Optical Receiver Equalization Using Pattern-Dependent Error Counts
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Solution Overview
Problem
Existing optical transmission networks face challenges in accurately adjusting eye pattern thresholds and sampling times due to signal distortions caused by intersymbol interference, chromatic dispersion, and polarization mode dispersion, leading to increased bit error rates and reduced dispersion tolerance.
Innovation Solution
A data recovery system in an optical receiver that accumulates pattern-dependent bit error counts to adjust threshold and phase settings for equalizers, reducing the need for dispersion compensating fiber and enhancing tolerance to chromatic dispersion, thereby improving chip yield and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional error correction methods are used, then bit error rate correction is achieved, but dispersion tolerance is limited and requires expensive dispersion compensating fiber
Solution Approach 1:
The patent employs feedback mechanisms where error counts from pattern-dependent error correction are used to dynamically adjust equalizer parameters. The system continuously monitors error patterns and feeds this information back to modify the equalization process, thereby improving both BER correction and dispersion tolerance simultaneously
Solution Approach 2:
The invention changes the parameters of the equalizer based on pattern-dependent error counts. By dynamically adjusting equalizer coefficients and thresholds according to observed error patterns, the system adapts to different dispersion conditions without requiring physical dispersion compensating fiber
2Adaptability or versatility
If pattern-dependent error correction is implemented, then dispersion tolerance increases, but system complexity increases
Solution Approach 1:
The patent segments the error correction process into pattern-dependent categories. Instead of treating all errors uniformly, the system identifies and corrects errors based on specific patterns, allowing for more targeted and efficient correction that improves dispersion tolerance without proportionally increasing overall system complexity
3Measurement precision
If equalizer parameters are dynamically adjusted, then data recovery accuracy improves, but processing time increases
Solution Approach 1:
The system performs preliminary equalization using initial parameters, then uses error pattern analysis to make incremental adjustments. This preliminary action approach allows the system to achieve good data recovery accuracy quickly, with subsequent refinements requiring minimal additional processing time
Data Source
AI summary
An optical transmission network includes an optical transmitter photonic integrated circuit (TxPIC) chip, utilized in an optical transmitter and has a plurality of monolithic modulated sources integrated for multiple signal channels on the same semiconductor chip is provided with channel equalization at the optical receiver side of the network that permits one or more such integrated modulated sources in the TxPIC chip to be out of specification thereby increasing the chip yield and reducing manufacturing costs in the deployment of such TxPIC chips. FEC error counts at the FEC decoder on the optical receiver side of the network includes counters that accumulate a plurality of bit pattern-dependent error counts based on different N-bit patterns in the received data bit stream. The accumulated counts of different N-bit patterns are utilized to provide for corrections to threshold and phase relative to the bit eye pattern as well as provided for weight coefficients for the optical receiver equalization system. The deployment of this type of equalization in a digital OEO REGEN network substantially reduces, if not eliminates, the need for dispersion compensating fiber (DCF) or EDFAs in an optical link of the network and enhances the optical receiver tolerance to chromatic dispersion (CD) so that an increase in chip yield is realized for TxPIC chips not operating with acceptable operational parameters, particularly with a desired frequency chirp parameter relative to at least one of the TxPIC modulated sources.