An Experimental Characterization of Time Synchronization in Multiple UWB Location Cells

Abstract

In recent years, the Internet of Things (IoT) paradigm has enabled increased data generation in plants, forming the basis for the fourth industrial revolution. Some of these applications also require the information to be precisely located in space. This is possible with Real-Time Location Systems (RTLS). One of the most promising RTLS solutions for industrial applications is based on the use of Ultra-Wide Band (UWB) technology and the Time Differential of Arrival (TDoA) technique. Given the coverage limits of UWB technology, a RTLS is generally composed by different location cells. However, in order to achieve the required localization accuracy, the RTLS infrastructure has to be precisely time synchronized (i.e., with an accuracy of less than a nanosecond). The problem of time synchronization in multiple location cells is analyzed and modeled in this work. An experimental RTLS network formed by nodes equipped with Qorvo DWM3000 modules, organized in multiple location cells, has been realized and characterized. The considered UWB modules offer some hardware functionalities, such as estimating clock frequency drift, which can also be used for time synchronization, limiting the need to exchange synchronization packets. However, due to the limited resolution of the involved registers, the experimental characterization revealed that the accuracy obtained using these resources is approximately ten times lower than that obtained using a traditional synchronization protocol.