An Indoor NLOS Visible Light Positioning Method Based on a Multipixel Photon Counter

Visible light positioning (VLP) is one of the effective solutions for low-cost and high-precision indoor positioning due to its advantages of low cost, high energy efficiency, and immunity from radio frequency induced electromagnetic interference. However, severe performance limitations in occluded environments present a major challenge for the development of VLP. We propose a non-line-of-sight (NLOS) VLP system based on a multipixel photon counter (MPPC) to solve the problem of obstructed line-of-sight (LOS) paths. MPPC consists of multiple avalanche photodiodes operating in Geiger mode, which has very high sensitivity, excellent photon counting capability and can perform detection of very weak light at photon counting levels. It can effectively improve the recognition and detection of signals in NLOS environments. Using the NLOS channel model, we innovatively propose a NLOS-MPPC-VLP positioning theory, which utilizes the NLOS optical signals received by the MPPC to construct the relationship between the received signal strength and the distance from the MPPC to the virtual images of the light emitting diode (LED). Through this theory, the trilateration algorithm is used to calculate the position of the receiver. The experimental results show that the average positioning errors for the proposed system are 8.77 and 10.15 cm for 70 and 100-cm MPPC heights, respectively.