CHAPTER Cognitive radio evolution Joseph Mitola III Stevens Institute of Technology, United States 20 20.1 INTRODUCTION Introduced in 1998­1999, cognitive radio has become an all-encompassing term for a wide variety of technologies from dynamic spectrum access to reconfigurable networks. As originally published [6,678], the concept emphasized enhanced qual- ity of information (QoI) for the user, with spectrum agility framed as a means to an end and not as an end in itself. The first research prototype cognitive radio (CR1),