Physical and mac layer adaptive spectrum sensing schemes for cognitive radio networks

Abstract

The utilization of spectrum resources and the regulation of radio emissions are coordinated by Federal Communications newlineCommission FCC FCC assigns the spectrum to licensed or primary newlineusers on a long term basis Due to the long term assignment of the newlinespectrum a large portion of the spectrum is underutilized On the other newlinehand Spectrum scarcity is an emerging problem because of the need of newlinehigher data rates in multimedia wireless communication networks With newlinethe limitations of the natural frequency spectrum it becomes obvious newlinethat the current static or fixed frequency allocation schemes cannot newlineaccommodate the requirements of an increasing number of higher data newlinerate devices Since in fixed frequency allocation only the assigned or newlinelicensed users have the right to access the spectrum and other users are newlinenot allowed to use it irrespective of the idle or busy status of the newlinelicensed spectrum Therefore in fixed frequency allocation the spectrum newlineutilization efficiency is very less The fixed spectrum underutilization newlineand spectrum scarcity problems necessitate a new communication newlineparadigm to exploit the existing wireless spectrum opportunistically newlineDynamic Spectrum Access DSA is proposed to solve these current newlinespectrum inefficiency problems newline newline