Bidirectional Wavelength Access via Single-Fiber WDM Routing

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Solution Overview

Problem

The challenge in designing a device to improve node access performance in 5G mobile WDM networks is to enhance transmission efficiency while reducing the number of optical fibers required, particularly in low-cost wavelength division multiplexing networks.

Innovation Solution

A bidirectional wavelength access system comprising a first optical circulator and a wavelength division filter group that guides incident and returning light rays with specific wavelengths through a single-core optical fiber, allowing for bidirectional communication without the need for multiple fibers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional bidirectional communication using separate fibers for upstream and downstream is used, then communication reliability is improved, but the number of optical fibers required increases

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidnumber of optical fibers

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies wavelength division multiplexing to convert the traditional spatial separation (separate fibers for upstream and downstream) into a spectral dimension (different wavelengths for upstream and downstream). By using a single optical fiber and separating signals based on wavelength rather than physical direction, the system achieves bidirectional communication with half the fiber count while maintaining communication reliability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If multiple optical fibers are deployed for bidirectional communication, then communication performance is improved, but deployment cost and time increase

Engineering Contradiction:

Improvecommunication performanceVSAvoiddeployment time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent merges the upstream and downstream communication channels into a single optical fiber by using wavelength division multiplexing. Instead of deploying separate fibers for bidirectional communication, the system combines both directions into one fiber infrastructure, significantly reducing deployment time and cost while maintaining communication performance through spectral separation.

Inventive Principle:

Principle #5Merging (Combining)

3Quantity of substance

If wavelength division multiplexing is implemented, then the number of optical fibers is reduced, but device complexity increases

Engineering Contradiction:

Improvenumber of optical fibersVSAvoiddevice complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent introduces wavelength division multiplexers and demultiplexers as intermediary devices that enable wavelength-based signal separation and combination. These mediators facilitate the conversion between spatial and spectral domains, allowing the system to manage multiple communication directions through a single fiber while providing a structured approach to handling the increased device complexity through standardized multiplexing components.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 system reduces the number of optical fibers needed by half, lowering deployment costs and time, while maintaining efficient communication and allowing for easy installation and maintenance.

Implementation Method 1

The first optical circulator includes a first port, a second port, and a third port. The first wavelength division filter group guides a first incident light ray transmitted in the first main axis optical cable to the first port of the first optical circulator and guides a first returning light ray received from the third port of the first optical circulator into the first main axis optical cable.

Methodology Applied

Scientific EffectOptical circulation:

Implementation Method 2

The first wavelength division filter group is connected to a first main axis optical cable. The first wavelength division filter group guides a first incident light ray transmitted in the first main axis optical cable to the first port of the first optical circulator

Methodology Applied

Scientific EffectWavelength division filtering: Filter (optical)

Data Source

PatentUS20260074817A1Bidirectional wavelength access system

Publication Date: 2026.03.12 CHUNGHWA TELECOM CO LTD

AI summary

A bidirectional wavelength access system includes a bidirectional wavelength access device. The bidirectional wavelength access device includes an optical circulator and a wavelength division filter group. The optical circulator includes a first port, a second port, and a third port. The wavelength division filter group is connected to a main axis optical cable. The wavelength division filter group guides an incident light ray transmitted in the main axis optical cable to the first port of the optical circulator and guides a returning light ray received from the third port of the optical circulator into the main axis optical cable. The incident light ray and the returning light ray both have a first wavelength.