Automatic Coordinates Estimation for Beacon LEDs in Visible Light Positioning Systems

Visible light positioning is a promising indoor positioning technique for its high accuracy and immunity to radiofrequency interferences. However, it is expensive and time-consuming to manually measure the coordinates of the massive beacon light-emitting diodes (LEDs). We propose a two-step scheme to locate the LEDs automatically. Firstly, the mobile receiver estimates its own coordinates based on the signals of few LEDs with known coordinates; secondly, the receiver samples the signals of the other unknown LEDs, and estimates their coordinates. The signals are all sampled by a photodiode (PD) array, which outputs the angles of arrival of the LED signals. Explicit positioning error expression is derived as a function of the noise terms and the locations of sampling. Simulation results show that the positioning scheme for the LEDs has centimeter-level accuracy with practical transmit powers. The proposed method can construct the database of the massive LED coordinates based on few beacon LEDs, significantly reducing the cost of manual measurements. Both analytical and simulation results show that the accuracy can be improved by properly choosing the transmit powers and the sampling places.