Date Added: Sep 2012
Spectrum sensing is the basic and essential mechanisms of Cognitive Radio (CR) to find the unused spectrum. This paper presents an overview of CR architecture, discusses the characteristics and benefits of a CR. Energy detection-based spectrum sensing has been proposed and used widely because it doesn't require transmitted signal properties, channel information, or even the type of modulation. In this paper, a survey of energy detector over Additive White Gaussian Noise (AWGN), different fading channels for spectrum sensing methodologies in cognitive radio is presented. Theoretical analysis of time domain energy detection and threshold setting is investigated.