<p>   The need for RF spectrum for the rapidly growing broadband access services is evident. Cognitive radio is an emerging technology that aims to introduce secondary usage of the spectrum resources without interfering with the primary usage of the licensed users but with a lower priority.</p><p>   Signal detection for cognitive radios has drawn a lot of interest in the research community, where different algorithms are suggested. The most commonly used algorithms are energy detection, feature detection, eigenvalue based detection. Energy detection is the simplest and most common way to detect signals. It has fast sensing time but poor performance. The feature detection and eigenvalue based detection methods are more sophisticated and offer better performance but they are more complex and expensive. This thesis will present the pros and cons of each method and offer comparisons between them.</p><p>   To evaluate the performance of different algorithms used in cognitive radio, different research testbeds have been suggested in the literature. Some of the most frequently used testbeds are based on GNU-radio, WARP, or BEE2. GNU-radio is the simplest testbed and is free, but it has low bandwidth and poor performance. WARP and BEE2 are more advanced testbeds. They offer good performance and are easy to update, but they are more complex and expensive. These three testbeds will be described, compared, and their advantages and disadvantages will be observed in this thesis.</p>

The need for RF spectrum for the rapidly growing broadband access services is evident. Cognitive radio is an emerging technology that aims to introduce secondary usage of the spectrum resources without interfering with the primary usage of the licensed users but with a lower priority.    Signal detection for cognitive radios has drawn a lot of interest in the research community, where different algorithms are suggested. The most commonly used algorithms are energy detection, feature detection, eigenvalue based detection. Energy detection is the simplest and most common way to detect signals. It has fast sensing time but poor performance. The feature detection and eigenvalue based detection methods are more sophisticated and offer better performance but they are more complex and expensive. This thesis will present the pros and cons of each method and offer comparisons between them.    To evaluate the performance of different algorithms used in cognitive radio, different research testbeds have been suggested in the literature. Some of the most frequently used testbeds are based on GNU-radio, WARP, or BEE2. GNU-radio is the simplest testbed and is free, but it has low bandwidth and poor performance. WARP and BEE2 are more advanced testbeds. They offer good performance and are easy to update, but they are more complex and expensive. These three testbeds will be described, compared, and their advantages and disadvantages will be observed in this thesis.

Made available in DSpace on 2014-06-12T15:58:07Z (GMT). No. of bitstreams: 2 arquivo3257_1.pdf: 820624 bytes, checksum: 0b5a95bb7462b1b6322093ade6c7e5f9 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A pesquisa em Engenharia de Software precisa de mais evidências, principalmente em tópicos que envolvem interação humana, como manutenção de software. Muito embora pesquisa empírica esteja ganhando mais interesse, técnicas, metodologias e melhores práticas ainda estão em debate. Testbeds são ambientes empíricos nos quais pesquisadores podem planejar e executar estudos com a intenção de avaliar e/ou comparar tecnologias. O conceito é bem difundido em outras áreas, como Redes de Computadores, mas permanece pouco explorado na Engenharia de Software. O objetivo desta dissertação e agregar estudos relevantes que definem testbeds para avaliar tecnologias em Engenharia de Software. Para alcançar este objetivo, um Mapeamento Sistemático de Estudos da literatura de testbeds em Engenharia de Software foi executado. Baseado em buscas realizadas em mecanismos automatizados e buscas manuais em conferências importantes na área de Engenharia de Software, um total de 4239 estudos foi obtido. Treze (13) estudos primários foram identificados como relevantes e classificados de acordo com quatro perguntas de pesquisa. A partir da análise realizada, o estudo conclui que o uso de testbeds é benéfico em vários cenários. Importantes contribuições deste trabalho são: fornecer informações importantes para aqueles que desejam desenvolver testbeds, reduzir o tempo necessário para um tecnologia ser amplamente utilizada e disseminar o conceito pela comunidade.

Development of Cognitive Radio (CR) applications, which rely on a radio's ability to adapt intelligently to it's spectral surroundings will soon make the all important technological jump from research interest to systems integration, as demand for highly adaptive wireless applications expand. VT-CORNET (Virginia Tech – Cognitive Radio Network Testbed) is a unique testbed concept, designed to facilitate this technology leap by offering researchers — both local and remote — the opportunity to conduct CR experiments on an installed infrastructure of highly flexible radio nodes. These nodes — 48 in total — are distributed throughout four floors of a building on the Virginia Tech campus, and provide researchers with diverse options in terms of channel conditions and deployment scenarios. The radios themselves consist of the widely used USRP2 Software Defined Radio (SDR) platform, coupled to a centrally located cluster of rack servers — which provide a high performance GPP environment for real-time software based signal processing. VT-CORNET is specially licensed to operate our low-power nodes over a broad range of frequencies, which provides researcher the opportunity to conduct experiments on live spectrum — in the presence of real primary users. Testbeds are a widely used tool in the wireless and networking fields, and VT-CORNET expands the concept through a focus on CR research and education. This thesis describes the construction and deployment of the CORNET testbed in detail. Specific contributions made to the testbed include the design and implementation of the management network, as well as the initial deployment of the SDR nodes in the ceiling. In addition, this thesis describes the administration and management of the CORNET GPP cluster, and provides a instructions for the basic usage of CORNET from an administrative and user perspective. Finally, this thesis describes a number of custom SDR waveforms implemented on CORNET which demonstrate the utility of the testbed for cognitive radio applications. / Master of Science

No description available.

Cette thèse propose une approche générique pour automatiser des expériences sur des réseaux quelle que soit la technologie utilisée ou le type de plate-forme d'évaluation. L'approche proposée est basée sur l'abstraction du cycle de vie de l'expérience en étapes génériques à partir desquelles un modèle d'expérience et des primitives d'expérimentation sont dérivés. Une architecture générique d'expérimentation est proposée, composée d'un modèle d'expérience générique, d'une interface pour programmer des expériences et d'un algorithme d'orchestration qui peux être adapté aux simulateurs, émulateurs et bancs d'essai de réseaux. La faisabilité de cette approche est démontrée par la mise en œuvre d'un framework capable d'automatiser des expériences sur toute combinaison de ces plateformes. Trois aspects principaux du framework sont évalués : son extensibilité pour s'adapter à tout type de plate-forme, son efficacité pour orchestrer des expériences et sa flexibilité pour permettre des cas d'utilisation divers, y compris l'enseignement, la gestion des plate-formes et l'expérimentation avec des plates-formes multiples. Les résultats montrent que l'approche proposée peut être utilisée pour automatiser efficacement l'expérimentation sur les plates-formes d'évaluation hétérogènes et pour un éventail de scénarios variés. / This thesis proposes a generic approach to automate network experiments for scenarios involving any networking technology on any type of network evaluation platform. The proposed approach is based on abstracting the experiment life cycle of the evaluation platforms into generic steps from which a generic experiment model and experimentation primitives are derived. A generic experimentation architecture is proposed, composed of an experiment model, a programmable experiment interface and an orchestration algorithm that can be adapted to network simulators, emulators and testbeds alike. The feasibility of the approach is demonstrated through the implementation of a framework capable of automating experiments using any combination of these platforms. Three main aspects of the framework are evaluated: its extensibility to support any type of platform, its efficiency to orchestrate experiments and its flexibility to support diverse use cases including education, platform management and experimentation with multiple platforms. The results show that the proposed approach can be used to efficiently automate experimentation on diverse platforms for a wide range of scenarios.

Made available in DSpace on 2014-12-17T15:48:09Z (GMT). No. of bitstreams: 1 DhiegoFC_DISSERT.pdf: 2315369 bytes, checksum: 0b56b1d402d2c768528a0bcc9847d87f (MD5) Previous issue date: 2014-03-31 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / A Wireless Mesh Network (WMN - Wireless Mesh Network) IEEE 802.11s standard to become operational it is necessary to configure the parameters that meet the demands of its users, as regards, for example, the frequency channels, the power antennas, IPs addresses, meshID, topology, among others. This configuration can be done via a CLI (Command - Line Interface) or a remote interface provided by the equipment manufacturer, both are not standardized and homogeneous, like black boxes for the developers, a factor that hinders its operation and standardization. The WMN, as a new standard, is still in the testing phase, and tests are necessary to evaluate the performance of Path Discovery Protocol, as in this case of HWMP (Hybrid Wireless Mesh Protocol), which still has many shortcomings. The configuration and test creation in a WMN are not trivial and require a large workload. For these reasons this work presents the AIGA, a Management Integrated Environment for WMN IEEE 802.11s, which aims to manage and perform testbeds for analyzes of new Path Discovery Protocols in a WMN / Por serem redes com diversas caracter?sticas interessantes como auto-organiza??o e toler?ncia a falhas, as Wireless Mesh Networks (WMN) vem sendo estudadas a bastante tempo pela comunidade cient?fica. Muitos desses estudos tipicamente s?o conduzidos utilizando redes em ambientes controlados conhecidos como testbeds. Al?m disso, ap?s a conclus?o do processo de padroniza??o do IEEE 802.11s as WMN baseadas nessa tecnologia vem sendo cada vez mais utilizadas como redes de produ??o nas organiza??es. Como s?o redes bastante flex?veis no que diz respeito ao seu modo de opera??o, pois suportam um elevado n?mero de par?metros de configura??o, a tarefa de gerenciamento dessas redes tende a ser muito complexa. N?o existe uma configura??o ideal que atenda a qualquer cen?rio, sendo preciso identificar o conjunto de valores que oferecem o melhor desempenho para cada caso. Desse modo, ap?s a configura??o da rede ? importante verificar se ela se comporta conforme esperado. Para isso, ? necess?rio injetar tr?fego na rede e monitorar seu comportamento. Este trabalho prop?e o AIGA, um Ambiente Integrado de Ger?ncia para Redes em Malha Sem Fio IEEE 802.11s, que facilita o gerenciamento de WMNs de produ??o bem como da utiliza??o de testbeds para realiza??o de experimentos

Self-reconfigurable robotic systems are variable-morphology machines capable of changing their overall structure by rearranging the modules they are composed of. Individual modules are capable of connecting and disconnecting to and from one another, which allows the robot to adapt to changing environments. Optimally reconfiguring such systems is computationally prohibitive and thus in general self-reconfiguration approaches aim at approximating optimal solutions. Nonetheless, even for approximate solutions, centralized methods scale poorly in the number of modules. Therefore, the objective of this research is the development of decentralized self-reconfiguration methods for modular robotic systems. Building on completeness results of the centralized algorithms in this work, decentralized methods are developed that guarantee stochastic convergence to a given target shape. A game-theoretic approach lays the theoretical foundation of a novel potential game-based formulation of the self-reconfiguration problem. Furthermore, two extensions to the basic game-theoretic algorithm are proposed that enable agents to modify the algorithms' parameters during runtime and improve convergence times. The flexibility in the choice of utility functions together with runtime adaptability makes the presented approach and the underlying theory suitable for a range of problems that rely on decentralized local control to guarantee global, emerging properties. The experimental evaluation of the presented algorithms relies on a newly developed multi-robotic testbed called the "Robotarium" that is equipped with custom-designed miniature robots, the "GRITSBots". The Robotarium provides hardware validation of self-reconfiguration on robots but more importantly introduces a novel paradigm for remote accessibility of multi-agent testbeds with the goal of lowering the barrier to entrance into the field of multi-robot research and education.

With the growth of Internet, the underlying protocols are increasingly challenged by new technologies and applications. The original Internet protocols were, however, not designed for wireless communication, mobility, long disconnection times, and varying bandwidths. In this thesis, we study challenged networking, and how well old and new protocols operate under such constraints. Our study is experimental. We build network testbeds and measure the performance of alternative protocols and architectures. We develop novel methodologies for repeatable experiments that combine emulations, simulations and real world experiments. Based on our results we suggest modifications to existing protocols, and we also develop a new network architecture that matches the constraints of a challenged network, in our case, an opportunistic network. One of our most important contributions is an Ad hoc Protocol Evaluation (APE) testbed. It has been successfully used worldwide. The key to its success is that it significantly lowers the barrier to repeatable experiments involving wireless and mobile computing devices. Using APE, we present side-by-side performance comparisons of IETF MANET routing protocols. A somewhat surprising result is that some ad hoc routing protocols perform a factor 10 worse in the testbed than predicted by a common simulation tool (ns-2). We find that this discrepancy is mainly related to the protocols’ sensing abilities, e.g., how accurately they can infer their neighborhood in a real radio environment. We propose and implement improvements to these protocols based on the results. Our novel network architecture Haggle is another important contribution. It is based on content addressing and searching. Mobile devices in opportunistic networks exchange content whenever they detect each other. We suggest that the exchange should be based on interests and searches, rather than on destination names and addresses. We argue that content binding should be done late in challenged networks, something which our search approach supports well.

Computer networking researchers often have access to a few different network testbeds (Section 1.2) for their experiments. However, those testbeds are limited in resources; contentions for resources are prominent in those testbeds especially when conference deadline is looming. Moreover, services running on those testbeds are subject to seasonal and daily tra c spikes from users all round the world. Hence, demand for resources at the testbeds are high. Some researchers can use other testbeds in conjunction with the ones they are using. Even though each of the testbeds may have different infrastructures, and characteristics, in the end, what the researchers receive in return is a set of computing resources, either virtual machines or physical machines. Essentially, those testbeds are providing a similar service, but researchers have to manage the credentials for accessing the testbeds manually, and they have to manually request resources from different testbeds in order to setup experiments that span across different testbeds. This thesis presents GENICloud, a project that enables the federation of testbeds with clouds. Computing and storage resources can be provisioned to researchers and services running on existing testbeds dynamically from an Eucalyptus cloud. As a part of the GENICloud project, the user proxy (Section 3.4) provides a less arduous method for testbeds administrators to federate with other testbeds; the same service also manages researchers credentials, so they do not have to acquire resources from each testbed individually. The user proxy provides a single interface for researchers to interact with di erent testbeds and clouds and manage their experiments. Furthermore, GENICloud demonstrates that there are, in fact, quite a few architectural similarities between different testbeds and even clouds.