Interference mitigation for indoor proximity-based visible light positioning using receiver's angle diversity

Abstract

This work considers proximity-based indoor visible light positioning (VLP) in which the user location is specified through the coordinate of the closest light emitting diode (LED) light source. For applications with human users, tilting of a handheld receiver device may lead to positioning errors due to signal interference from an adjacent LED light source. This work investigates the use of multiple photodiodes (PDs) with angular diversity to improve the positioning accuracy in the presence of receiver's tilting, with a unique focus on using multiple PDs to mitigate the problem of signal interference instead of widening the coverage of each LED. First, it is argued that at least four PDs are required on a pyramid structure to effectively mitigate signal interference. Then, performance analysis in terms of the positioning error probability is presented, to be followed by results on the outage percentage defined as the percentage of receiver positions at which positioning error probabilities exceed some acceptable threshold. After evaluating error performances, the error probability expressions are used to optimize the orientation angle of the PDs attached to a pyramid structure. Finally, hardware experiments are conducted to validate the proposed approach.