Code-timing estimation for CDMA systems with bandlimited chip waveforms

Rensheng Wang, Hongbin Li

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations

Abstract

In this paper, we present a novel code-timing estimator for asynchronous direct-sequence (DS) code-division multiple-access (CDMA) systems utilizing bandlimited chip waveforms. We start from a maximum likelihood (ML) approach that models the inter-symbol interference (ISI) and multiple-access interference (MAI) as a colored Gaussian process with unknown covariance matrix in the frequency domain. The exact ML estimator is highly nonlinear and requires iterative searches over multidimensional parameter space that is impractical to implement. To deal with this difficulty, we invoke asymptotic (large-sample) approximations of the ML criterion and reparameterization techniques, which lead to an asymptotic ML estimator that yields codetiming and channel estimates via efficient non-iterative quadratic optimizations. To benchmark the proposed estimator, we provide Cramér-Rao bound (CRB) analysis for the code-timing estimation problem. Numerical simulation results are presented to illustrate the performance of the proposed code-timing estimator for bandlimited CDMA in multipath fading channels.

Original languageEnglish
Pages (from-to)2440-2444
Number of pages5
JournalConference Record - International Conference on Communications
Volume4
StatePublished - 2003
Event2003 International Conference on Communications (ICC 2003) - Anchorage, AK, United States
Duration: 11 May 200315 May 2003

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