Time Synchronization Accuracy via Timestamp Quality Filtering
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Solution Overview
Problem
Time synchronization between nodes in a network is often inaccurate due to fluctuations in network delay, jitter, and noise, especially when nodes are connected by different types of links and use varying timestamping methods.
Innovation Solution
The solution involves determining the reliability of timestamps by sharing and processing chain of quality information, which includes accuracy metrics of the upstream node's clock, timestamping method, and link type, to adjust filtering parameters and improve synchronization accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard time synchronization messages are exchanged between master and slave nodes, then time synchronization is achieved, but accuracy deteriorates due to network delay fluctuations, jitter, and noise
Solution Approach 1:
The system performs preliminary actions by collecting quality information about upstream nodes, links, and timestamping methods before time synchronization occurs. This quality information is used to pre-determine filtering parameters that will be applied to timestamps, allowing the system to prepare appropriate filtering strategies in advance based on expected signal quality conditions.
Solution Approach 2:
The filtering parameters are made dynamic rather than static. The system adjusts filtering parameters based on the determined quality information from different upstream nodes and link types. This allows the filtering mechanism to adapt its strength and characteristics dynamically according to the actual quality of incoming timestamps, improving accuracy under varying network conditions.
2Measurement precision
If filtering is applied to timestamps to improve accuracy, then time synchronization precision improves, but device complexity increases due to quality information processing
Solution Approach 1:
The quality information is segmented into distinct components: upstream node quality information, link quality information, and timestamping method quality information. This segmentation allows the system to process and evaluate different quality aspects independently, making the overall filtering mechanism more manageable and less complex than processing a monolithic quality metric.
Solution Approach 2:
The patent introduces an intermediary quality information structure that mediates between the raw timestamp data and the filtering operation. This quality information acts as an intermediary layer that carries metadata about upstream nodes, links, and timestamping methods, allowing the filtering mechanism to make informed decisions without directly processing all raw data, thereby reducing complexity.
3Reliability
If quality information from multiple upstream nodes is collected, then timestamp reliability determination improves, but information processing time increases
Solution Approach 1:
The system extracts only the essential quality information needed for reliability determination from multiple upstream nodes, rather than processing all available data. By taking out and focusing on critical quality metrics related to upstream nodes, links, and timestamping methods, the system achieves reliable timestamp verification without the overhead of processing redundant or less relevant information.
Data Source
AI summary
In a time synchronization process, chain of quality information is provided between interconnected nodes, the chain of quality information relating to information regarding accuracy of a clock, a type of timestamping used by a node, a type of link over which a timestamp is provided, and a clock drift parameter indicating the drift characteristics of the clock. Based on the chain of quality information, parameters are determined for a filter that is applied to a sequence of timestamps in order to remove noise from the timestamps, thereby improving accuracy of the time synchronization process.