The central goal of this book is to teach the reader how to design user interfaces that will enable people to learn computer systems quickly and use them eff ectively, effi ciently, and comfortably. The interface issues addressed are prima

Cognitive Radios (CRs), which sense the spectrum and implement opportunistic sharing when no licensed user is found to use it, are able to improve the efficiency of spectrum. Spectrum sensing must be firstly solved in CRs. Cooperative sen