; they were obviously jumping in on the name. Then there's Project 25 in the U.S.; there are one or two other proprietary technologies, but Project 25 was designed more towards low-capacity systems operating over large areas. If you consider the geography of the U.S. you can understand why they have optimised it in that way.

TETRA is designed more for high-capacity networks with high functionality and has become the standard worldwide.

EU. How important is TETRA's reliability in overload situations?

PG. Very. If you compare TETRA with cellular technologies, and if you take something like the London bombings, the first thing that happens is everybody jumps on to their mobile phone to call home and say, "I'm all right."  The networks cannot cope with that sort of demand; they are not sized for it and they are not designed for it and so the networks either collapse, or in some cases they are actually switched off for security reasons, because some people trigger bombs using mobile phones.

The TETRA networks for mission critical users are specified and designed to cope with peak loads of traffic, and they have priority mechanisms and graceful fallback mechanisms that are designed specifically to cope with very high peak demand.

EU. How is Europe utilising TETRA in cross-border interoperability?

PG. The TETRA release 1 included within its specification an interface called the intersystem interface, which was really designed to enable cross-border working. In particular in the public safety circles in the very early days there was a telecommunications group as part of the Schengen agreement, who were given the task of making sure that when the physical borders came down in Europe, policemen chasing criminals could drive across borders and continue to work, making sure that networks were capable of being connected together to provide that level of cross-border working, and that specification was called the intersystem interface.

It has actually been rather slow in coming to market. In the early days of TETRA the manufacturers were under a lot of pressure to get the core technology out and to keep introducing more and more of the functionality. So the intersystem interface tended to get overlooked. However, a lot of the national public safety agencies are now pressing for this.

EU. As TETRA expands into new markets, how challenging is the issue of interoperability?

PG. The new markets have been a bit more forward in demanding the technology. But this is made more difficult by the fact that different manufacturers have different architectures for their networks. The two main manufacturers of infrastructure are EADS and Motorola, so it is getting those two to work together that has been probably the biggest challenge, because their networks are completely different. They have been working together; they've been making some progress, although admittedly it has been a bit slow.

EADS has the contract to supply infrastructure for Germany and also for Sweden, so they have continued to work on the intersystem interface and have managed to get that working between their own networks.  So they are two completely independent national networks, but they're both EADS, which makes it slightly easier. 

EU. How do you ensure that neither security nor interoperability is compromised?

PG. Security is an extremely important subject. Within the TETRA Association we have a special group called the Security and Fraud Prevention Group that is specifically responsible for all aspects of security over TETRA networks. They handle all of the encryption issues and most police networks, and probably most public safety network that include a certain amount of encryption.

There are various types of encryption; you can encrypt just the air interface so that nobody listening in with a scanner would be able to understand anything, even if they have a TETRA decoder. But many organisations feel that that does not give them enough protection, because somebody in the telephone exchange could tap into the landline feed and pick off the conversations there. So for those that feel they need additional levels of security, they will implement something called end-to-end encryption, which means that the link from one user to the other user is fully encrypted all the way, regardless of how many switches it goes through. TETRA is a digital technology, and therefore all of the voice that goes from one user to another user is already digitised. So to add encryption in itself is not that difficult; it does not slow down the messages - all you do is scramble up the bits before you transmit them and then unscramble them on the other end.

The most important thing is managing the encryption keys. You need to change them regularly; you need to make sure that only the right people are allowed to get access to those keys.  And there are strategies for doing that, and the Security and Fraud Prevention Group covers this as part of their role.

EU. What steps are you taking to ensure that TETRA remains relevant in the future?

PG. The next step is where what has colloquially become known as TETRA release 3 comes in. We effectively asked our users, "Okay, guys, what is it you're going to need for the future?" That was actually quite a difficult task, because many of the public safety users in particular are still trying to cope with the level of functionality that they've recently been given. 

If you think back over the years, most public safety agencies have been working with open channel, "Can you hear me, Charlie? Over" radios. And now that they have the levels of functionality that TETRA gives them, they can have the ability to create different groups and dynamic groups, so they are now asking us, "Right, now that we're no longer limited in our procedures by the limitations of the communications network, let's go back and see how we can make most efficient use of our personnel by modifying or configuring the network accordingly."

But the clear response that has come back from users is that everything is going data: the ability to have officers filling in reports on the street, the ability for them to query databases, access images and all that sort of thing is clearly going to be an advantage to us, and therefore we need a higher-speed data than we have currently. So the next challenge for our engineers is mobile broadband. We are looking at some of the available technologies, such as WiMAX and LTE, to see whether or not those technologies could form the basis of a third generation of TETRA or whether they are too far adrift and we would be better starting with a clean sheet of paper. 

Clearly we do not want to reinvent the wheel, but sometimes it is actually easier to do that than to make major modifications to another technology.

  

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Biography

Phil Godfrey
Chairman
TETRA Association

Phil Godfrey is the Chairman of the TETRA Association. He has been in the mobile radio industry for over thirty years with Pye, Philips and finally Simoco where he became Market Development Director. Phil was one of the founding members of the TETRA Association back in 1994 and has been instrumental in developing the standard into a globally recognised technology. In addition to his role with the TETRA Association Phil also runs his own consulting business.