Blind equalization for CDMA systems with aperiodic spreading sequences

Multipath induced interchip-interference (ICI) alters waveforms of transmitted signals and presents a major obstacle to direct-sequence (DS) code-division-multiple-access (CDMA) communications. Since practical systems often employ aperiodic pseudorandom (PN) spreading sequences, source separation/equalization based on users signature waveforms may be prohibitive. We consider antenna array CDMA systems with aperiodic PN sequences and present a blind method to estimate the filter coefficients in a standard 2D RAKE receiver. A simple cost function is formulated based on which we derive a least-squares equalizer to effectively suppress both ICI and multiuser interference (MUI) by exploiting the channel diversities