Visible Light Indoor Positioning System Based On A Rotatable Optical Receiver

As a promising technique for wireless communications, visible light communication has lots of advantages including energy conservation, the absence of electromagnetic interference, and a higher data rate comparing with other wireless communications techniques. A light emitting diode is used to be the light source in the visible light communications, which is not only for illumination but also for data transmission. Nowadays, global positioning system has been mature in outdoor environment, which can achieve high accuracy in outdoor positioning. However, it can not work well in indoor positioning technology as the complicated indoor environment. Hence, combining visible light communications with indoor positioning becomes a popular research field.This paper proposes and experimentally demonstrates a visible light indoor positioning system fashioned with a single transmitter and a single tilted optical receiver. The main contents of the paper include the following three aspects.Firstly, based on the reseach of the visible light indoor positioning systems with multiple transmitters or receivers, the rotatable optical receiver model is provided, which manages the inter-cell interference in the transmitters and the influence of the devices in the receivers. The tilted receiver module is mounted on a rotatable platform and thus, various azimuth angles can be obtained by rotating the platform, which offers a feasible way to perform multiple measurements with different azimuth angles.Secondly, based on the study of LED radiation model, an indoor positioning algorithm using AOA is provided in comparison with the angle gain difference, which can not offer two-dimentional positioning but also three-dimentional localization. What’s more, the characteristics of the algorithm are annalysed and the algorithm is improved to achieve a lower distance error.Finally, set up the proposed visible light indoor positioning system fashioned with a single transmitter and a single tilted receiver. Experimental results show that the average distance error of the proposed system between the real position and the estimate position is less than 25 mm in an indoor environment of 600mm×600mm×1135mm, which is in good agreement with the simulations. This work indicates that the proposed compact system has high accuracy, which is a new solution for visible light indoor positioning.