Adaptive Equalization for Polarization Fluctuation and IQ Distortion
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Solution Overview
Problem
Existing adaptive technologies fail to efficiently compensate for rapid dynamic polarization fluctuations and IQ waveform distortion in optical transmission systems.
Innovation Solution
A signal processing device, including a first adaptive filter and a degree-of-freedom separation adaptive equalization unit, configured to perform adaptive equalization process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the internal degree of freedom of the adaptive filter is increased to compensate for IQ waveform distortion, then the compensation capability for IQ waveform distortion is improved, but the followability to rapid dynamic polarization fluctuations deteriorates
Solution Approach 1:
The patent segments the adaptive filter into two independent filters: a batch adaptive filter for compensating IQ waveform distortion and a degree-of-freedom separation adaptive filter for tracking polarization fluctuations. This segmentation allows each filter to specialize in one function, enabling the degree-of-freedom separation filter to use a larger step size for rapid tracking without being constrained by the IQ compensation requirements.
Solution Approach 2:
The patent implements dynamic operation by allowing the degree-of-freedom separation adaptive filter to operate with a larger step size that can be adjusted based on the rate of polarization fluctuations. This dynamic adjustment enables the system to respond rapidly to polarization changes while the batch adaptive filter continuously updates IQ compensation parameters.
2Speed
If the step size is increased to follow rapid polarization fluctuations, then the followability to polarization state changes is improved, but the stability of filter operation deteriorates due to covariance matrix trace increase
Solution Approach 1:
The patent divides the equalization function into two separate filters, allowing the degree-of-freedom separation adaptive filter to independently manage polarization tracking with optimized step size. This segmentation isolates the stability constraints of the batch filter from the speed requirements of the polarization-tracking filter.
Solution Approach 2:
The patent changes the operational parameters of the two filters differently: the batch adaptive filter uses a smaller step size for stability during IQ compensation, while the degree-of-freedom separation adaptive filter uses a larger step size for rapid polarization tracking. This parameter differentiation resolves the contradiction between stability and speed.
3Device complexity
If a fixed value compensation is used for IQ waveform distortion, then the device complexity is reduced, but the adaptability to temperature changes and degradation over time deteriorates
Solution Approach 1:
The patent implements a dynamic compensation approach where the batch adaptive filter continuously updates its coefficients based on incoming signals, allowing the system to adapt to temperature changes and component degradation over time. This dynamic operation maintains high adaptability while keeping the overall architecture relatively simple.
Solution Approach 2:
The batch adaptive filter performs self-adjustment by automatically tracking and compensating for IQ waveform distortion variations caused by environmental changes and aging. This self-service capability eliminates the need for manual recalibration while maintaining compensation effectiveness.
Data Source
AI summary
Provided is a signal processing device including: a batch adaptive equalization unit configured to use a first adaptive filter to perform an equalization process of waveform distortion on each polarized digital signal obtained by performing analog-to-digital conversion on a polarization-multiplexed signal; a matrix conversion unit configured to acquire filter coefficients of the first adaptive filter from at least the batch adaptive equalization unit, and convert acquired the filter coefficients through matrix operation; a degree-of-freedom separation adaptive equalization unit configured to use a second adaptive filter including the filter coefficients converted by the matrix conversion unit to perform an equalization process of waveform distortion due to polarization state fluctuation in a transmission path on each polarized digital signal; and a switching control unit configured to select a signal equalized by the batch adaptive equalization unit or the degree-of-freedom separation adaptive equalization unit as a reception signal.