Estimation algorithms of multiple channels and carrier frequency offsets in application to multiuser OFDM systems

Authors:
Lars Häring;Stefan Bieder;Andreas Czylwik;Thomas Kaiser
Affiliations:
Department of Communication Systems, University Duisburg-Essen, Duisburg, Germany;Sennheiser Electronic GmbH & Co KG, Germany;Department of Communication Systems, University Duisburg-Essen, Duisburg, Germany;Department of Communication Systems, Gottfried Wilhelm Leibniz University of Hannover, Germany
Venue:
IEEE Transactions on Wireless Communications
Year:
2010

Citing 2
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Channel-independent synchronization of orthogonal frequency division multiple access systems

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Abstract

This paper introduces new joint estimation methods of multiple carrier frequency offsets (CFOs) and channel impulse responses (CIR) in application to multiuser orthogonal frequency division multiplexing (OFDM) systems. The estimators are derived from the optimal maximum-likelihood (ML) principle. Complexity reductions are achieved by exploiting the correlation properties of the training sequence (TS). The grid search algorithm is converted into a polynomial root finding procedure which leads to low-complexity closed-form estimators for moderate CFOs. Furthermore, iterative estimators for larger CFOs are proposed. Numerical results confirm that the performance degradation due to the approximations compared to the Cramer-Rao bound (CRB) is small and may be negligible in practice.