OTN Clock Recovery Using Accumulated Phase Difference Data
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Solution Overview
Problem
Existing optical transport network (OTN) systems face challenges in accurately recovering clock synchronization frequencies due to high complexity and overhead in processing reference clocks across multiple devices, leading to inaccuracies in clock recovery.
Innovation Solution
A method for clock recovery that involves obtaining phase difference information from OTN frames, adjusting the reference clock based on accumulated phase differences, and using a constant-temperature crystal oscillator to ensure stability, thereby reducing complexity and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reference clocks of second OTN frames are extracted and processed from each device in the system, then clock recovery can be performed, but the complexity and overhead of clock recovery increase significantly
Solution Approach 1:
The patent extracts only the necessary phase difference information from the OTN frames rather than processing complete reference clocks from each device. By extracting only the phase difference data in the overhead area, the system reduces processing complexity while maintaining sufficient information for accurate clock recovery at the destination device.
Solution Approach 2:
The patent merges the phase difference information from multiple upstream devices into a single accumulated value that is transmitted in the OTN frame overhead. This consolidation approach allows the destination device to recover the server layer clock by processing a single aggregated phase difference value rather than handling multiple separate reference clocks, thereby reducing processing complexity.
2Measurement precision
If phase difference information is accumulated from multiple upstream devices, then clock recovery accuracy improves, but processing time and computational load increase
Solution Approach 1:
The patent performs preliminary accumulation of phase difference information at intermediate devices along the signal path. By the time the OTN frame reaches the destination device, the phase difference information from multiple upstream devices has already been aggregated, so the destination device only needs to process this pre-accumulated data rather than collecting and processing multiple separate measurements, thereby reducing processing time.
3Stability of the object's composition
If a constant-temperature crystal oscillator is used for reference clock, then clock stability improves, but device cost and complexity increase
Solution Approach 1:
The patent introduces a constant-temperature crystal oscillator as an intermediary reference clock source that provides stable timing information to the destination device. This intermediary reference clock enables accurate phase difference measurement and clock recovery without requiring each individual device to have its own highly stable oscillator, thereby reducing overall system complexity while maintaining stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enhances the accuracy of clock recovery, reducing errors to less than 40 nanoseconds and improving system performance by eliminating instantaneous phase errors and jitter.
Implementation Method 1
using a constant-temperature crystal oscillator to ensure stability
Data Source
AI summary
A method, an apparatus, and a system for clock recovery may be used in an optical transport network (OTN). The method includes: receiving a first optical transport network OTN frame data stream, obtaining, from the first OTN frame data stream, a server layer clock and phase difference information carried in a second OTN frame, and adjusting a reference clock of the second OTN frame based on the server layer clock and the phase difference information, where the reference clock of the second OTN frame is used to recover a clock of the second OTN frame.