Sleep stage estimation method based on state transition using millimeter-wave radar

Due to the excellent advantages of the radar sensor, it is considered to be one of the most potential technologies for the sleep monitoring. In this paper, we propose a sleep stage estimation method based on state transition using frequency-modulated continuous wave (FMCW) millimeter-wave (MMW) radar. The core of the proposed method is to utilize the physiological characteristics of different state transitions during sleep to achieve state transitions for different human targets. Firstly, we conduct signal preprocessing and target detection to determine the presence of the target. Secondly, we extract features from the respiratory rate and body movement to determine the start of sleep and the end time of sleep. Finally, we employ reference thresholds to determine the state transition of sleep for sleep staging. A total of more than 138 nights of data from 10 participants were tested and compared with the Mi Band 6, Mi Band 7, and Huawei Band 6. The results demonstrate the effectiveness of the proposed method.