Evolution and Future Trends of Research in Cognitive Radio: A Contemporary Survey
For wireless communications, the right to access the spectrum or license is generally defined by frequency, space, transmission power, spectrum owner (i.e., licensee), type of use, and the duration of license. The Cognitive Radio (CR) paradigm for designing next-generation wireless communications systems is becoming increasingly popular, and different aspects of it are being implemented in currently available wireless systems. In the last decade, a significant amount of research efforts has been made to solve CR challenges, and several standards related to CR and dynamic spectrum access have been developed. Also, there have been advances in software-defined radio platforms to implement the CR systems.