UWB RTLS Development for Multipath Environment and Field Test Results

Ultra-wideband (UWB) is a radio technology based on the IEEE 802.15.4a and 802.15.4z standards that enable highly accurate measurement of the Time of Flight (ToF) of the radio signal, leading to centimeter-level distance accuracy measurement [1]. UWB has revolutionized real-time location (RTL) with its high accuracy and positioning capabilities of a few centimeters in both indoor and outdoor environments. The accuracy may degrade if there are multipaths and obstructions between the devices that hinder the line-of-sight (LOS). Since, UWB leverages Time of Flight (ToF) measurement, it manages multipath by detecting the “First Path” rather than the “First Strong Peak” of the received signal [2]. However, the detection of the “First Path” may fail if the signal power is below the noise threshold values. The detection of the “First Path” can be improved by selecting a higher preamble length (PL) and pulse repetition frequency (PRF). The main objectives of this research are to develop a UWB system that can be used for actual deployment in offices, factories, and plants. The system includes a floor map creation tool, UWB anchor setup tool, UWB tags management tool, and a cloud-based database management system to analyze UWB tag data in real-time. The floor map creation tool is used to compute the Anchor coordinates in semi-automatic mode. We found that deployment of UWB Anchors and computation of its coordinates in large numbers in a plant or factory is a challenging task. The accuracy in this study is about 20cm (+/- 10cm) even in the area with multipath in static tests. There are also cases when position data are not available.