Decision Feedback Equalizer Seeding for Bursty Signal Gaps

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Solution Overview

Problem

Decision feedback equalizers (DFEs) face limitations in bursty signaling systems due to the requirement of uninterrupted symbol transmission for channel-response estimation, making them less applicable in systems with irregularly spaced symbols or bursty channels.

Innovation Solution

The implementation of a burst-mode DFE receiver that dynamically seeds decision feedback equalizers, allowing for gap-tolerant operation by detecting and measuring gaps between burst transmissions to improve signaling performance, reduce bit error rates, and enable higher signaling frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a decision feedback equalizer is used to improve signaling performance and reduce bit error rates, then signaling margin and reliability are improved, but the system requires uninterrupted symbol transmission which limits applicability in bursty signaling systems

Engineering Contradiction:
Improvebit error rateVSAvoidapplicability in bursty signaling systems
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic seeding of the DFE feedback filter by detecting gap durations and selectively loading seed values into the feedback filter during gaps between symbol bursts. This allows the DFE to adapt its operation between continuous and bursty transmission modes, maintaining reliability across different signaling conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes operational parameters by detecting gap durations and adjusting DFE feedback filter seeding accordingly. When gaps are detected, the system loads predetermined seed values into the feedback filter; when continuous transmission occurs, normal operation resumes. This parameter adaptation enables the DFE to function effectively in both continuous and bursty signaling systems.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If a decision feedback equalizer operates in bursty channels with irregularly spaced symbols, then versatility in signaling systems is improved, but channel-response estimation becomes inaccurate without uninterrupted symbol transmission

Engineering Contradiction:
Improveadaptability to bursty channelsVSAvoidchannel-response estimation accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by loading predetermined seed values into the DFE feedback filter during gap periods between symbol bursts. These seed values are prepared in advance and loaded before the next symbol burst arrives, ensuring the feedback filter is properly initialized to maintain accurate channel-response estimation when transmission resumes.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism - a gap detection and seed loading system that operates during transmission gaps. This intermediary detects the absence of symbols, loads appropriate seed values into the feedback filter, and prepares the DFE for accurate operation when the next symbol burst arrives, thereby maintaining estimation accuracy despite interrupted transmission.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If gap detection and dynamic seeding mechanisms are added to enable burst-mode operation, then adaptability to bursty signaling systems is improved, but device complexity increases

Engineering Contradiction:
Improveburst-mode operation capabilityVSAvoidcomplexity of gap detection and seed loading circuitry
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements self-service by having the system automatically detect gaps in symbol transmission and autonomously load appropriate seed values into the feedback filter without external intervention. The DFE monitors its own input stream, identifies gap conditions, and performs self-correction by loading predetermined seed values, thereby enabling burst-mode operation with minimal additional control complexity.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3329593B1Burst-tolerant decision feedback equalization
Publication Date: 2021.03.03 RAMBUS INC
  • EP3329593B1 patent drawingFigure 1~2
  • EP3329593B1 patent drawingFigure 3
  • EP3329593B1 patent drawingFigure 4~6

AI summary

A first sequence of data bits is shifted into storage elements of a signal receiver during a first sequence of bit-time intervals, and a memory access command indicates that a second sequence of data bits is to be received within the signal receiver during a second sequence of bit-time intervals. Contents of the shift-register storage elements are conditionally overwritten with a predetermined set of seed bits, depending on whether one or more bit-time intervals will transpire between the first and second sequences of bit-time intervals. Equalization signals generated based, at least in part, on contents of the shift-register storage elements are used to adjust respective signal levels representative of one or more bits of the second sequence of data bits.