Certain investigations in cognitive radio with optimal transmissions and rate adaptation with varying channel characteristics

Abstract

Spectrum with reconfigurable measures has made wireless newlinecommunication susceptible. But the extent of re-configurability lies in the newlineenvironment which determines the susceptible data transfer. The signal losses newlinescenario in wireless communications can be attributed to three means. The newlinefirst is based on distance (large scale fading), the second on obstacle and newlinefading (medium scale fading) and the third based on multipath denoted as newlinesmall scale fading.In this focus the environment is defined by small scale fading. The newlinefirst is based upon a non fading channel where Gaussian noise model newline(Additive White Gaussian Noise) is used. Then the two fading models newlineRayleigh and Rician are being used.This design of cognitive radio is roughly divided in to two types one of which is user primary which is licensed and has the spectrum for the newlinetotal duration. The other type is the secondary user or cognitive user wherein newlinespectrum is accessible only in the absence of primary user or should confine newlineits transmission with limited capabilities.The first design on this research focuses on AWGN channel .The validation of the channel is made in the presence and absence of cognitive newlineuser. Two protocols have been proposed with multichannel capabilities, newlinenamely: Particle Swarm Optimization based Cognitive newline newline