Nonlinear Damage Compensation in Coherent Light Systems

Solution Overview

Problem

Conventional coherent-light communication systems face challenges in accurately compensating nonlinear damage due to Self-Phase Modulation (SPM) and intra-channel nonlinearity, requiring multiple stages of digital Back-Propagation units which increase complexity and reduce effectiveness.

Innovation Solution

A time domain and polarization combined processing method and apparatus that calculates additive interference across stages and subtracts it from input signals, reducing the number of stages needed for nonlinear damage compensation, utilizing an additive parameter calculating unit, delaying unit, and subtracting unit to achieve improved performance with fewer stages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple stages of digital Back-Propagation units are used to compensate nonlinear damage, then compensation accuracy is improved, but device complexity increases

Engineering Contradiction:

Improvenonlinear damage compensation accuracyVSAvoidnumber of BP unit stages

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the nonlinear damage compensation process into two distinct parts: (1) additive interference calculation based on signal power and nonlinear coefficient, and (2) subtractive correction of the segmented signal. This segmentation allows each part to be optimized independently, reducing the need for multiple full-stage BP units while maintaining compensation accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts and separately processes the additive interference component from the total nonlinear damage. By calculating the interference term based on signal power and nonlinear coefficient, and removing it through subtraction, the system addresses the dominant source of nonlinear distortion without requiring complete multi-stage back-propagation processing.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If multiple stages of digital Back-Propagation units are used to compensate nonlinear damage, then compensation completeness is improved, but system complexity increases

Engineering Contradiction:

Improvenonlinear damage compensation completenessVSAvoidnumber of BP unit stages

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the nonlinear damage compensation process into two distinct parts: (1) additive interference calculation based on signal power and nonlinear coefficient, and (2) subtractive correction of the segmented signal. This segmentation allows each part to be optimized independently, reducing the need for multiple full-stage BP units while maintaining compensation accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts and separately processes the additive interference component from the total nonlinear damage. By calculating the interference term based on signal power and nonlinear coefficient, and removing it through subtraction, the system addresses the dominant source of nonlinear distortion without requiring complete multi-stage back-propagation processing.

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of operation

If conventional nonlinear compensation methods are used, then implementation is straightforward, but accuracy is insufficient

Engineering Contradiction:

Improveimplementation simplicityVSAvoidnonlinear compensation accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent segments the nonlinear damage compensation process into two distinct parts: (1) additive interference calculation based on signal power and nonlinear coefficient, and (2) subtractive correction of the segmented signal. This segmentation allows each part to be optimized independently, reducing the need for multiple full-stage BP units while maintaining compensation accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts and separately processes the additive interference component from the total nonlinear damage. By calculating the interference term based on signal power and nonlinear coefficient, and removing it through subtraction, the system addresses the dominant source of nonlinear distortion without requiring complete multi-stage back-propagation processing.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentEP2495888B1Method and apparatus for compensating nonlinear damage

Publication Date: 2019.05.08 FUJITSU LTD

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AI summary

A Method and apparatus for compensating nonlinear damage are disclosed. The method for compensating nonlinear damage, comprising: determining an additive parameter indicating an amount of nonlinear damage based on a plurality of sampled signal sets among which a sampling time of an input signal varies according to different time; and subtracting the additive parameter from the input signal.