Cognitive radio has been found to be the technology to satisfy the huge demand for applications of high data rates that increase the number of users in wireless networks. Cognitive radio is a very interdisciplinary topic as it includes dynamic spectrum access and policies, flexible system architectures, learning, context awareness and cooperative networking. However, most of the current cognitive radio work targets spectrum sensing and spectrum allocation without considering the impact of optimization on the performance of the network. Mitola's vision intended to build context-sensitive smart radios that are able to adapt to the wireless environment conditions while maintaining quality of service support for different applications. In this book, we study cognitive radio from a system point of view focusing closely on architectures, techniques and algorithms that can enable intelligent operations for spectrum allocation and radio reconfiguration optimization. A modular cognitive resource management framework is investigated, which facilitate a development of flexible control and optimization techniques for resources management in wireless networks on diverse radio environments.