Positioning System with MIMO Array and Digital Spatial Filter that Tracks Fixed Visible Lights

This letter proposes a visible light indoor position tracker employing a newly developed Angle of Arrival (AOA) with Multiple Input Multiple Output (MIMO) channel model algorithm. The position tracker utilizes indoor illumination lights and a photodiode (PD) array. An adaptive digital spatial filter attached to the output of the PD array performs MIMO signal processing and decomposes the light signals received from different illumination light sources that are simultaneously input to the PD array. The position tracker then estimates the angle of arrival of each light signal and finally its position. This letter demonstrates a position tracker with an adaptive digital filter tunning the Least Mean Square (LMS) algorithm and evaluates its positioning error performance. Experiments show excellent performance as the positioning errors were as low as 0.05 m in an indoor environment with dimensions of $1.75\times 2\times 2\ \mathrm{m}$ .