A robust timing and frequency synchronization for OFDM systems

TitleA robust timing and frequency synchronization for OFDM systems
Publication TypeJournal Article
Year of Publication2003
AuthorsMinn, H., V. K. Bhargava, and K. B. Letaief
JournalWireless Communications, IEEE Transactions on
Volume2
Pagination822 - 839
Date Publishedjul.
ISSN1536-1276
Keywordsbit-error-rate performance, carrier-frequency synchronization, channel estimation, channel estimation scheme, error statistics, fine-timing estimates, frequency-offset estimates, maximum likelihood estimation, maximum likelihood principle, multipath channels, multipath Rayleigh fading channel, OFDM modulation, OFDM systems, peak-to-average power ratio, Rayleigh channels, steep rolloff timing metric, symbol-timing synchronization, sync detection capability, synchronisation, training symbol pattern
Abstract

A robust symbol-timing and carrier-frequency synchronization scheme applicable to orthogonal frequency-division-multiplexing systems is presented. The proposed method is based on a training symbol specifically designed to have a steep rolloff timing metric. The proposed timing metric also provides a robust sync detection capability. Both time domain training and frequency domain (FD) training are investigated. For FD training, maintaining a low peak-to-average power ratio of the training symbol was taken into consideration. The channel estimation scheme based on the designed training symbol was also incorporated in the system in order to give both fine-timing and frequency-offset estimates. For fine frequency estimation, two approaches are presented. The first one is based on the suppression of the interference introduced in the frequency estimation process by the training symbol pattern in the context of multipath dispersive channels. The second one is based on the maximum likelihood principle and does not suffer from any interference. A new performance measure is introduced for timing estimation, which is based on the plot of signal to timing-error-induced average interference power ratio against the timing estimate shift. A simple approach for finding the optimal setting of the timing estimator is presented. Finally, the sync detection, timing estimation, frequency estimation, and bit-error-rate performance of the proposed method are presented in a multipath Rayleigh fading channel.

URLhttp://dx.doi.org/10.1109/TWC.2003.814346
DOI10.1109/TWC.2003.814346

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