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Title: Frequency offset estimation for orthogonal frequency division multiplexing
Authors: NG KIM PIAU
Keywords: OFDM frequency estimation blind sub-carrier placement
Issue Date: 16-Oct-2004
Source: NG KIM PIAU (2004-10-16). Frequency offset estimation for orthogonal frequency division multiplexing. ScholarBank@NUS Repository.
Abstract: In this thesis, we are concerned with carrier frequency offset for a flexible OFDM framework where the placement of the activated sub-carriers is arbitrary and may vary from one OFDM symbol to another. We adopt a maximum likelihood estimate (MLE) approach, in which we search for the frequency offset that minimises the total energy of the null sub-carriers. By this method, the MLE may become ambiguous in the presence of channel nulls and we have derived the criterion to avoid this ambiguity through the judicious placement of the null sub-carriers. We have also derived the mean squared error of the MLE using small perturbation analysis and verified the theoretical results by computer simulation. We also proposed a random sub-carrier placement strategy coupled with deterministic hopping to cope with the ambiguity problem. Lastly, we show that, by transforming the problem of minima search to root search and applying Newton Raphsona??s method, the number of search iterations can be reduced
Appears in Collections:Master's Theses (Open)

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