Coherent Optical Restoration Using SDFEC Fault Triggers
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Solution Overview
Problem
Current optical layer restoration mechanisms in coherent optical networks are slow and unreliable due to limitations in optical power monitoring devices and network latencies, leading to delayed and incomplete fault detection and propagation, which hinders fast and cost-effective restoration in cases of network failures.
Innovation Solution
The method involves converting optical signals into digital signals for fault monitoring at both the optical and digital layers using soft decision forward error correction algorithms, enabling quick detection of errors in the data stream and triggering restoration paths through a local restoration engine and signaling engine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical power monitoring devices (OPM) are used to detect faults in the optical layer, then fault detection can be performed, but the restoration mechanism is delayed due to OPM limitations and network latencies
Solution Approach 1:
The patent introduces an intermediary mechanism by converting optical signals to digital signals and using digital layer FEC defects as a mediator to trigger optical layer restoration. This intermediary approach allows the system to detect faults through the digital layer where FEC can identify errors more rapidly, thereby triggering restoration without waiting for the slow OPM-based optical layer fault detection, thus resolving the contradiction between reliable fault detection and fast restoration.
Solution Approach 2:
The patent replaces the mechanical/optical monitoring system (OPM) with a digital signal processing system. By substituting the optical power monitoring mechanism with digital signal analysis and FEC-based error detection, the system achieves faster fault detection capability while maintaining reliability, directly addressing the time delay issue inherent in OPM-based systems.
2Speed
If optical loss of signal (OLOS) triggers are used for fast restoration, then restoration speed can be improved, but the triggers cannot be reliably used in case of sliceable light sources where multiple super-channels originate
Solution Approach 1:
The patent applies segmentation by monitoring individual super-channel levels rather than relying on aggregate OLOS triggers. By segmenting the monitoring granularity to the super-channel level, the system can detect faults in specific channels even when multiple super-channels share a common light source, making the trigger mechanism reliable for sliceable light sources while maintaining fast restoration capability.
Solution Approach 2:
The patent implements local quality monitoring by detecting faults at the specific super-channel level rather than using global OLOS triggers. This localized approach allows the system to identify and respond to failures in individual super-channels or slices, ensuring that restoration triggers are reliably generated even when multiple super-channels share common infrastructure, thus resolving the reliability issue while preserving speed.
3Measurement precision
If OPM measurements are used to monitor optical channel health, then power levels can be monitored, but the measurements take a large amount of time (order of seconds) and cannot conclusively determine if digital traffic is down
Solution Approach 1:
The patent replaces the slow mechanical OPM measurement system with a digital signal processing system that analyzes digital signals and FEC correction data. This substitution eliminates the time-consuming optical power measurements while providing more conclusive information about actual digital traffic health, as FEC defects directly indicate whether digital traffic is affected, resolving both the time and precision contradictions.
Solution Approach 2:
The patent introduces digital signal analysis and FEC defect detection as an intermediary between optical power monitoring and restoration triggering. This intermediary layer provides conclusive information about digital traffic status without requiring slow OPM measurements, as the digital layer can immediately detect whether traffic is degraded or down through FEC error analysis, thus resolving the contradiction between measurement precision and measurement time.
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 approach allows for faster and more reliable optical channel restoration by quickly detecting failures and establishing alternative paths, reducing traffic outages and operational costs compared to existing methods.
Implementation Method 1
a first node converts, by circuitry, an optical layer in a working path between the first node and a second node, to a data stream in a digital layer
Data Source
AI summary
Methods, nodes and control modules are disclosed. In the method, circuitry of a first node in a mesh network converts an optical layer in a working path between the first node and a second node, to a data stream in a digital layer. The working path carries data traffic from the first node to the second node in the optical layer of the mesh network when there is no failure in the working path. Circuitry of the first node in the mesh network detects a failure in the working path due to detection of an error in the data stream in the digital layer. The circuitry of the first node establishes, through transmission of at least one signal from the first node to the second node, a restoration path in the optical layer based on, at least in part, detection of the error in the data stream in the digital layer.