Distributed Optical Combining for OBI-Free Passive FTTH Networks
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Solution Overview
Problem
Existing RFoG communication systems face challenges with Optical Beat Interference (OBI) that limit upstream and downstream traffic, requiring additional power for mitigation solutions like wavelength adjustments and optical amplifiers, which increase power consumption and are not suitable for passive FTTH deployments.
Innovation Solution
The implementation of an active combiner system that uses remote optical pumping to eliminate OBI, allowing active combiners to behave passively by providing power optically, reducing the need for multiple power locations and enhancing power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional OBI mitigation solutions (wavelength adjustments, optical amplifiers) are implemented, then OBI is reduced or eliminated, but power consumption increases
Solution Approach 1:
The patent replaces active electronic OBI mitigation components (photodiodes, lasers, optical amplifiers) with a passive optical combining approach. Multiple upstream optical inputs are combined directly through optical couplers without photodetection and retransmission, eliminating the need for power-consuming electronic components while maintaining OBI-free operation.
Solution Approach 2:
The optical combining system uses the optical signals themselves to carry information through passive optical components. The system serves itself by utilizing the inherent properties of optical waves (superposition principle) to combine signals without requiring external power sources, making the combining process self-sufficient and power-free.
2Object-affected harmful factors
If distributed combining with multiple combiners is used, then OBI is eliminated, but the number of power locations increases exponentially
Solution Approach 1:
The patent divides the upstream combining function into multiple passive optical combiners distributed along the fiber network. Each combiner handles a subset of upstream inputs locally, eliminating the need for a single centralized active combining point. This segmentation allows OBI-free combining while distributing complexity without exponential power location growth.
Solution Approach 2:
The patent transitions from a single-dimension centralized combining architecture to a multi-dimensional distributed architecture. By placing passive combiners at multiple locations along the fiber path (spatial dimension), the system achieves OBI-free combining without requiring proportional increases in power locations, effectively adding a spatial distribution dimension to the combining topology.
3Use of energy by moving object
If passive FTTH deployment is pursued, then power requirements are minimized, but OBI mitigation capability is reduced
Solution Approach 1:
The patent extracts the active electronic components (photodiodes, lasers, amplifiers) that cause power consumption and OBI from the upstream combining process. By removing these components and replacing them with passive optical combining, the system maintains OBI mitigation capability while achieving the power minimization goals of passive FTTH deployment.
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 enables distributed OBI-free combining without the exponential increase in power requirements, supporting longer fiber lengths and more splits, while maintaining high upstream and downstream capacity, and reducing system costs and complexity.
Implementation Method 1
The implementation of an active combiner system that uses remote optical pumping to eliminate OBI, allowing active combiners to behave passively by providing power optically
Data Source
AI summary
Implementing a laser into a system that uses a remote powered combiner or an aggregating combiner (AC) with one or more in-range contributing combiners may provide power to the downstream contributing combiners (CC). The power may be provided on the same fiber that downstream signals and the upstream signals traverse.