Pilot-aided rayleigh fading channel estimation using MMSE estimator for DS-CDMA system

In this paper, we have developed a pilot-aided channel estimator for the direct-sequence code-division multiple-access (DS-CDMA) communication system based on the minimum mean-square error (MMSE) estimate of the attenuated antipodal transmitted signals in the presence of both fading and noise. Specifically we have considered the scenario of downlink synchronous DS-CDMA transmitter along with Rayleigh fading and the additive white Gaussian noise (AWGN) environment. The proposed receiver consists of a matched filter which is matched to the signature waveform of the desired user followed by a nonlinear estimation device. This non-linear device results from the MMSE estimate of the attenuated transmitted signal. Simulations were carried out to corroborate the theoretical findings for different values of signal-to-noise ratio (SNR) and number of users.