Special issue on "Cognitive Radio Technologies"

Cognitive radio is considered as a radio that is computationally intelligent and aware of the resources and has the capability to decide and select the wireless communication parameters which are considered to be the best choice for operation in a particular scenario. The novel functionalities of the cognitive radio networks such as spectrum sensing, spectrum management, spectrum mobility and spectrum sharing have received considerable global attention and the impact of these functions on upper layer protocols are being investigated. A paper, 'Spectrum Challenges and Solutions by Cognitive Radio- An Overview', by K. Sridhara, A. Chandra and P.S.M. Tripathi, offers an overview of the problems faced by wireless communications related to the spectral use. 'Cognitive Radio Dynamic Access Techniques', a paper by I. Budiarjo, M. K. Lakshmanan and H. Nikookar, is a tutorial paper for understanding the physical layer design and transmission techniques for cognitive radios.