Histogram-Based Chromatic Dispersion Estimation in Optical Receivers
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Solution Overview
Problem
In coherent optical communication, accurately estimating chromatic dispersion in optical signals is challenging due to its impact on signal quality, particularly in compensating for material and waveguide dispersion, which broadens pulses and scrambles signal polarization during transmission.
Innovation Solution
A histogram-based method iteratively adjusts dispersion compensation coefficients of filters in the optical receiver, generating and evaluating amplitude histograms to estimate chromatic dispersion, using a cost function to determine optimal compensation levels, ensuring accurate signal recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional chromatic dispersion estimation methods are used, then the estimation process is straightforward, but the accuracy of chromatic dispersion estimation deteriorates due to pulse broadening and polarization scrambling
Solution Approach 1:
The patent applies dynamics by making the histogram evaluation adaptive and iterative. The system dynamically adjusts the chromatic dispersion compensation filter coefficients through multiple iterations, where each iteration refines the histogram-based estimation. This dynamic approach allows the system to adapt to varying signal conditions and progressively improve estimation accuracy despite pulse broadening and polarization scrambling effects.
Solution Approach 2:
The patent implements feedback through the iterative histogram evaluation process. The histogram of the compensated signal is continuously evaluated, and the results feed back into adjusting the chromatic dispersion compensation filter coefficients. This feedback loop enables the system to self-correct and converge on accurate chromatic dispersion estimation by using the histogram characteristics as a performance metric that guides further compensation adjustments.
2Measurement precision
If iterative adjustment of dispersion compensation coefficients is performed, then chromatic dispersion compensation accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent extracts the essential chromatic dispersion information by focusing specifically on the histogram characteristics of the compensated signal. Instead of analyzing the entire complex signal structure, the method extracts only the amplitude distribution statistics through histogram generation. This extraction approach simplifies the computational burden while retaining the critical information needed for accurate chromatic dispersion estimation, as the histogram captures the essential pulse broadening effects without requiring full signal reconstruction.
Data Source
AI summary
Techniques are provided for estimation of the chromatic dispersion (CD) in an optical signal received by an optical receiver. The techniques involve iteratively adjusting dispersion compensation coefficients of one or more filters configured to compensate for the CD in the received optical signal. At each iteration of the dispersion compensation coefficient adjustment, electrical domain signals are filtered to generate digitally-filtered signals. The electrical domain signals are generated based on the received optical signal. Also at each iteration of the dispersion compensation coefficient adjustment, an amplitude histogram of the digitally-filtered signals is generated. The amplitude histograms generated at each iteration are evaluated to generate an estimate of the chromatic dispersion in the received optical signal.