Toward ISAC-Inspired WiFi–Radar Fusion for Privacy-Preserving Elderly In-Home Monitoring

Abstract

Population aging is increasing demand for unobtrusive in-home monitoring, while cameras raise privacy concerns, and wearables depend on user compliance. This critical survey and design study compares WiFi channel-state information sensing and millimeter-wave FMCW radar for fall detection, activity recognition, and vital-sign monitoring. It identifies cross-environment generalization, multi-occupant attribution, and privacy evaluation as key barriers to deployment. An ISAC-inspired architecture is proposed that combines broad, low-cost WiFi coverage with radar in high-risk areas and uses cross-modal consistency checking to detect modality-specific unreliability. A controlled synthetic simulation illustrates that this mechanism can prevent an unstable modality from degrading fusion under asymmetric domain shift, but does not establish real-world or clinical performance. The paper also distinguishes among visual, behavioral, and health data privacy and identifies priorities for synchronized datasets, cross-home evaluation, and privacy-aware alert governance.