Hybrid Passive–Active Optical Wireless Transmission for Health Monitoring System

Abstract

This paper proposes a hybrid passive-active optical wireless transmission scheme for personal health monitoring system. In this scheme, passive and active optical wireless transmission is applied in order to attain the required signal to noise ratio (SNR). In passive transmission, thin film corner cube retroreflector (TCCR) is employed to modulate and reflect the obtained measurements from sensors to a central node. The absorbed power from TCCR helps recharge the battery in a wearable transmitter. The active transmission mode is applied when SNR of passive transmission mode cannot be achieved. An image sensor is utilized as a receiver. Absorbed power and reflected power at TCCR and SNR at the image sensor are analyzed with consideration of the transmitted power and the user's location. The analytical results indicate that by employing the hybrid passive-active optical wireless transmission scheme, the required SNR of 13.6 dB is achieved with energy efficiency.