Cognitive radio systems: Overview and challenges

Abstract

Cognitive radio system (CRS) is a disruptive technology targeting very high spectral efficiency. This paper presents an overview of CRS and summarizes the related regulation and standardization status. We point out some key research challenges, especially implementation challenges of cognitive radio and deduce research directions in CRS. Despite numerous challenges, the timeframe for the success of CRS is more linked to the economical and business model than real technological issues.