In recent years, multi-core processors and multi-processor networks have grown in popularity as a solution to the limits on increasing clock speed, rising power consumption, and the nanometer manufacturing processes. Multi-core processors and multi-processor networks are seen as the next step in the advancement of computational capabilities by way of concurrent processing. However, parallel software design is difficult due to the immaturity of scalable architectures and software development environments for multi-core hardware. How should processors effectively and quickly pass information, with as little overhead as possible? What kind of communication architecture is best suited for parallelism? How can large-scale architectures be quickly produced, verified and properly utilized by software? Using commercially available FPGA development boards, Xilinx tools and components, this thesis offers a light-weight solution to these questions for effective, low-overhead, low-latency multi-core communication and fast prototyping of multi-processor networks for scalable processor arrays. / Master of Science

L'observation des systèmes complexes artificiels à grande échelle est difficile en raison de leur dimension et de leur ouverture. Cette thèse propose le modèle SMA-R (Système Multi-Agent Récursif) basé sur la récursivité pour l'observation multi-niveau des systèmes complexes artificiels. À partir d'un Système Multi-Agent donné, ce modèle est capable de construire une représentation abstraite multi-niveau. Le modèle d'agent récursif proposé possède un module contenant les connaissances, les capacités et le contexte de récursivité; un module pour observer les changements; deux mécanismes pour construire ou détruire les niveaux abstraits; un module d'interaction récursive prenant en charge des comportements collectifs et individuels. Pour appliquer ce modèle à des SMA physiquement décentralisés, nous avons proposé une architecture générique décentralisée d'agents récursifs en adoptant les concepts du modèle OSI qui offre en avant les capacités que nous cherchons: multi niveau, encapsulation, échange de messages virtuels et physiques... Un framework décentralisé générique a été développé permettant aux agents réels de construire les niveaux d'observation. Ce framework est appliqué à l'observation d'un réseau de capteurs sans fil. / Observation of large scale artificials systems is difficult because of their dimension and their openness. This thesis proposes a model SMA-R (Recursive Multi-Agent Systems) based on recursion for multi-level observation of artificial complex systems. From a given SMA, this model is able to build multi-level of abstractions. The model's agent has a module containning knowledge, skills and context of recursion, an eye to observe changes; two mechanisms to build or destroy an abstract level, a module of recursive interaction to support collective and individual behaviors. For applying this model to SMA physically decentralized, we proposed a generic decentralized architecture for recursive agent by adopting the concepts of the OSI model which offerts forward capabilities that we look for: multi-level encapsulation, exchange of virtual and physical messages ... A generic decentralized framework was developed allowing applicatives agents to build multi-levels observation. This framework is applied to the observation of a wireless sensor network.

Dans ce travail, nous présentons une approche de couplage de modèles orientée agent pour la modélisation des systèmes complexes spatiaux. L’idée principale est d’utiliser l’espace comme medium d’interaction entre les modèles à coupler pour leur permettre de coexister et d’interagir conformément à un ensemble de règles qui régissent ces interactions. En jouant le rôle de facteur de couplage, l’espace permet aux agents chargés du couplage d’échanger des données et nous permet d’observer les résultats concrets du couplage des différents modèles constituant le système complexe spatial étudié. Cette approche est composée d’une méthodologie et d’un métamodèle de couplage orienté-agent. Notre métamodèle est basé sur une architecture organisationnelle (AGRE) et de type holonique qui prend en considération la spécificité, l’autonomie et l’échelle de calcul de chaque modèle. Cette notion de holon nous permet de gérer l’hétérogénéité des formalismes et des échelles spatio-temporelles des modèles. En effet, l’hétérogénéité spatiale est gérée par la décomposition des agents de collecte et de spatialisation jusqu’à atteindre le niveau d’abstraction souhaité. Ces agents peuvent passer d’un niveau à l’autre en adaptant l’échelle spatiale de l’espace à l’échelle spatiale du modèle grâce à des fonctions de conversion. L’hétérogénéité temporelle est gérée par un agent de temps qui permettra de calculer la future date d’exécution du modèle et un agent scheduler qui se chargera de l’ordonnancement de ces dates sur l’échelle de temps de la simulation. Nous prenons le système urbain de Métouia (Tunisie), comme exemple de système complexe spatial à étudier pour répondre aux besoins des urbanistes en termes d’aide à la décision en aménagement et tester notre approche de couplage coupling4modeling. / In This work we present an agent-based approach for coupling models in the context of complex spatial systems. The main idea of our approach called Coupling4Modeling is the use of the space as a medium of interactions between the coupling agents to allow them to co-exist and interact according to a set of rules that govern these interactions. By playing the role of coupling factor, space allows coupling agents to exchange data and to observe the results of pragmatic coupling of different models constituting the studied spatial complex sys-tem. This approach consisting in a methodology and an agent-oriented metamodel of coupling. Our metamodel is based on an organizational (AGRE) with holonic architecture that takes into consideration the specificity, autonomy and the calculation scale of each model. This notion of holon allows us to manage the heterogeneity of formalisms and spatio-temporal scales of models. In fact, spatial heterogeneity is managed by the decomposition of the collector and the interpreter agents until reaching the desired level of abstraction. These agents can move from one level to another by adapting the spatial scale of the space to the spatial scale of the model through conversion functions. The temporal heterogeneity is managed by a time agent that will calculate the future date in the execution of the model and a scheduler agent that will schedule these dates following the time scale of the simulation. We take the urban system of Metouia (Tunisia) as an example of spatial complex system, to study with details and to test our coupling4modeling approach. The main goal is to meet the needs of urbanists in terms of decision support in urban planning and to test our coupling approach coupling4modeling.

La complexité associée à la coordination d’un groupe de robots mobiles est traitée dans cette thèse en investiguant plus avant les potentialités des architectures de commande multi-contrôleurs dont le but est de briser la complexité des tâches à exécuter. En effet, les robots mobiles peuvent évoluer dans des environnements très complexes et nécessitent de surcroît une coopération précise et sécurisée pouvant rapidement devenir inextricable. Ainsi, pour maîtriser cette complexité, le contrôleur dédié à la réalisation d’une tâche est décomposé en un ensemble de comportements/contrôleurs élémentaires (évitement d’obstacles et de collision entre les robots, attraction vers une cible, planification, etc.) qui lient les informations capteurs (provenant des capteurs locaux du robot, etc.) aux actionneurs des différentes entités robotiques. La tâche considérée dans cette thèse correspond à la navigation d’un groupe de robots mobiles dans des environnements peu ou pas connus en présence d’obstacles (statiques et dynamiques). La spécificité de l’approche théorique consiste à allier les avantages des architectures multi-contrôleurs à ceux des systèmes multi-agents et spécialement les modèles organisationnels afin d’apporter un haut niveau de coordination entre les agents/robots mobiles. Le groupe de robots mobiles est alors coordonné suivant les différentes normes et spécifications du modèle organisationnel. Ainsi, l’activation d’un comportement élémentaire en faveur d’un autre se fait en respectant les contraintes structurelles des robots en vue d’assurer le maximum de précision et de sécurité des mouvements coordonnés entre les différentes entités mobiles. La coopération se fait à travers un agent superviseur (centralisé) de façon à atteindre plus rapidement la destination désirée, les événements inattendus sont gérés quant à eux individuellement par les agents/robots mobiles de façon distribuée. L’élaboration du simulateur ROBOTOPIA nous a permis d’illustrer chacune des contributions de la thèse par un nombre important de simulations. / The difficulty of coordinating a group of mobile robots is adressed in this thesis by investigating control architectures which aim to break task complexity. In fact, multi-robot navigation may become rapidly inextricable, specifically if it is made in hazardous and dynamical environment requiring precise and secure cooperation. The considered task is the navigation of a group of mobile robots in unknown environments in presence of (static and dynamic) obstacles. To overcome its complexity, it is proposed to divide the overall task into a set of basic behaviors/controllers (obstacle avoidance, attraction to a dynamical target, planning, etc.). Applied control is chosen among these controllers according to sensors information (camera, local sensors, etc.). The specificity of the theoretical approach is to combine the benefits of multi-controller control architectures to those of multi-agent organizational models to provide a high level of coordination between mobile agents-robots systems. The group of mobile robots is then coordinated according to different norms and specifications of the organizational model. Thus, activating a basic behavior in favor of another is done in accordance with the structural constraints of the robots in order to ensure maximum safety and precision of the coordinated movements between robots. Cooperation takes place through a supervisor agent (centralized) to reach the desired destination faster ; unexpected events are individually managed by the mobile agents/robots in a distributed way. To guarantee performance criteria of the control architecture, hybrid systems tolerating the control of continuous systems in presence of discrete events are explored. In fact, this control allows coordinating (by discrete part) the different behaviors (continuous part) of the architecture. The development of ROBOTOPIA simulator allowed us to illustrate each contribution by many results of simulations.

Le travail de recherche présenté dans cette thèse s’inscrit dans la continuité des travaux de l’aide à la décision multi-critère de groupe (décideurs), particulièrement dans le champ de sélection de la localisation des centres de distribution. Dans un environnement certain, si la décision de sélection de la localisation des centres de distribution a donné lieu à plusieurs travaux de recherche, elle n’a jamais été l’objet, à notre connaissance, d’une décision prise par plusieurs décideurs. À cet égard, le premier objectif de cette thèse est de proposer une méthode d’aide à la décision multi-attribut et multi-acteur (MAADM) pour résoudre le problème posé. Pour se faire, nous avons adapté et étendu la méthode ELECTRE I. Dans un environnement incertain, au vu de l’incertitude inhérente et l’imprécision du processus décisionnel humain ainsi que les comportements futurs du marché et des entreprises, le deuxième objectif de cette thèse est de développer une méthode floue d’aide à la décision multi-attribut et multi-acteur (FMAADM) pour traiter le problème en question. Pour cela, nous avons couplé la méthode MAADM avec la théorie des ensembles flous. Pour la validation des deux contributions, nous avons conçu un système d’aide à la décision (S-DSS) pour implémenter les algorithmes de la méthode MAADM et la méthode FMAADM. Sur la base du S-DSS, deux études expérimentales ont été menées. Nous avons, aussi, appliqué une analyse de sensibilité pour vérifier la sensibilité de la solution retenue vis-à-vis aux variations de poids des critères d’évaluation. Les résultats obtenus prouvent que les deux méthodes proposées répondent à l’objectif recherché et ainsi retenues pour la sélection de la meilleure localisation dans un contexte certain/incertain de multi-attribut et multi-acteur. / The research work presented in this thesis is part of the works’ continuity on multi-criteria group (decision-makers) decision-making, particularly in the field of the distribution centers’ location selection. Under certain environment, although the decision to select the location of the distribution centers has given rise in several research works, it has never been the object, to our knowledge, of a decision taken by several decision makers. In this regard, the first objective of this thesis is to develop a multi-attribute and multi-actor decision-making method (MAADM) to resolve the posed problem. For this purpose, we have adapted and extended the ELECTRE I method. Under uncertain environment, In view of the inherent uncertainty and inaccuracy of human decision-making, the future behavior of the market and companies, the second objective of this thesis is to propose a fuzzy multi-attribute and multi-actor decision-making method (FMAADM) to treat the problem in question. To this end, we have coupled the MAADM method with the fuzzy set theory. To validate the two contributions, we designed a decision support system (S-DSS) to implement the MAADM method and the FMAADM method. Based on the S-DSS, two experimental studies were conducted. We also applied a sensitivity analysis to verify the sensitivity of the solution retained vis-a-vis to weights’ variations of evaluation criteria. The obtained results prove that the MAADM method and the FMAADM method meet the desired objective and thus retained for the selection of the best location under certain/uncertain context of multi-attribute and multi-actor.

Um subconjunto importante da pesquisa em sistemas multiagentes (SMA) baseiase no estudo das organizações. A organização define a estrutura do SMA e as regras que os agentes devem seguir, a fim de aumentar a eficiência do sistema. No entanto, dado um domínio, a escolha da organização que melhor resolve o problema ainda é uma questão sem resposta. Assim, abordagens empíricas para a avaliação de organizações são importantes, pois fornecem indícios valiosos sobre os custos e benefícios de diferentes configurações organizacionais, ajudando desenvolvedores e projetistas na definição da organização a ser adotada. Neste contexto, este trabalho, compara e avalia o impacto da mudança de parâmetros organizacionais no desempenho de um SMA, cujo objetivo é competir no cenário Agents on Mars proposto no Multi-Agent Programming Contest (MAPC). / An important subset of multi-agent systems (MAS) are based on the study of organizations. The organization defines the MAS structure and the rules which the agents must follow, increasing the MAS efficiency. Given an application domain, however, the choice of a particular organization that better solves the problem is still an open problem. Therefore, empirical approaches to the evaluation of organizations are important since they provide valuable evidences about the costs and benefits of different organizational settings, helping developers and designers to define the organization to be adopted. In this context, this work compares and evaluates the impact of organizational changes in the performance of a MAS, whose goal is to evolve in the \"Agents on Mars\" scenario proposed in the Multi-Agent Programming Contest (MAPC).

Um subconjunto importante da pesquisa em sistemas multiagentes (SMA) baseiase no estudo das organizações. A organização define a estrutura do SMA e as regras que os agentes devem seguir, a fim de aumentar a eficiência do sistema. No entanto, dado um domínio, a escolha da organização que melhor resolve o problema ainda é uma questão sem resposta. Assim, abordagens empíricas para a avaliação de organizações são importantes, pois fornecem indícios valiosos sobre os custos e benefícios de diferentes configurações organizacionais, ajudando desenvolvedores e projetistas na definição da organização a ser adotada. Neste contexto, este trabalho, compara e avalia o impacto da mudança de parâmetros organizacionais no desempenho de um SMA, cujo objetivo é competir no cenário Agents on Mars proposto no Multi-Agent Programming Contest (MAPC). / An important subset of multi-agent systems (MAS) are based on the study of organizations. The organization defines the MAS structure and the rules which the agents must follow, increasing the MAS efficiency. Given an application domain, however, the choice of a particular organization that better solves the problem is still an open problem. Therefore, empirical approaches to the evaluation of organizations are important since they provide valuable evidences about the costs and benefits of different organizational settings, helping developers and designers to define the organization to be adopted. In this context, this work compares and evaluates the impact of organizational changes in the performance of a MAS, whose goal is to evolve in the \"Agents on Mars\" scenario proposed in the Multi-Agent Programming Contest (MAPC).

One of the main challenges posed by 4G wireless communication systems is achieving flexible, programmable multi-standard radio transceivers with maximum hardware share amongst different standards at a minimum power consumption. Evaluating the feasibility and performance of different multi-standard/multi-band radio solutions at an early stage, i.e. system level, is key for succeeding in surmounting this challenge. This entails for- mulation of the transceiver budget for several RF architectures and frequency plans with different degrees of hardware sharing. This task is complicated by the fact that transceiver blocks can have different implementations that lead to different performances. The tools that are available for use at present have only analysis capabilities or address only one standard and/or receiver architecture at a time.In the belief that a new approach to this problem is necessary, the work that has led to this thesis proposes a novel methodology that automates the design-space explo- ration of integrated multi-standard wireless radio receivers. This methodology has been implemented in a multi-standard RF Transceiver Architecture Comparison Tool, TACT. TACT helps surmounting many of the challenges faced by RF system designers targeting multi-standard/multi-band radio receivers.The goal of the algorithms TACT is built upon is to find a multi-standard receiver frequency plan and budget that meets or exceeds the specifications of the addressed wire- less standards while keeping the requirements of each of the receiver blocks as relaxed as possible. TACT offers RF engineers a deep insight into the receiver behavior at a very early stage of the design flow. It models the impact of critical circuit non-idealities using a high level of abstraction. This reduces the number of design iterations and, thus, the time-to-market of the solution. The reuse of already available intellectual property (IP) blocks is also considered in TACT, what can result in a significant cost reduction of the receiver implementation. A combination of a behavioural-based cooperative multi-agent optimization and deterministic techniques is proposed.The capabilities of the proposed techniques and developed tool are illustrated through case studies addressing different design challenges the design of multi-standard receivers present.The last part of this thesis is devoted to one of the key blocks of any communica- tions receiver: the analog-to-digital converter. This work focuses on modeling and design methodologies for continuous-time ΔΣ modulators. A method to evaluate the stability margin of continuous-time ΔΣ modulators as a function of the timing uncertainty effects is proposed. / QC 20100907 / RaMSiS

A wireless channel is shared by all devices, in the vicinity, that are tuned to the channel, and at any given time, only one of the devices can transmit information. One way to overcome this limitation, in throughput capacity, is to use multiple orthogonal channels for different devices, that want to transmit information at the same time. In this work, we consider the use of multiple orthogonal channels in wireless data networks. We explore algorithms and protocols for such multi-channel wireless networks under two broad categories of network-wide and link-level challenges. Towards handling the network-wide issues, we consider the channel assignment and routing issues in multi-channel wireless networks. We study both single radio and multi-radio multi-channel networks. For single radio multi-channel networks, we propose a new granularity for channel assignment, that we refer to as component level channel assignment. The strategy is relatively simple, and is characterized by several impressive practical advantages. For multi-radio multi-channel networks, we propose a joint routing and channel assignment protocol, known as Lattice Routing. The protocol manages channels of the radios, for the different nodes in the network, using information about current channel conditions, and adapts itself to varying traffic patterns, in order to efficiently use the multiple channels. Through ns2 based simulations, we show how both the protocols outperform other existing protocols for multi-channel networks under different network environments. Towards handling the link-level challenges, we identify the practical challenges in achieving a high data-rate wireless link across two devices using multiple off-the-shelf wireless radios. Given that the IEEE 802.11 a/g standards define 3 orthogonal wi-fi channels in the 2.4GHz band and 12 orthogonal wi-fi channels in the 5GHz band, we answer the following question: ``can a pair of devices each equipped with 15 wi-fi radios use all the available orthogonal channels to achieve a high data-rate link operating at 600Mbps?' Surprisingly, we find through experimental evaluation that the actual observed performance when using all fifteen orthogonal channels between two devices is a mere 91Mbps. We identify the reasons behind the low performance and present Glia, a software only solution that effectively exercises all available radios. We prototype Glia and show using experimental evaluations that Glia helps achieve close to 600Mbps data-rate when using all possible wi-fi channels.

L'observation des systèmes complexes artificiels à grande échelle est difficile en raison de leur dimension et de leur ouverture. Cette thèse propose le modèle SMA-R (Système Multi-Agent Récursif) basé sur la récursivité pour l'observation multi-niveau des systèmes complexes artificiels. À partir d'un Système Multi-Agent donné, ce modèle est capable de construire une représentation abstraite multi-niveau. Le modèle d'agent récursif proposé possède un module contenant les connaissances, les capacités et le contexte de récursivité; un module pour observer les changements; deux mécanismes pour construire ou détruire les niveaux abstraits; un module d'interaction récursive prenant en charge des comportements collectifs et individuels. Pour appliquer ce modèle à des SMA physiquement décentralisés, nous avons proposé une architecture générique décentralisée d'agents récursifs en adoptant les concepts du modèle OSI qui offre en avant les capacités que nous cherchons: multi niveau, encapsulation, échange de messages virtuels et physiques... Un framework décentralisé générique a été développé permettant aux agents réels de construire les niveaux d'observation. Ce framework est appliqué à l'observation d'un réseau de capteurs sans fil.