Globally Coherent Timestamps Through Multi-Reference Delay Compensation
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Solution Overview
Problem
Distributed systems face challenges in achieving synchronized timestamps without incurring network delays and relying on unreliable time masters, which can lead to inaccurate event ordering and causality issues.
Innovation Solution
Implementing a method that uses a plurality of time references, including GPS and atomic clocks, to track, calculate, and record time data, compensating for transmission delays and adjusting local timestamps to ensure accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If NTP service is used to synchronize clocks by querying time masters, then time synchronization is achieved, but network delays and transmission asymmetry cause measurement uncertainty and reduce reliability
Solution Approach 1:
The patent combines multiple time references (GPS, atomic clocks, NTP servers) into a unified time synchronization system. Instead of relying on a single time master, the system aggregates time data from multiple sources and uses statistical methods to determine the most accurate time, thereby improving both precision and reliability
Solution Approach 2:
The system continuously monitors time offsets between local clocks and reference time sources, using this feedback to adjust and discipline local clocks. The feedback loop includes detecting transmission delays, calculating time offsets, and adjusting clock rates to maintain synchronization, thereby compensating for network variability and improving measurement accuracy
2Measurement precision
If explicit synchronization with time masters is performed, then clock synchronization is achieved, but network delays and system overloads increase time synchronization error
Solution Approach 1:
The system performs preliminary measurements of transmission delays by sending test packets to time references and recording round-trip times. These preliminary delay measurements are stored and used to compensate for future time synchronization calculations, reducing the impact of network variability on timestamp accuracy without requiring real-time synchronization delays
Solution Approach 2:
The patent replaces the mechanical NTP synchronization protocol with a software-based time stamping system that uses pre-measured delay values. Instead of relying on real-time network round-trip measurements, the system uses stored delay profiles and statistical analysis to calculate accurate time offsets, thereby eliminating the need for repeated network synchronization transactions
3Reliability
If multiple time references are queried to improve reliability, then trustworthiness of time data increases, but system complexity and processing overhead increase
Solution Approach 1:
The system segments time references into different categories (GPS, atomic clocks, NTP servers) and assigns different weights and trust levels to each type. This segmentation allows the system to selectively query appropriate time sources based on availability and reliability requirements, reducing unnecessary processing while maintaining high confidence in time data
Solution Approach 2:
The system dynamically adjusts parameters such as the number of time references queried, the weighting factors applied to different sources, and the threshold for accepting time offsets based on observed network conditions and time data quality. This adaptive parameter adjustment optimizes the balance between reliability and system complexity in different operating conditions
Data Source
AI summary
The present technology proposes techniques for generating globally coherent timestamps. This technology may allow distributed systems to causally order transactions without incurring various types of communication delays inherent in explicit synchronization. By globally deploying a number of time masters that are based on various types of time references, the time masters may serve as primary time references. Through an interactive interface, the techniques may track, calculate and record data relative to each time master thus providing the distributed systems with causal timestamps.