Indoor monitoring system based on ARQ signaling generated by a Visible Light Communication link

Visible Light Communications (VLC) is a candidate technology that complements the benefits of radio communication networks, particularly in those situations where a low-cost solution using license-free spectrum is required to enable ultra-dense deployments of indoor small cells. However, the main drawback that VLC has when compared to wireless communications on RF bands is that, in presence of obstacles between the transmitter and the receiver, full-blockage events are likely to happen as the power received on reflections is much weaker than the power of the blocked line-of-sight link. In this paper, we take advantage of this phenomenon and study the effect that different activities performed by people in the service area to-be-monitored have on the Automatic Repeat reQuest (ARQ) signaling of the VLC link. Based on the presented experimental studies, it is possible to conclude that different relevant events are able to be detected correctly according to the statistics of the ARQ signaling that is collected from the ongoing VLC transmission.