Doubling the Accuracy of Indoor Positioning: Frequency Diversity
Name
sensors-20-01489.pdf
Size
3.46 MB
Format
Adobe PDF
Checksum (MD5)
52b885136127de3b4fdc21ce8afffa81
Author(s)
Horn, Berthold K. P.
Date Issued
March 2020
Journal
Sensors
Publisher
MDPI AG
Citation
Horn, Berthold K. P. "Doubling the Accuracy of Indoor Positioning: Frequency Diversity." Sensors 20, 5 (March 2020): 1489 © 2020 Author
Version
Final published version
Abstract
Determination of indoor position based on fine time measurement (FTM) of the round trip time (RTT) of a signal between an initiator (smartphone) and a responder (Wi-Fi access point) enables a number of applications. However, the accuracy currently attainable—standard deviations of 1–2 m in distance measurement under favorable circumstances—limits the range of possible applications. An emergency worker, for example, may not be able to unequivocally determine on which floor someone in need of help is in a multi-story building. The error in position depends on several factors, including the bandwidth of the RF signal, delay of the signal due to the high relative permittivity of construction materials, and the geometry-dependent “noise gain” of position determination. Errors in distance measurements have unusal properties that are exposed here. Improvements in accuracy depend on understanding all of these error sources. This paper introduces “frequency diversity,” a method for doubling the accuracy of indoor position determination using weighted averages of measurements with uncorrelated errors obtained in different channels. The properties of this method are verified experimentally with a range of responders. Finally, different ways of using the distance measurements to determine indoor position are discussed and the Bayesian grid update method shown to be more useful than others, given the non-Gaussian nature of the measurement errors.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Terms of Use
Creative Commons Attribution 4.0 International license
Persistent DSpace Link
DOI of Published Version
http://dx.doi.org/10.3390/s20051489
