  This paper presents a novel pipeline for vital sign monitoring using a 26 GHz
multi-beam communication testbed. In context of Joint Communication and Sensing
(JCAS), the advanced communication capability at millimeter-wave bands is
comparable to the radio resource of radars and is promising to sense the
surrounding environment. Being able to communicate and sense the vital sign of
humans present in the environment will enable new vertical services of
telecommunication, i.e., remote health monitoring. The proposed processing
pipeline leverages spatially orthogonal beams to estimate the vital sign -
breath rate and heart rate - of single and multiple persons in static scenarios
from the raw Channel State Information samples. We consider both monostatic and
bistatic sensing scenarios. For monostatic scenario, we employ the phase
time-frequency calibration and Discrete Wavelet Transform to improve the
performance compared to the conventional Fast Fourier Transform based methods.
For bistatic scenario, we use K-means clustering algorithm to extract
multi-person vital signs due to the distinct frequency-domain signal feature
between single and multi-person scenarios. The results show that the estimated
breath rate and heart rate reach below 2 beats per minute (bpm) error compared
to the reference captured by on-body sensor for the single-person monostatic
sensing scenario with body-transceiver distance up to 2 m, and the two-person
bistatic sensing scenario with BS-UE distance up to 4 m. The presented work
does not optimize the OFDM waveform parameters for sensing; it demonstrates a
promising JCAS proof-of-concept in contact-free vital sign monitoring using
mmWave multi-beam communication systems.
