A motivating overview of cognitive radio: Foundations, regulatory issues and key concepts

The radio frequency spectrum is a scarce natural resource and its efficient use is of the utmost importance. A fundamental problem facing the future wireless systems is where to find suitable spectrum bands to meet the demand of future services. A promising technique to improve the spectrum utilization under a lot of investigation is the cognitive radio (CR) concept. This paper provides an overview of a CR study with discussion on enabling techniques for CR, measurements on current spectrum use, forthcoming standardization activities and some findings from our recent research studies on spectrum sensing, frequency management, and power control. The measurements on current spectrum use have identified that in general the overall spectrum occupancy is low. However, the overall spectrum occupancy does not characterize the actual situation adequately and better measures are needed. International Telecommunication Union Radiocommunication sector (ITU-R) has started standards activities on CRs, in particular on the measurement of spectrum occupancy and CR systems in the mobile service, indicating that the inclusion of the CR concept into the future regulatory framework is topical. Reliable spectrum sensing is a crucial task of the CR and proper performance assessment is important. If the future availability times of spectrum holes can be predicted, intelligent channel selection with the predicted channel information can be useful. A power control candidate for the CR system is the truncated inverse power control.