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Occupancy Detection Using Wi-Fi in Indoor Environments
KTH, School of Electrical Engineering and Computer Science (EECS).
KTH, School of Electrical Engineering and Computer Science (EECS).
2025 (English)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

Using Wi-Fi to detect occupancy could benefit smart buildings in areas such as energy management or security by utilizing already installed infrastructure. In this study, Channel State Information (CSI) data was processed and used to train machine learning classifiers, specifically Decision Trees and Support Vector Machines (SVM) with a linear kernel, to detect human occupancy in a dynamic office environment. The impact of data normalization, feature count, and varying sliding-window sizes during feature extraction on model performance was also analyzed. The decision tree classifier achieved up to 98% accuracy, while the SVM achieved up to 68%. Data normalization and increasing the number of features beyond a necessary subset were found to reduce model performance and increase training time. In contrast, larger window sizes during feature extraction consistently improved the accuracy and efficiency of the decision tree models. 

Abstract [sv]

Att använda Wi-Fi för att upptäcka närvaro kan gynna smarta byggnader inom områden som energihantering eller säkerhet genom att utnyttja redan installerad infrastruktur. I denna studie bearbetades data från "Channel State Information" (CSI) som användes för att träna maskininlärningsklassificerare, specifikt beslutsträd och stödvektormaskiner (SVM), för att detektera mänsklig närvaro i en dynamisk kontorsmiljö. I studien analyserades även hur datanormalisering, antalet extraherade egenskaper och variationer i glidande fönsterstorlek vid feature extraction påverkade modellernas prestanda. Klassificeraren baserad på beslutsträd uppnådde upp till 98% noggrannhet, medan SVM-modellen nådde upp till 68%. Det visade sig att datanormalisering samt att använda fler egenskaper än nödvändigt försämrade modellernas prestanda och ökade träningstiden. Större fönsterstorlekar vid feature extraction förbättrade däremot konsekvent både noggrannhet och effektivitet hos beslutsträdsmodellen.

Place, publisher, year, edition, pages
2025. , p. 461-465
Series
TRITA-EECS-EX ; 2025:145
Keywords [en]
Occupancy detection, Wi-Fi, Channel State Information (CSI), machine learning, decision trees, support vector machines (SVM), feature extraction, data normalization
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-376167OAI: oai:DiVA.org:kth-376167DiVA, id: diva2:2034533
Supervisors
Examiners
Projects
Kandidatexamensarbete i Elektroteknik 2025, EECS, KTHAvailable from: 2026-02-02 Created: 2026-02-02

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CiteExportLink to record
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  • apa
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