Definition - What does Cognitive Radio mean?
Cognitive radio's main purpose is to detect and share unused spectrum with other systems without creating harmful interference. This includes spectrum management, or finding the best available spectrum to meet user communication requirements.
Techopedia explains Cognitive Radio
Cognitive radio was first proposed in a 1998 seminar by Joseph Mitola III at the Royal Institute of Technology in Stockholm, Sweden. A year later, this new wireless communication approach was published in an article by Mitola and Gerald Maguire Jr. At first, it was foreseen as a software-defined radio extension - full cognitive radio - in which all observable wireless node parameters are considered. This was Mitola’s original idea, but most modern research of this technology focuses on spectrum-sensing cognitive radio, which is simpler. The main hindrance to cognitive radio, however, is actually designing a high-quality sensing device and accompanying algorithms for exchanging spectrum-sensing data between different nodes, as simple energy detectors cannot guarantee accurate signal detection.