GPON Overlay on Legacy Optical Access Network
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Solution Overview
Problem
Legacy optical access networks, such as fiber-in-the-loop (FITL) systems, have limited bandwidth capabilities, restricting the services that can be provided to subscribers, and existing infrastructure is underutilized for higher bandwidth services.
Innovation Solution
A gigabit passive optical network (GPON) is overlaid on the legacy FITL network, using a shared fiber and WDM filters to multiplex and demultiplex signals, allowing both GPON and FITL communications to operate on the same fiber link with sufficient isolation and low loss, enabling higher bandwidth services while maintaining existing service delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a legacy optical access network is used, then existing infrastructure can be maintained, but bandwidth capability is limited
Solution Approach 1:
The patent combines GPON and legacy FITL networks into a single shared fiber infrastructure. WDM filters multiplex GPON downstream (1550nm) and upstream (1610nm) signals with legacy FITL signals on the same fiber, enabling both high-bandwidth GPON services and existing legacy services to coexist, thereby merging the capabilities of both systems to achieve enhanced productivity while utilizing existing infrastructure.
2Productivity
If GPON is overlaid on legacy network, then higher bandwidth services are enabled, but signal interference may occur
Solution Approach 1:
The patent introduces WDM (wavelength division multiplexing) filters as intermediary devices between the GPON and legacy FITL networks. These filters separate signals based on wavelength, allowing GPON downstream (1550nm) and upstream (1610nm) signals to pass through while blocking legacy FITL signals, and vice versa. This intermediary mechanism enables high bandwidth services while preventing signal interference between the two networks.
3Reliability
If separate fibers are used for GPON and legacy network, then signal isolation is achieved, but infrastructure complexity increases
Solution Approach 1:
The patent merges GPON and legacy FITL networks onto a single shared fiber infrastructure using WDM filters. Instead of deploying separate fibers for each network, the system combines both networks on one fiber, reducing infrastructure complexity while maintaining signal isolation through wavelength-based separation. This approach eliminates the need for additional fiber deployments and reduces overall system complexity.
4Reliability
If WDM filters are added to multiplex signals, then signal isolation is improved, but insertion loss increases
Solution Approach 1:
The patent optimizes the operational parameters of the WDM filters to achieve the desired balance between signal isolation and insertion loss. The filters are designed with specific wavelength passbands and stopbands that provide sufficient isolation between GPON and legacy signals while minimizing attenuation of the transmitted signals. By carefully selecting and tuning the filter parameters, the system achieves effective signal separation with acceptable energy loss.
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 the deployment of higher bandwidth services over existing fiber infrastructure, enhancing service capabilities without excessive power loss or interference, thereby maximizing the use of existing network resources.
Implementation Method 1
a WDM filter providing an isolation of at least 27 dB and a loss less than 0.75 dB including connector loss
Data Source
AI summary
Methods, systems, and apparatus for overlaying a passive optical network on a legacy optical access network are disclosed. In one aspect a system includes a legacy optical access network in a copper loop plant. The legacy optical access network provides access to customer premises. The system also includes a gigabit passive optical network (GPON) that is overlaid on the legacy optical access network. A fiber is shared by the GPON and the legacy optical access network. The GPON can provide a plurality of channels on the shared fiber at wavelengths that are separate and independent of wavelengths of the legacy optical access network.