Implementation of a visible light based indoor localization system

This paper reports the practical implementation and the results of a visible light-based indoor localization system employing fingerprinting technique. The localization system consists of four consumer grade LED luminaires that are positioned 2.5 m above a 3.4 m × 2.2 m floor space. A square wave modulation scheme is employed to allow each luminaire to be identified by a photodiode-based receiver using Fast Fourier Transform (FFT). A position within this floor space can be characterized as an ID which is made up of a vector of the detected signal magnitudes of each of the luminaires. By employing the fingerprinting localization methodology, the mobile receiver's position can be located by comparing the ID vector it is currently receiving to a database of known IDs at each position. A mean error of 1.39 cm within a two dimensional floor space is achievable with a system of this scale. The paper also shows how the accuracy can be traded off with the size of the offline database.