DFE Receiver Burst Correction with a Second FFE
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Solution Overview
Problem
Existing decision feedback equalization (DFE) systems suffer from error propagation and burst errors due to incorrect decisions, which are not effectively addressed by current methods.
Innovation Solution
A receiver system incorporating a decision feedback equalizer (DFE) and a second feed forward equalizer (FFE) with correction logic to detect the end of burst error (EoB) and determine the earliest start of burst (SoB), using sequence comparisons and maximum likelihood sequence detection to correct burst errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If decision feedback equalization (DFE) is used to correct intersymbol interference without amplifying noise, then effectiveness for long-reach channels is improved, but error propagation and burst errors occur due to incorrect decisions
Solution Approach 1:
The patent introduces an error detection and correction module as an intermediary between the DFE and output. This module detects burst errors using a burst error detector that monitors decision symbols and identifies error patterns, then corrects them using a correction mechanism that replaces erroneous symbols with corrected values, thereby preventing error propagation while maintaining DFE's noise correction effectiveness
Solution Approach 2:
The patent implements feedback by feeding back corrected decision symbols from the error correction module to the DFE output. The burst error detector continuously monitors the DFE output and feeds error information back to trigger correction, creating a closed-loop system that actively suppresses error propagation while preserving the beneficial noise correction properties of DFE
2Reliability
If feedforward equalization (FFE) is used to equalize pre-cursor ISI, then equalization performance is improved, but signal-to-noise ratio (SNR) deteriorates due to noise amplification
Solution Approach 1:
The patent segments the equalization function into two distinct parts: a FFE component that handles only pre-cursor ISI equalization, and a DFE component that handles post-cursor ISI correction. By dividing the equalization task, the FFE operates with fewer taps and less aggressive filtering, thereby reducing noise amplification while still providing necessary pre-cursor equalization support
Data Source
AI summary
A receiver for providing a corrected output symbol sequence is disclosed. A decision feedback equalizer (DFE) generates an output sequence of DFE decision symbols; a second feed forward equalizer (FFE) generates a second equalized output symbol sequence; and correction logic, responsive to determination of an end of burst error position of a burst error sequence in the DFE output sequence, determines a candidate earliest start of burst position, and determines the corrected output symbol sequence by comparing the second equalized output symbol sequence with candidate symbol sequences that correspond to corrections of DFE decision output symbols in the burst error sequence.