This paper presents a method that estimates the respiratory rate based on the frame capturing of wireless local area networks. The method uses beamforming feedback matrices (BFMs) contained in the captured frames, which is a rotation matrix of channel state information (CSI). BFMs are transmitted unencrypted and easily obtained using frame capturing, requiring no specific firmware or WiFi chipsets, unlike the methods that use CSI. Such properties of BFMs allow us to apply frame capturing to various sensing tasks, e.g., vital sensing. In the proposed method, principal component analysis is applied to BFMs to isolate the effect of the chest movement of the subject, and then, discrete Fourier transform is performed to extract respiratory rates in a frequency domain. Experimental evaluation results confirm that the frame-capture-based respiratory rate estimation can achieve estimation error lower than 3.2 breaths/minute.
High-Fidelity and Location-Robust Respiratory Waveform Monitoring with Single-Antenna WiFi
College of Information Science and Electronic Engineering, Zhejiang University（浙江大学信息与电子工程学院）；Zhejiang Key Laboratory of Multimodal Communication Networks and Intelligent Information Processing（浙江省多模通信网络与智能信息处理重点实验室）；School of Information and Electrical Engineering, Hangzhou City University（杭州城市大学信息与电气工程学院）；College of Computer Science and Technology, Zhejiang University（浙江大学计算机科学与技术学院）
Quality-Aware Framework for Video-Derived Respiratory Signals
Center for Machine Vision and Signal Analysis (CMVS), University of Oulu, Finland（机器视觉与信号分析中心（CMVS）、奥卢大学，芬兰）；Candour Ltd, Oulu, Finland（Candour公司、奥卢，芬兰）
Beamforming Feedback-based Model-Driven Angle of Departure Estimation Toward Legacy Support in WiFi Sensing: An Experimental Study
Graduate School of Informatics, Kyoto University（京都大学信息学研究科）；School of Engineering, Tokyo Institute of Technology（东京工业大学工学院）；Centre of Wireless Communications, University of Oulu（奥卢大学无线通信中心）
Bi-directional Beamforming Feedback-based Firmware-agnostic WiFi Sensing: An Empirical Study
Graduate School of Informatics, Kyoto University（京都大学情报学研究科）；Centre of Wireless Communications, University of Oulu（奥卢大学无线通信中心）；School of Engineering, Tokyo Institute of Technology（东京工业大学工学院）；Department of Integrated Information Technology, Aoyama Gakuin Univeristy（青山学院大学综合信息技术系）
