Cognitive Radios and their Role in Efficient Allocationof the Spectrum

Abstract

Today’s wireless networks are characterized by fixed spectrum assignment policy. The limited available
spectrum and the inefficiency in the spectrum usage necessitate a new communication paradigm to exploit
the existing wireless spectrum opportunistically. This new networking paradigm is referred to as Dynamic
Spectrum Access (DSA) and cognitive radio networks. Cognitive radio is a paradigm for wireless
communication in which either a network or a wireless node changes its transmission or reception
parameters to communicate efficiently avoiding interference with licensed or unlicensed users. In practice,
the spectrum allocated to licensed primary users is not utilized properly. The secondary unlicensed users
can sense and utilize the unutilized spectrum.