Orientador: Luís Geraldo Pedroso Meloni / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-16T11:37:29Z (GMT). No. of bitstreams: 1 Machado_RaquelGuerreiro_M.pdf: 2133776 bytes, checksum: 9563366e87c7b63b25e8e48bf81e0658 (MD5) Previous issue date: 2010 / Resumo: Na prática, quando um sistema faz uso de altas taxas de transmissão, os símbolos transmitidos são sujeitos a interferência inter-simbólica (ISI). Além disso, se existe movimento relativo entre o transmissor e receptor, tal movimentação provoca mudança no perfil do canal ao longo do tempo. Portanto, para que seja possível a implementação de sistemas sem-fio modernos que usem múltiplas antenas de transmissão e/ou recepção, é essencial que sejam desenvolvidos métodos que lidem com tais condições. Nesse contexto, este trabalho estuda a utilização da abordagem de estimação dos coeficientes de um canal MIMO com interferência inter-simbólica e variante no tempo e detecção de símbolos de forma conjunta. Com base na modelagem da dinâmica temporal dos coeficientes do canal e dos símbolos transmitidos, um vetor de estados é definido contendo ambas informações levando a uma não-linearidade na equação de observação do sistema proposto. Uma solução analítica para o problema de filtragem não-linear é então apresentada, bem como dois algoritmos que propõem soluções sub-ótimas. Por fim, simulações numéricas comprovam a superioridade da abordagem conjunta e mostram os desempenho dos dois algoritmos propostos para a solução do problema de estimação e detecção conjuntas em sistemas MIMO submetidos a canais sem-fio seletivos em frequência e variantes no tempo / Abstract: In practice, when a system uses high data transmission rates, the transmitted symbols are subjected to inter-symbol interference (ISI). Furthermore, if there exists a relative movement between the receiver and the transmitter, the wireless channel through which data is transmitted will vary in time. Therefore, in order to implement practical wireless systems that use multiple transmit and/or receive antennas, it is essential to devise methods to correctly detect symbols transmitted under such conditions. In this context, this dissertation studies the joint channel estimation and symbol detection approach. In establishing models for the temporal dynamic of the channel coefficients and transmitted symbols, an augmented state vector is defined containing both information, which leads to a non-linear observation equation. Then, an analytic solution is presented along with two sub-optimal algorithms. Finally, numeric simulations attest the superiority of the joint approach and confirm the performance of the algorithms for both the joint channel estimation and symbol detection approach in MIMO systems subject to frequency selective and time varying wireless channels / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

Mobile Ad hoc NETworks (MANETs) aim at making communication between mobile nodes feasible without any infrastructure support. Sparse MANETs fall into the class of Delay Tolerant Networks which are intermittently connected networks and where there is no contemporaneous end-to-end path at any given time. We first, propose a new reliable transport scheme for DTNs based on the use of ACKnowledgments and random linear coding. We model the evolution of the network under our scheme using a fluid-limit approach. We optimize our scheme to obtain mean file transfer times on certain optimal parameters obtained through differential evolution approach. Secondly, we propose and study a novel and enhanced ACK to improve reliable transport for DTNs covering both unicast and multicast flows. We make use of random linear coding at relays so that packets can reach the destination faster. We obtain reliability based on the use of so-called Global Selective ACKnowledgment. We obtain significant improvement through G-SACKs and coding at relays. Finally, we tackle the problem of estimating file-spread in DTNs with direct delivery and epidemic routing. We estimate and track the degree of spread of a message in the network. We provide analytical basis to our estimation framework alongwith insights validated with simulations. We observe that the deterministic fluid model can indeed be a good predictor with a large of nodes. Moreover, we use Kalman filter and Minimum- Mean-Squared-Error (MMSE) to track the spreading process and find that Kalman filter provides more accurate results as compared to MMSE

Orientador: Jose Claudio Geromel / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-13T09:58:44Z (GMT). No. of bitstreams: 1 Korogui_RubensHideo_D.pdf: 1047054 bytes, checksum: 1a066f84d7ea84703434bdb049a62a20 (MD5) Previous issue date: 2009 / Resumo: Uma das temáticas abordadas neste trabalho é o problema de filtragem robusta em norma H2 para sistemas lineares a tempo contínuo e a tempo discreto. Consideramos que os sistemas estão sujeitos a incertezas paramétricas inicialmente do tipo politópicas e, em seguida, do tipo que admite representação linear fracionária. Calculamos limitantes inferior e superior para a norma H2 do erro de estimação, resolvendo-se problemas minimax, escrevendo-os em formato de desigualdades matriciais lineares LMI. Dessa maneira calculamos um intervalo de otimalidade que permite certificar o desempenho do filtro robusto projetado. Em seguida, aplicamos a metodologia proposta em problemas de estimação envolvendo um motor de indução trifásico e uma linha de transmissão com derivação. O presente trabalho também apresenta o que chamamos de sistema linear de comparação, cuja proposta é servir como alternativa para estudar sistemas com atraso. Utilizando a substituição de Rekasius construímos um sistema linear invariante no tempo que permite obter informações sobre a estabilidade e o cálculo de norma H8 para sistemas desta classe. Em vista da formulação através de matrizes de representação de estado é possível estender sem maiores dificuldades os resultados para o projeto de controladores via realimentação de estado e de filtros para sistemas com atraso. / Abstract: One of the themes considered in this work is the robust H2 filtering design problem for linear time invariant continuous and discrete time systems. We assume that the systems are subject to parametric uncertainty, initially of the polytopic type and later as linear fractional transformation parametric uncertainties. We calculate lower and upper bounds to the H2 squared norm of the estimation error by means of the equilibrium solution of a minimax problem, that can be formulated in a linear matrix inequality framework. Under this approach we provide an optimality gap that allows us to certify the performance of the designed robust filter. Afterwards, we apply the proposed methodology to estimation problems involving a three-phase induction motor and a transmission line with a stub. This work also considers what we call a linear comparison system, whose goal is to serve as an alternative to study time-delay systems. Using the Rekasius substitution we construct a linear time invariant system that allows us to get information about stability and H8 norm of this class of systems. Based on this approach in terms of state space matrices it is possible to extend the results to state feedback design and filtering design without any further assumptions. / Doutorado / Automação / Mestre em Engenharia Elétrica

In the Thesis we study the problem of linear filtration of Gaussian signals in finite-dimensional space. We use the Kalman-type equations for the filter to show that the filter depends continuously on the signal. Secondly, we show the same continuity property for the covariance of the error and verify existence and uniqueness of a solution to an integral equation that is satisfied by the filter even under more general assumptions. We present several examples of application of the continuity property that are based on the theory of stochastic differential equations driven by fractional Brownian motion. 1

Les réseaux mobiles Ad hoc (MANETs) visent à permettent à des noeuds mobiles de communiquer sans aucun support d'infrastructure. Les MANETs dispersés entrent dans la catégorie des réseaux tolérants aux délais (DTN), qui sont des réseaux connectés par intermittence et où il n'y a aucun chemin de bout-en-bout persistant à n'importe quel temps donné. Nous proposons, d'abord, un nouveau protocole de transport fiable pour les DTNs basé sur l'utilisation d'accusés de réception ainsi que le codage linéaire aléatoire. Nous modélisons l'évolution du réseau conformément à notre plan en utilisant l'approche fluide. Nous obtenons le temps de transfert d'un fichier en fonction de certains paramètres optimaux obtenus par l'approche d'évolution différentielle. Deuxièmement, Nous proposons ainsi et étudions un nouveau mécanisme d'ACK augmenté, pour améliorer le transport fiable pour les DTNs, pour les cas unicast et multicast. Nous nous servons du codage linéaire aléatoire aux relais pour que les paquets puissent atteindre la destination plus rapidement. Nous obtenons la fiabilité basée sur l'utilisation Global Sélective ACKnowledgement. Enfin, nous abordons le problème de l'estimation de propagation des fichiers dans les DTNs avec livraison directe et le routage épidémique. Nous estimons et suivons le degré de propagation d'un message dans le réseau. Nous fournissons la base analytique à notre cadre d'évaluation avec des aperçus validés en se basant sur des simulations. En plus, nous utilisons le filtre de Kalman et Minimum- Mean-Squared Error (MMSE) pour suivre le processus de propagation et trouvons que le filtre de Kalman fournit des résultats plus précis par rapport à MMSE / Mobile Ad hoc NETworks (MANETs) aim at making communication between mobile nodes feasible without any infrastructure support. Sparse MANETs fall into the class of Delay Tolerant Networks which are intermittently connected networks and where there is no contemporaneous end-to-end path at any given time. We first, propose a new reliable transport scheme for DTNs based on the use of ACKnowledgments and random linear coding. We model the evolution of the network under our scheme using a fluid-limit approach. We optimize our scheme to obtain mean file transfer times on certain optimal parameters obtained through differential evolution approach. Secondly, we propose and study a novel and enhanced ACK to improve reliable transport for DTNs covering both unicast and multicast flows. We make use of random linear coding at relays so that packets can reach the destination faster. We obtain reliability based on the use of so-called Global Selective ACKnowledgment. We obtain significant improvement through G-SACKs and coding at relays. Finally, we tackle the problem of estimating file-spread in DTNs with direct delivery and epidemic routing. We estimate and track the degree of spread of a message in the network. We provide analytical basis to our estimation framework alongwith insights validated with simulations. We observe that the deterministic fluid model can indeed be a good predictor with a large of nodes. Moreover, we use Kalman filter and Minimum- Mean-Squared-Error (MMSE) to track the spreading process and find that Kalman filter provides more accurate results as compared to MMSE