LTE if possible, TETRA if it must

According to Rohill, specialist in mission-critical communications, TETRA will continue to prove itself during the coming decennia. “TETRA is the emergency shoulder of the communication highway.”
People love contradistinctions. Contradistinctions see to it that people maintain their attention somewhere; a calm beginning of a song, which suddenly turns into a wave of sound, or the hard modernist lines as opposed to the romantic of a pointillist painting. Or – something less fairy tale like – the hard peanut covered in soft chocolate.

There is a new contrast in the last years in the discipline of mission critical communication: LTE as replacement for TETRA. A nonsense discussion, presumes Bert Bouwers, CTO at Rohill. “LTE and TETRA have never been and are not competitive technologies.” Bouwers initially emphasizes that there are no technological contradictions. “Take a look at the basic technology. LTE is entirely based on packet-switching for the transport of data of all services, including speech. The most important (technical) objective of LTE is a significant increase of the speed of data. The peak speed of data runs towards 100 Mbit/s on the downlink and towards 20 Mbit/s on the uplink in a radio channel with a width of 20 MHz.’’

In order to process the higher speeds of data in the radio network, it is also necessary to enhance the UMTS core network. This is named the UMTS SAE (System Architecture Evolution). UMTS SAE yields a new architecture for the core network that can be cost-efficiently built and maintained. UMTS SAE is optimized for IP services. This must make it possible to offer to the mass market the possibility of gaining broadband mobile access to IP services. SAE also allows to integrate the UMTS network with other access networks such as RLANs.

TETRA is an abbreviation of Terrestrial Trunked Radio. TETRA is a digital standard for radio communication that is mostly used by professional users such as the police and security services, public transportation, industrial users, or the army. TETRA is an official standard set up by the European Telecommunication and Standardization Institute (ETSI). “The advantages for the users are obvious. TETRA offers ultrafast call set-up times. Besides, the features of a TETRA network are highly suitable for emergency situations. The users are consistently capable of carrying out their communications. With other technologies, there is a tendency during emergency situations that communications is blocked because of the massive calls taking place in one area.”

Essential
“There are no contradistinctions’, Bid Manager Filtjer Wiltjer supports the argument. “Better, you can see this as supplementary techniques that come together.’’ LTE has as predecessor 3G (UMTS), 2G (GPRS), both as data overlay-network of GSM, (maybe you can also call Mobitex 1G). TETRA comes from MPT-1327 and proprietary PMR trunking solutions, and for ‘enhanced data’ TEDS has been developed.

In the roadmaps for TETRA, people have been considering for a long time the option of using TEDS (a component of TETRA 2), but there has been little progression. TEDS in the meanwhile, in terms of technology, has been caught up. Wiltjer: “According to us, TEDS never came into the picture. However, TETRA remains essential for voice-communication. The need for broadband data is then additional and the demand for it will definitely increase. LTE can be deployed as an ‘overlay’ network. The challenge is that LTE cannot be deployed as a mission critical solution. Maybe in a densely populated and crowded area a private LTE network may be deployed, but, in rural areas, how many masts do you then need?’’ Another challenge is that of owning a dedicated LTE network. Large investments are made by commercial operators. The government can of course place its own masts, but no single government will want to pay the costs. Can you then reserve dedicated spectrum for mission critical communication onto public networks? “You don’t want to start with that,’’ says Wiltjer. You should be able to trust a network and you can’t do that if you don’t have control over the network. If you want mission-critical communication, you can’t go to LTE. And that for at least 8 years.”

Forefront
Bert Bouwers also sees aspects that are applicable to TETRA and not to LTE. “Many companies inside the TETRA + Critical Communications Association (TCCA) are working hard to offer specific characteristics of TETRA, also via LTE. DMO, group communications, and Push-to-Talk are insufficiently developed. These are critical services which are needed in a mission-critical environment.” What does, according to Bouwers, the applications for LTE look like in the near future? “Services can just make use of LTE networks. There’s nothing wrong with that. But when the need is for real mission critical communication, TETRA has developed itself for a decade to be the most trusted and most feature rich solution for mission-critical communications. LTE if possible, TETRA if it must. And no, I fear that TEDS cannot play a single role.

Which technology can become important? “Rohill has a position in the forefront of international developments in the communication domain,“ says Bouwers. “Take SALUS, for instance. SALUS is a European funded project to further develop mission critical communication scenarios and products – offering both speech and data – on basis of broadband LTE. We are working together on this European project with Alcatel-Lucent, Cassidian (has meanwhile become Airbus), Airwave, the University of Twente and the Twente Institute for Wireless and Mobile Communications. We are cooperating with working groups within the CCGB.“ CCGB stands for Critical Communications Broadband Group, a part of TCCA . “We are working on the future applications. At present it is possible to use 3G and 4G for day-to-day operations, for example to transfer video or access backoffice systems . But how do you prepare yourself for a football tournament? And finally, what is the organization like if a spontaneous disaster takes place? We are working on these scenarios together with our SALUS partners. We believe the future of TETRA is that these become integrated with the future LTE solutions. TETRA is the emergency shoulder that must always be free and accessible.”