Submitted by Haroudo Xavier Filho (haroudo.xavierfo@ufpe.br) on 2016-04-06T17:23:43Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Andson_M_Balieiro_PhDThesis_ComputerScience_2015.pdf: 2709720 bytes, checksum: 2432ca198603426dffdf0ce2f34f3162 (MD5) / Made available in DSpace on 2016-04-06T17:23:43Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Andson_M_Balieiro_PhDThesis_ComputerScience_2015.pdf: 2709720 bytes, checksum: 2432ca198603426dffdf0ce2f34f3162 (MD5) Previous issue date: 2015-08-28 / FACEPE / The wireless technologies are progressing at a rapid pace such that the future of digital communication will be dominated by a dense, ubiquitous and heterogeneous wireless network. Along with this, there is a growing demand for wireless services with different requirements. In this respect, the management of this complex wireless ecosystem becomes challenging, and the wireless virtualization is pointed as an efficient solution to perform it, where different virtual wireless networks can be created, sharing and running on the same wireless infrastructure, and providing differentiated services to users. However, to satisfy the high demand for mobile communications, it is necessary the availability of a natural and scarce resource, the electromagnetic spectrum. Although the insertion of virtualization in wireless networks provides better resources utilization, the current approaches to employ the wireless virtualization can cause resource underutilization. To overcome this underutilization and enable that new wireless virtual networks can be deployed, the wireless virtualization can be combined with the cognitive radio technology and dynamic spectrum access (DSA) techniques in order to achieve the deepest level of wireless virtualization and to improve the resource utilization through the deployment of opportunistic resource sharing. Thus, virtual wireless networks with different access priorities to the resources (e.g. primary and secondary) can be deployed in an overlay form, sharing the same substrate wireless network, where the secondary virtual network (SVN) accesses the resources only when the primary one (PVN) is not using them. However, this new scenario brings new challenges: from the mapping to operation of these networks. The SVN mapping is a NP-hard problem and presents some constraints and objectives related to both PVNs and SVNs. Achieving all objectives simultaneously is a challenging process. This thesis addresses the SVNs mapping problem onto substrate network considering the existence of the PVNs on the same substrate network. It discloses the environment composed by these networks, denoted as cognitive radio virtual network environment (CRVNE), models this environment by using a M/M/N/N queue with preemptive and priority service, and delineates a multi-objective problem formulation for the SVNs mapping. Moreover, a scheme based on Genetic Algorithms to solve the SVNs mapping problem is proposed and evaluated in terms of collision, secondary user (SU) dropping, and SU blocking probabilities, and joint utilization, achieving better results than other based on the First-Fit strategy. / Recentemente, as tecnologias sem fio estão progredindo rapidamente de modo que o futuro da comunicação digital será dominado por uma rede sem fio densa, ubíqua e heterogênea. Adicionado a isso, existe uma demanda crescente por serviços sem fio com diferentes requisitos. Neste aspecto, o gerenciamento deste ecossistema complexo se tona desafiador e a virtualização sem fio é apontada como uma solução eficiente para realizá-lo, onde redes virtuais sem fio diferentes podem ser criadas, compartilhando e executando sobre a mesma infraestrutura de rede sem fio e provendo serviços diferenciados aos usuários. Entretanto, para satisfazer à alta demanda por comunicação móvel é necessária a disponibilidade de um recurso natural e escasso, o espectro eletromagnético. Embora a inserção de virtualização em redes sem fio forneça maior utilização dos recursos, as abordagens atuais para empregar a virtualização sem fio podem causar subutilização de recursos. Para superar esta subutilização, a virtualização sem fio pode ser combinada com a tecnologia de rádio cognitivo e técnicas de acesso dinâmico ao espectro (DSA) para alcançar o mais profundo nível de virtualização sem fio e melhorar a utilização de recursos através do compartilhamento oportunista deles. Assim, redes virtuais sem fio com diferentes prioridades de acesso aos recursos (ex. primária e secundária) podem ser implantadas sobrepostas, compartilhando a mesma infraestrutura de rede sem fio, onde as redes virtuais secundárias (SVNs) acessam os recursos somente quando as redes virtuais primárias (PVNs) não os estiverem utilizando. Entretanto, este novo cenário traz novos desafios, desde o mapeamento até a operação destas redes. O mapeamento de SVNs é um problema NP-difícil e apresenta restrições e objetivos relacionados tanto às PVNs quanto às SVNs. Alcançar todos os objetivos simultaneamente é um processo desafiador. Esta tese aborda o problema de mapeamento de SVNs em redes de substrato considerando a existência de PVNs na mesma rede de substrato. Ela apresenta o ambiente de redes virtuais de rádio cognitivo (CRVNE), modela este ambiente utilizando uma fila M/M/N/N preemptiva e com prioridade e delineia uma formulação multiobjetivo para o mapeamento de SVNs. Além disso, um esquema baseado em Algoritmos Genéticos (GA) para resolver o problema de mapeamento de SVNs é proposto e avaliado em termos das probabilidades de colisão, descarte de usuário secundário (US), bloqueio de US e utilização conjunta, alcançando melhores resultados do que um esquema baseado na estratégia First-Fit.

Submitted by PPG Ci?ncia da Computa??o (ppgcc@pucrs.br) on 2018-12-12T11:28:20Z No. of bitstreams: 1 Romulo Reis de Oliveira_DIS.pdf: 1719302 bytes, checksum: 005f38fa0c94cb6b97ce5f6ad6ec70ed (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-12-14T11:26:14Z (GMT) No. of bitstreams: 1 Romulo Reis de Oliveira_DIS.pdf: 1719302 bytes, checksum: 005f38fa0c94cb6b97ce5f6ad6ec70ed (MD5) / Made available in DSpace on 2018-12-14T11:50:26Z (GMT). No. of bitstreams: 1 Romulo Reis de Oliveira_DIS.pdf: 1719302 bytes, checksum: 005f38fa0c94cb6b97ce5f6ad6ec70ed (MD5) Previous issue date: 2015-04-24 / Hybrid synchrony virtual networks arose by combining network virtualization, which allows the co-existence of several virtual networks in the same shared physical substrate, providing infrastructure in a flexible and economic way, with partial synchrony network architecture, which is relevant in distributed systems in order to build reliable systems. One of the main challenges in network virtualization is the efficient mapping of virtual resources in the substrate network, since it is a NP-Hard complexity problem. When considering the synchrony of virtual and physical resources it becomes more difficult to map, making it unfeasible to calculate the optimal solution in real environments. Thus, heuristic approaches are necessary for finding semi-optimal solutions faster. In this work, four heuristics for mapping hybrid synchrony virtual networks are adapted. In order to evaluate these heuristics, two sets of experiments were executed. In the first set is compared the optimal solutions with their respective semi-optimal solutions, the results show the heuristics? efficiency are better when the virtual network requests are smaller, furthermore there were some semi-optimal solution mapping costs equivalent to the optimal solution mapping cost. The second set of experiments evaluates the heuristics performance using a physical substrate closer to real context and a larger number of virtual network requests. The results of this second set of experiments demonstrate that even with a larger number of virtual requests and a larger substrate, the solutions were computed in acceptable time. / As redes virtuais de sincronia h?brida surgiram da combina??o entre a virtualiza??o de redes, a qual permite a coexist?ncia de v?rias redes virtuais no mesmo substrato f?sico compartilhado fornecendo infraestrutura de maneira flex?vel e econ?mica, e arquitetura de redes com sincronia parcial, essa relevante em sistemas distribu?dos para construir sistemas confi?veis. Um dos principais desafios em virtualiza??o de redes ? o mapeamento eficiente dos recursos virtuais na rede de substrato, pois ? um problema de complexidade NP-Dif?cil. Ao considerar a sincronia dos recursos virtuais e f?sicos, se torna mais dif?cil efetuar esse mapeamento, inviabilizando o c?lculo da solu??o ?tima em ambientes reais. Sendo assim, abordagens heur?sticas s?o necess?rias para encontrar solu??es semi-?timas de maneira mais r?pida. Neste trabalho s?o adaptadas quatro abordagens heur?sticas para efetuar o mapeamento de redes virtuais de sincronia h?brida. Para avaliar o desempenho dessas heur?sticas foram efetuados dois conjuntos de experimentos. No primeiro conjunto de experimentos s?o comparadas as solu??es ?timas e as respectivas solu??es semi-?timas, os resultados indicaram que a efici?ncia das heur?sticas s?o melhores quando as requisi??es de redes virtuais s?o menores, al?m disso houveram alguns custos de solu??es semi-?timas equivalentes ao custo de mapeamento da solu??o ?tima. O segundo conjunto de experimento avalia o desempenho das heur?sticas utilizando um substrato de rede mais pr?ximo do contexto real e um maior n?mero de requisi??es de redes virtuais. Os resultados desse segundo experimento demonstram que mesmo com um n?mero maior de requisi??es de redes virtuais e um substrato maior, as solu??es foram calculadas em tempo aceit?vel.

The aim of this thesis is to provide an overview of the rights and obligations of mobile virtual network operators in the Czech Republic and the corresponding rights and obligations of mobile network operators. The first part of the paper looks at electronic communications in general. It begins with a description of the development of European Union electronic communications legislation, the currently valid Electronic Communications Act and its relation to the Code of Administrative Procedure. The paper then presents the legal regulation of administrative supervision, competition law, public consultation procedure, notification procedure and the procedural regulation of adopting a measure of general nature. The authority and the organization of the Czech Telecommunication Office (CTO) and a classification of the business models used by mobile virtual network operators is then detailed. The second part of the text addresses legal rules directly governing mobile virtual operators, commencing with the legal prerequisites for the provision of electronic communications services and a notification of intention to commence the provision of these services. A thorough exploration of the legal regulation of the access and interconnection and reference offers based upon this regulation is then included. The paper...

Virtual networks have changed the face of the information technology in current world. Many organizations today cooperate in virtual networks in order to meet the competition and the increased demands on technological development. Our focus in this thesis is on the information interchange in inter-organizational virtual networks. In this case the problem is related to the efficiency of the virtual networks for information interchange. This paper aim is to identify and discuss the possible aspects in the virtual networks efficient information interchange. This paper provides the detail information about the security aspects and its improvement and use of the efficient information interchange in inter organizational virtual network. This paper also provides the information that is helpful for improving the security in the virtual network so that the work in virtual network or the work via virtual network is efficient. / Program: Magisterutbildning i informatik

With the increasing popularity of information technologies, many companies try to set up a virtual network in order to share their business information. The purpose of creating such a virtual network is to create a new knowledge base on the combination of the existing knowledge. Collaboration is very necessary in such a virtual network as crass-unit collaboration takes place when people from different units work together in cross-unit teams on a common task or provide significant help to each other. Recently, co-design is an emerging technology in the field of informatics. It is considered as the development of system thinking, and it is a collaborative designing process which recruits designers, researchers, stakeholders and others together. The purpose of this collaborative activity is to sole designing problems. Therefore, if we want to increase collaboration in a co-design process, we need to look at a ways of increasing the efficiency of collaboration. The rapid development of accessible, reliable, and user-friendly information technology offers improvements to traditional collaboration, and makes new approaches possible. Many platforms for the exchange of information such as the Internet, email, and video-conferencing are well established aids to collaborative activities. Therefore, my research investigates to create an efficient virtual network for a co-design process. In this research, I will try to investigate that what is the need of a virtual network for co-design process and what are those virtual network soft-wares which can help us in a co-design process. My research discussion is related to the theory of CSCW (Computer Supported cooperative work). / Program: Magisterutbildning i informatik

A virtualização de redes é um mecanismo que permite a coexistência de múltiplas redes virtuais sobre um mesmo substrato físico. Um dos desafios de pesquisa abordados na literatura é o mapeamento eficiente de recursos virtuais em infraestruturas físicas. Embora o referido desafio tenha recebido considerável atenção, as abordagens que constituem o estado-da-arte apresentam alta taxa de rejeição, i.e., a proporção de solicitações de redes virtuais negadas em relação ao total de solicitações efetuadas ao substrato é elevada. Nesta dissertação, caracteriza-se, inicialmente, a relação entre a qualidade dos mapeamentos de redes virtuais e as estruturas topológicas dos substratos subjacentes. Avalia-se as soluções exatas de um modelo de mapeamento online sob diferentes classes de topologias de rede. A partir do entendimento dos fatores topológicos que influenciam diretamente o processo de mapeamento de redes virtuais, propõe-se uma estratégia para planejar a expansão de redes de provedores de infraestrutura de forma a reduzir consistentemente a taxa de rejeição de requisições de redes virtuais e melhor aproveitar os recursos ociosos da mesma. Os resultados obtidos evidenciam que grande parte das rejeições de redes virtuais ocorre em situações em que há grande disponibilidade de recursos, mas alguns poucos já saturados acabam inviabilizando, em função de características de conectividade do substrato, o atendimento de novas requisições. Ademais, os resultados obtidos utilizando a estratégia proposta evidenciam que o fortalecimento de partes-chave da infraestrutura levam a uma ocupação muito mais satisfatória. Uma expansão de 10% a 20% dos recursos da infraestrutura contribui para um aumento sustentado de até 30% no número de redes virtuais aceitas e de até 45% no aproveitamento dos recursos em comparação com a rede original. / Network virtualization is a mechanism that allows the coexistence of multiple virtual networks on top of a single physical substrate. One of the research challenges addressed recently in the literature is the efficient mapping of virtual resources on physical infrastructures. Although this challenge has received considerable attention, state-of-the-art approaches present, in general, a high rejection rate, i.e., the ratio between the number of denied virtual network requests and the total amount of requests is considerably high. In this thesis, we characterize the relationship between the quality of virtual network mappings and the topological structures of the underlying substrates. Exact solutions of an online embedding model are evaluated under different classes of network topologies. From the understanding of the topological factors that directly influence the virtual network embedding process, we propose an expansion strategy of physical infrastructure in order to suggest adjustments that lead to higher virtual network acceptance and, in consequence, to improved physical resource utilization. The obtained results demonstrate that most of rejections occur in situations in which a significant amount of resource is available, but a few saturated devices and links, depending on connectivity features of the physical substrate, hinder the acceptance of new requests. Moreover, the obtained results using the proposed strategy evidence that an expansion of 10% to 20% of the infrastructure resources leads to a sustained increase of up to 30% in the number of accepted virtual networks and of up to 45% in resource usage compared to the original network.

As the "network of network", the Internet has been playing a central and crucial role in modern society, culture, knowledge, businesses and so on in a period of over two decades by supporting a wide variety of network technologies and applications. However, due to its popularity and multi-provider nature, the future development of the Internet is limited to simple incremental updates. To address this challenge, network virtualization has been propounded as a potential candidate to provide the essential basis for the future Internet architecture. Network virtualization is capable of providing an open and flexible networking environment in which service providers are allowed to dynamically compose multiple coexisting heterogeneous virtual networks on a shared substrate network. Such a flexible environment will foster the deployment of diversified services and applications. A major challenge in network virtualization area is the Virtual Network Embedding (VNE), which aims to statically or dynamically allocate virtual nodes and virtual links on substrate resources, physical nodes and paths. Making effective use of substrate resources requires high-efficient and survivable VNE techniques. The main contribution of this thesis is two high-performance p-Cycle-based survivable virtual network embedding approaches. These approaches take advantage of p-Cycle-based protection techniques that minimize the backup resources while providing a full VN protection scheme against link and node failures.

Due to the existence of multiple stakeholders with conflicting goals and policies, alterations to the existing Internet architecture are now limited to simple incremental updates; deployment of any new, radically different technology is next to impossible. To fend off this ossification, network virtualization has been propounded as a diversifying attribute of the future inter-networking paradigm. In this talk, we provide an overview of the network virtualization environment (NVE) and address two basic problems in this emerging field of networking research. The identity management problem is primarily concerned with ensuring interoperability across heterogeneous identifier spaces for locating and identifying end hosts in different virtual networks. We describe the architectural and the functional components of a novel identity management framework (iMark) that enables end-to-end connectivity across heterogeneous virtual networks in the NVE without revoking their autonomy. The virtual network embedding problem deals with the mapping of virtual nodes and links onto physical network resources. We argue that the separation of the node mapping and the link mapping phases in the existing algorithms considerably reduces the solution space and degrades embedding quality. We propose coordinated node and link mapping to devise two algorithms (D-ViNE and R-ViNE) for the online version of the problem under realistic assumptions and compare their performance with the existing heuristics.

The current Internet presents a high barrier to entry for new service providers, due to its inability to accommodate new protocols and technologies, and lack of competition among the network providers. Recently, network virtualization has gained considerable attention as a possible solution, as it enables multiple networks to concurrently run over a shared substrate. It allows for deploying diverse network protocols and technologies customized for specific networked services and applications. Moreover, any party can take on the role of a network provider by simply offering his virtual network infrastructure to customers, increasing competition in the market. However, the first challenge in realizing a fair and competitive market in a virtual network environment is to have a service negotiation and contracting mechanism in place, that will allow (i) multiple infrastructure providers to participate in a fair and faithful competition, and (ii) a service provider to negotiate the price and quality of service with the providers. In this thesis, we present V-Mart, an open market model and enabling framework for automated service negotiation and contracting in a virtual network environment. To the infrastructure providers, V-Mart fosters an open and fair competition realized by a two stage auction. The V-Mart auction model ensures that bidders (infrastructure providers) bid truthfully, have the flexibility to apply diverse pricing policies, and still gain profit from hosting customers’ virtual resources. To the service providers, V-Mart offers virtual network partitioning algorithms that allow them to divide their virtual networks among competing infrastructure providers while minimizing the total cost. V-Mart offers two types of algorithms to suit different market scenarios. The algorithms not only consider virtual resource hosting price but also the service provider’s preference for resource co-location and the high cost of inter-provider communication. Through extensive simulation experiments we show the efficiency and effectiveness of the algorithms under various market conditions.

Due to the existence of multiple stakeholders with conflicting goals and policies, alterations to the existing Internet architecture are now limited to simple incremental updates; deployment of any new, radically different technology is next to impossible. To fend off this ossification, network virtualization has been propounded as a diversifying attribute of the future inter-networking paradigm. In this talk, we provide an overview of the network virtualization environment (NVE) and address two basic problems in this emerging field of networking research. The identity management problem is primarily concerned with ensuring interoperability across heterogeneous identifier spaces for locating and identifying end hosts in different virtual networks. We describe the architectural and the functional components of a novel identity management framework (iMark) that enables end-to-end connectivity across heterogeneous virtual networks in the NVE without revoking their autonomy. The virtual network embedding problem deals with the mapping of virtual nodes and links onto physical network resources. We argue that the separation of the node mapping and the link mapping phases in the existing algorithms considerably reduces the solution space and degrades embedding quality. We propose coordinated node and link mapping to devise two algorithms (D-ViNE and R-ViNE) for the online version of the problem under realistic assumptions and compare their performance with the existing heuristics.