Coherent Receiver gOSNR Monitoring via Noise Correlation
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Solution Overview
Problem
Existing optical networks face limitations in location flexibility for monitoring generalized optical signal-to-noise ratio (gOSNR), as conventional methods only account for amplified spontaneous emission (ASE) noise, neglecting self-phase modulation (SPM) and cross-phase modulation (XPM) noise, which affect bit error rate (BER).
Innovation Solution
A method and device for monitoring gOSNR that utilizes correlation calculations between noise and templates to account for both ASE and nonlinear noises, enabling flexible monitoring at any location along the fiber link using a coherent receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional OSNR monitoring methods are used, then the monitoring setup is simple, but the measurement precision is insufficient because it only accounts for ASE noise and neglects nonlinear noises (SPM, XPM) that affect BER
Solution Approach 1:
The patent introduces correlation calculation as an intermediary mathematical tool to extract noise characteristics from the received waveform. By computing the correlation between the noise part and templates representing different noise types (ASE, SPM, XPM), the system can precisely measure gOSNR without requiring complex physical monitoring equipment at multiple locations. This intermediary calculation enables comprehensive noise accounting while keeping the overall system relatively simple.
Solution Approach 2:
The patent replaces traditional mechanical/optical monitoring methods (which would require multiple physical OPMs deployed at different locations along the fiber link) with a digital signal processing approach. The coherent receiver captures the optical signal, converts it to electrical signals, and then digital processing algorithms extract noise characteristics through correlation calculations. This substitution of mechanical monitoring with electronic/digital measurement achieves higher precision while reducing physical device complexity.
2Adaptability or versatility
If multiple optical performance monitors are deployed to monitor gOSNR at different locations, then the location flexibility and measurement precision improve, but the device complexity and cost increase
Solution Approach 1:
The patent makes the single coherent receiver at the receiving end perform multiple functions: it not only detects the optical signal but also extracts comprehensive noise characteristics (ASE, SPM, XPM) and calculates gOSNR at any location along the fiber link through correlation calculations. This universal approach allows one device to provide monitoring capabilities that would traditionally require multiple dedicated monitors distributed throughout the network, thereby improving location flexibility without increasing device complexity.
Solution Approach 2:
The patent creates a digital copy or representation of the noise characteristics and signal properties through correlation calculations with templates. Instead of physically monitoring at multiple locations, the system creates mathematical models (copies) of the signal and noise at different positions along the fiber link by processing the received waveform. This copying approach enables virtual monitoring at any location using a single physical receiver, improving adaptability while reducing hardware complexity.
3Reliability
If gOSNR monitoring is implemented to account for all noise sources, then the BER performance improves, but the difficulty of detecting and measuring increases
Solution Approach 1:
The patent segments the noise into distinct components (ASE noise, SPM noise, XPM noise) by using different templates for correlation calculation. Each noise type is represented by a specific template that captures its characteristic properties. By segmenting the noise analysis this way, the system can detect and measure each noise component separately through correlation calculations, making the complex task of measuring all noise sources more manageable and systematic, thereby improving BER performance without overwhelming measurement difficulty.
Data Source
AI summary
A method for monitoring generalized optical signal-to-noise ratio (gOSNR) is provided, which is applied to monitoring of an optical signal received by a coherent receiver through a fiber link. The method includes: obtaining a first received waveform; obtaining a signal part of the first received waveform; obtaining a noise part of the first received waveform according to the signal part and the first received waveform; obtaining a first correlation between the noise part and a first template at a predetermined location on the fiber link, the first correlation indicating a signal power at the predetermined location; obtaining a second correlation between the noise part and a second template at the predetermined location on the fiber link, the second correlation indicating a signal power and noise power at the predetermined location; and obtaining gOSNR at the predetermined location according to the first correlation and the second correlation.