New Paradigm for Contactless Vital Sign Sensing Using UWB Radar and Hybrid Optical Wireless Communications

This work proposes a new paradigm for contactless vital sign sensing that adopts an integrated ultrawideband (UWB) radar and hybrid optical wireless communication (OWC) technologies. The proposed system is composed of a sensor node and a receiver node. The sensor node is responsible for detecting continuous vital sign signals and then transmitting these signals via the hybrid OWC transmitters, which are composed of a visible light communication transmitter and an infrared transmitter. The contactless UWB radar adopts low intermedium frequency demodulation rather than the conventional direct down conversion topology to avoid severe direct current (DC) offset issue. The advantages of this merged configuration do not only help reduce radar complexity but also provide the required modulated signal with vital signs for the subsequent OWC system. Moreover, the receiver node has an OWC receiver module for receiving vital signs that utilizes a photodiode-based receiver with an analog filter and digital signal processing mechanisms. The proposed architecture exhibits the potential to reduce radar complexity and provide new solutions to replace the conventional contact sensing system used in hospitals or nursing homes.