Efficient spectrum utilization: A cognitive approach

Cognitive Radios (CRs) are enablers of opportunistic wireless spectrum usage. Their key roles (such as spectrum sensing, spectrum sharing etc.) provide more efficient spectrum utilization embedding higher degree of intelligence in wireless systems. This paper gives an overview of the most important CR characteristics and the standardization efforts in the area. Additionally, the paper reports on measurements of spectrum (under)utilization done on various places in the world.