Wireless Distance Measurement Correction for Multipath RTT Errors
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Solution Overview
Problem
Existing wireless networks face inaccuracies in distance measurements due to multipath interference, leading to errors in determining the location of wireless access points, which is time-consuming and costly to correct manually.
Innovation Solution
A system uses polynomial relationships and channel state information to correct Round Trip Time (RTT) and Received Signal Strength Indicator (RSSI) measurements by determining coefficients that account for multipath errors, selecting measurements with acceptable multipath levels, and applying corrections to improve location accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual surveys are used to correct access point locations, then location accuracy can be improved, but deployment time and costs increase
Solution Approach 1:
The system performs self-correction of access point location measurements by automatically detecting multipath errors and applying corrections without requiring manual surveyor intervention. The access points themselves generate the correction data through their normal operation, eliminating the need for external correction services.
Solution Approach 2:
The patent replaces manual mechanical surveying methods with an automated electronic system that uses signal processing and polynomial corrections. Instead of physical measurement tools and human operators, the system uses computational algorithms to detect and correct location errors automatically.
2Measurement precision
If polynomial corrections are applied to RTT measurements, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system changes the parameters of RTT measurements by applying polynomial transformations to correct for multipath errors. Instead of modifying the physical measurement process, the patent transforms the measurement data mathematically to eliminate errors, maintaining system simplicity while improving accuracy.
3Measurement precision
If channel state information is used to detect multipath, then measurement precision is improved, but information processing requirements increase
Solution Approach 1:
The system extracts only the essential multipath error characteristics from channel state information without processing the entire data set. By isolating and removing the harmful multipath components from the signal analysis, the system improves measurement accuracy while minimizing the processing burden.
Data Source
AI summary
In an example, a method includes obtaining a first plurality of distance measurements for each of a plurality of wireless signals transmitted between a first wireless device and a second wireless device, wherein a distance between the first wireless device and the second wireless device is known; determining coefficients of a polynomial function describing a relationship between estimate errors introduced to the obtained first plurality distance measurements by multipath signals and a statistical spread of the obtained first plurality of distance measurements; obtaining a second plurality of distance measurements for each of a plurality of wireless signals transmitted between a third wireless device and a fourth wireless device, wherein a distance between the third wireless device and the fourth wireless device is unknown; and correcting each of the second plurality of distance measurements based on the determined coefficients of the polynomial function.