Date Added: Jul 2012
Due to the ever-increasing scarcity of spectrum resources, Cognitive radio networks have become an important part of wireless networking system. Such type of networks perform co-operative spectrum which sense to find white spaces and apply various policies to determine when and in which bands they may communicate. A number of wireless applications have been developing over the last decade. Most of the frequency spectrum has already been certified by Government agencies, like Federal Communications Commission (FCC). Therefore, there is an apparent spectrum scarcity for new wireless services. So the unused spectrum is efficiently utilized by the Cognitive radio for secondary usage without interfering a primary licensed user.