Channel Kidnapping for emergencies.

While police, fire and rescue services in Germany at the launch of the Tetra digital radio authorities wait for researchers already working in the communications networks of the future: channel find, use and quickly beat it - this is the future.

 

Communication is an important weapon against the chaos in the event of a disaster. In large damage capacity radio equipment are scarce. Not infrequently obstruct reporters and concerned citizens of the mobile phone with them. Equally, the technical infrastructure is damaged, as in the Italian earthquake zone, where radio amateurs helped to establish contact with isolated villages maintain.

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In this context, the thesis of Qiwei Zhang of the University of Twente in the Netherlands on progress in the development of a "cognitive radio" that this could solve many problems. Zhang researched methods to free radio frequencies in the event of a disaster at fitting to take, without the actual spectrum users disrupted.

With the channel as a function Kidnapping principle include depleted capacity for voice and data of the past. Better still: The proposed radio system consists of individual forms on the radio frequencies hijacked an ad hoc network and thus is no longer on a fixed infrastructure.

Tetra radio: Better, but not optimal

On the set in Germany's civil and security authorities. Although the increases currently under construction Tetra digital radio for public authorities and organizations with security tasks, the voice transmission capacity. It solves the problems but not completely and creates elsewhere even new, as Bernhard resin, radio expert of the Berlin Fire Department reported. "The rescue work of the new Tetra portable radios in direct fashion," explains resin.

If hot, the devices communicate there as traditional walkie-talkies with one another, without even the powerful Tetra network access. The advantage is that the communication in the closest vicinity to work. The downside: Direct Mode Operation (DMO) has only a range of several hundred meters. The advantages for communication and coordination, the Tetra radio actually offer to represent so precisely in the worst case on the spot.

But otherwise it's not, you need the salve DMO, because it is missing in Germany at the appropriate coverage. Tetra radio transponder is instructed, just as cell phones. If not in range or for other reasons can not be reached, the salve DMO - if it is seriously threatened again the bottleneck. In addition, existing analog building in the digital radio does not work anymore and the transmission rate for data applications with three kilobits per second sparse fails.

"It would be fabulous if the fire department its own wireless network could bring the same", will resin.

Pure flexibility: the response to frequency congestion

In the Netherlands, sparks police, fire and rescue services already using the Tetra technology, nonetheless began the "Twente Institute for Wireless and Mobile Communications BV of exactly those reasons four years ago, the communication of forces to fundamentally rethink.

"There were experiences from the devastating explosion disaster in Enschede in 2000 and the terrorist attack of September 11, 2001 in New York, we have shown that it is not enough to rely on the authorities and the mobile radio network to leave," says CEO Hugo Institut de Graaf. Unfortunately, there are in the lower frequency with which a good building supply and range could be achieved, no more seats. "That's why we have with the idea of radio addresses Congnitive. With a view over time it can be noted that only 6 percent of the interesting frequency range is actually occupied."

Cognitive radio will start exactly there: By the spot itself each frequency space searches. Application focus of the new technique is a powerful data within the framework of the international borders easily assistance and technical system boundaries can be overcome.

For the Echteinsatz the technology would have the frequency regulators internationally, however, already use the assigned radio channels allow: Cognitive radio, if you will, a kind of piggyback concept. This requires rethinking. An EU-level working group has been an emphasis on the importance of cognitive communication does not come out.

The industry-oriented research in Twente needs exploitable results, however: "We have some functional principles of cognitive radios, and build this' intelligence 'now in wireless terminals, which both GSM as well as WiMAX could be up," proclaimed Hugo de Graaf. Such radios can be an ad hoc network and will be presented this year on the market. "This is not the Cognitive Radio in its pure form," says de Graaf, "but at least times a useful start."