Cognitive radio networks: a practical perspective [Guest Editorial]

Contemporary wireless systems must meet increased bandwidth requirements due to the persistent trend for higher multimedia data rates. Increased bandwidth may be achieved by developing efficient strategies for spectrum management. The cognitive radio (CR) concept proposes to push the dynamic spectrum access and efficient resource allocation beyond its traditional limits, by introducing spectrum sharing, coexistence, and cooperation among heterogeneous wireless networks. Although this approach has been recognized worldwide by standardization bodies, challenges and open issues still exist for its implementation in the real world.