A new method for wireless synchronization and TDOA error reduction in UWB positioning system

Djaja-Jośko, Vitomir; Kołakowski, Jerzy

doi:10.1109/mikon.2016.7492077

Cited by 28 publications

(15 citation statements)

References 3 publications

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“…To compensate for clock drift errors in the anchor nodes [10], [19], the receiving times of all anchors will be translated to the time reference of the anchor 0 node. This anchor 0 node will periodically send an UWB pulse.…”

Section: B Wireless Clock Synchronizationmentioning

confidence: 99%

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Anchor Pair Selection for Error Correction in Time Difference of Arrival (TDoA) Ultra Wideband (UWB) Positioning Systems

Herbruggen

Fontaine

Poorter

2021

2021 International Conference on Indoor Positioning and Indoor Navigation (IPIN)

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Ultra wideband positioning systems typically use techniques such as two way ranging (TWR) or time difference of arrival (TDoA) to calculate the position of mobile tags. TDoA techniques require the transmission of only a single packet by the mobile tag, thus providing better scalability, higher update rates and less energy consumption than TWR techniques. However, the TDoA performance degrades heavily when a subset of the anchors are in non-line-of-sight (NLOS) conditions with the tag or with each other. To remedy this, we propose and compare different algorithms to select a subset of anchor pairs before calculating the TDoA position in 3 different conditions: LOS conditions between all devices, NLOS conditions between tag and anchor nodes and NLOS conditions between anchors and between tag and anchor nodes. We use an experimental setup with 1 tag and 8 anchor nodes to compare the accuracy gains obtained by using both simple algorithms and more complex machine learning (ML) based algorithms applied on the channel impulse responses of anchor pairs. By selecting the best anchor combinations our algorithms can reduce the positioning error by 75% (assuming perfectly known ground truth), by 19% using realistically low complexity algorithms and by 38% for ML based algorithms.

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Section: B Wireless Clock Synchronizationmentioning

confidence: 99%

“…This synchronization can be done wired or wireless. The authors of [10] present a TDoA positioning system with a mean error of 15-20 cm in a simple environment when the tag was placed in the middle of the room. In passive TDoA localization, only the anchor nodes are transmitting UWB pulses.…”

Section: Introductionmentioning

confidence: 99%

Anchor Pair Selection for Error Correction in Time Difference of Arrival (TDoA) Ultra Wideband (UWB) Positioning Systems

Herbruggen

Fontaine

Poorter

2021

2021 International Conference on Indoor Positioning and Indoor Navigation (IPIN)

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“…Since a 1 ns timing error translates in 30 cm inaccuracy, it is necessary to obtain sub-nanosecond synchronization. This can be achieved by means of expensive hardware such as Rubidium RbXO clocks or alternative implementations as described in [ 22 ]. A feasible solution is to use UWB to synchronize the anchors too.…”

Section: Localization Schemes and Mac Considerationsmentioning

confidence: 99%

Analysis of the Scalability of UWB Indoor Localization Solutions for High User Densities

Ridolfi

Velde

Steendam

et al. 2018

Sensors

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Radio frequency (RF) technologies are often used to track assets in indoor environments. Among others, ultra-wideband (UWB) has constantly gained interest thanks to its capability to obtain typical errors of 30 cm or lower, making it more accurate than other wireless technologies such as WiFi, which normally can predict the location with several meters accuracy. However, mainly due to technical requirements that are part of the standard, conventional medium access strategies such as clear channel assessment, are not straightforward to implement. Since most scientific papers focus on UWB accuracy improvements of a single user, it is not clear to which extend this limitation and other design choices impact the scalability of UWB indoor positioning systems. We investigated the scalability of indoor localization solutions, to prove that UWB can be used when hundreds of tags are active in the same system. This paper provides mathematical models that calculate the theoretical supported user density for multiple localization approaches, namely Time Difference of Arrival (TDoA) and Two-Way Ranging (TWR) with different MAC protocol combinations, i.e., ALOHA and TDMA. Moreover, this paper applies these formulas to a number of realistic UWB configurations to study the impact of different UWB schemes and settings. When applied to the 802.15.4a compliant Decawave DW1000 chip, the scalability dramatically degrades if the system operates with uncoordinated protocols and two-way communication schemes. In the best case scenario, UWB DW1000 chips can actively support up to 6171 tags in a single domain cell (no handover) with well-selected settings and choices, i.e., when adopting the combination of TDoA (one-way link) and TDMA. As a consequence, UWB can be used to simultaneously localize thousands of nodes in a dense network. However, we also show that the number of supported devices varies greatly depending on the MAC and PHY configuration choices.

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“…From 2000 onward, there has been an emerging trend of adopting the TDoA technique into in-door location systems [10], especially with ultrawideband (UWB) signals [11,12]. The benefit of this synchronization-free technique and low latency signal in-door location system with UWB signal and TDoA technique is the attainment of low latency and high precision in real system deployment [13][14][15][16][17]. In navigation systems like GPS, the (geometric) dilution of precision (DoP) is a measurement of location error compared with sensor data error.…”

Section: Introductionmentioning

confidence: 99%

Dilution of precision for time difference of arrival with station deployment

Zhang

Ding

et al. 2021

IET Signal Processing

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A study is conducted with the aim to reveal the relationship between the performance of moving object tracking algorithms and tracking anchor (station) deployment. The dilution of precision (DoP) for the time difference of arrival (TDoA) technique with respect to anchor deployment is studied. Linear and non-linear estimators are used for TDoA algorithms. The research findings for the linear estimator indicate that the DoP attains a lower value when other anchors are scattered around a central anchor; for the non-linear estimator, the DoP is optimal when the anchors are scattered around the target tag. Experiments on both algorithms are conducted that target location precision related to anchor deployment in practical situations for tracking moving objects integrated with a Kalman filter in an ultra-wideband (UWB)-based real-time localization system. The work provides a guideline for deploying anchors in UWB-based tracking systems.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

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A new method for wireless synchronization and TDOA error reduction in UWB positioning system

Cited by 28 publications

References 3 publications

Anchor Pair Selection for Error Correction in Time Difference of Arrival (TDoA) Ultra Wideband (UWB) Positioning Systems

Anchor Pair Selection for Error Correction in Time Difference of Arrival (TDoA) Ultra Wideband (UWB) Positioning Systems

Analysis of the Scalability of UWB Indoor Localization Solutions for High User Densities

Dilution of precision for time difference of arrival with station deployment

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