Dissertations / Theses on the topic 'Multiservice networks'

The research focuses in devising decentralised and distributed control system architecture for the management of internetworking systems to provide improved service delivery and network control. The theoretical basis, results of simulation and implementation in a real-network are presented. It is demonstrated that better performance, utilisation and fairness can be achieved for network customers as well as network/service operators with a value based control system. A decentralised control system framework for analysing networked and shared resources is developed and demonstrated. This fits in with the fundamental principles of the Internet. It is demonstrated that distributed, multiple control loops can be run on shared resources and achieve proportional fairness in their allocation, without a central control. Some of the specific characteristic behaviours of the service and network layers are identified. The network and service layers are isolated such that each layer can evolve independently to fulfil their functions better. A common architecture pattern is devised to serve the different layers independently. The decision processes require no co-ordination between peers and hence improves scalability of the solution. The proposed architecture can readily fit into a clearinghouse mechanism for integration with business logic. This architecture can provide improved QoS and better revenue from both reservation-less and reservation-based networks. The limits on resource usage for different types of flows are analysed. A method that can sense and modify user utilities and support dynamic price offers is devised. An optimal control system (within the given conditions), automated provisioning, a packet scheduler to enforce the control and a measurement system etc are developed. The model can be extended to enhance the autonomicity of the computer communication networks in both client-server and P2P networks and can be introduced on the Internet in an incremental fashion. The ideas presented in the model built with the model-view-controller and electronic enterprise architecture frameworks are now independently developed elsewhere into common service delivery platforms for converged networks. Four US/EU patents were granted based on the work carried out for this thesis, for the cross-layer architecture, multi-layer scheme, measurement system and scheduler. Four conference papers were published and presented.

The central cause of strain on today's IP network infrastructure steins from the industries striving to extend the network to carry voice and other advanced services that it was not designed for. This thesis develops the reasons why more sophisticated mechanisms are required for ensuring that the best-effort infrastructure becomes both predictable and controllable, if the current IP infrastructure is to replace circuit switched networks. The main theme of the thesis are the IP traffic engineering (IPTE) traffic engineering algorithms that were developed by the author. The goal of the proposed approach is to compute a set of Open Shortest Path First (OSPF) link weights to balance network load, while honouring bandwidth, hop count and propagation delay constraints of the traffic. The proposed solution is built on classical OSPF routing and additionally uses the multi topology concepts that were recently proposed as an extension to OSPF. Using Multi Topology OSPF (mt-OSPF), multiple routing planes can be implemented. Each Multi Topology (MT) routing plane is assigned its own link metrics and thus traffic can be routed independently. Given a traffic demand matrix and the network topology, the algorithm computes a set of link weights using a search heuristic. The optimisation is cost function based, so that individual constraints can be taken into account per routing plane. Using this approach, constraint information remains in the "offline" IPTE algorithms and thus no extra constraint awareness is required at layer 3. Since recent Cisco implementations of mt-OSPF and Multi Topology IS-IS (M-ISIS) provide the required multi topology routing support, no major changes at the router level are required for the approach to be realised. Extensive simulations presented in this thesis show that IPTE has the potential to provide the differentiated routing and load balancing that it was designed for. In addition the simulations show that load is balanced more evenly across the network than with standard shortest path routing on inverse capacity link weights. A network management system is discussed that acts as the binding element for all enabling components. A simplified architecture for such a management system is presented and it is discussed how several traffic engineering mechanisms could coexist with IPTE on one network infrastructure. The use of the authors IPTE approach in the context of this management system is discussed in depth: Dangers associated with potential network disruption caused by frequent link weight modifications are analysed from both intra- and inter-domain point of view. A strategy for solving the problem of disruptions caused by link weight changes is presented by using several network planes to migrate traffic, rather than causing disruptions to a "live" plane through link weight modification and resulting OSPF routing table updates. The strategy is simulated, showing that any detrimental effects of the transition are avoidable. However, the work is ongoing and the results presented are indicative. Overall the thesis presents an approach for traffic engineering using traditional routing techniques, to (1) preserve the original intrinsic advantages of the IP design and (2) help ready IP networking for the much more restricting requirements of the future mutiservice network. It presents algorithms, simulations and frameworks showing how the work fits into the current IP networking world.

The problem of estimating call blocking probabilities in ATM networks is addressed in this thesis. We develop a new, two-step iterated framework for call acceptance control (CAC). In the first step, we define a new variable bit rate (VBR) traffic descriptor called effective rate and we use a known effective bandwidth technique in the second step to estimate cell loss. This approach yields decoupled estimators at the call level so that loss systems models can be used to perform network analysis. Our work on loss systems is divided in three parts: single-link problems, reservation and network problems. In the single-link context, we generalize existing asymptotic approximation formulae for blocking probabilities and propose a uniform estimate under light up to critical loading conditions. We present the salient features of commonly used reservation schemes while proposing and reviewing ways to estimate blocking probabilities in each case. In the case of networks, we provide an overview of classical techniques to evaluate blocking probabilities such as fixed-point methods. We propose a novel fixed-point technique for large capacity systems which yields dramatic reduction in computational complexity. We also analyze loss networks from an analytic point of view using the Laplace method and a change of probability law technique. We obtain asymptotic formulae for every loading conditions and a number of asymptotic results regarding network behavior. Many numerical examples are provided as well as a model example where we illustrate how our asymptotic formulae can be used to perform network optimization.

LIMA, F. R. M. Maximizing spectral efficiency under minimum satisfaction constraints on multiservice wireless networks. 2012. 124 f. Tese (Doutorado em Engenharia de Teleinformática) - Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2012.
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Cellular networks are now a new player in the competitive market of data service provision mainly due to the technological advances of 3rd Generation (3G) and the upcoming 4th Generation (4G). Long Term Evolution (LTE) and LTE-Advanced are examples of systems that are capable of providing high data rates to the end user. The need of being connected anytime and anywhere and the appealing mobile devices/applications are strong indications that the mobile broadband market has potential for further worldwide increasing. This new scenario with sophisticated mobile terminals enables the quick popularization of new appealing data mobile applications. As a consequence, it is expected that the traffic on mobile networks will have a considerable increase in the next years. Therefore, the sustainable Quality of Service (QoS) provision of heterogeneous services appears as a challenging scenario for mobile network operators and industry in the near future. In order to deal with this challenging scenario, improvements in the core network have been done by means of an Internet Protocol (IP)-based packet-switched architecture. In the radio access network, the use of Orthogonal Frequency Division Multiple Access (OFDMA) and Single Carrier - Frequency Division Multiple Access (SC-FDMA) as the multiple access schemes of downlink and uplink of LTE system, respectively, and the addition of multiple antennas techniques have boosted the achieved data rates in the radio part of the networks. Another relevant functionality that is useful to deal with the challenges of next generation cellular networks is efficient Radio Resource Allocation (RRA). RRA algorithms interact with multiple access schemes and multiple antenna schemes and are responsible for the management of the scarce radio resources such as power, time slots, spatial channels and frequency chunks. In this context, we study in this thesis the use of RRA in cellular networks in order to improve the resource usage efficiency and guarantee the sustainable provision of multiple services. More specifically, we model this RRA problem as the optimization problem of maximizing the overall data rate subject to minimum satisfaction constraints per service. Along this thesis, we study this problem in different scenarios with different multiple access strategies and multiple antennas schemes. As main contributions we provide the characterization of optimal solutions, proposal of low-complexity heuristic solutions, performance evaluation by means of computational simulations and computational complexity analysis of the involved algorithms.
Redes celulares entraram recentemente no competitivo mercado de provimento de serviços de dados devido principalmente aos avanços tecnológicos da terceira geração (3G) e da iminente quarta geração (4G). Os sistemas Long Term Evolution (LTE) e LTE-Advanced são exemplos de redes celulares que proporcionam altas taxas de dados a seus usuários. A necessidade de estar conectado de forma permanente e os novos e poderosos dispositivos móveis são fortes indicadores que o mercado de banda larga móvel ainda possui potencial de crescimento em nível global. Este novo cenário com sofisticados dispositivos móveis permite a rápida popularização de novas aplicações de dados móveis. Como consequência, esperamos que o tráfego nas redes móveis tenham um aumento considerável nos próximos anos. Portanto, o provimento de Qualidade de Serviço (do inglês, Quality of Service (QoS)) para serviços heterogêneos consiste em um cenário desafiador para os operadores dos sistemas e indústria em um futuro próximo. De forma a enfrentar esses desafios, algumas melhorias foram realizadas no núcleo da rede por meio do advento da arquitetura por chaveamento por pacotes baseado em protocolo da internet (do inglês, Internet Protocol (IP)). Na rede de acesso de rádio, tivemos como avanços o uso de múltiplas antenas nos nós da rede e a adoção dos esquemas de múltiplo acesso por divisão de frequências ortogonais (do inglês, Orthogonal Frequency Division Multiple Access (OFDMA)) e múltiplo acesso por divisão de frequências com portadora única (do inglês, Single Carrier - Frequency Division Multiple Access (SC-FDMA)) nos enlaces direto e reverso do sistema LTE, respectivamente. Outra funcionalidade que destacamos como relevante para enfrentar os desafios das próximas gerações de redes celulares consiste no uso de alocação de recursos de rádio (do inglês, Radio Resource Allocation (RRA)). Algoritmos de RRA são responsáveis pelo gerenciamento dos recursos de rádio tais como intervalos de tempo (do inglês, time slots), canais espaciais e grupos de frequências que em geral são escassos. Neste contexto, nós estudamos nesta tese o uso de RRA em redes celulares de forma a melhorar a eficiência no uso dos recursos e garantir um provimento sustentável de múltiplos serviços. Especificamente, modelamos RRA como o problema de otimização de maximização da taxa total de transmissão sujeito a restrições de satisfação mínimas por serviço. Este problema é estudado ao longo da tese em diferentes cenários resultantes da combinação de diferentes esquemas de múltiplo acesso e múltiplas antenas. Como principais contribuições temos a caracterização de soluções ótimas, propostas de heurísticas de baixa complexidade, avaliação de desempenho por meio de simulações computacionais e por fim a análise da complexidade dos algoritmos envolvidos.

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This study investigates the problem of ring-node assignment a Multiservice SDH/SONET Optical network design with constraints in capacity and differential delay. The problem is characterized as a graph-partitioning problem, and a heuristic algorithm based on constraints programming satisfaction technology is proposed.

Internet of Things (IoT) has come in reality to improve our living quality. Automation is embraced in all the possible business verticals that have diverse communication needs ranged from static devices’ sporadic transmission to mobile devices’ every minute transmission. Despite, there are many technologies available today to support IoT services; cellular systems can play a vital role for IoT services, like wearables, vehicular, and industrial IoT, rollout which have either mobility or security concern.  IoT services generated traffic are foreseen as a sporadic-bursty traffic. As the cellular networks are designed to serve continuous data traffic, the existing system’s access control mechanism cannot efficiently conform to the burstiness of traffic. This limits the scope of the network scalability in terms of simultaneous serving devices’ capacity. Also, this bursty pattern can extensively increase the rate of network’s congestion incident. In this thesis, we focus on these underlying challenges to support a large number of heterogeneous IoT services with existing services over the same radio network. An important question for supporting IoT services over cellular networks is how detrimental are the effects of IoT services on other services of cellular networks. This dissertation seeks to answer this with quantitative results to indicate the real constraints of existing networks. An important conclusion is that existing cellular system is incompetent to support the bursty arrival of massive IoT devices in terms of radio networks’ access control plane’s scalability. Therefore, this dissertation presents solutions to overcome the identified limitations of access control planes. To improve the performance of the access control plane, we incorporate a vertical core network controlled group management scheme that can assure the operator’s granular control over capillary gateways. Besides, this introduces a unique handover opportunity between cellular and capillary network vertices. Then, we present a simple but efficient initial access mechanism to overcome the initial access collision at the very early stage. Finally, we show the impact of access collision and retransmission on the initial access resource dimensioning.We present a practical traffic model that is realistic for the traffic scenario for mixed-traffic. Our presented results and analysis depict the trade-offs between access rate, retransmission and resource allocation over time and frequency.Our results reveal that with proposed schemes of the cellular system’s access control plane can be scalable and resilient to accommodate a large number of IoT devices without incurring extra delay or need of resources to the system.

QC 20170928

The concept of Next Generation Network NGN (Next Generation Network), which uses TCP / IP technology as a basis for building multiservice networks, gives the operator great opportunities to organize a virtually unlimited number of services. But at the same time it sets new challenges in terms of creating and implementing new methods of traffic service. The struggle for resources affects the quality of service for all types of traffic, including IPTV traffic. The modern model of differentiated service provides for the division of traffic into classes with giving them different priorities in service. The problem of establishing priorities for different types of traffic was solved by the method of reducing individual quality indicators to a generalized value function of the additive type using weights.

The successful operation of peer-to-peer network depends on the resilience of its peer‘s communications. On the Internet, direct communications between peers are often limited by restrictions like NATs and traffic filtering. Addressing such problem is particularly pressing for peer-to-peer networks that do not wish to rely on any trusted infrastructure, which might otherwise help the participant establish communication channels. Modern peer-to-peer networks employ various techniques to address the problem of restricted connectivity on the Internet. One interesting development is that various overlay networks now support multiple communication protocols to improve resilience and counteract service degradation.

This PhD thesis considers some of the more emerging problems in network modelling, namely the design of survivable hierarchical networks, Traffic Engineering (TE) and generally traffic management in survivable multi-service networks with Quality of Service (QoS) prerequisites and the planning of wireless access networks. So, in the context of the research work presented in this thesis:- Novel survivable hierarchical network design, wireless access network planning and traffic management techniques were developed. These techniques involve optimisation methods based on Linear Programming (LP) and Integer Linear Programming (ILP), as well as heuristic methods based on graph theory  and computational intelligence (genetic optimisation and simulated annealing). A unified framework for off-line TE, on-line/dynamic routing and path restoration (facility restoration) that can be used in survivable multi-service QoS networks was also developed. Existing traffic management techniques were improved so that to support advanced QoS and survivability characteristics. At first, the objectives of this project are presented followed by a brief analysis of the problems encountered in the network design process. Next, the new methods for designing survivable hierarchical networks are analytically described followed by the developed wireless access network design techniques. After that, the novel traffic management methods and the aforementioned framework, developed in the context of this thesis are presented. Test results are provided together with most of the developed methods. The test results actually indicate that the developed methods can efficiently solve small, medium or even large problems, all developed methods are computationally tractable and the performance of the developed heuristic method is very close to this of the corresponding LP and ILP optimisation methods. The new heuristic methods are solved in a fraction of the time (less than 30%) that the equivalent optimisation methods are solved. Note that the specially developed design and simulation software tool NetLab was used in order to test and evaluate the new design and traffic management methods. Finally, a summary of the work carried out and the results achieved is presented followed by the conclusions and suggestions for further work.

The significant advances in fiber-optic technology have broadened the optical network\'s reach into end-user business premises and even homes, allowing new services and technologies to be delivered to the customers. The next wave of innovation will certainly generate numerous opportunities provided by the widespread popularity of emerging solutions and applications such as tactile Internet, telemedicine and real time 3-D content generation, making them part of everyday life. Nevertheless, to support such an unprecedented and insatiable demand of data traffic, higher capacity and security, flexible bandwidth allocation and cost-efficiency have become crucial requirements for technologies candidate for future optical access networks. To this aim, optical code-division multiple-access (OCDMA) technology is considered as a prospective candidate, particularly due to features like asynchronous transmissions, flexible as well as conscious bandwidth resource distribution and support to differentiated services at the physical layer, to name but a few. In this context, this thesis proposes new mathematical formalisms for bit error rate, packet throughput and packet delay to assess the performance of flexible OCDMA networks capable of providing multiservice multirate transmissions according to users\' requirements. The proposed analytical formalisms do not require the knowledge a priori of the users\' code sequences, which means that the network performance can be addressed in a simple and straightforward manner using the code parameters only. In addition, the developed analytical formalisms account for a general number of distinct users\' classes as well as general probability of interference among users. Hence, these formalisms can be successfully applied for performance evaluation of flexible OCDMA networks not only under any number of users\' classes in a network, but also for most spreading codes with good correlation properties. The packet throughput expression is derived assuming Poisson, binomial and Markov chain approaches for the composite packet arrivals with the latter defined as benchmark. Then, it is shown via numerical simulation the Poisson-based expression is not appropriate for a reliable throughput estimate when compared to the benchmark (Markov) results. The binomial-based throughput equation, by its turn, provides results as accurate as the benchmark. In addition, the binomial-based throughput is numerically more convenient and computationally more efficient than the Markov chain approach, whereas the Markov-based one is computationally expensive, particularly if the number of users is large. The bit error rate (BER) expressions are derived considering gaussian and binomial distributions for the multiple-access interference and it is shown via numerical simulations that accurate performance of flexible OCDMA networks is only obtained with the binomial-based BER expression. This thesis also proposes and investigates a network architecture for Internet protocol traffic over flexible OCDMA with support to multiservice multirate transmissions, which is independent of the employed spreading code and does not require any new optical processing technology. In addition, the network performance assumes users transmitting asynchronously using receptors based on intensity-modulation direct-detection schemes. Numerical simulations shown that the proposed network performs well when its users are defined with high-weight code or when the channel utilization is low. The BER and packet throughput performance of an OCDMA network that provides multirate transmissions via multicode technique with two codes assigned to each single user is also addressed. Numerical results show that this technique outperforms classical techniques based on multilength code. Finally, this thesis addresses a new breakthrough technology that might lead to higher levels of security at the physical layer of optical networks. This technology consists in the generation of deterministic chaos from a commercial free-running vertical-cavity surface-emitting laser (VCSEL). The chaotic dynamics is generated by means of mechanical strains loaded onto an off-the-shelf quantum-well VCSEL using a simple and easily replicable holder. Deterministic chaos is then achieved, for the first time, without any additional complexity of optical feedback, parameter modulation or optical injection. The simplicity of the proposed system, which is based entirely on low-cost and easily available components, opens the way to the widespread use of commercial and free-running VCSEL devices for chaos-based applications. This off-the-shelf and cost-effective optical chaos generator has the potential for not only paving the way towards new security platforms in optical networks like, for example, successfully hiding the user information in an unpredictable, random-like signal against eventual eavesdroppers, but also for influencing emerging chaos applications initially limited or infeasible due to the lack of low-cost solutions. Furthermore, it leads the way to future realization of emerging applications with high-integrability and -scalability such as two-dimensional arrays of chaotic devices comprising hundreds of individual sources to increase requirements for random bit generation, cryptography or large-scale quantum networks.
Os avanços relacionados a tecnologia fotônica ampliaram o alcance das redes de comunicação óptica tanto em instalações de estabelecimentos comerciais quanto em residências, permitindo que novos serviços e tecnologias fossem entregues aos clientes. A próxima onda de inovação certamente gerará inúmeras oportunidades proporcionadas pela popularidade de soluções emergentes e aplicações como a Internet tátil, a telemedicina e a geração de conteúdo 3-D em tempo real, tornando-os parte da vida cotidiana. No entanto, para suportar a crescente demanda de tráfego atual, uma maior capacidade e segurança, alocação flexível de largura de banda e custo-eficiência tornaram-se requisitos cruciais para as tecnologias candidatas a futuras redes de acesso óptico. Para este fim, a tecnologia de acesso múltiplo por divisão de código óptico (OCDMA) é considerada um candidato em potencial, particularmente devido a características como transmissões assíncronas, distribuição flexível de banda larga e suporte a serviços diferenciados na camada física, para citar apenas alguns. Neste contexto, esta tese propõe novos formalismos matemáticos para a taxa de erro de bits, taxa de transferência de pacotes e atraso de pacotes para avaliar o desempenho de redes OCDMA flexíveis capazes de fornecer transmissões em múltiplas qualidades de serviço (QoS) de acordo com as necessidades dos usuários. Os formalismos analíticos propostos não requerem o conhecimento a priori das sequências de código dos usuários, o que significa que o desempenho da rede pode ser abordado de forma simples e direta usando apenas os parâmetros de código. Além disso, os formalismos analíticos desenvolvidos representam um número geral de classes de usuários distintos, bem como a probabilidade geral de interferência entre os usuários. Portanto, esses formalismos podem ser aplicados com sucesso na avaliação de desempenho de redes OCDMA flexíveis não apenas em qualquer número de classes de usuários em uma rede, mas também para a maioria dos códigos de espalhamento com boas propriedades de correlação. A expressão de taxa de transferência de pacotes é derivada assumindo aproximações de Poisson, binomial e de cadeia de Markov para as chegadas de pacotes compostos, com a última definida como benchmark. Em seguida, é mostrado via simulação numérica que a expressão baseada em Poisson não é apropriada para uma estimativa confiável de taxa de transferência quando comparada aos resultados de benchmark (Markov). A equação de taxa de transferência binomial, por sua vez, fornece resultados tão precisos quanto o benchmark. Além disso, a taxa de transferência binomial é numericamente mais conveniente e computacionalmente eficiente quando comparada com abordagem de Markov, enquanto esta última é computacionalmente dispendiosa, particularmente se o número de usuários é grande. As expressões de taxa de erro de bit (BER) são derivadas considerando distribuições gaussianas e binomiais para a interferência de acesso múltiplo e é mostrado por meio de simulações numéricas que o desempenho exato de redes OCDMA flexíveis é obtido somente com a expressão binomial de BER. Esta tese também propõe e investiga uma arquitetura de rede para o tráfego de protocolo de Internet sobre OCDMA flexível com suporte a transmissões de QoS e de múltiplas taxas, que é independente do código de espalhamento empregado e não requer qualquer nova tecnologia de processamento óptico. Além disso, o desempenho da rede assume que os usuários transmitem de forma assíncrona usando receptores baseados em esquemas de detecção direta de modulação de intensidade. As simulações numéricas mostraram que a rede proposta possui melhor desempenho quando seus usuários são definidos com peso de código alto ou quando a utilização do canal é baixa. O desempenho da BER e da taxa de transferência de pacotes de uma rede OCDMA que fornece transmissões de múltiplas taxas por meio de uma técnica multi-código com dois códigos atribuídos a cada usuário é também abordado. Os resultados numéricos mostram que esta técnica supera as técnicas clássicas baseadas no código de comprimento múltiplo. Finalmente, esta tese aborda uma nova tecnologia que pode levar a níveis mais elevados de segurança na camada física de redes ópticas. Esta tecnologia consiste na geração de caos determinístico a partir de um laser de emissão superficial com cavidade vertical (VCSEL). A dinâmica caótica é gerada através da aplicação de forças mecânicas em um VCSEL comercial usando um suporte simples e facilmente replicável. O caos determinístico é então alcançado, pela primeira vez, sem qualquer complexidade adicional de realimentação óptica, modulação de parâmetros ou injeção óptica. A simplicidade do sistema proposto, o qual se baseia inteiramente em componentes de baixo custo e que são facilmente encontrados, abre o caminho para o uso de dispositivos VCSEL comerciais para aplicações baseadas em caos. Este gerador de caos óptico tem o potencial não só de pavimentar o caminho para novas plataformas de segurança em redes ópticas, como, por exemplo, ocultar com êxito as informações do usuário em um sinal imprevisível e aleatório contra eventuais invasores, como também tem o potencial de influenciar aplicações de caos emergentes inicialmente limitadas ou inviáveis devido à falta de soluções de baixo custo. Além disso, ele conduz o caminho para a realização futura de aplicações emergentes com alta integridade e escalabilidade, tais como matrizes bidimensionais de dispositivos caóticos que compreendem centenas de fontes individuais para aumentar as necessidades de geração de bit aleatória, criptografia ou redes quânticas de grande escala.

Orientador: Lee Luan Ling
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Resumo: O provisionamento de QoS garantida é de extrema importância no desenvolvimento das futuras redes. Os recentes avanços tecnológicos em comutação e em transmissão permitem a implementação de redes com velocidades extremamente altas que podem transportar grandes quantidades de tráfego geradas por aplicações mais sensíveis aos requisitos de qualidade de serviço. A próxima geração de redes deverá suportar novas aplicações multimídia em um ambiente global e disponibilizar novos serviços em plataformas flexíveis sem necessidade de alteração da infra-estrutura. Isto requer uma nova arquitetura de redes capaz de oferecer serviços de transporte e de processamento para aplicações de comunicação com fortes requisitos de QoS. No amplo escopo da engenharia de tráfego de redes e do provimento de serviços com qualidade assegurada, esta tese se dedica a propor algumas soluções para os problemas de alocação de recursos de rede, em especial soluções para a estimação da banda efetiva. Para tanto, se utiliza de forma intensiva a caracterização de tráfego, métodos analíticos, heurísticos e de simulação. Os métodos propostos de alocação de banda neste estudo estão fundamentados na Teoria dos Grandes Desvios, aproximação Gaussiana e de caracterização de tráfego. Em termos de caracterização de tráfego, além de vários parâmetros já adotados na literatura é abordada a teoria fractal, incluindo mono e multifractais em seus diferentes aspectos, e ainda, é introduzido um novo parâmetro de tráfego que inclui as características mono e multifractal. Adicionalmente são consideradas as restrições de atraso e jitter, através de adoção de critérios para validação da estimação da banda efetiva, para tráfego em tempo real. A validação da metodologia proposta neste trabalho foi efetivada através de exaustivos testes de simulação com arquivos de tráfego real
Abstract: The assured QoS provisioning has great importance in the development of future networks. Recently, the technological advances in transmission and switching has allowed the implementation of very high speed networks which can transport a huge amount of traffic generated by QoS sensitive applications. The next generation networks must support new multimedia applications in a global environment and deliver new services over flexible platforms without the need of change in the infrastructure. That means that the new network architecture has to be able to transport and process information with strong QoS requirements. Under the wide scope of teletraffic engineering and assured quality of service provisioning, this thesis proposes solutions for some open problems of network resource allocation, especially bandwidth allocation. In order to get reliable solutions, we use intensive traffic characterization, analytical and heuristical methods and simulations. The proposed bandwidth allocation methods in this study are based on the Large Deviation Theory, Gaussian Approximation and traffic characterization. In terms of traffic characterization, in addition to the well known traffic parameters, the fractal theory, including mono and multifractals, are considered. Besides, we introduce a new traffic parameter that takes the mono and multifractal characteristics into account. The proposed bandwidth estimation approaches were tested with real real time traffic under both delay and jitter criteria. All proposed methodologies in this work have been validated by exhaustive simulation tests with real traffic traces
Doutorado
Telecomunicações e Telemática
Doutor em Engenharia Elétrica

The continuous evolution of the optical communication technology in the last few years has allowed the growing users demand for higher bandwidth to be satisfactorily attended. This new demand is mainly attributed to the growing popularity of bandwidth-intensive networking applications, such as Internet protocol television (IPTV), high-definition television (HDTV), e-learning, e-health, super high-definition (SHD) class digital movies, and e-culture based on 3-D full-HD video. These applications will eventually require differentiated service types and diversified data rates. As a result, capability of supporting differentiated-quality of service (QoS) and multirate transmission are becoming a challenge for future optical networks. Among many multiplexing techniques, optical code-division multiple-access (OCDMA) constitutes a potential candidate for next generation optical networks, particularly due to features like asynchronous operation, simplified network control, easy addition of new users, and possibility of differentiated-QoS at the physical layer. The performance of this access technique is mainly limited by multiple-access interference (MAI). Although in multirate, multiservice OCDMA systems MAI is considered to be binomially distributed, others probability distributions for the MAI analyzes and consequently the bit error rate (BER) have been used as an approximation. In this context, this dissertation proposes a new formalism to evaluate the BER performance of 1-D and 2-D multirate, multiservice OCDMA systems considering MAI as binomially distributed, resulting in a more accurate BER expression. Also, the proposed approach does not require knowledge a priori of the generated code sequences themselves, which means that the system performance analysis is achieved more easily using only the code parameters. Furthermore, a multirate OCDMA system employing 1-D optical orthogonal code (OOC) and 2-D optical fast frequency hopping (OFFH) codes is also investigated. A performance comparison in terms of BER for the OOC-based system assuming both Poisson and binomial distribution for the MAI is investigated. A further comparison of an OFFH-based multirate system assuming both gaussian and binomial distribution for the MAI is also analyzed. It is shown that BER performance in multirate scenarios can be overestimated or underestimated by many orders of magnitude depending on the assumed distribution for the MAI and on the number of simultaneous users. Moreover, it is presented for the first time a hybrid OCDM/WDM optical packet switch capable of supporting multirate and differentiated-QoS transmission. The architecture of the proposed multirate switch and its performance in terms of packet loss probability are also presented. Finally, it is shown that using a gaussian or Poisson distribution for the MAI might not be appropriate for a reliable BER estimate, since they are not acceptable approximations to assess the performance of multirate, multiservice systems with good accuracy.
A contínua evolução da tecnologia de comunicações ópticas observada nos últimos anos vem possibilitando atender a crescente demanda dos usuários por maior largura de banda. Esta nova demanda é atribuída principalmente à popularidade crescente de aplicações de banda larga, tais como TV por protocolo de Internet (IPTV), televisão de alta definição (HDTV), ensino online, e-saúde, filmes digitais de super alta definição (SHD) e e-cultura baseado em vídeo 3-D full-HD. Esta vasta gama de aplicações acabará por necessitar de tipos de serviços diferenciados e taxas de transmissão de dados diversificadas. Como resultado, capacidades de suportar diferenciamento de qualidade de serviço (QoS) e transmissão de múltiplas taxas estão se tornando um desafio para as redes ópticas futuras. Dentre muitas técnicas de multiplexação existentes, OCDMA constitui-se em um candidato potencial para as redes ópticas de próxima geração, particularmente devido a características como operação assíncrona, controle de rede simplificada, fácil adição de novos usuários, e também possibilidade de QoS diferenciado na camada física. O desempenho desta técnica de acesso múltiplo é limitado principalmente por interferência múltipla de acesso (MAI). Embora em sistemas OCDMA de múltiplas taxas e multiserviços a MAI deva ser considerada binomialmente distribuída, outras distribuições de probabilidade para a análise da MAI e, consequentemente, da BER têm sido utilizadas como uma aproximação. Neste contexto, este trabalho propõe um novo formalismo para avaliar o desempenho da BER de sistemas OCDMA 1-D e 2-D de múltiplas taxas e multisserviços considerando a MAI como binomialmente distribuída, o que resulta em uma expressão mais precisa para a BER. Além disso, o método proposto neste trabalho não requer conhecimento, a priori, das sequências de códigos geradas, o que significa que a análise do desempenho do sistema é obtida mais facilmente utilizando apenas os parâmetros do código. Um sistema OCDMA de múltiplas taxas empregando códigos 1-D OOC e 2-D OFFH será também investigado. Uma comparação do desempenho em termos de BER para o sistema baseado em OOC supondo tanto a distribuição de Poisson quanto a binomial para a MAI é investigada. De forma análoga, uma comparação para o sistema de múltiplas taxas baseado em OFFH supondo desta vez tanto a distribuição gaussiana quanto a binomial para a MAI também é analisada. É mostrado que a BER em cenários de múltiplas taxas pode ser superestimada ou subestimada em várias ordens de grandeza, dependendo da distribuição suposta para a MAI e do número de usuários simultâneos no sistema. Além disso, é apresentado pela primeira vez um switch óptico híbrido de pacotes OCDM/WDM capaz de prover transmissões de múltiplas taxas e serviços diferenciados. A arquitetura do switch proposto e seu desempenho em termos de probabilidade de perda de pacotes também são apresentados. Finalmente, é mostrado que o uso da distribuição gaussiana ou poissoniana para a MAI pode não ser apropriado para uma estimativa confiável de BER, uma vez que não são aproximações aceitáveis para avaliar o desempenho de sistemas de múltiplas taxas e multiserviços com boa precisão.

Les avancées technologiques ont permis la commercialisation à grande échelle de terminaux mobiles. De ce fait, l’homme est de plus en plus connecté et partout. Ce nombre grandissant d’usagers du réseau ainsi que la forte croissance du contenu disponible, aussi bien d’un point de vue quantitatif que qualitatif saturent les réseaux et l’augmentation des moyens matériels (passage à la fibre optique) ne suffisent pas. Pour surmonter cela, les réseaux doivent prendre en compte le type de contenu (texte, vidéo, ...) ainsi que le contexte d’utilisation (état du réseau, capacité du terminal, ...) pour assurer une qualité d’expérience optimum. A ce sujet, la vidéo fait partie des contenus les plus critiques. Ce type de contenu est non seulement de plus en plus consommé par les utilisateurs mais est aussi l’un des plus contraignant en terme de ressources nécéssaires à sa distribution (taille serveur, bande passante, …). Adapter un contenu vidéo en fonction de l’état du réseau (ajuster son débit binaire à la bande passante) ou des capacités du terminal (s’assurer que le codec soit nativement supporté) est indispensable. Néanmoins, l’adaptation vidéo est un processus qui nécéssite beaucoup de ressources. Cela est antinomique à son utilisation à grande echelle dans les appareils à bas coûts qui constituent aujourd’hui une grande part dans l’ossature du réseau Internet. Cette thèse se concentre sur la conception d’un système d’adaptation vidéo à bas coût et temps réel qui prendrait place dans ces réseaux du futur. Après une analyse du contexte, un système d’adaptation générique est proposé et évalué en comparaison de l’état de l’art. Ce système est implémenté sur un FPGA afin d’assurer les performances (temps-réels) et la nécessité d’une solution à bas coût. Enfin, une étude sur les effets indirects de l’adaptation vidéo est menée
On the one hand, technology advances have led to the expansion of the handheld devices market. Thanks to this expansion, people are more and more connected and more and more data are exchanged over the Internet. On the other hand, this huge amound of data imposes drastic constrains in order to achieve sufficient quality. The Internet is now showing its limits to assure such quality. To answer nowadays limitations, a next generation Internet is envisioned. This new network takes into account the content nature (video, audio, ...) and the context (network state, terminal capabilities ...) to better manage its own resources. To this extend, video manipulation is one of the key concept that is highlighted in this arising context. Video content is more and more consumed and at the same time requires more and more resources. Adapting videos to the network state (reducing its bitrate to match available bandwidth) or to the terminal capabilities (screen size, supported codecs, …) appears mandatory and is foreseen to take place in real time in networking devices such as home gateways. However, video adaptation is a resource intensive task and must be implemented using hardware accelerators to meet the desired low cost and real time constraints.In this thesis, content- and context-awareness is first analyzed to be considered at the network side. Secondly, a generic low cost video adaptation system is proposed and compared to existing solutions as a trade-off between system complexity and quality. Then, hardware conception is tackled as this system is implemented in an FPGA based architecture. Finally, this system is used to evaluate the indirect effects of video adaptation; energy consumption reduction is achieved at the terminal side by reducing video characteristics thus permitting an increased user experience for End-Users

Було проведено дослідження у ході якого виявлено, що процес конфігурації мультисервісних мереж вимагає багато часу адміністратора. Розроблено програмне забезпечення, графічний інтерфейс якого дозволяє автоматично зконфігурувати інтерфейси роутера, налаштувати сервіси за обраною технологією VoIP або IPTV (multicast). Система дозволяє швидко та зручно перенести згенерований код налаштувань маршрутизатора в налаштування реального мережевого обладнання. Систему реалізовано у формі програмного забезпечення з графічним інтерфейсом з використанням мови програмування Java.

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The telecommunications services quality, as well as several other products in the telecommunications area, is strongly linked to the suppliers services levels quality. These services levels can, however, be measured andevaluated by objective criteria and from a service level agreement between service supplier and customer, this agreement is called SLA. In this study a methodology is proposed for the elaboration of the SLA documentation model, that takes care the business model necessity.This methodology is structuralized in the politics and processes of service quality described by the international norms and standards like Management Forum, ITU, IETF and ITIL. The modeling of the SLA documentation was applied in a practical case of multi-service networks, based in IP networks, resulting in the system specification of the quality service level to be contracted with services supplier. The application of this methodology resulted in improvements for both sides, regarding the reduction in operational costs, the correction of processes and procedures, and a high reliability and transparency in the commercial relation.
A qualidade dos servi?os de telecomunica??es, assim como a de v?rios outros produtos da ?rea de telecomunica??es, est? fortemente ligada aos n?veis de qualidade de servi?os prestados pelos fornecedores. Esses n?veis de servi?os podem, no entanto, ser medidos e avaliados por meio de fatores e crit?rios objetivos, a partir de um N?vel de Servi?o acordado entre o provedor do servi?o e o cliente, chamado de SLA. Neste estudo ? proposta uma metodologia para elabora??o de modelo de documenta??o SLA. Essa metodologia est? estruturada na pol?tica e nos processos de qualidade de servi?o descritos nas normas e padr?es internacionais do TeleManagement Forum, ITU ,IETF e ITIL. A modelagem da documenta??o SLA foi aplicada em um caso pr?tico de rede de multiservi?os, baseada em redes IP, resultando na especifica??o do sistema de n?vel de qualidade de servi?o a ser contratado do provedor de servi?os. Na aplica??o dessa metodologia obteve-se ganhos para ambos os lados, com refer?ncia a redu??o de custo operacional, na corre??o de processos e procedimentos e uma alta confiabilidade e transpar?ncia na rela??o comercial.

В кваліфікаційній роботі здійснено процес оцінювання ефективності мультисервісної мережі засобами комп'ютерного імітаційного моделювання LabView. Розроблено імітаційну модель мультисервісної мережі для моделювання її поведінки при різних сценаріях із використанням технології Riverbed Modeler. Оцінено ефективність мультисервісної мережі із застосуванням засобів імітаційного моделювання з різними параметрами мережі при використанні протоколів IPv4 та IPv6. На підставі отриманих результатів моделювання мережевих сценаріїв здійснено процедуру порівняння ефективності роботи протоколів IРv4 і IРv6. Оцінено ефективність мультисервісної мережі із застосуванням засобів імітаційного моделювання при різних параметрів мережі при використанні VLAN.
In the qualification work the process of evaluating the efficiency of the multiservice network by means of computer simulation modeling LabView is carried out. A simulation model of a multiservice network has been developed to model its behavior in different scenarios using Riverbed Modeler technology. The efficiency of the multiservice network with the use of simulation tools with different network parameters using IPv4 and IPv6 protocols is evaluated. Based on the obtained results of network scenario modeling, the procedure of comparing the efficiency of IPv4 and IPv6 protocols was carried out. The efficiency of the multiservice network with the use of simulation tools at different network parameters when using VLAN is evaluated.
ВСТУП 7 РОЗДІЛ 1. АНАЛІТИЧНА ЧАСТИНА 9 1.1. Протокол IPv4 9 1.2. Протокол IPv6 21 1.3. Мережі VLAN 26 1.4. Висновки до розділу 1 31 РОЗДІЛ 2. ОСНОВНА ЧАСТИНА 32 2.1. Типова схема досліджуваної мультисервісної мережі зв'язку 32 2.2. Технологія Riverbed Modeler 33 2.3. Висновки до розділу 2 36 РОЗДІЛ 3. НАУКОВО-ДОСЛІДНА ЧАСТИНА 37 3.1. Порівняння ефективності роботи протоколів IРv4 і IРv6 37 3.2. VLAN-канали по послугах 49 3.3. Висновки до розділу 3 54 РОЗДІЛ 4. ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ 56 4.1. Охорона праці 56 4.2. Безпека в надзвичайних ситуаціях 58 4.3. Висновки до розділу 4 60 ЗАГАЛЬНІ ВИСНОВКИ 61 ПЕРЕЛІК ПОСИЛАНЬ 62 Додаток А. Копія тези конференції 67

碩士
國立臺灣科技大學
電機工程技術研究所
86
In broadband multiservice networks (e.g., B-ISDN with ATM),various services(e.g., voice, video, and data) share the network resources (e.g., transmission lines and switches). Such multiservice networks must satisfy the quality of service (QoS)for each individual service. But various services might differ in QoS and characteristics. For example, generally speaking, voice and video are delay-sensitive but loss-insensitive, while data isdelay-insensitive but loss-sensitive. Furthermore, the bandwidth requirement for video is usually large than for voice. We concentrate on the delay-sensitive voice and video as well asthe delay-insensitive data. Such voice and video are buffered and are allocated one particular bandwidth. Various CBR services might have different bandwidth requirement and arrival process (e.g., Bernoulli, Possion, Pascal). To regulate call blocking probabilitiesof CBR services, trunk reservation is employed to enforce admission control. For delay-insensitive data, finite buffer is used to minimize cell loss probability, while keeping the average delayunder a maximum value. First, a broadband multiservice multiplexer is studied, and approximations for performance measures (call blocking probability, cell average delay and loss probability) are derived. Moreover, some results are gerneralized to multirate loss network (e.g., star network). The resulting estimate is checked with computer simulation which is also used to establish the interaction pattern between individual service QoS and overall system performance.

碩士
國立台灣工業技術學院
電機工程技術研究所
85
In broadband multiservice networks (e.g., B-ISDN with ATM), various services(e.g., voice, video, and data) share the network resources (e.g., transmission lines and switches). Such multiservice networks must satisfy the quality of service (QoS) for each individual service. But various services might differ in QoS and characteristics. For example, generally speaking, voice and video are delay-sensitive but loss-insensitive, while data isdelay-insensitive but loss-sensitive. Furthermore, the bandwidth requirement for video is usually large than for voice. We concentrate on the delay-sensitive voice and video as well asthe delay-insensitive data. Such voice and video are buffered and are allocated one particular bandwidth. Various CBR services might have different bandwidth requirement and arrival process (e.g., Bernoulli, Possion, Pascal). To regulate call blocking probabilitiesof CBR services, trunk reservation is employed to enforce admission control. For delay-insensitive data, finite buffer is used to minimize cell loss probability, while keeping the average delayunder a maximum value. First, a broadband multiservice multiplexer is studied, and approximations for performance measures (call blocking probability, cell average delay and loss probability) are derived. Moreover, some results are gerneralized to multirate loss network (e.g., star network). The resulting estimate is checked with computer simulation which is also used to establish the interaction pattern between individual service QoS and overall system performance.

碩士
國立臺北科技大學
電腦通訊與控制研究所
89
Toward the goal of prospective anytime, anywhere, and seamless communications, integrating terrestrial communications with satellite systems that provide a global coverage will be an indispensable solution. Among various satellite system deployments, the Low-Earth Orbit (LEO) satellite systems possessing low attenuation, low propagation delay, and low cost have received much attention. In virtue of supporting diversified services (multiservice) by future networks is a necessity and that will call for different requirements on transmission bandwidth (multirate), it brings out the cardinal importance of resource allocation, call admission and routing to the performance of a LEO network. This thesis focuses on the issues of establishing a high-performance LEO satellite network. The subjects to be investigated include: the call admission control policy for entering the satellite network, the strategy for transmission resource allocation and resource reservation for handover services, the algorithms for inter-satellite routing, and the methods of link load balancing and rerouting. The theoretical basis applied to this research is Markov Decision Process (MDP). Based upon the MDP theory and related formulation, the thesis is about to evaluate several resource reservation schemes and design a call admission control providing higher resource utilization and resolving the impacts onto by handover calls. In addition, it proposed a suitable cost routing method in contrast to centralized ones such as least cost routing, least-loaded routing and minimum hop routing. The research showed that the suitable cost routing can not only improve systems’ performance, but also reduce connection setup time and ease the implementation.

博士
國立臺灣科技大學
電機工程系
90
The next generation wireless network is expected to support a wide range of services, such as voice, data, and video. As is well known, different services may have very distinct characteristics. For example, the call holding time of data is usually much longer than that of voice, and calls originated from pedestrians and vehicles may have different mobility. One call with longer call holding time and/or fast mobility on average leads to more handoff requests during its lifetime. Frequent handoff requests may give a serious impact on quality of service. Thus, it is necessary to take account of call holding time and mobility difference among different services to design a call admission control (CAC) scheme applied to wireless networks. To improve the resource efficiency and maintain new call blocking probability and forced termination probability at an acceptable level, the concept of acceptance probability is introduced for regulating the acceptance of new calls. With the knowledge of system parameters, e.g., call holding time and mobility, knowledge-based CAC schemes are proposed for the following scenarios: one-tier networks with single rate service, one-tier wireless ATM networks with multiple CBR, ABR and UBR services, and two-tier cellular networks with voice and data calls. Analytical methods as well as computer simulations are developed for the studied scenarios to obtain the performance measures of interest. Importantly, the analytical results are close to the corresponding simulation results. Also, numerical results are shown to illustrate the robustness of the proposed schemes. Last but not least, the performance evaluation of hierarchical cellular networks with multirate traffic is conducted. An efficient and reasonably accurate analytical model for overflowed traffic is developed to evaluate performance measures of interest.

碩士
國立臺灣科技大學
電機工程系
91
The future wireless network is expected to support a wide range of services, such as voice and data. Different services may have different characteristics. For example, the average holding time of voice calls is 3 minutes, whereas that of data calls may be as long as 30 minutes. In order to be more realistic, we consider multiservice cellular systems with a finite number of cells, finite population and non-uniform traffic, where the transition probabilities may change from cell to cell. As is well known, compared to FCA (Fixed Channel Allocation), DCA (Dynamic Channel Allocation) can achieve higher efficiency at the expense of higher system complexity and overhead. We consider both FCA and DCA for comparison. Furthermore, to make the analysis of DCA tractable mathematically, DCA with MP (maximum packing) is assumed, where MP means all necessary rearrangements will be performed in order to accommodate a call. It is generally believed that, compared to new call blockings, an ongoing call being forcefully terminated is less tolerable by the users. Thus, some of all the useable channels, so-called guard channels, are reserved exclusively for handoff calls. With channels reserved for handoff calls, the new call blocking probability may be very different from handoff failure probability. We develop a cost function to evaluate the overall system performance by giving different weights to new call blocking probability and handoff failure probability. The performance measures of interest are computed with a two-phase approximation method, where in the first phase the average number of subscribers in each cell is derived based on closed queueing network model, and in the second phase the steady state probabilities are found via a two-dimensional Markov process iteratively. A simulation program is written in C language to verify the accuracy of analytical results.

碩士
國立臺灣科技大學
電機工程系
91
Due to the diversity of communication needs, the next generation wireless network is expected to support a wide range of services, such as voice, data, and video. As is well known, different services may have very distinct characteristics. For example, the call holding time of data is usually much longer than that voice. One call with longer call holding time on average leads to more handoff requests during its lifetime. Frequent handoff requests may give a serious impact on quality of service (QoS). Call admission control (CAC) is one of the key elements to provide quality of service guarantee in wireless mobile networks. In general, compared to new call blockings, forced termination of ongoing calls due to handoff blocking is less tolerable. We give a higher access priority to handoff requests over new calls by reserving them resources. We propose a call admission control scheme to provide dynamic adaptive prioritized admission of different traffic classes. The scheme adapts the number of guard channels in each cell according to the estimate of the handoff call arrival rate computed from the number of ongoing calls in neighboring cells and the mobility pattern, in order to maintain the handoff failure probability at the target objective while minimizing the degradation to the new call blocking probability. In order to make the system model more realistic, we adopt a multi-cell configuration, where cells may have different mobility pattern and the number of cells is finite. We assume the transit probability of a mobile station from one cell to another cell depends on both the cell type and the time of day. We study both stationary and non-stationary scenarios. We write simulation program in C language to obtain performance measures of interest, and we demonstrate the effectiveness of our method by simulations. We study the effect of cell types and time intervals on performance measures. We also compare the proposed dynamic guard channel scheme and the static guard channel scheme. The results show that, overall speaking, our scheme results in better performance.