Optical Line Termination Node Redundancy via Circulators
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Solution Overview
Problem
Existing optical line termination nodes in passive optical networks (PONs) with duplicated feeder fibers are expensive and have a single point of failure, leading to connectivity issues when the feeder fiber breaks.
Innovation Solution
An optical line termination node with separate connection arrangements for working and protection fibers, using protection switching means and coupling means to provide distinct signal paths, eliminating the need for costly changeover switches and reducing the risk of single-point failures by using circulators and optical on-off switches for data communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a known OLT that supports duplicated feeder fibre is used, then the availability of the PON is increased, but the cost increases and a single point of failure remains
Solution Approach 1:
The patent segments the signal path into separate working and protection paths by using individual coupling means (circulators) for each fiber. This segmentation allows independent operation of each path, eliminating the single point of failure in the switching mechanism while maintaining duplicated feeder fiber capability.
Solution Approach 2:
The patent extracts the changeover switch from the system and replaces it with separate, dedicated coupling means for each fiber path. This removal of the switching mechanism eliminates the single point of failure while maintaining the ability to use either working or protection fiber independently.
2Reliability
If changeover switches are used for switching between working and protection fibers, then fiber failure protection is achieved, but cost increases and single point of failure is introduced
Solution Approach 1:
The patent removes the changeover switch from the system entirely and replaces it with separate coupling means (circulators) for each fiber path. This extraction eliminates the single point of failure associated with the switching mechanism while maintaining failure protection through the redundant fiber paths.
Solution Approach 2:
The patent introduces circulators as intermediary devices that enable bidirectional communication on each fiber path without requiring switching. These circulators act as mediators that allow the system to protect against fiber failures while avoiding the cost and reliability issues of changeover switches.
3Reliability
If separate signal paths are provided for working and protection states, then availability is increased, but device complexity increases
Solution Approach 1:
The patent makes each circulator multi-functional by enabling it to handle both working and protection fiber paths independently. Each circulator can operate in either path, providing universality that reduces the need for additional dedicated components for each path, thereby limiting the increase in device complexity.
Solution Approach 2:
The system provides self-service through the passive optical network architecture where the redundant fiber paths and circulators automatically provide protection without requiring active switching control. The separation of signal paths enables automatic failover while keeping the control mechanism simple.
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
The solution increases the availability of the optical line termination node by providing redundant signal paths, eliminating common failure points and reducing signal attenuation, while maintaining cost-effectiveness and compatibility with both tuneable and reflective transmitters.
Implementation Method 1
first coupling means being arranged for forwarding seeding light to the transceiver arrangement via the first primary link and second coupling means being arranged for forwarding the seeding light to the transceiver arrangement via the second primary link
Data Source
AI summary
An optical line termination node has a first connection arrangement for connecting a working fiber, a second connection arrangement for connecting a protection fiber, a transceiver arrangement having first primary link and a first secondary link, and protection switching means configured for being switched either in a working operating state or in a protection operating state.