Dissertations / Theses on the topic 'QoS estimation'

Progressive download video services, such as YouTube and podcasts, are responsible for a major part of the transmitted data volume in the Internet and it is expected, that they will also strongly affect mobile networks. Streaming video quality mainly depends on the sustainable throughput achieved during transmission. To ensure acceptable video quality in mobile networks (with limited capacity resources) the perceived quality by the customer (QoE) needs to be monitored by estimation. For that, the streaming video quality needs to be measured and monitored permanently. For TCP based progressive download we propose to extract the the video timestamps which are encoded within the payload of the TCP segments by decoding the video within the payload. The actual estimation is then done by play out buffer fill level calculations based on the TCP segment timestamp and their internal play out timestamp. The perceived quality for the user is derived from the number and duration of video stalls. Algorithms for decoding Flash Video, MP4 and WebM Video have already been implemented. After deriving the play out time it is compared to the timestamp of the respective TCP segment. The result of this comparison is an estimate of the fill level of the play out buffer in terms of play out time within the client. This estimation is done without access to the end device. The same measurement procedure can be applied for any TCP based progressive download Internet service. Video was simply taken as an example because of its current large share in traffic volume in operator networks.

E-business systems provide the infrastructure whereby parties interact electronically via business transactions. At peak loads, these systems are susceptible to large volumes of transactions and concurrent users and yet they are expected to maintain adequate performance levels. Over provisioning is an expensive solution. A good alternative is the adaptation of the system, managing and controlling its resources. We address these concerns by presenting a model that allows fast evaluation of performance metrics in terms of measurable or controllable parameters. The model can be used in order to (a) predict the performance of a system under given or assumed loading conditions and (b) to choose the optimal configuration set-up for certain controllable parameters with respect to specified performance measures. Firstly, we analyze the characteristics of E-business systems. This analysis leads to the analytical model, which is sufficiently general to capture the behaviour of a large class of commonly encountered architectures. We propose an approximate solution which is numerically efficient and fast. By mean of simulation, we prove that its accuracy is acceptable over a wide range of system configurations and different load levels. We further evaluate the approximate solution by comparing it to a real-life E-business system. A J2EE application of non-trivial size and complexity is deployed on a 2-tier system composed of the JBoss application server and a database server. We implement an infrastructure fully integrated on the application server, capable of monitoring the E-business system and controlling its configuration parameters. Finally, we use this infrastructure to quantify both the static parameters of the model and the observed performance. The latter are then compared with the metrics predicted by the model, showing that the approximate solution is almost exact in predicting performance and that it assesses the optimal system configuration very accurately.

With the rising popularity of Voice over IP (VoIP) services, understanding the effects of a global network on Quality of Service is critical for the providers of VoIP applications. This thesis builds on a model that analyzes the round trip time, packet delay jitter, and packet loss between endpoints on an Autonomous System (AS) level, extending it by mapping AS pairs onto an Internet topology. This model is used to produce a mean opinion score estimate. The mapping is introduced to reduce the size of the problem in order to improve computation times and improve accuracy of estimates. The results of testing show that estimating mean opinion score from this model is not desirable. It also shows that the path mapping does not affect accuracy, but does improve computation times as the input data grows in volume.

Le schéma de modulation OFDM est très répandu de nos jours (WiFi, WiMAX, \dots) et préconisé comme couche physique pour de nombreux réseaux futurs (3GPP/LTE, IEEE 802.22). Ainsi cette coexistence de réseaux OFDM fait que l'environnement radio est de nos jours hétérogène. Afin de tirer partie de cette hétérogénéité et de satisfaire le concept de ''\textit{Always Best connected}'', il a été imaginé des terminaux multistandards capables de basculer de manière transparente d'un réseau à un autre à la recherche du réseau offrant la qualité de service la plus satisfaisante. Ce processus de basculement entre standards est appelé ''\textit{vertical handover}''. Avant de déclencher un \textit{vertical handover} le terminal se doit d'identifier les réseaux actifs qui l'entourent et estimer la qualité de service disponible sur chaque réseau. Ainsi, dans le cadre de cette thèse nous proposons dans un premier temps des algorithmes d'identification de systèmes OFDM. Dans un second temps, nous nous intéressons à la qualité de service disponible sur les réseaux détectés, nous avons ainsi proposé des estimateurs de métriques de qualité de service dédiés à des réseaux basés sur les schémas d'accès multiples OFDMA et CSMA/CA. Certaines de ces métriques ont été validées expérimentalement sur la plate-forme RAMMUS de TELECOM Bretagne. Toutes les techniques proposées dans le cadre de cette thèse, sont des approches passives à faible coût de calcul qui ne nécessitent aucune connexion au point d'accès, permettant ainsi une économie en temps et en énergie.

Objective quality evaluation is a key element for the success of the emerging Voice over IP (VoIP) technologies. Although there are extensive economic incentives for the convergence of voice, data, and video networks, packet networks such as the Internet have inherent incompatibilities with the transport of real time services. Under this paradigm, network planners and administrators are interested in ongoing mechanisms to measure and ensure the quality of these real time services. Objective quality assessment algorithms can be broadly divided into a) intrusive (methods that require a reference signal), and b) non intrusive (methods that do not require a known reference signal). The latter group, typically requires knowledge of the network conditions (level of delay, jitter, packet loss, etc.), and that has been a very active area of research in the past decade. The state of the art methods for objective non-intrusive quality assessment provide high correlations with the subjective tests. Although good correlations have been achieved already for objective non-intrusive quality assessment, the current large voice transport networks are in a hybrid state, where the necessary network parameters cannot easily be observed from the packet traffic between nodes. This thesis proposes a new process, the Network Conditions Estimator (NCE), which can serve as bridge element to real-world hybrid networks. Two classifications systems, an artificial neural network and a C4.5 decision tree, were developed using speech from a database collected from experiments under controlled network conditions. The database was composed of a group of four female speakers and three male speakers, who conducted unscripted conversations without knowledge about the details of the experiment. Using mel frequency cepstral coefficients (MFCCs) as the feature-set, an accuracy of about 70% was achieved in detecting the presence of jitter or packet loss on the channel. This resulting classifier can be incorporated as an input to the E-Model, in order to properly estimate the QoS of a network in real time. Additionally, rather than just providing an estimation of subjective quality of service provided, the NCE provides an insight into the cause for low performance.

Several heterogeneous, intelligent and distributed devices can be connected to interact with one another over the internet in what is known as the internet of things (IoT). Also, the concept of IoT can be exploited in the industrial environment for increasing the production output of goods and services and for mitigating the risk of disaster occurrences. This application of IoT for enhancing industrial production is known as industrial IoT (IIoT). More so, the benefits of IoT technology can be particularly exploited across the maritime industry in what is termed the internet of maritime things (IoMT) where sensors and actuator devices are implanted on marine equipment in order to foster the communication efficacy of nautical radio networks. Marine explorations may suffer from unwanted situations such as transactional delays, environmental degradation, insecurity, seaport congestions, accidents and collisions etc, which could arise from severe environmental conditions. As a result, there is a need to develop proper communication techniques that will improve the overall quality of service (QoS) and quality of experience (QoE) of marine users. To address these, the merits of contemporaneous technologies such as ubiquitous computing, software-defined networking (SDN) and network functions virtualization (NFV) in addition to salubrious communication techniques including emergent configurations (EC), channel estimation (CE) and communication routing protocols etc, can be utilized for sustaining optimal operation of pelagic networks. Emergent configuration (EC) is a technology that can be adapted into maritime radio networks to support the operation and collaboration of IoT connected devices in order to improve the efficiency of the connected IoT systems for maximum user satisfaction. To meet user goals, the connected devices are required to cooperate with one another in an adaptive, interoperable, and homogeneous manner. In this thesis, a survey on the concept of IoT is presented in addition to a review of IIoT systems. The applications of ubiquitous computing and SDN technology are employed to design a newfangled network architecture which is specifically propounded for enhancing the throughput of oil and gas production in the maritime ecosystem. The components of this architecture work in collaboration with one another by attempting to manage and control the exploration process of deep ocean activities especially during emergencies involving anthropogenic oil and gas spillages. Several heterogeneous, intelligent and distributed devices can be connected to interact with one another over the internet in what is known as the internet of things (IoT). Also, the concept of IoT can be exploited in the industrial environment for increasing the production output of goods and services and for mitigating the risk of disaster occurrences. This application of IoT for enhancing industrial production is known as industrial IoT (IIoT). More so, the benefits of IoT technology can be particularly exploited across the maritime industry in what is termed the internet of maritime things (IoMT) where sensors and actuator devices are implanted on marine equipment in order to foster the communication efficacy of nautical radio networks. Marine explorations may suffer from unwanted situations such as transactional delays, environmental degradation, insecurity, seaport congestions, accidents and collisions etc, which could arise from severe environmental conditions. As a result, there is a need to develop proper communication techniques that will improve the overall quality of service (QoS) and quality of experience (QoE) of marine users. To address these, the merits of contemporaneous technologies such as ubiquitous computing, software-defined networking (SDN) and network functions virtualization (NFV) in addition to salubrious communication techniques including emergent configurations (EC), channel estimation (CE) and communication routing protocols etc, can be utilized for sustaining optimal operation of pelagic networks. Emergent configuration (EC) is a technology that can be adapted into maritime radio networks to support the operation and collaboration of IoT connected devices in order to improve the efficiency of the connected IoT systems for maximum user satisfaction. To meet user goals, the connected devices are required to cooperate with one another in an adaptive, interoperable, and homogeneous manner. In this thesis, a survey on the concept of IoT is presented in addition to a review of IIoT systems. The applications of ubiquitous computing and SDN technology are employed to design a newfangled network architecture which is specifically propounded for enhancing the throughput of oil and gas production in the maritime ecosystem. The components of this architecture work in collaboration with one another by attempting to manage and control the exploration process of deep ocean activities especially during emergencies involving anthropogenic oil and gas spillages. On the other hand, CE is a utilitarian communication technique that can be exploited during maritime exploration processes which offer additional reinforcement to the capacities of the nautical radio network. This technique enables the receivers of deep-sea networks to efficiently approximate the channel impulse response (CIR) of the wireless communication channel so that the effects of the communication channel on the transmitting aggregated cluster head information can be proficiently understood and predicted for useful decision-making procedures. Two CE schemes named inter-symbol interference/ average noise reduction (ISI/ANR) and reweighted error-reducing (RER) are designed in this study for estimating maritime channels for supporting the communication performances of nautical radio networks in both severe and light-fading environmental conditions. In the proposed RER method, the Manhattan distance of the CIR of an orthodox adaptive estimator is taken, which is subsequently normalised by a stability constant ɛ whose responsibility is for correcting any potential numerical system instability that may arise during the updating stages of the estimation process. To decrease the received signal error, a log-sum penalty function is eventually multiplied by an adjustable leakage (ɛ ) ̈that provides additional stability to the oscillating channel behaviour. The performance of the proposed RER method is further strengthened and made resilient against channel effects by the introduction of a reweighting attractor that further contracts the mean square error of this proposed estimator. In the ISI/ANR technique, the effects of possible ISI that may arise from maritime transmissions is considered and transformed using a low-pass filter that is incorporated for eliminating the effects of channel noise possible effects of multipath propagation. The RER scheme offered superior CE performances in comparison to other customary techniques such as the adaptive recursive least squares and normalised least mean square method in addition to conventional linear approaches such as least squares, linear minimum mean square error and maximum-likelihood estimation method. The proposed ISI/ANR technique offered an improved MSE performance in comparison to all considered linear methods. Finally, from this study, we were able to establish that accurate CE methods can improve the QoS and QoE of nautical radio networks in terms of network data rate and system outage probability.
Thesis (PhD (Computer Engineering))--University of Pretoria, 2021.
University of Pretoria Doctoral research grant, South African National Research Foundation/Research and Innovation Support and Advancement (NRF/RISA) research grant. Center for Connected Intelligence, Advanced Sensor Networks research group, University of Pretoria.
Electrical, Electronic and Computer Engineering
PhD (Computer Engineering)
Unrestricted

Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2005. Directed by John Copeland.
Copeland, John, Committee Chair ; Owen, Henry, Committee Member ; Sivakumar, Raghupathy, Committee Member ; Lanterman, Aaron, Committee Member ; Dos Santos, Andre, Committee Member. Includes bibliographical references.

La téléopération en réseau est une thématique émergente, où un humain (le maître) communique avec un esclave commandé à distance à travers un réseau de communication, pour l'échange des données de commande et de mesure. Pour la téléopération longue distance, ces informations traversent divers réseaux hétérogènes ou hybrides interconnectés ensemble. Nous traitons également le cas où un segment sera sans fil, ce qui permet d'envisager que l'esclave soit mobile (véhicule télé-opéré par exemple). Une étude indépendante des aspects commande et des aspects réseau entraîne l'atteinte d'objectifs locaux, qui peuvent le cas échéant être ensuite fortement dégradés après l'intégration des deux aspects. L'utilisation de réseaux partagés, comme internet, en lieu et place d'une liaison dédiée (point à point, liaison virtuelle) est également un défi, en particulier dans le cas de la longue distance. Les mécanismes de qualité de service (QdS) d'un réseau, en particulier du réseau hétérogène, doivent pouvoir être traités par les autres réseaux ; ces points sont assez souvent traités avec un point de vue d'applications multimedia, plus rarement avec le point de vue de la téléopération critique. L'approche de téléopération en réseau peut profiter de ces mécanismes de qualité de service en utilisant des priorités ou des réservations de bandes passantes en fonction des critères de commande et de transparence. Cela peut entraîner une adaptation des ressources réseau en fonction des besoins des objectifs de téléopération afin de transporter l'information en satisfaisant les besoins bout en bout de l'application, cette notion devant être précisée. Lorsqu'on considère la QdS avec un point de vue réseau, elle consiste principalement à la gestion de flux de communication, en prenant en compte des paramètres de besoin et d'ordonnancement. Si l'on prend en compte le point de vue de la téléopération, la QdS entraîne des conséquences sur la qualité de commande (QdC) ce qui inclut la stabilité, la transparence et la téléprésence. De plus, l'interface humaine peut également avoir des besoins spécifiques en termes de téléprésence, ce qui peut entraîner des conséquences sur la répartition de la charge du réseau. Afin d'intégrer les deux approches de QdS et de QdC pour apporter une meilleure réponse au problème posé, nous proposons une approche de coconception avec d'une part une adaptation de la QdS aux besoins de la Qdc (qualité de la transparence) et d'autre part une adaptation de la Qdc (par exemple dégradation de la qualité du flux vidéo) à la disponibilité du réseau. Nous avons considéré deux cas de figures. Dans un premier temps, sans tenir compte des mécanismes de QdS du réseau (approche dite du meilleur effort ou best effort) et par l'adaptation au mieux de l'application, pour répondre aux besoins de la téléopération. La seconde approche considère un réseau orienté QdS entre le maître et l'esclave, où différentes priorités peuvent être attribuées aux flux nécessaires à la téléopération, en fonction des contextes. L'approche proposée est finalement mise en oeuvre sur NeCS-Car, la voiture téléopérée disponible au Laboratoire
Networked teleoperation (NT) is an emerging area of technology, where human assisted Master and remote Slave devices communicate over a communication network for the exchange of command and sensor feedback information. For long range mobile teleoperation, this information travels over different types of heterogeneous/hybrid networks interconnected together with a compulsory network segment over wireless to permit increased mobility. The independent design of control and network promotes the isolated objectives and the performance is degraded after an integration. It is also challenging if internet is used for teleoperation, instead of point to point communication. The mechanisms of QoS in one network protocol of the heterogeneous network needs mapping on any other network which is usually carried out with a multimedia point of view and not for the critical teleoperation data. The approach for networked teleoperation can be given a new dimension by adding quality of service (QoS) to different flows on need based priority and as a function of control and transparence criteria. This means to alter the network resources for teleoperation objective in order to transport the information to satisfy the end-to-end application needs. The network QoS perspective is important to consider in the co-design approach for teleoperation. However, the true meaning of end to end QoS must be defined for teleoperation. If we consider the QoS from the network point of view, it refers to the management of various flows or users as per their need and precedence. Whereas, from the teleoperation perspective, QoS is related to the quality of control (QoC) which includes stability, transparence and telepresence. Moreover, the human interface may have different requirements as per telepresence feeling which will result in varying network load. To control network QoS, we need to measure or estimate it. Therefore, classification of QoS is performed with a fuzzy inference system which is able to distinguish between varying levels of QoS. In addition, it is also a challenging task for online decision for reconfiguration of network and control performance. We have used supervised methods for classification and prediction of QoS to be used in the proposed approach. Thus, data communication networks treat control information as best effort most of the time. Conclusion the communication used in teleoperation uses a dedicated network/communication. In short, a co-design approach is formulated to treat the network QoS as a function of teleoperation objectives which are related to the quality of transparence and control. Alternatively, the video flow is managed in order to effectively reduce the necessary throughput for instants when the network quality is not sufficient. We have considered two cases. First, without taking into account any network QoS mechanism (best effort flows only) and adapting application needs as per the teleoperation objectives. The second one considers a QoS oriented network in between the master and slave, where different priorities can be assigned to the teleoperation flows as per need. In the end, the proposed methodology is implemented on the NeCS-Car benchmark

Les travaux de recherche présentés dans cette thèse portent sur la Qualité de Service (QoS) et l'allocation de ressources dans les réseaux UMTS-TDD. Les réseaux UMTS se composent de deux parties, une partie filaire qui peut être sous IP et peut utiliser Diffserv pour la gestion de la QoS, et une partie réseau d'accès radio (UTRAN) qui gère la transmission sur la partie radio. Nous avons d'abord proposé une méthode de transcription de la QoS Diffserv en QoS UMTS. Ensuite, nous avons réalisé une étude du comportement de l'UTRAN en fonction de l'état du canal radio. Cette étude a permis d'évaluer les délais de transmission, les taux de pertes et l'efficacité de différents paramétrages et ainsi de proposer un paramétrage de l'UTRAN adapté aux besoins de chaque type d'application. Nous avons également proposé un mécanisme de lien adaptatif qui permet d'accroître l'efficacité de notre système. Puis nous avons proposé un algorithme d'allocation en relation avec l'algorithme de contrôle d'accès pour les applications de type Temps Réel (RT). Cet algorithme permet d'indiquer les ressources attribuées à un utilisateur et d'équilibrer la puissance de transmission sur les différents slots ce qui accroît le nombre d'utilisateurs qui peuvent être présents simultanément. Pour le trafic Non Temps Réels (NRT) nous avons appliqué une politique d'ordonnancement qui préempte des flux en fonction de l'état du canal tout en restant équitable sur le long terme. Cet ordonnancement réduit le BLER. L'ordonnancement est couplé au contrôle d'accès, l'utilisation d'une ressource par du trafic NRT ne détériore pas le service du trafic RT au delà d'un certain seuil
The UMTS networks, third-generation mobile networks, will support high-speed multimedia services. This thesis concerns the UMTS-TDD with a radio access sub-system (UTRAN) directly connected to IPv6. The whole QoS is managed by the DiffServ protocol mechanisms. First, we propose a mechanism to map the DiffServ QoS to a UMTS DiffServ. Then, from this UMTS QoS, we propose a parameter tuning with respect to the QoS required by the applications that respects the delays and loss criteria. When several parameters tuning sche were possible, we selected the parameter that maximizes the system efficiency. Knowing that the most efficient parameter changes within channel characteristics, we have proposed and evaluated an adaptive tuning scheme that maximizes this efficiency. Then, we have considered a system combining Real-Time (RT) and Non Real-Time applications (NRT). In order to maintain the current applications QoS, we have applied an access control and resources allocation mechanism to the RT applications. The access control does not accept an application if there is not enough available resources or if the use of necessary resources for the new application will exceed a power threshold. The resources allocation mechanism allows by an appropriate (codes, power) combination, to decrease the amount of rejected real-time applications. Concerning the NRT applications, we propose a scheduling mechanism. It takes into account the channel state to select a flow. This will decrease the BLER. The scheduling is fair in the long term. Furthermore, the scheduling algorithm is linked to the access control in order to mix NRT and RT applications efficently

While there has always been a tremendous demand for streaming video over Wireless networks, the nature of the application still presents some challenging issues. These applications that transmit coded video sequence data over best-effort networks like the Internet, the application must cope with the changing network behaviour; especially, the source encoder rate should be controlled based on feedback from a channel estimator that explores the network intermittently. The arrival of powerful video compression techniques such as H.264, which advance in networking and telecommunications, opened up a whole new frontier for multimedia communications. The aim of this research is to transmit the H.264 coded video frames in the wireless network with maximum reliability and in a very efficient manner. When the H.264 encoded video sequences are to be transmitted through wireless network, it faces major difficulties in reaching the destination. The characteristics of H.264 video coded sequences are studied fully and their capability of transmitting in wireless networks are examined and a new approach called Optimal Packet Fragmentation (OPF) is framed and the H.264 coded sequences are tested in the wireless simulated environment. This research has three major studies involved in it. First part of the research has the study about Long Range Dependence (LRD) and the ways by which the self-similarity can be estimated. For estimating the LRD a few studies are carried out and Wavelet-based estimator is selected for the research because Wavelets incarcerate both time and frequency features in the data and regularly provides a more affluent picture than the classical Fourier analysis. The Wavelet used to estimate the self-similarity by using the variable called Hurst Parameter. Hurst Parameter tells the researcher about how a data can behave inside the transmitted network. This Hurst Parameter should be calculated for a more reliable transmission in the wireless network. The second part of the research deals with MPEG-4 and H.264 encoder. The study is carried out to prove which encoder is superior to the other. We need to know which encoder can provide excellent Quality of Service (QoS) and reliability. This study proves with the help of Hurst parameter that H.264 is superior to MPEG-4. The third part of the study is the vital part in this research; it deals with the H.264 video coded frames that are segmented into optimal packet size in the MAC Layer for an efficient and more reliable transfer in the wireless network. Finally the H.264 encoded video frames incorporated with the Optimal Packet Fragmentation are tested in the NS-2 wireless simulated network. The research proves the superiority of H.264 video encoder and OPF's master class.

Ce manuscrit est centré sur la conception, l'amélioration et l'évaluation des protocoles des couches RESEAU, MAC et PHY. En particulier, nous nous focalisons sur la conception de nouveaux protocoles distribués pour une utilisation optimale/améliorée des ressources radio disponibles. Par ailleurs, nous caractérisons les performances des réseaux ad hoc à accès aléatoire au canal en utilisant des paramètres de plusieurs couches avec aptitude de transfert d'information (data forwarding). La majeure partie de nos analyses se base sur le concept d'interaction entre les couches OSI (cross-layer). En effet, cette nouvelle et attractive approche est devenue en peu de temps omniprésente dans le domaine de recherche et développement et dans le domaine industriel. Les métriques de performances qui nous intéressent sont la stabilité des files d'attentes de transfert, le débit, le délai et la consommation d'énergie. Principalement, la compréhension de l'interaction entre les couches MAC/PHY et routage du standard IEEE 802.11e DCF/EDCF, d'une part, et l'interaction entre noeuds en terme d'interférences, d'autre part, constituent le coeur central de notre travail

La forte variabilité des trafics est devenue l'un des problèmes majeurs auxquels doivent faire face les gestionnaires d'infrastructures réseau. Dans ces conditions, l'optimisation du routage des flux en se basant uniquement sur une matrice de trafic moyenne estimée en heure de pointe n'est plus pertinente. Les travaux conduits dans cette thèse visent la conception de méthodes d'optimisation dynamiques du routage, adaptant en temps réel les routes utilisées par les flux aux conditions de trafic dans le réseau.Nous étudions tout d'abord le problème d'optimisation des poids OSPF pour le routage intra-domaine dans les réseaux IP, où le trafic est routé le long de plus courts chemins, en fonction des poids des liens. Nous proposons une approche en ligne permettant de reconfigurer dynamiquement les poids OSPF, et donc les routes utilisées, pour répondre aux variations observées du trafic et réduire ainsi le taux de congestion du réseau. L'approche proposée repose sur l'estimation robuste des demandes en trafic des flux à partir de mesures SNMP sur la charge des liens. Les résultats expérimentaux, aussi bien sur des trafics simulés que réels, montrent que le taux de congestion du réseau peut être significativement réduit par rapport à une configuration statique.Dans la même optique, nous nous intéressons également à l'optimisation des réseaux MPLS, qui permettent de gérer l'utilisation des ressources disponibles en affectant un chemin spécifique à chaque LSP. Nous proposons un algorithme inspiré de la théorie des jeux pour déterminer le placement des LSP optimisant un critère de performance non linéaire. Nous établissons la convergence de cet algorithme et obtenons des bornes sur son facteur d'approximation pour plusieurs fonctions de coût. L'intérêt principal de cette technique étant d'offrir des solutions de bonne qualité en des temps de calcul extrêmement réduits, nous étudions son utilisation pour la reconfiguration dynamique du placement des LSP.La dernière partie de cette thèse est consacrée à la conception et au développement d'une solution logicielle permettant le déploiement d'un réseau overlay auto-guérissant et auto-optimisant entre différentes plateformes de cloud computing. La solution est conçue pour ne nécessiter aucun changement des applications. En mesurant régulièrement la qualité des liens Internet entre les centres de données, elle permet de détecter rapidement la panne d'une route IP et de basculer le trafic sur un chemin de secours. Elle permet également de découvrir dynamiquement les chemins dans le réseau overlay qui optimisent une métrique de routage spécifique à l'application. Nous décrivons l'architecture et l'implémentation du système, ainsi que les expériences réalisées à la fois en émulation et sur une plateforme réelle composée de plusieurs centres de données situés dans différents pays
The high variability of traffic has become one of the major problems faced by network infrastructure managers . Under these conditions, flow route optimization based solely on an average busy hour traffic matrix is no longer relevant. The work done in this thesis aims to design dynamic routing optimization methods, adapting in real time the routes used by the flows to the actual network traffic conditions.We first study the problem of OSPF weight optimization for intra-domain routing in IP networks, where the traffic is routed along shortest paths, according to links weights. We propose an online scheme to dynamically reconfigure the OSPF weights and therefore the routes used, to respond to observed traffic variations and reduce the network congestion rate. The proposed approach is based on robust estimation of flow traffic demands from SNMP measurements on links loads. Experimental results, both on simulated and real traffic data show that the network congestion rate can be significantly reduced in comparison to a static weight configuration.On the same idea, we are also interested in optimizing MPLS networks that manage the available resource utilization by assigning a specific path for each LSP. We propose an algorithm inspired by game theory to determine the LSP placement optimizing a nonlinear performance criterion. We establish the convergence of the algorithm and obtain bounds on its approximation factor for several cost functions. As the main advantage of this technique is to offer good quality solutions in extremely reduced computation times, we are studying its use for dynamic reconfiguration of the LSP placement.The last part of this thesis is devoted to the design and development of a software solution for the deployment of a self-healing and self-optimizing network overlay between different cloud platforms. The solution is designed such that no change is required for client applications. By regularly measuring the quality of Internet links between data centers, it can quickly detect an IP route failure and switch the traffic to a backup path. It also allows to dynamically discover the paths in the overlay network that optimize a routing metric specific to the application. We describe the system architecture and implementation, as well as the experiments in both emulation and real platform composed of several data centers located in different countries

Immersive applications, such as computer gaming, computer vision and video codecs, are an important emerging class of applications with QoS requirements that are difficult to characterize and control using traditional methods. This thesis proposes new techniques reliant on execution-time variance to both characterize and control program behavior. The proposed techniques are intended to be broadly applicable to a wide variety of immersive applications and are intended to be easy for programmers to apply without needing to gain specialized expertise. First, we create new QoS controllers that programmers can easily apply to their applications to achieve desired application-specific QoS objectives on any platform or application data-set, provided the programmers verify that their applications satisfy some simple domain requirements specific to immersive applications. The controllers adjust programmer-identified knobs every application frame to effect desired values for programmer-identified QoS metrics. The control techniques are novel in that they do not require the user to provide any kind of application behavior models, and are effective for immersive applications that defy the traditional requirements for feedback controller construction. Second, we create new profiling techniques that provide visibility into the behavior of a large complex application, inferring behavior relationships across application components based on the execution-time variance observed at all levels of granularity of the application functionality. Additionally for immersive applications, some of the most important QoS requirements relate to managing the execution-time variance of key application components, for example, the frame-rate. The profiling techniques not only identify and summarize behavior directly relevant to the QoS aspects related to timing, but also indirectly reveal non-timing related properties of behavior, such as the identification of components that are sensitive to data, or those whose behavior changes based on the call-context.

The tremendous increase in data traffic has spurred a rapid evolution of the optical networks for a reliable, affordable, cost effective and scalable network infrastructure. To meet some of these requirements, network operators are pushing toward disaggregation. Network disaggregation focuses on decoupling the traditional monolithic optical transport hardware into independent functional blocks that interoperate. This enables a relatively free market where the network operators/owners could choose the best-in-class equipment from different vendors overcoming the vendor lock-in, at better prices. In this multi-vendor disaggregation context, the used equipment would impact the physical layer and the overall network behavior. This results in increasing the uncertainty on the performance when compared to a traditional single vendor aggregated approach. For effective optical network planning, operation and optimization, it is necessary to estimate the Quality of Transmission (QoT) of the connections. Network designers are interested in accurate and fast QoT estimation for services to be established in a future or existing network. Typically, QoT estimation is performed using a Physical Layer Model (PLM) which is included in the QoT estimation tool or Qtool. A design margin is generally included in a Qtool to account for the modeling and parameter inaccuracies, to re-assure an acceptable performance. PLM accuracy is highly important as modeling errors translate into a higher design margin which in turn translate into wasted capacity or unwanted regeneration. Recently monitoring and machine learning (ML) techniques have been proposed to account for the actual network conditions and improving the accuracy of the PLM in single vendor networks. This in turn results in more accurate QoT estimation. The first part of the thesis focuses on the ML assisted accurate QoT estimation techniques. In this regard, we developed a model that uses monitoring information from an operating network combined with supervised ML regression techniques to understand the network conditions. In particular, we model the generated penalties due to i). EDFA gain ripple effect, and ii). filter spectral shape uncertainties at ROADM nodes. Furthermore, with the aim of improving the Qtool estimation accuracy in multi-vendor networks, we propose PLM extensions. In particular, we introduce four TP vendor dependent performance factors that capture the performance variations of multi-vendor TPs. To verify the potential improvement, we studied the following two use cases with the proposed PLM, to: i) optimize the transponders (TPs) launch power; and ii) reduce design margin in incremental planning. In consequence, the last part of this thesis aims at investigating and solving the issue of accuracy limitation of Qtool in dynamic optimization tasks. To keep the models aligned to the real conditions, the digital twin (DT) concept is gaining significant attention in the research community. The DT is more than a model of the system; it includes an evolving set of data, and a means to dynamically adjust the model. Based on the DT fundamentals, we devised and implemented an iterative closed control loop process that, after several intermediate iterations of the optimization algorithm, configures the network, monitors, and retrains the Qtool. For the Qtool retraining, we adopt a ML-based nonlinear regression fitting technique. The key advantage of this novel scheme is that whilst the network operates, the Qtool parameters are retrained according to the monitored information with the adopted ML model. Hence, the Qtool tracks the projected states intermediately calculated by the algorithm. This reduces the optimization time as opposed to directly probing and monitoring the network.
Las operadoras están impulsando el concepto de desagregación de red. Dicho concepto permite desacoplar el tradicional hardware de transporte óptico dispuesto de forma monolítica en bloques funcionales independientes que interoperan entre ellos. Como resultado, esta desagregación incentiva un mercado más abierto en el cual los operadores/propietarios de la red pueden elegir los mejores dispositivos de diferentes proveedores, eliminando el conocido como bloqueo/dependencia del proveedor, a precios más competitivos. En este contexto de desagregación con múltiples fabricantes, cada equipo afecta de forma independiente. Por lo tanto, la incertidumbre aumenta al compararlo con el rendimiento obtenido mediante un modelo más tradicional basado en agregación y dependiente de un único proveedor. Para una eficiente planificación y optimización de una red óptica, es necesario estimar la Quality of Transmission (QoT) de las conexiones. Los diseñadores de redes están interesados en una estimación precisa y rápida de la QoT para los servicios que se establezcan. Normalmente, la estimación de la QoT se realiza mediante un Physical Layer Model (PLM) que se incluye en la herramienta de estimación de la QoT o Qtool. Además, se incluye unos márgenes de diseño (design margin) dentro de la herramienta Qtool. Esto permite tener en cuenta las imprecisiones de modelado y de los parámetros y de esta forma asegurar un rendimiento aceptable. La precisión del PLM es muy importante, ya que los errores de modelado se traducen en un mayor design margin que, a su vez, se traduce en una pérdida de capacidad. Recientemente, importantes logros en la definición de PLMs para redes ópticas más precisos y rápidos se han alcanzado. Estos se basan en métodos tradicionales con soluciones analíticas o numéricas. La primera parte de la tesis se centra en las técnicas de estimación precisa de QoT asistidas por machine learning (ML). Se ha desarrollado un modelo que utiliza la información de monitorización de red combinada con técnicas de regresión ML supervisadas para comprender las condiciones de la red. En particular, se han modelado las penalizaciones generadas debido a: i) el efecto de gain ripple del EDFA, y ii) las incertidumbres de la forma espectral del filtro en los nodos ROADM. Además, con el objetivo de mejorar la precisión de la estimación del Qtool en redes que incluyen elementos de diferentes fabricantes (i.e., multi-proveedor), se han propuesto unas extensiones del PLM. Se han introducido cuatro factores de rendimiento dependientes del proveedor del transponder (TP) que capturan las variaciones de rendimiento de los TP de múltiples proveedores. Para verificar la mejora potencial, se han estudiado los siguientes dos casos de uso con el PLM propuesto: i) optimizar la potencia de lanzamiento de los TPs; y ii) reducir el design margin. La última parte de esta tesis ha tenido como objetivo investigar la cuestión de la limitación de la precisión del Qtool en las tareas de optimización dinámica. Para mantener los modelos alineados con las condiciones reales, el concepto de digital twin (DT) está ganando mucha atención. El DT incluye un conjunto de datos en evolución y un medio para ajustar dinámicamente el modelo. Basándonos en los fundamentos del DT, se ha ideado e implementado un proceso iterativo de bucle cerrado de control que, tras varias iteraciones intermedias del algoritmo de optimización, configura la red, supervisa y reentrena el Qtool. Para el reentrenamiento del Qtool, se ha adoptado una técnica de ajuste de regresión no lineal basada en ML. La principal ventaja es que, mientras la red funciona, los parámetros del Qtool se reentrenan según la información monitorizada con el modelo ML adoptado. Por lo tanto, el Qtool sigue los estados proyectados de forma intermedia calculados por el algoritmo. Esto reduce el tiempo de optimización en comparación con el sondeo y la monitorización directa
Teoria del senyal i comunicacions

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This paper presents a model based on Markov Chains and enhanced with the use of Kernel Density Estimation and of MMFM (Markov Modulated Fluid Model) in order to evaluate the performance of the transmission link in OFDMTDMA systems. For that purpose, traffic models based on the Kernel method and the MMFM with adjusted autocorrelation function are proposed. From the model implemented for the OFDM-TDMA system, it was derived equations for estimation of QoS parameters such as delay and average queue size in the buffer. The obtained results confirm that the proposed model is efficient in describing the link performance indicators. The use of MMFM to model the arrival process improves the QoS parameter estimates of the queueing model making their values very close to those of the simulation results. It was also developed an equation to the OFDMTDMA system’s service curve. Through this equation and the concept of Envelope Process, it was proposed an equation to estimate the probability of buffer overflow in OFDM-TDMA systems. The results show that the estimates of the overflow probability based on the system’s service curve are very close to the ones obtained by simulations and that the computational complexity to obtain them is significantly reduced compared to the model based on Markov Chains due to the absence of matrix computation.
Este trabalho apresenta um modelo baseado em Cadeias de Markov e aprimorado com o uso do método de Kernel de estimação não-paramétrica e de MMFM (Markov Modulated Fluid Model) com o objetivo de avaliar e descrever o desempenho do enlace de transmissão em sistemas OFDM-TDMA. Para tal, modelos de tráfego baseados no Método de Kernel e em MMFM com ajuste da função de autocorrelação são propostos. A partir do modelo implementado para o sistema OFDM-TDMA, foram obtidas equações para estimação de parâmetros de QoS como retardo e tamanho médio da fila no buffer. Os resultados obtidos confirmam que o modelo proposto é bastante eficiente ao descrever os indicadores de desempenho do sistema. O uso de MMFM para modelar o processo de chegada de pacotes aprimora os estimadores de parâmetros de QoS tornando as estimativas bem próximas dos valores obtidos com as simulações. Também deduziu-se uma equação para a curva de serviço de Sistemas OFDM-TDMA. Em seguida, utilizando-se desta curva de serviço e do conceito de Processo Envelope foi proposta uma equação para estimação de probabilidade de transbordo do buffer em sistemas OFDM-TDMA. Os resultados obtidos mostram que as estimativas de probabilidade de transbordo baseadas na curva de serviço do sistema se aproximam bem dos resultados da simulação e a complexidade computacional do cálculo necessário para obtê-los é significativamente reduzida em relação ao modelo definido utilizando Cadeias de Markov.

Background: In the recent years, the focus of research has shifted to Quality of Experience(QoE) to maintain the user satisfaction levels and fulfill their expectations of the serviceoffered. Numerous work has been established in finding the relationship between the networklayer and QoE. But, it is fact that the transport layer is much closer to the end-user than thenetwork layer in the TCP/IP communication protocol suite. Thus, any changes in the degreeof satisfaction or degree of annoyance are directly reflected onto transport layer than on thenetwork layer. So, it becomes more significant to study the behavior of user satisfaction inrelation to transport layer than the network layer. Objectives: This research is to relate the behavior of TCP to QoE. The main considerations tobridge the gap between them are: (a) Analyzing the effects of using different versions of TCPon server and client side, (b) Monitoring and analyzing the intensity of TCP traffic in thereverse direction and (c) Investigating TCP control flags from client to server. Methods: QoE related parameters used in this research are: (a) Quality of video i.e., MOS, (b)Degree of disturbance caused by initial delay, (c) Degree of disturbance caused by jerkinessand (d) Degree of disturbance caused by freezes. Effects of network impairments like delay,jitter and packet loss are considered in this research. NetEm is used as the traffic emulationsoftware to shape the traffic. The packet capture analysis of traffic exchange is implementedusing tcpdump. Results and Conclusions: The aim of this research is to provide a passive-estimation methodto assess the user perceived performance. The results of this research provide valuablecontribution to service providers/operators to note the early warning signals from TCP reversetraffic to evaluate the decrease of user satisfaction level and try to cope or/and recover fromimpairments in the network. This research also provides a scope for future researchers toinvestigate other protocols both in transport and application layers.

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CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
O advento de novas formas multimídia tem atraído uma clientela exigente, onde preocupação não é somente com o serviço, mas também, com a qualidade que esse serviço pode ser oferecido. As WLAN (Wireless Local Area Networks) tornaram-se a forma mais comum de roteamento de Internet, devido ao seu baixo custo e facilidade de implementação. Para realizar um bom roteamento é necessário um planejamento, utilizando-se modelos. Os modelos de propagação existentes na literatura fazem a predição da intensidade do sinal, mas algumas vezes não contemplam a previsão de um bom serviço. Nesse sentido a presente dissertação propõe-se a elaborar um modelo de propagação empírico indoor multi-andar que não só prediz a potência recebida, mas também faz uma previsão para algumas métricas de QoS (Quality of Service) de chamadas VoIP (Voice over Internet Protocol). Para a elaboração do modelo proposto foram feitas campanhas de medição, em um prédio de dois andares, em pisos distintos mantendo-se a posição do ponto de acesso (PA) fixa. Estudos de geometria analítica para a contagem e agregação de perdas em pisos e paredes. Os resultados do modelo proposto foram comparados com um modelo da literatura que tem um comportamento similar, onde é possível verificar o melhor desempenho do modelo proposto, e para efeito de estudo um andar completamente simulado foi introduzido para avaliação.
The advent of new multimedia forms has attracted many customers, concerns not only with the service, but also with the quality of service that can be offered. The WLAN have become the most common form of Internet routing, this is because of its low cost and ease implementation. To achieve a good routing planning it’s necessary to use propagation models. In the literature many propagation models make the prediction of signal strength but do not include the provision of quality of service metrics (parameters). In this sense this work proposes to develop an empirical propagation model indoor multi-floor that not only predicts the received power, but also makes a prediction for some metrics of QoS for VoIP (Voice over Internet Protocol). To develop the proposed model, measurement campaigns were performed on separate floors of a building while maintaining the position of the access point AP) fixed in one floor. Studies of analytical geometry were taken for counting and aggregation of losses on floors/walls. The results of the proposed model were compared with model of literature which has similar propagation behavior. To improve a comparison, a test with a simulated floor was introduced using the proposed model.

Recent years the research focus began on “Quality of Experience” (QoE) that addresses user satisfaction level and improvement of service. The notation sustainable throughput, sometimes also called reliable throughput, ensures user satisfaction level at the same time requires an optimum resource to provide the service. In the context of communication, it becomes important to analyze user behavior with respect to network performance.             Since the user is closer to the transport layer than the network layer, there opens a new domain to relate “QoE aware sustainable throughput” and “TCP throughput”. There is a need to further investigation of “QoE aware sustainable throughput” as it the one which sufficiently QoE, while “TCP throughput” is the result of a control process on a layer. Moreover, it is essential to estimate the QoE aware sustainable throughput based on HTTP streaming on the server and client application may result in a closer understanding of the nature of TCP in terms of user expectation.                In this study, we evaluated the performance of video streaming considering the TCP throughput in the presence of network disturbances, packet loss, and delay. The TCP packet behavior is observed in the experimental test setup. The quality assessment at which the QoE problems can still be kept at the desired level is determined. Mean opinion scores of the preferred use cases for the dash and non-dash server is used to estimate the relationship factor between “TCP throughput” and “QoE aware sustainable throughput”.

L'IEEE 802.11 (Wi-Fi) est le standard de WLAN (Wireless Local Area Network). En conséquence, le marché des produits dotés de la technologie réseau Wi-Fi est en plein essor et a provoqué une véritable révolution dans le monde de l'informatique. Cependant, la communication utilisant le Wi-Fi ne présente pas, pour autant, que des avantages. La grande différence entre le débit théorique et le débit effectif dépend de nombreux paramètres. Il est, par exemple, difficile de faire du streaming vidéo haute définition en utilisant un réseau IEEE 802.11g, alors que le débit théorique le permet parfaitement. La technologie WLAN souffre d'autres contraintes, comme la nature vulnérable du médium sans fil (interférences électromagnétiques, multi-trajet...), l'accès indéterministe au médium, la limitation de la bande passante...Les applications utilisant les réseaux Ad Hoc deviennent de plus en plus complexes et offrent de nouveaux services qui exigent des performances réseau de plus en plus élevées. De ce fait, la Qualié de Service (QdS) dans les réseaux Ad Hoc est un sujet de recherche ouvert. La bande passante est un indicateur très important pour la garantie de la QdS. Dans notre travail de thèse, nous avons étudié l'un des aspects de la QdS qui est la Bande Passante Disponible (BPD) dans les réseaux Ad Hoc basés sur la norme IEEE 802.11. Particulièrement, nous nous sommes intéressés aux différentes techniques d'estimation de la BPD et avons évalué les performances de ces techniques du point de vue temps de réponse et précision des estimations. Ces techniques peuvent être utilisées dans d'autres types de réseaux sans fil ou filaire. Nos contributions sont, essentiellement , le développement de deux nouvelles techniques d'estimation de la bande passante SLOT (SLOps-Topp) et TOPP-NET (TOPP-Non invasive Estimation Technique). Ces deux techniques sont le résultat d'améliorations successives des techniques d'estimation qui existent dans la littérature (TOPP : Trains of Packet Pairs, SLoPS : Self-Loading Periodic Streams et NIMBE : Non Invasive Manet Bandwith Estimation) en mettant l'accent sur la précision et le délai de sondage des techniques d'estimation. Notre troisième contribution est une nouvelle méthode de filtrage adaptatif des estimations nommée ZONE-FILTER ( Filtrage par Zone). Cette méthode combine les filtres EWMA et la mèthode statistique SPC (Statistical Process Control).

The thesis deals with possibilities of using wavelet transform in the field of surface electrocardiogram (ECG) signals denoising and ECG signals measuring. Several algorithms have been used to detect and estimate T-wave alternans (TWA), such as spectral method (SM), Poincaré Mapping (PM) or correlation method (CM). T-wave alternans, also called repolarization alternans, is a phenomenon appearing in the electrocardiogram as a consistent fluctuation in the repolarization morphology on every-other-beat basis. Electrical TWA has been recognized as a marker of electrical instability, and has been shown to be related with patients at increased risk for ventricular arrhytmias. Presence of TWA has been reported in a wide range of clinical and experimental situations including long QT syndrome, myocardial infarction, angina pectoris, acute ischemia, etc. Projected methods of detection TWA are realized in Matlab software, and they are experimentally verified on real ECG signals from the European ST-T Database.

碩士
中國文化大學
資訊安全產業研發碩士專班
100
Recent years, with the rapid development of Internet and the popularity of fiber-optic network, the users can easily obtain a lot of information and services from the Internet. In particular, the demand for multimedia services such as Video On Demand (VOD), Voice Over Internet Protocol (VoIP), YouTube, Internet TV, on-line games and so on, has increased substantially. Therefore, the demand for the network bandwidth is increasing dramatically. If the existing enterprise network infrastructure does not provide better quality of network service and bandwidth management, and optimize the efficiency of the transmission, which will increase the cost of corporate services and reduce the quality of service, then the loss of a large number of customers results in business loss. However, to meet the substantial increase in bandwidth requirements and diversity services, the corporate is barely willing to invest in developing Internet services, which is added into an existing network in order to save costs. By doing so, the original designed maximum capacity might be overused and lead to the corporate service interruptions. In severe case, this may face business crisis. This thesis focuses on using NS2, a network simulation tool, to simulate a particular corporate network environment and test the quality of multimedia data transmission. Based on the simulation results, the potential bottleneck of this network will be found and a QoS management mechanism will be proposed. Through this control mechanism, the higher priority packets will be guaranteed to get a better performance in data flow. Finally, this thesis proposes an effective improvement plan and shows the estimated quality of service over improved network, which will benefit the corporate to provide higher service level.

碩士
亞東技術學院
資訊與通訊工程研究所
94
Downlink orthogonality factor and downlink interference ratio are important parameters in downlink capacity estimating of WCDMA radio network. Both they are impacted on height, location and transmitting environment of WCDMA Base-stations. Four topics will be discussed in this thesis, the impulse response of multipath propagation environment, evaluation of WCDMA Downlink orthogonality factor, path loss modelling and estimation of the downlink QoS capacity. Lots of measurements have been made on live WCDMA base-stations by wireless communication network signal measuring platform. We calculate time dispersion statistics of measured data, and construct the impulse response of actuality multipath propagation environment in exponential power profile. The channel model was analyzed and compared with COST259 model as well. In literature, there are two metheds to calaculate WCDMA downlink Orthogonality factor. One is calculating orthogonality factor from the multiple path-loss factor without considering the effects of other issues in WCDMA communication system. The other is to derive exact equations from the downlink signal to interference ratio, but the correlation is long-term average over a data frame that the relationship between orthogonality factor and spreading factor can not be revealed in short term. Therefore, we propose new method to calculate downlink othogonality factor. The othogonality formula is derived from signal processing, but the compound signal processing cause the complex and lengthy calculation. So that we propose another method to evaluate downlink othogonality factor by correlation of connectative channelized and scrambled codes that used in actual WCDMA communication system. Multipath propagation channel is simulated by Monte Carlo method. A new algorithm is used, in calculating correlations of connectative channelized and scrambled codes signal, to evaluate the downlink othogonality factor. Averaging results from hundreds run time simulations are achieved by MMSE method. The adaptive path loss model was established by using the dual least-square approach on existing 3G radio network. Calculating the downlink interference ratio, , can be achieved by using cell planning and optimization plateform. There are four types of quality of services for different requirements, that including conversational calss, streaming class, interactive class and background class. The quality of service, , required time delay and data rates are different in services. Thereforce, the downlink QoS capacity will not be the same as well. The estimation of WCDMA downlink QoS capacity can be established according to the orthogonality empirical model and downlink interference evaluation. We compare the on-site measuring WCDMA downlink capacity in Panchiao area with the estimation by the empirical model. The results show excellent consistence in several test cases and sites.

碩士
國立成功大學
電腦與通信工程研究所
105
Conventional quality-of-service (QoS) routing algorithms in wireless ad hoc networks usually determine a feasible route based on the evaluation whether the remaining available network resources is sufficient to support the required quality of service of a new incoming data flow. However, the established QoS route will suffer from broken link due to the mobility of users or intermediate nodes in mobile ad hoc networks (MANETs).To deal with this problem, this thesis proposes a novel QoS routing protocol with route-survival-time estimation for the IEEE 802.11 DCF based MANETs. In this protocol, we adopt either Global Positioning System (GPS) or mathematical analytic scheme to calculate and predict the link duration between two neighboring nodes. As the result, we can select a QoS route with the longest survival time for the new flow to reduce the route-broken probability. Simulation results show that the proposed routing protocol outperforms the other known algorithm for MANETs.

碩士
國立成功大學
電腦與通信工程研究所
94
As the wireless communication technology improves dramatically and the wireless communication service becomes more and more popular during the past ten years, more and more users like to convey their message via the wireless environment. And ad hoc network is one of the most important communication systems for the future. However, the primitive routing protocols such as AODV and DSR don’t have any mechanism to avoid network congestion. When the network loading becomes heavy, the real time data packets are unable to convey success smoothly or it may be dropped because the delay of packet exceeds delay upper bound. As a result, in order to supply QoS for real time data, many papers discuss how to control system loading recently. 　There are two routing protocols that have been proposed previously and they both utilize admission control scheme to provide QoS for real time application with bandwidth estimation. However, the improvement of performance is limited because of using too much extra routing messages. Hence we propose a low overhead admission control mechanism which is called LO-QARP (Low Overhead QoS Admission Control Protocol) in this paper. According to simulation results, we find system traffic effectively controlled and routing overhead decreased, so it has not only increased the transmission efficiency, but also reduced the delay of packet.

碩士
元智大學
資訊工程學系
95
For the recent years, many routing protocols for mobile ad hoc networks had been proposed. However most of the researches focus on finding a shortest path, and doesn’t take into account the network loading. In Best Effort network environment, it would cause the network overload, increase the delay time of packet delivery and decrease the transmission throughput, thus slow down the overall performance. For real-time applications, providing a QoS Routing protocol, becomes an important issue. In this paper, a QoS routing protocol based on signal strength has been proposed. Through periodically probing network, the source node could constantly be switched to a better transmission path, and therefore the path broke time may be reduced. Besides, we propose effective solutions to solve bandwidth estimation and signal strength problems for probing. In addition to providing the bandwidth requirement, this paper also establishes a more stable and mobility path, and reduce the end to end packet delivery delay time.

碩士
國立成功大學
工程科學系
106
The real-time heartbeat detection in electrocardiogram (ECG) signal is still an important and challenging issue due to the advancement of medical equipment and healthcare. In contrast to conventional works, this work focuses on developing a new methodology based on the Bayesian framework. More specifically, we propose two new algorithms for the real-time heartbeat detection, i.e., variance-based QRS detector (VBD) and maximum-likelihood estimation (MLE). Firstly, we reduce the physiological interference in ECG signal through signal preprocessing using a band-pass filter. Then, continuously detect the onset, duration, and period of a QRS complex with the proposed VBD and MLE. The algorithms are evaluated and verified by two database, such as MIT-BIH arrhythmia and QT database. For the 48 records of MIT-BIH arrhythmia database, the obtained detection result shows a sensitivity, Se, of 99.85% and a positive predictivity, P+, of 99.85%. For the 105 records of QT database, the obtained detection result shows a sensitivity, Se , of 99.96% and a positive predictivity, P+, of 99.94%, is accurate as well.

碩士
國立臺灣海洋大學
環境生物與漁業科學學系
100
Oligotrich ciliates were sampled semimonthly from the coastal waters of northeastern Taiwan during March, 2011 and January, 2012. Each sample was divided equally into two subsamples, one was fixed by Formalin with Utermöhl method and the other was processed with the quantitative protargol stain (QPS) to study the abundance, biovolume and identification of oligotrich ciliates. The abundance of oligotrich ciliates observed under QPS were more than that under the fixation of Formalin. However, Formalin damaged ciliate specimens of about 28 µm in length in the family Strombidinopsidae. The culture experiment showed that the abundance of oligotrich ciliates after Formalin fixation was 29% of that of live specimens, and longer preservation time damaged more oligotrich ciliates. Furthermore, even though the abundance of oligotrich ciliates after QPS was 42% of that of live specimens, there was no further reduction of abundance within one week. The ESD (Equivalent Spherical Diameter) of oligotrich ciliates varied with species, fixations and preservation time. Formalin exerted small impact on the ESD of fixed cells, slightly decreasing cell size over the accumulation of preservation time. However, the ESD length of oligotrich ciliates preserved with QPS was 72% and 60-67% of that preserved with the fixation of Formalin and live species, respectively, and stabilized during a week. Although the proportion of specimens identified at generic level of oligotrich ciliates was the same (71%) with Formalin and QPS method, it is impossible to differentiate species with Formalin method. The QPS method provided with more information about the diversity of oligotrich ciliates, because 83% of the specimens identified to generic level could be further identified to species. As a result, the method of QPS is apparently a better method to study the ecosystem and biodiversity of oligotrich ciliates.

La téléopération en réseau est une thématique émergente, où un humain (le maître) communique avec un esclave commandé à distance à travers un réseau de communication, pour l'échange des données de commande et de mesure. Pour la téléopération longue distance, ces informations traversent divers réseaux hétérogènes ou hybrides interconnectés ensemble. Nous traitons également le cas où un segment sera sans fil, ce qui permet d'envisager que l'esclave soit mobile (véhicule télé-opéré par exemple). Une étude indépendante des aspects commande et des aspects réseau entraîne l'atteinte d'objectifs locaux, qui peuvent le cas échéant être ensuite fortement dégradés après l'intégration des deux aspects. L'utilisation de réseaux partagés, comme internet, en lieu et place d'une liaison dédiée (point à point, liaison virtuelle) est également un défi, en particulier dans le cas de la longue distance. Les mécanismes de qualité de service (QdS) d'un réseau, en particulier du réseau hétérogène, doivent pouvoir être traités par les autres réseaux ; ces points sont assez souvent traités avec un point de vue d'applications multimedia, plus rarement avec le point de vue de la téléopération critique. L'approche de téléopération en réseau peut profiter de ces mécanismes de qualité de service en utilisant des priorités ou des réservations de bandes passantes en fonction des critères de commande et de transparence. Cela peut entraîner une adaptation des ressources réseau en fonction des besoins des objectifs de téléopération afin de transporter l'information en satisfaisant les besoins bout en bout de l'application, cette notion devant être précisée. Lorsqu'on considère la QdS avec un point de vue réseau, elle consiste principalement à la gestion de flux de communication, en prenant en compte des paramètres de besoin et d'ordonnancement. Si l'on prend en compte le point de vue de la téléopération, la QdS entraîne des conséquences sur la qualité de commande (QdC) ce qui inclut la stabilité, la transparence et la téléprésence. De plus, l'interface humaine peut également avoir des besoins spécifiques en termes de téléprésence, ce qui peut entraîner des conséquences sur la répartition de la charge du réseau. Afin d'intégrer les deux approches de QdS et de QdC pour apporter une meilleure réponse au problème posé, nous proposons une approche de coconception avec d'une part une adaptation de la QdS aux besoins de la Qdc (qualité de la transparence) et d'autre part une adaptation de la Qdc (par exemple dégradation de la qualité du flux vidéo) à la disponibilité du réseau. Nous avons considéré deux cas de figures. Dans un premier temps, sans tenir compte des mécanismes de QdS du réseau (approche dite du meilleur effort ou best effort) et par l'adaptation au mieux de l'application, pour répondre aux besoins de la téléopération. La seconde approche considère un réseau orienté QdS entre le maître et l'esclave, où différentes priorités peuvent être attribuées aux flux nécessaires à la téléopération, en fonction des contextes. L'approche proposée est finalement mise en oeuvre sur NeCS-Car, la voiture téléopérée disponible au Laboratoire.

碩士
高雄醫學大學
醫學研究所碩士班
93
Introduction: In patients with hypertension, increases in arterial stiffness have been associated with a higher risk of coronary and cerebrovascular diseases. Arterial stiffness can be assessed noninvasively by measurement of pulse wave velocity (PWV). Practical problems in the measurement of PWV arise when the points of measurement (eg, carotid and femoral artery) are not in the same line of flow travel and the actual arterial distance between recording sites on the surface of the body was not exact. We developed a simple and novel index as QPV interval (msec) that was the time interval between the onset of QRS complex from a surface electrocardiogram and the point of peak flow velocity of left brachial artery (BA) determined by ultrasound. We proposed that this QPV interval can be served as an index marker of arterial stiffness. Methods: Sixty-six patients (mean age 49.3±10.5) with untreated essential hypertension were enrolled. Brachial-ankle PWV (baPWV) was determined by VP 1000 automated ABI/PWV analyzer and BA ultrasonography was prerformed simultanelusly to measure the QPV interval. The mean QPV interval was obtained by measuring the time interval at two consecutive pulsatile velocity waveform. Flow- and nitroglycerin-mediated vasodilation of BA were also determined. Results: The mean QPV interval was 196.1±18.9 msec (range 155-245 msec) and mean baPWV was 1785.7±293.3 cm/sec (range 1054-2514 cm/sec). The mean baPWV was significantly higher in patients with QPV interval≦195 msec than in patients with QPV interval＞195 msec (1955.7±255.1 vs. 1605.0±213.8 cm/sec, P < 0.001). Univariate linear regression demonstrated a significantly inverse correlation between QPV interval and baPWV (r =－0.671, P < 0.001). In a multivariate regression model that adjusted for age, sex, body mass index (BMI) and other potential baPWV determinants, the QPV interval was still inversely associated with baPWV (P < 0.001). No significant association could be demonstrated between baPWV and flow- or nitroglycerin-mediated vasodilation. Conclusions: In patients with untreated essential hypertension, QPV interval has significantly inverse correlation to baPWV, independent of BMI, age and other baPWV determinants. The QPV interval can be served as a simple and convenient parameter for assessing the severity of arterial stiffness.