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Multichannel Estimation and Equalization Algorithm for Asynchronous Uplink DS/CDMA

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Abstract

This paper addresses the problem of channel estimation andequalization in asynchronous uplink DS/CDMA. We propose a completereceiver structure which contains a multichannel estimator suitablefor time-varying channels, a MMSE equalizer and a propagation delayestimator. The multichannel estimator is a stochastic gradientalgorithm which does not require any knowledge about the propagationdelays. It estimates a matrix which contains a linear combination ofthe impulse response of each channel and the propagation delays. Thisestimate is used to derive a MMSE equalizer. In the despreading stageknowledge on the integer part (chip period multiple) of thepropagation delays is needed. Two reduced complexity schemes forpropagation delay estimation are presented. The channel estimatorconvergence is studied in stationary conditions while the overallalgorithm performance is demonstrated by using simulations intime-varying channel conditions.

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Authors and Affiliations

  1. Signal Processing Laboratory, Helsinki University of Technology, P.O. Box 3000, FIN-02015, HUT, Finland

    Marius Sirbu & Visa Koivunen

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  1. Marius Sirbu
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  2. Visa Koivunen
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Sirbu, M., Koivunen, V. Multichannel Estimation and Equalization Algorithm for Asynchronous Uplink DS/CDMA. Wireless Personal Communications 26, 33–52 (2003). https://doi.org/10.1023/A:1025378901359

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