OSC Band Segmentation for Symmetric Time-Frequency Transfer
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Solution Overview
Problem
Current methods for high-precision time and frequency transfer over optical fiber networks face limitations due to asymmetry in transmission delays, compatibility issues with existing WDM networks, and high costs associated with dedicated fiber links, which restrict large-scale and high-coverage applications.
Innovation Solution
A system and method for fiber-optic time and frequency joint transmission using different sub-bands within a standard OSC band, allowing for simultaneous transmission of time frequency signals, optical supervisory signals, and communication data over the same optical fiber through CWDM modules in commercial WDM systems, ensuring bidirectional symmetry and reducing resource occupancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time and frequency signals are transmitted in different coarse wavelength division bands (1470 nm and 1490 nm) as in prior art, then bidirectional transmission can be achieved, but serious asymmetry of delays occurs and precision of time and frequency transfer is limited
Solution Approach 1:
The patent segments the OSC band into multiple sub-bands and assigns different sub-bands to forward and backward time frequency signals. This segmentation allows both signals to operate within the same coarse wavelength division band, ensuring symmetric transmission characteristics and eliminating the delay asymmetry problem that occurs when signals are transmitted in different coarse bands.
Solution Approach 2:
The patent changes the wavelength parameter by using closely spaced wavelengths within the same OSC sub-band for bidirectional transmission, rather than using widely separated coarse wavelength division bands. This parameter change ensures that both forward and backward signals experience similar transmission conditions, achieving symmetric delays and high precision time and frequency transfer.
2Reliability
If dedicated coarse wavelength division multiplexers are provided for each node to separate OSC band and communication band, then time frequency signals can be transmitted, but costs increase and existing commercial WDM networks are not compatible
Solution Approach 1:
The patent makes the existing CWDM modules in commercial WDM networks multi-functional by configuring them to handle both traditional OSC/communication signals and new time frequency signals. Instead of requiring dedicated multiplexers for each node, the existing infrastructure is utilized through proper wavelength allocation within the OSC band, reducing implementation costs and ensuring compatibility with existing networks.
Solution Approach 2:
The existing CWDM modules in the network self-serve the new time frequency transmission function through their inherent wavelength division capabilities. By allocating time frequency signals to specific sub-bands within the OSC band, the existing infrastructure automatically provides the necessary multiplexing and demultiplexing functions without requiring additional dedicated equipment at each node.
3Productivity
If coarse wavelength division bands are occupied for time frequency transmission, then time frequency signals can be transmitted over existing networks, but communication service wavelengths are constrained and services are interrupted
Solution Approach 1:
The patent segments the OSC band into multiple sub-bands and allocates specific sub-bands for time frequency signals while leaving other sub-bands available for communication services. This segmentation allows simultaneous operation of both time frequency transmission and communication services without wavelength conflicts, maintaining network productivity while preserving adaptability for future communication needs.
Solution Approach 2:
The patent applies local quality by assigning different wavelength characteristics to different functions within the same OSC band. Time frequency signals are assigned to specific sub-bands with appropriate wavelength properties, while communication services use other sub-bands, allowing each function to have optimized local wavelength characteristics without interfering with the other.
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
This approach enhances the precision of time and frequency transfer, improves wavelength resource utilization, and reduces implementation costs by integrating time frequency and data services without disrupting existing communication services or requiring replacement of CWDM modules.
Implementation Method 1
transmit a time frequency signal and an optical supervisory signal individually using different sub-bands within a standard OSC band in an optical communication network, and achieves joint transmission of the time frequency signal and the optical supervisory signal with optical communication data over the same optical fiber through CWDM modules
Data Source
AI summary
System and method for fiber-optic time frequency and data joint transmission, comprising local end, relay nodes, and remote end. In each local end, relay node, and remote end, multiplexing and demultiplexing of time frequency signals, optical supervisory signals, and optical communication data services are performed by CWDM modules and OSC-band wavelength multiplexer/demultiplexers, and processing (transmitting, relaying, receiving) is performed by corresponding processing modules for joint transmission. A sub-band of standard OSC band is used for transmitting time frequency signal so that transmission of optical supervisory signal is not influenced while no extra band resource is occupied with improved utilization of wavelength resources and reduced costs. Wavelengths of time and frequency transfer in both directions in sub-band of OSC band are flexibly selected and combined to meet different requirements; wavelengths are close or same so that bidirectional symmetry of the link is guaranteed to the maximum with improved precision.