Sepideh Mohammadi Kouhini, Christoph Kottke, Ziyan Ma, Ronald Freund, Volker Jungnickel, Marcel Müller, Daniel Behnke, Marcos Martinez Vazquez, and Jean-Paul Linnartz, “LiFi Positioning for Industry 4.0”, Journal of Scelected Topics in Quatum Electronics (JSTQE), 2021

Abstract: Precise position information is considered as the main enabler for the implementation of smart manufacturing systems in Industry 4.0. In this article, a time-of-flight based indoor positioning system for LiFi is presented based on the ITUT recommendation G.9991. Our objective is to realize positioning by reusing already existing functions of the LiFi communication protocol which has been adopted by several vendors. Our positioning algorithm is based on a coarse timing measurement using the frame synchronization preamble, similar to the ranging, and a
fine timing measurement using the channel estimation preamble. This approach works in various environments and it requires neither knowledge about the beam characteristics of transmitters
and receivers nor the use of fingerprinting. The new algorithm is validated through both, simulations and experiments. Results in an 1m1m2m area indicate that G.9991-based positioning can reach an average distance error of a few centimeters in three dimension. Considering the common use of lighting in indoor environments and the availability of a mature optical wireless  communication system using G.9991, the proposed LiFi positioning is a promising new feature that can be added to the existing protocols and enhance the capabilities of smart lighting systems further for the benefit of Industry 4.0.