Toward Multi-Person Breath Rate Estimation via mmWave Radar

The measurement of breath rate (BR) is essential for comprehensive human health monitoring across a wide range of scenarios. Several studies in the literature have explored the estimation of BR using millimeter wave (mmWave) technology. However, these approaches typically focus on a single subject at a time. To enable multi-person estimation, researchers have often relied on data fusion with camera systems or employed specialized hardware configurations. On the contrary, this paper proposes a methodology that employs only one Frequency Modulated Continuous Wave (FMCW) radar to estimate the BR of multiple subjects stationary in the environment. The proposed methodology includes a pre-processing pipeline to refine the radar-captured signals, followed by frequency-domain analysis to distinguish between subjects. Finally, phase variations in the reflected signals caused by chest movements are analyzed to estimate the BR. Advantages and limitations of the approach are discussed on the basis of an experimental campaign.