  In the beginning of 21st century there has been a dramatic shift in the
market dynamics of telecommunication services. The transmission from base
station to mobile or downlink transmission using M-ary Quadrature Amplitude
modulation (QAM) and Quadrature phase shift keying (QPSK) modulation schemes
are considered in Wideband-Code Division Multiple Access (W-CDMA) system. We
have done the performance analysis of these modulation techniques when the
system is subjected to Additive White Gaussian Noise (AWGN) and multipath
Rayleigh fading are considered in the channel. The research has been performed
by using MATLAB 7.6 for simulation and evaluation of Bit Error Rate (BER) and
Signal-To-Noise Ratio (SNR) for W-CDMA system models. It is shows that the
analysis of Quadrature phases shift key and 16-ary Quadrature Amplitude
modulations which are being used in wideband code division multiple access
system, Therefore, the system could go for more suitable modulation technique
to suit the channel quality, thus we can deliver the optimum and efficient data
rate to mobile terminal.
