Global ETD Search

1	Robust packet multicast service over a satellite link Kok, Tan Cheng January 1997 (has links) The aim of this thesis is to investigate and understand the issues involved in using multicast communications over a non-reliable satellite link and to suggest suitable methods to improve multicast services when used on packet networks. Point-to-multipoint communications have been used for distribution of data. These are mainly found on circuit switched networks where there is bandwidth allocation, ensuring a good transmission link. However, as packet switched networks become more evolved due to their interesting properties of being able to share the available bandwidth, multicast communication is increasingly employed. A satellite link in a packet network is often used to provide connection to remotely located hosts. To use point-to-multipoint communications, especially for real-time applications, across a satellite link, a scheme employing Forward Error Correction (FEC) is presented. The scheme uses an XOR (Exclusive-OR) coding technique to generate the redundancy. It adjusts the rate of coding according to the varying condition of the link. By using this transmission strategy, the proposed scheme is implemented at the transport and the data link layer to enhance multicast communication services. In recent years, there has been a tremendous growth in the number of local and wide area networks. To manage these networks, it is necessary to monitor and analyse the network traffic regularly. Many commercially available analysers are either too expensive or too complicated. Perhaps the greatest setback lies in their presentation of vital information to the users in the form of screen after screen of textual data. Thus, it may require someone of experience to be able to fully understand the situation on the network and this, only after a detailed study of the data. The thesis investigates and proposes a new method of processing and presenting the information that will enhance the flexibility and productivity in the process of network troubleshooting. 621.382
2	Multicommodity flow applied to the utility model: a heuristic approach to service level agreements in packet networks Yu, Louis Lei 16 December 2005 (has links) Consider the concept of the Utility Model [5]: the optimal allocation of resources of a server or network while meeting the absolute Quality of Service (QoS) requirements of users' multimedia sessions. Past algorithms and heuristics to solve the Utility Model mapped the problem onto a variant of the Combinatorial Knapsack Problem, with server utility (e.g. revenue) as the quantity to be optimized and with user QoS requirements expressed as constraints on the resource allocation. Both optimal (algorithmic) and fast but sub-optimal (heuristic) methods were derived to solve the resulting Multidimensional Multiconstraint Knapsack Problem (MMKP) and hence to perform admission control of proposed user sessions However, previous algorithms and heuristics were restricted to solving the Utility Model on an enterprise network (a network of less than 30 nodes), owing to the need in admission control to solve the problem in real time, typically a few seconds or less. The methods used for the path finding and admission processes had unfavorable computational complexities. As a result, only small (i.e. enterprise) networks could be treated in real time. Also, considerable time was wasted on frequently unnecessary traversals during upgrading. In this thesis we attempt to solve and implement the Utility Model using a modified version of a Multicommodity Flow algorithm, which has better computational complexity than Knapsack Algorithms or many heuristics and hence is capable of finding paths relatively quickly for larger networks. What's more, the Multicommodity flow algorithm used keeps essential information about the current networks and user sessions, thus further reducing the overall admission time. Quality of Service QoS MMKP algorithms packet networks
3	Measurement Based Optimal Source Shaping In Integrated Services Packet Networks Dube, Parijat 10 1900 (has links) (PDF) No description available. Packet Switching Leaky Bucket Algorithm Optimal Source Shaping Communication Engineering
4	Qos In Cognitive Packet Networks: Adaptive Routing, Flow And Congestion Control Su, Pu 01 January 2005 (has links) With the emergence of various applications that have different Quality of Service (QoS) requirements, the capability of a network to support QoS becomes more and more important and necessary. This dissertation explores QoS in Cognitive Packet Networks (CPN) by using adaptive routing, flow and congestion control. We present a detailed description and analysis of our proposed routing algorithms based on single and multiple QoS constraints. An online estimation of packet loss rate over a path is introduced. We implement and evaluate the adaptive routing scheme in an experimental CPN test-bed. Our experiments support our claims that the users can achieve their desired best-effort QoS through this routing scheme. We also propose a QoS-based flow and congestion control scheme that is built in the transport layer and specially designed to work with CPN to support users' QoS while remaining friendly to TCP. Theoretical models and experimental analysis are presented. Finally we experimentally demonstrate that the proposed flow and congestion control scheme can effectively control the input flows, react to the congestion and work with our proposed adaptive routing scheme to achieve users' QoS. Quality of Service Routing Flow and Congestion Control Cognitive Packet Networks Computer Sciences Engineering
5	Conception et étude des performances d'une solution auto-configurable pour les réseaux de transport du futur / Design and performances study of a self-configurable solution for future transport networks Le Quéré, Damien 16 June 2015 (has links) Dans cette thèse, nous étudions la solution LOCARN : ''Low Opex & Capex Architecture for Resilient Networks''. LOCARN est une architecture de réseaux paquet alternative conçue dans une optique de simplicité de sa structure et ses mécanismes tout en permettant par sa conception la résilience et l'auto-adaptation des services de transport clients. Compte tenu de la complexification croissante des réseaux de transport opérateurs ces dernières décennies, nous prenons ces réseaux comme cas d'usage privilégié. Dans ce cadre, LOCARN permet une simplification considérable des composants et de leur gestion en comparaison des solutions actuelles des opérateurs – ce qui implique respectivement des réductions de CAPEX et d'OPEX. Dans le travail qui suit, nous présentons LOCARN techniquement et mettons en évidence ses intérêts pour les opérateurs par rapport aux autres technologies de transport. Puis, la question prioritaire étant la capacité de mise à l'échelle de LOCARN pour des réseaux de grandes dimensions, nous étudions cette question en détails ce qui nous permet d'établir que l'architecture est tout à fait capable de passer à l'échelle dans des réseaux de transport réalistes. En outre, pour améliorer les performances nous avons également spécifié et évalué deux améliorations de conception permettant à l'architecture de transporter d'un très grand nombre de services, les résultats obtenus sont très encourageants. / In this thesis, we study the LOCARN solution “Low Opex & Capex Architecture for Resilient Networks". LOCARN is an alternative packet network architecture that has been conceived with a special attention to the simplicity of its structure and mechanisms while allowing by design the resiliency and the self-adaptation of clients transportation services. Considering the growing complexification of operators transport networks during the last decades, we consider these latter as the privileged use case. In such a context, LOCARN would allow a drastical simplification of devices and their operation compared to common operator solutions – this involves respectively reductions of CAPEX and OPEX. In this work, we first present LOCARN technically and we bring out its interests for operators beside other transport technologies. Then, since the primary issue of LOCARN is it scalability for large networks, we study this point in details which allow us to establish that the architecture is altogether capable to scale in realistics transport networks. Moreover, to increase the performances we specified two design improvements allowing the architecture to transport a huge amount of clients, the obtained results are very encouraging. Architecture réseau Réseaux paquet Auto-Configuration Opex Capex Network architecture Packet networks Self-Configuration Opex Capex 004.65
6	Changing from the silo model to the horizontal layers model in public policy regulations: the implications and potential for the telecommunications industry Spencer Logan, Lemuella C. 12 1900 (has links) The end of the Twentieth Century and the start of the Twenty First Century has been a tumultuous time for the Telecommunications Industry. Even as it moves forward to embrace the new technologies the Industry finds itself embroiled in issues of governance. The Industry finds itself in a dilemma since innovations increase at a rate faster than the laws can be changed and these render its existing laws and policies to be in some cases obsolete and inappropriate for the reality of the present. In the past, the United States of America has relied on vertically integrated top down laws and methods of regulating all the different parts in its Telecommunications Industry. These laws are contained in the different numbered Titles of this Countrys Legal Codes. Since the inception of these laws, emphasis was placed in creating and documenting policies structured by industry, sector and type of content. This form of regulation is usually referred to as the Silo Method. However, in recent years, especially in the regulation of the Telephony industry, the method of law and rule formulation moved from content regulation to one in which the technologies are getting regulated in what has been described as a Layers Method. This paper first considered whether the Silo Method of regulation is in actuality the same as using the Horizontal Layers method and showed that this is the case. Then it determined that Enhanced Services are the same as Basic Services and that Telecommunications Services are the same as Information services and showed that given that the pair sets as noted were the same, it went on to conclude that all these services were essentially the same. While studying to some detail the technologies of VoIP, the paper also showed that VoIP although an Internet technology is similar to traditional telephony, and is both a Telecommunications Service and Information Service based on the definition as given in the law as well as the technologies that are used and that as a result of this, the current regulatory environment for this service with regards to telephony is inconsistent. It concluded that Telecommunications policies though now adequate may need to be modified. Telecommunication/Internet Issues Telecommunications regulations Cable networks Cellular networks Common carriers Competitive carriers Computer inquiries Convergence Deregulation Digital networks FCC Federal Communications Commission Fiber optics Gatekeepers Gateways H.323 Horizontal Layers Model ICANN ILECs Information services Intelligent Network Architecture ISDN LAN LECs Loops LRN Call Flow MAN Network speed Networks NTIA OSI Model OSS Packet networks Packet switches Policies Protocols PSTN Networks PUCs Regulation SIP Spam SPY ACT Switched networks TC/IP Protocol Telecommunications Act of 1996 Telecommunications regulations Unbundled access UNCTAD UNICITRAL Vertical Silo Model VoIP VPN WAN Wireless Telecommunication Law and legislation Telecommunication Law and legislation

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