20 research outputs found
Reducing Two-Way Ranging Variance by Signal-Timing Optimization
Time-of-flight-based range measurements among transceivers with different
clocks requires ranging protocols that accommodate for the varying rates of the
clocks. Double-sided two-way ranging (DS-TWR) has recently been widely adopted
as a standard protocol due to its accuracy; however, the precision of DS-TWR
has not been clearly addressed. In this paper, an analytical model of the
variance of DS-TWR is derived as a function of the user-programmed response
delays. Consequently, this allows formulating an optimization problem over the
response delays in order to maximize the information gained from range
measurements by addressing the effect of varying the response delays on the
precision and frequency of the measurements. The derived analytical variance
model and proposed optimization formulation are validated experimentally with 2
ranging UWB transceivers, where 29 million range measurements are collected.Comment: 5 pages, 4 figures, submitted to 2023 International Conference on
Acoustics, Speech and Signal Processing (ICASSP
A Generalized TDoA/ToA Model for ToF Positioning
Many applications require positioning. Time of Flight (ToF) methods calculate
distances by measuring the propagation time of signals. We present a novel ToF
localization method. Our new approach works infrastructure-less, without
pre-defined roles like Anchors or Tags. It generalizes existing
synchronization-less Time Difference of Arrival (TDoA) and Time of Arrival
(ToA) algorithms. We show how known algorithms can be derived from our new
method. A major advantage of our approach is that it provides a comparable or
better clock error robustness, i.e. the typical errors of crystal oscillators
have negligible impact for TDoA and ToA measurements. We show that our channel
usage is for most cases superior compared to the state-of-the art.Comment: Published in IEEEXplore:
https://ieeexplore.ieee.org/abstract/document/891174
Supplementary Data for the Paper entitled ''An Analytical Study of Time of Flight Error Estimation in Two-Way Ranging Methods''
Lian Sang C, Adams M, Hörmann T, Hesse M, Porrmann M, Rückert U. Supplementary Data for the Paper entitled ''An Analytical Study of Time of Flight Error Estimation in Two-Way Ranging Methods''. Bielefeld University; 2018.The contents of this publication are intended for providing additional supplementary materials, i.e. proofs of formula derivations, presented in our paper entitled "An Analytical Study of Time of Flight Error Estimation in Two-Way Ranging Methods". The mentioned paper was submitted to ``Ninth International Conference on Indoor Positioning and Indoor Navigation (IPIN) 2018}'', which will be held in Nantes, France on September 24-27, 2018
Ultra-Wideband Technology: Characteristcs, Applications and Challenges
Ultra-wideband (UWB) technology is a wireless communication technology
designed for short-range applications. It is characterized by its ability to
generate and transmit radio-frequency energy over an extensive frequency range.
This paper provides an overview of UWB technology including its definition, two
representative schemes and some key characteristics distinguished from other
types of communication. Besides, this paper also analyses some widely used
applications of UWB technology and highlights some of the challenges associated
with implementing UWB in real-world scenarios. Furthermore, this paper expands
upon UWB technology to encompass terahertz technology, providing an overview of
the current status of terahertz communication, and conducting an analysis of
the advantages, challenges, and certain corresponding solutions pertaining to
ultra-wideband THz communication
Indoor Localization System With NLOS Mitigation Based on Self-Training
Location-awareness has become a fundamental requirement for multiple emerging applications with the rapid development
of wireless technologies. The high-accuracy ranging enabled by ultra-wide bandwidth (UWB) signals is often deteriorated by clocks
imperfections and non-line-of-sight (NLOS) propagation. Existing supervised learning methods for NLOS identification and mitigation
are time-consuming, labor-intensive, and cost-inefficient due to the need for training data acquisition and label assignment. This paper
presents an indoor localization system that enables NLOS mitigation based on self-training. The system provides a general information
fusion framework that integrates map, inertial sensors, and UWB measurements, where the weak labels for UWB measurements are
produced and iteratively refined by multi-sensory information fusion for self-training. In addition, the system utilizes the maximum
likelihood ranging estimator that considers the impact of clock drift. The effectiveness of the proposed system is demonstrated via
extensive experimentation in multiple real-world environments, e.g., the proposed methods reduce the NLOS ranging error by 80% and
result in a 90th localization error percentile of 0.5 meters in a complex indoor environment
Analysis and Accuracy Improvement of UWB-TDoA-Based Indoor Positioning System
Positioning systems are used in a wide range of applications which require determining the position of an object in space, such as locating and tracking assets, people and goods; assisting navigation systems; and mapping. Indoor Positioning Systems (IPSs) are used where satellite and other outdoor positioning technologies lack precision or fail. Ultra-WideBand (UWB) technology is especially suitable for an IPS, as it operates under high data transfer rates over short distances and at low power densities, although signals tend to be disrupted by various objects. This paper presents a comprehensive study of the precision, failure, and accuracy of 2D IPSs based on UWB technology and a pseudo-range multilateration algorithm using Time Difference of Arrival (TDoA) signals. As a case study, the positioning of a 4×4m2 area, four anchors (transceivers), and one tag (receiver) are considered using bitcraze’s Loco Positioning System. A Cramér–Rao Lower Bound analysis identifies the convex hull of the anchors as the region with highest precision, taking into account the anisotropic radiation pattern of the anchors’ antennas as opposed to ideal signal distributions, while bifurcation envelopes containing the anchors are defined to bound the regions in which the IPS is predicted to fail. This allows the formulation of a so-called flyable area, defined as the intersection between the convex hull and the region outside the bifurcation envelopes. Finally, the static bias is measured after applying a built-in Extended Kalman Filter (EKF) and mapped using a Radial Basis Function Network (RBFN). A debiasing filter is then developed to improve the accuracy. Findings and developments are experimentally validated, with the IPS observed to fail near the anchors, precision around ±3cm, and accuracy improved by about 15cm for static and 5cm for dynamic measurements, on average
On the energy consumption and ranging accuracy of ultra-wideband physical interfaces
Ultra-wideband (UWB) communication is attracting increased interest for its high-accuracy distance measurements. However, the typical current consumption of tens to hundreds of mA during transmission and reception might make the technology prohibitive to battery-powered devices in the Internet of Things. The IEEE 802.15.4 standard specifies two UWB physical layer interfaces (PHYs), with low- and high-rate pulse repetition (LRP and HRP, respectively). While the LRP PHY allows a more energy-efficient implementation of the UWB transceiver than its HRP counterpart, the question is whether some ranging quality is lost in exchange. We evaluate the trade-off between power and energy consumption, on the one hand, and distance measurement accuracy and precision, on the other hand, using UWB devices developed by Decawave (HRP) and 3db Access (LRP). We find that the distance measurement errors of 3db Access devices have at most 12 cm higher bias and standard deviation in line-of-sight propagation and 2-3 times higher spread in non-line-of-sight scenarios than those of Decawave devices. However, 3db Access chips consume 10 times less power and 125 times less energy per distance measurement than Decawave ones. Since the LRP PHY has an ultra-low energy consumption, it should be preferred over the HRP PHY when energy efficiency is critical, with a small penalty in the ranging performance.acceptedVersionPeer reviewe
Bidirectional UWB Localization: A Review on an Elastic Positioning Scheme for GNSS-deprived Zones
A bidirectional Ultra-Wideband (UWB) localization scheme is one of the three
widely deployed design integration processes ordinarily destined for time-based
UWB positioning systems. The key property of the bidirectional UWB localization
is its ability to serve both the navigation and tracking assignments on-demand
within a single localization scheme. Conventionally, the perspective of
navigation and tracking in wireless localization systems is viewed distinctly
as an individual system because different methodologies were required for the
implementation process. The ability to flexibly or elastically combine two
unique positioning perspectives (i.e., navigation and tracking) within a single
scheme is a paradigm shift in the way location-based services are observed.
Thus, this article addresses and pinpoints the potential of a bidirectional UWB
localization scheme. Regarding this, the complete system model of the
bidirectional UWB localization scheme was comprehensively described based on
modular processes in this article. The demonstrative evaluation results based
on two system integration processes as well as a SWOT (strengths, weaknesses,
opportunities, and threats) analysis of the scheme were also discussed.
Moreover, we argued that the presented bidirectional scheme can also be used as
a prospective topology for the realization of precise location estimation
processes in 5G/6G wireless mobile networks, as well as Wi-Fi fine-time
measurement-based positioning systems in this article.Comment: 30 pages, 12 figure
Medição de distância relativa utilizando tecnologia UWB
TCC (graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia Elétrica.Neste documento será proposta uma implementação de um sistema para medir distâncias relativas entre dispositivos dentro de uma rede. A tecnologia utilizada para a realização do trabalho foi ultra banda larga, e será apresentado e descrito neste documento as principais caracterÃsticas desta tecnologia, os algoritmos utilizados para realizar o cálculo de distâncias, o protocolo de comunicação implementado e algumas funções adicionais. Ao final são apresentados os resultados obtidos juntamente com uma análise, é mostrada a diferença entre os resultados obtidos com a utilização de dois algoritmos distintos e são também propostos trabalhos futuros relacionados ao projeto.In this document we propose an implementation of a system to measure relative distances between devices inside a network. The technology used will be ultra-wideband (UWB), and in this document we present the main characteristics of this technology, the algorithms used to calculate de distances, the communication protocol implemented and a few additional functionalities. In the end the results will be presented together with a analysis, and the difference between two different algorithms is shown, as well as related future work