Robust Respiration Detection Based on Intelligent Reflecting Surfaces.

In recent years, contactless respiratory monitoring using commercial WiFi devices has garnered great interest. However, existing methods typically require the person to directly face the WiFi device. When the body is oriented sideways or with the back toward the device, the signals reflected by the chest cavity are weakened, making respiratory monitoring difficult. To address this problem, we propose a novel respiratory monitoring system based on intelligent reflecting surfaces (IRS). The system utilizes the IRS to manipulate wireless signal propagation in the environment and enhance body reflection, finally achieving posture-resilient respiratory monitoring. Moreover, the system is easy to deploy without requiring prior knowledge of exact antenna locations or environmental features. Experiments validate that, compared to previous methods, the system significantly improves respiratory monitoring across various postures in the indoor environment.