Sequential blind convergence process in an adaptive decision feedback equalizer

Abstract

A blind convergence process for an adaptive decision feedback equalizer having an quadrature amplitude modulation (QAM) slicer, a forward filter defined by a plurality of forward tap coefficients and a feedback filter defined by a plurality of feedback tap coefficients. The blind convergence process includes the step of initializing the forward tap coefficients of the forward filter and the feedback tap coefficients of the feedback filters with predetermined values. The QAM slicer operates in two modes: a clustering mode and a decision directed mode. The clustering mode includes the step of updating only the forward tap coefficients of the forward filter for a prescribed start-up QAM index (such a 4 QAM). The decision directed mode is predefined for set of QAM indexes having values n1, n2, . . . nm, and includes: updating the forward tap coefficients of the forward filter for a QAM index ni selected from the predefined set of QAM indexes, and updating the feedback tap coefficients of the feedback filter for the QAM index ni selected from the predefined set of QAM indexes. The decision directed processing steps are repeating the next QAM index ni+1 of the predefined set of QAM indexes until the equalizer has converged to its highest available QAM index or until the equalizer has converged to the highest operable QAM index (constellation). The QAM index set can be {4,16,64,256}.

Dependencies are inferred from the claim text.