Optical Network Element Loss of Frame Alarm Detection
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Solution Overview
Problem
In optical transmission networks, existing methods fail to detect frame failures and raise alarms promptly when a framer toggles between in-frame and out-of-frame states, leading to undetected degraded data reception, as the persistence filters may not raise alarms if the out-of-frame state persists for durations shorter than their time windows.
Innovation Solution
The method involves instantaneous detection and raising of a loss of frame alarm upon identifying a defect correlation, eliminating the need for time filtering of the defect correlation, thereby ensuring operators are alerted to degraded data reception even during frequent toggling between in-frame and out-of-frame states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If persistency filters with time windows are used to detect OOF state and defect correlation, then false alarms are reduced, but frame failures during frequent toggling between in-frame and out-of-frame states are not detected
Solution Approach 1:
The patent segments the alarm detection process into two distinct pathways: one for stable OOF states (using persistency filters) and one for toggling states (using instantaneous defect correlation detection). This segmentation allows each pathway to be optimized for its specific detection scenario, resolving the contradiction between reducing false alarms and detecting all frame failures.
Solution Approach 2:
The patent introduces dynamic switching between different detection modes based on the observed framer state. When toggling is detected, the system dynamically transitions to instantaneous defect correlation detection, while maintaining the persistency filter for stable states. This dynamic adaptation resolves the contradiction by adjusting the detection strategy according to the actual system conditions.
2Stability of the object's composition
If persistency filter with 2.5 sec time window is applied to defect correlation, then alarm stability is improved, but response time to frame failures is delayed or lost
Solution Approach 1:
The patent performs preliminary detection of defect correlation immediately when OOF state occurs, before applying the persistency filter. This preliminary action ensures that frame failures are detected without delay, while the persistency filter subsequently validates the alarm to ensure stability. The preliminary detection resolves the time loss issue while the filter maintains alarm stability.
Solution Approach 2:
The patent introduces an intermediary mechanism that bridges the instantaneous defect correlation detection and the persistency-filtered alarm generation. This intermediary evaluates the defect correlation in real-time and triggers alarms immediately when frame failures are detected, while the persistency filter operates in parallel to validate sustained conditions. This intermediary structure resolves both the response time and stability requirements simultaneously.
3Reliability
If time filtering is used for defect correlation, then noise is reduced, but detection of degraded data reception during toggling is lost
Solution Approach 1:
The patent implements feedback by continuously monitoring the framer state and adjusting the detection strategy accordingly. When toggling between in-frame and out-of-frame states is detected, the system provides feedback to switch to instantaneous defect correlation detection, ensuring that degraded transmission information is captured. This feedback mechanism resolves the contradiction by adapting the detection sensitivity to the actual transmission conditions.
Solution Approach 2:
The patent changes the detection parameter from filtered defect correlation to instantaneous defect correlation when toggling is detected. This parameter change allows the system to capture degraded transmission information during dynamic states while maintaining alarm validity through the persistency filter for stable states. The conditional parameter adjustment resolves both the information loss and reliability requirements.
Data Source
Figure 1a~1b
Figure 1c~2
AI summary
Proposed is a method of raising a loss of frame alarm in an optical transmission network at an optical network element. The method comprises the steps of detecting an out-of-frame (OOF) state, detecting a presence of the OOF state, by filtering the OOF state in time using at least one time window, detecting a loss of frame defect , in case the presence of the OOF state is detected, determining a defect correlation, by correlating the loss of frame defect with one or more further defects, and finally, in case of a presence of the defect correlation, instantaneously detecting a frame failure and raising a loss of frame alarm.