A survey of cognitive radio technologies and their optimization approaches

Although Cognitive radio (CR) is regarded as a promising technology to provide high bandwidth to mobile users via heterogeneous wireless network architectures and dynamic spectrum access techniques, cognitive radio networks (CRNs) may also impose some challenges due to factors such as the ever increasing complexity of network architecture and the increasing complexity with configuration and management of large-scale networks. In this paper, fundamentals of CR, including spectrum sensing, spectrum management, spectrum mobility and spectrum sharing, are surveyed, with their paradigms of self-organization being emphasized. Besides, variant aspects of self-organization paradigms in CRNs, including critical functionalities of Media Access Control (MAC)- and network-layer operations, are surveyed. This survey also identifies new directions and open problems in CRNs.