Adaptive Fine Timing Measurement Ranging Variance Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
FTM ranging accuracy is compromised in indoor environments due to signal reflections and variations in signal strength and directionality, leading to inaccurate distance and direction estimates between user devices and access points.
Innovation Solution
An access point calculates the variance of estimated distances and instructs the user device to perform remedial actions, such as reducing communication rate, switching to a different radio or channel, or connecting to a different access point, based on predefined thresholds to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FTM ranging bursts are exchanged in indoor environments, then distance estimation can be performed, but signal reflections off walls cause the access point to receive components at different times with different signal strengths, reducing measurement accuracy
Solution Approach 1:
The access point calculates variance of multiple distance estimates and uses this feedback to determine whether to request additional FTM bursts or provide location information to the client device, creating a closed-loop system that adapts to signal quality conditions
Solution Approach 2:
The system exchanges multiple FTM ranging bursts beyond the single burst traditionally used, performing excessive measurements to overcome signal reflection issues through statistical processing of multiple samples
2Measurement precision
If multiple FTM ranging bursts are exchanged to improve accuracy, then measurement precision improves, but the time required for distance estimation increases
Solution Approach 1:
The system dynamically adjusts the number of FTM bursts exchanged based on calculated variance - if variance is below threshold, additional bursts are requested; if variance exceeds threshold, location information is provided instead, creating an adaptive time-cost structure
Data Source
AI summary
A method includes estimating distances between a user device and an access point based on a series of FTM ranging bursts exchanged between the user device and the access point. The method also includes calculating a variance of the estimated distances and in response to determining that the variance exceeds a threshold, instructing the user device to perform an action that reduces the variance. Other embodiments include a device that performs this method.