| 摘要 |
The present invention relates to a method and a system for estimation of the frequency offset in the digital transmission which is applicable for arbitrary linear modulations, dispersive channels, and general additive impairments. In a first step of the method N derivatives of the received signal are formed through discrete frequency shifts. Subsequently, these derivatives are preprocessed and equalized in an appropriate manner. On the basis of reliability information about the corresponding reconstructed symbol sequences, which is given in the form of metrics Mv which are obtained from internal variables of the equalizer (in case of hard-output equalization) or its output values (in case of soft-output equalization), an estimate of the frequency offset can be established by analysing them in connection with the N corresponding frequency shifts fv. Herein it is to be noted that the N equalizations do not necessarily have to equalize the entire received signal, but only part thereof. In this way, a frequency offset estimation can be carried out with a moderate complexity involved. After the estimation, the frequency offset is compensated and a conventional preprocessing and equalization is performed.
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