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Indoor Occupancy Estimation Using Visible Light Sensing (VLS) System

In this paper, a new occupancy estimation technique based on visible light sensing (VLS) is presented. A visible light source (e.g., LED) is utilized as the transmitter and a photo-detector (PD) used as a receiver, forming a visible light sensing system. Depending on the number of people in the room crossing the line-of-sight LOS (between the light source and PD), the received power at the receiver change. Consequently, probability density function (PDF) and cumulative distribution function (CDF) of the received power at the receiver change. First, a theoretical analysis of the received power is developed to incorporate the impact of room occupancy on the PDF and CDF of the received power. Second, these received power PDF and CDF expressions are compared with simulation results. Both results are in perfect agreement that verifies the theoretical analysis. In addition, room occupancy estimation is performed by using two methods, namely Kullback-Leibler(KL)-divergence and Euclidean distance. In these methods, the stored PDF of the received power in the database is compared with the measured received power PDF, which reveals the estimated room occupancy. It was shown how a slight variation in room occupancy can dramatically alter the PDF of the received power.