Cognitive Radio – Adaptive Technology Panacea or Complexity Just Because We Can?

Cognitive Radio, being much discussed, is a computer driven adaptive technology often defined as “networks are sufficiently computationally intelligent about radio resources and related computer-to-computer communications to detect user communications needs as a function of use context, and to provide radio resources and wireless services most appropriate to those needs.”

More simply put, Net & Radio resources that evaluate, an then adapt method-mode-frequency-priority-sequncing, all based both evaluation of the original message and the technology & environmental opportunities to communicate the message.

Commercial/Governmental/Military have long used varying evaluative systems, though often hybrid manual/computer, to handle traffic with some of the decision tree that goes into Cognitive Radio systems.

How Useful would Cognitive Radio Systems (CRS) be for Amateur Radio? Other than experimentation Amateur Radio tends to not have the repetitive hierarchical traffic that is the best fit for CRS. Perhaps in the Emcom mode there is some utility, but more likely under a RACES type structure than a normal amateur use.

One wonders if CRS are warranted, or Just Complexity Because We Can? Just a digital SSB has a small place, but doesn’t seem currently a candidate to replace analogue SSB on a large scale, CRS is interesting, but lacks amateur utility.

That the frequency hopping runs afoul of the FCC rules for Amateur Radio HF Bands may be a problem.

Does the user loose control or is it an aid? Many who have experienced a major CRS communications environment recognize what this question is about – will your traffic authenticate and be moved, be “bumped” by higher priority traffic, or be shut off? CRS designs very strictly control the traffic that is passed in a way that is not typical for Amateur Radio. We may refuse certain passed traffic over content, third party rules or for other very limited reasons, but there is no “Control” like CRS where traffic can be manipulated or deleted.

I should be clear that there are many different concepts of CRS, some that are more technical (TETRA and other cell/near-cell ideas), some that are adaptive within fairly tight confines, and a pure theoretical CRS idea of being fully adaptive on every possible axis.

While there are likely fortunes and fates at stake in the serious use of CRS, for the present Amateur Radio community it looks of limited utility – an ideal experimentation area, but not a paradigm shift for the hobby as a whole.



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3 thoughts on “Cognitive Radio – Adaptive Technology Panacea or Complexity Just Because We Can?

  1. Hermann Schumacher, DF2DR says:

    The use of Cognitive Radio techniques for hams is an interesting issue and I agree with Steve that it may be attractive for its experimental value, not as a standard technique or even “the” new paradigm of ham radio.

    Radio hams could still contribute in a very meaningful way to the development of the technology. Reviewing the scientific literature on this topic, one finds that while much has been done on the networking aspects, there is precious little work on what many hams will easily recognize as a major challenge – frontends which allow rapid spectrum sensing with a sufficiently large dynamic range. Frontend design and dynamic range issues is something that hams frequently know a lot about.

    We recently performed our first real world long-term spectrum assessments here in Ulm between 300 MHz and 3 GHz, and it is indeed interesting how much spectrum is, while allocated, permanently unused. So the fundamental hypothesis of cognitive radio is valid.

    TETRA, by the way, would not qualify as cognitive radio. It is a trunking system where the terminals have no cognitive capabilities, nor does the network, which assigns channels assisted by databases, not by assessing spectral occupation.

  2. k9zw says:

    Hermann DF2DR is so very correct on both how much allocated spectrum remains unused, and in my mixing TETRA into the discussion.

    Wondering if the spectrum assessment study is repeatable by a group of amateurs in a location?

    The definition of Cognitive Radio is a bit elastic, and having heard TETRA (“Trans European Trunked RAdio” – since updated to “TErrestrial Trunked RAdio”) described as a sort of “Cognitive/Intelligent-Adaptive System” I had brought it into the discussion. It is quite different than full classic “Cognitive Radio” and perhaps is one of the better known standards of an emerging class of enhanced adaptive systems.

    The reminder that basics – dynamic range and front-end design – remain areas for advancement shouldn’t escape the amateur’s notice – these potentially offer huge rewards for effective advancement of the state of the art of wireless!

    Thank you for your thoughts and perhaps we could learn more about the spectrum study?



  3. Hermann Schumacher, DF2DR says:

    TETRA is quite similar to GSM in its structure, its concepts date back to the mid-nineties – it just took a while to gain widespread acceptance.

    As for the spectrum studies – we simply used a wideband antenna, a standard Agilent spectrum analyzer and a computer program written by one of my students which takes periodic sweeps over a period of time (up to one week in our case), and stores it. It then allows to run different analyses on the data. This can easily be reproduced also be a well-equipped ham.

    An interesting alternative, which we are also planning to pursue, would be to use one of the new direct sampling software-defined radios as a wideband IF spectrum analyzer behind a wideband downconverter. It would take a, say, 60 MHz wide spectral snapshot, then step the downconverter by 60 MHz, take another snapshot and so forth.

    Apart from finding unused parts of the spectrum, our goal at the moment is to gain statistical information on real-world dynamic range in the 300-3 GHz frequency range. The location of our building, on top of a hill about 1800 feet high (we are Germany’s top university in feet above sea level) with a clear shot towards the Alps over 60 miles south of here makes this a quite ideal location. The data will then be used to develop specifications for a wideband high-linearity frontend for spectrum-sensing radio.

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