Access Point Clock Synchronization via Indirect Offset and Drift Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing clock synchronization methods for access points in wireless networks face challenges due to natural unsynchronization of quartz crystals, temperature variations, age, and clock jitter, leading to uncertainty in spatial solutions, and existing solutions either add complexity and cost with wired synchronization or suffer from unreliability due to wireless medium issues like obstructions and multipath errors.
Innovation Solution
A method and apparatus for synchronizing clocks between access points using direct and indirect calculations of clock offset and drift based on signal exchanges, allowing virtual synchronization through a server that estimates and corrects clock offsets and drift, even in situations where direct packet exchanges are unreliable, by utilizing a communication interface and logic to acquire and process synchronization data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wire-based clock distribution is used between access points, then clock synchronization precision is improved, but deployment complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical/wired clock distribution system with a wireless synchronization system. Instead of physically distributing clock signals through wires between access points, the system uses wireless packet exchanges with timestamp comparisons to achieve clock synchronization, thereby eliminating the need for complex physical infrastructure while maintaining synchronization capability
Solution Approach 2:
The patent introduces a synchronization server as an intermediary that collects timestamp data from multiple access points and calculates clock offset and drift information. This server acts as a central coordinator that enables indirect synchronization between access points that cannot directly synchronize with each other, simplifying the overall system architecture
2Adaptability or versatility
If wireless clock synchronization is used between access points, then deployment flexibility is improved, but synchronization reliability deteriorates due to obstructions and multipath errors
Solution Approach 1:
The patent segments the synchronization problem into direct and indirect synchronization components. Access points attempt direct synchronization through wireless packet exchanges, but when obstructions prevent reliable direct synchronization, the system segments the path and uses the synchronization server as an intermediate node to establish indirect synchronization, ensuring reliability regardless of physical obstacles
Solution Approach 2:
The patent implements a redundant synchronization approach where access points perform both direct wireless synchronization attempts and indirect synchronization through the server. This excessive action ensures that even if direct synchronization fails due to obstructions or multipath errors, the redundant indirect path maintains synchronization reliability
3Measurement precision
If direct packet exchanges are required between all access points for synchronization, then synchronization accuracy is improved, but system complexity and communication overhead increase
Solution Approach 1:
The patent introduces a synchronization server as an intermediary that collects timestamp data from multiple access points and performs the complex offset and drift calculations centrally. This eliminates the need for every access point to directly exchange packets with every other access point, reducing communication overhead and system complexity while maintaining synchronization accuracy through the server's coordinated calculations
Data Source
AI summary
In an example embodiment, a method for synchronizing clocks between a plurality of clocked devices where one of the plurality of clocked devices is not directly synchronized with another of the plurality of clocked devices. Clock offset and a clock drift between a first clock associated with a first device and a second clock associated with a second is directly determined based on signals exchanged between the first and second devices. Clock offset and clock drift between the second clock and a third clock associated with a third device is directly determined based on signals exchanged between the second and third devices. A clock offset and clock drift between the first clock and third clock is determined based on a difference between the clock offset and drift between the first and second clocks and the clock offset and drift between the second and third clocks.