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Titre : GNSS/5G Hybridization for Urban Navigation Type de document : Thèse/HDR Auteurs : Anne-Marie Tobie, Auteur ; Axel Javier Garcia Pena, Directeur de thèse ; Paul Thevenon, Directeur de thèse Editeur : Toulouse : Université Fédérale Toulouse Midi-Pyrénées Année de publication : 2021 Importance : 287 p. Format : 21 x 30 cm Note générale : Bibliographie
Thèse pour obtenir le doctorat de l'Université de Toulouse, Spécialité Informatique et TélécommunicationsLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] 4G
[Termes IGN] 5G
[Termes IGN] bruit blanc
[Termes IGN] GNSS assisté pour la navigation
[Termes IGN] milieu urbain
[Termes IGN] modèle mathématique
[Termes IGN] positionnement en intérieur
[Termes IGN] positionnement par GNSS
[Termes IGN] signal Galileo
[Termes IGN] signal GPS
[Termes IGN] simulation de signal
[Termes IGN] temps de propagation
[Termes IGN] trajet multipleIndex. décimale : THESE Thèses et HDR Résumé : (Auteur) Over the past few years, the need for positioning, and thus the number of positioning services in general, has been in constant growth. This need for positioning has been increasingly focused on constrained environments, such as urban or indoor environments, where GNSS (Global Navigation Satellite System) is known to have significant limitations: multipath as well as the lack of Line-of-Sight (LOS) satellite visibility degrades the GNSS positioning solution and makes it unsuitable for some urban or indoor applications. In order to improve the GNSS positioning performance in constrained environments, many solutions are already available: hybridization with additional sensors, [1], [2] or the use of signals of opportunity (SoO) for example, [3], [4], [5], [6], [7], [8]. Concerning SoO, mobile communication signals, such as the 4G Long Term Evolution (LTE) or 5G, are naturally envisioned for positioning, [3], [9], [10]. Indeed, a significant number of users are expected to be “connected-users” and 5G systems offers promising opportunities. 5G technology is being standardized at 3GPP [11]; the first complete release of 5G specifications, Release-15, was provided to the community in March 2018. 5G is an emerging technology and its positioning performance, as well as a potential generic receiver scheme to conduct positioning operations, is still under analysis. In order to study the potential capabilities provided by 5G systems and to develop a 5G-based generic positioning module scheme, the first fundamental step is to develop mathematical models of the processed 5G signals at each stage of the receiver for realistic propagation channel models: the mathematical expression of the useful received 5G signal as well as the AWG (Additive White Gaussian) noise statistics. In the Ph.D., the focus is given to the correlation operation which is the basic function implemented by typical ranging modules for 4G LTE signals [12], DVB signals [7], [8], and GNSS [13]. In fact, the knowledge of the correlation output mathematical model could allow for the development of optimal 5G signal processing techniques for ranging positioning. Previous efforts were made to provide mathematical models of received signals at the different receiver signal processing stages for signals with similar structures to 5G signals – Orthogonal Frequency Division Multiplexing (OFDM) signals as defined in 3GPP standard, [14]. OFDM signal-type correlator output mathematical model and acquisition techniques were derived in [7], [15]. Moreover, in [8], [15], tracking techniques were proposed, analyzed and tested based on the correlator output mathematical model of [7]. However, these models were derived by assuming a constant propagation channel over the duration of the correlation. Unfortunately, when the Channel Impulse Response (CIR) provided by a realistic propagation channel is not considered to be constant over the duration of the correlation, the correlator output mathematical models are slightly different from the mathematical models proposed in [7], [8]. Therefore, the first main point considered in the Ph.D. consists in the development of mathematical models and statistics of processed 5G signals for positioning. In order to derive accurate mathematical models, the time evolution impact of the 5G standard compliant propagation channel is of the utmost importance. Note that, in the Ph.D., the continuous CIR will be approximated by a discretized CIR, and the continuous time-evolution will be replaced by the propagation channel generation sampling rate notion. This approximation makes sense since, in a real transmission/reception chain, the received time-continuous signal is, at the output of the Radio-Frequency (RF) front-end, sampled. Therefore, a preliminary step, prior to derive accurate mathematical models of processed 5G signals, consists in determining the most suitable CIR-generation sampling interval for a selected 5G standard compliant propagation channel, QuaDRiGa: trade-off between having a realistic characterization and its complexity. Complexity is especially important for 5G compliant channels with multiple emitter and receiver antennas, and high number of multipath. Then, the impact of a time-evolving propagation channel inside an OFDM symbol duration is studied. A method to select the most appropriate CIR sampling interval for accurate modelling of symbol demodulation, correlator outputs and delay tracking will also be proposed. Based on the correlator output mathematical models developed for realistic multipath environments for both GNSS and 5G systems, ranging modules are then developed. These ranging modules outputs the pseudo ranging measurements required to develop navigation solution. In order to improve the positioning availability and GNSS positioning performance in urban environment through the exploitation of 5G signals, both systems, GNSS and 5G communication systems, must be optimally combined. In fact, in order to achieve this optimal combination, both types of signals must be optimally processed, and the mathematical model of their generated pseudo range measurements must be accurately characterized. The second main objective of the Ph.D. aims thus at realistically characterizing GNSS and 5G pseudo range measurement mathematical models and at developing hybrid navigation modules exploiting/adapted to the derived pseudo range measurements mathematical models. In order to validate, the mathematical models developed in the Ph.D., a simulator is designed. The pseudo range measurements mathematical models are derived from a realistic simulator which integrates a typical GNSS receiver processing module and a typical 5G signal processing module proposition; moreover, in order to achieve a realistic characterization, the simulator implements highly realistic propagation channels for GNSS, SCHUN [16], and for 5G, QuaDRiGa [17] is developed. The hybrid navigation modules to be implemented and compared in this work are an Extended Kalman Filter (EKF) and an Unscented Kalman Filter (UKF). The performances of these hybrid navigation modules are then studied to quantify the improvements bringing by 5G TOA measurements. Note de contenu : 1- Introduction
2- GNSS signals, measurement model and positioning
3- 5G systems
4- Mathematical models and statistics of processed 5G signals for ranging based positioning for a realistic propagation channel
5- Synchronization module of a 5G signal
6- Characterization of pseudo range measurement errors due to propagation channels
7- Positioning in urban environment using 5G and GNSS measurements
8- ConclusionNuméro de notice : 26526 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT/URBANISME Nature : Thèse française Note de thèse : Thèse de Doctorat : Informatique et Télécommunications : Toulouse : 2021 Organisme de stage : Laboratoire de recherche ENAC nature-HAL : Thèse Date de publication en ligne : 09/04/2021 En ligne : https://hal.science/tel-03189527/ Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97534 GPS + Galileo + QZSS + BDS tightly combined single-epoch single-frequency RTK positioning / Shaolin Zhu in Survey review, vol 53 n°376 (January 2021)
[article]
Titre : GPS + Galileo + QZSS + BDS tightly combined single-epoch single-frequency RTK positioning Type de document : Article/Communication Auteurs : Shaolin Zhu, Auteur ; Dongjie Yue, Auteur ; Jian Chen, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 16 - 26 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] données BeiDou
[Termes IGN] données Galileo
[Termes IGN] données GPS
[Termes IGN] modèle stochastique
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] positionnement par GNSS
[Termes IGN] précision du positionnement
[Termes IGN] qualité du signal
[Termes IGN] Quasi-Zenith Satellite System
[Termes IGN] récepteur monofréquence
[Termes IGN] résolution d'ambiguïtéRésumé : (auteur) The multi-GNSS fusion makes positioning more reliable and accurate. Considering the signal difference of different systems, GPS + Galileo + QZSS + BDS tightly combined double-difference model (TCDDM), including function and stochastic model, is proposed. The proposed model fully utilizes the overlapping frequency signals of various systems, and thus to enhance positioning model when DISBs are known beforehand. The observations of 3 ultra-short (1~10 m) and 3 short (4~10 km) baselines were processed by self-programming software, and the single-epoch single-frequency RTK performance using different system-combined models was evaluated by ambiguity-fixed correctness rate (ACR) and positioning accuracy. It demonstrated that three- and four-system TCDDM were superior to their corresponding loosely combined double-difference model (LCDDM) for ACR and positioning accuracy especially at high cut-off elevation. Moreover, four-system TCDDM had the best RTK performance obtaining average ACRs of 100% and 97.6% even at 25° cut-off elevation for ultra-short and short baseline, respectively. Numéro de notice : A2021-047 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2019.1681681 Date de publication en ligne : 13/11/2019 En ligne : https://doi.org/10.1080/00396265.2019.1681681 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96782
in Survey review > vol 53 n°376 (January 2021) . - pp 16 - 26[article]Height system unification and estimation of the lithospheric structure beneath Vietnam through high-resolution gravity field and quasigeoid modeling / Dinh Toan Vu (2021)
Titre : Height system unification and estimation of the lithospheric structure beneath Vietnam through high-resolution gravity field and quasigeoid modeling Titre original : Unification du système de hauteur et estimation de la structure lithosphérique sous le Vietnam utilisant la modélisation du champ de gravité et du quasigéoïde à haute résolution Type de document : Thèse/HDR Auteurs : Dinh Toan Vu, Auteur ; Sylvain Bonvalot, Directeur de thèse ; Sean L. Bruinsma, Directeur de thèse Editeur : Toulouse : Université de Toulouse Année de publication : 2021 Importance : 234 p. Format : 21 x 30 cm Note générale : bibliographie
Thèse en vue de l'obtention du Doctorat de l'Université de Toulouse délivrée par l'Université Toulouse 3 - Paul SabatierLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] anomalie de pesanteur
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] données GNSS
[Termes IGN] données GOCE
[Termes IGN] géoïde gravimétrique
[Termes IGN] géoïde local
[Termes IGN] lithosphère
[Termes IGN] modèle de géopotentiel local
[Termes IGN] nivellement
[Termes IGN] quasi-géoïde
[Termes IGN] Viet NamIndex. décimale : THESE Thèses et HDR Résumé : (auteur) The goal of this work was twofold. The first part was devoted to the research of the size and physical shape of the Earth in Vietnam through the determination of a local gravimetric quasigeoid model. The second part was to better constrain the Earth's interior structure beneath Vietnam by determining the Moho and Lithosphere-Asthenosphere Boundary (LAB) depth models. For the first objective, a high-resolution gravimetric quasigeoid model for Vietnam and its surrounding areas was determined based on new land gravity data in combination with fill-in data where no gravity data existed. The resulting quasigeoid model was evaluated using 812 GNSS/levelling points in the study region. This comparison indicates that the quasigeoid model has a standard deviation of 9.7 cm and 50 cm in mean bias. This new local quasigeoid model for Vietnam represents a significant improvement over the global models EIGEN-6C4 and EGM2008, which have standard deviations of 19.2 and 29.1 cm, respectively, when compared to the GNSS/levelling data. An essential societal and engineering application of the gravimetric quasigeoid is in GNSS levelling, and a vertical offset model for Vietnam and its surrounding areas was determined based on the GNSS/levelling points and gravimetric-only quasigeoid model for this purpose. The offset model was evaluated using cross-validation technique by comparing with GNSS/levelling data. Results indicate that the offset model has a standard deviation of 5.9 cm in the absolute sense. Thanks to this offset model, GNSS levelling can be carried out over most of Vietnam's territory complying to third-order levelling requirements, while the accuracy requirements for fourth-order levelling networks is met for the entire country. To unify the height system towards the International Height Reference Frame (IHRF), the zero-height geopotential value for the Vietnam Local Vertical Datum W_0^LVD was determined based on two approaches: 1) Using high-quality GNSS/levelling data and the estimated gravimetric quasigeoid model, 2) Using the Geodetic Boundary Value Problem (GBVP) approach based on the GOCE global gravity field model enhanced with terrestrial gravity data. This geopotential value can be used to connect the height system of Vietnam with the neighboring countries. Moreover, the GBVP approach was also used for direct determination of the gravity potential on the surface at three GNSS Continuously Operating Reference Station (CORS) stations at epoch 2018.0 in Vietnam. Based on time series of the vertical component derived from these GNSS observations as well as InSAR data, temporal variations in the geopotential were also estimated on these permanent GNSS stations. This enables monitoring of the vertical datum and detect possible deformation. These stations may thus contribute to increase the density of reference points in the IHRF for this region. For the second objective, the local quasigeoid model was first converted to the geoid. Then, high-resolution Moho and LAB depth models were determined beneath Vietnam based on the local isostatic hypothesis using the geoid height derived from the estimated geoid, elevation data and thermal analysis. From new land gravity data, a complete grid and map of gravity anomalies i.e., Free-air, Bouguer and Isostatic was determined for the whole of Vietnam. The Moho depth was also computed based on the gravity inversion using the Bouguer gravity anomaly grid. All new models are computed at 1' resolution. The resulting Moho and LAB depth models were evaluated using available seismic data as well as global and local lithospheric models available in the study region. [...] Note de contenu : 1- Introduction
2- Theoretical basis
3- Data and map of gravity anomalies
4- The gravimetric quasigeoid solution
5- Quasigeoïd application for GNSS levelling and height system unification
6- Quasigeoid application for determination of the lithospheric structure
7- Conclusion and perspectivesNuméro de notice : 28495 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse française Note de thèse : Thèse de Doctorat : Sciences de la Terre et des Planètes Solides : Toulouse : 2021 Organisme de stage : Geosciences Environnement Toulouse GET DOI : sans En ligne : http://www.theses.fr/2021TOU30050 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99240 High accuracy terrestrial positioning based on time delay and carrier phase using wideband radio signals / Han Dun (2021)
Titre : High accuracy terrestrial positioning based on time delay and carrier phase using wideband radio signals Type de document : Thèse/HDR Auteurs : Han Dun, Auteur Editeur : Delft [Pays-Bas] : Delft University of Technology Année de publication : 2021 Format : 21 x 30 cm ISBN/ISSN/EAN : 978-94-6384-258-7 Note générale : bibliographie
Thèse présentée en vue de l'obtention du Doctorat de l'Université de DelftLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] centre de phase
[Termes IGN] correction du trajet multiple
[Termes IGN] interruption du signal
[Termes IGN] méthode du maximum de vraisemblance (estimation)
[Termes IGN] phase
[Termes IGN] précision du positionnement
[Termes IGN] signal GNSS
[Termes IGN] zone urbaineIndex. décimale : THESE Thèses et HDR Résumé : (auteur) Accurate position solutions are in high demand for many emerging applications. Global navigation satellite systems (GNSS), however, may not meet the required positioning performance, especially in urban environments, due to multipath and weak received power of the GNSS signal that can be easily blocked by surrounding objects. To achieve a high ranging precision and improve resolvability of unwanted reflections in urban areas, a large signal bandwidth is required. In this thesis, a terrestrial positioning system using a wideband radio signal is developed as a complement to the existing GNSS, which can provide a better ranging accuracy and higher received signal power, compared to GNSS. In the terrestrial positioning system presented in this thesis, a wideband ranging signal is implemented by means of a multiband orthogonal frequency division multiplexing (OFDM) signal. All transmitters are synchronized by time and frequency reference signals, which are optically distributed through the white-rabbit precision time protocol (WR-PTP). Like in GNSS, the to-be-positioned receiver is not synchronized to the transmitters. Positioning takes place through range measurements between a number of transmitters and the receiver. Time delay and carrier phase are to be estimated from the received radio signal, which propagated through a multipath channel. This estimation is done on the basis of the channel frequency response and using the maximum likelihood principle. To determine whether or not reflections need to be considered in the estimation model, a measure of dependence is introduced to evaluate the change of the precision (i.e., variance), and the measure of bias is introduced to assess the bias of the estimator when the reflection is not considered. Also, a methodology is proposed for sparsity-promoting ranging signal design in this thesis. Based on a multiband OFDM signal, ranging signal design comes to sparsely select as few signal bands as possible. Using fewer signal bands for ranging leads to less computational complexity in time delay and carrier phase estimation, while the ranging performance can still benefit from a large virtual signal bandwidth, which is defined by the entire bandwidth between the two signal bands at the spectral edges. It is proposed to use the Cramér-Rao lower bound (CRLB) of time delay estimation, the measure of dependence, and the measure of bias as constraints in ranging performance, and formulate an optimization problem to design a sparse multiband signal. Note de contenu : 1- Introduction
2- Multiband OFDM signal model
3- Time delay estimation
4- Carrier phase estimation
5- Signal design for positioning
6- Positioning models
7- Experimental results
8- Conclusions and recommendationsNuméro de notice : 28694 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : Thèse de Doctorat : Mathematical Geodesy and Positioning : Delft : 2021 DOI : 10.4233/uuid:98a7f072-7423-4a23-ac9b-8b88540c260d En ligne : https://doi.org/10.4233/uuid:98a7f072-7423-4a23-ac9b-8b88540c260d Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100361 A hybrid approach for recovering high-resolution temporal gravity fields from satellite laser ranging / Anno Löcher in Journal of geodesy, vol 95 n° 1 (January 2021)
[article]
Titre : A hybrid approach for recovering high-resolution temporal gravity fields from satellite laser ranging Type de document : Article/Communication Auteurs : Anno Löcher, Auteur ; Jürgen Kusche, Auteur Année de publication : 2021 Article en page(s) : n° 6 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] changement temporel
[Termes IGN] données GRACE
[Termes IGN] données TLS (télémétrie)
[Termes IGN] facteur d'échelle
[Termes IGN] fonction orthogonale
[Termes IGN] harmonique sphérique
[Termes IGN] modélisation
[Termes IGN] série temporelleRésumé : (auteur) A new approach to recover time-variable gravity fields from satellite laser ranging (SLR) is presented. It takes up the concept of lumped coefficients by representing the temporal changes of the Earth’s gravity field by spatial patterns via combinations of spherical harmonics. These patterns are derived from the GRACE mission by decomposing the series of monthly gravity field solutions into empirical orthogonal functions (EOFs). The basic idea of the approach is then to use the leading EOFs as base functions in the gravity field modelling and to adjust the respective scaling factors straightforward within the dynamic orbit computation; only for the lowest degrees, the spherical harmonic coefficients are estimated separately. As a result, the estimated gravity fields have formally the same spatial resolution as GRACE. It is shown that, within the GRACE time frame, both the secular and the seasonal signals in the GRACE time series are reproduced with high accuracy. In the period prior to GRACE, the SLR solutions are in good agreement with other techniques and models and confirm, for instance, that the Greenland ice sheet was stable until the late 1990s. Further validation is done with the first monthly fields from GRACE Follow-On, showing a similar agreement as with GRACE itself. Significant differences to the reference data only emerge occasionally when zooming into smaller river basins with strong interannual mass variations. In such cases, the approach reaches its limits which are set by the low spectral sensitivity of the SLR satellites and the strong constraints exerted by the EOFs. The benefit achieved by the enhanced spatial resolution has to be seen, therefore, primarily in the proper capturing of the mass signal in medium or large areas rather than in the opportunity to focus on isolated spatial details. Numéro de notice : A2021-026 Affiliation des auteurs : non IGN Thématique : MATHEMATIQUE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01460-x Date de publication en ligne : 23/12/2020 En ligne : https://doi.org/10.1007/s00190-020-01460-x Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96710
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