Heart Signal Sensing Using Millimeter-wave OFDM Waveform in FutureG Communications Systems

Future generation (FutureG) wireless communication systems are envisioned to explore the copious bandwidth at millimeter-wave bands with integrated joint communications and sensing (JCAS) to enhance network performance and augment human capabilities. The Channel State Information (CSI) provided through the channel estimation process enables the capture of fine-grained information on scatterers in the environment to discern minute physiological motion, such as heartbeat. This work presents the first heart signal detection via CSI from a millimeter-wave Orthogonal Frequency-Division Multiplexing (OFDM) waveform. Trade-offs between using CSI amplitude and phase and the impact of frequency diversity are analyzed theoretically and confirmed experimentally using a 28 GHz OFDM communications system. Heart rates were successfully detected for three human subjects within 6% of photoplethysmography (PPG) reference, with clear benefits of frequency diversity among OFDM subcarriers.

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