A new blind adaptive interference suppression scheme for acquisition and MMSE demodulation of DS/CDMA signals

We present an efficient blind algorithm for estimating the code timing of a desired user in an asynchronous direct-sequence code-division multiple-access (DS/CDMA) system over frequency-nonselective-fading channels. The proposed algorithm acquires the code timing explicitly and results in a near-far resistant minimum mean-squared error (MMSE) demodulation without requiring the knowledge of the timing information, amplitudes, and transmitted symbols of all transmissions. The only required knowledge is the information of the signature sequence used by the desired transmission. Several computer simulations are done for additive white Gaussian channels, Rayleigh fading channels, and two-ray Rayleigh fading multipath channels, respectively. Numerical results show that the new algorithm is near-far resistant to the multiple-access interference (MAI) in the DS/CDMA system