Isochronous Packet Dropout Minimization via Self-Synchronization

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Solution Overview

Problem

Isochronous data packets experience phase slips when crossing plesiochronous boundaries, leading to message dropouts or errors due to timing discrepancies between transmitter and receiver, especially exacerbated by jitter, which existing methods like jitter buffers attempt to address but introduce additional delay.

Innovation Solution

A self-synchronizing technique that dynamically adjusts data processing by monitoring the phase crossover and utilizing two control signals to align received packet data flow with processing, allowing for single packet error occurrence during phase transition without the need to detect phase slip direction or magnitude, thereby minimizing message dropout rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If jitter buffers are used to cross the gap and absorb additional data packets, then message dropout errors are reduced, but additional delay is introduced in data transport

Engineering Contradiction:
Improvemessage dropout error reductionVSAvoiddata transport delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary detection of phase slip conditions and pre-adjusts the processing timing accordingly. By monitoring the phase relationship between transmitted and received packets and detecting when a phase slip is about to occur, the system proactively adjusts the processing time instant before the error occurs, preventing message dropout without requiring buffering delays

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses its own received packet timing information to detect phase slips and automatically adjusts its processing schedule. The receiver monitors the phase relationship, detects when phase slip occurs, and self-corrects by adjusting processing timing, eliminating the need for external jitter buffers or additional delay mechanisms

Inventive Principle:
Principle #25Self-service

2Reliability

If phase slip detection and correction mechanisms are implemented, then message dropout rates are reduced, but device complexity increases

Engineering Contradiction:
Improvemessage dropout rate reductionVSAvoidsynchronization mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system implements a feedback mechanism where the receiver monitors the phase relationship between transmitted and received packets, detects phase slips, and uses this information to adjust processing timing. The feedback loop continuously monitors packet arrival timing and automatically corrects phase misalignment by adjusting the processing time instant, maintaining synchronization without complex external control systems

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system changes the processing time instant parameter dynamically based on detected phase conditions. When a phase slip is detected, the system adjusts the processing timing parameter to occur at a different time instant that avoids the phase error, using simple parameter adjustment rather than complex mechanical or electronic correction mechanisms

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3349399B1Message dropout minimization when transporting isochronous packets across a plesiochronous boundary
Publication Date: 2021.10.13 HAMILTON SUNDSTRAND CORP
  • EP3349399B1 patent drawingFigure 1
  • EP3349399B1 patent drawingFigure 2

AI summary

A system for reducing message dropout rate in a communication system is provided. Message dropouts occur during transportation of isochronous datasets across a plesiochronous boundary. The system includes a first processing element (102) configured to operate in response to a first clock signal at a first clock speed. The system further includes a second processing element (104) configured to operate in response to a second clock signal at a second clock speed, different from the first clock speed. The second processing element (104) is operably connected to the first processing element (102) by a data bus. The first processing element (102) and the second processing element (104) are configured to indicate a fault when no dataset is received during a processing interval.