Frequency Synchronization Accuracy Estimation for Mobile Handover
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Solution Overview
Problem
Existing methods for estimating frequency synchronization accuracy between slave and master clocks in communication networks are inadequate, leading to inaccurate delay measurements and unreliable call handovers in mobile networks due to clock skews, which are not effectively compensated for in real-time.
Innovation Solution
A method that involves receiving timing messages with timestamps from a master clock, deriving a corrected clock using a digital phase-locked loop, estimating the average progression of the corrected clock, and calculating synchronization accuracy to ensure accurate frequency synchronization, which is used as a quality metric for call handover decisions in mobile networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If timing messages are received and a corrected clock is derived using a digital phase-locked loop, then frequency synchronization accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements a digital phase-locked loop that continuously receives timing messages from a master clock, compares the slave clock signal with the master clock signal, and adjusts the slave clock frequency in real-time based on the phase difference feedback. This closed-loop feedback mechanism enables automatic frequency synchronization without requiring complex manual calibration or intervention, resolving the contradiction by achieving high measurement precision through an automated feedback system rather than complex device architecture.
Solution Approach 2:
The slave clock device performs self-synchronization by automatically deriving the corrected clock from received timing messages using the digital phase-locked loop. The system autonomously estimates its own synchronization accuracy and adjusts its operation accordingly, eliminating the need for external synchronization equipment or complex coordination mechanisms, thus improving frequency synchronization accuracy while maintaining relatively simple device complexity.
2Measurement precision
If clock skew compensation is performed in real-time, then delay measurement accuracy is improved, but processing time increases
Solution Approach 1:
The digital phase-locked loop operates continuously to maintain frequency synchronization between the slave and master clocks. By ensuring continuous frequency alignment, the system eliminates the need for periodic skew compensation calculations and adjustments, allowing delay measurements to be taken at any time with high accuracy without incurring additional processing delays. The continuous synchronization action makes the compensation process transparent and time-efficient.
Solution Approach 2:
The system performs frequency synchronization preliminarily and continuously before delay measurements are taken. By maintaining the clocks in synchronous state through ongoing phase-locked loop operation, the measurement process itself does not require additional skew compensation steps, thus achieving high delay measurement accuracy without increasing processing time during the actual measurement.
3Reliability
If synchronization accuracy estimation is performed using the ratio of interval to average progression of the corrected clock, then reliability of handover decisions is improved, but calculation complexity increases
Solution Approach 1:
The patent transforms the complex problem of synchronization accuracy estimation into a simple parameter calculation. By deriving the corrected clock through the digital phase-locked loop and then calculating the ratio of the known interval between timing messages to the average progression of the corrected clock, the system obtains synchronization accuracy as a straightforward parameter. This parameter can be directly used to evaluate whether handover conditions are met, improving handover decision reliability while keeping the calculation method simple and computationally efficient.
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 enables real-time estimation and improvement of frequency synchronization accuracy, reducing the number of dropped calls by ensuring reliable handover processes and accurate network delay measurements.
Implementation Method 1
deriving, in the slave device, using said timing messages, a corrected clock which is an adjusted version of the first clock and which is synchronized to the second clock
Data Source
AI summary
This invention relates to the use of frequency synchronization accuracy as an additional quality metric for mobile call handover between base stations. Call handover is of major importance within any mobile network; without checking frequency synchronization before handover dropped calls and interrupted communication can result.