L'augmentation de l'utilisation de l'Internet et des services de données motive l'évolution des réseaux cellulaires de troisième. Dans ce contexte, HSDPA (High Speed Downlink Packet Access) a été développé dans les releases 5 et 6 au sein de 3GPP pour poursuivre l'évolution du mode "paquet" de l'UMTS. Ce système utilise de nouvelles technologies telles que le Hybrid-ARQ (Automatic Repeat Request), la modulation adaptative et l'ordonnancement rapide (fast Scheduling) pour permettre de véhiculer des débits plus élevés sur l'interface radio et d'augmenter la capacité. Cette thèse se focalise sur l'analyse et la modélisation des interactions entre la couche MAC-hs de HSDPA et les autres couches (physique, transport). L'objectif est de trouver la configuration optimale de cette entité MAC-hs afin de réduire les interactions "négatives" entre-couches et optimiser les performances de HSDPA. Par conséquent, cette thèse fournit des études et des modélisations analytiques couvrant les aspects suivants: -Analyse et modélisation de l'impact du canal radio (shadowing, fast fading) sur les performances du système HSDPA dans le cas où plusieurs "schedulers" sont utilisés -Analyse et modélisation de l'effect des services "Circuit" de l'UMTS R99 sur les performances de HSDPA. -Modélisation de l'interaction entre le protocole TCP et l'entité MAC-hs. Une nouvelle stratégie d'ordonnancement est proposée afin d'améliorer les performances du système -Charactérisation de l'interaction entre MAc-hs et les services streaming. Une nouveau "scheduler" est proposé afin de garantir les contraintes sévères de QoS des services streaming sans trop perdre de capacité cellulaire.

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<p>The healing process of human bone can be aided by the presence of differentmaterials. A material that is transformed into bone when in contact with bone iscalled a boneconductive material. By transforming into bone the material reduces thetime that it takes to heal a fracture. This report is a study of existing boneconductivematerials on the market to see if there is a material available that would be suitable totest on larger fractures. The wanted application is to be able to heal fractures up to50 mm which is a fracture too big for the body to heal on its own.The healing process of human bone can be aided by the presence of differentmaterials. A material that is transformed into bone when in contact with bone iscalled a boneconductive material. By transforming into bone the material reduces thetime that it takes to heal a fracture. This report is a study of existing boneconductivematerials on the market to see if there is a material available that would be suitable totest on larger fractures. The wanted application is to be able to heal fractures up to50 mm which is a fracture too big for the body to heal on its own.</p>

Achieving high performance in high capacity data transfers over the Internet has long been a daunting challenge. The current standard of Transmission Control Protocol (TCP), TCP Reno, does not scale efficiently to higher bandwidths. Various congestion controllers have been proposed to alleviate this problem. Most of these controllers primarily use marking/loss or/and delay as distinct feedback signals from the network, and employ separate data transfer control strategies that react to either marking/loss or delay. While these controllers have achieved better performance compared to existing TCP standard, they suffer from various shortcomings. Thus, in our previous work, we designed a congestion control scheme that jointly exploits both delay and marking; D+M (Delay Marking) TCP. We demonstrated that D+M TCP can adapt to highly dynamic network conditions and infrastructure using ns-2 simulations. Yet, an analytical explanation of D+M TCP was needed to explain why it works as observed. Furthermore, D+M TCP needed extensive simulations in order to assess its performance, especially in relation to other high-speed protocols. Therefore, we propose a model for D+M TCP based on distributed resource optimization theory. Based on this model, we argue that D+M TCP solves the network resource allocation problem in an optimal manner. Moreover, we analyze the fairness properties of D+M TCP, and its coexistence with different queue management algorithms. Resource optimization interpretation of D+M TCP allows us to derive equilibrium values of steady state of the controller, and we use ns-2 simulations to verify that the protocol indeed attains the analytical equilibria. Furthermore, dynamics of D+M TCP is also explained in a mathematical framework, and we show that D+M TCP achieves analytical predictions. Modeling the dynamics gives insights to the stability and convergence properties of D+M TCP, as we outline in the thesis. Moreover, we demonstrate that D+M TCP is able to achieve excellent performance in a variety of network conditions and infrastructure. D+M TCP achieved performance superior to most of the existing high-speed TCP versions in terms of link utilization, RTT fairness, goodput, and oscillatory behavior, as confirmed by comparative ns-2 simulations.

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The healing process of human bone can be aided by the presence of differentmaterials. A material that is transformed into bone when in contact with bone iscalled a boneconductive material. By transforming into bone the material reduces thetime that it takes to heal a fracture. This report is a study of existing boneconductivematerials on the market to see if there is a material available that would be suitable totest on larger fractures. The wanted application is to be able to heal fractures up to50 mm which is a fracture too big for the body to heal on its own.The healing process of human bone can be aided by the presence of differentmaterials. A material that is transformed into bone when in contact with bone iscalled a boneconductive material. By transforming into bone the material reduces thetime that it takes to heal a fracture. This report is a study of existing boneconductivematerials on the market to see if there is a material available that would be suitable totest on larger fractures. The wanted application is to be able to heal fractures up to50 mm which is a fracture too big for the body to heal on its own.

In this dissertation we examine some of the challenges faced by the congestion control algorithms of TCP in emerging networks. We focus on three main issues. First, we propose TCP with delayed congestion response (TCP-DCR), for improving performance in the presence of non-congestion events. TCP-DCR delays the conges- tion response for a short interval of time, allowing local recovery mechanisms to handle the event, if possible. If at the end of the delay, the event persists, it is treated as congestion loss. We evaluate TCP-DCR through analysis and simulations. Results show significant performance improvements in the presence of non-congestion events with marginal impact in their absence. TCP-DCR maintains fairness with standard TCP variants that respond immediately. Second, we propose Layered TCP (LTCP), which modifies a TCP flow to behave as a collection of virtual flows (or layers), to improve eficiency in high-speed networks. The number of layers is determined by dynamic network conditions. Convergence properties and RTT-unfairness are maintained similar to that of TCP. We provide the intuition and the design for the LTCP protocol and evaluation results based on both simulations and Linux implementation. Results show that LTCP is about an order of magnitude faster than TCP in utilizing high bandwidth links while maintaining promising convergence properties. Third, we study the feasibility of employing congestion avoidance algorithms in TCP. We show that end-host based congestion prediction is more accurate than previously characterized. However, uncertainties in congestion prediction may be un- avoidable. To address these uncertainties, we propose an end-host based mechanism called Probabilistic Early Response TCP (PERT). PERT emulates the probabilistic response function of the router-based scheme RED/ECN in the congestion response function of the end-host. We show through extensive simulations that, similar to router-based RED/ECN, PERT provides fair bandwidth sharing with low queuing delays and negligible packet losses, without requiring the router support. It exhibits better characteristics than TCP-Vegas, the illustrative end-host scheme. PERT can also be used for emulating other router schemes. We illustrate this through prelim- inary results for emulating the router-based mechanism REM/ECN. Finally, we show the interactions and benefits of combining the different proposed mechanisms.

This thesis analyzes the performance of Quantized Congestion Notification (QCN) during data access from clustered servers in data centers. The reasons why QCN does not perform adequately in these situations are examined and several modifications are proposed to the protocol to improve its performance in these scenarios. The causes of QCN performance degradation are traced to flow rate variability, and it is shown that adaptive sampling at the switch and adaptive self-increase of flow rates at the QCN rate limiter significantly enhance QCN performance in a TCP Incast setup. The performance of QCN is compared against TCP modifications in a heterogeneous environment, and it is shown that modifications to QCN yield better performance. Finally, the performance of QCN with the proposed modifications is compared with that of unmodified QCN in other workloads to show that the modifications do not negatively affect QCN performance in general.

In the twenty century multimedia entertainment is more and more proportion in the human life and internet is more covenient to communicate and easier to change information. Video and audio compression technology are promote rapidly to drive people enjoying multimedia contents by using internet. However, the main three software factory provide high price of multimedia streaming technology and they have each patents on their multimedia streaming technology. From MP3 encoding technology view, it is used efficient to compress music data and let it be in trade of data size and high quality. MP3 file format is much appropriate to apply using many kinds based on streaming music applications. The technique in my paper, first I analysis MP3 encoding and deconding algorithm. Then I apply it in transferring streaming music by using reliable TCP/IP communication protocol to make multi-user and multi-channel music-on-demand system. By using Java server side technology, I make a web-based manager and user interface system and finally make the implementation of linux-based MP3 music-on-demand system.

TCP is the most popular transport layer protocol. When there is congestion in the network, either sender¡¦s TCP or router¡¦s buffer management has its way to resist the penalties of congestion. But each of them achieves this goal in an independent way. In TCP, Tahoe, Reno, New Reno, SACK, Vegas, FACK, and some modifications to TCP to improve performance were proposed. Although they have better performance than previous TCP, the cooperation between different types of TCP is not well. And TCP-unfriendly connections will be adverse to TCP connections. In buffer management, the fairness between different connections can be maintained. But some phenomena will be adverse to TCP connection because of buffer management is TCP-unawareness. In this paper, we show a problem that buffer management scheme may be unfriendly to new connection which is going to join the network with congestion. This problem will incur (1) TCP-unfriendly behavior, (2) alleviating congestion inefficiently, (3) unfairness between two connections. We propose a scheme to alleviate this problem and this scheme is easy to implement with existing buffer management scheme.