Performance enhancement and Analysis of wavelet based DS CDMA Over AWGN and fading channels

Abstract

This dissertation investigates by simulation modeling, the use of newlineWavelets in Direct Sequence Code Division Multiple Access DS CDMA newlinecommunication systems for denoising During World War II the idea of DSCDMA newlinewas originally developed by the Allies for military purposes Besides newlinemilitary applications there is a tremendous growing and intense interest in newlineCDMA communication systems for evolving other applications like personal newlineCommunications satellite mobile communications and cellular mobile newlineCommunications In CDMA each user is assigned a distinct code and more newlinenumber of users can transmit data simultaneously using the same frequency newlineAll the users are distinguished by their codes This technique is said to be newlinespread spectrum as the transmission bandwidth is much greater than the newlineminimum bandwidth required to transmit information newlineAs the demand for reducing the Bit Error Rate BER rises the newlineneed to develop more efficient spread spectrum system increases The BER of newlineany transmission system is a decreasing function of the Signal to Noise Ratio newline SNR So in order to reduce the BER it is necessary to increase the SNR newlineHowever practical systems are power limited and the signal power can be newlineincreased only up to a certain value newline newline