Indoor Visible Light Localization Algorithm Based on Received Signal Strength Ratio with Multi-Directional LED Array

Visible light communication (VLC) based localization is a potential candidate for indoor localization. However, since the field of view (FOV) of the photodiode (PD) is normally narrow, the PD might not be capable to detect enough LEDs to perform the triangulation algorithm. Furthermore, high directionality is a significant character in VLC, and in practice, the direction of LED is commonly fixed and able to be known for once, but the direction of the PD is commonly random. In this paper, we exploit the direction of the LED in the lamp structure design and manage to mitigate the influence of the direction of the PD in the algorithm design. A localization algorithm based on received signal strength ratio (RSSR) with multi-directional LED array (MDLA) is proposed. In addition, we introduce the coverage ratio (CR) and the average angle acceptance ratio (AAAR) to evaluate the localization scheme's coverage in location and acceptance in direction, respectively. Simulation results show that when the tilt angle of LEDs is 15 degrees, the proposed scheme can attain the root-mean-square error (RMSE) of 0.04 m and 0.06 m in 2-D and 3-D localization, respectively, and it is more probably for it to obtain enough lamps compared to the conventional scheme using the triangulation algorithm with the lamp structure of a single LED.