Coherent Receiver Impairment Monitoring via Delayed Waveform Correlation
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Solution Overview
Problem
Existing optical transmission networks face challenges in monitoring impairment across fiber links due to limited location flexibility of deployed optical performance monitors, leading to increased costs and inability to monitor every location effectively.
Innovation Solution
A method and device for monitoring impairment in optical signals using a coherent receiver, which involves obtaining a second received waveform with a relative delay, creating a template for nonlinear noise, and calculating correlation to estimate impairment at specific locations along the fiber link without requiring additional monitoring devices in the middle of the fiber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical performance monitors are deployed at multiple locations along the fiber link, then monitoring precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a template waveform that copies and represents the nonlinear noise characteristics at different fiber locations. By generating this template through digital signal processing from the received waveform, the system can monitor impairment at multiple locations without physically deploying monitors at each location, thus improving measurement precision while avoiding the complexity of multiple physical devices
Solution Approach 2:
The patent segments the fiber link into multiple monitoring locations by processing the waveform at different time delays. The received waveform is divided into multiple sub-waveforms with relative delays, and a template is generated for each segment location. This allows the single monitor to virtually monitor multiple locations along the fiber link, achieving location-resolved monitoring without additional hardware
2Measurement precision
If optical performance monitors are deployed at every location along the fiber link, then monitoring precision is improved, but cost increases
Solution Approach 1:
Instead of deploying physical monitors at every location, the patent creates a virtual template waveform that copies the nonlinear noise characteristics for each location. This template is generated through digital signal processing from a single received waveform, allowing the system to monitor impairment at multiple locations without the need for multiple physical monitors, thus reducing cost while maintaining comprehensive monitoring coverage
Solution Approach 2:
The single coherent receiver and signal processing system performs multiple functions: it monitors impairment at different locations, characterizes nonlinear noise, and generates templates for various fiber segments. This multi-functional approach replaces the need for multiple dedicated monitors at each location, reducing the total quantity of monitoring devices required while maintaining comprehensive monitoring precision
3Adaptability or versatility
If traditional monitoring methods are used, then device complexity is reduced, but location flexibility is lost
Solution Approach 1:
The patent implements dynamic waveform processing where the system can adaptively generate templates for different fiber locations by adjusting time delays and processing parameters. The signal processing system dynamically creates location-specific templates from the received waveform, allowing flexible monitoring at any location along the fiber link without requiring physical reconfiguration or additional hardware, thus achieving location flexibility while keeping device complexity manageable
Data Source
AI summary
A method for monitoring impairment includes: receiving a first received waveform sent by the coherent receiver; obtaining a second received waveform including a first sub-waveform and a second sub-waveform with a relative first delay therebetween according to the first received waveform; obtaining a template at a predetermined location on the fiber link according to the second received waveform, wherein the template is used for representing a nonlinear noise by a first sub-signal waveform and a second sub-signal waveform at the predetermined location that are respectively obtained from the first sub-waveform and the second sub-waveform and have the first delay therebetween; obtaining a correlation between the second received waveform and the template; changing a value of the first delay to obtain values of the correlation corresponding to different values of the first delay; and outputting a value of the first delay corresponding to a maximum value of the correlation as impairment estimation.