Clock Fault Localization via Frequency Offset Comparison
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Solution Overview
Problem
In mobile communications, determining a faulty clock in a wireless base station is challenging due to the difficulty in distinguishing between a faulty local clock and a faulty received clock, especially when frequency offsets exceed the ±4.6 ppm threshold.
Innovation Solution
A network device method that compares frequency offsets between at least two clocks and a local clock to determine if the local clock or a received clock is faulty, using conditions such as the quantity of clocks with frequency offsets exceeding a threshold to identify clock faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency offset threshold comparison is used to detect clock faults, then clock fault detection capability is improved, but the ability to distinguish between local clock faults and received clock faults deteriorates
Solution Approach 1:
The patent segments the fault detection process into two distinct stages: first detecting whether a fault exists by comparing frequency offsets against a threshold, then identifying the fault source by comparing the local clock's frequency offset with received clocks' frequency offsets. This segmentation resolves the contradiction by separating detection capability from identification difficulty.
Solution Approach 2:
The patent introduces frequency offset comparison as an intermediary mechanism. Instead of directly identifying fault sources, the system first uses frequency offset threshold comparison to detect faults, then uses frequency offset differential comparison to identify whether the local or received clocks are faulty. This intermediary approach improves detection while maintaining identification accuracy.
2Measurement precision
If multiple frequency offset comparisons are performed to identify fault sources, then fault localization precision is improved, but system complexity increases
Solution Approach 1:
The patent implements a dynamic two-stage detection mechanism that adapts the comparison process based on initial detection results. The system first performs threshold-based detection, and only if a fault is detected does it proceed to the second stage of source identification through differential comparison. This dynamic approach improves precision while avoiding unnecessary complexity when no faults are present.
Solution Approach 2:
The patent performs preliminary frequency offset threshold comparison before conducting more complex source identification comparisons. By first determining whether a fault exists, the system prepares the groundwork for precise localization only when necessary, reducing overall system complexity while maintaining high precision when faults are detected.
Data Source
AI summary
A method for locating a clock fault includes that a network device locates a clock fault source based on whether first frequency offsets between a plurality of input clocks and a local clock exceed a frequency offset threshold, or based on whether second frequency offsets between the input clocks exceed a relative frequency offset threshold.