3.1 Introduction

Cognitive radio has evolved to include a wide range of technologies for making wireless systems more flexible via more flexible transceiver platforms and enhanced computational intelligence. Dynamic spectrum access networks [1, 2] evolved rapidly from regulatory rulings of the past few years [7]. In addition, research towards context-aware services has resulted in interdisciplinary integration of complementary but somewhat isolated technologies: perception, planning and machine learning technologies from artificial intelligence on the one hand, and on the other hand software radio technologies that had come to include self-description in the extensible markup language, Radio XML [3 5]. The first significant radio-domain application for such smarter radios was the autonomous sharing of pooled spectrum [6], which the US Federal Communications Commission (FCC) endorsed relatively soon thereafter to encourage the development of secondary spectrum markets [7]. The original visionary formulation of the ideal Cognitive Radio (iCR) remains in development. iCR was formulated as an autonomous agent that perceives the user s situation (shopping or in distress) to proactively assist the user with wireless information services, particularly if the user is too busy or otherwise occupied to go through the tedium of using the cell phone, such as when in personal distress [8]. At the 2004 Dagstuhl workshop [9], cognitive radio was extended to Cognitive Wireless Networks (CWN), which has become a research area with its own conference on cognitive radio oriented wireless networks, CrownCom...