Cognitive radio evolution
In a recent discussion in the LinkedIn Cognitive Radio group I showed my opinion on the gradual changes we are living:
In my opinion the change will happen gradually and it is not possible for the telecom operators to stop it. Several countries are studying the possibility of opening the white spaces in the tv-band for unlicensed use in a similar way to FCC's proposal. When this happens the value of the licensed spectrum will go down, since service providers will be able to use this virtually cost-free spectrum.
Other people showed some skepticism on how this would happen, given the huge investment by operators in the auctioned spectrum. I agree that the cognitive radio technology is not mature enough in order to allow unlicensed devices to operate in all the spectrum bands.
Related to this we can find a 2008's blog post in which Keith Nolan attempted to place the cognitive radio technology on a Gartner’s Hype Cycle. This cycle refers to the media coverage and expectations that every new technology goes through. Keith concludes that cognitive radio already had gone over the peak of inflated expectations and the expectations on it were going down. This may had happened with respect to the general media, since if we look at the number of technical papers published with the terms "cognitive radio" (source: Google Scholar) we can see that we are yet into a growing phase:
This agrees with the fact that in order to achieve the practical implementation and revenue-generating exploitation, well established theoretical fundamentals are required. Note that for comparison in this figure I also show the number of papers in a newer topic as it is "compressive sensing". Since this is a more general tool that can be used in multiple fields it will soon beat cognitive radio research effort.
The need of further research is shared by David Cleevely. While in a recent interview he showed an optimistic view on the evolution of cognitive radio he also stated that this will happen in a long-term basis:
In the long-term these new technology developments will open up even more opportunities
Similarly, Joseph Mitola III believes that certain challenges remain in order to allow the standarization of cognitive radio systems, such as the semantic description and reasoning of CR scenarios, interactions and elements.
While the use of tv bands for open spectrum access based on geolocation databases is imminent, the extension of this techniques to other bands of the spectrum will only happen in a long-term basis.