Descripteur
Documents disponibles dans cette catégorie (4306)
Ajouter le résultat dans votre panier
Visionner les documents numériques
Affiner la recherche Interroger des sources externes
Etendre la recherche sur niveau(x) vers le bas
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 Hidden Markov map matching based on trajectory segmentation with heading homogeneity / Ge Cui in Geoinformatica, vol 25 n° 1 (January 2021)
[article]
Titre : Hidden Markov map matching based on trajectory segmentation with heading homogeneity Type de document : Article/Communication Auteurs : Ge Cui, Auteur ; Wentao Bian, Auteur ; Xin Wang, Auteur Année de publication : 2021 Article en page(s) : pp 179 - 206 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] appariement de cartes
[Termes IGN] appariement de données localisées
[Termes IGN] modèle de Markov caché
[Termes IGN] réseau routier
[Termes IGN] segmentation
[Termes IGN] trajectographie par GPS
[Vedettes matières IGN] GénéralisationRésumé : (Auteur) Map matching is to locate GPS trajectories onto the road networks, which is an important preprocessing step for many applications based on GPS trajectories. Currently, hidden Markov model is one of the most widely used methods for map matching. However, both effectiveness and efficiency of conventional map matching methods based on hidden Markov model will decline in the dense road network, as the number of candidate road segments enormously increases around GPS point. To overcome the deficiency, this paper proposes a segment-based hidden Markov model for map matching. The proposed method first partitions GPS trajectory into several GPS sub-trajectories based on the heading homogeneity and length constraint; next, the candidate road segment sequences are searched out for each GPS sub-trajectory; last, GPS sub-trajectories and road segment sequences are matched in hidden Markov model, and the road segment sequences with the maximum probability is identified. A case study is conducted on a real GPS trajectory dataset, and the experiment result shows that the proposed method improves the effectiveness and efficiency of the conventional HMM map matching method. Numéro de notice : A2021-094 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10707-020-00429-4 Date de publication en ligne : 02/01/2021 En ligne : https://doi.org/10.1007/s10707-020-00429-4 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96934
in Geoinformatica > vol 25 n° 1 (January 2021) . - pp 179 - 206[article]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 How do users interact with Virtual Geographic Environments? Users’ behavior evaluation in urban participatory planning / Thibaud Chassin (2021)
Titre : How do users interact with Virtual Geographic Environments? Users’ behavior evaluation in urban participatory planning Type de document : Article/Communication Auteurs : Thibaud Chassin, Auteur ; Jens Ingensand, Auteur ; Guillaume Touya , Auteur ; Sidonie Christophe , Auteur Editeur : International Cartographic Association ICA - Association cartographique internationale ACI Année de publication : 2021 Collection : Proceedings of the ICA num. 4 Projets : 3-projet - voir note / Conférence : ICC 2021, 30th ICA international cartographic conference 14/12/2021 18/12/2021 Florence Italie Note générale : bibliographie
This study was partly funded by the Computers & Geosciences Research Scholarships co-sponsored by Elsevier and the International Association for Mathematical Geosciences (IAMG). The in-house code used in this study is under MIT licence available on github: https://github.com/thibaud-c/3DperceptionUX. The VGEs are published on Zenedo, doi: 10.5281/zenodo.5137307.Langues : Anglais (eng) Descripteur : [Termes IGN] approche participative
[Termes IGN] comportement
[Termes IGN] données localisées 3D
[Termes IGN] environnement géographique virtuel
[Termes IGN] planification urbaine
[Termes IGN] utilisateur civil
[Termes IGN] visualisation 3D
[Vedettes matières IGN] GéovisualisationRésumé : (auteur) For the past twenty years, the adoption of Virtual Geographic Environments is thriving. This democratization is due to numerous new opportunities offered by this medium. However, in participatory urban planning these interactive 3D geovisualizations are still labeled as very advanced means, and are only scarcely used. The involvement of citizens in urban decision-making is indeed carefully planned ahead to limit off-topic feedback. A better comprehension of Virtual Geographic Environments, and more specifically of users’ strategic behaviors while interacting with this medium could enhance participants’ contributions. The users’ strategic behavior was assessed in this article through an experimental study. A total of 107 participants completed online tasks about the identification of 3D scenes’ footprints, the comparison of buildings’ heights, and the visibility of objects through the scenes. The interactions of the participants were recorded (i.e. pressed keys, pointing device interactions), as well as the camera positions adopted to complete specific tasks. The results show that: (1) users get more efficient throughout the study; (2) interruptions in 3D manipulation appear to highlight difficulties in interacting with the virtual environments; (3) users tend to centralize their positions within the scene, notably around their starting position; (4) the type of task strongly affects the behavior of users, limiting or broadening their explorations. The results of this experimental study are a valuable resource that can be used to improve the design of future urban planning projects involving Virtual Geographic Environments, e.g. with the creation of personalized 3D tools. Numéro de notice : C2021-047 Affiliation des auteurs : UGE-LASTIG+Ext (2020- ) Thématique : GEOMATIQUE Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.5194/ica-proc-4-19-2021 Date de publication en ligne : 03/12/2021 En ligne : https://doi.org/10.5194/ica-proc-4-19-2021 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99395 Improving smartphone-based GNSS positioning using state space augmentation techniques / Francesco Darugna (2021)
Titre : Improving smartphone-based GNSS positioning using state space augmentation techniques Type de document : Thèse/HDR Auteurs : Francesco Darugna, Auteur ; Steffen Schön, Directeur de thèse Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2021 Collection : DGK - C, ISSN 0065-5325 num. 864 Importance : 189 p. Note générale : bibliographie
Diese Arbeit ist gleichzeitig veröffentlicht in:Wissenschaftliche Arbeiten der Fachrichtung Geodäsie und Geoinformatik der Universität Hannover - ISSN 0174-1454, Nr. 368, Hannover 2021Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] antenne GNSS
[Termes IGN] étalonnage d'instrument
[Termes IGN] positionnement par GNSS
[Termes IGN] retard troposphérique zénithal
[Termes IGN] téléphone intelligentRésumé : (auteur) Low-cost receivers providing Global Navigation Satellite System (GNSS) pseudorange and carrier phase raw measurements for multiple frequencies and multiple GNSS constellations have become available on the market in the last years. This significantly has increased the number of devices equipped with the necessary sensors to perform precise GNSS positioning. GNSS pseudorange and carrier phase are used to compute user positions. While both observations are affected by different error sources, e.g. the passage through the atmosphere, only the carrier-phase has an ambiguous nature. The resolution of this ambiguity is a crucial factor to reach fast and highly precise GNSS-based positioning. Currently, several smartphones are equipped with a dual-frequency, multi-constellation receiver. The access to Android-based GNSS raw measurements has become a strong motivation to investigate the feasibility of smartphone-based high-accuracy positioning. The quality of smartphone GNSS measurements has been analyzed, suggesting that they often suffer from low signal-to-noise, inhomogeneous antenna gain and high levels of multipath. This workshows how to tackle several of the currently present obstacles and demonstrates centimeter-level positioning with a low-cost GNSS antenna and a low-cost GNSS receiver built into an off-the-shelf smartphone. Since the beginning of the research in smartphone-based positioning, the device’s GNSS antenna has been recognized as one of the main limitations. Besides Multipath (MP), the antenna radiation pattern is the main site-dependent error source of GNSS observations. An absolute antenna calibration has been performed for the dual-frequency smartphone HuaweiMate20X. Antenna Phase Center Offset (PCO), and Variations (PCV ) have been estimated to correct for the antenna impact on the L1 and L5 phase observations. Accordingly, the relevance of considering the individual PCO and PCV for the two frequencies is shown. The PCV patterns indicate absolute values up to 2 cm and 4 cm for L1 and L5, respectively. The impactof antenna corrections has been assessed in different multipath environments using a high-accuracy positioning algorithm employing an uncombined observation model and applying Ambiguity Resolution (AR). Experiments both in zero-baseline and short-baseline configurations have been performed. Instantaneous AR in the zero-baseline setup has been demonstrated, showing the potential for cm-level positioning with low-cost sensors available inside smartphones. In short-baselines configurations, no reliable AR is achieved without antenna corrections. However, after correcting for PCV, successful AR is demonstrated for a smartphone placed in a low multipath environment on the ground of a soccer field. For a rooftop open-skytest case with large multipath, AR was successful in 19 out of 35 data-sets. Overall, the antenna calibration is demonstrated being an asset for smartphone-based positioning with AR,showing cm-level 2D Root Mean Square Error (RMSE). In GNSS-based positioning, a user within a region covered by a network of reference stations can take advantage of the network-estimated augmentation parameters. Among the GNSS error sources, atmospheric delays have a strong impact on the positioning performance and the ability to resolve ambiguities. State Space Representation (SSR) atmospheric corrections, i.e. tropospheric and ionospheric delays, are commonly estimated for the approximate user position by interpolation from values calculated for the reference stations. Widely used interpolation techniques are Inverse Distance Weighted (IDW), Ordinary Kriging (OK)and Weighted Least Squares (WLS). The interpolation quality of such techniques during severe weather events and Traveling Ionospheric Disturbances (TIDs) is analyzed. To improve the interpolation performance during such events, modified WLS methods taking advantage of the physical atmospheric behavior are proposed. To support this interpolation approach, external information from Numerical Weather Models (NWM) for tropospheric interpolation and from TID modeling for ionospheric interpolation is introduced to the algorithms. The interpolation is assessed using simulated data (considering artificial and real network geometries), and real SSR parameters generated by network computation of GNSS measurements. As examples, two severe weather events in northern Europe in 2017 and one TID eventover Japan in 2019 have been analyzed. The interpolation of SSR Zenith Tropospheric Delay(ZTD) and ionospheric parameters is evaluated. Considering the reference station positions as rover locations, the modified WLS approach marks a lower RMSE in up to 80% of the cases during sharp weather fluctuations. Also, the average error can be decreased in 64% of the cases during the TID event investigated. Improvements up to factors larger than two are observed. Furthermore, specific cases are isolated, showing particular ZTD variations where significant errors (e.g. larger than 1 cm) can be reduced by up to 20% of the total amount. As a final product of the analysis, tropospheric and ionospheric messages are proposed. The messages contain the information needed to implement the suggested interpolation. Along with the need for accurate atmospheric models, the concept of consistency in the SSR corrections is crucial. A format that can transport all the SSR corrections estimated by a network is the Geo++ SSR format (SSRZ). Exploiting the features of the SSRZ format, the impact of an error in the transported ionospheric parameters is investigated. It is shown that the position estimation strongly depends on the ionospheric modeling and mismodeling can result in cm level errors, especially in the height component. Numéro de notice : 17182 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : Thesis : Geodäsie und Geoinformatik : Hanovre : 2021 En ligne : https://dgk.badw.de/fileadmin/user_upload/Files/DGK/docs/c-864.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98000 Improving traffic sign recognition results in urban areas by overcoming the impact of scale and rotation / Roholah Yazdan in ISPRS Journal of photogrammetry and remote sensing, vol 171 (January 2021)PermalinkInferencing hourly traffic volume using data-driven machine learning and graph theory / Zhiyan Yi in Computers, Environment and Urban Systems, vol 85 (January 2021)PermalinkPermalinkPermalinkPermalinkMachine learning for the distributed and dynamic management of a fleet of taxis and autonomous shuttles / Tatiana Babicheva (2021)PermalinkPermalinkPermalinkPermalinkA method of hydrographic survey technology selection based on the decision tree supervised learning / Ivana Golub Medvešek (2021)Permalink