Reconfigurable Radio Systems (RRS) is a generic concept based on technologies such as Software Defined Radio (SDR) and Cognitive Radio (CR) whose systems exploit the capabilities of reconfigurable radio and networks for self-adaptation to a dynamically-changing environment with the aim of improving supply chain, equipment and spectrum utilization.
Global interest in RRS solutions is being fuelled by the rapidly-growing demand for wireless communications for a wide range of purposes. For example, today there are already more than 4 billion mobile phone users and estimates such as those of the Wireless World Research Forum suggest that by 2017 there will be 7 trillion wireless devices serving 7 billion users. To meet these expectations with the limited radio spectrum, more flexible ways to share radio networks and frequencies amongst multiple services and radio networks are needed – and RRS technologies offer the solution. At this regard there is particular interest worldwide for the so called "cognitive radio technologies".
Cognitive Radio is quite a new concept and could be said in short as a radio with learning capabilities, i.e. a radio able to obtain the knowledge of radio operational environment and adjust its operational parameters and protocols accordingly. It is clear that such an approach has got undoubtedly a lot of benefits in terms of spectrum efficiency and this is much more important when the spectrum is scarce, as it is the case nowadays. Thus, there is great interest in Cognitive Radio technologies at European level as well as worldwide. One case study on cognitive technologies is in the use of so-called ‘white spaces' in the UHF band. White Space is unused spectrum at a given time and location, on a non-interfering/non protected basis with regard to primary services The application of cognitive technologies in White Spaces in the UHF broadcast band (470-790 MHz) is currently under study in Europe. Also other frequency bands which are "under-allocated" are of interest.
Public safety has a very limited frequency allocation: the only harmonized public safety band in Europe (380-385 MHz/390-395 MHz) is heavily congested. The application of cognitive technologies to address White Space could definitely help mitigate the problem.
SDR is not a new concept, especially not in the military domain, but recently it is arousing more interest as it is seen as a complementary technology to Cognitive Radio. Although CR must not be necessarily based on SDR, it is clear that SDR can be considered as one possible enabler of Cognitive Radio Technology and so the two technologies are definitely complementary from this perspective. Needless to say that both CR and SDR might have some regulatory aspects to consider and this is currently under investigation in different fora.
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