This dissertation considers gray-space primary-secondary spectrum sharing, in which secondary devices are allowed to transmit when primary transmissions are strong enough that additional interference would be tolerable, rather than when the primary transmissions are weak or absent so the spectrum is considered unused, as occurs in white-space sharing. To avoid causing harmful interference (i.e., interference causing disruptions in services), transmit power of a secondary device is dynamically adjusted. Various novel sharing mechanisms are proposed for two different types of primary system: cellular systems, and rotating radars. Both cases when primary and secondary systems cooperate (cooperative sharing), and when they do not (coexistent sharing) are considered. Based on analyses and extensive Monte Carlo simulations, this dissertation shows that useful secondary transmissions are possible even when the shared spectrum is considered 100% utilized by the primary system under conventional approaches to spectrum management. For example, in spectrum sharing with cellular systems, even when the primary system is 100% utilized, a modest extent of transmissions of around 0.01–0.03 bps/Hz is achievable for secondary transmitter and receiver that are 400 m apart. In spectrum sharing with radars, even in the scenario where radars are the most densely packed, a secondary transmitter can get almost 1.2 bps/Hz on average, when 5% of the transmitters are competing for the shared spectrum. This dissertation also shows the potential of sharing models in which a secondary system has information about a primary system, but does not cooperate in real time; such arrangements are not typically considered today. For sharing with radars, the case in which an OFDMA-based cellular system operates as the secondary spectrum-user in non-contiguous cells is considered, as might occur with a broadband hotspot service, or a cellular system using shared spectrum to supplement its dedicated spectrum. It is found that even with fluctuations and interruptions in secondary transmissions while radars rotate, the shared spectrum could be used efficiently for applications that generate much of the traffic on mobile Internet, including non-interactive video on demand, peer-to-peer file sharing, large file transfers, and web browsing, but not for applications such as real-time transfers of small files, and VoIP. For sharing with cellular systems, the efficiency of cooperative and coexistent sharing is compared based on performance of the secondary system measured as achievable transmissions, and performance of the cellular system measured as power consumption of a mobile device, which may be increased to compensate for additional interference from secondary transmissions. When both achievable secondary transmissions and primary power consumption are of concern, coexistent sharing is found to be as effective as cooperative sharing.

Thèse (M.A.) -- Université Laval, 2004. / Bibliogr.: f. [160]-170. Publié aussi en version électronique.

Uma antena-radar clássica é composta basicamente de uma fonte primária justaposta a um foco refletor parabólico. A lei de iluminação é estabelecida de maneira a satisfazer, tão precisamente quanto possível, a forma do feixe desejado. É a movimentação do conjunto que garante a cobertura de exploração desejada. O presente texto estuda o projeto e desenvolvimento de um servomecanismo capaz de suportar e posicionar uma antena de radar, dentro de parâmetros e restrições definidas. Os objetivos do trabalho são: levantar e estudar os fatores relevantes para especificação de um projeto de controle de posição de uma antena-radar através de servomecanismos; apresentar uma proposta de projeto de controle de posição através de servomecanismo; propor um modelo estrutural teórico consistente do conjunto antena-radar para fins de simulação dinâmica e análise modal da estrutura, e apresentar a implantação do sistema de controle proposto num projeto real de Engenharia, para o servomecanismo de uma antena de radar meteorológico. A proposta de controle foi aplicada com êxito no Modelo de Engenharia do Radar Meteorológico Doppler RMD700S-1M, desenvolvido pelo consórcio Omnisys/Atech, que foi instalado e opera em Mogi das Cruzes/SP. O texto apresenta, de forma estruturada, os fatores relevantes que devem ser levados em consideração para o desenvolvimento de um projeto deste tipo. Como conclusões do texto, são apresentadas considerações com relação ao projeto, apontando pontos positivos e negativos do desenvolvimento. / A classical radar antenna is basically composed of a primary source mounted at the focal point of a parabolic reflector. The illumination rule is established so that the desired beam-shape is attained, as precisely as possible. The physical motion of the set guarantees the coverage of the desired volume of exploitation. The actual text studies the design and development of a servomechanism capable of supporting and positioning a radar antenna, within well-defined parameters and restrictions. The aims of the dissertation are: determination and study of relevant factors for the specification of a control system design for the positioning of a servodriven radar antenna; presentation of a servo-driven positioning control system design proposal; proposal of a consistent theoretical structural model of the radar antenna set for the purpose of dynamic simulation and modal analysis of the structure and; presentation of the implementation of the proposed control system in a real Engineering design project: a servo-driven weather radar antenna. The control propose was successfully employed at the Engineering Model of the Doppler weather radar RMD700S-1M, developed by the trust Omnisys/Atech, installed and operant at Mogi das Cruzes/SP. The text presents, in a structured form, all relevant factor that must be taken into account in the development of such design. The conclusions drawn at the end of the dissertation are considerations regarding the design, which point out faults and weak points of the development.

O objetivo dessa tese é detectar e classificar problemas de medição de nível por princípio de radar de propagação de onda livre por meio de RNA (redes neurais artificiais) e SVM (support vector machines) aliados à tratamentos estatísticos. Um primeiro cenário com ambiente controlado foi montado para a obtenção de dados preliminares. Na sequência, outros três cenários empregaram dados industriais reais. Para tanto, algumas topologias de redes neurais em quatro cenários diferentes foram testadas e foi possível demonstrar o funcionamento eficiente da RNA com acertos de 100% para o primeiro cenário, 93,51% para o segundo, 99,75% para o terceiro e de 99,94% para o quarto cenário. Para esses mesmos quatro cenários, os resultados de classificação do SVM foram de 100%, 84,41%, 93,74% e de 96,40%. Os resultados obtidos demonstram que a técnica desenvolvida pode ser aplicada à cenários reais de medição de nível. Após a classificação dos problemas pela RNA ou SVM é recomendada a utilização de alguns dos ícones baseados na norma internacional NAMUR NE107 para reportar as diferentes classificações de problemas resultantes da aplicação das técnicas dessa tese. Propõe-se que essas técnicas sejam embarcadas em aplicativos computacionais de gerenciamento de ativos para melhorar a confiabilidade da medição, antecipar rotinas de manutenção dos instrumentos e aumentar a segurança da planta industrial através de reportes adequados aos usuários dos problemas de medição de nível e do mapeamento das fases do processo. / The aim of this Thesis is to detect and classify level measurement problems by free wave propagation radars using ANN (artificial neural network) and SVM (support vector machines) with statistical pre-processing data. In the first scenario, a controlled environment was build in order to get the preliminary data. In addition, three other scenarios with real industry data was considered. Therefore, some topologies of neural networks and SVM in four different scenarios were tested and it was demonstrated the efficiency of ANN to reach an accuracy rate of 100% for the first scenario, 93.51% for the second, 99.75% for third and 99.94% for the fourth scenario. For these same four scenarios, the results of SVM classification were 100%, 84.41%, 93.74% and 96.40%. After classifying the problems by ANN or SVM, it is recommended to use some of the icons following the international standard NAMUR NE107 to report the different classifications of problems within this thesis. It is proposed that these techniques be embedded in asset management environment to improve the reliability of level measurement, antecipate maintenance routines and improve plant safety through adequately reporting the classified problems and mapping stage of the process to the users.

No description available.

<p>This thesis concerns with the localization, tracking, and sensor management in the Multiple-Input Multiple-Output (MIMO) radar systems. The collocated and widely-separated MIMO radars are separately discussed and the signal models are derived for both structures.</p> <p>The first chapter of the thesis is dedicated to the tracking and localization in collocated MIMO radars. A novel signal model is first formulated and the localization algorithm is developed for the derived signal model to estimate the location of multiple targets falling in the same resolution cell. Furthermore, a novel tracking algorithm is proposed in which the maximum bound on the number of uniquely detectable targets in the same cell is relaxed. The performance of the tracking and localization algorithms is finally evaluated using the tracking Posterior Cramer-Rao Lower Bound (PCRLB).</p> <p>After showing the impact of the antennas position on the localization CRLB, a novel sensor management technique is developed for the collocated MIMO radars in Chapter 4. A convex optimization technique is proposed for the antenna allocation in a single-target scenario. When multiple targets fall inside the same cell, a sampling-based technique is formulated to tackle the non-convexity of the optimization problem.</p> <p>The third chapter of this thesis also proposes new approaches for detection, localization, and tracking using a widely-separated MIMO radar. A scenario with multiple-scatterer targets is considered and the detection performance of both MIMO and multistatic radars will be evaluated in the designed scenario. To estimate the location of the multiple-scatterer target, a Multiple-Hypothesis (MH) based approach is proposed where the number and the location of multiple targets are both estimated. A particle filter based approach is also formulated for the dynamic tracking by a widely-separated MIMO radar. Finally, the performance of the MIMO radar and the miultistatic radar in detecting and localizing multiple-scatterer targets is studied.</p> / Doctor of Philosophy (PhD)

Cette thèse présente l'étude de l'utilisation du signal XM comme source d'opportunité d'un système radar de détection passive cohérente. Par la réception simultanée d'un écho radar et du signal direct, une mesure de la corrélation est possible afin d'extraire de la détection les paramètres de la cible. Tout d'abord, une étude de la résolution qu'offre le signal employé et un bilan de puissance sont réalisés desquels deux principaux problèmes sont identifiés : l'effet hautement interféreur du signal direct sur un écho potentiel et la faiblesse de la puissance de cet écho provenant de la réflexion du signal sur une cible caractéristique. La méthode des sous-espaces, en utilisant une antenne-réseau à la réception, est proposée pour supprimer le signal direct par la projection dans son sous-espace orthogonal. Pour pallier le problème de la faiblesse de la puissance de l'écho, un gain directif est aussi proposé par l'utilisation d'un réseau à chevauchement d'éléments permettant d'obtenir ce gain tout en gardant une résolution nécessaire à la méthode des sous-espaces. Le choix du nombre de sous-réseaux employé est ensuite optimisé pour un gain maximal tout en évitant la présence de points nuls pour certaines valeurs de sous-réseaux engendrant la présence du signal direct malgré l'opération visant sa suppression. L'impact de l'estimation de la soustraction de la matrice de covariance du bruit est aussi étudié. Le système de détection intégré est ensuite présenté pour la détection de la cible caractéristique afin d:en vérifier l'efficacité.

Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2017-2018 / Ce mémoire présente des estimateurs d'états dans le but de pister des cibles devant un lidar dont la résolution angulaire est faible. D'abord, la transformée de Hough est adaptée à la configuration polaire du lidar et au bruit de mesure qui est gaussien en distance radiale et uniforme en position angulaire. La transformée de Hough développée permet d'estimer la trajectoire de la cible en évaluant la meilleure droite passant par les détections les plus récentes et cette estimation s'approche du maximum de vraisemblance. Ensuite, le résultat de la transformée de Hough est intégré à un filtre de Kalman, classique, étendu ou non parfumé. Deux stratégies sont employées : transformer le bruit uniforme en bruit gaussien en projetant les mesures de position angulaire sur la droite ou ajouter la droite comme une contrainte relaxée dans les observations du filtre de Kalman. Des simulations montrent que le filtre de Kalman non parfumé avec contrainte relaxée est celui qui offre les meilleures performances d'estimation en moyenne. Particulièrement, le gain de l'utilisation de cette méthode par rapport au filtre non parfumé ordinaire augmente dans les situations suivantes : lorsque la cible s'éloigne, plus elle est loin du lidar, plus la cible est petite par rapport à la largeur d'un élément lidar. Les simulations sont analysées pour difiérentes trajectoires linéaires et courbes, pour des cibles de deux tailles (piéton ou voiture) et trois configurations lidars (16 éléments de 2:8° chaque, 8 éléments de 5° chaque et 9 éléments de 10° chaque). Des résultats expérimentaux pour des piétons et une configuration de 16 éléments sont aussi illustrés. / In this master's thesis, state estimators are designed to track targets seen by a lidar with very low angular resolution. The Hough transform is modified in order to consider the polar configuration of the lidar detections, the gaussian noise on their distance measurements and the uniform noise on their angular position measurements. The designed Hough transform estimates the trajectory of a target by evaluating the best line passing on the most recent detections. This estimation approaches the maximum likelihood. Some methods to reduce the computational complexity are also shown. The results of the Hough transform are then combined with Kalman filters (classic, extended and unscented). Two main strategies are developed : transforming the uniform noise into gaussian noise by projecting the angular position on the estimated line, or adding the line as soft constraints in the observation vector of the Kalman filter. Simulations show that the unscented Kalman filter with soft constraints has the lowest mean square error on the state estimation on average. Moreover, this method's improvement in accuracy, in comparaison to a regular unscented Kalman filter, is significant in the following cases : when the target moves away, when the target is far away or when the target is smaller than the width of a lidar element. Simulations are done for different linear and curved trajectories, for two sizes of targets (pedestrian and car) and for three lidar configurations (16 elements of 2:8° each, 8 elements of 5° each et 9 elements of 10° each). Experimental results for pedestrians and a 16 elements lidar are also discussed.

Par le principe du temps vol, un système émettant un pulse peut mesurer à quelle distance se trouve des cibles en calculant les délais d'arrivée des échos retournés par les obstacles. Des situations de détection complexes doivent être résolues, telles que deux cibles dont les échos se superposent partiellement. L'algorithme de détection développé a donc pour objectif de distinguer des cibles rapprochées entre elles, de façon fiable et précise, avec une bonne immunité au bruit, sur des signaux exclusivement réels, où seule l'information sur l'amplitude de l'enveloppe du signal est disponible. L'algorithme développé sera basé sur l'algorithme MUSIC. Ce dernier est inutilisable tel quel, dû à la nature des signaux. Une adaptation est tout d'abord élaborée, puis optimisée. Cette version de l'algorithme surpasse les performances des algorithmes de notre partenaire industriel et des méthodes de détection généralement employées et est en mesure de distinguer les échos de cibles rapprochées entre elles. / By using the time-of-flight principle, a system emitting a pulse is able to measure the distance of a target by calculating the echoes' delays returned by the obstacles. Some complex detection situations must be solved, such as two targets producing overlapping echoes. The goal of the detection algorithm is to distinguish targets with overlapping echoes, with a good precision and a good immunity to noise, using real signals, which only the enveloppe's amplitude information is available. The created algorithm is based on the MUSIC algorithm. The later is not working as it is, because of the signals' properties. An adaptation is created, and then optimized. The most substantial improvement comes from the decorrelation processing applied on the signals' covariance matrix. The effect is a decorrelation of the sources, allowing the algorithm to distinguish targets with overlapping echoes. Also, most of the decorrelation techniques help to detect echoes with low SNRs. Another improvement concerns the measurement resolution, which is better than just the sample period. The algorithm's performances exceed those of our industrial partner algorithms and those of commonly used detection methods. The ultimate goal of the project is to integrate the developped algorithm into our industrial partner's system. It has to be real time application, and to respect the cost and ressources constaints of the system. Consequently, some optimizations of the algorithm were required. Some specific properties of the covariance matrix allowed a decrease of the memory space to save its data. This way, the number of matrix's data saved represents less than 5% of the initial covariance matrix. Another optimization is done by using an iterative method for the eigenvalue decomposition, accelerating significantly the processing time. Finally, the algorithm 'sperformances coming out of the comparative tests completed between the adapted MUSIC algorithm and our industrial partner's algorithms demonstrate that the project's goals are fullfilled. The developped algorithm can solve the situation where two targets produce overlapping echoes, while providing a good noise immunity.

L'un des enjeux dans la compréhension des relations Soleil-Terre est l'étude de la dynamique des régions internes de la magnétosphère. Dans ce contexte, l'objectif de mon travail a été de poser les bases d'un modèle opérationnel de détection et de suivi des régions frontières de la magnétosphère à partir du réseau de radars SuperDARN, qui sonde l'ionosphère à haute latitude. L'élaboration d'un tel modèle requiert une réduction de données. Pour cela, une méthode de décomposition en valeurs singulières (SVD) a été appliquée sur la mesure brute (une fonction d'autocorrélation) afin de définir trois nouveaux paramètres statistiques. L'interprétation de ces trois nouveaux paramètres montre que cette approche, bien qu'empirique, offre une description bien plus complète des échos radar que les modèles physiques habituellement utilisés. L'utilisation de ces paramètres avec une méthode de décision Bayésienne permet d'améliorer la détection de la frontière des lignes de champ géomagnétiques ouvertes/fermées. L'introduction d'un formalisme Bayésien comporte plusieurs avantages : il permet de valider le résultat en estimant une erreur sur la localisation, et de plus, il facilite l'introduction de nouvelles connaissances provenant de différents instruments. Ceci est loin d'être négligeable pour compléter les observations des radars SuperDARN. Par ailleurs, les propriétés de ce nouveau modèle ont permis l'élaboration d'un nouvel algorithme de prétraitement et d'analyse des mesures brutes.