Launch Power Assignment for Coupled Fiber Spans
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Solution Overview
Problem
Current methods for assigning launch powers in optical transmission systems fail to optimize signal quality across fiber spans with varying properties, leading to suboptimal performance due to tradeoffs between ASE noise and nonlinear effects, especially in networks with mixed fiber types and lengths.
Innovation Solution
Decoupling amplifier properties from fiber span properties and using an iteration algorithm to determine optimum launch powers based on physical parameters, such as noise figures and fiber characteristics, to maximize system margin and signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If channel power is increased to reduce ASE noise power ratio, then the ratio of ASE noise power to signal power is reduced, but nonlinear distortions induced by fiber effects are enhanced
Solution Approach 1:
The patent applies local quality by assigning different launch powers to different fiber spans based on their individual characteristics. Instead of using a uniform launch power across all spans, the system calculates and applies span-specific launch powers that account for variations in fiber properties, lengths, and amplifier characteristics. This localized power assignment optimizes signal quality for each span while minimizing nonlinear distortions specific to that span's conditions.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the launch power parameter for each fiber span based on calculated optimal values. The system modifies the launch power parameter individually for each span rather than maintaining a fixed or uniform value, thereby adapting to varying fiber and amplifier characteristics across the transmission link.
2Ease of operation
If a common launch power is set for all spans, then the configuration is simple, but optimization is suboptimal for spans with varying properties such as attenuation and length
Solution Approach 1:
The patent applies segmentation by dividing the optical transmission system into individual fiber span segments, each with its own launch power setting. Instead of treating the entire link as a single unit with uniform power, the system segments the transmission path and assigns optimized power levels to each span based on its specific characteristics, thereby improving overall signal quality while maintaining manageable configuration complexity.
3Reliability
If feedback method is used to optimize common power, then optimum performance can be achieved for equal span lengths, but convergence problems occur getting stuck in local maxima for un-equal span lengths
Solution Approach 1:
The patent implements preliminary action by pre-calculating the optimal launch power for each fiber span using analytical models that incorporate fiber and amplifier characteristics. Rather than relying on iterative feedback methods that may converge to local maxima, the system performs preliminary optimization calculations based on physical parameters, thereby avoiding convergence issues while achieving optimal performance for unequal span lengths.
Data Source
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AI summary
The invention relates to a method (300) for assigning launch powers (Pi) to an arrangement of physically coupled dispersion uncompensated fiber spans (100) transmitting an optical channel, wherein each fiber span (100) comprises an optical amplifier (105), the method (300) comprising: decoupling (101) operation of the optical amplifiers (105) from the physical coupling of the fiber spans (100); and determining (103) for each of the fiber spans (100) a launch power (Pi) based on physical parameters of the corresponding fiber span (100).