Automated erasure slicer threshold control and modification of symbol estimates to be erased

摘要

Methods and systems to vary an erasure slicer threshold based on a measure computed from prior soft and/or hard symbol decisions, identify reliable symbol estimates based on the threshold, identify unreliable symbol estimates for erasure based on the threshold, modify the identified symbol estimates, output the reliable symbol estimates and the modified symbol estimates as erasure slicer decisions, and filter the decisions in a feedback filter of a decision feedback equalizer (DFE). The erasure slicer threshold may be based on signal-to-noise ratio (SNR) or mean-squared-error (MSE). A symbol estimate may be identified for erasure when a coordinate of the corresponding soft decision is within an erasure area defined by the threshold. Symbol modification may include replacing a corresponding coordinate of the symbol estimate with a coordinate of a decision boundary associated with the erasure area.

主权项

1. An apparatus, comprising:
a soft decision system to determine soft decisions for symbols of a signal as coordinates within a quadrature amplitude modulated (QAM) constellation; a hard decision system to determine hard decisions for the symbols as points within the QAM constellation based on the soft decisions; an erasure slicer to evaluate the soft decisions based on a threshold distance, including to determine if a coordinate of a soft decision falls within the threshold distance of a boundary between points of the QAM constellation; and a threshold module to vary the threshold distance based on variations in a difference between the soft decisions and the hard decisions; wherein the soft decision system is configured to determine the soft decisions based on samples of the QAM signal and an output of the erasure slicer.