Optical Pre-emphasis Power Deviation Control in Meshed Networks
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Solution Overview
Problem
Existing methods for optimizing per-channel pre-emphasis in optical multiplexed sections, such as Automatic Pre-emphasis Adjustment (APA) and Enhanced Automatic Power Equalization (APE), are inadequate for meshed networks as they rely on unreliable quality of transmission indicators and fail to account for amplifier and span power heterogeneity, leading to suboptimal power profiles.
Innovation Solution
A method that measures output power, determines predicted output power using design characteristics, calculates signal-to-noise ratio and nonlinear phase shift deviations, and adjusts the launch power profile to equally reduce these deviations across spans, allowing for precise pre-emphasis without relying on Bit Error Rate (BER) measurements or additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Automatic Pre-emphasis Adjustment (APA) is used to optimize per-channel pre-emphasis, then BER optimization is improved, but device complexity increases and it becomes suitable only for point-to-point routes
Solution Approach 1:
The patent extracts the essential function of BER measurement and replaces it with OCM-based power deviation measurement. By removing the dependency on BER feedback mechanisms, the system achieves pre-emphasis optimization without the complex closed-loop algorithms required by APA, thus reducing device complexity while maintaining optimization capability.
Solution Approach 2:
The patent introduces an Optical Channel Monitor (OCM) as an intermediary device to measure per-channel power deviations. This intermediary replaces the need for direct BER measurement and feedback mechanisms, enabling pre-emphasis optimization through power-based metrics that are easier to measure and process in meshed network environments.
2Stability of the object's composition
If Enhanced Automatic Power Equalization (APE) is used to equalize power of all channels, then flat launch is improved, but measurement reliability decreases due to reliance on OCM instead of BER
Solution Approach 1:
The patent changes the measurement parameter from BER (which requires complex feedback and is unreliable in meshed networks) to per-channel power deviation measured by OCM. This parameter change enables flat launch optimization while improving measurement reliability, as power measurements are more stable and easier to obtain in complex network topologies.
3Ease of manufacture
If pre-emphasis power is set to half of the measured per-channel power deviation, then implementation is simplified, but power optimization accuracy deteriorates due to ignoring amplifier and span heterogeneity
Solution Approach 1:
The patent applies local quality by calculating pre-emphasis power individually for each channel based on its specific power deviation and the heterogeneity characteristics of its corresponding span. Instead of using a uniform half-deviation rule, the system tailors the pre-emphasis power to match the local conditions of each channel-span combination, significantly improving optimization accuracy while maintaining implementable complexity.
Data Source
AI summary
An apparatus and method of pre-emphasising a launch power profile of a section in an optical network is provided. The method comprises measuring the output power at the output of the section, determining the predicted output power associated with a flat launch power profile using design characteristics of the section and determining the total power deviation between the measured output power and the predicted output power. Also, the method comprises determining the signal to noise ratio deviation and the nonlinear phase shift deviation as a function of the total power deviation, and pre-emphasising the launch power profile based on a function of the calculated signal to noise ratio deviations of each span and the calculated nonlinear phase shift deviations of each span, such that the sum of the nonlinear phase shift deviations and the sum of the signal to noise ratio deviations of each channel are reduced by an equal amount.