Access Device Time Synchronization via Iterative Drift Correction
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Solution Overview
Problem
In wireless mesh access control systems, there is a need for accurate time synchronization among access devices to ensure proper user access tracking and attendance generation, as time drift can lead to incorrect access records and system reliability issues.
Innovation Solution
A system and method where control circuitry generates health messages from access devices to read and compare initial device times, applying auto drift correction parameters to generate intermediate and final device times, ensuring synchronization with a predefined threshold, and utilizing network mapping to optimize communication routes for minimal delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wireless mesh technology is used to replace traditional electrical connections, then system security and cost-effectiveness are improved, but time synchronization accuracy deteriorates due to time drift in battery-powered access devices
Solution Approach 1:
The system implements a feedback mechanism where access devices periodically report their local time to the central controller, which compares it with controller time and calculates drift values. The controller then sends correction parameters back to the access devices to adjust their local clocks, forming a closed-loop feedback system that continuously maintains time synchronization accuracy despite the wireless battery-powered architecture.
Solution Approach 2:
The access devices perform self-correction of their local time by applying drift correction parameters received from the central controller. Instead of requiring manual intervention or continuous controller oversight, each device autonomously adjusts its own clock based on the calculated drift, enabling self-service time synchronization that maintains accuracy in the distributed wireless system.
2Reliability
If distributed architecture with battery-powered access devices is implemented, then system reliability is improved, but time drift occurs leading to incorrect access records
Solution Approach 1:
The system uses feedback to continuously monitor and correct time drift in distributed access devices. By periodically comparing local device time with central controller time and sending correction parameters back to devices, the system prevents time drift from accumulating to levels that would cause incorrect access records, thereby protecting data integrity while maintaining distributed architecture reliability.
3Measurement precision
If multiple time correction iterations are applied, then time synchronization accuracy is improved, but communication overhead and processing time increase
Solution Approach 1:
The system applies time correction in iterative stages rather than attempting perfect synchronization in a single step. First, a coarse correction is applied to bring the device time close to controller time, then a finer correction is applied to eliminate remaining drift. This partial action approach achieves high accuracy while avoiding the excessive processing time that would result from continuous fine-tuning corrections.
Data Source
AI summary
Disclose is a system (100), the system (100) including: the access devices (102) configured to communicate within; wherein a first access device (102a) of the access devices (102) is configured to generate a health message (154) and a control circuitry (104) that is coupled to the access devices (102), and configured to read an initial device time from the health message (154), thereafter compare the initial device time with a controller time, thereafter determine first auto drift correction parameters based on a result of the comparison, wherein a first time correction is applied to the initial device time to generate an intermediate device time; and compare the intermediate device time with the controller time and determine second auto drift correction parameters, wherein a second time correction is applied to the intermediate device time to generate a final device time.