Single Fiber Full Duplex Aircraft Data Network

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Solution Overview

Problem

Current fiber optic networks in aircraft require two separate cables for bidirectional communication, leading to high component costs and complex installation, and existing bidirectional transceivers are not suitable for multimode fiber optic cables due to issues like mechanical susceptibility and power loss, limiting their deployment in harsh environments.

Innovation Solution

Implementing a full duplex, redundant optical network using multimode optical fibers and multi-frequency bidirectional transceivers that operate at different wavelengths, allowing for single-fiber communication and reducing the need for multiple cables and connectors, while utilizing COTS transceivers designed for single-mode fibers with multimode fiber optic cables.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two separate fiber optic cables are used for bidirectional communication, then communication reliability is improved, but component cost and installation complexity increase

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidinstallation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines transmit and receive functions into a single fiber optic cable by using wavelength division multiplexing. Two separate fiber cables are merged into one cable that carries both bidirectional communication channels simultaneously through different optical wavelengths, reducing installation complexity while maintaining communication reliability

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent adds the wavelength dimension to the single fiber cable to accommodate bidirectional communication. By utilizing different wavelengths (frequencies) of light within the same physical medium, the system achieves full-duplex communication without requiring separate spatial paths, thus solving the contradiction between reliability and complexity

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Quantity of substance

If COTS bidirectional transceivers designed for single-mode fiber are used with multimode fiber, then cost is reduced, but mechanical misalignment susceptibility increases

Engineering Contradiction:
Improvecomponent costVSAvoidmechanical alignment reliability
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the core parameter of the transceiver from single-mode optimized to multimode-compatible by selecting VCSEL or FP laser sources that are inherently suited for multimode fiber. This parameter change allows the use of cost-effective COTS transceivers while maintaining mechanical alignment reliability in the multimode fiber environment

Inventive Principle:
Principle #35Parameter changes

3Speed

If single-mode fiber optic cable is used for bidirectional communication, then bandwidth and speed are improved, but susceptibility to mechanical misalignment and contamination increases

Engineering Contradiction:
Improvedata transmission speedVSAvoidmechanical misalignment susceptibility
Core Design Contradiction:
SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent changes the fiber mode parameter from single-mode to multimode while compensating for speed limitations through wavelength division multiplexing and full-duplex operation. The multimode fiber's larger core diameter provides mechanical alignment tolerance, and the system achieves high effective bandwidth through parallel wavelength channels

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If multimode fiber optic cable is used, then mechanical alignment tolerance is improved, but bandwidth and transmission distance are limited

Engineering Contradiction:
Improvealignment toleranceVSAvoidbandwidth capacity
Core Design Contradiction:
Ease of operationVSQuantity of substance

Solution Approach 1:

The patent compensates for multimode fiber's bandwidth limitations by introducing the wavelength dimension. Through wavelength division multiplexing, multiple data channels operate in parallel at different wavelengths within the same fiber, effectively multiplying the bandwidth capacity while maintaining the mechanical alignment advantages of multimode fiber

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 solution provides cost savings, simplified installation, and improved reliability by enabling efficient use of existing transceivers with multimode fibers, reducing Bit Error Rate and maintaining system interoperability in aircraft environments, while ensuring redundancy and safety.

Implementation Method 1

Bidirectional transceivers are designed to transmit laser light at one wavelength and receiver laser light at a different wavelength than the transmit wavelength

Methodology Applied
Scientific EffectLaser: Laser

Implementation Method 2

employ a network architecture that allows for redundancy by creating multiple network backbones operating in parallel or parallel paths on a single network backbone

Methodology Applied
Scientific EffectWavelength division multiplexing:

Implementation Method 3

Fiber optics provide many technical advantages in terms of weight, volume, power, bandwidth

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP2002572B1Single fibre links for full duplex aircraft data network
Publication Date: 2016.03.09 THE BOEING CO
  • EP2002572B1 patent drawingFigure 1
  • EP2002572B1 patent drawingFigure 2
  • EP2002572B1 patent drawingFigure 3

AI summary

A method for creating a full duplex fiber optic network using one single fiber optic cable of the multimode fiber type for simultaneous transmission and reception is described. The method includes the steps of equipping end user devices and switches with bidirectional transceivers utilizing multi-frequency lasers, allocation of wavelengths to the end user devices to assure interoperability of redundant systems, and connecting the elements with multimode fiber optic cable. The network components include multi-frequency bidirectional transceivers, switches, and multimode fiber optic cable. This full duplex fiber optic network can be created as a single-backbone network or multiple-backbone network operating in series or in parallel to provide backup redundancy. Various embodiments are disclosed to show the versatility and scalability of the network.