Extending the Reach of Cognitive Radio

There has been significant research progress reported over the last few years in the development of cognitive radio technologies. This paper reviews some of these results, describes several critical issues to integrate these results in usable products, and describes the large-scale Defense Advanced Research Projects Agency efforts to further develop and exploit dynamic spectrum access, and initiate development and operational use of cognitive networking and a new generation of affordable wireless technology. This paper also describes future research needs to fully exploit cognitive radio technology and addresses the challenges that will arise with its large-scale deployment.