Adaptive Equalizer Tap Coefficient Correction Using Fluctuation Centers
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Solution Overview
Problem
Existing tap coefficient correction methods in adaptive equalizers for digital coherent receivers fail to maximize correction effects, leading to increased differential group delay resistance and bit errors, as they rely on instantaneous gravity center values rather than fluctuation centers for correction.
Innovation Solution
The method involves calculating correction reference gravity centers based on synchronization symbol differences and delay amounts, shifting entire tap coefficients to align with the tap center, using fluctuation centers as references to accurately correct tap coefficients in adaptive equalizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If instantaneous gravity center values are used for tap coefficient correction, then the correction process is simple, but the correction effect is insufficient leading to increased bit errors
Solution Approach 1:
The patent applies preliminary action by calculating the fluctuation center of tap coefficients in advance before correction is needed. The fluctuation center is computed based on historical tap coefficient data, and this pre-calculated reference value is then used for correction, avoiding the need for complex real-time analysis while improving correction accuracy and reducing bit errors.
2Measurement precision
If fluctuation centers are used as correction references, then correction accuracy improves and bit errors decrease, but calculation complexity increases
Solution Approach 1:
The patent applies self-service by having the system calculate its own fluctuation center using its existing tap coefficient data. The adaptive equalizer inherently generates the tap coefficients, and the correction apparatus uses these same coefficients to compute the fluctuation center, eliminating the need for external or additional complex measurement systems while achieving improved correction accuracy.
3Reliability
If tap coefficients are shifted to align gravity center with tap center, then differential group delay resistance improves, but the correction may not be optimal without proper reference
Solution Approach 1:
The patent applies feedback by continuously monitoring the tap coefficients and using their fluctuation characteristics to determine the optimal correction amount. The fluctuation center calculation provides feedback about the tap coefficient distribution pattern, which then guides the shifting operation to achieve optimal alignment with the tap center, maximizing differential group delay resistance while maintaining precision.
Data Source
AI summary
A method of tap coefficient correction includes: obtaining a synchronization symbol difference between a first polarization and a second polarization orthogonal to the first polarization; obtaining a delay amount of each of the first polarization and the second polarization in an adaptive equalizer; calculating, in a case where a horizontal axis represents a tap number and a vertical axis represents a tap coefficient and a tap number or a nearest tap number with which an area of a drawn figure is halved is set as a gravity center of tap coefficients, a correction reference gravity center of the tap coefficients set in the adaptive equalizer, based on the synchronization symbol difference and the delay amount; and performing a correction of shifting an entire tap coefficients in units of symbol to cause the correction reference gravity center to be closest to a tap center.