Beamforming Feedback-Based Line-of-Sight Identification Toward Firmware-Agnostic WiFi Sensing

This study realizes firmware-agnostic line-of-sight (LOS) identification to extend the range of WiFi-sensing applications. We developed a beamforming feedback (BFF)-based LOS identification algorithm. BFF frames are transmitted for multiple-input multiple-output (MIMO) communications. They can be ob...

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Main Authors: Hiroki Shimomura, Koji Yamamoto, Takayuki Nishio, Akihito Taya
Format: Article
Language:English
Published: IEEE 2024-01-01
Series:IEEE Open Journal of Vehicular Technology
Subjects:
Online Access:https://ieeexplore.ieee.org/document/10631655/
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author Hiroki Shimomura
Koji Yamamoto
Takayuki Nishio
Akihito Taya
author_facet Hiroki Shimomura
Koji Yamamoto
Takayuki Nishio
Akihito Taya
author_sort Hiroki Shimomura
collection DOAJ
description This study realizes firmware-agnostic line-of-sight (LOS) identification to extend the range of WiFi-sensing applications. We developed a beamforming feedback (BFF)-based LOS identification algorithm. BFF frames are transmitted for multiple-input multiple-output (MIMO) communications. They can be obtained by capturing frames without custom firmware or specific chipsets and contain a beamforming feedback matrix (BFM) and subcarrier-averaged stream gain (SSG). These provide partial channel state information (CSI), and there are two major calculation steps involved from the CSI to the BFF: unquantized BFF (UQBFF) calculation and quantization. Focusing on the relationship between singular value decomposition and principal component analysis, we numerically demonstrated that the first column vectors of the BFM reflect the LOS/NLOS conditions. Therefore, the proposed BFF-based method extracts features from the first-column vectors of the BFM. In addition, SSGs were leveraged to improve the accuracy. To demonstrate the feasibility of the proposed method, we conducted experiments using commodity off-the-shelf devices compliant with the IEEE 802.11ac standard. In the experimental evaluation, the proposed BFF-based method achieved an identification accuracy of 75.0%, whereas the CSI-based method achieved an accuracy of 81.2%. Accuracy comparisons revealed that the accuracy degradation of the BFF-based identification from the CSI-based identification was primarily caused by UQBFF calculations rather than quantization.
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issn 2644-1330
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publishDate 2024-01-01
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spelling doaj-art-2295fe2e53364885ba3f65af465e6ec62025-01-30T00:04:04ZengIEEEIEEE Open Journal of Vehicular Technology2644-13302024-01-0151024103510.1109/OJVT.2024.344040010631655Beamforming Feedback-Based Line-of-Sight Identification Toward Firmware-Agnostic WiFi SensingHiroki Shimomura0https://orcid.org/0009-0008-7119-745XKoji Yamamoto1https://orcid.org/0000-0003-4106-3983Takayuki Nishio2https://orcid.org/0000-0003-1026-319XAkihito Taya3https://orcid.org/0000-0001-9074-9709Graduate School of Informatics, Kyoto University, Kyoto, JapanFaculty of Information and Human Sciences, Kyoto Institute of Technology, Kyoto, JapanSchool of Engineering, Tokyo Institute of Technology, Tokyo, JapanInstitute of Industrial Science, The University of Tokyo, Tokyo, JapanThis study realizes firmware-agnostic line-of-sight (LOS) identification to extend the range of WiFi-sensing applications. We developed a beamforming feedback (BFF)-based LOS identification algorithm. BFF frames are transmitted for multiple-input multiple-output (MIMO) communications. They can be obtained by capturing frames without custom firmware or specific chipsets and contain a beamforming feedback matrix (BFM) and subcarrier-averaged stream gain (SSG). These provide partial channel state information (CSI), and there are two major calculation steps involved from the CSI to the BFF: unquantized BFF (UQBFF) calculation and quantization. Focusing on the relationship between singular value decomposition and principal component analysis, we numerically demonstrated that the first column vectors of the BFM reflect the LOS/NLOS conditions. Therefore, the proposed BFF-based method extracts features from the first-column vectors of the BFM. In addition, SSGs were leveraged to improve the accuracy. To demonstrate the feasibility of the proposed method, we conducted experiments using commodity off-the-shelf devices compliant with the IEEE 802.11ac standard. In the experimental evaluation, the proposed BFF-based method achieved an identification accuracy of 75.0%, whereas the CSI-based method achieved an accuracy of 81.2%. Accuracy comparisons revealed that the accuracy degradation of the BFF-based identification from the CSI-based identification was primarily caused by UQBFF calculations rather than quantization.https://ieeexplore.ieee.org/document/10631655/Channel state informationbeamforming feedbackfirmware-agnostic WiFi sensingline-of-sight identificationwireless local area networks
spellingShingle Hiroki Shimomura
Koji Yamamoto
Takayuki Nishio
Akihito Taya
Beamforming Feedback-Based Line-of-Sight Identification Toward Firmware-Agnostic WiFi Sensing
IEEE Open Journal of Vehicular Technology
Channel state information
beamforming feedback
firmware-agnostic WiFi sensing
line-of-sight identification
wireless local area networks
title Beamforming Feedback-Based Line-of-Sight Identification Toward Firmware-Agnostic WiFi Sensing
title_full Beamforming Feedback-Based Line-of-Sight Identification Toward Firmware-Agnostic WiFi Sensing
title_fullStr Beamforming Feedback-Based Line-of-Sight Identification Toward Firmware-Agnostic WiFi Sensing
title_full_unstemmed Beamforming Feedback-Based Line-of-Sight Identification Toward Firmware-Agnostic WiFi Sensing
title_short Beamforming Feedback-Based Line-of-Sight Identification Toward Firmware-Agnostic WiFi Sensing
title_sort beamforming feedback based line of sight identification toward firmware agnostic wifi sensing
topic Channel state information
beamforming feedback
firmware-agnostic WiFi sensing
line-of-sight identification
wireless local area networks
url https://ieeexplore.ieee.org/document/10631655/
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