Orientador: Lee Luan Ling / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-08T01:26:33Z (GMT). No. of bitstreams: 1 Vieira_FlavioHenriqueTeles_D.pdf: 4214611 bytes, checksum: 755dfe9865aff1214f8e551afde7541d (MD5) Previous issue date: 2006 / Resumo: A modelagem multifractal generaliza os modelos de tráfego existentes na literatura e se mostra apropriada para descrever as características encontradas nos fluxos de tráfego das redes atuais. A presente tese investiga abordagens para alocação de banda, predição de tráfego e estimação de probabilidade de perda de bytes considerando as características multifractais de tráfego. Primeiramente, um Modelo Multifractal baseado em Wavelets (MMW) é proposto. Levando em consideração as propriedades deste modelo, são derivados o parâmetro de escala global, a função de autocorrelação e a banda efetiva para processos multifractais. A capacidade de atualização em tempo real do MMW aliada à banda efetiva proposta permite o desenvolvimento de um algoritmo de estimação adaptativa de banda efetiva. Através deste algoritmo é introduzido um esquema de provisão adaptativo de banda efetiva. Estuda-se também a alocação de banda baseada em predição de tráfego. Para este fim, propõe-se um preditor adaptativo fuzzy de tráfego, o qual é aplicado em uma nova estratégia de alocação de banda. O preditor fuzzy adaptativo proposto utiliza funções de base ortonormais baseadas nas propriedades do MMW. Com relação à probabilidade de perda para tráfego multifractal, derivase uma expressão analítica para a estimação da probabilidade de perda de bytes considerando que o tráfego obedece ao MMW. Além disso, uma caracterização mais completa do comportamento de fila é efetuada pela obtenção de limitantes para a probabilidade de perda e para a ocupação média do buffer em termos da banda efetiva do MMW. Por fim, é apresentado um esquema de controle de admissão usando o envelope efetivo proposto para o MMW oriundo do cálculo de rede estatístico, que garante que os fluxos admitidos obedeçam simultaneamente aos requisitos de perda e de retardo. As simulações realizadas evidenciam a relevância das propostas apresentadas / Abstract: Multifractal modeling generalizes the existing traffic models and is believed to be appropriate to describe the characteristics of traffic flows of modern communication networks. This thesis investigates some novel approaches for bandwidth allocation, traffic prediction and byte loss probability estimation, by considering the multifractal characteristics of the network traffic. Firstly, a Wavelet based Multifractal Model (WMM) is proposed. Taking into account the properties of this multifractal model, we derive the global scaling parameter, the autocorrelation function and the effective bandwidth for multifractal processes. The real time updating capacity of the WMM in connection with our effective bandwidth proposal allows us to develop an algorithm for adaptive effective bandwidth estimation. Then, through this algorithm, an adaptive bandwidth provisioning scheme is introduced. In this work, we also study a prediction-based bandwidth allocation case. For this end, we develop an adaptive fuzzy predictor, which is incorporated into a novel bandwidth allocation scheme. The proposed adaptive fuzzy predictor makes use of orthonormal basis functions based on the properties of the WMM. Additionally, we derive an analytical expression for the byte loss probability estimation assuming that the traffic obeys the MMW. Besides, a more complete characterization of the queuing behavior is carried out through the estimation of the bounds for the loss probability and mean queue length in buffer in terms of the WMM based effective bandwidth. Finally, an admission control scheme is presented that uses the WMM based effective envelope derived through the statistical network calculus, guaranteeing that the admitted flows simultaneously attend the loss and delay requirements. The computer simulation results confirm the relevance of the presented proposals / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

L'étude des Systèmes Contrôlés en Réseaux (SCR) repose sur l'identification des exigences de fonctionnement de l'application appelées Qualité de Contrôle (QdC) et sur l'évaluation de la Qualité de Service (QdS) offerte par le réseau. Les travaux sur les SCR se repartissent selon deux approches : la commande en réseau et la commande de réseau. Cette thèse se positionne sur la deuxième approche avec une recherche axée sur la modélisation des mécanismes d'ordonnancement implémentés dans les équipements réseau et notamment dans les commutateurs Ethernet qui sont de plus en plus utilisés dans les applications industrielles. Ce travail de recherche étudie plus particulièrement comme paramètre de QdS, les délais qui engendrent des perturbations sur le système commandé. Cette thèse propose deux modèles de classification de service reposant sur des ordonnanceurs WRR (Weighted Round Robin). La première modélisation suit une approche constructive en utilisant la théorie du calcul réseau. La seconde s'appuie sur une phase d'identification à partir de simulations numériques et de la logique floue. Dans les deux cas, le but est d'offrir une bande passante suffisante pour le trafic contraint temporellement tout en maximisant la bande passante dédiée aux autres trafics pour éviter des effets famine. L'approche calcul réseau permet de configurer le réseau hors-ligne pour répondre à des contraintes temporelles strictes du SCR. La solution basée sur la logique floue autorise une commande dynamique de l'ordonnanceur pour ajuster en ligne le réseau en fonction des variations du trafic. Elle ne peut s'appliquer qu'à des SCR ayant des contraintes de temps souples / The study of the Networked Control Systems (NCS) is based both on the identification of the application functioning requirements called Quality of Control (QoC) and on the evaluation of the Quality of Service (QoS) offered by the network. The studies on the NCS are classified according to two approaches: the control over network and the control of network. This thesis addresses the second approach and models the scheduling mechanisms implemented in the Ethernet switches that are more and more used in the industrial applications. The specific QoS parameter studied in this thesis is the delay disturbing the controlled system. This thesis proposes two models of classification of service based on WRR (Weighted Round Robin) schedulers. The first modeling follows a constructive approach by using the network calculus theory. The second is based on an identification step from numerical simulations and from the fuzzy logic. In the two cases, the purpose is both to offer enough bandwidth for the time constrained traffic and to maximize the bandwidth dedicated to the others traffics to avoid famine effects. The network calculus approach is used to configure off-line the network in respecting the NCS strict time constraints. The solution based on the fuzzy logic enables a dynamic control of the scheduler in order to tune on-line the network according to the traffic variations. This latter can be applied only to NCS with soft time constraints

Après l'augmentation des capacités physiques des réseaux sans-fil, l'amélioration du faible rendement MAC permet aujourd'hui aux utilisateurs de bénéficier de bandes passantes inédites. Cette amélioration est notamment rendue possible par la création de systèmes d'agrégation. Or si ces systèmes permettent d'améliorer la bande passante offerte, plusieurs problématiques se posent quant à leur influence sur le comportement du système en particulier en cas de forte concurrence pour l'accès au medium. L'agrégation étudiée dans ce mémoire effectue une concaténation de plusieurs paquets dans une seule trame. Cette opération permet aux paquets de partager les en-têtes. Outre la perte de signification quant à la valeur d'un paquet, la configuration des paramètres d'un tel système reste aujourd'hui obscure pour le fournisseur d'accès. Comme les intérêts du fournisseur et de ses clients peuvent diverger, il est également nécessaire de tenir compte du compromis entre leurs exigences respectives. Afin d'adresser ces problématiques, ces travaux de thèse se concentrent sur une analyse approfondie du comportement et des implications d'un système d'agrégation de paquets (avec IEEE 802.11n pour cas d'étude). L'influence de l'agrégation sur la qualité de service offerte à une application est quantifiée au travers de plusieurs milliers de simulations effectuées avec Riverbed Modeler. Des recommandations sont ensuite proposées pour la bonne configuration du système d'agrégation dans l'optique d'optimiser les délais et l'arriéré de traitement. L'accent est mis sur les performances offertes à un flux particulier en concurrence pour le medium. Ceci dans le but de clarifier l'influence de l'agrégation sur chaque client. Cette thèse développe également un modèle analytique dudit système basé sur la théorie du calcul réseau. Les limites d'un tel modèle sont démontrées et son pessimisme est déterminé à l'aide d'une analyse fine du comportement de l'agrégation 802.11n. Cette étude démontre notamment une relative inadaptation de la théorie du calcul réseau au système d'agrégation considéré. Des ajustements de la théorie sont alors proposés, en particulier vis à vis du calcul du service rendu à un flux. Afin d'aider le fournisseur d'accès dans la configuration du système d'agrégation, cette thèse propose en dernier lieu un algorithme de configuration dynamique des paramètres d'agrégation. Cet algorithme est établi à partir des recommandations instructives établies précédemment. Son originalité repose sur la désactivation de l'agrégation en fonction de l'état des stations concurrentes. Implémenté dans Riverbed Modeler, cet algorithme montre son efficacité. De nouvelles problématiques se posent quant à son implémentation réelle (distribuée, centralisée, ...). / After the increase of the capacity of wireless networks, the improvement of the low efficiency allows users to benefit from higher bandwidths. This improvement is partly due to the creation of aggregation's systems. Now, if these systems allow to improve the offered bandwidth, several problems arise about their influence on the behavior of the system. In particular, the case of strong competition for the access to the medium remains unknown. The aggregation studied in this thesis makes a concatenation of several packets in a single frame. This operation allows the packets to share headers. Besides the loss of meaning about the value of a packet, the configuration of such a system remains today obscure for the access provider. As the interests of the provider and its customers may differ, it is also necessary to consider a compromise between their respective requirements. To address these issues, this thesis focuses on a thorough analysis of the behavior and the implications of a packet aggregation system (with IEEE 802.11n as case study). The impact of aggregation on the quality of service provided to an application is quantified through thousands of simulations with Riverbed Modeler. Recommendations are then proposed for the proper setup of the aggregation system to optimize delay and backlog. This thesis focuses on the performances offered to a particular flow in competition for the medium. Its aim is to show the influence of the aggregation on each customer. This thesis also develops an analytical model of the aggregation system using the network calculus theory. The limitations of such a model are demonstrated. Its pessimism is determined using a detailed analysis of the 802.11n aggregation. This study demonstrates a particular relative inadequacy of network calculus to the aggregation system considered. Adjustments of the theory are then proposed, particularly for the calculation of the residuel service offered to a customer. To help the access provider in the configuration of the aggregation system, this thesis lastly proposes an algorithm for a dynamic configuration of the aggregation. This algorithm is established from the recommendations previously established. Its originality is based on the deactivation of the aggregation according to the state of the competing stations. Implemented in Riverbed Modeler, this algorithm shows its efficiency. Then, new problems arise about its real implementation (distributed, centralized, ...).

La recherche dans le domaine des systèmes contrôlés en réseau a considérablement évolué depuis qu'Ethernet est de plus en plus utilisé en remplacement des traditionnels réseaux locaux industriels. Si ce choix d'Ethernet se justifie par sa faculté intrinsèque à supporter toutes les communications de l'entreprise (du bureau à l'atelier), il s'accorde difficilement avec les contraintes temporelles des applications de contrôle / commande distribuées. Contrairement aux réseaux de terrain, l'indéterminisme de l'accès à la voie d'Ethernet ne permet pas de garantir le respect des contraintes temporelles strictes.<br />La contribution de cette thèse est la définition d'une approche analytique permettant de majorer les délais de communication de bout en bout dans les systèmes contrôlés en réseau lorsqu'ils reposent sur une architecture Ethernet commutée. Les travaux se sont focalisés sur l'adaptation de la théorie du calcul réseau à ce type d'environnement. Dans ce cadre, cette thèse développe la modélisation d'un commutateur IEEE 802.1D ainsi qu'une méthode de calcul des délais de bout en bout basée sur l'augmentation du volume des rafales. Plusieurs expérimentations réelles ont permis de valider l'efficacité des bornes obtenues par calcul.<br />Outre l'évaluation de performances, ces travaux s'intéressent également à la Classification de Service (IEEE 802.1D/p) et à l'optimisation de l'ordonnancement des trames sur Ethernet. Cette thèse montre enfin comment une méthode d'évaluation de performances peut être utilisée pour dimensionner et optimiser la conception d'architectures Ethernet commutées.

Cette thèse se situe dans le contexte des systèmes (min,+)-linéaires incertains, contenus dans des intervalles dont seules les bornes sont connues. Dans un premier temps, puisque les calculs exacts - somme, inf-convolution, étoile de Kleene/clôture sous-additive - sont souvent coûteux en espace mémoire et en temps de calculs, des calculs approchés sont proposés à travers des fonctions d'inclusion. Les résultats obtenus sont des intervalles particuliers appelés conteneurs. La borne supérieure d'un conteneur est l'élément le plus grand de la classe d'équivalence du système approché selon la transformée de Legendre-Fenchel. La borne inférieure représente un minorant de cette classe d'équivalence et ainsi du système exact. Les caractéristiques de convexité de ces bornes permettent d'obtenir des algorithmes de calculs de complexité linéaire et quasi-linéaire. Dans un second temps, la commande des systèmes (min,+)-linéaires incertains est étudiée. Ces incertitudes peuvent apparaître suite aux calculs effectués sur les conteneurs proposés ci-dessus, mais également lorsque des paramètres incertains ou variables sont présents lors des modélisations. Des structures de contrôles existantes (précompensateur, retour de sortie) sont appliquées à ces systèmes incertains et les problèmes suivants sont ainsi traités : problème du Window Flow Control, réduction de l'incertitude en sortie du système contrôlé par un précompensateur, calcul d'un précompensateur neutre ralentissant les entrées sans dégrader la dynamique du système seul.

Orientador: Rafael Santos Mendes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-10T17:09:25Z (GMT). No. of bitstreams: 1 Cavalcante_MabiaDaniel_D.pdf: 2715835 bytes, checksum: c50d435fedfc8844d3524aff040c39f0 (MD5) Previous issue date: 2008 / Resumo: Network Calculus (NC) é um conjunto de regras e resultados para calcular parâmetros de desempenho de redes de comunicações. As redes de comunicações são exemplos de Sistemas Dinâmicos a Eventos Discretos (DEDS), ou seja, sistemas cujas mudanças de estado são comandadas por eventos que ocorrem em instantes discretos. As restrições matemáticas de alguns DEDS podem ser descritas mais adequadamente usando a álgebra de dióides. Existe, portanto, uma relação entre NC e álgebra de dióides. No entanto, trabalhar em uma plataforma completamente baseada na álgebra de dióides é uma abordagem nova para o NC. Nesse contexto, as contribuições deste trabalho podem ser consideradas sob dois aspectos. Por um lado, no uso sistemático da álgebra de dióides e na definição de métodos, baseados nessa álgebra, para a modelagem e análise de desempenho de redes de comunicações. Por outro lado, nas análises desenvolvidas e resultados alcançados para alguns sistemas específicos. Como uma forma de ilustrar os métodos propostos, analisam-se componentes comuns a modelo~ de redes de comunicações, tais como: enlaces conservativos, reguladores de tráfegos, buffers de recepção e multiplexadores. Alguns resultados alcançados para esses sistemas são inovadores e menos conservativos do ql1e os encontrados na literatura / Abstract: Network Calculus (NC) is a set of rules and results regarding performance parameters of communication networks. Communication networks are examples of Discrete Event Dynamic Systems (DEDS), i.e., systems whose state transitions are triggered by events that occur at discrete instants. The mathematical constraints of some DEDS can be described more adequately using the dioid algebra. Therefore, there is a relationship between NC and the dioid algebra. However, working on a framework completely based on the dioid algebra is a new approach to the NC. ln this context, the contributions of this work can be considered under two aspects. On one hand, in the systematic use of the dioid algebra and the definition of methods based on this algebra to model and analyze performance of communication networks. On the other hand, in the analysis developed and results achieved for some specific systems. To illustrate the introduced methods, some systems that are commonly faund in models af communication networks were analyzed. Among them: conservative links, traffic regulators, receive buffers (or packetizers) and multiplexers. Some of the results obtained for these systems are new and less conservative than those in the literature / Doutorado / Automação / Doutor em Engenharia Elétrica

Traffic modeling in computer networks has been researched for decades. A good model should reflect the features of real-world network traffic. With a good model, synthetic traffic data can be generated for experimental studies; network performance can be analysed mathematically; service provisioning and scheduling can be designed aligning with traffic changes. An important part of traffic modeling is to capture the dependence, either the dependence among different traffic flows or the temporal dependence within the same traffic flow. Nevertheless, the power of dependence models, especially those that capture the functional dependence, has not been fully explored in the domain of computer networks. This thesis studies copula theory, a theory to describe dependence between random variables, and applies it for better performance evaluation and network resource provisioning. We apply copula to model both contemporaneous dependence between traffic flows and temporal dependence within the same flow. The dependence models are powerful and capture the functional dependence beyond the linear scope. With numerical examples, real-world experiments and simulations, we show that copula modeling can benefit many applications in computer networks, including, for example, tightening performance bounds in statistical network calculus, capturing full dependence structure in Markov Modulated Poisson Process (MMPP), MMPP parameter estimation, and predictive resource provisioning for cloud-based composite services. / Graduate / 0984 / fdong@uvic.ca

Network Calculus views a network system as a queuing framework and provides a series of mathematical functions for finding an upper bound of an end-to-end delay. It is crucial for the design of networks and applications with a hard delay guarantee, such as the emerging Time Sensitive Network. Even though several approaches in Network Calculus can be used directly to find bounds on the worst-case delay, these bounds are usually not tight, and making them tight is a hard problem due to the extremely intensive computing requirements. This problem has also been proven as NP-Hard. One newly introduced solution to tighten the delay bound is the so-called Flow Prolongation. It extends the paths of cross flows to new sink servers, which naturally increases the worst-case delay, but might at the same time decrease the delay bound. The most straightforward and the most rigorous solution to find the optimal Flow Prolongation combinations is by doing exhaustive searches. However, this approach is not scalable with the network size. Thus, a machine learning model, Graph Neural Network (GNN), has been introduced for the prediction of the optimal Flow Prolongation combinations, mitigating the scalability issue. However, early research also found out that machine learning models consistently misclassify adversarial examples. In this thesis, Fast Gradient Sign Method (FGSM) is used to benchmark how adversarial attacks will influence the delay bound achieved by the Flow Prolongation method. It is performed by slightly modifying the input network features based on their gradients. To achieve this, we first learned the usage of NetCal DNC, an Free and Open Source Software, to calculate the Pay Multiplexing Only Once (PMOO), one of the Network Calculus methods for the delay bound calculation. Then we reproduced the GNN model based on PMOO, and achieved an accuracy of 65%. Finally, the FGSM is implemented on a newly created dataset with a large number of servers and flows inside. Our results demonstrate that with at most 14% changes on the network features input, the accuracy of GNN drastically decreases to an average 9.45%, and some prominent examples are found whose delay bounds are largely loosened by the GNN Flow Prolongation prediction after the FGSM attack. / Nätverkskalkylen behandlar ett nätverkssystem som ett system av köer och tillhandahåller ett antal matematiska funktioner som används för att hitta en övre gräns för end-to-end förseningar. Det är mycket viktigt för designen av nätverk och applikationer med strikta begränsningar för förseningar, så som det framväxande Time Sensitive Network. Även om ett flertal tillvägagångssätt i nätverkskalkylen kan användas direkt för att finna gränsen för förseningar i det värsta fallet så är dessa vanligtvis inte snäva. Att göra gränserna snäva är svårt då det är ett NP-svårt problem som kräver extremt mycket beräkningar. En lösning för att strama åt förseningsgränserna som nyligen introducerats kallas Flow Prolongation. Den utökar vägarna av korsflöden till nya sink servrar, vilket naturligt ökar förseningen i värsta fallet, men kan eventuellt också sänka förseningsgränsen. Den enklaste och mest rigorösa lösningen för att hitta de optimala Flow Prolongation kombinationerna är att göra uttömmande sökningar. Detta tillvägagångssätt är dock inte skalbart för stora nätverk. Därför har en maskininlärningsmodell, ett Graph Neural Network (GNN), introducerats för att förutspå de optimala Flow Prolongation kombinationerna och samtidigt mildra problemen med skalbarhet. Dock så visar de tidiga fynden att maskininlärningsmodeller ofta felaktigt klassificerar motstridiga exempel. I detta projekt används Fast Gradient Sign Method (FGSM) för att undersöka hur motståndarattacker kan påverka förseningsgränsen som hittas med hjälp av Flow Prolongation metoden. Detta görs genom att modifiera indata-nätverksfunktionerna en aning baserat på dess gradienter. För att uppnå detta lärde vi oss först att använda NetCal DNC, en mjukvara som är gratis och Open Source, för att kunna beräkna Pay Multiplexinng Only Once (PMOO), en metod inom nätverkskalkylen för att beräkna förseningsgränser. Sedan reproducerade GNN modellen baserat på PMOO, och uppnådde en träffsäkerhet på 65%. Slutligen implementerades FGSM på ett nytt dataset med ett stort antal servrar och flöden. Våra resultat visar att förändringar på upp till 14% på indata-nätverksfunktionerna resulterar i att träffsäkerheten hos GNN minskar drastiskt till ett genomsnitt på 9.45%. Vissa exempel identifierades där förseningsgränsen utvidgas kraftfullt i GNN Flow Prolongation förutsägelsen efter FGSM attacken.

Made available in DSpace on 2014-07-29T15:08:17Z (GMT). No. of bitstreams: 1 Dissertacao_mestrado_josemar.pdf: 1807801 bytes, checksum: b47a17ed3732deb7f34a3e310ec05477 (MD5) Previous issue date: 2011-09-29 / The multifractal modeling is more appropriate in describing some features finding in traffic flows in real networks than other models. This work investigates the behavior of the traffic modeling based policing algorithms found in the literature (Leaky Bucket, Fractal Leaky Bucket, Gaussian Multifractal Leaky Bucket) regarding the buffer utilization, the efficiency for the use of buffer efficiency in describing the accumulated traffic (envelope process), packet dropping and data loss (bytes). First, we compare the envelope process of the considered policing algorithms and the proposed algorithm MAPM (Multifractal Arrival Policing Mechanism), with traffic without policing. Next, it was calculated the system loss rate for a finity buffer system with and without policing algoritm. Using the deterministic Network Calculus, it is also estimated the average queue length (backlog) and delay of bytes by applying the concept of the Min-Plus algebra that presents some differences against the conventional algebra. The proposed policing algorithm was applied to a transmission system based on OFDM (Orthogonal Frequency - Division Multiplexing) / TDMA (Time Division Multiplexing Access) system, where it was evaluated the network performance of the considered policing algorithms. Simulations were carried out with real wireless network trace (Wi-Fi) and wired network trace in order to demonstrate the efficiency of the algorithm proposed in relation to policing algorithms in the literature. The simulations shown the efficiency of the MAPM policing algorithm with traces from wired and wireless networks. We also propose the use of deterministic Network Calculus associated to multifractal envelope process to analyze the traffic behavior in terms of delay and backlog before policing algorithms application in the network. Finally we present the results of buffer utilization, link utilization, delay and backlog to a WiMAX system where the policing algorithm MAPM in general shown delay and backlog increasing in the traffic compared with anothers algorithms and low link utilization / A modelagem multifractal tem se mostrado mais apropriada para descrever algumas características encontradas nos fluxos de tráfego de redes reais que outros modelos, tais como o modelo de Poisson e Markov. Este trabalho investiga o comportamento dos algoritmos de policiamento baseados em modelagem de tráfego (Balde Furado, Balde Furado Fractal, Balde Furado Multifractal Gaussiano) em relação à utilização do buffer, eficiência em descrever o tráfego acumulado (processo envelope) e descarte de pacotes e perda de dados (bytes). Primeiramente, compara-se o processo envelope dos algoritmos de policiamento considerados e do algoritmo proposto neste trabalho, o MAPM (Multifractal Arrival Policing Mechanism), com o tráfego sem policiamento. Em seguida, a taxa de perda em um enlace simples com buffer finito com e sem algoritmo de policiamento é calculada. Utilizando o Cálculo de Rede Determinístico, estima-se o tamanho da fila (backlog) e retardo (delay) de bytes, conforme o conceito da álgebra Min-Plus. O algoritmo de policiamento proposto foi aplicado em um sistema de transmissão OFDM (Orthogonal Frequency - Division Multiplexing) / TDMA (Time Division Multiplexing Access) baseado no sistema WiMAX simplificado, onde se avaliou o desempenho da rede com os algoritmos de policiamento considerados. Realizam-se simulações com séries reais de tráfego de redes sem fio (Wi-Fi) e de redes com fio a fim de demonstrar a eficiência do algoritmo proposto em relação aos algoritmos de policiamento encontrados na literatura. As simulações realizadas evidenciam a eficiência do algoritmo MAPM em policiar séries reais de tráfego de redes com fio e redes sem fio. Propôs-se também, a utilização do Cálculo de Rede Determinístico associado ao processo envelope multifractal para se analisar o comportamento do tráfego em termos de retardo e backlog após a aplicação dos algoritmos de policiamento de rede. Por fim, são apresentados os resultados de retardo, backlog, utilização média do buffer e utilização do enlace para um sistema WiMAX onde o algoritmo de policiamento MAPM que apresentou em geral, acréscimo no retardo e backlog do tráfego em relação aos outros algoritmos e baixa utilização do enlace.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2016-12-16T13:58:28Z No. of bitstreams: 2 Tese - Flávio Geraldo Coelho Rocha - 2016.pdf: 4809831 bytes, checksum: e575d503488bc0e0cb8f1a1b3478d982 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-12-16T16:59:35Z (GMT) No. of bitstreams: 2 Tese - Flávio Geraldo Coelho Rocha - 2016.pdf: 4809831 bytes, checksum: e575d503488bc0e0cb8f1a1b3478d982 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-12-16T16:59:35Z (GMT). No. of bitstreams: 2 Tese - Flávio Geraldo Coelho Rocha - 2016.pdf: 4809831 bytes, checksum: e575d503488bc0e0cb8f1a1b3478d982 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-11-22 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / In this work, in order to describe network traffic characteristics, such as long-range dependence among samples, self-similarity and multiscale behavior, we propose a Multifractal Adaptive Model based on a multiscale cascade in the Wavelet Domain. We compare the proposed model performance with those of other models presented in the literature. It is also proposed an envelope process for the network traffic that takes into account parameters of the Multifractal Adaptive Model. Furthermore, we derive an equation in order to estimate the buffer overflow probability for both a simplified communication system with a single server, single queue and finite buffer, and to a wireless network multiuser scenario based on OFDM technology. To this end, we consider the service curve of the round-robin scheduling algorithm of the OFDM network. Taking into account the envelope process and the service curve we obtain, through the Network Calculus theory, the maximum delay experienced by users of the OFDM network. Moreover, assuming a similar network scenario to an LTE network, we propose a joint channel-aware and queue-aware resource scheduling algorithm. Based on the presented scheduler, we propose a minimum service curve for the LTE user and through this we propose an approach to accomplish maximum delay guarantee. / Neste trabalho, com o objetivo de descrever características do tráfego de redes, tais como longa-dependência entre amostras, autossimilaridade e comportamento multiescala, propõe-se um Modelo Multifractal Adaptativo baseado em uma cascata multiescala no domínio Wavelet. O desempenho do modelo proposto é comparado a outros modelos presentes na literatura. Também é proposto um processo envelope para o tráfego de redes que leva em consideração parâmetros do Modelo Multifractal Adaptativo proposto. Além disso, deduz-se uma equação para o cálculo da probabilidade de transbordo do buffer, tanto para um sistema de comunicação simplificado com servidor único, fila única e buffer finito, quanto para um ambiente multiusuário de rede sem fio baseado na tecnologia OFDM. Para tanto, utiliza-se a curva de serviço do escalonador round-robin da rede OFDM. Utilizando-se do processo envelope e da curva de serviço, obtém-se por meio do Cálculo de Rede a estimativa para o retardo máximo experimentado pelos usuários da rede OFDM. Em seguida, assume-se um ambiente de rede similar ao de uma rede LTE e propõe-se para essa rede um escalonador de recursos sensível às condições do canal de comunicação e à probabilidade de transbordo do buffer. Com base no escalonador apresentado, propõe-se uma curva de serviço mínima para o usuário da rede LTE e por meio dessa, propõe-se uma abordagem para garantia de retardo.