Frequency-Domain Signal Correction for Optical Channel Distortion

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Solution Overview

Problem

Current signal processing methods for optical receivers face inefficiencies due to high calculation efforts required to correct distortions introduced by channel imperfections such as chromatic dispersion and polarization-related issues, which affect the accuracy and efficiency of data transmission.

Innovation Solution

A signal processing apparatus that corrects distortions by performing two multiplication operations with derived correction functions and a summation operation in the frequency domain, using a transfer function of the signal processing path, allowing for efficient distortion correction with minimal computational effort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional signal processing methods are used to correct distortions from chromatic dispersion and polarization imperfections, then the accuracy of signal correction is improved, but the calculation effort and processing complexity increase significantly

Engineering Contradiction:
Improvesignal correction accuracyVSAvoidprocessing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent pre-calculates and stores correction functions for chromatic dispersion and polarization impairments before actual signal processing. These correction functions are determined in advance based on the optical channel characteristics, so that during real-time operation, the system only needs to apply the pre-computed correction functions rather than performing complex iterative calculations, thus reducing processing complexity while maintaining correction accuracy

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent separates the correction of different types of impairments (chromatic dispersion and polarization effects) into distinct correction functions that can be applied independently. This segmentation allows the system to address each type of distortion separately using optimized algorithms, reducing the overall computational burden compared to treating all impairments in a unified complex processing framework

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If conventional signal processing methods are used to correct distortions, then the signal processing accuracy is improved, but the processing time increases

Engineering Contradiction:
Improvesignal processing accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The correction functions are computed and stored in advance before the actual data transmission occurs. During real-time signal processing, the system applies these pre-computed correction functions through simple multiplication operations in the frequency domain, avoiding time-consuming iterative calculations and significantly reducing processing time while maintaining high correction accuracy

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If conventional signal processing methods are used to correct distortions, then the correction accuracy is improved, but the computational effort increases

Engineering Contradiction:
Improvecorrection accuracyVSAvoidcomputational effort
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The computationally intensive task of determining correction functions is performed in advance when computational resources are available. The resulting correction functions are then applied during real-time operation through efficient frequency domain multiplication, which requires minimal computational effort and energy, thus maintaining high correction accuracy while significantly reducing real-time computational requirements

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces complex time-domain signal processing operations with frequency domain operations. By transforming the signal to the frequency domain using FFT, applying correction functions through simple multiplication, and then transforming back, the system achieves the same correction accuracy with dramatically reduced computational complexity and energy consumption

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2502365B8Signal processing apparatus, transmitter, receiver and method
Publication Date: 2015.10.28 HUAWEI TECH CO LTD

AI summary

A signal processing apparatus (100, 300, 400) for correction of a distortion introduced by a signal processing path into a processed signal is provided The signal processing apparatus (100, 300, 400) comprises a transformer (110, 430a, 430b) for transforming the processed signal into a transformed signal in frequency domain, a processor (150, 350, 420) for determining a first correction function (C1) and a second correction function (C2) upon the basis of a transfer function of the signal processing path, a first multiplier (120, 433a, 433b) for multiplying values of the transformed signal with coefficients of the first correction function (C1) to obtain a first corrected signal, a signal reverser (130, 140, 437a, 437b, 439a, 439b) for reversing an order of values in a copy of the transformed signal to obtain a reversed transformed signal, a second multiplier (125, 435a, 435b) for multiplying values of the reversed transformed signal with coefficients of the second correction function (C2) to obtain a second corrected signal, and an adder (160, 440a, 440b) for adding the first corrected signal and the second corrected signal to obtain a corrected output signal