Extender Unit Gain Assembly for PON Fault Isolation
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Solution Overview
Problem
Extended passive optical networks (PONs) face challenges in maintaining network resilience due to longer fiber lengths, increased vulnerability to fiber breakage, and the need for efficient protection schemes that coordinate between distant OLTs, which can lead to false fault detection or failure to detect faults, especially when extending protection beyond collocated OLTs.
Innovation Solution
The implementation of extender units with gain assemblies that can be selectively enabled or disabled, along with a failover unit to detect faults and switch between enabled and disabled states, ensuring that only one OLT is active at a time, and a failover protocol to manage state transitions and fault detection, eliminating the need for complex coordination mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If extender units with gain assemblies are used to extend PON reach, then the network reach is improved, but the vulnerability to fiber breakage increases due to longer fiber lengths
Solution Approach 1:
The patent divides the extended PON into multiple segments by introducing intermediate extender units along the fiber path. Each extender unit serves as an independent protection domain, allowing fault isolation between segments. When a fiber breakage occurs in one segment, only that segment is affected, not the entire network, thus reducing overall vulnerability while maintaining extended reach.
2Area of stationary object
If protection schemes are extended beyond collocated OLTs to distant locations, then the network coverage is improved, but false fault detection occurs due to coordination complexity
Solution Approach 1:
The protection scheme is segmented into independent domains managed by local extender units. Each extender unit independently monitors its own segment for faults, eliminating the need for complex coordination between distant OLTs. This segmentation prevents false fault detection by isolating monitoring functions to local segments, while still enabling broad network coverage through the distributed architecture.
Solution Approach 2:
The extender unit acts as an intermediary between distant OLTs, providing local fault detection and protection management. Instead of requiring direct coordination between remote OLTs, the extender unit mediates by handling fault detection and switching locally, thus eliminating coordination complexity while maintaining extended network coverage.
3Reliability
If complex coordination mechanisms are used between distant OLTs for protection switching, then the protection coverage is improved, but the device complexity increases
Solution Approach 1:
The patent extracts the coordination function from the OLTs and relocates it to the extender units. Each extender unit independently manages protection switching for its segment, eliminating the need for complex inter-OLT coordination protocols. This extraction simplifies the overall system by removing centralized coordination complexity while maintaining comprehensive protection coverage through distributed local management.
Solution Approach 2:
Each extender unit performs self-service by independently detecting faults and executing protection switching within its own segment without requiring coordination with other OLTs. This self-service capability eliminates complex coordination mechanisms while maintaining full protection coverage, as each unit autonomously manages its protection domain.
4Reliability
If failover protocols are implemented to switch between working and protection extenders, then the network resilience is improved, but the time to restore service increases
Solution Approach 1:
The failover protocol is segmented to operate independently within each extender unit's domain. When a fault occurs, only the affected segment initiates failover, while other segments continue operating normally. This segmentation limits the scope of failover operations, reducing the overall time to restore service by preventing coordinated shutdowns across the entire network.
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 enhances the resilience of extended PONs by ensuring reliable fault detection and switching, reducing the risk of false alarms and improving fault sectionalization, while simplifying coordination and eliminating the need for dedicated communication links between distant OLTs.
Implementation Method 1
a first gain assembly, the first extender unit being operable selectively either in an enabled state, in which the first gain assembly amplifies a signal received at either port of the first extender unit and couples it to the other port of the first extender unit
Implementation Method 2
in a disabled state, in which the first gain assembly blocks coupling of a signal from either port of the first extender unit to the other port of the first extender unit
Data Source
AI summary
Extender apparatus for an optical network includes first and second extender units having an network-facing port for connection to a backhaul fiber and a subscriber-facing port for connection to a feeder fiber. Each extender unit includes a gain assembly and is operable selectively either in an enabled state, in which the gain assembly amplifies a signal received at either port of the extender unit and couples it to the other port of the extender unit, or in a disabled state, in which the gain assembly blocks coupling of a signal from either port of the extender unit to the other port of the extender unit. A failover unit is operable when the first extender unit is in the enabled state and the second extender unit is in the disabled state to detect occurrence of at least one fault condition in the first extender unit. The failover unit is responsive to the fault condition in the first extender unit to switch the first extender unit to the disabled state and the second extender unit to the enabled state.