Rendezvous Point Selection In Multicast Networks

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2005Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2005Bu çalışmada, günümüzde kullanılan seyrek tarzlı çoklu aktarım algoritmalarının bir eksiği olan ve dinamik üyelere sahip çoklu aktarım gruplarında daha belirgin olarak gözlemlenen çoklu gönderim ağacına bağlı servis kalitesinde düşme problemi üzerinde durulmaktadır. Günümüzde kullanılan seyrek tarzlı çoklu gönderim algoritmalarında, merkez düğüm seçilmesi yönetimsel olarak yapılmaktadır ve durağan bir seçim yöntemidir. Bu nedenle, zamanla çoklu aktarım grubuna yeni alıcılar ve kaynaklar üye olduklarında ya da ayrıldıklarında, yönetimsel olarak seçilen merkez düğümlü çoklu aktarım ağaçlarında servis kalitesi düşer. Beklenen servis kalitesine tekrar ulaşabilmek için, yeni bir merkez düğüm seçilmeli ve çoklu gönderim ağacı yeni bulunan merkez düğüme göre oluşturulmalıdır. Bu çalışmada, var olan protokollerden PIM-SM çoklu gönderim protokolü ile merkez düğümün dinamik değişmesine olanak veren SCMP çoklu gönderim protokolü incelenmiş, birbirleriyle karşılaştırılmış ve merkez düğümün yer değiştirilmesinin sağladığı avantajlar ve dezavantajlar farklı tipteki ağlar ve çoklu aktarım senaryoları üzerinde denenerek belirlenmeye çalışılmıştır. Ayrıca, yapılan bu çalışma sırasında esnek bir çoklu gönderim senaryo üreteci geliştirilmiştir.In this study, the focus is on the problem of the degradation of the multicast trees used in sparse mode multicast protocols, which have dynamic members, due to inefficiency in the location of the core (rendezvous) router as time proceeds. In sparse mode multicast protocols, the rendezvous point is chosen administratively and it is a static selection method unresponsive to the changes in the network dynamics. Therefore, when new sources or receivers join/leave the multicast group by time, the quality of service(QoS) provided by the multicast tree degrades. A better rendezvous point should be selected to prevent this problem and a new multicast tree must be reconstructed rooted at the new RP. In this study, PIM-SM protocol,with static RP, is compared with SCMP protocol which enables the RP to be changed. The advantages and the disadvantages of dynamic RP relocation process is investigated for different type of networks and multicast scenarios. During this work, a flexible multicast scenario generator is developed and used.Yüksek LisansM.Sc

Distribuição de vídeo para grupos de utilizadores em redes móveis heterogéneas19

The evolutions veri ed in mobile devices capabilities (storage capacity, screen resolution, processor, etc.) over the last years led to a signi cant change in mobile user behavior, with the consumption and creation of multimedia content becoming more common, in particular video tra c. Consequently, mobile operator networks, despite being the target of architectural evolutions and improvements over several parameters (such as capacity, transmission and reception performance, amongst others), also increasingly become more frequently challenged by performance aspects associated to the nature of video tra c, whether by the demanding requirements associated to that service, or by its volume increase in such networks. This Thesis proposes modi cations to the mobile architecture towards a more e cient video broadcasting, de ning and developing mechanisms applicable to the network, or to the mobile terminal. Particularly, heterogeneous networks multicast IP mobility supported scenarios are focused, emphasizing their application over di erent access technologies. The suggested changes are applicable to mobile or static user scenarios, whether it performs the role of receiver or source of the video tra c. Similarly, the de ned mechanisms propose solutions targeting operators with di erent video broadcasting goals, or whose networks have di erent characteristics. The pursued methodology combined an experimental evaluation executed over physical testbeds, with the mathematical evaluation using network simulation, allowing the veri cation of its impact on the optimization of video reception in mobile terminalsA evolução veri cada nas características dos dispositivos moveis (capacidade de armazenamento, resolução do ecrã, processador, etc.) durante os últimos anos levou a uma alteração signi cativa nos comportamentos dos utilizadores, sendo agora comum o consumo e produção de conteúdos multimédia envolvendo terminais móveis, em particular o tráfego vídeo. Consequentemente, as redes de operador móvel, embora tendo também sido alvo constante de evoluções arquitecturais e melhorias em vários parâmetros (tais como capacidade, ritmo de transmissão/recepção, entre outros), vêemse cada vez mais frequentemente desa adas por aspectos de desempenho associados à natureza do tráfego de vídeo, seja pela exigência de requisitos associados a esse serviço, quer pelo aumento do volume do mesmo nesse tipo de redes. Esta Tese propôe alterações à arquitetura móvel para a disseminação de vídeo mais e ciente, de nindo e desenvolvendo mecanismos aplicáveis à rede, ou ao utilizador móvel. Em particular, são focados cenários suportados por IP multicast em redes móveis heterogéneas, isto é, com ênfase na aplicação destes mecanismos sobre diferentes tecnologias de acesso. As alterações sugeridas aplicam-se a cenários de utilizador estático ou móvel, sendo este a fonte ou receptor do tráfego vídeo. Da mesma forma, são propostas soluções tendo em vista operadores com diferentes objectivos de disseminação de vídeo, ou cujas redes têm diferentes características. A metodologia utilizada combinou a avaliação experimental em testbeds físicas com a avaliação matemática em simulações de redes, e permitiu veri car o impacto sobre a optimização da recepção de vídeo em terminais móveisPrograma Doutoral em Telecomunicaçõe

Esquema de controlo para redes multicast baseadas com classes

Doutoramento em Engenharia ElectrotécnicaThe expectations of citizens from the Information Technologies (ITs) are increasing as the ITs have become integral part of our society, serving all kinds of activities whether professional, leisure, safety-critical applications or business. Hence, the limitations of the traditional network designs to provide innovative and enhanced services and applications motivated a consensus to integrate all services over packet switching infrastructures, using the Internet Protocol, so as to leverage flexible control and economical benefits in the Next Generation Networks (NGNs). However, the Internet is not capable of treating services differently while each service has its own requirements (e.g., Quality of Service - QoS). Therefore, the need for more evolved forms of communications has driven to radical changes of architectural and layering designs which demand appropriate solutions for service admission and network resources control. This Thesis addresses QoS and network control issues, aiming to improve overall control performance in current and future networks which classify services into classes. The Thesis is divided into three parts. In the first part, we propose two resource over-reservation algorithms, a Class-based bandwidth Over-Reservation (COR) and an Enhanced COR (ECOR). The over-reservation means reserving more bandwidth than a Class of Service (CoS) needs, so the QoS reservation signalling rate is reduced. COR and ECOR allow for dynamically defining over-reservation parameters for CoSs based on network interfaces resource conditions; they aim to reduce QoS signalling and related overhead without incurring CoS starvation or waste of bandwidth. ECOR differs from COR by allowing for optimizing control overhead minimization. Further, we propose a centralized control mechanism called Advanced Centralization Architecture (ACA), that uses a single state-full Control Decision Point (CDP) which maintains a good view of its underlying network topology and the related links resource statistics on real-time basis to control the overall network. It is very important to mention that, in this Thesis, we use multicast trees as the basis for session transport, not only for group communication purposes, but mainly to pin packets of a session mapped to a tree to follow the desired tree. Our simulation results prove a drastic reduction of QoS control signalling and the related overhead without QoS violation or waste of resources. Besides, we provide a generic-purpose analytical model to assess the impact of various parameters (e.g., link capacity, session dynamics, etc.) that generally challenge resource overprovisioning control. In the second part of this Thesis, we propose a decentralization control mechanism called Advanced Class-based resource OverpRovisioning (ACOR), that aims to achieve better scalability than the ACA approach. ACOR enables multiple CDPs, distributed at network edge, to cooperate and exchange appropriate control data (e.g., trees and bandwidth usage information) such that each CDP is able to maintain a good knowledge of the network topology and the related links resource statistics on real-time basis. From scalability perspective, ACOR cooperation is selective, meaning that control information is exchanged dynamically among only the CDPs which are concerned (correlated). Moreover, the synchronization is carried out through our proposed concept of Virtual Over-Provisioned Resource (VOPR), which is a share of over-reservations of each interface to each tree that uses the interface. Thus, each CDP can process several session requests over a tree without requiring synchronization between the correlated CDPs as long as the VOPR of the tree is not exhausted. Analytical and simulation results demonstrate that aggregate over-reservation control in decentralized scenarios keep low signalling without QoS violations or waste of resources. We also introduced a control signalling protocol called ACOR Protocol (ACOR-P) to support the centralization and decentralization designs in this Thesis. Further, we propose an Extended ACOR (E-ACOR) which aggregates the VOPR of all trees that originate at the same CDP, and more session requests can be processed without synchronization when compared with ACOR. In addition, E-ACOR introduces a mechanism to efficiently track network congestion information to prevent unnecessary synchronization during congestion time when VOPRs would exhaust upon every session request. The performance evaluation through analytical and simulation results proves the superiority of E-ACOR in minimizing overall control signalling overhead while keeping all advantages of ACOR, that is, without incurring QoS violations or waste of resources. The last part of this Thesis includes the Survivable ACOR (SACOR) proposal to support stable operations of the QoS and network control mechanisms in case of failures and recoveries (e.g., of links and nodes). The performance results show flexible survivability characterized by fast convergence time and differentiation of traffic re-routing under efficient resource utilization i.e. without wasting bandwidth. In summary, the QoS and architectural control mechanisms proposed in this Thesis provide efficient and scalable support for network control key sub-systems (e.g., QoS and resource control, traffic engineering, multicasting, etc.), and thus allow for optimizing network overall control performance.À medida que as Tecnologias de Informação (TIs) se tornaram parte integrante da nossa sociedade, a expectativa dos cidadãos relativamente ao uso desses serviços também demonstrou um aumento, seja no âmbito das atividades profissionais, de lazer, aplicações de segurança crítica ou negócios. Portanto, as limitações dos projetos de rede tradicionais quanto ao fornecimento de serviços inovadores e aplicações avançadas motivaram um consenso quanto à integração de todos os serviços e infra-estruturas de comutação de pacotes, utilizando o IP, de modo a extrair benefícios económicos e um controlo mais flexível nas Redes de Nova Geração (RNG). Entretanto, tendo em vista que a Internet não apresenta capacidade de diferenciação de serviços, e sabendo que cada serviço apresenta as suas necessidades próprias, como por exemplo, a Qualidade de Serviço - QoS, a necessidade de formas mais evoluídas de comunicação tem-se tornado cada vez mais visível, levando a mudanças radicais na arquitectura das redes, que exigem soluções adequadas para a admissão de serviços e controlo de recursos de rede. Sendo assim, este trabalho aborda questões de controlo de QoS e rede com o objetivo de melhorar o desempenho do controlo de recursos total em redes atuais e futuras, através da análise dos serviços de acordo com as suas classes de serviço. Esta Tese encontra-se dividida em três partes. Na primeira parte são propostos dois algoritmos de sobre-reserva, o Class-based bandwidth Over-Reservation (COR) e uma extensão melhorada do COR denominado de Enhanced COR (ECOR). A sobre-reserva significa a reserva de uma largura de banda maior para o serviço em questão do que uma classe de serviço (CoS) necessita e, portanto, a quantidade de sinalização para reserva de recursos é reduzida. COR e ECOR consideram uma definição dinâmica de sobre-reserva de parâmetros para CoSs com base nas condições da rede, com vista à redução da sobrecarga de sinalização em QoS sem que ocorra desperdício de largura de banda. O ECOR, por sua vez, difere do COR por permitir a otimização com minimização de controlo de overhead. Além disso, nesta Tese é proposto também um mecanismo de controlo centralizado chamado Advanced Centralization Architecture (ACA) , usando um único Ponto de Controlo de Decisão (CDP) que mantém uma visão ampla da topologia de rede e de análise dos recursos ocupados em tempo real como base de controlo para a rede global. Nesta Tese são utilizadas árvores multicast como base para o transporte de sessão, não só para fins de comunicação em grupo, mas principalmente para que os pacotes que pertençam a uma sessão que é mapeada numa determinada árvore sigam o seu caminho. Os resultados obtidos nas simulações dos mecanismos mostram uma redução significativa da sobrecarga da sinalização de controlo, sem a violação dos requisitos de QoS ou desperdício de recursos. Além disso, foi proposto um modelo analítico no sentido de avaliar o impacto provocado por diversos parâmetros (como por exemplo, a capacidade da ligação, a dinâmica das sessões, etc), no sobre-provisionamento dos recursos. Na segunda parte desta tese propôe-se um mecanismo para controlo descentralizado de recursos denominado de Advanced Class-based resource OverprRovisioning (ACOR), que permite obter uma melhor escalabilidade do que o obtido pelo ACA. O ACOR permite que os pontos de decisão e controlo da rede, os CDPs, sejam distribuídos na periferia da rede, cooperem entre si, através da troca de dados e controlo adequados (por exemplo, localização das árvores e informações sobre o uso da largura de banda), de tal forma que cada CDP seja capaz de manter um bom conhecimento da topologia da rede, bem como das suas ligações. Do ponto de vista de escalabilidade, a cooperação do ACOR é seletiva, o que significa que as informações de controlo são trocadas de forma dinâmica apenas entre os CDPs analisados. Além disso, a sincronização é feita através do conceito proposto de Recursos Virtuais Sobre-Provisionado (VOPR), que partilha as reservas de cada interface para cada árvore que usa a interface. Assim, cada CDP pode processar pedidos de sessão numa ou mais árvores, sem a necessidade de sincronização entre os CDPs correlacionados, enquanto o VOPR da árvore não estiver esgotado. Os resultados analíticos e de simulação demonstram que o controlo de sobre-reserva é agregado em cenários descentralizados, mantendo a sinalização de QoS baixa sem perda de largura de banda. Também é desenvolvido um protocolo de controlo de sinalização chamado ACOR Protocol (ACOR-P) para suportar as arquitecturas de centralização e descentralização deste trabalho. O ACOR Estendido (E-ACOR) agrega a VOPR de todas as árvores que se originam no mesmo CDP, e mais pedidos de sessão podem ser processados sem a necessidade de sincronização quando comparado com ACOR. Além disso, E-ACOR introduz um mecanismo para controlar as informações àcerca do congestionamento da rede, e impede a sincronização desnecessária durante o tempo de congestionamento quando os VOPRs esgotam consoante cada pedido de sessão. A avaliação de desempenho, através de resultados analíticos e de simulação, mostra a superioridade do E-ACOR em minimizar o controlo geral da carga da sinalização, mantendo todas as vantagens do ACOR, sem apresentar violações de QoS ou desperdício de recursos. A última parte desta Tese inclui a proposta para recuperação a falhas, o Survivability ACOR (SACOR), o qual permite ter QoS estável em caso de falhas de ligações e nós. Os resultados de desempenho analisados mostram uma capacidade flexível de sobrevivência caracterizada por um tempo de convergência rápido e diferenciação de tráfego com uma utilização eficiente dos recursos. Em resumo, os mecanismos de controlo de recursos propostos nesta Tese fornecem um suporte eficiente e escalável para controlo da rede, como também para os seus principais sub-sistemas (por exemplo, QoS, controlo de recursos, engenharia de tráfego, multicast, etc) e, assim, permitir a otimização do desempenho da rede a nível do controlo global

Reliable Multicast transport of the video over the WiFi network

Le transport multicast est une solution efficace pour envoyer le même contenu à plusieurs récepteurs en même temps. Ce mode est principalement utilisé pour fournir des flux multimédia en temps réel. Cependant, le multicast classique de l IEEE 802.11 n'utilise aucun mécanisme d acquittement. Ainsi, l échec de réception implique la perte définitive du paquet. Cela limite la fiabilité du transport multicast et impact la qualité des applications vidéo. Pour résoudre ce problème, 802.11v et 802.11aa sont définis récemment. Le premier amendement propose Direct Multicast Service (DMS). D'autre part, le 802.11aa introduit GroupCast with Retries (GCR). GCR définit deux nouvelles politiques de retransmission : Block Ack (BACK) et Unsolicited Retry (UR).Dans cette thèse, nous évaluons et comparons les performances de 802.11v/aa. Nos résultats montrent que tous les nouveaux protocoles multicast génèrent un overhead de transmission important. En outre, DMS a une scalabilité très limitée, et GCR-BACK n'est pas approprié pour des grands groupes multicast. D autre part, nous montrons que DMS et GCR-BACK génèrent des latences de transmission importantes lorsque le nombre de récepteurs augmente. Par ailleurs, nous étudions les facteurs de pertes dans les réseaux sans fil. Nous montrons que l'indisponibilité du récepteur peut être la cause principale des pertes importantes et de leur nature en rafales. En particulier, nos résultats montrent que la surcharge du processeur peut provoquer un taux de perte de 100%, et que le pourcentage de livraison peut être limité à 35% lorsque la carte 802.11 est en mode d économie d'énergie.Pour éviter les collisions et améliorer la fiabilité du transport multicast, nous définissons le mécanisme Busy Symbol (BS). Nos résultats montrent que BS évite les collisions et assure un taux de succès de transmission très important. Afin d'améliorer davantage la fiabilité du trafic multicast, nous définissons un nouveau protocole multicast, appelé Block Negative Acknowledgement (BNAK). Ce protocole opère comme suit. L AP envoi un bloc de paquets suivi par un Block NAK Request (BNR). Le BNR permet aux membres de détecter les données manquantes et d envoyer une demande de retransmission, c.à.d. un Block NAK Response (BNAK). Un BNAK est transmis en utilisant la procédure classique d accès au canal afin d'éviter toute collision avec d'autres paquets. En plus, cette demande est acquittée. Sous l'hypothèse que 1) le récepteur est situé dans la zone de couverture du débit de transmission utilisé, 2) les collisions sont évitées et 3) le terminal a la bonne configuration, très peu de demandes de retransmission sont envoyées, et la bande passante est préservée. Nos résultats montrent que BNAK a une très grande scalabilité et génère des délais très limités. En outre, nous définissons un algorithme d'adaptation de débit pour BNAK. Nous montrons que le bon débit de transmission est sélectionné moyennant un overhead très réduit de moins de 1%. En plus, la conception de notre protocole supporte la diffusion scalable de lavvidéo. Cette caractéristique vise à résoudre la problématique de la fluctuation de la bande passante, et à prendre en considération l'hétérogénéité des récepteurs dans un réseau sans fil.The multicast transport is an efficient solution to deliver the same content to many receivers at the same time. This mode is mainly used to deliver real-time video streams. However, the conventional multicast transmissions of IEEE 802.11 do not use any feedback policy. Therefore missing packets are definitely lost. This limits the reliability of the multicast transport and impacts the quality of the video applications. To resolve this issue, the IEEE 802.11v/aa amendments have been defined recently. The former proposes the Direct Multicast Service (DMS). On the other hand, 802.11aa introduces Groupcast with Retries (GCR) service. GCR defines two retry policies: Block Ack (BACK) and Unsolicited Retry (UR).In this thesis we evaluate and compare the performance of 802.11v/aa. Our simulation results show that all the defined policies incur an important overhead. Besides, DMS has a very limited scalability, and GCR-BACK is not appropriate for large multicast groups. We show that both DMS and GCR-BACK incur important transmission latencies when the number of the multicast receivers increases. Furthermore, we investigate the loss factors in wireless networks. We show that the device unavailability may be the principal cause of the important packet losses and their bursty nature. Particularly, our results show that the CPU overload may incur a loss rate of 100%, and that the delivery ratio may be limited to 35% when the device is in the power save mode.To avoid the collisions and to enhance the reliability of the multicast transmissions, we define the Busy Symbol (BS) mechanism. Our results show that BS prevents all the collisions and ensures a very high delivery ratio for the multicast packets. To further enhance the reliability of this traffic, we define the Block Negative Acknowledgement (BNAK) retry policy. Using our protocol, the AP transmits a block of multicast packets followed by a Block NAK Request (BNR). Upon reception of a BNR, a multicast member generates a Block NAK Response (BNAK) only if it missed some packets. A BNAK is transmitted after channel contention in order to avoid any eventual collision with other feedbacks, and is acknowledged. Under the assumption that 1) the receiver is located within the coverage area of the used data rate, 2) the collisions are avoided and 3) the terminal has the required configuration, few feedbacks are generated and the bandwidth is saved. Our results show that BNAK has a very high scalability and incurs very low delays. Furthermore, we define a rate adaptation scheme for BNAK. We show that the appropriate rate is selected on the expense of a very limited overhead of less than 1%. Besides, the conception of our protocol is defined to support the scalable video streaming. This capability intends to resolve the bandwidth fluctuation issue and to consider the device heterogeneity of the group members.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Support des applications multimédia dans les réseaux de prochaine génération

RÉSUMÉ Les applications multimédia sont devenues tellement populaires que certaines d’entre elles sont utilisées quotidiennement par les usagers. Cette popularité peut être attribuée à plusieurs facteurs, tels que la diversification du contenu et des services offerts, l’accès en tout temps grâce à la mobilité et à la nomadicité, ainsi qu’aux avancées au niveau des architectures et des protocoles utilisés, afin de supporter les requis plus exigeants de ces applications. Par exemple, ce qui était jadis un simple appel téléphonique, se transforme désormais en une vidéoconférence, permettant à un nombre dynamique d’usagers d’y participer. Un autre exemple d’application multimédia, qui connait également un essor fulgurant, est IP TeleVision (IPTV), soit la technologie permettant la transmission de la télévision, en direct et sur demande, sur des réseaux IP. On retrouve également sa version mobile, soit Mobile IP TeleVision (MobileTV). Du côté des opérateurs, le focus est mis sur le déploiement des réseaux de prochaine génération. Les opérateurs sans-fil se tournent vers les technologies cellulaires de quatrième génération, telles que 3GPP Long Term Evolution (LTE), alors que ceux qui offrent les services filaires regardent plutôt vers les réseaux basés sur la fibre optique, tels que Fiber to the Home (FTTH). Ces réseaux promettent d’augmenter le débit offert, ainsi que de réduire la latence, soit deux critères importants pour le déploiement des applications multimédia à grande échelle. Malgré ces avancées technologiques, il existe encore plusieurs obstacles au bon fonctionnement des applications multimédia. Dans cette optique, cette thèse se penche sur trois problématiques importantes dans les réseaux de prochaine génération, chacune faisant l’objet d’un article scientifique. Les deux premiers volets s’attardent sur la convergence des réseaux fixes et mobiles, ou Fixed-Mobile Convergence (FMC). Cette convergence vient brouiller la distinction entre les réseaux mobiles et les réseaux fixes. Entre autre, elle permet à un usager d’avoir accès à ses services, autant sur le réseau cellulaire (LTE, par exemple) que sur un réseau local (Wireless Fidelity (WiFi), par exemple). Pour s’y faire, l’usager est généralement muni d’un terminal pouvant se connecter sur les deux réseaux. La première problématique soulevée dans cette thèse est au niveau de la prise de décision de la relève. En effet, les deux protocoles de mobilité les plus populaires, soit Mobile IP (MIP) et Proxy Mobile IP (PMIP), adoptent deux approches diamétralement opposées. Avec le premier protocole, ce sont l’usager et son terminal qui prennent entièrement en charge la relève. Même si cette approche permet la FMC, les opérateurs préfèrent plutôt garder le contrôle sur la prise de décision, afin de pouvoir optimiser leur réseau. En effet, avec MIP, beaucoup de messages de signalisation sont envoyés, ce qui gaspille des ressources réseaux, surtout au niveau de l’accès radio, la partie la plus précieuse du réseau. De plus, en ne sollicitant pas le réseau, le terminal ne prend pas nécessairement les meilleures décisions. Il peut donc basculer vers un réseau qui est plus chargé et qui ne garantit pas nécessairement ses exigences au niveau de la qualité de service. De ce fait, le protocole PMIP a été proposé. Son approche est exactement à l’opposé de celle de MIP, soit la mobilité qui est entièrement gérée par le réseau. De ce fait, la mobilité est masquée au niveau du terminal, qui pense toujours se trouver dans son réseau mère. Grâce à l’ajout de nouveaux nœuds dans le réseau, qui gèrent la mobilité à la place du terminal, on élimine la signalisation sur l’accès radio. De plus, les informations supplémentaires que le réseau détient lui permettront de prendre une meilleure décision. Par contre, le problème avec ce protocole est que, sans l’intervention du terminal, il lui est impossible de détecter toutes les situations de relèves. Dans plusieurs cas, le réseau fixe de l’opérateur est masqué par un réseau interne, par exemple un réseau WiFi, et la détection de ce réseau n’est possible que grâce à l’intervention du terminal. Ainsi, PMIP n’est pas un protocole qui se prête bien au déploiement de FMC. Le premier article, qui s’intitule « Client-Based Network-Assisted Mobile IPv6 », s’attaque donc à ce problème, en proposant un nouveau protocole, basé sur Mobile IP v6 (MIPv6), et qui introduit l’implication du réseau. Le résultat obtenu est un protocole hybride qui combine les avantages de MIPv6 et de Proxy Mobile IP v6 (PMIPv6). Pour s’y faire, deux étapes ont été nécessaires. La première consiste en une refonte du protocole MIPv6 qui, dans son état actuel, était difficile à modifier, à cause de ses spécifications qui sont lourdes. Le résultat de cette étape est un protocole beaucoup plus léger et offrant uniquement les fonctionnalités de base. Les autres fonctionnalités, telles que les mécanismes de sécurité, ont été séparées dans des modules. En deuxième lieu, un nouveau module a été proposé, qui introduit un nouveau nœud dans le réseau, capable de gérer la mobilité du terminal. Ainsi, la collaboration entre le terminal et ce nœud permet de réduire les messages de signalisation et d’optimiser les décisions au niveau des relèves, tout en offrant le support pour FMC. La deuxième problématique, sur laquelle la thèse porte, se trouve au niveau de la transparence de la relève entre les deux réseaux. On parle d’une relève qui est transparente si cette dernière n’engendre aucune interruption des services de l’usager. Par exemple, un appel en cours, qui est démarré sur le réseau cellulaire, ne doit pas être interrompu lorsque la connexion bascule sur le réseau local, et vice-versa. Les applications visées, par notre travail, sont les applications multimédia en temps réél, notamment IPTV et MobileTV (en mode télévision en direct). Ces applications emploient des protocoles de multidiffusion permettant l’envoi optimisé de données à partir d’une ou de plusieurs sources vers plusieurs destinataires, avec un nombre minimal de paquets. Le problème avec ces applications est que, lorsqu’une relève verticale survient (dans le cadre de FMC par exemple), la connexion est rompue et doit être réétablie. Ceci est dû au fait que le terminal change son adresse IP, ce qui le force à rejoindre ses services à partir de la nouvelle adresse. Cette déconnexion résulte en une perte de paquets, se traduisant par une interruption de l’application de l’usager. Le second article, qui s’intitule « Seamless handover for multicast Mobile IPv6 traffic », propose une solution à ce problème. Cette solution consiste en l’ajout d’un nouveau nœud, dans le réseau, dont le rôle est de mettre en tampon les paquets perdus, lors de la relève du terminal. Ainsi, lorsque ce dernier recouvre sa connectivité, il est en mesure de récupérer ces paquets auprès de ce nœud. L’application de l’usager se déroule alors sans interruption. La troisième problématique abordée dans cette thèse porte sur la planification des réseaux d’accès, afin de supporter les requis des applications multimédia au niveau du débit. Pour que la FMC soit réussie, il faut que le réseau local puisse supporter les débits nécessaires de l’application. Le réseau WiFi interne n’étant généralement pas un problème, la limitation se trouve plutôt au niveau de l’accès filaire. Afin d’augmenter les débits offerts, les opérateurs ont introduit la fibre optique dans leurs réseaux, complémentant ainsi les méthodes traditionnelles, tels les paires de cuivre torsadées et le câble coaxial. Ainsi, de nouvelles technologies optiques hybrides ont été proposées. Dans un contexte o`u une infrastructure est déjà existante, le choix d’une technologie hybride est très attrayant, car l’opérateur peut rentabiliser son investissement précédent, minimisant ainsi le coût de la mise à jour. Par contre, dans un environnement vierge, il n’existe pas d’infrastructure à réutiliser. Le consensus, dans un tel scénario, est que la meilleure technologie à déployer est celle qui n’emploie que des liens en fibre optique, car elle offre les meilleurs débits ainsi que la plus grande flexibilité au niveau de l’évolutivité. La différence, au niveau du coût, devient moins grande et n’est plus nécessairement le critère principal au niveau du choix de la technologie à déployer. Une des difficultés, qui compliquent la planification, est que ces réseaux sont souvent déployés par les opérateurs, en phases. La planification doit être alors dynamique et prendre en considération la nature évolutive de la demande des clients. Le troisième article, qui s’intitule « Dynamic Greenfield Fiber to the Home Planning », propose donc une modélisation dynamique du problème de planification des réseaux d’accès en fibre optique. Le résultat est un modèle mathématique linéaire, en nombres entiers, qui prend en entrée des paramètres, tels que les demandes des clients, et qui produit la planification minimisant le coût total du réseau et ce, sur plusieurs phases. Les résultats numériques obtenus en simulant notre modèle montrent sa supériorité par rapport aux méthodes séquentielles existantes.--------- ABSTRACT Multimedia applications have been gaining momentum and are finding their way into everyday life. Their popularity can be attributed to several factors, such as the diversification of content and services, ubiquitous access thanks to the mobility and nomadicity, as well as advances in architectures and protocols used to support their most demanding requirements. For example, what was once a simple phone call has morphed nowadays into a videoconference, allowing a dynamic number of users to participate. Another example of a multimedia application that gained popularity is IP TeleVision (IPTV), which is the technology that allows the transmission of live and on demand television, on IP networks. There also exists a mobile version, called Mobile IP TeleVision (MobileTV). From the operators’ point of view, the focus is put on the deployment of next generation networks. Wireless operators are therefore deploying fourth generation cellular technologies, such as 3GPP Long Term Evolution (LTE), while those offering wired connectivity are looking into fiber optical based networks, such as Fiber to the Home (FTTH). These new networks increase the rate offered, as well as reduce latency, which are two important criteria for the deployment of large-scale multimedia applications. However, despite these advances, there still exist several obstacles hindering the proper operation of multimedia applications. This thesis therefore focuses on three important issues in next generation networks, each of these subjects leading to a scientific article. The first two works deal with the issues of the Fixed-Mobile Convergence (FMC). This convergence is blurring the distinction between mobile and fixed networks. Among other things, it allows a user to have access to its services, both on the cellular network (LTE, for example) as well as on a local network (Wireless Fidelity (WiFi), for example). This is usually accomplished by equipping the user with a device with that can connect to both networks. The first issue raised in this thesis is about the decision of when to execute a handover. The two most popular mobility protocols, Mobile IP (MIP) and Proxy Mobile IP (PMIP), approach this problem with diametrically opposed views. With the first protocol, the decision is made by the user and his device. Although this approach allows for FMC, operators would much rather have complete control over the decision-making, in order to optimize their network. Indeed, with MIP, many signaling messages are sent, wasting valuable network resources, especially at the radio access, which is the most precious part of the network. Furthermore, by not involving the network, the decision taken by the device will not be necessarily optimal. It might request to switch to a more overloaded network, that cannot meet its demands of Quality of Service (QoS). For these reasons, the PMIP protocol was proposed. Its approach is the opposite of that of MIP, the mobility being managed entirely by the network. By doing so, the device is actually shielded from any aspect of the mobility, and is fooled into thinking that its always in its home network. This is possible by introducing new nodes in the networks that act on its behalf, which eliminates all signaling on the radio link. In addition, since the network is usually better suited to make the right decision, because of the additional information it holds, the mobility is optimized. However, the big issue that arises is that, without the intervention of the terminal, it is impossible to detect all the handover possibilities. In many cases, the operator’s fixed network is hidden by an internal network, usually a WiFi network, and the detection of the network is only possible with the help of the terminal. Thus, PMIP is not a protocol that is well suited to deploy FMC. The first article, entitled “Client-Based Network-Assisted Mobile IPv6”, therefore addresses this problem by proposing a new protocol based on Mobile IP v6 (MIPv6), in which we introduce the involvement of the network. The result is a hybrid protocol that draws upon the strength of MIPv6 and Proxy Mobile IP v6 (PMIPv6). To accomplish this, two steps were required. The first consisted of a complete overhaul of the MIPv6 protocol, as in its current state, it was near impossible to make any modifications, because of the complexity and heaviness of its specifications. The result is a much more lightweight protocol which provides only basic functionality. Other features, such as security mechanisms, were separated into modules. In the second step, we proposed a new module, which introduces a new node in the network that can handle the terminal mobility. Thus, the collaboration of the terminal and the new node reduces the signaling messages and optimizes the decisions for handing over, while still offering support for FMC. The second issue that this thesis tackles is the seamlessness of a handover between two networks. A handover is deemed seamless if it does not cause any disruption to the user’s services. For example, a call that is in progress on the cellular network should not be interrupted when the connection switches to a local network, and the same goes for the other way around. The applications targeted by our work are multimedia applications operating in real-time , such as IPTV and MobileTV (in live television mode). These applications employ multicast protocols that are optimized for the transmission of data from one or more sources to multiple receivers, while using the minimum number of packets required. The problem, however, with these applications is that when a vertical handover occurs (in the case of FMC, for example), the connection is lost and must be re-established. This is because the terminal changes its IP address, which forces it to rejoin the services from the new address. This disconnection results in a packet loss, which entails an interruption of the user application. The second article, entitled “Seamless handover for multicast Mobile IPv6 traffic”, proposes a solution to this problem. This is accomplished by introducing a new node in the network, whose role is to buffer the lost packets while the handover is occurring. Thus, when the device reconnects, it is able to recover these packets. The user application is therefore able to proceed without interruption. The third issue addressed in this thesis focuses on the planning of access networks, to support the high bandwidth required by multimedia applications. For the FMC to be successful, it is necessary that the local network supports the bandwidth requirements. The internal WiFi network is generally not an issue, the limitation rather lies in the wired network. To increase the offered rates, operators have started introducing fiber optic links in their networks, complementing the traditional links, such as twisted pair copper and coaxial cable. Thus, new hybrid optical technologies have been proposed. In a context where an infrastructure already exists, the choice of a hybrid technology is very attractive, because the operator can leverage its previous investment and minimize the cost of the upgrade. However, in a new environment, there is no infrastructure to reuse. Therefore, the consensus in such a scenario is that the best technology to deploy is the one that only uses fiber optic links, as it offers the best rates and the greatest scalability. The cost difference is smaller and therefore no longer the main criterion for selecting the technology to deploy. One of the difficulties of network planning is that these networks are often deployed by operators in phases. Therefore, the planning must be dynamic and take into account the changing nature of customer demands. The third article, entitled “Dynamic Greenfield Fiber to the Home Planning”, proposes a dynamic model for the network planning problem of fiber optic networks. The result is a linear integer mathematical model, which takes input parameters, such as customer demands, and produces a planning that minimizes the total cost of the network, over all of the phases. The numerical results obtained when simulating our solution show its superiority compared to existing sequential methods

Journal of Telecommunications and Information Technology, 2011, nr 2

kwartalni

Airport master plan update: Manchester- Boston regional airport, Manchester, New Hampshire

Draft appendices to the update for the Manchester-Boston Regional Airport master plan, assessing zoning area, flight and terminal data

Air Traffic Management Abbreviation Compendium

As in all fields of work, an unmanageable number of abbreviations are used today in aviation for terms, definitions, commands, standards and technical descriptions. This applies in general to the areas of aeronautical communication, navigation and surveillance, cockpit and air traffic control working positions, passenger and cargo transport, and all other areas of flight planning, organization and guidance. In addition, many abbreviations are used more than once or have different meanings in different languages. In order to obtain an overview of the most common abbreviations used in air traffic management, organizations like EUROCONTROL, FAA, DWD and DLR have published lists of abbreviations in the past, which have also been enclosed in this document. In addition, abbreviations from some larger international projects related to aviation have been included to provide users with a directory as complete as possible. This means that the second edition of the Air Traffic Management Abbreviation Compendium includes now around 16,500 abbreviations and acronyms from the field of aviation