Oscillator Holdover Modeling for Reference Loss Timing Accuracy

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Solution Overview

Problem

Network nodes with local oscillators disciplined by external timing references face performance impairment when the external reference is unavailable, requiring costly and time-consuming human intervention to maintain timing accuracy, especially in stringent standards like WiMAX and LTE systems.

Innovation Solution

A method that trains mathematical models of the local oscillator using external reference signals to predict correction signals, determines frequency and time errors, and selects the model with the smallest time error to maintain oscillator discipline when the external reference is unavailable, allowing for automated holdover operation within specified error thresholds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an external timing reference source is used to discipline the local oscillator, then timing accuracy is improved, but the system becomes vulnerable to performance impairment when the external reference is unavailable

Engineering Contradiction:
Improvetiming accuracyVSAvoidoperational reliability during reference unavailability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent trains multiple mathematical models of the local oscillator characteristics during periods when the external reference is available. This preliminary action stores learned oscillator behavior patterns that can be applied when the reference becomes unavailable, enabling the system to maintain timing accuracy without immediate human intervention.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses its own historical correction signal data to train mathematical models that can autonomously predict future correction needs. When the external reference is unavailable, the trained models self-generate correction signals based on learned oscillator patterns, allowing the system to service itself without external assistance.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If human intervention is used to correct timing when external reference is unavailable, then timing accuracy is maintained, but operational cost and time consumption increase

Engineering Contradiction:
Improvetiming accuracyVSAvoidtime for human intervention
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system autonomously maintains timing accuracy by using trained mathematical models to generate correction signals when the external reference is unavailable. This self-service capability eliminates the need for human operators to manually correct timing, thereby reducing both time loss and operational costs while maintaining the required timing precision.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If a higher accuracy local oscillator is used, then timing performance is improved, but device cost increases

Engineering Contradiction:
Improvetiming performanceVSAvoiddevice cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

Instead of using a more expensive high-accuracy oscillator, the patent changes the operational parameters by training multiple mathematical models that characterize the oscillator's behavior under different conditions. These models enable a lower-cost oscillator to achieve higher effective accuracy through software-based correction, thereby improving timing performance without increasing hardware cost.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates mathematical copies or models of the local oscillator's behavior rather than physically upgrading the oscillator itself. These virtual models capture the oscillator's characteristics and can be used to predict and correct its drift, achieving the effect of a higher-accuracy oscillator without the associated cost.

Inventive Principle:
Principle #26Copying

4Measurement precision

If multiple mathematical models are trained, then prediction accuracy is improved, but computational complexity increases

Engineering Contradiction:
Improveprediction accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the oscillator characterization into multiple separate mathematical models, each trained on specific aspects of oscillator behavior. This segmentation allows the system to select and apply only the most appropriate model for given conditions, improving prediction accuracy while managing computational complexity through selective model usage rather than continuously running all models.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS8847690B2System and method for built in self test for timing module holdover
Publication Date: 2014.09.30 MALIKIE INNOVATIONS LTD
  • US8847690B2 patent drawing
  • US8847690B2 patent drawing
  • US8847690B2 patent drawing

AI summary

Aspects of the embodiments include a method for synchronizing a device having an oscillator to a reference signal. A correction signal can be determined based on the reference signal. A mathematical model of the oscillator can be trained based at least upon the correction signal. A predicted correction signal for the trained mathematical model can be determined. A time error using the predicted correction signal can be generated to assess suitability of the trained mathematical model for disciplining drift in the oscillator and synchronizing the device when the reference signal is not available.