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Nourani-Dargiri, Mehrdad. "Area and delay estimation for constraint-driven high-level synthesis." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1057603424.
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Kuroiwa, Yohei. "Sensitivity Shaping under Degree Constraint : Nevanlinna-Pick Interpolation for Multivarible and Time-Delay Systems." Licentiate thesis, KTH, Mathematics (Dept.), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4821.
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Loxton, Ryan Christopher. "Optimal control problems involving constrained, switched, and delay systems." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/1479.
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In this thesis, we develop numerical methods for solving five nonstandard optimal control problems. The main idea of each method is to reformulate the optimal control problem as, or approximate it by, a nonlinear programming problem. The decision variables in this nonlinear programming problem influence its cost function (and constraints, if it has any) implicitly through the dynamic system. Hence, deriving the gradient of the cost and the constraint functions is a difficult task. A major focus of this thesis is on developing methods for computing these gradients. These methods can then be used in conjunction with a gradient-based optimization technique to solve the optimal control problem efficiently.The first optimal control problem that we consider has nonlinear inequality constraints that depend on the state at two or more discrete time points. These time points are decision variables that, together with a control function, should be chosen in an optimal manner. To tackle this problem, we first approximate the control by a piecewise constant function whose values and switching times (the times at which it changes value) are decision variables. We then apply a novel time-scaling transformation that maps the switching times to fixed points in a new time horizon. This yields an approximate dynamic optimization problem with a finite number of decision variables. We develop a new algorithm, which involves integrating an auxiliary dynamic system forward in time, for computing the gradient of the cost and constraints in this approximate problem.The second optimal control problem that we consider has nonlinear continuous inequality constraints. These constraints restrict both the state and the control at every point in the time horizon. As with the first problem, we approximate the control by a piecewise constant function and then transform the time variable. This yields an approximate semi-infinite programming problem, which can be solved using a penalty function algorithm. A solution of this problem immediately furnishes a suboptimal control for the original optimal control problem. By repeatedly increasing the number of parameters used in the approximation, we can generate a sequence of suboptimal controls. Our main result shows that the cost of these suboptimal controls converges to the minimum cost.The third optimal control problem that we consider is an applied problem from electrical engineering. Its aim is to determine an optimal operating scheme for a switchedcapacitor DC-DC power converter—an electronic device that transforms one DC voltage into another by periodically switching between several circuit topologies. Specifically, the optimal control problem is to choose the times at which the topology switches occur so that the output voltage ripple is minimized and the load regulation is maximized. This problem is governed by a switched system with linear subsystems (each subsystem models one of the power converter’s topologies). Moreover, its cost function is non-smooth. By introducing an auxiliary dynamic system and transforming the time variable (so that the topology switching times become fixed), we derive an equivalent semi-infinite programming problem. This semi-infinite programming problem, like the one that approximates the continuously-constrained optimal control problem, can be solved using a penalty function algorithm.The fourth optimal control problem that we consider involves a general switched system, which includes the model of a switched-capacitor DC-DC power converter as a special case. This switched system evolves by switching between several subsystems of nonlinear ordinary differential equations. Furthermore, each subsystem switch is accompanied by an instantaneous change in the state. These instantaneous changes—so-called state jumps—are influenced by control variables that, together with the subsystem switching times, should be selected in an optimal manner. As with the previous optimal control problems, we tackle this problem by transforming the time variable to obtain an equivalent problem in which the switching times are fixed. However, the functions governing the state jumps in this new problem are discontinuous. To overcome this difficulty, we introduce an approximate problem whose state jumps are governed by smooth functions. This approximate problem can be solved using a nonlinear programming algorithm. We prove an important convergence result that links the approximate problem’s solution with the original problem’s solution.The final optimal control problem that we consider is a parameter identification problem. The aim of this problem is to use given experimental data to identify unknown state-delays in a nonlinear delay-differential system. More precisely, the optimal control problem involves choosing the state-delays to minimize a cost function measuring the discrepancy between predicted and observed system output. We show that the gradient of this cost function can be computed by solving an auxiliary delay-differential system. On the basis of this result, the optimal control problem can be formulated—and hence solved—as a standard nonlinear programming problem.
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Holmberg, Jonas. "OFFLINE SCHEDULING OF TASK SETS WITH COMPLEX END-TO-END DELAY CONSTRAINTS." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-35694.
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Software systems in the automotive domain are generally safety critical and subject to strict timing requirements. Systems of this character are often constructed utilizing periodically executed tasks, that have a hard deadline. In addition, these systems may have additional deadlines that can be specified on cause-effect chains, or simply task chains. They are defined by existing tasks in the system, hence the chains are not stand alone additions to the system. Each chain provide an end-to-end timing constraint targeting the propagation of data through the chain of tasks. These constraints specify the additional timing requirements that need to be fulfilled, when searching for a valid schedule. In this thesis, an offline non-preemptive scheduling method is presented, designed for single core systems. The scheduling problem is defined and formulated utilizing Constraint Programming. In addition, to ensure that end-to-end timing requirements are met, job-level dependencies are considered during the schedule generation. Utilizing this approach can guarantee that individual task periods along with end-to-end timing requirements are always met, if a schedule exists. The results show a good increase in schedulability ratio when utilizing job-level dependencies compared to the case where job-level dependencies are not specified. When the system utilization increases this improvement is even greater. Depending on the system size and complexity the improvement can vary, but in many cases it is more than double. The scheduling generation is also performed within a reasonable time frame. This would be a good benefit during the development process of a system, since it allows fast verification when changes are made to the system. Further, the thesis provide an overview of the entire process, starting from a system model and ending at a fully functional schedule executing on a hardware platform.
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Li, Ruogu. "Principles and Methods of Adaptive Network Algorithm Design under Various Quality-of-Service Requirements." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354642003.
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Horák, Michael. "Určení polohy stanic v síti Internet pomocí přenosového zpoždění." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220305.
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This thesis covers the topic of determination of geographical location of a host in internet network while utilizing measurement of the end to end delay and implementation of Constraint-Based Geolocation. Gradually I go through issue of the delay in computer networks and ways how to measure it. Next chapter describes a few ways to geolocate host in internet network with emphasis on the CBG method. Another chapter is dedicated to describing a way to project spherical coordinates to the two dimensional space, which has been used in implementation of geolocation method. Chapter about implementation builds upon the facts given in previous chapters while functions of the program written in the JAVA programing language are being explained. Two similar geolocation methods were implemented. By comparing the results gained by implementation, new method of geolocation is proposed and devised. It combines properities of both previous methods. There are results of the implemented methods and their comparation to the one of the source documents used in creation of this thesis in summary section.
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Nikbakht, Homa. "Networks with mixed-delay constraints." Electronic Thesis or Diss., Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAT046.
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Les réseaux de communication sans fil modernes doivent s'adapter à différents types de trafic de données avec des contraintes de latence différentes. Les applications vidéo sensibles à la latence, en particulier, représentent une part croissante du trafic de données. En outre, les réseaux modernes doivent accepter des débits de données élevés, ce qu'ils peuvent faire par exemple avec des terminaux coopératifs ou avec l'assistance de relais tels que les drones. Cependant, la coopération introduit généralement des retards de communication supplémentaires et n'est donc pas applicable au trafic de données sensibles à la latence.Cette thèse porte sur les réseaux d'interférence avec des contraintes de latence mixtes et sur les architectures de systèmes où des émetteurs et/ou des récepteurs voisins peuvent coopérer. Dans de tels systèmes, les messages sensibles à la latence doivent être encodés et décodés sans délai et ainsi ne peuvent pas bénéficier des liens de coopération disponibles. Nous proposons différents schémas de codage pour permettre la transmission simultanée de messages sensibles et insensibles à la latence. Pour les schémas proposés, nous analysons les gains de multiplexage (MG) qu'ils réalisent sur le réseau de transfert intercellulaire souple de Wyner, le réseau symétrique de Wyner, le réseau hexagonal et le réseau hexagonal sectorisé. Pour le réseau de transfert souple de Wyner et le réseau symétrique de Wyner, nous identifions aussi des résultats étroits s'agissant de leurs limites en théorie de l'information et nous définissons ainsi l'ensemble exact de paires MG qui peuvent être obtenus simultanément pour les données sensibles et insensibles à la latence. Ces résultats montrent que lorsque les émetteurs et les récepteurs peuvent coopérer et que les taux de coopération sont suffisamment élevés, il est possible d'obtenir le plus grand MG possible pour les messages sensibles à la latence sans pénaliser la somme maximale des MG pour l'ensemble des messages sensibles et insensibles à la latence. Cependant, la somme des MG des systèmes que nous proposons pour le modèle hexagonal est diminuée en présence de données sensibles à la latence. Cette pénalité disparaît dans le cas du réseau hexagonal sectorisé quand chaque cellule est divisée en trois secteurs non interférents en équipant les stations de base d'antennes directionnelles.Nous proposons, de surcroît, des schémas de codage similaires en fonction de différents types d'activité aléatoire de la part des usagers du réseau. Nous considérons plus particulièrement deux configurations. Dans la première configuration, l'augmentation du taux de MG correspondant aux données sensibles à la latence diminue toujours la somme des MG. En revanche, dans la seconde configuration, pour certains paramètres, la plus grande somme des MG est obtenue au maximum du taux de MG correspondant aux données sensibles à la latence et donc l'augmentation des MG sensibles à la latence améliore la somme des MG.Nous étudions aussi un réseau d'accès radio "cloud" avec des contraintes de latence mixtes, c'est-à-dire où chaque utilisateur mobile peut simultanément envoyer un flux sensible à la latence et un flux qui la tolère et où seules les données sensibles sont décodées conjointement au sein du cloud. Pour ce réseau, nous dérivons les limites intérieures et extérieures de la région de capacité sous des contraintes de latence mixtes, et nous caractérisons précisément la région MG optimale. Lorsque le rapport signal/bruit (SNR) est élevé, nos résultats démontrent que, pour des capacités frontales modérées, le MG maximal pour les messages sensibles à la latence reste inchangé sur une large gamme de petits et moyens MG de messages sensibles à la latence. Pour un SNR modéré, les résultats montrent que lorsque le débit de messages sensibles à la latence est faible ou modéré, nous obtenons une somme de débit de données constante<br>Modern wireless communication networks have to accommodate different types of data traffic with different latency constraints. In particular, delay-sensitive video-applications represent an increasing portion of data traffic. Modern networks also have to accommodate high total data rates, which they can accomplish for example with cooperating terminals or with helper relays such as drones. However, cooperation typically introduces additional communication delays, and is thus not applicable to delay-sensitive data traffic.This thesis focuses on interference networks with mixed-delay constraints and on system architectures where neighbouring transmitters and/or neighbouring receivers can cooperate. In such systems, delay-sensitive messages have to be encoded and decoded without further delay and thus cannot benefit from available cooperation links.We propose various coding schemes that can simultaneously accommodate the transmission of both delay-sensitive and delay-tolerant messages. For the proposed schemes we analyze the multiplexing gains (MG) they achieve over Wyner's soft hand-off network, Wyner's symmetric network, the hexagonal network and the sectorized hexagonal network. For Wyner's soft hand-off network and Wyner's symmetric network, we also provide tight information-theoretic converse results and thus establish the exact set of MG pairs that can simultaneously be achieved for delay-sensitive and delay-tolerant data. These results demonstrate that when both transmitters and receivers cooperate and the cooperation rates are sufficiently large, it is possible to achieve the largest MG for delay-sensitive messages without penalizing the maximum sum MG of both delay-sensitive and delay-tolerant messages. In contrast, under our proposed schemes, the sending of delay-sensitive data in hexagonal models decreases the maximum sum MG. This penalty vanishes when we consider the sectorized hexagonal network where each cell is divided into three non-interfering sectors by employing directional antennas at the base stations.We further propose similar coding schemes for scenarios with different types of random user activity. We specifically consider two setups. In the first setup, each active transmitter always has delay-tolerant data to send and delay-sensitive data arrival is random. In the second setup, both delay-tolerant and delay-sensitive data arrivals are random. The obtained MG regions show that in the first setup, increasing the delay-sensitive MG always decreases the sum MG. In contrast, in the second setup, for certain parameters, the highest sum MG is achieved at maximum delay-sensitive MG and thus increasing the delay-sensitive MG provides a gain in sum MG.Additionally, we also study a cloud radio access network with mixed delay constraints, i.e., where each mobile user can simultaneously send a delay-sensitive and a delay-tolerant stream and only the delay-tolerant data is jointly decoded at the cloud unit. For this network, we derive inner and outer bounds on the capacity region under mixed delay constraints, and we exactly characterize the optimal MG region. At high signal-to-noise ratio (SNR), our results show that for moderate fronthaul capacities, the maximum MG for delay-sensitive messages remains unchanged over a large regime of small and moderate MGs of delay-sensitive messages. The sum MG is thus improved if some of the messages can directly be decoded at the base stations. At moderate SNR, the results show that when the data rate of delay-sensitive messages is small or moderate, the achievable sum rate is constant
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Lombardi, Warody. "Constrained control for time-delay systems." Phd thesis, Supélec, 2011. http://tel.archives-ouvertes.fr/tel-00631507.
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The main interest of the present thesis is the constrained control of time-delay system, more specifically taking into consideration the discretization problem (due to, for example, a communication network) and the presence of constraints in the system's trajectories and control inputs. The effects of data-sampling and modeling problem are studied in detail, where an uncertainty is added into the system due to additional effect of the discretization and delay. The delay variation with respect to the sampling instants is characterized by a polytopic supra-approximation of the discretization/delay induced uncertainty. Some stabilizing techniques, based on Lyapunov's theory, are then derived for the unconstrained case. Lyapunov-Krasovskii candidates were also used to obtain LMI conditions for a state feedback, in the ''original" state-space of the system. For the constrained control purposes, the set invariance theory is used intensively, in order to obtain a region where the system is ''well-behaviored", despite the presence of constraints and (time-varying) delay. Due to the high complexity of the maximal delayed state admissible set obtained in the augmented state-space approach, in the present manuscript we proposed the concept of set invariance in the ''original" state-space of the system, called D-invariance. Finally, in the las part of the thesis, the MPC scheme is presented, in order to take into account the constraints and the optimality of the control solution.
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Ward, Tyler. "Delay tolerance for constrained IPv6 networks." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/411270/.
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Low power sensor networks have traditionally been regarded as not having the capabilities required to connect them to the internet. New research into the Internet of Things has challenged this concept and is opening up new possibilities for sensor network capabilities. Environmental sensor networks are just one of the areas which will greatly benefit from this connectivity improvement. However, there are many challenges to be solved in order to make full and ecient use of these advancements. One of the major challenges which has been identied is the lack of connectivity when sensors are in low power sleep states. Previous solutions for low power devices have relied on application layer gateways to proxy communications to the sensors, but this restricts the exibility of the network as it is limited to the capabilities of the proxy. Delay Tolerant Networking (DTN) oers a solution to this problem by allowing sensors to respond and handle communications at their convenience. This thesis presents and evaluates a novel method and implementation of Delay Tolerant Networking using IPv6 extension headers. The proposed DTN extension header is found to have a signicantly lower packet size overhead than other DTN protocols. In addition, the protocol and systems to support it are entirely backwards and forwards compatible with the existing internet infrastructure allowing for it to be incorporated into existing deployments. The developed protocol forms a new state of the art for DTN on constrained sensor networks using end to end IP connectivity. Using this, a new range of low power IoT devices can be developed, featuring long battery lives and reliable connectivity.
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Chen, J. "Resource allocation for delay constrained wireless communications." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/19637/.
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The ultimate goal of future generation wireless communications is to provide ubiquitous seamless connections between mobile terminals such as mobile phones and computers so that users can enjoy high-quality services at anytime anywhere without wires. The feature to provide a wide range of delay constrained applications with diverse quality of service (QoS) requirements, such as delay and data rate requirements, will require QoS-driven wireless resource allocation mechanisms to efficiently allocate wireless resources, such as transmission power, time slots and spectrum, for accommodating heterogeneous mobile data. In addition, multiple-input-multiple-output (MIMO) antenna technique, which uses multiple antennas at the transmitter and receiver, can improve the transmission data rate significantly and is of particular interests for future high speed wireless communications. In the thesis, we develop smart energy efficient scheduling algorithms for delay constrained communications for single user and multi-user single-input-single-output (SISO) and MIMO transmission systems. Specifically, the algorithms are designed to minimize the total transmission power while satisfying individual user’s QoS constraints, such as rate, delay and rate or delay violation. Statistical channel information (SCI) and instantaneous channel state information (CSI) at the transmitter side are considered respectively, and the proposed design can be applied for either uplink or downlink. We propose to jointly deal with scheduling of the users that access to the channel for each frame time (or available spectrum) and how much power is allocated when accessing to the channel. In addition, the algorithms are applied with modifications for uplink scheduling in IEEE 802.16 Worldwide Interoperability for Microwave Access (WiMAX). The success of the proposed research will significantly improve the ways to design wireless resource allocation for delay constrained communications.
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Collins, Bruce E. "Transmission policies for time-varying channels with delay constraints /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3141834.
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Bocquillon, Ronan. "Data distribution optimization in a system of collaborative systems." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2232/document.
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Un système de systèmes est un système dont les composants sont eux-mêmes des systèmes indépendants, tous communiquant pour atteindre un objectif commun. Lorsque ces systèmes sont mobiles, il peut être difficile d'établir des connexions de bout-en-bout. L'architecture mise en place dans de telles situations est appelée réseau tolérant aux délais. Les données sont transmises d'un système à l'autre – selon les opportunités de communication, appelées contacts, qui apparaissent lorsque deux systèmes sont proches – et disséminées dans l'ensemble du réseau avec l'espoir que chaque message atteigne sa destination. Si une donnée est trop volumineuse, elle est découpée. Chaque fragment est alors transmis séparément.Nous supposons ici que la séquence des contacts est connue. On s'intéresse donc à des applications où la mobilité des systèmes est prédictible (les réseaux de satellites par exemple). Nous cherchons à exploiter cette connaissance pour acheminer efficacement des informations depuis leurs sources jusqu'à leurs destinataires. Nous devons répondre à la question : « Quels éléments de données doivent être transférés lors de chaque contact pour minimiser le temps de dissémination » ?Nous formalisons tout d'abord ce problème, appelé problème de dissémination, et montrons qu'il est NP-difficile au sens fort. Nous proposons ensuite des algorithmes pour le résoudre. Ces derniers reposent sur des règles de dominance, des procédures de prétraitement, la programmation linéaire en nombres entiers, et la programmation par contraintes. Une partie est dédiée à la recherche de solutions robustes. Enfin, nous rapportons des résultats numériques montrant l'efficacité de nos algorithmes<br>Systems of systems are supersystems comprising elements which are themselves independent operational systems, all interacting to achieve a common goal. When the subsystems are mobile, these may suffer from a lack of continuous end-to-end connectivity. To address the technical issues in such networks, the common approach is termed delay-tolerant networking. Routing relies on a store-forward mechanism. Data are sent from one system to another – depending on the communication opportunities, termed contacts, that arise when two systems are close – and stored throughout the network in hope that all messages will reach their destination. If data are too large, these must be split. Each fragment is then transmitted separately.In this work, we assume that the sequence of contacts is known. Thus, we focus on applications where it is possible to make realistic predictions about system mobility (e.g. satellite networks). We study the problem of making the best use of knowledge about possibilities for communication when data need to be routed from a set of systems to another within a given time horizon. The fundamental question is: "Which elements of the information should be transferred during each contact so that the dissemination length is minimized"?We first formalize the so-called dissemination problem, and prove this is strongly NP-Hard. We then propose algorithms to solve it. These relies on different dominance rules, preprocessing procedures, integer-linear programming, and constraint programming. A chapter is dedicated to the search for robust solutions. Finally experimental results are reported to show the efficiency of our algorithms in practice
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Al-Regib, Ghassan. "Delay-constrained 3-D graphics streaming over lossy networks." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/15428.
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Adams, David C. (David Christopher). "A delay-constrained cross-layer model using network coding." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91099.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.<br>27<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 79-81).<br>Traditionally, most packet-switched networks have only one wireless hop: the link between the end users and their access point. However, there is increasing interest in using wireless links to reach the edge of the network. Having more than one wireless link is a game changer. Network layer architecture is predicated on the assumption that the lower layers are reliable, but this comes at a high cost in terms of data rate on a band-limited, lossy wireless channel. This cost is tolerable over one underutilized link, but when the network demands high-capacity wireless links, it may be time to rethink the way the packet-switched network interacts with its underlying infrastructure. The aim of this thesis is to provide a general model that can be used to frame a wide variety of cross-layer coding problems. We do not explicitly consider the channel code, medium access, or modulation; instead, we leverage the maturity of these fields to observe the general effect they produce on higher layers. We focus our model on applications where delay is constrained, which forces us to consider coding results in the regime where code length is non-asymptotically large. In trying to extend our analysis to multi-hop flows, we develop an analytical tool that can be useful in wider applications. This tool simplifies certain network flows to a distribution on the amount of information available to the destination; it is a step towards characterizing network information flows in the non-asymptotic regime. Finally, we will use the model to design encoding schemes, given practically-motivated constraints.<br>by David C. Adams.<br>S.M.
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Li, Xiaochen. "Power control and resource allocation for delay-constrained communications." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024302.
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Lakay, Elthea Trevolee. "SIP-based content development for wireless mobile devices with delay constraints." Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_9048_1182233050.
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<p>SIP is receiving much attention these days and it seems to be the most promising candidate as a signaling protocol for the current and future IP telephony services. Realizing this, there is the obvious need to provide a certain level of quality comparable to the traditional telephone service signalling system. Thus, we identified the major costs of SIP, which were found to be delay and security. This thesis discusses the costs of SIP, the solutions for the major costs, and the development of a low cost SIP application. The literature review of the components used to develop such a service is discussed, the networks in which the SIP is used are outlined, and some SIP applications and services previously designed are discussed. A simulation environment is then designed and implemented for the instant messaging service for wireless devices. This environment simulates the average delay in LAN and WLAN in different scenarios, to analyze in which scenario the system has the lowest costs and delay constraints.</p>
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Kinnally, Michael Sean. "Stationary distributions for stochastic delay differential equations with non-negativity constraints." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3355747.
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Thesis (Ph. D.)--University of California, San Diego, 2009.<br>Title from first page of PDF file (viewed June 23, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 114-116).
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Irava, Venkata Srinivas. "Low-cost delay-constrained multicast routing heuristics and their evaluation." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Summer2006/v%5Firava%5F072106.pdf.
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Gorius, Manuel [Verfasser], and Thorsten [Akademischer Betreuer] Herfet. "Adaptive delay-constrained internet media transport / Manuel Gorius. Betreuer: Thorsten Herfet." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2013. http://d-nb.info/1052779743/34.
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Xu, Chendong. "Delay-constrained power-efficient data aggregation framework in sensor-actor networks." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28260.
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In data aggregation problems, sensor measurements from the whole sensory field are collected at the data sink periodically or on-demand as a single report using functions such as average, maximum, minimum, counts, deviation, etc. This thesis is to design a data aggregation framework applicable for real-time sensor-actor networks. Our goal is to set up a reporting tree that will minimize power consumption at individual nodes while preserving delay requirements.
Existing solutions to data aggregation problem usually use hop count as the energy cost metric and/or operate in a centralized fashion. The only known delay bounded power efficient localized algorithm [MGPA] sets up an initial power efficient tree (regardless of delay), and then dynamically changes the tree based on measured delay in ongoing traffic, with speed-ups and slow-downs achieved by using maximal/minimal transmission ranges at some nodes. We show here that the initial tree is closer to hop count than power optimal while the energy consumption per node is apparently unbalanced.
We propose to construct a power optimal delay bounded data aggregation tree, assuming delay is proportional to hop count, which is a reasonable approximation in low traffic scenarios. Our desired hop progress (DHP) scheme constructs a data aggregation tree rooted at a sink/actor using only edges of localized minimal spanning tree (LMST) over all sensors, if delay along this tree is acceptable and power consumption is to be near optimal, like in [TKS]. Otherwise, hop selection (along LMST) made at each step is subject to the ratio of potential delay to message lifetime. The main idea is to reduce the network's overall energy consumption and balance energy consumptions at nodes by applying approximately equal hop lengths along the tree. There are two variants of DHP: DHP with Area coverage algorithm (DHPA), and DHP with Area coverage algorithm and CDS construction algorithm (DHPAC). In DHPA algorithm, area coverage algorithm is applied first to select a subset of active sensors that monitors the same area as the original set, thus allowing the rest of sensors to sleep. Then DHP is applied on the set of active sensors. In DHPAC protocol, a connected dominating set (CDS) is constructed over active sensors. Active sensors not in CDS report to their nearest CDS neighbors (related delay counted at the parent node), and DHP is then applied over LMST of CDS nodes and links in CDS. Experimental results indicate that DHP can totally save up to 75% energy and extend up to 123% network lifetime in comparison with [MPGA]. Meanwhile, DHPA and DHPAC also present significantly better energy efficiency than the variant of [MPGA], where area coverage algorithm is also implemented.
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Shehab, M. (Mohammad). "Performance of delay constrained multi-user networks under block fading channels." Master's thesis, University of Oulu, 2017. http://jultika.oulu.fi/Record/nbnfioulu-201704291630.
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Abstract. Effective Capacity (EC) indicates the maximum communication rate subject to a certain delay constraint while the effective energy efficiency (EEE) is the ratio between this EC and power consumption. In this thesis, we analyze the EC and EEE of multi-user networks operating in the finite blocklength (FB) regime. We consider a layout in which a number of users communicate through a common controller. A closed form approximation for the per-user EC is obtained in Nakagami-$m$ fading collision channels. The interference between transmitted data packets degrades the EC of each user. We analyze this decrease proposing three methods to alleviate the interference effect for one of the users namely power control, delay relaxation and joint compensation. Our results show that systems with stringent delay constraints favor power controlled compensation while for shorter packets, the amount of compensation needed by both $\theta$ relaxation and power increases is higher. Thus, it is more costly to compensate networks transmitting shorter packets. For the hybrid method, we maximize an objective function whose parameters are determined according to the design priorities (e.g. rate and latency requirements). Results reveal that there is a unique throughput maximizer which is obtained at an intermediate operational point applying both power control and delay relaxation in the joint compensation process. Furthermore, we characterize the per-user EEE for different power consumption models. The results show that accounting for empty buffer probability enhances the per-user EEE. Considering flexible transmission power and extending the maximum delay tolerance boosts the per-use EEE which is depicted in the thesis as well.Suorituskyvyn analysointi viiverajoitetussa usean käyttäjän verkossa lohkohäipyvissä kanavissa. Tiivistelmä. Efektiivinen kapasiteetti kertoo suurimman tietoliikenteen datanopeuden määritetyillä viiverajoituksilla, kun taas efektiivinen energiatehokkuus on efektiivisen kapasiteetin ja tehonkulutuksen suhde. Tässä diplomityössä analysoidaan efektiivistä kapasiteettia ja efektiivistä energiatehokkuutta monisolmuverkoissa, kun käytetään äärellistä lohkon pituutta. Työssä käytetään mallia, jossa tietty määrä käyttäjiä kommunikoi yhteisen kontrolliyksikön ohjaamana. Käyttäjäkohtaisen efektiivisen kapasiteetin approksimaatio datapakettien törmäyksiä mallintavassa Nakagami-m -häipyvässä kanavassa esitetään suljetussa muodossa. Lähetettyjen pakettien välinen häiriö pienentää kunkin käyttäjän efektiivistä kapasiteettia. Tätä ilmiötä pyritään lieventämään kolmella ehdotetulla menetelmällä eli tehonsäädöllä, viiveen relaksoinnilla ja näiden yhdistelmällä. Tutkimustulokset osoittavat, että tiukkojen viiverajoitusten voimassa ollessa tehopohjainen kompensointi toimii parhaiten kun taas lyhyille paketeille vaaditaan molempia menetelmiä. Niinpä lyhyitä paketteja lähettävien verkkojen kompensointimenetelmät ovat kalliita. Hybridimenetelmässä maksimoidaan kohdefunktio, jonka parametrit määritellään suunnittelukriteerien mukaan (esim. datanopeus- ja viivevaatimukset). Tulokset paljastavat, että löytyy yksittäinen verkon läpäisykyvyn maksimoiva keskialueen toimintapisteen kohta teho- ja viivepohjaista kompensointia yhdessä käytettäessä. Lisäksi työssä mallinnetaan solmukohtaista efektiivistä energiatehokkuutta eri tehonkulutusmalleilla. Tulokset osoittavat, että ei-tyhjän puskurin todennäköisyyden huomioon ottaminen parantaa käyttäjäkohtaista efektiivistä energiatehokkuutta. Työssä kuvataan myös, että joustavan lähetystehon käyttö yhdessä väljennetyn maksimiviivetoleranssin kanssa parantaa efektiivistä energiatehokkuutta.
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Deshpande, Milind Umesh. "Optimal video sensing strategy and performance analysis for wireless video sensors under delay constraints." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/5836.
Full textAbstract:
Thesis (M.S.)--University of Missouri-Columbia, 2005.<br>The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 17, 2006) Includes bibliographical references.
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WANG, XIAODONG. "QoS ISSUES AND QoS CONSTRAINED DESIGN OF WIRELESS SENSOR NETWORKS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1144634884.
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Bonalli, Riccardo. "Optimal control of aerospace systems with control-state constraints and delays." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS388.
Full textAbstract:
Dans ce travail, on s'est concentré sur le guidage optimal en temps réel de véhicules lanceurs, avec comme objectif, de développer un algorithme autonome pour la prédiction de stratégies de contrôle optimal, basé sur les méthodes indirectes, et capable de s'adapter à tout changement imprévu de scenario. Pour cela, tout d'abord nous fournissons une analyse géométrique précise dans le cas de contraintes mixtes, pour obtenir un cadre bien posé, et donc, appliquer correctement les méthodes indirectes. L'intégration numérique du problème est proposée par une combinaison efficace des méthodes indirectes avec des procédures d'homotopie, en améliorant, ainsi, à la fois robustesse et vitesse de calcul. De plus, nous améliorons le modèle dynamique en considérant des retards. Plus précisément, nous introduisons un cadre rigoureux d'homotopie pour résoudre des problèmes de contrôle optimal avec retards, à l'aide des méthodes indirectes. Nos contributions ont rendu possible le développement d'un logiciel automatique, indépendant et auto-régulé, propriété de l'ONERA, pour des applications réalistes dans le cadre de véhicules lanceurs, focalisé, en particulier, sur des scenarii d'interception optimale<br>In this work, we address the real-time optimal guidance of launch vehicles with the objective of designing an autonomous algorithm for the prediction of optimal control strategies, based on indirect methods, able to adapt itself to unpredicted changes of the original scenario. To this aim, we first provide an accurate geometric analysis in the presence of mixed control-state constraints to recover a well-posed framework and correctly apply indirect methods. A practical numerical integration of the problem is proposed by efficiently combining indirect methods with homotopy procedures, increasing robustness and computational speed. Moreover, we improve dynamical models by considering delays. More specifically, we introduce a rigorous and well-posed homotopy framework to recover solutions for optimal control problems with delays via indirect methods. All our contributions made possible the development of a fully automatic, independent and self-regulating software, today property of ONERA-The French Aerospace Lab, for general realistic endo-atmospheric launch vehicle applications focused on optimal missile interception scenarios
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Hotescu, Oana Andreea. "Vers la convergence de réseaux dans l'avionique." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0044.
Full textAbstract:
AFDX est le standard Ethernet commuté utilisé pour la transmission des flux avioniques. Pour des raisons de certification, le réseau AFDX déployé à présent dans les avions civils est très peu chargé. Cette thèse vise à étudier la possibilité envisagée par les avionneurs d’utiliser la bande passante AFDX restante pour transporter des flux non-avioniques additionnels (vidéo, audio, service). Ces flux ne doivent pas affecter les délais de transmission des flux avioniques. Pour multiplexer des flux avioniques et non-avioniques des politiques d’ordonnancement sont nécessaires au niveau des systèmes d’extrémité (end systems) et des commutateurs. Dans cette thèse, nous considérons l’exemple de la transmission sur AFDX de flux vidéo provenant des caméras de surveillance de l’avion. Le multiplexage des flux avioniques et vidéo est réalisé par l’introduction d’une table d’ordonnancement au niveau des end systems émetteurs et d’une politique de type SPQ dans les ports de sortie du commutateur. Cette solution préserve les contraintes temps-réel des flux avioniques, mais peut introduire des variations sur les délais de bout-en-bout des flux vidéo. Une allocation appropriée des flux avioniques dans la table d’ordonnancement peut réduire le retard d’émission des flux vidéo et ainsi, limiter les variations de délai. Nous proposons deux stratégies d’allocation des flux avioniques dans la table d’ordonnancement : une heuristique simple et une allocation optimale. L’allocation optimale est dérivée en résolvant un problème d’optimisation par contraintes qui minimise le retard d’émission des flux vidéo. Dans le cas des end systems moins chargés, l’allocation par heuristique est proche de l’optimale<br>AFDX is the standard switched Ethernet solution for transmitting avionic flows. Today’s AFDX deployments in commercial aircrafts are lightly loaded to ensure the determinism of control and command operations. This thesis aims at investigating a practical alternative envisioned by manufacturers that takes advantage of the remaining AFDX bandwidth to transfer additional nonavionic flows (video, audio, service). These flows must not compromise the in-time arrival of avionic ones. Thus, appropriate scheduling policies formultiplexing avionic flows with non-avionic flows are required at the emitting end systems and switch egress ports. We mainly focus on the transmission of additional flows carrying video streams from cameras located on the airplane to cockpit display. Multiplexing avionic flows with video flows is tackled by introducing table scheduling at the emitting end systems and a 2-priority levels SPQ service policy at switch egress ports. This solution preserves the real-time constraints of avionic flows but may introduce variations of the end-to-end delay of video ones. An appropriate allocation of slots to avionic flows in table scheduling can reduce the emission lag of video flows and thus, limit their delay variations. We propose two strategies to allocate avionic flows in the table scheduling: a simple one based on heuristics and an optimal one. Optimal schedules are derived by solving a constraint programming model minimizing the emission lag of video flows. For light traffic end systems, heuristic allocation is close to optimal
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Long, Yimiao. "Runnable to Task Mapping and Sequencing to Meet Data Propagation Delay Constraints in Automotive Real-Time Systems." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-288176.
Full textAbstract:
With the increasing complexity in the automotive embedded system, there are more stringent timing requirements that need to be satisfied. Autosar (AUTomotive Open System Architecture) was built to provide a standardized software architecture for electronic control units. In Autosar, runnables are pieces of code with dedicated functionality and executed by the operating system in the context of a task. To meet data age constraints through a chain of runnables, job-level dependencies that specify an ordering of runnable jobs, are proposed to guarantee that end-to-end timing constraints are met as long as the job order is met. The objective of this thesis is to propose a method to meet job-level dependencies as much as possible by mapping runnables to tasks and deciding the sequence of runnables within the task. The approach maps runnables that have dependencies into one task and sequence them in the specified order. Then, the approach groups tasks which have the same period to reduce the number of tasks. Besides, a feasibility test is necessary in the mapping step to ensure the system remains schedulable. Several experiments are performed to compare the proposed approach against related work. The percentage of dependencies met is the most important standard to judge which method has better performance. Besides, the runtime is also a factor to consider. From the experimental results, the proposed method which integrates job- level dependencies into runnable to task mapping and sequencing could reduce the number of dependencies that need to be considered during scheduling in order to meet the end-to-end delay constraints.<br>Med ökad komplexitet hos inbyggda system i fordon medföljer strängare timingkrav som måste uppfyllas. Autosar (AUTomotive Open System Architecture) byggdes för att tillhandahålla en standardiserad programvaruarkitektur för elektroniska styrenheter. I Autosar är runnables bitar kod med dedikerad funktionalitet och exikveras av operativsystemet i samband med en task. För att möta åldersbegränsningar genom en datakedja av runnables föreslås beroenden på jobbnivå som specificerar en ordning av runnables jobb för att garantera att tidsbegränsningar från slut till slut uppfylls så länge jobbordern uppfylls. Syftet med denna avhandling är att föreslå en metod för att möta beroenden på arbetsnivå så bra som möjligt genom att kartlägga runnables till uppgifter och bestämma sekvensen för runnables inom uppgiften. Tillvägagångssättet kartlägger runnables som har gemensamma beroenden in i en uppgift och ordnar dem i den angivna ordningen. Sedan grupperas uppgifter som har samma period för att minska det totala antalet. Dessutom är ett genomförbarhetstest nödvändigt i kartläggningssteget för att säkerställa att systemet förblir schemaläggbart. Flera experiment utförs för att jämföra det föreslagna tillvägagångssättet med relaterat arbete. Andelen beroenden som uppfylls är den viktigaste faktorn för att bedöma vilken metod som har den bättre prestandan. Dessutom är körtiden också en faktor att ta i hänsyn. Från de experimentella resultaten kan den föreslagna metoden som integrerar beroenden på jobbnivå in i en runnable för att kartlägga task. och sekvensering minska antalet beroenden som behöver tas i åtanke under schemaläggningen för att task de fördröjnings restriktioner från slut till slut.
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Grosic, Hasan, and Emir Hasanovic. "Optimizing Inter-core Data-propagation Delays in Multi-core Embedded Systems." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-44770.
Full textAbstract:
The demand for computing power and performance in real-time embedded systems is continuously increasing since new customer requirements and more advanced features are appearing every day. To support these functionalities and handle them in a more efficient way, multi-core computing platforms are introduced. These platforms allow for parallel execution of tasks on multiple cores, which in addition to its benefits to the system's performance introduces a major problem regarding the timing predictability of the system. That problem is reflected in unpredictable inter-core interferences, which occur due to shared resources among the cores, such as the system bus. This thesis investigates the application of different optimization techniques for the offline scheduling of tasks on the individual cores, together with a global scheduling policy for the access to the shared bus. The main effort of this thesis focuses on optimizing the inter-core data propagation delays which can provide a new way of creating optimized schedules. For that purpose, Constraint Programming optimization techniques are employed and a Phased Execution Model of the tasks is assumed. Also, in order to enforce end-to-end timing constraints that are imposed on the system, job-level dependencies are generated prior and subsequently applied during the scheduling procedure. Finally, an experiment with a large number of test cases is conducted to evaluate the performance of the implemented scheduling approach. The obtained results show that the method is applicable for a wide spectrum of abstract systems with variable requirements, but also open for further improvement in several aspects.
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Sanlaville, Éric. "Conception et analyse d'algorithmes de liste en ordonnancement preemptif." Paris 6, 1992. http://www.theses.fr/1992PA066325.
Full textAbstract:
Cette these traite de l'ordonnancement de taches sur des machines paralleles. Nous considerons un ensemble de taches de durees quelconques, liees par des contraintes de precedente. Elles doivent s'executer sur des machines identiques, qui ne sont pas toutes disponibles a chaque instant (ordonnancement sur profil variable); elles peuvent etre interrompues (preemptee) puis reprises sur n'importe quelle machine, a tout moment. Le critere d'optimisation est la minimisation, soit de la date de fin de la derniere tache, soit du plus grand retard quand des dates d'echeance sont associees aux taches. On trouve ce genre de problemes en informatique parallele comme en gestion d'atelier de production: les notions de profil variable et de preemption permettent la prise en compte d'aleas comme les pannes de machines. Les methodes utilisees pour construire l'ordonnancement doivent egalement faire preuve de flexibilite face a ces aleas, aussi avons-nous choisi d'etudier les algorithmes de liste. Nous les adaptons aux profils variables, avant de mettre en evidence les sous-problemes pour lesquels ils fournissent une solution exacte. Nous effectuons une analyse de leurs performances dans le plus mauvais cas, et proposons une etude statistique de leur valeur moyenne. Enfin un algorithme de ce type est utilise pour le probleme de l'ordonnancement stochastique sur profil variable: les temps de service des taches suivent une meme loi exponentielle
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Sonono, Tofik. "Interoperable Retransmission Protocols with Low Latency and Constrained Delay : A Performance Evaluation of RIST and SRT." Thesis, KTH, Kommunikationssystem, CoS, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254897.
Full textAbstract:
The media industry has during the last decade migrated services from dedicated medianetworks to more shared resources and lately also the public internet and public data centers. Inorder to cater for such transition, several protocols have been designed to meet the demand forhigh-quality media transport over lossy infrastructure, protocols such as SRT and RIST. Thepurpose of Reliable Internet Stream Transport (RIST) and Secure Reliable Transport (SRT) is tohave all vendors of broadcasting equipment support an interoperable way of communication. Thelack of interoperability locks consumers into one particular vendor’s family of products - most oftenthis equipment only supports a proprietary technology. Interoperability creates a more competitivemarket space which benefits consumers and gives vendors an incentive to be more innovative intheir solutions. The purpose of this thesis is to assess the performance of these protocols by comparing theirperformance to a proprietary solution (named ÖÖÖ in this thesis and seen as an establishedsolution in the industry). The challenge is to test these protocols in a lab environment, but have theresults represent real-world use. For this, a large subset of samples is needed along with samplesmeasured over a long period. This sampling was made possible by writing a script which automatesthe sampling process. The results indicate that the versions of RIST and SRT tested in this thesis to some extentcompare well to the selected established protocol (ÖÖÖ). In many scenarios, SRT even did muchbetter, mainly when a line with a single feed was tested. For instance, when the network suffered a2% drop rate and utilized retransmission SRT performed the best and was the only protocol whichhad some samples where no packets were dropped during one hour of measurements. Whenrunning all three protocols at the same time, SRT also did the best in a network with up to 12% droprate. The results in this thesis should give a broadcaster an idea of which of these protocols willfulfill their requirements in a broadcast application.<br>I mediabranschen finns det en efterfrågan på utrustning som har inslag av interoperabilitet.Anledningen till detta är att någon som köper produkter från en viss återförsäljare inte vill låsas in idenna återförsäljares ”ekosystem” i flera år framöver. Då en studio sällan uppgraderar hela sinproduktionskedja på samma gång ger interoperabilitet möjligheten att köpa utrustning från andraåterförsäljare när man ska uppgradera något i produktionslinan. Detta leder till en merkonkurrenskraftig marknad samt ger incentiv till nya innovativa lösningar. Detta examensarbete går ut på att utvärdera lösningar som tagits fram för att främjainteroperabilitet och jämföra dem med en existerande proprietärlösning. Reliable Internet StreamTransport (RIST) och Secure Reliable Transport (SRT) är två protokoll som tagits fram för just dettasyfte. Utmaningen med att utvärdera dessa protokoll är att i en labbmiljö få resultat som reflekteraranvändandet av protokollen i verkligheten. Detta har gjorts med hjälp av ett program som tagitsfram i detta examensarbete. Med detta program har testandet kunnat automatiseras. Resultaten i detta examensarbete visar potential hos båda RIST och SRT. SRT är i vissascenarion till och med bättre än den proprietära lösningen. Protokollen visar något buggigtbeteende i vissa instanser, såsom att i vissa fal sluta fungera och inte kunna återgå till normalfunktion utan manuell interaktion. Allt som allt är dock protokollen i de flesta fallen testade i dettaexamensarbete ett godtyckligt alternativ till den jämförda proprietära lösningen.
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Kuri, Joy. "Optimal Control Problems In Communication Networks With Information Delays And Quality Of Service Constraints." Thesis, Indian Institute of Science, 1995. https://etd.iisc.ac.in/handle/2005/162.
Full textAbstract:
In this thesis, we consider optimal control problems arising in high-speed integrated communication networks with Quality of Service (QOS) constraints. Integrated networks are expected to carry a large variety of traffic sources with widely varying traffic characteristics and performance requirements. Broadly, the traffic sources fall into two categories: (a) real-time sources with specified performance criteria, like small end to end delay and loss probability (sources of this type are referred to as Type 1 sources below), and (b) sources that do not have stringent performance criteria and do not demand performance guarantees from the network - the so-called Best Effort Type sources (these are referred to as Type 2 sources below). From the network's point of view, Type 2 sources are much more "controllable" than Type 1 sources, in the sense that the Type 2 sources can be dynamically slowed down, stopped or speeded up depending on traffic congestion in the network, while for Type 1 sources, the only control action available in case of congestion is packet dropping. Carrying sources of both types in the same network concurrently while meeting the performance objectives of Type 1 sources is a challenge and raises the question of equitable sharing of resources. The objective is to carry as much Type 2 traffic as possible without sacrificing the performance requirements of Type 1 traffic.
We consider simple models that capture this situation. Consider a network node through which two connections pass, one each of Types 1 and 2. One would like to maximize the throughput of the Type 2 connection while ensuring that the Type 1 connection's performance objectives are met. This can be set up as a constrained optimization problem that, however, is very hard to solve. We introduce a parameter b that represents the "cost" of buffer occupancy by Type 2 traffic. Since buffer space is limited and shared, a queued Type 2 packet means that a buffer position is not available for storing a Type 1 packet; to discourage the Type 2 connection from hogging the buffer, the cost parameter b is introduced, while a reward for each Type 2 packet coming into the buffer encourages the Type 2 connection to transmit at a high rate.
Using standard on-off models for the Type 1 sources, we show how values can be assigned to the parameter b; the value depends on the characteristics of the Type 1 connection passing through the node, i.e., whether it is a Variable Bit Rate (VBR) video connection or a Continuous Bit Rate (CBR) connection etc. Our approach gives concrete networking significance to the parameter b, which has long been considered as an abstract parameter in reward-penalty formulations of flow control problems (for example, [Stidham '85]).
Having seen how to assign values to b, we focus on the Type 2 connection next. Since Type 2 connections do not have strict performance requirements, it is possible to defer transmitting a Type 2 packet, if the conditions downstream so warrant. This leads to the question: what is the "best" transmission policy for Type 2 packets? Decisions to transmit or not must be based on congestion conditions downstream; however, the network state that is available at any instant gives information that is old, since feedback latency is an inherent feature of high speed networks. Thus the problem is to identify the best transmission policy under delayed feedback information.
We study this problem in the framework of Markov Decision Theory. With appropriate assumptions on the arrivals, service times and scheduling discipline at a network node, we formulate our problem as a Partially Observable Controlled Markov Chain (PO-CMC). We then give an equivalent formulation of the problem in terms of a Completely Observable Controlled Markov Chain (CO-CMC) that is easier to deal with., Using Dynamic Programming and Value Iteration, we identify structural properties of an optimal transmission policy when the delay in obtaining feedback information is one time slot. For both discounted and average cost criteria, we show that the optimal policy has a two-threshold structure, with the threshold on the observed queue length depending, on whether a Type 2 packet was transmitted in the last slot or not.
For an observation delay k > 2, the Value Iteration technique does not yield results. We use the structure of the problem to provide computable upper and lower bounds to the optimal value function. A study of these bounds yields information about the structure of the optimal policy for this problem. We show that for appropriate values of the parameters of the problem, depending on the number of transmissions in the last k steps, there is an "upper cut off" number which is a value such that if the observed queue length is greater than or equal to this number, the optimal action is to not transmit. Since the number of transmissions in the last k steps is between 0 and A: both inclusive, we have a stack of (k+1) upper cut off values. We conjecture that these (k + l) values axe thresholds and the optimal policy for this problem has a (k + l)-threshold structure.
So far it has been assumed that the parameters of the problem are known at the transmission control point. In reality, this is usually not known and changes over time. Thus, one needs an adaptive transmission policy that keeps track of and adjusts to changing network conditions. We show that the information structure in our problem admits a simple adaptive policy that performs reasonably well in a quasi-static traffic environment.
Up to this point, the models we have studied correspond to a single hop in a virtual connection. We consider the multiple hop problem next. A basic matter of interest here is whether one should have end to end or hop by hop controls. We develop a sample path approach to answer this question. It turns out that depending on the relative values of the b parameter in the transmitting node and its downstream neighbour, sometimes end to end controls are preferable while at other times hop by hop controls are preferable.
Finally, we consider a routing problem in a high speed network where feedback information is delayed, as usual. As before, we formulate the problem in the framework of Markov Decision Theory and apply Value Iteration to deduce structural properties of an optimal control policy. We show that for both discounted and average cost criteria, the optimal policy for an observation delay of one slot is Join the Shortest Expected Queue (JSEQ) - a natural and intuitively satisfactory extension of the well-known Join the Shortest Queue (JSQ) policy that is optimal when there is no feedback delay (see, for example, [Weber 78]). However, for an observation delay of more than one slot, we show that the JSEQ policy is not optimal. Determining the structure of the optimal policy for a delay k>2 appears to be very difficult using the Value Iteration approach; we explore some likely policies by simulation.
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Kuri, Joy. "Optimal Control Problems In Communication Networks With Information Delays And Quality Of Service Constraints." Thesis, Indian Institute of Science, 1995. http://hdl.handle.net/2005/162.
Full textAbstract:
In this thesis, we consider optimal control problems arising in high-speed integrated communication networks with Quality of Service (QOS) constraints. Integrated networks are expected to carry a large variety of traffic sources with widely varying traffic characteristics and performance requirements. Broadly, the traffic sources fall into two categories: (a) real-time sources with specified performance criteria, like small end to end delay and loss probability (sources of this type are referred to as Type 1 sources below), and (b) sources that do not have stringent performance criteria and do not demand performance guarantees from the network - the so-called Best Effort Type sources (these are referred to as Type 2 sources below). From the network's point of view, Type 2 sources are much more "controllable" than Type 1 sources, in the sense that the Type 2 sources can be dynamically slowed down, stopped or speeded up depending on traffic congestion in the network, while for Type 1 sources, the only control action available in case of congestion is packet dropping. Carrying sources of both types in the same network concurrently while meeting the performance objectives of Type 1 sources is a challenge and raises the question of equitable sharing of resources. The objective is to carry as much Type 2 traffic as possible without sacrificing the performance requirements of Type 1 traffic.
We consider simple models that capture this situation. Consider a network node through which two connections pass, one each of Types 1 and 2. One would like to maximize the throughput of the Type 2 connection while ensuring that the Type 1 connection's performance objectives are met. This can be set up as a constrained optimization problem that, however, is very hard to solve. We introduce a parameter b that represents the "cost" of buffer occupancy by Type 2 traffic. Since buffer space is limited and shared, a queued Type 2 packet means that a buffer position is not available for storing a Type 1 packet; to discourage the Type 2 connection from hogging the buffer, the cost parameter b is introduced, while a reward for each Type 2 packet coming into the buffer encourages the Type 2 connection to transmit at a high rate.
Using standard on-off models for the Type 1 sources, we show how values can be assigned to the parameter b; the value depends on the characteristics of the Type 1 connection passing through the node, i.e., whether it is a Variable Bit Rate (VBR) video connection or a Continuous Bit Rate (CBR) connection etc. Our approach gives concrete networking significance to the parameter b, which has long been considered as an abstract parameter in reward-penalty formulations of flow control problems (for example, [Stidham '85]).
Having seen how to assign values to b, we focus on the Type 2 connection next. Since Type 2 connections do not have strict performance requirements, it is possible to defer transmitting a Type 2 packet, if the conditions downstream so warrant. This leads to the question: what is the "best" transmission policy for Type 2 packets? Decisions to transmit or not must be based on congestion conditions downstream; however, the network state that is available at any instant gives information that is old, since feedback latency is an inherent feature of high speed networks. Thus the problem is to identify the best transmission policy under delayed feedback information.
We study this problem in the framework of Markov Decision Theory. With appropriate assumptions on the arrivals, service times and scheduling discipline at a network node, we formulate our problem as a Partially Observable Controlled Markov Chain (PO-CMC). We then give an equivalent formulation of the problem in terms of a Completely Observable Controlled Markov Chain (CO-CMC) that is easier to deal with., Using Dynamic Programming and Value Iteration, we identify structural properties of an optimal transmission policy when the delay in obtaining feedback information is one time slot. For both discounted and average cost criteria, we show that the optimal policy has a two-threshold structure, with the threshold on the observed queue length depending, on whether a Type 2 packet was transmitted in the last slot or not.
For an observation delay k > 2, the Value Iteration technique does not yield results. We use the structure of the problem to provide computable upper and lower bounds to the optimal value function. A study of these bounds yields information about the structure of the optimal policy for this problem. We show that for appropriate values of the parameters of the problem, depending on the number of transmissions in the last k steps, there is an "upper cut off" number which is a value such that if the observed queue length is greater than or equal to this number, the optimal action is to not transmit. Since the number of transmissions in the last k steps is between 0 and A: both inclusive, we have a stack of (k+1) upper cut off values. We conjecture that these (k + l) values axe thresholds and the optimal policy for this problem has a (k + l)-threshold structure.
So far it has been assumed that the parameters of the problem are known at the transmission control point. In reality, this is usually not known and changes over time. Thus, one needs an adaptive transmission policy that keeps track of and adjusts to changing network conditions. We show that the information structure in our problem admits a simple adaptive policy that performs reasonably well in a quasi-static traffic environment.
Up to this point, the models we have studied correspond to a single hop in a virtual connection. We consider the multiple hop problem next. A basic matter of interest here is whether one should have end to end or hop by hop controls. We develop a sample path approach to answer this question. It turns out that depending on the relative values of the b parameter in the transmitting node and its downstream neighbour, sometimes end to end controls are preferable while at other times hop by hop controls are preferable.
Finally, we consider a routing problem in a high speed network where feedback information is delayed, as usual. As before, we formulate the problem in the framework of Markov Decision Theory and apply Value Iteration to deduce structural properties of an optimal control policy. We show that for both discounted and average cost criteria, the optimal policy for an observation delay of one slot is Join the Shortest Expected Queue (JSEQ) - a natural and intuitively satisfactory extension of the well-known Join the Shortest Queue (JSQ) policy that is optimal when there is no feedback delay (see, for example, [Weber 78]). However, for an observation delay of more than one slot, we show that the JSEQ policy is not optimal. Determining the structure of the optimal policy for a delay k>2 appears to be very difficult using the Value Iteration approach; we explore some likely policies by simulation.
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Avila, Gastón. "Asymptotic staticity and tensor decompositions with fast decay conditions." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5404/.
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Corvino, Corvino and Schoen, Chruściel and Delay have shown the existence of a large class of asymptotically flat vacuum initial data for Einstein's field equations which are static or stationary in a neighborhood of space-like infinity, yet quite general in the interior. The proof relies on some abstract, non-constructive arguments which makes it difficult to calculate such data numerically by using similar arguments.
A quasilinear elliptic system of equations is presented of which we expect that it can be used to construct vacuum initial data which are asymptotically flat, time-reflection symmetric, and asymptotic to static data up to a prescribed order at space-like infinity. A perturbation argument is used to show the existence of solutions. It is valid when the order at which the solutions approach staticity is restricted to a certain range.
Difficulties appear when trying to improve this result to show the existence of solutions that are asymptotically static at higher order. The problems arise from the lack of surjectivity of a certain operator.
Some tensor decompositions in asymptotically flat manifolds exhibit some of the difficulties encountered above. The Helmholtz decomposition, which plays a role in the preparation of initial data for the Maxwell equations, is discussed as a model problem. A method to circumvent the difficulties that arise when fast decay rates are required is discussed. This is done in a way that opens the possibility to perform numerical computations.
The insights from the analysis of the Helmholtz decomposition are applied to the York decomposition, which is related to that part of the quasilinear system which gives rise to the difficulties. For this decomposition analogous results are obtained. It turns out, however, that in this case the presence of symmetries of the underlying metric leads to certain complications. The question, whether the results obtained so far can be used again to show by a perturbation argument the existence of vacuum initial data which approach static solutions at infinity at any given order, thus remains open. The answer requires further analysis and perhaps new methods.<br>Corvino, Corvino und Schoen als auch Chruściel und Delay haben die Existenz einer grossen Klasse asymptotisch flacher Anfangsdaten für Einsteins Vakuumfeldgleichungen gezeigt, die in einer Umgebung des raumartig Unendlichen statisch oder stationär aber im Inneren der Anfangshyperfläche sehr allgemein sind. Der Beweis beruht zum Teil auf abstrakten, nicht konstruktiven Argumenten, die Schwierigkeiten bereiten, wenn derartige Daten numerisch berechnet werden sollen.
In der Arbeit wird ein quasilineares elliptisches Gleichungssystem vorgestellt, von dem wir annehmen, dass es geeignet ist, asymptotisch flache Vakuumanfangsdaten zu berechnen, die zeitreflektionssymmetrisch sind und im raumartig Unendlichen in einer vorgeschriebenen Ordnung asymptotisch zu statischen Daten sind. Mit einem Störungsargument wird ein Existenzsatz bewiesen, der gilt, solange die Ordnung, in welcher die Lösungen asymptotisch statische Lösungen approximieren, in einem gewissen eingeschränkten Bereich liegt.
Versucht man, den Gültigkeitsbereich des Satzes zu erweitern, treten Schwierigkeiten auf. Diese hängen damit zusammen, dass ein gewisser Operator nicht mehr surjektiv ist.
In einigen Tensorzerlegungen auf asymptotisch flachen Räumen treten ähnliche Probleme auf, wie die oben erwähnten. Die Helmholtzzerlegung, die bei der Bereitstellung von Anfangsdaten für die Maxwellgleichungen eine Rolle spielt, wird als ein Modellfall diskutiert. Es wird eine Methode angegeben, die es erlaubt, die Schwierigkeiten zu umgehen, die auftreten, wenn ein schnelles Abfallverhalten des gesuchten Vektorfeldes im raumartig Unendlichen gefordert wird. Diese Methode gestattet es, solche Felder auch numerisch zu berechnen. Die Einsichten aus der Analyse der Helmholtzzerlegung werden dann auf die Yorkzerlegung angewandt, die in den Teil des quasilinearen Systems eingeht, der Anlass zu den genannten Schwierigkeiten gibt. Für diese Zerlegung ergeben sich analoge Resultate. Es treten allerdings Schwierigkeiten auf, wenn die zu Grunde liegende Metrik Symmetrien aufweist. Die Frage, ob die Ergebnisse, die soweit erhalten wurden, in einem Störungsargument verwendet werden können um die Existenz von Vakuumdaten zu zeigen, die im räumlich Unendlichen in jeder Ordnung statische Daten approximieren, bleibt daher offen. Die Antwort erfordert eine weitergehende Untersuchung und möglicherweise auch neue Methoden.
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Sama, Aravind Reddy. "AOD²V : Ad Hoc On Demand and Delay Constrained Distance Vector Routing for mobile sensor/actor networks /." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1619624051&sid=12&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Vidović, Tin, and Lamija Hasanagić. "TIGHTER INTER-CORE DELAYS IN MULTI-CORE EMBEDDED SYSTEMS UNDER PARTITIONED SCHEDULING." Thesis, Mälardalens högskola, Inbyggda system, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-48575.
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There exists an increasing demand for computing power and performance in real-time embedded systems, as new, more complex customer requirements and function-alities are appearing every day. In order to support these requirements and func-tionalities without breaking the power consumption wall, many embedded systems areswitching from traditional single-core hardware architectures to multi-core architec-tures. Multi-core architectures allow for parallel execution of tasks on the multiplecores. This introduces many benets from the perspective of achievable performance,but in turn introduces major issues when it comes to the timing predictability ofthe real-time embedded system applications deployed on them. The problem arisesfrom unpredictable and potentially unbounded inter-core interferences, which occuras a result of contention for the shared resources, such as the shared system busor shared system memory. This thesis studies the possible application of constraintprogramming as a resource optimization technique for the purpose of creating oineschedules for tasks in real-time embedded system applications executing on a dual-core architecture. The main focus is placed on tightening inter-core data-propagationinterferences, which can result in lower over-all data-propagation delays. A proto-type of an optimization engine, employing constraint programming techniques on ap-plications comprised of tasks structured according to the Phased Execution Model isdeveloped. The prototype is evaluated through several experiments on a large numberof industry inspired intellectual-property free benchmarks. Alongside the experimentsa case study is conducted on an example engine-control application and the resultingschedule is compared to a schedule generated by the Rubus-ICE industrial tool suite.The obtained results show that the proposed method is applicable to a potentially widerange of abstract systems with dierent requirements. The limitations of the methodare also discussed and potential future work is debated based on these results.<br><p>Presentation was held over Zoom, due to the COVID-19 situation.</p>
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Franco, Duran Diana Marcela. "An Enhanced RCS Heuristic and an Enhanced RCPM Algorithm to Perform Delay Analysis in Schedules without Phantom Float." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/97570.
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On a regular basis, project managers concentrate their efforts on critical and near-critical activities. However, the concepts of total float and critical path lose their significance after applying resource-constrained scheduling (RCS) methodologies. RCS techniques solve the resource conflicts but create phantom float in the schedules (i.e., a float that does not exist). RCS techniques overlook the resources relationships between activities that compete for the same but unavailable resources. Therefore, each time an activity uses this apparent float (phantom float), there is a resource violation in the schedule.
Due to the projects' size and complexity, schedulers use scheduling software such as Primavera P6 to fix the resource conflicts of a schedule. The software correctly determines the activities' earliest dates that satisfy the resource limitations, but they calculate total float based on a "Time Context" ignoring the presence of resource constraints. Thus, the results show incorrect total float values and a broken critical path. The lack of a continuous critical path makes impossible the anticipation of the impact of a delaying event in the project completion time.
Several algorithms have been developed to address the shortcomings of RCS methods. These RCS related algorithms were developed with the aim of providing project managers a tool to correctly schedule and identify critical activities with respect to time and resource allocation and correctly calculate the total float of each activity under resource constraints. In this regard, the Resource-Constrained Critical Path Method (RCPM) is an algorithm that correctly calculates the floats of activities and identifies a continuous critical path in resource-constrained schedules.
Regardless of the RCPM provides more reliable float values than traditional RCS-related algorithms, there are some shortcomings that must be addressed to enhance its capability. This study addresses the existing shortcomings of RCPM to make it more practical for real construction projects.<br>Doctor of Philosophy<br>One of the challenges of resource allocation is resource availability because oftentimes, the resource demand exceeds the supply. When resources are over-allocated, activities are delayed until resources become available.
Due to the projects' size and complexity, schedulers use available software to solve the resource conflicts of a schedule. After testing Primavera P6 versions and MS Project v2016, both software create phantom float in a resource-constrained schedule. This is, the RCS calculations suggest that activities have float, but this float might not exist at all.
Resource-Constrained Scheduling (RCS) techniques mitigate a resource supply-demand problem but fail to identify a project critical path. The methods do not consider the resource-activity dependencies that arise when activities are delayed due to resource limits. As a result, the critical path is broken, and all the activities must be considered as critical.
To provide correct float values and a continuous critical path, the Resource-Constrained Critical Path (RCPM) was introduced by Kim and de la Garza in 2003. Regardless of the RCPM provides more reliable float values than traditional RCS-related algorithms, there are some shortcomings that must be addressed to enhance its capability. This study addresses the existing shortcomings of RCPM to make it more practical for real construction projects.
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Coelho, Jose Manuel dos Santos. "Underwater Acoustic Networks : evaluation of the impact of Media Access Control on latency, in a delay constrained network /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Mar%5FCoehlo.pdf.
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Gunaseelan, Nirmal K. "Quality of service analysis for hybrid-ARQ." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2720.
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Li, Ding. "Localised Routing Algorithms with Quality of Service Constraints. Development and performance evaluation by simulation of new localised Quality of Service routing algorithms for communication networks using residual bandwidth and mean end-to-end delay as metrics." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4912.
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Localised QoS routing is a relatively new, alternative and viable approach to solve the problems of traditional QoS routing algorithms which use global state information resulting in the imposition of a large communication overhead and route flapping. They make use of a localised view of the network QoS state in source nodes to select paths and route flows to destination nodes. Proportional Sticky Routing (PSR) and Credit Based Routing (CBR) have been proposed as localised QoS routing schemes and these can offer comparable performances. However, since network state information for a specific path is only updated when the path is used, PSR and CBR operate with decision criteria that are often stale for paths that are used infrequently. The aim of this thesis is to focus on localised QoS routing and contribute to enhancing the scalability of QoS routing algorithms. In this thesis we have developed three new localised QoS routing schemes which are called Score Based QoS Routing (SBR), Bandwidth Based QoS Routing (BBR) and Delay Based Routing (DBR). In some of these schemes, the path setup procedure is distributed and uses the current network state to make decisions thus avoiding problems of staleness. The methods also avoid any complicated calculations. Both SBR and BBR use bandwidth as the QoS metric and mean delay is used as the QoS metric in DBR. Extensive simulations are applied to compare the performance of our proposed algorithms with CBR and the global Dijkstra's algorithm for different update intervals of link state, different network topologies and using different flow arrival distributions under a wide range of traffic loads. It is demonstrated by simulation that the three proposed algorithms offer a superior performance under comparable conditions to the other localised and global algorithms.
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Aldosari, Fahd M. "New quality of service routing algorithms based on local state information : the development and performance evaluation of new bandwidth-constrained and delay-constrained quality of service routing algorithms based on localized routing strategies." Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5406.
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The exponential growth of Internet applications has created new challenges for the control and administration of large-scale networks, which consist of heterogeneous elements under dynamically changing traffic conditions. These emerging applications need guaranteed service levels, beyond those supported by best-effort networks, to deliver the intended services to the end user. Several models have been proposed for a Quality of Service (QoS) framework that can provide the means to transport these services. It is desirable to find efficient routing strategies that can meet the strict routing requirements of these applications. QoS routing is considered as one of the major components of the QoS framework in communication networks. In QoS routing, paths are selected based upon the knowledge of resource availability at network nodes and the QoS requirements of traffic. Several QoS routing schemes have been proposed that differ in the way they gather information about the network state and the way they select paths based on this information. The biggest downside of current QoS routing schemes is the frequent maintenance and distribution of global state information across the network, which imposes huge communication and processing overheads. Consequently, scalability is a major issue in designing efficient QoS routing algorithms, due to the high costs of the associated overheads. Moreover, inaccuracy and staleness of global state information is another problem that is caused by relatively long update intervals, which can significantly deteriorate routing performance. Localized QoS routing, where source nodes take routing decisions based solely on statistics collected locally, was proposed relatively recently as a viable alternative to global QoS routing. It has shown promising results in achieving good routing performance, while at the same time eliminating many scalability related problems. In localized QoS routing each source-destination pair needs to determine a set of candidate paths from which a path will be selected to route incoming flows. The goal of this thesis is to enhance the scalability of QoS routing by investigating and developing new models and algorithms based on the localized QoS routing approach. For this thesis, we have extensively studied the localized QoS routing approach and demonstrated that it can achieve a higher routing performance with lower overheads than global QoS routing schemes. Existing localized routing algorithms, Proportional Sticky Routing (PSR) and Credit-Based Routing (CBR), use the blocking probability of candidate paths as the criterion for selecting routing paths based on either flow proportions or a crediting mechanism, respectively. Routing based on the blocking probability of candidate paths may not always reflect the most accurate state of the network. This has motivated the search for alternative localized routing algorithms and to this end we have made the following contributions. First, three localized bandwidth-constrained QoS routing algorithms have been proposed, two are based on a source routing strategy and the third is based on a distributed routing strategy. All algorithms utilize the quality of links rather than the quality of paths in order to make routing decisions. Second, a dynamic precautionary mechanism was used with the proposed algorithms to prevent candidate paths from reaching critical quality levels. Third, a localized delay-constrained QoS routing algorithm was proposed to provide routing with an end-to-end delay guarantee. We compared the performance of the proposed localized QoS routing algorithms with other localized and global QoS routing algorithms under different network topologies and different traffic conditions. Simulation results show that the proposed algorithms outperform the other algorithms in terms of routing performance, resource balancing and have superior computational complexity and scalability features.
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Gürsu, Halit Murat [Verfasser], Wolfgang [Akademischer Betreuer] Kellerer, Wolfgang [Gutachter] Kellerer, and Cedomir [Gutachter] Stefanovic. "Delay-Constrained Reliable Cellular Uplink Radio Resource Management for Industrial Internet of Things / Halit Murat Gürsu ; Gutachter: Wolfgang Kellerer, Cedomir Stefanovic ; Betreuer: Wolfgang Kellerer." München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1232406066/34.
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Jackson, Paul Stephen. "The decay B± → Dâ°K*± bioremediation and constraints on the angle γ of the unitary triangle using the BABAR detector." Thesis, Royal Holloway, University of London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441383.
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Gungor, Onur. "INFORMATION THEORY ENABLED SECURE WIRELESS COMMUNICATION, KEY GENERATION AND AUTHENTICATION." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406298547.
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Lu, Hsiao-Heng, and 呂孝恆. "A Delay-constraint P2P Live Streaming System." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/07537607290441505845.
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碩士<br>國立交通大學<br>網路工程研究所<br>99<br>Nowadays, content distribution services comprise most of the Internet traffic, and about half of them is contributed by video streaming. Live streaming (LS), which provides people a way to share what are currently happening in the world, will be one of the main streams of video services on the Internet. Playback delay, the time interval between events occur and the event video are watched by LS users, is the most important metric of LS systems. In this paper, we focus on providing LS services in tree-based P2P networks, so that systems could serve more users under high bandwidth requirement and maximum playback delay constraint. We proposed two algorithms: PCL algorithm, and local optimization algorithm. PCL places newly joining peers in the tree properly so that peers which contribute more upload bandwidth could experience lower playback delay, and local optimization aims to lower the average system playback delay in distributed manner. The simulation result indicates that our algorithms allow systems to serve more users than the system which adopts an algorithm that only considers playback delay. In addition to the simulation work, we have implemented a tree-based P2P LS prototype, which allows us to verify/improve the future proposed algorithms in real Internet.
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Chen, Po-Lin, and 陳柏霖. "The Automation of Constraint Extraction for Functional Path Delay Fault Testing." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/80191467172360270377.
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碩士<br>國立清華大學<br>電機工程學系<br>92<br>With the advantages of at-speed testing, functional mode operation and low area overhead, functional self-test approach is wildly adopted nowadays for delay fault testing. However, modern designs will make this approach hard to apply due to large gate counts and complex functionality. Thus, a modified functional test flow is proposed by this paper to test processors and could be extended to ASICs. This flow includes circuit partition, constraints extraction, pattern generation and back-trace. Each part of the proposed flow is more automatic and effective than other method. The experiment result is demonstrated by testing Parwan processor. And the result showed is good by the proposed method.
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Wu, Sheng-Han, and 吳昇翰. "Maximizing Throughput for Delay-Constraint Transmissions with Smart Antenna System in WLANs." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/25381637154341253244.
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碩士<br>真理大學<br>資訊工程學系碩士班<br>99<br>A host can simultaneously transmit or receipt multiple packets on different beams with smart antenna (or Multi-beam antenna) systems. However, the host cannot transmit to its neighboring by one beam and receive from other neighboring by other beam simultaneously. Therefore, the transmission scheduling impacts the network performance. With delay constraints of transmission, this paper aims to develop transmission scheduling approaches with smart antenna systems for maximizing the network throughput based on the cluster topology. Initially, two approaches, named Sender-driven Parallel Transmission Procedure and Receiver-driven Parallel Transmission Procedure, build sets of parallel groups which are constructed for multi-beam smart antenna systems by the views of sender and receiver, respectively. Then we propose a scheduling algorithm for multiple transmissions on different beams simultaneously. The approaches also take the differences of transmission rate among simultaneous transmissions by one host into account. Performance study reveals that the proposed algorithm outperforms existing work in terms of network throughput and transmission guarantee.
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Jen, Liang Cheng. "A QoS -based HRWA multicast scheme with delay constraint on WDM mesh network." 2004. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0009-0112200611291141.
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Jen, Liang Cheng, and 梁正仁. "A QoS -based HRWA multicast scheme with delay constraint on WDM mesh network." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/83037556612061140926.
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碩士<br>元智大學<br>資訊工程學系<br>93<br>Many Internet multicast applications, such as teleconferencing and remote diagnosis, have Quality-of-Service (QoS) requirements. It is a challenging task to build QoS constrained multicast trees with high performance and high success ratio. The DWDM (Dense Wavelength Division Multiplex) can provide the high speed, high capacity transmission and the bandwidth efficiency to proceed with the multipoint-to-multipoint transmission service. Reserved paths with the form of tree are not the ideal topology for the multipoint-to-multipoint transmission service because transceivers and reserved wavelength channels will lead to some other meetings can not be held at the same time. This paper presents a new multicast algorithm Hybrid Routing and Wavelength Assignment with delay constraint (HRWA-DC) on WDM mesh network, which reduces the number of searching ring path to achieve low complexity. Simulation result shows the HRWA-DC has more effective for resource utilization than tree scheme in terms of lower call blocking probability and link utilization even in tight delay constraint. It is suited to big group size and long holding time of multipoint-to-multipoint multicast transmission.
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Wei-TsangHuang and 黃韋滄. "A Propotional Bandwidth Allocation Considering Delay Constraint for Wireless Mesh Networks Using IEEE 802.11e." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/09165262341496396968.
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Chou, Chien-Ming, and 周建銘. "Cross-Layer Based Delay-Constraint Adaptive Polling for High Density Subscribers in IEEE 802.16 WiMAX Networks." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/92258702146656588632.
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碩士<br>朝陽科技大學<br>網路與通訊研究所<br>95<br>The IEEE 802.16 standard (i.e., WiMAX) is proposed to support QoS-aware transmission of real-time service in Wireless Metropolitan Area Networks (WMANs). WiMAX also can operate as wireless backbone and cooperates with WiFi to form a heterogeneous wireless network. Thus, hot spots of WiFi belonged to different WiMAX networks can communicate with each other. For serving a large number of Subscriber Stations (SSs) within a Base Station (BS), WiMAX adopts the polling access control for a BS to poll SSs, and avoid occurring access collisions but causes long polling delay under a high-density SSs area. Thus, IEEE 802.16 does not serve real-time service (rtPS) while the BS is in multicast mode. This problem of long polling delay becomes worse when the BS serves a high-density SSs and only polls few SSs or groups once. Therefore, in this paper we propose an adaptive polling with a cross-layer mechanism approach to poll SSs dynamically among different polling modes while continuously supporting rtPS. The proposed approach consists of two phases. In the first phase, two hysteresises of number of SSs and residual bandwidth are adopted for determining the optimal polling mode for each connection. In the second phase, a novel QoS-aware rtPS service (QrtPS) that provides an Average Delay of real-time traffic instead of the Maximum Delay of rtPS is proposed to take over the rtPS service when a SS is polled by the multicast mode. Moreover, a cross-layer mechanism is proposed to achieve that such a real-time service can be sent with a high-quality or low-quality video codec when the SS is in unicast or multicast mode, respectively. Numerical results demonstrate that the proposed approach outperforms IEEE 802.16 in average delay and utilization significantly. Moreover, the collision probabilities of different contention slots and the number of groups within a BS are also evaluated for the multicast mode.
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En-RongHsu and 許恩榮. "Sleep Time Decision by First and Last Packet Arrival Time After REPORT in Ethernet Passive Optical Networks with Sleep Mode and Delay Constraint." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/98680153760722607193.
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碩士<br>國立成功大學<br>資訊工程學系<br>103<br>Abstract– Concerns about energy efficiency in the Ethernet passive optical network (EPON) are growing. In response, enabling optical network units (ONUs) to enter low-power sleep mode has become a focus in reducing energy consumption. However, in sleep mode, packets can not be transmitted, and so packet delays increase. Accordingly, the sleep time decision of when the ONU can enter sleep mode to conserve energy, yet not violate the delay constraints, becomes a challenge.
Green Bandwidth Allocation (GBA) was used to study the analytical model and propose a closed-form expression to determine the sleep time. In this manner, sleep time can be maximized for energy savings while simultaneously ensuring the average packet delay can satisfy the delay constraint. However, the packet arrival in the network may not be the same as the analytical assumption.
In this thesis, we start from determining the sleep time from a real-time information: first packet arrival time after REPORT message to keep packets satisfying delay constraint and meanwhile conserve energy as great as possible. Nevertheless, the sleep time decided by first packet arrival time causes a frequent transition overhead which wasted a lot of energy. Hence the last packet arrival time after REPORT message and a ratio parameter is added to enlarge sleep time so as to decrease transition overhead frequency. Since the OLT lacks packet arrival time information, the extension to the REPORT message carrying additional first and last packet arrival times after the last REPORT is sent to the OLT. Moreover, since the OLT needs to respond to the real-time arrival information, an on-line separated polling scheme and scheduling is presented. Simulation results showed that the percentage of packets violating the delay constraint can be lower than the GBA; however, the energy saving difference is no more than 1%.