Station-Side Device Wavelength Pairing for Chromatic Dispersion Delay

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In WDM/TDM-PON systems, chromatic dispersion delay caused by long-distance transmission leads to significant delays that exceed the allowable time in existing PON systems, particularly in Next Generation-PON2, affecting the system's performance and synchronization.

Innovation Solution

A station-side device configures wavelength pairs for upstream and downstream signals to minimize chromatic dispersion delay by allocating wavelengths in a manner that reduces the maximum chromatic dispersion delay amount, either by pairing upstream signals from the short wavelength side with downstream signals from the long wavelength side or vice versa, and dynamically adjusts wavelength pairs if the calculated delay exceeds a predetermined threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If wavelength pairs are allocated from the short wavelength side for both upstream and downstream signals, then the allocation is simple and systematic, but the chromatic dispersion delay amount becomes large and exceeds allowable time in long-distance transmission

Engineering Contradiction:

Improvewavelength allocation simplicityVSAvoidchromatic dispersion delay

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent inverts the conventional wavelength allocation approach by pairing upstream signals from the short wavelength side with downstream signals from the long wavelength side (or vice versa), rather than pairing both from the short wavelength side. This inversion strategy balances the chromatic dispersion delay amounts between upstream and downstream signals, reducing the maximum delay to within allowable time while maintaining systematic allocation.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If wavelength pairs are allocated to minimize chromatic dispersion delay, then transmission performance improves, but the allocation complexity increases due to dynamic adjustment requirements

Engineering Contradiction:

Improvetransmission performanceVSAvoidwavelength allocation control

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements dynamic wavelength pair allocation where the station-side device calculates chromatic dispersion delay amounts based on actual transmission conditions and adjusts wavelength assignments accordingly. This dynamic approach ensures optimal transmission performance by adapting to varying network conditions while managing the complexity through automated control algorithms.

Inventive Principle:

Principle #15Dynamics

3Length of moving object

If long-distance transmission is supported, then network coverage expands, but chromatic dispersion delay exceeds allowable time limits

Engineering Contradiction:

Improvetransmission distanceVSAvoidchromatic dispersion delay

Core Design Contradiction:

Length of moving objectVSLoss of time

Solution Approach 1:

The patent changes the wavelength selection parameters dynamically based on transmission distance and chromatic dispersion characteristics. By adjusting which wavelength pairs are allocated to upstream and downstream signals according to the specific transmission conditions, the system maintains acceptable delay levels even over long distances, thereby expanding network coverage without compromising timing performance.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach reduces the chromatic dispersion delay in WDM/TDM-PON systems, ensuring that the delay remains within acceptable limits even at longer transmission distances, thereby improving the system's performance and synchronization capabilities.

Implementation Method 1

a wavelength division multiplexing optical communication system which performs single-core bidirectional transmission of a plurality of upstream and downstream signals

Methodology Applied

Scientific EffectWavelength division multiplexing: Dispersion (of waves)

Implementation Method 2

chromatic dispersion delay caused by long-distance transmission leads to significant delays that exceed the allowable time in existing PON systems

Methodology Applied

Scientific EffectChromatic dispersion: Dispersion (of waves)

Data Source

PatentUS10361807B2Station-side device and wavelength control method

Publication Date: 2019.07.23 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

An OLT configures combinations of wavelength pairs used for upstream and downstream signals, in a wavelength multiplexing optical communication system which performs single-core bidirectional transmission of a plurality of upstream and downstream signals, in such a way that the maximum value of the chromatic dispersion delay amount calculated from each wavelength pair is less than the maximum value of the chromatic dispersion delay amounts calculated when the combinations of wavelength pairs used for upstream and downstream signals are both allocated from the short wave side.