Editorial: Special Issue on Cognitive Radio Networks and Communications

Cognitive radio networks and communications is an emergent paradigm to address the spectrum scarcity challenge in the wireless community. Currently, different wireless systems are regulated by a fixed spectrum assignment strategy. This policy partitions the whole spectrum into a large number of different ranges. Each piece is exclusively used by a specific wireless system. This leads to an undesirable situation that some systems may only use the allocated spectrum to a very limited extent while others have very serious spectrum insufficiency situation. Cognitive radio is believed to be a highly potential technology to address these issues. However, it is still in the very early stage of research and development. There are a number of technical, economical, and regulatory challenges to be addressed. This special issue aims to foster the dissemination of high quality research in cognitive radio networks and communications. Original papers are solicited in all aspects of cognitive radio including physical layer issues, architectures, protocol designs, theoretical studies, practical applications, and experimental prototypes. To guarantee the quality, in this special issue, we only include the following eight papers at this special issue. The first paper, entitled “Evaluation of Dynamic Channel and Power Assignment for CognitiveNetworks”, introduces a unifying optimization formulation to describe the dynamic channel and power assignment (DCPA) problem and an evaluation method for comparing DCPA algorithms. The second paper is entitled “Joint Bandwidth and Power Allocations for Cognitive Radio Networks with Imperfect Spectrum Sensing”. In this paper the authors study the joint