On Tracking the Physicality of Wi-Fi: A Subspace Approach

Wi-Fi channel state information (CSI) has emerged as a plausible modality for sensing different human activities as a function of modulations in the wireless signal that travels between wireless devices. Until now, most research has taken a statistical approach and/or purpose-built inference pipelin...

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Main Authors: Mohammed Alloulah, Anton Isopoussu, Chulhong Min, Fahim Kawsar
Format: Article
Language:English
Published: IEEE 2019-01-01
Series:IEEE Access
Subjects:
Online Access:https://ieeexplore.ieee.org/document/8636492/
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spelling doaj-be0fcdeaa8b54390a1e467f7a45b5b4a2021-03-29T22:33:44ZengIEEEIEEE Access2169-35362019-01-017199651997810.1109/ACCESS.2019.28978408636492On Tracking the Physicality of Wi-Fi: A Subspace ApproachMohammed Alloulah0https://orcid.org/0000-0003-3724-7333Anton Isopoussu1Chulhong Min2Fahim Kawsar3Nokia Bell Labs, Cambridge, U.KNokia Bell Labs, Cambridge, U.KNokia Bell Labs, Cambridge, U.KNokia Bell Labs, Cambridge, U.KWi-Fi channel state information (CSI) has emerged as a plausible modality for sensing different human activities as a function of modulations in the wireless signal that travels between wireless devices. Until now, most research has taken a statistical approach and/or purpose-built inference pipeline. Although interesting, these approaches struggle to sustain sensing performances beyond experimental conditions. As such, the full potential of CSI as a general-purpose sensing modality is yet to be realized. We argue that a universal approach with the well-grounded formalization is necessary to characterize the relationship between the wireless channel modulations (spatial and temporal) and human movement. To this end, we present a formalism for quantifying the changing part of the wireless signal modulated by human motion. Grounded in this formalization, we then present a new subspace tracking technique to describe the channel statistics in an interpretable way, which succinctly contains the human modulated part of the channel. We characterize the signal and noise subspaces for the case of uncontrolled human movement and show that these subspaces are dynamic. Our results demonstrate that the proposed channel statistics alone can robustly reproduce the state-of-the-art application-specific feature engineering baseline, however, across multiple usage scenarios. We expect that our universal channel statistics will yield an effective general-purpose featurization of wireless channel measurements and will uncover opportunities for applying CSI for a variety of human sensing applications in a robust way.https://ieeexplore.ieee.org/document/8636492/Channel sensinginterpretable dimensionality reductionmachine learningmultiple-input multiple-output (MIMO)
collection DOAJ
language English
format Article
sources DOAJ
author Mohammed Alloulah
Anton Isopoussu
Chulhong Min
Fahim Kawsar
spellingShingle Mohammed Alloulah
Anton Isopoussu
Chulhong Min
Fahim Kawsar
On Tracking the Physicality of Wi-Fi: A Subspace Approach
IEEE Access
Channel sensing
interpretable dimensionality reduction
machine learning
multiple-input multiple-output (MIMO)
author_facet Mohammed Alloulah
Anton Isopoussu
Chulhong Min
Fahim Kawsar
author_sort Mohammed Alloulah
title On Tracking the Physicality of Wi-Fi: A Subspace Approach
title_short On Tracking the Physicality of Wi-Fi: A Subspace Approach
title_full On Tracking the Physicality of Wi-Fi: A Subspace Approach
title_fullStr On Tracking the Physicality of Wi-Fi: A Subspace Approach
title_full_unstemmed On Tracking the Physicality of Wi-Fi: A Subspace Approach
title_sort on tracking the physicality of wi-fi: a subspace approach
publisher IEEE
series IEEE Access
issn 2169-3536
publishDate 2019-01-01
description Wi-Fi channel state information (CSI) has emerged as a plausible modality for sensing different human activities as a function of modulations in the wireless signal that travels between wireless devices. Until now, most research has taken a statistical approach and/or purpose-built inference pipeline. Although interesting, these approaches struggle to sustain sensing performances beyond experimental conditions. As such, the full potential of CSI as a general-purpose sensing modality is yet to be realized. We argue that a universal approach with the well-grounded formalization is necessary to characterize the relationship between the wireless channel modulations (spatial and temporal) and human movement. To this end, we present a formalism for quantifying the changing part of the wireless signal modulated by human motion. Grounded in this formalization, we then present a new subspace tracking technique to describe the channel statistics in an interpretable way, which succinctly contains the human modulated part of the channel. We characterize the signal and noise subspaces for the case of uncontrolled human movement and show that these subspaces are dynamic. Our results demonstrate that the proposed channel statistics alone can robustly reproduce the state-of-the-art application-specific feature engineering baseline, however, across multiple usage scenarios. We expect that our universal channel statistics will yield an effective general-purpose featurization of wireless channel measurements and will uncover opportunities for applying CSI for a variety of human sensing applications in a robust way.
topic Channel sensing
interpretable dimensionality reduction
machine learning
multiple-input multiple-output (MIMO)
url https://ieeexplore.ieee.org/document/8636492/
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