TWDM PON Variable Splitting Ratio Optical Bypass

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Solution Overview

Problem

Passive Optical Networks (PONs) face limitations in resource allocation flexibility and data rate due to power losses induced by non-powered optical splitters, particularly in high-capacity applications like wireless backhauling, where increased bandwidth is required sporadically.

Innovation Solution

An optical device that manages optical resources by using a multi-stage splitter and optical coupler configuration to bypass the second portion of WDM signals from cascaded splitters, preventing loss and allowing for increased data rates, and an optical switch to reconfigure signal routing based on demand.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a 1 by 64 optical splitter is used to connect one OLT to multiple ONUs, then the network coverage and number of connected users are improved, but the signal loss increases to around 21 dB

Engineering Contradiction:
Improvenumber of connected ONUsVSAvoidsignal loss
Core Design Contradiction:
Quantity of substanceVSLoss of energy

Solution Approach 1:

The optical network is segmented into multiple stages of splitters (first stage 1:4 splitter, second stage 1:16 splitter) instead of using a single 1:64 splitter. This segmentation reduces the signal loss at each stage while achieving the same overall connectivity, allowing selective bypass of certain signal portions to maintain higher power levels for specific applications.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system introduces dynamic reconfigurability through optical switches that can selectively bypass the second stage splitter for specific wavelength channels or time slots. This allows the network to adaptively adjust the splitting ratio and signal path based on real-time bandwidth requirements, providing higher power levels when needed while maintaining overall network flexibility.

Inventive Principle:
Principle #15Dynamics

2Productivity

If higher bandwidth is allocated to specific users during busy hours or special events, then the data rate for those users is improved, but the power budget is exceeded due to accumulated splitter losses

Engineering Contradiction:
Improvedata rateVSAvoidpower budget
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The system enables dynamic reconfiguration of the optical network topology using controllable optical switches. During busy hours or special events, the switches can bypass the second stage splitter for specific wavelength channels allocated to high-bandwidth users, thereby reducing signal loss and maintaining sufficient power budget to support higher data rates without exceeding system limits.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

Different signal paths are provided with different quality characteristics - full splitting for standard users and bypass configuration for premium users requiring higher bandwidth. This local differentiation allows specific users to receive enhanced signal quality and higher power levels while other users continue to use the standard splitting path, optimizing overall network resource allocation.

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If wavelengths are allocated to end-users in WDM-PON, then resource allocation is simplified, but flexibility is reduced when end-user requirements change

Engineering Contradiction:
Improveresource allocation simplicityVSAvoidflexibility
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The system combines static WDM wavelength allocation with dynamic optical switching capabilities. The underlying wavelength assignment remains simple and structured, while the optical switches enable real-time reconfiguration of signal paths, splitting ratios, and bandwidth allocation. This allows the network to maintain the simplicity of WDM architecture while adding the flexibility to adapt to changing user requirements through dynamic path rerouting and resource reallocation.

Inventive Principle:
Principle #15Dynamics

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 configuration enhances data rates by avoiding losses from cascaded splitters, enabling higher bandwidth allocation to specific users while maintaining similar bandwidth requirements for optical components, and supports higher order modulation formats.

Implementation Method 1

said first portion being processed by a first optical splitter and a second optical splitter

Methodology Applied
Scientific EffectOptical splitting:

Implementation Method 2

said processed first portion being then combined with said second portion

Methodology Applied
Scientific EffectOptical coupling:

Data Source

PatentEP3588808B1TWDM PON with variable splitting ratio
Publication Date: 2022.02.23 NOKIA SOLUTIONS & NETWORKS OY
  • EP3588808B1 patent drawingFigure 1~2
  • EP3588808B1 patent drawingFigure 3
  • EP3588808B1 patent drawingFigure 4a~4b

AI summary

An optical device for managing optical resources from Wavelength Division Multiplexing "WDM" optical signals in a Passive Optical Network "PON", the optical device being adapted to process an optical signal into a plurality of output optical signals, the optical device comprising: - a wavelength demultiplexer (2), - a multi-stage optical splitter connected to the wavelength demultiplexer and comprising a first optical splitter (3) cascaded with a second optical splitter (4), - a coupler (5) connected to the second optical splitter, - an optical bypass (31) connecting the wavelength demultiplexer (2) and the coupler (5), the wavelength demultiplexer (2) being configured: - to select a first portion of the optical signal and, - to select a second portion of said optical signal and, - to provide said second portion to the coupler (5) through the optical bypass (31), the coupler (5) being configured to combine said second portion with the first portion after being processed by the first optical splitter (3) and the second optical splitter (4).