Spectrum Sensing & Channel State Estimation for Cognitive Radio Using Pointing Vector Theorem
In this paper, the authors present an overview of cognitive radio and cognitive radio network. The report list enabling technique for cognitive radio and describe the state-of-art in cognitive radio standards, regulation, product and research. The availability of spectrum holes, i.e., frequency band assigned to a primary user but that are vacant in a given place at a given time, can be estimated with spectrum sensing technique, such as energy detection & feature detection. When little or no knowledge of the primary user signal is available, energy detection is useful while feature detection can exploit a priori information about the used waveforms.