WLAN RTT Geo-location SIFS Mode Correction
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Solution Overview
Problem
Wi-Fi Access Points often use varying Short Interframe Spacing (SIFS) values, leading to inaccurate calculations of distance in wireless local area network (WLAN) device geo-location due to fluctuating Round Trip Time (RTT) measurements.
Innovation Solution
A method and system that utilize a single mobile wireless measuring station to detect and adjust for multiple SIFS modes in target stations, employing kernel density estimation (KDE) and mode correction techniques to align RTT values to a single SIFS mode, ensuring accurate distance calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple SIFS modes are used by target stations, then adaptability of the wireless communication system is improved, but measurement precision of RTT and distance calculation deteriorates
Solution Approach 1:
The patent introduces an intermediary processing system that detects multiple SIFS modes in target stations and applies mode correction to RTT measurements. This intermediary layer separates the adaptability of using multiple SIFS modes from the precision requirement of RTT measurement, allowing both to coexist by translating variable SIFS modes into corrected, consistent RTT values for accurate distance calculation
Solution Approach 2:
The patent changes the parameter interpretation by detecting different SIFS modes and applying corresponding correction factors to RTT measurements. Instead of requiring a fixed SIFS parameter, the system dynamically adjusts the measurement interpretation based on detected modes, transforming the problem from one of parameter consistency to one of parameter adaptation with correction
2Ease of operation
If varying SIFS values are used by Access Points, then ease of operation is improved, but reliability of distance calculation deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the system detects the actual SIFS modes being used by target stations and uses this feedback information to correct RTT measurements. This closed-loop approach maintains reliability by continuously adapting to the actual operating conditions while allowing Access Points the operational freedom to use varying SIFS values
3Measurement precision
If mode correction techniques are applied to align RTT values, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the RTT measurement process into distinct phases: detection of SIFS modes, identification of mode peaks using kernel density estimation, and application of mode correction. This segmentation allows the complex correction process to be broken down into manageable, modular steps that can be implemented systematically without overwhelming system complexity
Data Source
AI summary
A method in a first wireless device (WD) is described. The method includes determining one round trip time (RTT) of a first set of RTTs. The method also includes, at set intervals (TK), determining a set of mode peaks of the first set of RTTs, determining that the first SIFS mode has the highest mode peak of the set of mode peaks, determining that the second SIFS mode has the second highest peak of the set of mode peaks, determining a mode difference (TD), and adjusting the second subset of RTTs at least by adding or subtracting TD to each RTT of the second subset of RTTs. The method also includes determining a second set of RTTs comprising the first subset of RTTs and the adjusted second subset of RTTs, the second set of RTTs corresponding to the adjusted single SIFS mode.