Three-dimensional optical wireless indoor positioning system using location code map based on power distribution of visible light emitting diode

A new indoor three-dimensional (3D) positioning system is proposed based on visible light emitting diode (LED), and is implemented using a location code and a spatial distribution map. Location codes are allocated to each LED as they are transmitted sequentially to the user or object with an optical sensor. Three LEDs form a triangular optical wireless zone, and intensities of the received location codes are unique at all reference points. After the location codes are allocated to the coordinates of all reference points, their spatial distribution map is implemented. The 3D position of a user or object is then obtained using an algorithm based on the spatial distribution map of the location code. A positioning error for a 2D position was measured to be < 3 cm at a physical distance between two adjacent reference points of 5 cm. A 3D positioning error of about 10 cm was observed in the 3D space, with vertical layers at intervals of 10 cm.