Date Added: May 2010
Over the last decade the world of wireless communications has been undergoing some crucial changes, which have brought it at the forefront of international research and development interest, eventually resulting in the advent of a multitude of innovative technologies and associated products such as WiFi, WiMax, 802.20, 802.22, wireless mesh networks and software defined radio. Such a disparate and highly varying radio environment calls for intelligent management, allocation and usage of a scarce resource, namely the radio spectrum. One of the most prominent emerging technologies that promise to handle such situations is cognitive radio. Cognitive radio systems are based on software defined radio technology and utilize intelligent software packages that enrich their transceivers with the highly attractive properties of self-awareness, adaptability and capability to learn.