Efficient Visible Light Sensing in Eigenspace

Due to the wide deployment of light-emitting diode for indoor illumination, a secure and highly sensitive visible light sensing (VLS) technology can be adopted for situation awareness in smart building management and channel update in visible-light communication. Based on existing lighting devices, a device-free VLS system with the photodetectors on the ceiling is proposed. Since any kind of activity may lead to the change of indoor channel matrix, a real-time window matrix is constructed to sense the indoor activity, and random matrix theory is employed, where the likelihood-ratio test (LRT) and mean spectral radius (MSR) serve as the system variation indicators. We compare the average sensing error rates of LRT detection and MSR detection with that of average intensity variation detection on people movement, which show the performance gain of the proposed eigenspace detection approaches. An efficient VLS can also be used to balance the communication performance and channel update overhead.