This paper deals with synchronous Direct-Sequence CDMA transmission using orthogonal channel codes in time-varying, frequency selective multi-path channels, motivated by the forward link in 3G CDMA systems. In recent years, receivers based on channel equalization on the chip-level prior to despreading have been proposed for 3G wideband CDMA downlink. In this paper, we evaluate the efficacy of adaptive chip-level MMSE estimation of the (multi-user) synchronous sum signal transmitted by the

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... tation, followed by a correlate and sum. We use the conjugate gradient (CG) algorithm for MMSE estimation and the pilot channel for training. Our simulations show that, training-based CG-MMSE equalizer can achieve much better error rates compared to RAKE reception, over a wide range of SNRs and system loads.