Le domaine de la mesure des caractéristiques du trafic transitant sur un réseau a été largement traité par une vaste communauté de chercheurs, en premier lieu pour répondre aux attentes des opérateurs fournisseurs d'accès à Internet. En effet, leur première préoccupation est de savoir quel type de trafic ils doivent transporter. Une des principales caractéristiques de l'Internet est qu'il évolue très vite, de sorte que le besoin de mesures du trafic grand public ne se tarit jamais. Dans ce travail, nous abordons la question de la mesure du trafic Internet grand public par deux perspectives différentes: les mesures passives et les mesures actives. Dans la première partie de cette thèse, nous capturons et analysons passivement les statistiques des connections d'utilisateurs d'Internet durant plus d'une semaine. Nous utilisons ces données pour réviser et approfondir notre connaissance du trafic Internet résidentiel. Ensuite, nous utilisons des méthodes de regroupement pour créer des ensembles d'utilisateurs en fonctions des applications qu'ils utilisent. Nous apprenons donc qu'une vaste majorité des clients se connectent à Internet principalement pour surfer sur le Web et regarder des vidéos en streaming. Ces données nous servent aussi à évaluer de nouvelles possibilités de contrôler le trafic d'une plateforme ADSL. Comme la principale partie du trafic provient du vidéo streaming, nous prenons plusieurs instantanés de ce trafic avec des captures paquet durant une période de plusieurs années, ceci pour comprendre précisément l'évolution de ce trafic. De plus, nous analysons et relions la performance du vidéo streaming, définie par des indicateurs de qualité de service, au comportement des utilisateurs de ce service. Dans la deuxième partie de cette thèse, nous tirons parti de cette connaissance pour concevoir une sonde active capable de mesurer la qualité d'expérience des sites de vidéo streaming. Nous avons modélisé la lecture des vidéos \emph{streaming} pour pouvoir déterminer leur qualité telle qu'elle est perçue par les utilisateurs. Grâce à cet outil, nous pouvons comprendre l'impact de la sélection du serveur vidéo et du serveur DNS sur la perception de la qualité vidéo par l'utilisateur. De plus, la possibilité de réaliser des mesures depuis divers opérateurs, nous permet de détailler les politiques de distribution vidéo utilisées par les sites de streaming. / Network tomography is the study of a network's traffic characteristics using measures. This subject has already been addressed by a whole community of researchers, especially to answer the need for knowledge of residential Internet traffic that ISPs have to carry. One of the main aspects of the Internet is that it evolves very quickly, so that there is a never ending need for Internet measurements. In this work, we address the issue of residential Internet measure from two different perspectives: passive measurements and active measurements. In the first part of this thesis, we passively collect and analyse statistics of residential users' connections spanning over a whole week. We use this data to update and deepen our knowledge of Internet residential traffic. Then, we use clustering methods to form groups of users according to the application they use. This shows how the vast majority of customers are now using the Internet mainly for Web browsing and watching video Streaming. This data is also used to evaluate new opportunities for managing the traffic of a local ADSL platform. As the main part of the traffic is video streaming, we use multiple snapshots of packet captures of this traffic over a period of many years to accurately understand its evolution. Moreover we analyse and correlate its performance, defined out of quality of service indicators, to the behavior of the users of this service. In the second part of this thesis, we take advantage of this knowledge to design a new tool for actively probing the quality of experience of video streaming sites. We have modeled the playback of streaming videos so that we are able to figure out its quality as perceived by the users. With this tool, we can understand the impact of the video server selection and the DNS servers on the user's perception of the video quality. Moreover the ability to perform the experiments on different ISPs allows us to further dig into the delivery policies of video streaming sites.

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Identifying the influence of eastern boundary current (EBC) dynamical processes on sound speed structure can provide better ocean models for acoustic predictions in littoral regions. This study will explore the effects of currents, wind and eddies on the sound speed structure of two different EBC models, the North Canary Current System (NCCS) and the Leeuwin Current System (LCS). These systems represent classical features of EBCs as well as regional anomalies. This study seeks to introduce sound speed analysis to the sigma coordinate primitive equation models and determine which regions of EBCs experience the largest changes in sound speed and most intense gradients. Results of model runs show that the dynamics of EBCs lead to large changes in sound speed and distort the vertical sound speed profile. The greatest change in sound speed in either region is caused by upwelling in the NCCS. Surface and associated subsurface eddies in the LCS are the largest scale feature in the study. The undercurrent of the NCCS and Meddies present the most intense (horizontal and vertical) gradients of sound speed change. / US Navy (USN) author.

Hui Shui Cheung. / Thesis submitted in: August 2005. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 37-38). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / 摘要 --- p.iii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Related Work --- p.4 / Chapter Chapter 3 --- Single-Source Bandwidth Availability --- p.6 / Chapter 3.1 --- Measurement Methodology --- p.6 / Chapter 3.2 --- Measurement Results --- p.7 / Chapter Chapter 4 --- Multi-Souce Bandwidth Availability --- p.9 / Chapter 4.1 --- Correlation Among Senders --- p.9 / Chapter 4.2 --- Aggregate Bandwidth --- p.10 / Chapter 4.3 --- Sensitivity Analysis --- p.11 / Chapter Chapter 5 --- The Measurement System --- p.15 / Chapter 5.1 --- Overview of PlanetLab --- p.15 / Chapter 5.2 --- Measurement Tool --- p.16 / Chapter 5.3 --- Process Control --- p.17 / Chapter Chapter 6 --- Hybrid-Download Streaming --- p.21 / Chapter 6.1 --- Introduction --- p.21 / Chapter 6.2 --- Streaming Algorithm --- p.22 / Chapter 6.3 --- Performance Evaluation --- p.23 / Chapter Chapter 7 --- Playback-Adaptive Streaming --- p.26 / Chapter 7.1 --- Introduction --- p.26 / Chapter 7.2 --- Streaming Algorithm --- p.27 / Chapter 7.3 --- Adaptive Rebuffering Algorithm --- p.30 / Chapter 7.4 --- Performance Evaluation --- p.31 / Chapter Chapter 8 --- Conclusion --- p.36 / Bibliography --- p.37

Video streaming is an increasingly popular Internet application. However, despite its popularity, real-time video streaming still remains a challenge in many scenarios. Limited home broadband bandwidth and mobile phone 3G bandwidth means many users stream videos at low quality and compromise on their user experience. To overcome this problem, we propose CStream, a system that aggregates bandwidth from multiple co-operating users in a neighborhood environment for better video streaming. CStream exploits the fact that wireless devices have multiple network interfaces and connects co-operating users with a wireless ad-hoc network to aggregate their unused downlink Internet bandwidth to improve video quality. CStream dynamically generates a streaming plan to stream a single video using multiple connections and continuously adapts to changes in the neighborhood and variations in the available bandwidth. We have built CStream and evaluated it on a controlled test-bed of computers with various performance measures. The results show linear increase in throughput and improved video streaming quality as the number of cooperating users in a neighborhood increase.

Lam Ling Shun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 75-76). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / 摘要 --- p.iii / Chapter Part I - --- A Transparent Rate Adaptation Algorithm for Streaming Video Over The Internet --- p.1 / Chapter Chapter 1 --- Introduction --- p.2 / Chapter Chapter 2 --- Related Work --- p.5 / Chapter Chapter 3 --- System Model --- p.8 / Chapter Chapter 4 --- Client Buffer Occupancy and Network Bandwidth Estimation --- p.12 / Chapter Chapter 5 --- Rate Adaptation --- p.16 / Chapter 5.1 --- Segment-based Rate Control --- p.16 / Chapter 5.2 --- Preemptive Rate Control --- p.18 / Chapter Chapter 6 --- Performance Evaluation --- p.20 / Chapter 6.1 --- Sensitivity to Prefetch Duration --- p.22 / Chapter 6.2 --- Effectiveness of Preemptive Rate Control --- p.24 / Chapter 6.3 --- Comparison with the CR algorithm --- p.25 / Chapter Chapter 7 --- Conclusions --- p.28 / Bibliography --- p.29 / Chapter Part II - --- Buddy-TCP - A Sender-driven Algorithm for Bandwidth Reallocation Among TCP Flows --- p.31 / Chapter Chapter 1 --- Introduction --- p.32 / Chapter Chapter 2 --- Background --- p.36 / Chapter 2.1 --- Flow Control --- p.36 / Chapter 2.2 --- Congestion Control --- p.37 / Chapter Chapter 3 --- Buddy-TCP --- p.39 / Chapter 3.1 --- Sender Protocol Stack --- p.39 / Chapter 3.2 --- Joint Congestion Window Update --- p.42 / Chapter Chapter 4 --- Performance Study --- p.47 / Chapter 4.1 --- Performance Metrics --- p.48 / Chapter 4.2 --- Bandwidth Allocation Accuracy --- p.50 / Chapter 4.3 --- Impact on Ordinary TCP Flows --- p.52 / Chapter 4.4 --- Effect of Heterogeneous RTTs --- p.55 / Chapter 4.5 --- Effect of Random Packet Loss --- p.58 / Chapter 4.6 --- Effect of TCP SACK --- p.62 / Chapter 4.7 --- Effect of Abrupt Link Congestion --- p.64 / Chapter 4.8 --- Convergence --- p.66 / Chapter Chapter 5 --- Implementation and Experimental Results --- p.68 / Chapter 5.1 --- Implementation --- p.68 / Chapter 5.2 --- Experimental Results --- p.69 / Chapter Chapter 6 --- Conclusions --- p.73 / Bibliography --- p.75

Ho Tsz Kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 47-49). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / 摘要 --- p.iii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Background --- p.4 / Chapter 2.1 --- The Server-less Architecture --- p.4 / Chapter 2.2 --- Related Works --- p.6 / Chapter Chapter 3 --- Row-Permutated Data Reorganization --- p.9 / Chapter 3.1 --- Placement Policy --- p.9 / Chapter 3.2 --- Data Reorganization --- p.11 / Chapter 3.3 --- Multi-Row-Perm utated Data Reorganization --- p.12 / Chapter 3.4 --- Performance Evaluation --- p.15 / Chapter 3.4.1 --- Data Reorganization Overhead --- p.15 / Chapter 3.4.2 --- Streaming Load Balance --- p.19 / Chapter Chapter 4 --- Sequential Redundant Data Update --- p.21 / Chapter 4.1 --- Redundant Data Regeneration --- p.21 / Chapter 4.2 --- Redundant Data Encoding --- p.22 / Chapter 4.3 --- Reuse of Original Redundant Data --- p.25 / Chapter 4.4 --- Parity Group Reshuffling --- p.26 / Chapter 4.5 --- Reuse of Transmitted Data --- p.28 / Chapter 4.6 --- Redundant Data Update Overhead --- p.29 / Chapter Chapter 5 --- Transpositional Redundant Data Update --- p.32 / Chapter 5.1 --- SRDU Revisited --- p.32 / Chapter 5.2 --- Redundant Data Encoding --- p.34 / Chapter 5.3 --- Redundant Data Update --- p.35 / Chapter 5.4 --- Zero Overhead Points --- p.37 / Chapter 5.5 --- Redundant Data Update Overhead --- p.38 / Chapter 5.6 --- Comparing SRDU and TRDU --- p.40 / Chapter Chapter 6 --- Multiple Redundant Nodes --- p.41 / Chapter Chapter 7 --- Conclusion and Future Work --- p.45 / Bibliography --- p.47

Chan Chi Yuk. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 41-42). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / 摘要 --- p.iii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Background --- p.4 / Chapter 2.1 --- Server-less Video Streaming Architecture --- p.4 / Chapter 2.2 --- Network Congestion --- p.6 / Chapter Chapter 3 --- Network-Neutral Schedulers --- p.9 / Chapter 3.1 --- Randomized Scheduler --- p.9 / Chapter 3.2 --- Staggered Scheduler --- p.10 / Chapter 3.3 --- Staggered-on-Request Scheduler --- p.11 / Chapter Chapter 4 --- A Model for Transmission Scheduling --- p.13 / Chapter 4.1 --- Matrix Representation --- p.13 / Chapter 4.2 --- Parameter Estimation --- p.17 / Chapter Chapter 5 --- Network Aware Schedulers --- p.20 / Chapter 5.1 --- Gradient Descent Scheduler --- p.20 / Chapter 5.2 --- Least Schedulable First Scheduler --- p.23 / Chapter 5.3 --- Performance Analysis --- p.26 / Chapter Chapter 6 --- Performance Evaluation --- p.30 / Chapter 6.1 --- Sensitivity to Clock Jitter --- p.32 / Chapter 6.2 --- Sensitivity to System Size --- p.34 / Chapter 6.3 --- Sensitivity to System Utilization --- p.35 / Chapter 6.4 --- Sensitivity to Delay Variation --- p.36 / Chapter 6.5 --- Sensitivity to Router Buffer Size --- p.38 / Chapter Chapter 7 --- Conclusions --- p.39 / Bibliography --- p.41

Chow Lik Hang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 100-102). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Multimedia Streaming Background --- p.2 / Chapter 1.2 --- Streaming over the Internet --- p.2 / Chapter 1.3 --- Traditional Approaches --- p.4 / Chapter 1.4 --- Document Road-map --- p.6 / Chapter 2 --- Related Work --- p.8 / Chapter 3 --- Our Multi-path Streaming Approach --- p.11 / Chapter 3.1 --- Potential Benefits --- p.14 / Chapter 3.2 --- Performance Metrics --- p.15 / Chapter 3.3 --- Visual Quality of Data --- p.15 / Chapter 3.3.1 --- Experiment: Effect of Correlated Bursty Losses on Video Quality --- p.16 / Chapter 4 --- Performance Evaluation using Gilbert Model --- p.18 / Chapter 4.1 --- Mathematical analysis --- p.18 / Chapter 4.1.1 --- Model --- p.19 / Chapter 4.1.2 --- Performance Analysis of SP vs. Multi-path Streaming (without FEC) --- p.20 / Chapter 4.1.3 --- Performance Analysis of SP vs. Multi-path Streaming (with FEC) --- p.26 / Chapter 4.2 --- Analytical Model Based Evaluation --- p.32 / Chapter 5 --- Functional Gilbert Model and Optimization --- p.45 / Chapter 5.1 --- Functional Gilbert Model --- p.45 / Chapter 5.2 --- Optimal Traffic Splitting --- p.48 / Chapter 5.2.1 --- Optimization Based on Achieved Loss Rate --- p.49 / Chapter 5.2.2 --- Optimization Based on Lag-1 Autocorrelation --- p.54 / Chapter 5.3 --- Experiments --- p.58 / Chapter 5.3.1 --- Type A Experiment: Without an Erasure Code --- p.59 / Chapter 5.3.2 --- Type B Experiment: with an Erasure Code --- p.62 / Chapter 6 --- NS Simulations --- p.68 / Chapter 6.1 --- Simulation Setup --- p.68 / Chapter 6.2 --- Simulation Result --- p.70 / Chapter 7 --- Quantization of Traffic Splitting Vector --- p.80 / Chapter 8 --- Prototype Implementation and Experiments --- p.86 / Chapter 8.1 --- Multi-path Streaming Prototype --- p.86 / Chapter 8.2 --- Experiments --- p.87 / Chapter 9 --- Other Design Issues and Considerations --- p.93 / Chapter 9.1 --- Requirements and Overheads --- p.93 / Chapter 9.2 --- Share Point of Congestion (SPOC) --- p.96 / Chapter 10 --- Conclusion --- p.98 / Bibliography --- p.100

Dissertação (Mestrado em Engenharia Mecânica) - Centro Universitário da FEI, São Bernardo do Campo, 2014