Patent ID: 7496138
Filing Date: 2009-02-24
Classification: H04B,H04L

Abstract:
1. A step-size estimator for controlling the step-size of an adaptive equalizer having an equalizer tap update unit, the step-size estimator comprising: a speed estimator for estimating the apparent speed of a channel; and a step-size mapping unit for mapping the estimated apparent speed to at least one parameter used by the adaptive equalizer to update at least one filter tap coefficient used by the adaptive equalizer, wherein the speed estimator comprises: a tap coefficient extractor for extracting at least one equalizer filter tap coefficient from filter tap coefficients generated by the equalizer tap update unit; an angle calculator for generating a phase of the extracted equalizer filter tap coefficient; a tapped delay line (TDL) for generating N delayed samples based on a vector of N delay values and the phase of the extracted equalizer filter tap coefficient; a phase difference function generator for generating N phase difference function values based on the N delayed samples and the phase of the extracted equalizer filter tap coefficient; an averaging filter for averaging the magnitude of the phase difference function values to generate an average phase difference vector having a plurality of elements; a normalizing unit for normalizing the elements of the averaged phase difference vector to generate a normalized phase difference function vector having a plurality of elements; a delay calculator for comparing each element of the normalized phase difference function vector to a threshold to generate a delay at the threshold; and a speed mapping unit for mapping the delay at the threshold to the speed estimate.