Efficient phase difference-based visible light positioning system

Visible light (VL) indoor positioning offers significant advantages, such as low cost, high durability, and environmental protection. In this work, a phase difference-based VL positioning (VLP) system is presented. It uses the fast Fourier transform to accelerate the computation of the phase differences between the received signals. Furthermore, unlike most similar published works, it addresses the crucial issue of synchronization that arises in any system based on the time difference of arrival or phase difference and it proposes a technique to solve it. Compared with current indoor positioning methods using light-emitting diode (LED) light, our method has the advantage of having a high positioning accuracy, while being simple to implement and low cost. By means of simulations, we studied the impact on its performance of the choice of its design parameters, such as the values of frequencies assigned to different LEDs, the sampling frequency, the power of noise, and the lack of synchronization. The obtained results show that an appropriate choice of these parameters achieves high-accuracy positioning. Using only three LEDs, an average error of 0.59 cm could be achieved over a testing area of 100 cmx100 cmx160 cm, for a signal-to-noise ratio equal to 15 dB.