Wireless sensing applications with Wi-Fi Channel State Information, preprocessing techniques, and detection algorithms: A survey

Recently, using Wi-Fi devices as sensing technology has garnered significant attention and found numerous applications. This trend has given birth to what is known as Wi-Fi sensing. This innovative approach has been made possible by analyzing the Channel State Information (CSI) of the Wi-Fi communication channel, which can be calculated from the frame preamble. CSI captures multipath effects, attenuations, and phase shifts in signal propagation, among other fading effects caused, for example, by reflection with objects or a person. Extensive research in this field has revealed that these effects can be utilized for sensing purposes, supposing that the cause of the effects is a person, leading to the development of Wi-Fi sensing applications such as Activity Recognition, Gesture Recognition, and Vital Signs monitoring. This Survey highlights recent works and advances in Wi-Fi sensing applications, identifying and exposing significant applications. For each paper selected, the following sections have been emphasized: Data Collection, Data Preprocessing, Detection Algorithm, Performance, and Application, as these are part of the methodology followed for the functioning of Wi-Fi sensing systems. Furthermore, the techniques and tools commonly used in Wi-Fi sensing are described. Finally, the current challenges associated with Wi-Fi as a wireless sensing technology and possible ways to address these challenges are discussed.