Clock Processing Device Asymmetric One-Way Delay Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current time synchronization methods, such as NTP and PTP, face inaccuracies in calculating one-way delays when they differ between upstream and downstream directions, leading to incorrect time differences, especially in PTP where precision is critical.
Innovation Solution
A clock processing device and program that calculate one-way delays by determining round-trip delays, temporary delay bases, and delay differences, allowing for accurate estimation of one-way delays even in cases of differing upstream and downstream delays through a combination of clock units, communication units, and delay calculation units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the T1-T4 method is used to calculate one-way delay, then the calculation can be performed immediately after t4 is acquired, but the time difference becomes incorrect when upstream and downstream one-way delays are different
Solution Approach 1:
The patent segments the round-trip delay calculation into separate upstream and downstream one-way delay calculations. By calculating each direction independently using the same T1-T4 method, then combining them to get the total round-trip delay, the system maintains calculation efficiency while achieving accurate one-way delay measurement even when upstream and downstream delays differ.
Solution Approach 2:
The patent explicitly handles the asymmetric case where upstream and downstream one-way delays are different. Instead of assuming symmetry and using a simple average, the system calculates both directions separately and uses the appropriate values to compute accurate time differences, thereby resolving the contradiction between simple calculation and accurate measurement.
2Device complexity
If the T1-T4 method assumes equal upstream and downstream one-way delays, then the calculation is simplified, but the time difference is incorrect in networks with asymmetric delays
Solution Approach 1:
The patent divides the single one-way delay calculation into two separate calculations (upstream and downstream), each using the simplified T1-T4 method. This segmentation allows the system to maintain calculation simplicity for each individual direction while achieving reliable overall accuracy by combining the results.
Solution Approach 2:
The patent changes the approach from assuming equal upstream and downstream delays to calculating them separately as independent parameters. By treating upstream and downstream delays as distinct parameters and calculating them independently, the system achieves reliable time difference accuracy without significantly increasing overall calculation complexity.
3Productivity
If NTP accuracy of 1 millisecond is assumed, then calculation errors are negligible for most cases, but the precision is insufficient for PTP requirements
Solution Approach 1:
The patent performs preliminary calculations of upstream and downstream one-way delays separately before computing the final time difference. By preparing these individual delay values in advance using the T1-T4 method, the system enables high-precision time difference calculation without sacrificing synchronization speed, as the preliminary calculations can be performed efficiently.
Solution Approach 2:
The patent segments the one-way delay measurement into upstream and downstream components, allowing each to be calculated independently with high precision. This segmentation enables the system to achieve PTP-level precision (sub-millisecond accuracy) while maintaining NTP-like calculation efficiency, as each segmented calculation can use optimized algorithms.
Data Source
AI summary
In a clock processing device, a delay difference calculation unit calculates a first one-way delay difference that is a difference between the first one-way delay of a target message combination and a first temporary delay base, and calculates a second one-way delay difference that is a difference between the second one-way delay of the target message combination and a second temporary delay base. A reference value calculation unit calculates a reference values of a first one-way delay from the calculated first one-way delay difference and the first temporary delay base and calculate a reference value of the second one-way delay from the calculated second one-way delay difference and the second temporary delay base. An estimation unit calculates the first one-way delay from the round-trip delay of the target message combination and from a ratio determined according to the first one-way delay reference value and the second one-way delay reference value.