ULoc

Abstract

A myriad of IoT applications, ranging from tracking assets in hospitals, logistics, and construction industries to indoor tracking in large indoor spaces, demand centimeter-accurate localization that is robust to blockages from hands, furniture, or other occlusions in the environment. With this need, in the recent past, Ultra Wide Band (UWB) based localization and tracking has become popular. Its popularity is driven by its proposed high bandwidth and protocol specifically designed for localization of specialized "tags". This high bandwidth of UWB provides a fine resolution of the time-of-travel of the signal that can be translated to the location of the tag with centimeter-grade accuracy in a controlled environment. Unfortunately, we find that high latency and high-power consumption of these time-of-travel methods are the major culprits which prevent such a system from deploying multiple tags in the environment. Thus, we developed ULoc, a scalable, low-power, and cm-accurate UWB localization and tracking system. In ULoc, we custom build a multi-antenna UWB anchor that enables azimuth and polar angle of arrival (henceforth shortened to '3D-AoA') measurements, with just the reception of a single packet from the tag. By combining multiple UWB anchors, ULoc can localize the tag in 3D space. The single-packet location estimation reduces the latency of the entire system by at least 3×, as compared with state of art multi-packet UWB localization protocols, making UWB based localization scalable. ULoc's design also reduces the power consumption per location estimate at the tag by 9×, as compared to state-of-art time-of-travel algorithms. We further develop a novel 3D-AoA based 3D localization that shows a stationary localization accuracy of 3.6 cm which is 1.8× better than the state-of-the-art two-way ranging (TWR) systems. We further developed a temporal tracking system that achieves a tracking accuracy of 10 cm in mobile conditions which is 4.3× better than the state-of-the-art TWR systems.

Bidirectional UWB Localization: A Review on an Elastic Positioning Scheme for GNSS-Deprived Zones

“…The localization process of range-based positioning systems can be organized into two phases, namely: (i) the signal measurement phase (i.e., the ranging process mentioned above) and (ii) the location estimation phase (i.e., estimating a location of a moving target using positioning algorithm and the measured ranges in the former phase). Measurement in the former phase is commonly carried out using time of arrival (ToA) [30], [31], TDoA [32], angle of arrival (AOA) [33], [34] or received signal strength (RSS) [2], [35] techniques. Particularly for time-based UWB localization [36], the ToA and TDoA techniques are the classical choice for establishing the system implementation process.…”

“…In contrast, the RSS approach is rarely used in UWB localization due to its poorer performance compared to the other techniques mentioned [8]. Likewise, the AoA method does not receive as good awareness as its counterpart ToA and TDoA approaches due to the necessity of a more complex system setup such as antenna arrays and beamforming techniques [34], [37].…”

GPSMirror: Expanding Accurate GPS Positioning to Shadowed and Indoor Regions with Backscatter

“…Wireless indoor positioning systems, such as Bluetooth low energy (BLE) [6,8,23], ultra-wide-band (UWB) [10,11,41,55], and WiFi [22,24], have demonstrated high precision for indoor localization. However, such specialized infrastructures entail laborious mapping and calibration at the deployment phase and also require a power supply for continuous positioning.…”

A Four Element Stringray-Shaped MIMO Antenna System for UWB Applications

“…Its broad bandwidth and emission of short pulses empower precise and high-resolution imaging, rendering it apt for various medical non-invasive and non-contacting test endeavors. In medical imaging, UWB promises detailed, real-time images conducive to early cancer detection and monitoring [9,10]. It affords precise material inspections in non-destructive testing applications, finding relevance in the aerospace and construction industries.…”