OTN Time Synchronization via Timestamp Correction
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Solution Overview
Problem
In Optical Transport Networks (OTNs), high-precision IEEE1588 time synchronization is compromised due to unsymmetrical and unstable transmission delays, which are inherent in OTN framing and mapping processes.
Innovation Solution
A method involving a master and slave device exchange time synchronization messages with timestamp corrections to account for delay asymmetry, allowing for precise synchronization by generating and correcting timestamps (T1, T2, T3, T4) within the OTN framework, thereby eliminating the impact of asymmetrical delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OTN framing and mapping processes are used, then service transmission capability is improved, but transmission delay symmetry and stability deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-calculating and recording the transmission delays in both forward and reverse directions during the synchronization message exchange process. The master device records the time difference between sending the synchronization message and receiving the delay message, while the slave device records the time difference between receiving the synchronization message and sending the delay message. These pre-recorded delay values are then used to compensate for asymmetry in subsequent synchronization calculations, thereby resolving the delay symmetry issue while maintaining OTN framing capabilities
Solution Approach 2:
The patent implements feedback by having the slave device send a delay message back to the master device containing timestamp information about when it received the synchronization message. This feedback loop enables both devices to calculate their respective transmission delays and use this information to compensate for asymmetry. The feedback mechanism allows the system to adapt to varying transmission conditions while maintaining synchronization precision
2Quantity of substance
If OTN encapsulation and mapping are applied, then service bearing capacity is improved, but time synchronization precision deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-recording the exact timestamps when synchronization messages enter and leave the OTN framing system at both master and slave devices. By capturing these timestamps before any OTN processing occurs, the system can calculate the actual transmission delay through the OTN network. This preliminary timestamp recording allows the system to compensate for the precision loss caused by OTN encapsulation and mapping operations
Solution Approach 2:
The patent implements feedback by having the slave device return its received timestamp and local timestamp to the master device in a delay message. This feedback enables the master device to calculate the round-trip delay through the OTN network and use this information to correct synchronization timing. The feedback mechanism compensates for the precision degradation introduced by OTN processing by providing actual measured delay data
Data Source
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AI summary
A method, device, system, and computer storage medium for implementing time synchronization in an OTN are provided. The method includes: a master device generates a time synchronization message, performs a first correction on a correction domain of the time synchronization message, and sends it including a first timestamp T1 to a slave device. The slave device performs a second correction on the correction domain of the time synchronization message, adds a second timestamp T2, generates a delay request message, performs a third correction on the correction domain of the delay request message, and sends to the master device the delay request message including a third timestamp T3. The master device performs a fourth correction on the correction domain of the delay request message, adds a fourth timestamp T4, sends to the slave device a delay response message including the correction domain of the delay request message subjected to the fourth correction and the fourth timestamp T4. The slave device performs time synchronization with the master device according to T1, T2, T3, T4 and the correction domains of the time synchronization message and the delay request message.