Description

Feature extraction is the umbrella for transforming raw CSI windows into a vector representation suitable for downstream models — either by hand-crafted statistics (subcarrier-features) or by a learned encoder (cnn, transformer-attention). The thesis uses the term to distinguish "what representation are we feeding" from "what classifier consumes it", because the representation choice dominates cross-domain accuracy.

When it's used

  • Pipeline-design discussions of CSI representations
  • Comparing hand-crafted vs learned features
  • Defining the boundary between sensing and inference layers

Limitations

  • Hand-crafted features under-perform learned encoders on rich CSI data
  • Learned features rarely transfer cleanly without domain-adaptation
  • Feature-importance interpretation is hard for deep encoders

Source Papers

  • hou2023_bf83 — feature-extraction comparison for few-shot CSI
  • wang2026_2758 — feature-extraction strategies in WiFi sensing
  • bin2008_8bb7 — early feature extraction for crowd analysis
  • logah2026_c3bb — feature-extraction for CSI HAR
  • chen2023_5cbd — feature-extraction in generalisation taxonomy

30 vault papers use this method

Titles and DOIs only — no abstracts, no analyses.

  • WiFi Sensing with Channel State Information 2020 DOI ↗
  • Device-free occupancy detection and crowd counting in smart buildings with WiFi-enabled IoT 2018 DOI ↗
  • Wi-CaL: WiFi Sensing and Machine Learning Based Device-Free Crowd Counting and Localization 2022 DOI ↗
  • Towards Environment Independent Device Free Human Activity Recognition 2018 DOI ↗
  • A Survey on Human Behavior Recognition Using Channel State Information 2019 DOI ↗
  • Cross-Domain WiFi Sensing with Channel State Information: A Survey 2023 DOI ↗
  • DASECount: Domain-Agnostic Sample-Efficient Wireless Indoor Crowd Counting via Few-Shot Learning 2023 DOI ↗
  • WiFi CSI-Based Device-free Multi-room Presence Detection using Conditional Recurrent Network 2021 DOI ↗
  • A Survey on Wi-Fi Sensing Generalizability: Taxonomy, Techniques, Datasets, and Future Research Prospects 2026 DOI ↗
  • A Non Intrusive Human Presence Detection Methodology Based on Channel State Information of Wi-Fi Networks 2023 DOI ↗
  • Building occupancy estimation and detection: A review 2018 DOI ↗
  • Data-driven Crowd Modeling Techniques: A Survey 2022 DOI ↗
  • CrossSense: Towards Cross-Site and Large-Scale WiFi Sensing 2018 DOI ↗
  • CrossSense: Towards Cross-Site and Large-Scale WiFi Sensing 2018 DOI ↗
  • CrossSense: Towards Cross-Site and Large-Scale WiFi Sensing 2018 DOI ↗
  • CrossSense: Towards Cross-Site and Large-Scale WiFi Sensing 2018 DOI ↗
  • Accurate occupancy estimation with WiFi and bluetooth/BLE packet capture 2019 DOI ↗
  • WiFi-Based Human Sensing With Deep Learning: Recent Advances, Challenges, and Opportunities 2024 DOI ↗
  • Simultaneous Crowd Estimation in Counting and Localization Using WiFi CSI 2021 DOI ↗
  • A Survey on Fusion-Based Indoor Positioning 2020 DOI ↗
  • A low-cost BLE-based distance estimation, occupancy detection and counting system 2021 DOI ↗
  • Human Activity Recognition via Wi-Fi and Inertial Sensors With Machine Learning 2024 DOI ↗
  • A Survey on Green Wireless Sensing: Energy-Efficient Sensing via WiFi CSI and Lightweight Learning 2026 DOI ↗
  • A survey on CSI-based Wi-Fi sensing datasets and models with a focus on reproducibility 2026 DOI ↗
  • IoT solutions for e-Health applications for care's continuity at home 2026 DOI ↗
  • Implementing Wi-Fi CSI-based room-level occupancy Estimation: an experimental study in multi-zone residential environments 2025 DOI ↗
  • RSSI-Assisted CSI-Based Passenger Counting with Multiple Wi-Fi Receivers 2025 DOI ↗
  • Round trip time meets transformers: high-fidelity human counting in cluttered environments 2025 DOI ↗
  • Device-Free Wireless Sensing for Gesture Recognition Based on Complementary CSI Amplitude and Phase 2024 DOI ↗
  • WiGNN: WiFi-Based Cross-Domain Gesture Recognition Inspired by Dynamic Topology Structure 2024 DOI ↗