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Low-Cost UFSOOK-Based Optical Camera Communication Link for IoT Applications

Internet-of-Things (IoT) solutions require a large number of low-power devices being connected to the internet. Most existing wireless IoT solutions rely on radio frequency (RF) technologies for communication. The RF spectrum is becoming more congested and limited by interference. This motivated researchers to explore new technologies operating at different bands of the spectrum, one of which is the Optical Wireless Communication (OWC) technology. In OWC, a light beam from a laser diode (LD) or a Light Emitting Diode (LED) is modulated and transmitted in the free-space. One of the subfields of OWC technologies is Optical Camera Communication (OCC), in which a camera is used as a receiver to detect the modulated light. The bitrate of an OCC link depends on the frame rate of the receiving camera, and thus any low-cost OCC link will be limited in bitrate. A low bitrate OCC link can be useful for applications in which sensors periodically post lightweight data. In this paper, we develop a low-cost OCC link for energy-constrained IoT devices. We utilize the Undersampled Frequency Shift On-Off Keying (UFSOOK) modulation scheme to modulate a 40 mA LED transmitter used to transmit continuously sensed temperature and humidity data using MQTT to be posted on a dashboard. The performance of the OCC link was comparable to its WiFi counterpart over five days of deployment at the entrance of a lab with research students frequently interrupting the LOS link.