Theory and Practice of Cognitive Radio

14.05.2012 11:32

Last week I attended a three day course at Aalborg university on cognitive radio. Cognitive radio research is the reason behind the development of spectrum sensing hardware for VESNA. Since I haven't encountered this field before joining the Jožef Stefan Institute I decided to go to this course to get some background and to better understand what is the state of the art in radio communications.

Aalborg university

It turns out cognitive radio means many things to many people. In the most broad sense it's an autonomous device that can optimally use the electromagnetic spectrum for communication by being aware and capable of adapting to its environment. This idea is then developed by some to an extreme, where the radio contains strong artificial intelligence that has perfect knowledge of its surroundings and is capable of predicting future events and the wishes of the user. For instance a mobile phone that learns your daily commute and plans ahead in cooperation with base stations on how to optimally use the cells on your way to the office. The personal digital assistant idea is strongly coupled with this and sometimes cognitive radio device is even described as being capable of communicating with the user through speech and natural language.

But such visions I only see as a thought experiment, as I can see no indications that such machines will be possible anytime soon. On the other hand however there is a more pragmatic approach to cognitive radio that concerns itself mostly with how to more efficiently use the limited amount of usable frequencies and overcome the spectrum crunch. This research covers for instance new ways to dynamically allocate frequency bands beyond very static licensing regulation that is in use now, how to enable secondary use of frequencies that are unused by people that initially licensed it for exclusive use and how to decentralize frequency allocation. It is also tightly connected to software defined radio technology that enables this kind of quick reconfigurability of radio devices.

USRPs, part of the ASGARD test bed at Aalborg university.

Besides lectures that covered information theory, networks, game theory, machine learning, software radio and economics we also had a practical demonstration of the ASGARD software radio platform. Guys from Aalborg university demonstrated three pairs of USRP devices that were dynamically and autonomously selecting radio channels in a shared 5 GHz ISM frequency band so that the interference between them was minimized.

The course concluded with a poster session where I also presented the spectrum sensing expansion for VESNA with the following poster (PDF version).

UHF spectrum sensing with VESNA, poster

Posted by Tomaž | Categories: Life

Comments

S51FF should be proud of your recent work! I am also. My first YU 16-bit PC made at IJS in 1984 is on display at GOTO1982 exibition in MNZ. I am working on Morse robot again, my unfinished PhD from 1991. Dull it isn't at 67!

73 de Mario, S56A

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