Nonlinear Impairment Calculation for Optical Fiber Links
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Solution Overview
Problem
Current methods for calculating nonlinear transmission impairment in optical fiber links are slow and resource-intensive, making them unsuitable for rapid calculations required in live network deployment, expansion, and maintenance.
Innovation Solution
A method and apparatus that determine intra-band and inter-band nonlinear noise factors, correcting them to calculate nonlinear noise using specific formulas, allowing for quick and accurate assessment of nonlinear transmission impairment in optical fiber links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If numerical methods are used to solve the nonlinear Schrodinger equation for calculating nonlinear transmission impairment, then calculation accuracy is improved, but calculation time and computer resource occupation increase significantly
Solution Approach 1:
The patent segments the optical fiber link into multiple spans, each with its own nonlinear noise characteristics. By dividing the total link into manageable segments and calculating nonlinear noise for each span separately using simplified formulas, the method achieves both accuracy and speed. Each span's nonlinear noise is calculated independently and then accumulated to get the total nonlinear noise, avoiding the need for solving the complex nonlinear Schrodinger equation for the entire link.
Solution Approach 2:
The patent changes the calculation parameters from solving the differential nonlinear Schrodinger equation to using closed-form formulas with key parameters such as span length, average optical power, and fiber nonlinear coefficient. This parameter-based approach transforms an intractable numerical problem into a series of simple calculations that can be performed rapidly while maintaining sufficient accuracy for practical engineering applications.
2Measurement precision
If numerical methods are used to solve the nonlinear Schrodinger equation, then calculation accuracy is improved, but occupation of computer resources increases
Solution Approach 1:
The patent extracts the essential factors influencing nonlinear noise (span length, optical power, nonlinear coefficient) from the complex nonlinear Schrodinger equation system. By taking out only the critical parameters and using them in simplified closed-form formulas, the method eliminates the need for resource-intensive numerical simulations while retaining the core physical insights needed for accurate nonlinear noise estimation.
Solution Approach 2:
The patent employs simple, computationally inexpensive formulas that can be calculated rapidly with minimal computer resources. These simplified calculation models act as disposable, low-cost alternatives to expensive numerical simulations, providing sufficient accuracy for network planning and optimization without requiring powerful computing infrastructure.
3Measurement precision
If conventional calculation methods are used, then accurate nonlinear impairment calculation is achieved, but calculation speed becomes too slow for live network operations
Solution Approach 1:
The patent performs preliminary calculations by pre-determining the nonlinear noise factors for each span based on basic link parameters (length, power, fiber characteristics). These preliminary results are then quickly combined to obtain the total nonlinear noise for the entire link. This preliminary action approach allows rapid recalculation when network parameters change, making it suitable for live network operations where quick re-evaluation is needed.
Solution Approach 2:
The patent transforms the calculation from solving complex differential equations to using parameter-based closed-form expressions. By changing the mathematical approach from numerical integration to direct parameter substitution, the calculation speed increases dramatically while maintaining engineering-level accuracy for nonlinear impairment assessment.
Data Source
Figure 1a~1b
Figure 2a
Figure 2b~3
AI summary
The present invention relates to the field of network communications and specifically discloses a method for calculating a nonlinear transmission impairment of an optical fiber link, including: determining that no pump channel exists in an optical fiber link, obtaining a factor of intra-band nonlinear noise that is in the optical fiber link and does not pass through an optical filter, and obtaining integral power in signal light bandwidth of a span in the optical fiber link; correcting the factor of intra-band nonlinear noise that does not pass through an optical filter, to obtain a factor of intra-band nonlinear noise of the span in the optical fiber link that passes through an optical filter; calculating nonlinear noise of the span in the optical fiber link; and obtaining total nonlinear noise of the optical fiber link according to the nonlinear noise of the span in the optical fiber link, and obtaining a nonlinear transmission impairment of the optical fiber link. Embodiments of the present invention further provide an apparatus for calculating a nonlinear transmission impairment of an optical fiber link.