Beacon LED Coordinates Estimator With Selected AOA Estimators for Visible Light Positioning Systems

The coordinates of beacon light-emitting diodes (LEDs) are assumed as known prior information in most visible light positioning (VLP) systems. However, such an assumption may be unpractical because the structures of the buildings change unpredictably due to the material aging or the changes of temperature and humidity. Therefore, a periodical update of the LEDs' coordinates is necessary for accurate VLP. When the number of beacon LEDs increases, the manual measurement becomes too time-consuming and laborious. In this paper, we propose a novel LED coordinates estimator exploiting arbitrary number of angle-of-arrival (AOA) estimators. Each AOA estimator contains several differently oriented photodiodes (PDs) to detect the incident light direction. Considering the PDs' thermal noises, a closed-form error expression is derived for the proposed LED coordinates estimator. Moreover, AOA estimator selection methods are proposed to detect the AOA estimators of a low signal-to-noise ratio (SNR) and improve the positioning accuracy of the LED coordinates. Analytical and simulation results show centimeter-level positioning accuracy, and verify that the selection methods can reduce the positioning error.