Multiperson Respiration Detection: A Digital Programmable Metasurface Analysis Approach

The rapid development of wireless sensing technology has opened new possibilities for noncontact health monitoring. Among them, respiration is crucial information for assessing vital signs. However, traditional methods face challenges of signal interference and overlap in multiperson environments. In this work, we propose a novel method for multiperson respiration detection using a digital programmable metasurface (DPM). This method takes advantage of the modulation characteristics of the DPM in the time and space domain. It divides the channel state information (CSI) from the Wi-Fi transmitter into multiple subsignals in the time domain and modulates the radiation directions of the subsignals for space redistribution. These signals are received by the Wi-Fi receiver and recombined to restore the CSI in each direction, thus enabling the accurate extraction of respiration signals from targets in different directions. Experimental results show that this method can directionally sense the human respiration information in a specific direction under the static working mode. Under dynamic scanning mode, it can effectively separate and detect the respiration information of four people from different directions. This system has great potential for applications in wireless communication, healthcare, and smart home environments.