TinySense: Multi-user respiration detection using Wi-Fi CSI signals

Respiration rate plays an important role in human health monitoring. Traditional respiration rate monitoring techniques usually require users to wear some special equipment, which is not convenient for the elderly and the baby. Recently, Wi-Fi based respiration detection technique has attracted much attention due to its device-free and low-deployment-cost. However, most existing studies focus on respiration detection in experimental environments, without considering the impact of people around (it often occurs in our daily life), therefore, if there are several people in the system, their detection will fail. To address this open issue, we propose TinySense, a novel approach that can detect multiple persons' respiration at a time. In particular, we use multiple TX-RX antenna pairs to capture the Wi-Fi Channel State Information (CSI), filter out the data whose time-of-arrival (TOA) is bigger than a truncation threshold and remove subcarriers that are greatly affected by the multi-path effect. As a result, we can obtain the respiration data of each person from the mixed received signal. Experiments demonstrate the effectiveness of our approach on two-user respiration detection.