Review on Classical to Deep Spectrum Sensing in Cognitive Radio Networks

Cognitive Radio (CR), a promising next-generation wireless network has been progressing well that deals with the scant radio spectrum issues using a dynamic spectrum access policy. Spectrum Sensing (SS) the main enabling key function of CR, finds the unused spectrum segment of the licensed users and utilizes opportunistically the available user. Classical spectrum sensing hardly performs well in realistic time-variant fading channels where cooperation among users improves the spectrum efficiency using the sparsely diverse user concept. The efficient deep sensing techniques using advanced communication technology are likely to be useful for next-generation 5G networks having massive connectivity and cooperation overhead issues. This paper gives a brief overview of different sensing techniques used from instant to 5G networks.