Adaptive PTP Filtering for Packet Delay Variation Suppression
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Solution Overview
Problem
Packet delay variation in Precision Time Protocol (PTP) networks caused by inconsistent network traffic leads to instability in slave device clocks, as they are not accurately synchronized with primary reference clocks.
Innovation Solution
An integrated circuit with a microcontroller that receives phase offsets over time, determines a weight vector based on these offsets, and adjusts filter coefficients to implement adaptive filtering, reducing packet delay variation by synchronizing the slave device clock with both physical and IEEE 1588 clock layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If adaptive filtering with dynamic filter coefficients is implemented, then clock synchronization accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements adaptive filtering where filter coefficients are dynamically adjusted based on packet delay variation metrics. The system transitions from static to dynamic filtering by continuously updating coefficients according to current network conditions, thereby improving synchronization accuracy while managing complexity through adaptive rather than purely static designs
Solution Approach 2:
The system changes filter parameters (coefficients) based on measured packet delay variation. By monitoring network conditions and adjusting filter coefficients accordingly, the system optimizes synchronization accuracy for varying network states without requiring completely different filter designs for each condition
2Reliability
If filter coefficients are continuously adjusted based on packet delay variation, then noise inconsistency is reduced, but computational load increases
Solution Approach 1:
The patent applies filtering selectively based on measured packet delay variation thresholds. Rather than continuously adjusting filters at maximum intensity, the system applies partial filtering action only when packet delay variation exceeds acceptable levels, reducing unnecessary computational load while maintaining reliability when needed
Solution Approach 2:
The system implements feedback by monitoring packet delay variation and using this information to adjust filter coefficients. This closed-loop approach ensures filtering is applied appropriately based on actual network conditions, avoiding excessive computational effort during stable periods while maintaining noise consistency during variable conditions
Data Source
AI summary
Systems and methods for reducing phase delay variation impact are described. A microcontroller can receive a sequence of phase offsets determined by a slave device over time. The microcontroller can determine a weight vector based on a metric associated with the sequence of phase offsets. The microcontroller can adjust a set of filter coefficients based on the weight vector. The set of filter coefficients can be filter coefficients of a filter being implemented by the slave device to filter incoming packet data.