Magister Scientiae - MSc / Telecommunication companies, service providers and large companies are now adapting converged multi-service Next Generation Networks (NGNs). Network management is shifting from managing Network Elements (NE) to managing services. This paradigm shift coincides with the rapid development of Quality of Service (QoS) protocols for IP networks. NEs and services are managed with Policy Based Network Management (PBNM) which is most concerned with managing services that require QoS using the Common Open Policy Service (COPS) Protocol. These services include Voice over IP (VoIP), video conferencing and video streaming. It follows that legacy NEs without support for QoS need to be replaced and/or excluded from the network. However, since most of these services run over IP, and legacy NEs easily supports IP, it may be unnecessary to throw away legacy NEs if it can be made to fit within a PBNM approach. Our approach enables an existing PBNM system to include legacy NEs in its management paradigm. The Proxy-Policy Enforcement Point (P-PEP) and Queuing Policy Enforcement Point (Q-PEP) can enforce some degree of traffic shaping on a gateway to the legacy portion of the network. The P-PEP utilises firewall techniques using the common legacy and contemporary NE management protocol Simple Network Management Protocol (SNMP) while the Q-PEP uses queuing techniques in the form Class Based Queuing (CBQ) and Random Early Discard (RED) for traffic control. / South Africa

The Datagram Congestion Control Protocol (DCCP) is a prominent transport protocol that has attracted the attention of the scientific community for its rapid progress and good results. The main novelty of DCCP is the performance priority design, as in UDP, however with congestion control capabilities, as in TCP. Literature about DCCP is still scarce and needs to be complemented to gather enouth scientific elements to support new research properly. In this context, this work joins the efforts of the scientific community to analise, mensure, compare and characterize DCCP in relevant scenarios that cover many real world situations. Three open questions were preliminarly identified in the literature: How DCCP behaves (i) when fighting for the same link bandwidth with other transport protocols; (ii) with highly relevant ones (e.g., Compound TCP, CUBIC) and (iii) fighting for the same link bandwidth with Compound TCP and CUBIC, adopting multimedia applications (e.g., VoIP). In this work, computational simulations are used to compare the performance of two DCCP variants (DCCP CCID2 and DCCP CCID3) with three highly representative TCP variants (Compound TCP, CUBIC and TCP SACK), in real world scenarios, including concurrent use of the same link by protocols, link errors and assorted bandwidths, latencies and traffic patterns. The simulation results show that, under contention, in most scenarios DCCP CCID2 has achieved higher throughput than Compound TCP or TCP SACK. Throughout the simulations there was a tendency of DCCP CCID3 to have lower throughput than the other chosen protocol. However, the results also showed that DCCP CCID3 has achieved significanly better throughput in the presence of link errors and higher values of latency and bandwidth, eventualy outperforming Compound TCP and TCP SACK. Finally, there was a tendency of predominance of CUBIC´ throughtput, which can be explained by its aggressive algorithm (i.e., non-linear) of return of the transmission window to the previous value before the discard event. However, CUBIC has presented the highest packet drop and the lowest delivery rate. / O Datagram Congestion Control Protocol (DCCP) é um proeminente protocolo de transporte que vem atraindo a atenção da comunidade científica pelos seus rápidos avanços e bons resultados. A principal inovação do DCCP é a priorização de desempenho, como ocorre com o UDP, mas com capacidade de realizar controle de congestionamento, como ocorre com o TCP. Entretanto, a literatura sobre o DCCP ainda é escassa e necessita ser complementada para trazer elementos científicos suficientes para novas pesquisas. Neste contexto, este trabalho vem se somar aos esforços da comunidade científica para analisar, mensurar, comparar e caracterizar o DCCP em cenários representativos que incorporem diversas situações de uso. Identificaram-se então três questões alvo, ainda em aberto na literatura: qual é o comportamento do DCCP (i) quando disputa o mesmo enlace com outros protocolos de transporte; (ii) com protocolos de transporte relevantes (e.g., Compound TCP, CUBIC) e (iii) em disputa no mesmo enlace com o Compound TCP e o CUBIC, utilizando aplicações multimídia (e.g., VoIP). Neste trabalho, simulações computacionais são utilizadas para comparar duas variantes do DCCP (CCID2 e CCID3) a três variantes do TCP (Compound TCP, CUBIC e TCP SACK), em cenários onde ocorrem situações de mundo real, incluindo utilização concorrente do enlace pelos protocolos, presença de erros de transmissão no enlace, variação de largura de banda, variação de latência, e variação de padrão e distribuição de tráfego. Os resultados das simulações apontam que, sob contenção, na maioria dos cenários o DCCP CCID2 obteve vazão superior à do Compound TCP, do DCCP CCID3 e do TCP SACK. Ao longo das simulações observou-se uma tendência do DCCP CCID3 a ter vazão inferior à dos demais protocolos escolhidos. Entretanto, os resultados apontaram que o DCCP CCID3 obteve desempenho significativamente melhor na presença de erros de transmissão e com valores maiores de latência e de largura de banda, chegando a ultrapassar a vazão do DCCP CCID2 e do TCP SACK. Por fim, observou-se uma tendência de predominância do protocolo CUBIC no tocante à vazão, que pode ser determinada pelo seu algoritmo agressivo (i.e., não-linear) de retorno da janela de transmissão ao valor anterior aos eventos de descarte. Entretanto, o CUBIC apresentou o maior descarte de pacotes e a menor taxa de entrega.

Made available in DSpace on 2015-04-11T14:03:03Z (GMT). No. of bitstreams: 1 Fuad M Abinader Junior.pdf: 1012469 bytes, checksum: 83006b70c65e7b5ac0b070b259981f64 (MD5) Previous issue date: 2006-04-13 / The current wireless networks development scenario indicates that mobile VoIP applications are increasing their appeal among consumers, which creates an increasing demand for bandwidth consuption. However, bandwidth availability for VoIP applications is restricted by phisical and regulatory means. Header compression algorithms are one of the most used bandwidth optimization techniques for VoIP applications in wireless networks. This dissertation presents a performance evaluation of cooperative header compression algoritms for VoIP applications in wireless networks. The results indicate that the use of the single-channel cooperative approach leads to excelent results in terms of bandwidth optimization alied with robust context update. Also, the results indicate that the multi-channel cooperative approach has serious issues regarding parallel asyncrhonous VoIP connections. / O cenário atual do desenvolvimento das redes sem fio indica que o apelo por aplicações VoIP móveis está crescendo entre os consumidores, o que gera uma demanda cada vez maior de consumo de largura de banda. No entanto, a disponibilidade de largura de banda para aplicações VoIP é limitada tanto pelo meio físico quanto por regulamentações governamentais. O uso de algoritmos de compressão de cabeçalho é uma das técnicas mais usadas para otimização de largura de banda para aplicações VoIP em redes sem fio. Esta dissertação apresenta uma avaliação de desempenho de algoritmos de compressão de cabeçalhos cooperativos para aplicações VoIP em redes sem fio. Os resultados indicam que a utilização do algoritmo cooperativo mono-canal leva a excelentes resultados em termos de otimização de largura de banda com a manutenção das atualizações de contexto. Além disso, os resultados indicam que o uso do algoritmo cooperativo multi-canal possui sérias restrições quando utilizado em conjunto com conexões VoIP paralelas e assíncronas.

Made available in DSpace on 2016-08-17T14:52:53Z (GMT). No. of bitstreams: 1 Ricardo Henrique Bezerra Azoubel.pdf: 588389 bytes, checksum: 40c0c99f808c27d0a6967b9d18c9c22a (MD5) Previous issue date: 2004-09-24 / This work presents a platform of tests (testbed) inexpensive, constructed in a controlled environment composed by microcomputers and free softwares. It is implemented, in such platform, the differentiated service model (DiffServ), with expedited forwarding (PHB EF). It is basically considered, from the collection of metrics main of QoS (delay, jitter, loss and throughtput), the performance analysis of voice characteristic traffics, when submitted to experimental tests in some scenes and conditions. Initially, in an environment capable to differentiate traffics, flows generated by standardized voice coder/decoder (G.711 and G.726) are modeled, in which the packets size and the amount of aggregate flows are varied, in scenes with and without QoS. It is compared, after that, the behavior of flows generated by activity-silence (ON-OFF) and continuous (CBR) sources. Can be perceived in this study how much the packets size variation influence in the performance of the most priority packets. It is carried, in the sequence, a specific analysis of the aggregation factor in flows generated by ON-OFF sources, in which can be observed the action of the basic principle of the model DiffServ, where aggregate flows receive differentiated treatment. It is studied, finally, through the use of transport protocols (UDP and TCP) and of elastic flows of FTP type, how much the best effort traffic confuses the performance of voice modeled flows. / Este trabalho apresenta uma plataforma de testes (testbed) sem custos, construída num ambiente controlado composto por microcomputadores e softwares livres. Implementa-se, em tal plataforma, o modelo de serviço diferenciado (DiffServ), com encaminhamento expresso (PHB EF). Propõe-se, fundamentalmente, a partir da obtenção das principais métricas de QoS (atraso, jitter, perda e vazão), a análise do desempenho de tráfego característico de voz, quando submetido a testes experimentais em vários cenários e condições. Inicialmente, num ambiente capaz de diferenciar tráfego, modelam-se fluxos gerados por codificadores/decodificadores de voz padronizados (G.711 e G.726), em que se varia o tamanho dos pacotes e a quantidade de fluxos agregados, em cenários com e sem QoS. Compara-se, em seguida, o comportamento de fluxos gerados por fontes atividadesilêncio (ON-OFF) e contínuas (CBR). Pode-se perceber nesse estudo o quanto a variação do tamanho dos pacotes impacta no desempenho dos pacotes mais prioritários. Realiza-se, na seqüência, uma análise específica do fator agregação em fluxos gerados por fontes ONOFF e observa-se a atuação do princípio básico do modelo DiffServ, onde fluxos agregados recebem tratamento diferenciado. Estuda-se, por fim, através da utilização de protocolos de transporte (UDP e TCP) e de fluxos elásticos do tipo FTP, o quanto o tráfego de melhor esforço impacta no desempenho de fluxos modelados de voz.

A dissertação investiga possibilidades formais de articulação entre universos pessoais e processos históricos no campo da realização documentária em primeira pessoa. O ponto de partida são materiais e procedimentos advindos de um documentário de longa-metragem que atualmente desenvolvo, intitulado Bem vindos de novo. O filme aborda as experiências da minha família na imigração de nipo-brasileiros para o Japão, conhecida como \"fenômeno decasségui\". Nele, busco articular as experiências pessoais e familiares com aspectos mais amplos desse acontecimento histórico e social, de proporções internacionais, que atingiu, e continua afetando diretamente, cerca de 600 mil pessoas. Abordo três procedimentos formais empregados no filme: (1) a utilização de fotografias domésticas; (2) a elaboração da narração em voz over; (3) o emprego de filmagens históricas realizadas por Hikoma Udihara, colonizador e cinegrafista pioneiro da imigração japonesa no Brasil. Através do mapeamento de possibilidades formais relacionadas aos procedimentos em questão, busco identificar e analisar um conjunto de conceitos, de instrumentos críticos e teóricos, úteis para se pensar a articulação entre o íntimo e o histórico, o pessoal e o social, em documentários na primeira pessoa; em diálogo constante com aspectos concretos da realização cinematográfica. / This master\'s thesis investigates formal possibilities of articulation between personal universes and historical processes inside the first person filmmaking practice. The bases are materials and procedures related to a feature documentary film that I am now developing, called Welcome Back, Farewell (Bem vindos de novo). The film addresses my family experiences in immigration of Japanese-Brazilians to Japan, known as \"dekassegui phenomenon\". In the film, I try to articulate personal and familiar experiences with wider features of this historical and social event of international proportion, which reached, and still concerns directly to six hundreds thousand people. Three formal procedures of the film are covered: (1) the use of domestic photography; (2) the elaboration of the voice over narration; (3) the usage of historical footage produced by Hikoma Udihara, colonizer and pioneer amateur filmmaker of the Japanese immigration in Brazil. Through the organization of formal possibilities related with the previous procedures, the aim is to identify and analyze a group of concepts, of critical and theoretical devices, useful to think the articulation between the intimate and the historical, the personal and the social, within the first person documentary; in frequent contact with concrete features of the filmmaking practice.

Multiprotocol Label Switching (MPLS) is a new paradigm in routing architectures which has changed the way Internet Protocol (IP) packet is transferred in a Network. MPLS ensures the reliability of the communication minimizing the delays and enhancing the speed of packet transfer. One important feature of MPLS is its capability of providing Traffic Engineering (TE) which plays a vital role for minimizing the congestion by efficient load, balancing and management of the network resources. The performance evaluation is done considering the network parameters latency, jitter, packet end to end delay, and packet delay variation. Integration of QoS with the MPLS-TE network may enhance the performance of the network. Various scheduling algorithms can be used for implementing QoS on a network, which may vary the performance of the network. In our study, QoS is implemented on top of the MPLS-TE network using Differentiated Service (DiffServ) architecture. Different basic scheduling algorithms are used for the implementation of QoS and to check their impact on the network and to identify the suitable one among them. Performance evaluation is done considering the network parameters latency, jitter, packet end-to-end delay, and Packet Delay Variation. The simulation was done using OPNET modeler 16.0 and the results were analyzed. The simulation result shows that using TE along with QoS in MPLS network decreases the latency, jitter, packet delay variation and end to end packet delay compared to using TE alone for voice traffic. / +46738732963

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Multiprotocol Label Switching (MPLS) is an emerging technology which ensures the reliable delivery of the Internet services with high transmission speed and lower delays. The key feature of MPLS is its Traffic Engineering (TE), which is used for effectively managing the networks for efficient utilization of network resources. Due to lower network delay, efficient forwarding mechanism, scalability and predictable performance of the services provided by MPLS technology makes it more suitable for implementing real-time applications such as voice and video. In this thesis performance of Voice over Internet Protocol (VoIP) application is compared between MPLS network and conventional Internet Protocol (IP) network. OPNET modeler 14.5 is used to simulate the both networks and the comparison is made based on some performance metrics such as voice jitter, voice packet end-to-end delay, voice delay variation, voice packet sent and received. The simulation results are analyzed and it shows that MPLS based solution provides better performance in implementing the VoIP application. In this thesis, by using voice packet end-to-end delay performance metric an approach is made to estimate the minimum number of VoIP calls that can be maintained, in MPLS and conventional IP networks with acceptable quality. This approach can help the network operators or designers to determine the number of VoIP calls that can be maintained for a given network by imitating the real network on the OPNET simulator. / 0046737675303

With the constant development of wireless technologies, the usageof wireless devices tends to increase even more in the future.Wireless multi-hop networks (WMNs) have emerged as a keytechnology to numerous potential scenarios, ranging from disasterrecovery to wireless broadband internet access. The distributedarchitecture of WMNs enables nodes to cooperatively relay othernode's packets. Because of their advantages over other wirelessnetworks, WMNs are undergoing rapid progress and inspiringnumerous applications. However, many technical issues still existin this field. In this thesis we investigate how Voice over IP(VoIP) and peer-to-peer (P2P) application are influenced bywireless multi-hop network characteristics and how to optimizethem in order to provide scalable communication.We first consider the deployment of VoIP service in wirelessmulti-hop networks, by using the Session Initiation Protocol (SIP)architecture. Our investigation shows that the centralized SIParchitecture imposes several challenges when deployed in thedecentralized wireless multi-hop environment. We find that VoIPquality metrics are severely degraded as the traffic and number ofmultiple hops to the gateway increase. In the context ofscalability, we further propose four alternative approaches whichavoid current limitations.In the second part of this thesis we tackle the network capacityproblem while providing scalable VoIP service over wirelessmulti-hop networks. The performance evaluation shows the influenceof intra and inter-flow interference in channel utilization, whichdirect impacts the VoIP capacity. In order to avoid the small VoIPpacket overhead, we propose a new adaptive hop-by-hop packetaggregation scheme based on wireless link characteristics. Ourperformance evaluation shows that the proposed scheme can increasethe VoIP capacity by a two-fold gain.The study of peer-to-peer applicability over wireless multi-hopnetworks is another important contribution. A resource lookupapplication is realized through structured P2P overlay. We showthat due to several reasons, such as characteristics of wirelesslinks, multi-hop forwarding operation, and structured P2Pmanagement traffic aggressiveness the performance of traditionalP2P applications is rather low in wireless multi-hop environments.Therefore, we suggested that a trade-off between the P2P lookupefficiency and the P2P management traffic overhead can be achievedwhile maintaining the overlay network consistency in wirelessmulti-hop networks.

Voices and Silences: Exploring English and French Versions at the National Film Board of Canada, 1939-1974 Abstract The National Film Board of Canada (NFB) is unique as a state-sponsored filmmaking institution for its bilingualism: it has consistently produced and distributed films in English and French and made versions of some of those films in the opposite language. This doctoral thesis fills a gap in existing literature on the NFB and in translation studies by taking the versions as its object of study. The corpus is drawn from the vast body of audiovisual productions made by the NFB between 1939 and 1974, when voice-over was the preferred mode of audiovisual translation. Voice-over can refer to either the translated narration that replaces the original voice of narration-led documentaries, or to the audiovisual voice-over of documentaries built around interviews and spontaneous speech. Against the backdrop of asymmetrical language relations between English and French in Canada, this thesis offers a retelling of the NFB’s early history that emphasizes the intertwining threads of English and French production and identifies several approaches to version making. From 1939 to the mid-1950s, with English-language production dominant at the NFB and little original production in French, versions from English to French were a central element of film in Quebec. They bear witness to an interventionist approach to translating, whereby the original film is treated as raw material that can be shaped to appeal to local audiences. Subsequently, an increase in French original production, reflecting changing documentary aesthetics and growing nationalism in Quebec, led to a correspondingly higher number of French-to-English versions. These versions adopted a mediating approach by adding a narrator’s voice in English to originals that eschewed narration, bringing the innovative French films into conformity with the traditional model. The period from 1967 to 1974 is one of fragmentation and is characterized by a high level of non-translation, whether of the Challenge for Change/Société nouvelle films or those of Studio D. The few films that were versioned, however, showed great sensitivity to language. Non-translation of a different kind can be found in many Aboriginal films produced at the NFB. The NFB’s long-standing commitment to translation makes it a valuable site for studying audiovisual translation practices and changing language relations in Canada. Voix et silences : Une exploration des versions anglaises et françaises produites par l’Office national du film du Canada, 1939-1974 Résumé L’Office national du film du Canada (ONF), institution financée par l’État pour la création d’œuvres cinématographiques, se distingue par son bilinguisme, car il a toujours produit et distribué ses films en anglais ou en français tout en prenant soin de fournir une version dans la langue opposée. La thèse se penche sur ces versions et vient combler un vide dans les recherches sur l’ONF ainsi qu’en traductologie. Le corpus à l’étude provient d’une vaste production audiovisuelle réalisée entre 1939 et 1974, époque où le mode de traduction privilégié des documentaires était la voix hors-champ. Ce terme désigne autant la narration traduite qui remplace la voix originale que la voix en surimposition utilisée pour les entrevues et le discours spontané. La thèse relate les débuts de l’ONF dans le contexte des relations asymétriques entre l’anglais et le français au Canada et porte un regard neuf sur les liens entre les studios anglophones et francophones en plus de décrire certaines tendances dans la production de versions. De 1939 jusqu’au milieu des années 1950, lorsque l’anglais dominait, par rapport aux rares films produits originalement en français, les versions françaises traduites de l’anglais contribuèrent substantiellement à la cinématographie québécoise. Elles témoignent d’une stratégie de traduction interventionniste, par laquelle le film original est considéré comme une matière première que l’on peut manipuler afin d’accrocher le public local. Par suite d’un changement dans l’esthétique du documentaire et de la montée du nationalisme québécois, les originaux en langue française s’accrurent et entraînèrent une augmentation des versions du français à l’anglais. Celles-ci usèrent d’un mode de médiation qui consistait à rajouter une voix narrative anglophone aux films novateurs en français, du fait qu’ils avaient évacué la narration, soumettant ainsi les créations originales au modèle traditionnel. La période de 1967 à 1974 en est une de fragmentation se caractérisant par un nombre élevé de films non traduits, tels que ceux produits dans le cadre du programme Challenge for Change/Société nouvelle ou par le Studio D. Les quelques productions qui furent traduites, cependant, connurent des versions d’une grande sensibilité linguistique. Un phénomène de non-traduction, mais d’un autre ordre, s’observe par ailleurs dans certains films autochtones. Depuis longtemps, l’ONF s’est engagé à traduire ses productions; c’est ce qui en fait un site riche pour l’étude des pratiques de la traduction audiovisuelle et du changement des relations entre les langues au Canada.