Chromatic Dispersion Calculation Using Threshold Processing
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Solution Overview
Problem
Blind chromatic dispersion estimation using delay-tap sampling methods is inaccurate for signals with high peak-to-average power ratio (PAPR), as the evaluation function tends to be unstable due to abrupt power fluctuations, making it difficult to determine the correct dispersion compensation amount.
Innovation Solution
A chromatic dispersion amount calculation apparatus and method that apply threshold processing to the power values of signal and delayed signal samples, using a computation unit to evaluate the chromatic dispersion amount by computing an evaluation function based on the difference between signal and delayed signal powers, and determining computation availability based on threshold conditions to stabilize the estimation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If blind chromatic dispersion estimation using delay-tap sampling method is applied to signals with high PAPR, then the estimation can be performed without known signals, but the evaluation function becomes unstable due to abrupt power fluctuations, deteriorating estimation accuracy
Solution Approach 1:
The patent changes the parameter selection criterion from using all signal samples to using only samples where the signal power exceeds a predetermined threshold. This parameter change filters out samples with abrupt power fluctuations characteristic of high PAPR signals, stabilizing the evaluation function and improving dispersion estimation accuracy while maintaining the simplicity of the blind estimation method
Solution Approach 2:
The patent applies different processing to different portions of the signal samples by introducing a threshold condition. Instead of uniformly processing all samples, it selectively processes only those samples whose power exceeds the threshold, creating a quality-based segmentation that improves the reliability of the evaluation function for high PAPR signals
Data Source
AI summary
A computation unit uses an assumed chromatic dispersion amount to compensate for dispersion of a coherently received optical signal and performs arithmetic of a signal power of the optical signal that is dispersion compensated. The computation unit performs computation of an evaluation function when a signal power and a delayed signal power obtained by applying a predetermined delay to the signal power satisfy a threshold condition. The evaluation function is a function for evaluating whether the assumed chromatic dispersion amount is a chromatic dispersion amount of the optical signal using the difference between the signal power and the delayed signal power. The chromatic dispersion amount calculation unit calculates a chromatic dispersion amount of the optical signal based on the computation result of the evaluation function by the computation unit when each of a plurality of different assumed chromatic dispersion amounts is used.