Asymmetric Delay Correction in Relay Time-Synchronization Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In time-synchronization systems, asymmetric delays in transmission lines lead to inaccurate delay information transmission, affecting the synchronization accuracy between master and slave apparatuses using Precision Time Protocol (PTP).
Innovation Solution
A time-synchronization system where a second relay apparatus transmits information about the difference between its own time information and that from a time-synchronization source to a first relay apparatus, allowing the first relay apparatus to correct its time information obtained from a master apparatus, thereby improving synchronization accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the REC transmits a time equivalent to a half of the delay time in a round trip to the other REC as the delay time for the correction, then the time-synchronization can be performed, but the synchronization accuracy deteriorates when asymmetric delay occurs in the transmission line
Solution Approach 1:
The patent implements a feedback mechanism where the second REC measures the actual asymmetric delay by comparing its local time with the time from the time-synchronization source, then feeds back this delay difference information to the first REC. The first REC uses this feedback to correct its time calculation, thereby resolving the inaccuracy caused by asymmetric delays in the transmission line.
Solution Approach 2:
The second REC acts as an intermediary that measures the asymmetric delay caused by the transmission line and communicates this measurement to the first REC. This intermediary role allows the system to account for transmission line effects without requiring the first REC to directly measure or compensate for the asymmetric delay.
2Adaptability or versatility
If the REC operates as a boundary clock to perform time-synchronization with both master and slave apparatuses, then the time-synchronization function is enhanced, but the device complexity increases
Solution Approach 1:
The patent combines multiple time-synchronization functions into a single boundary clock apparatus. The first REC performs time-synchronization with the master apparatus, while the second REC performs time-synchronization with both the first REC and the time-synchronization source. This merging of functions allows the system to handle asymmetric delays effectively while maintaining a relatively simple overall structure.
Data Source
AI summary
A time-synchronization system according to the present disclosure includes a relay apparatus (10) configured to perform time-synchronization with a master apparatus (30) through a transmission system of which a transmission delay changes depending on a transmission direction, and a relay apparatus (20) configured to perform time-synchronization with the relay apparatus (10), in which the relay apparatus (20) transmits information about a difference between first time information obtained by performing time-synchronization with the relay apparatus (10) and second time information obtained from a time-synchronization source to the relay apparatus (10), and the relay apparatus (10) corrects third time information obtained by performing time-synchronization with the master apparatus (30) by using the information about the difference, and performs time-synchronization with a slave apparatus (50) by using the corrected third time information.