Wavelength-Independent PON Extender for Long-Reach Split Networks
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Solution Overview
Problem
Current passive optical networks (PONs) are limited by insertion loss and reach only up to 20 km due to high loss in passive splitters and the use of inexpensive customer equipment that limits optical performance, necessitating remote OLTs with increased costs and maintenance needs.
Innovation Solution
A PON extender system using a combination of Raman amplifiers and optical amplifiers (EDFAs/SOAs) with dispersion compensation modules (DCMs) to amplify and manage chromatic dispersion, enabling longer reach without remote OLTs, reducing costs and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If passive splitters are used to extend PON reach, then the network can serve more customers, but insertion loss increases and limits the distance to 20 km
Solution Approach 1:
The patent introduces remote OLT units as intermediary devices that actively amplify optical signals using Raman amplification and optical amplification. These intermediaries are placed at strategic points in the network to boost signal strength and compensate for splitter insertion losses, enabling the network to extend beyond the 20 km limitation while maintaining the ability to serve multiple customers through passive splitters.
2Length of stationary object
If remote OLTs are deployed to extend PON reach beyond 20 km, then network reach is improved, but system cost and maintenance complexity increase
Solution Approach 1:
The patent segments the PON architecture by introducing intermediate remote OLT units that divide the network into multiple sections. Each segment uses passive splitters for customer distribution, while the active amplification functions are concentrated in the segmented remote OLT units. This segmentation allows the network to extend reach without requiring a fully active architecture throughout, balancing performance improvement with manageable complexity.
3Ease of manufacture
If inexpensive customer equipment with directly modulated lasers is used, then cost is reduced, but optical performance is limited
Solution Approach 1:
The patent uses remote OLT units with advanced optical amplification (Raman and optical amplifiers) as intermediaries to compensate for the limited output power of inexpensive directly modulated lasers. The amplification infrastructure acts as a mediator that enhances the optical signals from cost-effective customer equipment, allowing the system to achieve extended reach and improved performance without requiring expensive customer premises equipment.
Data Source
AI summary
Systems and methods for operating a passive optical network (PON) extender. The methods comprise: receiving, by the PON extender, a first optical signal from a remote node device of a passive optical network via a first optical link; amplifying the first optical signal using a Raman amplifier of the PON extender to obtain a first Raman amplified optical signal; amplifying the first Raman amplified optical signal using a first optical amplifier of the PON extender to obtain an amplified uplink signal (wherein the first optical amplifier is different than the Raman amplifier); and passing the amplified uplink signal to an optical line terminal via a second optical link (wherein the optical line terminal is disposed locally at a hub site along with the PON extender).