Anchor Clock Synchronization via Two-Way Message Exchange
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current synchronization methods for anchor clocks in networks, such as NTP, PTP, RBS, and GPS, face limitations in precision and accuracy, particularly in indoor environments and scenarios requiring high localization accuracy, leading to errors in time-difference-of-arrival (TDoA) based localization.
Innovation Solution
A method and apparatus for determining the skew and offset between two clocks based on measured transmit and receive times of two-way transmissions between anchors, using a processor to retrieve and analyze synchronization times, and a tracking server to calculate clock skew and offset pairs, thereby improving anchor-anchor clock synchronization and localization accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional synchronization methods (NTP, PTP, RBS, GPS) are used for anchor clocks, then basic time synchronization is achieved, but synchronization precision and localization accuracy deteriorate due to clock drift errors
Solution Approach 1:
The system implements feedback by continuously monitoring clock drift between anchors through two-way message exchanges and using the measured drift to dynamically adjust synchronization parameters, thereby maintaining high precision over time without external GPS references
Solution Approach 2:
The patent introduces intermediary synchronization messages exchanged between anchors that act as mediators to measure and compensate for clock drift, enabling indirect synchronization without direct connection to external time sources
2Measurement precision
If GPS receivers are co-located with each anchor for synchronization, then global time reference is provided, but device complexity and cost increase
Solution Approach 1:
The patent extracts the GPS receiver requirement from individual anchors and replaces it with a centralized synchronization protocol where anchors exchange timing information mutually, eliminating the need for expensive GPS hardware at each location while maintaining synchronization accuracy
Solution Approach 2:
Instead of using physical GPS receivers at each anchor, the system creates virtual time references through copied and exchanged synchronization messages between anchors, replicating the function of GPS without the hardware overhead
3Ease of manufacture
If PTP or RBS synchronization schemes are used, then hardware timestamps are provided, but synchronization error remains too high for sub-foot localization accuracy
Solution Approach 1:
The system dynamically adjusts synchronization parameters based on measured clock drift characteristics, transitioning from static PTP/RBS approaches to adaptive synchronization that continuously optimizes timing accuracy for the specific network conditions and hardware characteristics
Solution Approach 2:
The patent changes the synchronization parameter from fixed hardware timestamps to dynamically calculated time adjustments based on measured drift, allowing the system to adapt timing parameters to actual performance rather than relying on theoretical hardware precision
Data Source
AI summary
Various embodiments provide a method and apparatus for providing improved anchor-anchor clock synchronization. In particular, the skew and offset of a second clock in reference to a first clock is determined based on measured transmit and receive times of at least two two-way transmissions between a first anchor using the first clock and a second anchor using the second clock.