Extracting Heart-Rate Variability Indicators from Wi-Fi CSI: A Pilot Correlation Study

This pilot study evaluates whether Wi-Fi Channel State Information (CSI)-derived micro-movements can reflect autonomic patterns associated with Heart Rate Variability (HRV). CSI-estimated inter-beat intervals were compared with smartwatch-derived HRV metrics during relaxation and mild stress tasks involving 14 volunteers. While absolute HRV values differed, CSI-derived LF/HF variations showed directional alignment with physiological state changes (r = 0.84, p < 0.001), with mean absolute error of 5.8 ms for SDNN and 4.1 ms for RMSSD. Results underscore potential for contactless autonomic monitoring and motivate further clinical investigation, avoiding any claim of diagnostic utility. The findings suggest CSI-based passive wireless analytics may complement existing wearable methods for stress monitoring and autonomic assessment in ecologically valid settings.