LOF Alarm Pre-Detection Using Maintenance Signal Frame Alignment

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Solution Overview

Problem

Existing methods fail to address the issue of resource wastage due to erroneous detection of LOF alarms in optical transport networks, leading to unnecessary switching and processing.

Innovation Solution

Implementing a mechanism to detect LOF pre-alarms and insert maintenance signal frames for frame alignment, preventing erroneous detection of LOF alarms and reducing resource wastage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the second network device inserts a first maintenance signal frame at an ingress end to maintain frame alignment, then frame alignment is ensured and LOF pre-alarm detection is enabled, but device complexity increases due to additional signal insertion and detection mechanisms

Engineering Contradiction:
Improveframe alignment reliabilityVSAvoidsignal processing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by detecting frame alignment failures before they reach the LOF alarm threshold (first duration < second duration) and inserting maintenance signal frames proactively. This early intervention prevents complete frame loss and ensures continuous frame alignment, resolving the contradiction by maintaining reliability through advance action while managing complexity through targeted rather than continuous signal insertion.

Inventive Principle:
Principle #10Preliminary action

2Speed

If the detection duration for LOF alarm is reduced to enable faster detection, then response speed improves, but measurement precision deteriorates due to insufficient sampling period

Engineering Contradiction:
Improvealarm detection speedVSAvoidframe alignment failure detection precision
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The patent segments the alarm detection process into two distinct stages: LOF pre-alarm detection with a shorter first duration for early warning, and LOF alarm detection with a longer second duration for confirmation. This segmentation allows the system to achieve both fast response (through pre-alarm) and high precision (through confirmed alarm), resolving the contradiction by dividing the detection function into complementary parts.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4152694B1Alarm processing method and apparatus
Publication Date: 2026.03.25 HUAWEI TECH CO LTD
  • EP4152694B1 patent drawingFigure 1~2
  • EP4152694B1 patent drawingFigure 3~4
  • EP4152694B1 patent drawingFigure 5

AI summary

This application provides an alarm processing method and apparatus, to resolve a problem that resources are wasted due to erroneous detection of an LOF alarm. Specifically, a mechanism of configuring and detecting an LOF pre-alarm is provided. A detection condition of the LOF pre-alarm is that it is detected that a frame alignment failure lasts for first duration. A detection condition of the LOF alarm is that it is detected that a frame alignment failure lasts for second duration. The second duration is less than the first duration. When detecting the LOF pre-alarm, a network device inserts a first maintenance signal frame. The first maintenance signal frame supports frame alignment. In other words, a network device that receives the first maintenance signal frame may perform normal frame alignment, so that no alarm is reported, for example, the LOF alarm is not triggered. Therefore, the network device that receives the first maintenance signal frame does not erroneously generate the LOF alarm because a frame alignment failure lasts for the second duration, and therefore does not report the LOF alarm or perform mis-switching, and resource waste is avoided.