Dissertations / Theses on the topic 'Control over networks'
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Ji, Kun. "Real-time control over networks." Texas A&M University, 2003. http://hdl.handle.net/1969.1/5834.
Full textAbebe, Zelalem Teffera. "Process Control over Wireless Sensor Networks." Thesis, KTH, Reglerteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-133584.
Full textZaidi, Ali Abbas. "Sensing and Control of Dynamical Systems Over Networks." Doctoral thesis, KTH, Kommunikationsteori, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-133337.
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梁鉅輝 and Kui-fai Leung. "Enhancing transmission control protocol performance over wireless networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31227570.
Full textEkman, Rasmus. "Automobile Control Systems : Transition from Controller Area Networks to Ethernets." Thesis, KTH, Radio Systems Laboratory (RS Lab), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-148052.
Full textDen negativa påverkan av fossila bränslen har de senaste årtionden haft en negativ på planeten, mängden fossila bränslen över världen konsumeras även i en högre takt än vad som produceras. Därför har fokusen för att finna förnybara energi källor som både är effektiva och inte påverkar miljön på ett negativt sätt ökat. Därför är elbilar en viktig del i konverteringen av enheter som drivs av fossila bränslen till förnybara energikällor. Ett av problemen i en elbil är att energi konsumptionen är inte lika effektiv som fossila bränslen inom bil industrin. Ett sätt att sänka energi konsumptionen är att minska mängden komponenter inom en bil för att minska på vikten, utan att påverka säkerheten och tillförlitligheten. Tidigare har man använt sig av ett CAN system för att försäkra sig om systemet fungerar felfritt i realtid, problematiken med detta system är att när nätverket ökar i storlek så sätter de fysiska begränsningarna av detta system stop för den garanterade säkerheten. Detta kandidatexamensarbete kommer att fokusera på den interna kommunikationen i en elbil med hjälp av ett ethernet baserat kommunkations system över CAN systemet. Power over Ethernet tekinken kommer att tillämpas för de systemen som kan drivas av detta system. Målet är att reducera antalet komponenter som behövs och att garantera säkerheten och tillförlitligheten av den interna kommunikationen när nätverket av komponenter ökar i storlek. Det här kandidatarbetet visar att Ethernet kan ersätta det nuvarande CAN systemet ef-tersom att Ethernet erbjuder låga latenser och hög bandbredd. Detta arbete visar även att Et-hernet är väldigt skalbart och har inte begränsingarna som ett CAN system har.
Li, Yuliang. "Congestion control for scalable video transmission over IP networks." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441312.
Full textChotikapong, Yotsapak. "TCP/IP and ATM over LEO satellite networks." Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/638/.
Full textShi, Xiaohan. "A reliable real-time transport protocol for networked control systems over wireless networks." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/60160/1/Xiaohan_Shi_Thesis.pdf.
Full textAlnuem, M. A. "Improving TCP performance over heterogeneous networks : the investigation and design of End to End techniques for improving TCP performance for transmission errors over heterogeneous data networks." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/3347.
Full textPesonen, Joonas. "Stochastic Estimation and Control over WirelessHART Networks: Theory and Implementation." Thesis, KTH, Reglerteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105172.
Full textLi, Ming. "Resource discovery and fair intelligent admission control over scalable Internet /." Electronic version, 2004. http://adt.lib.uts.edu.au/public/adt-NTSM20050314.180037/index.html.
Full textKang, Intae. "Topology control for broadcasting over energy constrained wireless ad hoc networks /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/6061.
Full textAlheraish, Abdulmohsen Abdulrahman. "Reliable VBR video communications using error control techniques over ATM networks." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248517.
Full textPerera, G. M. Ryan. "Error control for compressed video transmission over next generation mobile networks." Thesis, University of Surrey, 2018. http://epubs.surrey.ac.uk/844961/.
Full textAbdallah, AbouSheaisha Abdallah Sabry. "Cross-layer Control for Adaptive Video Streaming over Wireless Access Networks." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/78844.
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Sandberg, Henrik, Maben Rabi, Mikael Skoglund, and Karl Henrik Johansson. "Estimation over heterogeneous sensor networks." KTH, ACCESS Linnaeus Centre, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-30325.
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Bao, Lei. "Control over Low-Rate Noisy Channels." Doctoral thesis, KTH, Kommunikationsteori, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10641.
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Ors, Tolga. "Traffic and congestion control for ATM over satellite to provide QoS." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/843458/.
Full textHossain, Mohammad Istiak. "Designing Efficient Access Control to Comply Massive-Multiservice IoT over Cellular Networks." Licentiate thesis, KTH, Radio Systems Laboratory (RS Lab), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214974.
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Xu, Jianxuan. "Performance evaluation of TCP over optical channels and heterogeneous networks." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000314.
Full textHenriksson, Erik. "Compensating for Unreliable Communication Links in Networked Control Systems." Licentiate thesis, Stockholm : Skolan för elektro- och systemteknik, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11059.
Full textJia, Guihua. "Performance evaluation of congestion control protocols and loss differentiation algorithms over wireless networks." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27857.
Full textKasiolas, Anastasios. "Intelligent control in multimedia traffic policing, shaping and congestion avoidance over broadband networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ39837.pdf.
Full textBuse, D. P. "Information management, condition monitoring and control of power systems over internet protocol networks." Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402263.
Full textKesavareddigari, Himaja. "Analysis and Control of the Propagation of Failures and Misinformation over Complex Networks." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1588320404278331.
Full textJavadtalab, Abbas. "An End-to-End Solution for High Definition Video Conferencing over Best-Effort Networks." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/31954.
Full textIbrahim, Abdulkareem B. "Error resilience and concealment in MVC video over wireless networks." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/10484.
Full textBegen, Ali C. "Enhancing the Multimedia Experience in Emerging Networks." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14010.
Full textAbuhaija, Belal Saleh. "A simulation framework for service continuity over multi access wireless networks." Thesis, University of South Wales, 2010. https://pure.southwales.ac.uk/en/studentthesis/a-simulation-framework-for-service-continuity-over-multi-access-wireless-networks(5b370ae0-47b2-43b7-b0f2-91b1fd5fd3b8).html.
Full textMushtaq, Mubashar. "QoS provisioning for adaptive video streaming over P2P networks." Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13744.
Full textThere is an increasing demand for scalable deployment of real-time multimedia streaming applications over Internet. In this context, Peer-to-Peer (P2P) networks are playing an important role for supporting robust and large-scale transmission of multimedia content to heterogeneous clients. However, the deployment of real-time video streaming applications over P2P networks arises lot of challenges due to heterogeneity of terminals and access networks, dynamicity of peers, and other problems inherited from IP network. Real-time streaming applications are very sensitive to packet loss, jitter / transmission delay, and available end-to-end bandwidth. These elements have key importance in QoS provisioning and need extra consideration for smooth delivery of video streaming applications over P2P networks. Beside the abovementioned issues, P2P applications lack of awareness in constructing their overlay topologies and do not have any explicit interaction with service and network providers. This situation leads to inefficient utilization of network resources and may cause potential violation of peering agreements between providers. The aim of this thesis is to analyze these issues and to propose an adaptive real-time transport mechanism for QoS provisioning of Scalable Video Coding (SVC) applications over P2P networks. Our contributions in this dissertation are threefold. First, we propose a hybrid overlay organization mechanism allowing intelligent organization of sender peers based on network-awareness, media- awareness, and quality-awareness. This overlay organization is further used for an appropriate selection of best sender peers, and the efficient switching of peers to ensure a smooth video delivery when any of the sender peers is no more reliable. Second, we propose a packet video scheduling mechanism to assign different parts of the video content to specific peers. Third, we present a service provider driven P2P network framework that enables effective interaction between service / network providers and P2P applications to perform QoS provisioning mechanism for the video streaming
Almadi, Soloman Moses. "Converged IP-over-standard ethernet progress control networks for hydrocarbon process automation applications controllers." Thesis, Brunel University, 2011. http://bura.brunel.ac.uk/handle/2438/8365.
Full textGao, Chengwei. "Priority statistical multiplexing and two-level congestion control for video transmission over ATM networks /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/5889.
Full textCen, Song. "Congestion control and error concealment for real-time video transmission over Lossy Packet Networks /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3061641.
Full textHsiao, Hsu-Feng. "Multimedia streaming congestion control over heterogeneous networks : from distributed computation and end-to-end perspectives /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/5946.
Full textFredholm, Kenth, and Kristian Nilsson. "Implementing an application for communication and quality measurements over UMTS networks." Thesis, Linköping University, Department of Electrical Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1666.
Full textThe interest for various multimedia services accessed via the Internet has been growing immensely along with the bandwidth available. A similar development has emerged in the 3G mobile network. The focus of this master thesis is on the speech/audio part of a 3G multimedia application. The purpose has been to implement a traffic generating tool that can measure QoS (Quality of Service) in 3G networks. The application is compliant to the 3G standards, i.e. it uses AMR (Adaptive Multi Rate), SIP (Session Initiation Protocol) and RTP (Real Time Transport Protocol). AMR is a speech compression algorithm with the special feature that it can compress speech into several different bitrates. SIP signalling is used so that different applications can agree on how to communicate. RTP carries the speech frames over the network, in order to provide features that are necessary for media/multimedia applications. Issues like perception of audio and QoS related parameters is also discussed, from the perspective of users and developers.
ITO, Maria Silvia. "A control – theoretic approach for adaptive streaming over HTTP." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/16342.
Full textMade available in DSpace on 2016-04-06T13:08:48Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) A CONTROL-THEORETIC APPROACH FOR ADAPTIVE STREAMING OVER HTT.pdf: 5118913 bytes, checksum: fc08706cd245c8c0de45e4db894cb0a5 (MD5) Previous issue date: 2015-08-24
FACEPE
Video applications account for a large percentage of Internet traffic, and their utilization tends to grow. In this scenario, multimedia providers are required to deliver video and/or audio content in a seamless manner, regardless of network conditions and client device capabilities. However, current commercial services are not efficient enough, and the academic proposals do not take full advantage of their potential. To this end, we propose a control-theoretic adaptive streaming over HTTP system, which adapts the video quality to the network conditions in a video session. With this system, we aim at delivering video with the highest Quality of Experience possible, while leveraging the available network resources. Our system is located at the client side, and comprises a control system and a state machine. Together, they select the video level that is requested to the server, a standard HTTP server, which sends video chunks as the client requests them. To select the control system and state machine that best fit our requirements, we perform several experiments with different parameter values combinations. Our parameter selection is accomplished in two steps, the last one resulting in the combination that best fits our needs. Then, we compare our system performance to an existent system in the academia. Our experimental results show the benefits of providing more aggressive decisions on the video quality selection. However, they also show that such aggressiveness may, sometimes, compromise the system performance. Overall, though, our system outperforms the baseline of our experiments.
A computação em nuvem é um paradigma computacional que vem sendo amplamente utilizado ao longo dos últimos anos devido as suas características de provisionamento de recursos de forma escalável, onde o usuário paga apenas por aquilo que consumir. Esse modelo computacional possibilita que diversos serviços sejam ofertados a partir da sua Infraestrutura como Serviço (IaaS - Infrastructure as a Service). Porém, a falha de componentes dos recursos da nuvem é algo bastante comum e que afeta diretamente a disponibilidade dos serviços que os utilizam. Garantir alta disponibilidade em serviços na nuvem é um desafio para provedores, que podem utilizar de técnicas como análise de sensibilidade para identificar gargalos de disponibilidade ou ainda fazer uso de mecanismos de tolerância à falhas para atingir melhores resultados de confiabilidade. Desse modo, esse trabalho tem como proposta realizar a avaliação de disponibilidade em arquiteturas para o provimento do serviço de VoD streaming na nuvem, baseado na plataforma Eucalyptus. O trabalho está dividido em dois estudos de caso. Primeiro, apresentamos uma arquitetura básica, sem mecanismos de redundância. Através de modelagem hierárquica formada por diagramas de blocos de confiabilidade (RBD - Reliability Block Diagram) e cadeias de Markov de tempo contínuo (CTMC - Continuous Time Markov Chain), realizamos a avaliação da disponibilidade para essa arquitetura, e em seguida alcançamos a validação do modelo que representa o funcionamento do serviço. Por fim, aplicamos a técnica de análise de sensibilidade paramétrica para identificar gargalos de disponibilidade na arquitetura básica. As análises seguintes que foram esse estudo de caso observam a disponibilidade do serviço em arquiteturas com redundância no modo warm-stand guiadas por índices de sensibilidade, apresentando ao final uma comparação dos valores de disponibilidade para cada arquitetura obtida a partir de componentes redundantes. O segundo estudo de caso analisa o comportamento da disponibilidade total do serviço a partir da variação no tempo de ativação dos mecanismos redundantes. Nossos resultados expressaram que a adoção de componentes redundantes no modo warm-stand na infraestrutura da nuvem proporciona ganhos de disponibilidade no serviço analisado. Também observamos que a variação do tempo de ativação do componente de maior confiabilidade tem maior impacto na disponibilidade total do serviço de VoD streaming.
Hussain, Khadim, and Choudhry Humayun Saleem. "Using Peer to Peer Over Wireless Ad Hoc Networks as an Emergency Command and Control System." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-2400.
Full textPeer-to-Peer networking technology is evolving rapidly. P2P networks overcome the limitations of client/server networks where each computer shares resources of other computer. There are different types of P2P networks depending upon their functionalities. Peer to peer networks provide long list of features like: selection of nearby peers, redundant storage, effi-cient search/location of data items, data performance or guarantees etc. It is important to see that how P2P can work with wireless ad hoc networks and why it is important. What are im-portant issues which come across by using P2P and wireless ad hoc networks together. How TCP/IP stack can be affected. How the whole system looks like in which P2P techniques are used with wireless ad hoc routing protocols to perform different tasks and services.
Dolz, Algaba Daniel. "Estimation and fault diagnosis strategies for networked control systems." Doctoral thesis, Universitat Jaume I, 2014. http://hdl.handle.net/10803/285103.
Full textFirst, we study the state estimation problem. Motivated by reducing the implementation computational load of Luenberger-type estimators, we focus on predefined gain approaches for different network transmission conditions.
In general, we propose jump estimators whose gains are related to the different network-induced data reception scenarios. We define the estimator complexity in terms of the number of different stored gains. Considering constant successful transmission probabilities, our main contribution here is the design of jump linear estimators to attain favorable trade-offs between estimation performance and estimator complexity. We show that one can reduce the estimator complexity while guaranteeing a similar performance than the optimal Kalman Filter. When dropouts are governed by a non-stationary stochastic process, the successful transmission probability is time-varying and may be unknown. For this case, we propose an estimator whose gains are scheduled in real-time with rational functions of the estimated packet arrival rate. We turn the design procedure into an optimization problem over polynomials that is numerically solved employing sum-of-squares (SOS) decomposition techniques.
Second, motivated by reducing the network resource consumption without considerably degrading the estimation performance, we study the jointly design of jump linear estimators and predefined network operation conditions (co-design) to guarantee a favorable trade-off. Focusing on wireless networks with self-powered nodes, where transmitting is the most energy consuming task, we analyze two approaches for the network operation: event-based transmissions and power control.
For the event-based approach, we use a Send-on-Delta protocol which reduces the number of transmissions with respect to transmitting at each sampling instant. However, it leads to an unknown successful transmission probability. For this framework, we contribute by characterizing this uncertainty and including it on the stochastic behavior of the estimator by means of a SOS-based design. Power control strategies are developed over a multi-hop wireless network with fading channels. Instead of reducing the number of transmission, power control acts directly on the transmission power. Higher transmission powers imply higher successful transmission probability values.
Finally, motivated by the need of assuring a reliable operation of the networked system, we study the fault diagnosis problem. We explore and point out the trade-offs between fast fault detection and fault tracking conditions. We design jump estimatorbased fault diagnosers in which we can specify the minimum detectable faults, false alarm rate and response time to faults. Another contribution is a tightened version of existing false alarm rate bounds.
Moreover, we also address the case when the control input is transmitted through a network without delivery acknowledgement. In this case, we improve fault diagnosisaccuracy by scheduling in real time the estimator jumping gains with rational functions that depend on a statistic of the control input error (difference between the control command being applied in the process and the one being used in the estimator). Again, we use a SOS-based solution approach to make the design problem tractable.
Sangal, Rahul. "Performance analysis of the transmission control protocol over low earth orbit satellite communication systems." Ohio University / OhioLINK, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1175629275.
Full textJayaram, Ranjith S. "Performance Evaluation of TEAR, a TCP-friendly Flow Control Protocol, Over the Internet and Wireless Networks." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010717-083717.
Full textTCP Emulation at Receivers (TEAR) is a TCP-friendly protocol that has been proposed for real-time multimedia flow control. Most best-effort traffic on the Internet is well-served by TCP, the dominant transport protocol. However, many applications with real-time constraints, such as multimedia streaming find TCP's response to congestion quite severe and too drastic to deliver acceptable end-user quality. TEAR was designed in order to provide smoothly varying rate changes for such applications while being friendly to competing TCP flows. In this thesis, weevaluate and verify TEAR's performance over the Internet. We verify TEAR's fairness to TCP, the smoothness of its rate fluctuations and its stability in the presence of network perturbations. We then adapt TEAR to run over wireless networks and consider using round-trip delay instead of packet loss as a congestion indication for wireless networks. We present the results of our experiments with TEAR over commercially deployed wireless networks in South Korea. We recount our experiences with the loss-delay characteristics of these networks. We analyze how TEAR competes with TCP, which is known to suffer from severe degradations in environments where the underlying network is unreliable. We then study TEAR's rate variations and the increased longer-term predictability it provides over wireless networks. Finally, we compare the performance of a reliable protocol we built over TEAR with TCP.
Li, Lian. "The design and implementation of a real-time multimedia synchronization control system over high-speed communications networks." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6738.
Full textLi, Zhi. "Fuzzy logic based robust control of queue management and optimal treatment of traffic over TCP/IP networks." University of Southern Queensland, Faculty of Sciences, 2005. http://eprints.usq.edu.au/archive/00001461/.
Full textCanovas, Sergio Roberto de Mello. "Integração entre redes LonWorks e redes IP: aplicações, requisitos e soluções." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3141/tde-22042007-142526/.
Full textControl networks utilization on automation systems has been increasing. Their interconnection with the Internet is also an interesting option, creating the necessity of new studies. This work considers the interconnection between LonWorks control networks and IP-based networks. Four categories of applications are the focus: remote monitoring of LonWorks networks thorugh IP networks; remote management of LonWorks networks through IP networks; use of an IP network as a backbone to interconnect more than one LonWorks network; and the same use of an IP network for applications with real time requirements. Four questions establish the escope of this study: what kinds of solutions are available to provide interconnection between LonWorks and IP networks; what kinds of network parameters should be considered in a LonWorks/IP based solution and how can they be used to determine requirements for an application; which are the most common requirements for each one of the four categories of applications; and which solution does best fit to each category. The answers of these questions were based on theoretical studies and experiments. The notation used in different references was unified, and basic concepts and elements about the topic were presented. New explanations, examples and considerations were also introduced. A software application to emulate a control loop running over LonWorks/IP networks has been developed. This tool can be used for tests and even as a start point for real projects. The main contributions of this work are: identification of quantitative network parameters for establishement of requirements of LonWorks/IP applications; creation of a software application to run a control loop over LonWorks/IP networks; analysis of current knowledge about LonWorks technology; and identification of relationships between technological solutions for LonWorks/IP interconnection and categories of application of the technology.
Garcia, Raul Murillo. "Development and evaluation of a novel tool for real-time control and remote monitoring over local area networks." Thesis, Glasgow Caledonian University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289677.
Full textLi, Yue. "Edge computing-based access network selection for heterogeneous wireless networks." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S042/document.
Full textTelecommunication network has evolved from 1G to 4G in the past decades. One of the typical characteristics of the 4G network is the coexistence of heterogeneous radio access technologies, which offers end-users the capability to connect them and to switch between them with their mobile devices of the new generation. However, selecting the right network is not an easy task for mobile users since access network condition changes rapidly. Moreover, video streaming is becoming the major data service over the mobile network where content providers and network operators should cooperate to guarantee the quality of video delivery. In order to cope with this context, the thesis concerns the design of a novel approach for making an optimal network selection decision and architecture for improving the performance of adaptive streaming in the context of a heterogeneous network. Firstly, we introduce an analytical model (i.e. linear discrete-time system) to describe the network selection procedure considering one traffic class. Then, we consider the design of a selection strategy based on foundations from linear optimal control theory, with the objective to maximize network resource utilization while meeting the constraints of the supported services. Computer simulations with MATLAB are carried out to validate the efficiency of the proposed mechanism. Based on the same principal we extend this model with a general analytical model describing the network selection procedures in heterogeneous network environments with multiple traffic classes. The proposed model was, then, used to derive a scalable mechanism based on control theory, which allows not only to assist in steering dynamically the traffic to the most appropriate network access but also helps in blocking the residual traffic dynamically when the network is congested by adjusting dynamically the access probabilities. We discuss the advantages of a seamless integration with the ANDSF. A prototype is also implemented into ns-3. Simulation results sort out that the proposed scheme prevents the network congestion and demonstrates the effectiveness of the controller design, which can maximize the network resources allocation by converging the network workload to the targeted network occupancy. Thereafter, we focus on enhancing the performance of DASH in a mobile network environment for the users which has one access network. We introduce a novel architecture based on MEC. The proposed adaptation mechanism, running as an MEC service, can modify the manifest files in real time, responding to network congestion and dynamic demand, thus driving clients towards selecting more appropriate quality/bitrate video representations. We have developed a virtualized testbed to run the experiment with our proposed scheme. The simulation results demonstrate its QoE benefits compared to traditional, purely client-driven, bitrate adaptation approaches since our scheme notably improves both on the achieved MOS and on fairness in the face of congestion. Finally, we extend the proposed the MEC-based architecture to support the DASH service in a multi-access heterogeneous network in order to maximize the QoE and fairness of mobile users. In this scenario, our scheme should help users select both video quality and access network and we formulate it as an optimization problem. This optimization problem can be solved by IBM CPLEX tool. However, this tool is time-consuming and not scalable. Therefore, we introduce a heuristic algorithm to make a sub-optimal solution with less complexity. Then we implement a testbed to conduct the experiment and the result demonstrates that our proposed algorithm notably can achieve similar performance on overall achieved QoE and fairness with much more time-saving compared to the IBM CPLEX tool
Grigorescu, Eduard. "Reducing internet latency for thin-stream applications over reliable transport with active queue management." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=236098.
Full textSfairopoulou, Anna. "A cross-layer mechanism for QoS improvements in VoIP over multi-rate WLAN networks." Doctoral thesis, Universitat Pompeu Fabra, 2008. http://hdl.handle.net/10803/7563.
Full textEn las redes inalámbricas del estándar IEEE 802.11, los mecanismos de adaptación de enlace que eligen la tasa de transmisión de cada nodo, pueden provocar variaciones aleatorias e inesperadas en la capacidad efectiva del canal. Cuando estos cambios son hacia tasas de transmisión mas bajas, los flujos inelásticos, tales como los de VoIP, pueden de repente sufrir congestión, lo que se traduce en aumento de retrasos y pérdidas de paquetes. En esa tesis, se propone un algoritmo de adaptación de codificadores de voz como solución, basado en técnicas multinivel (cross-layer) que combinan el uso de información de diferentes capas, como los paquetes RTCP y la capa MAC, y que puede adaptar los codecs de las llamadas activas para ajustarlos al escenario "multi-rate". Adicionalmente, la combinación de este algoritmo con un mecanismo de control de admisión de llamadas (CAC) se ha estudiado. Los resultados muestran una importante mejora en términos de QoS de los flujos activos como también en la capacidad total del hotspot. Además, mediante la definición de un nuevo factor, el Q-Factor, que puede captar la compensación entre la tasa de corte y de bloqueo de llamadas y de la calidad percibida por esas, el algoritmo de adaptación de codecs se puede ajustar para lograr la máxima capacidad sin penalizar severamente ninguna de esas variables y así satisfacer los requisitos técnicos de calidad y los usuarios. Por último, un nuevo punto de acceso (AP) habilitado para ofrecer calidad de servicio, ha sido diseñado que lleva a cabo estas mejoras.
Vittorias, Iason [Verfasser], Sandra [Akademischer Betreuer] Hirche, and Eckehard [Akademischer Betreuer] Steinbach. "Human-centered control design for haptic telepresence systems over communication networks / Iason Vittorias. Gutachter: Eckehard Steinbach ; Sandra Hirche. Betreuer: Sandra Hirche." München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1024161218/34.
Full textAhmed, Sabbir. "Performance of Multi-Channel Medium Access Control Protocol incorporating Opportunistic Cooperative Diversity over Rayleigh Fading Channel." Thesis, Blekinge Tekniska Högskola, Avdelningen för signalbehandling, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-6171.
Full textsabbir@linuxmail.org
Kalfas, Georgios. "Medium-transparent MAC protocols for converged optical wireless networks." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/406358.
Full textA fin de atender la demanda explosiva de alta capacidad y acceso inalámbrico omnipresente, las redes inalámbricas basadas en celdas están poco a poco adoptando dos principales guías de solución. La primera es el empleo de formaciones de celdas pequeñas con el fin de aumentar la eficiencia espectral global, mientras que la segunda es el empleo de bandas de frecuencia superior, como la banda de 60GHz, la cual ofrece una gran cantidad de ancho de banda. Dependiendo de la aplicación en específico, las soluciones anteriores inevitable-mente requieren de una instalación y una gestión operativa de grandes cantidades de Estaciones Base o Puntos de Acceso, que en última instancia disminuye la rentabilidad de la arquitectura. Para reducir el coste, la tecnología radioeléctrica por fibra (RoF) se presenta como una solución ideal debido al hecho de que proporciona unidades de antenas de sim-ple funcionamiento, a menudo denominadas Unidades de Antenas Remotas (RAUs), las cuales están interconectadas a una entidad central de gestión, denominada Oficina Central (CO), a través de la fibra óptica. A pesar de que se han dedicado muchos esfuerzos de investigación al desarrollo de varios aspectos de las capas física con respecto a las tecnologías RoF, muy pocos esfuerzos se han concentrado en la capa superior y cuestiones de gestión de recursos. En esta tesis, nos enfocando en el control de acceso y gestión de recursos de arquitecturas RoF y comunicaciones milimétricas, con el fin de aprovechar y explotar el medio dual y las propiedades para realizar una óptima asignación de los recursos ópticos, inalámbricos y temporales. Nosotros proponemos un protocolo Transparente al Medio MAC (MT-MAC) que simultáneamente administre los recursos ópticos e inalámbricos de una red RoF a 60GHz, conectando a la perfección el CO a los terminales inalámbricos a través de una mínima intervención RAU. El protocolo MT-MAC forma unas redes WLAN 60GHz de alcance extendido, ofreciendo así conectividad entre los dispositivos inalámbricos que están conectados al mismo o diferentes RAUs bajo con o sin Línea de Vista (condiciones LOS o NLOS) respectivamente. La noción de transparencia al medio se basa en dos períodos de contención para-lelos, el primero en el dominio óptico y el segundo en la frecuencia inalámbrica y dominio del tiempo, con estructuras de datos anidados. La operación MT-MAC se basa en proponer un diseño RAU que permita la selectividad de funciones de longitud de onda. Dos variantes del protocolo MT- MAC son considerados; el primer ofrece asignación de longitud de onda dinámica con ventanas de tiempo fijo, mientras que la segunda tiene como objetivo entornos de aplicaciones sensibles ofreciendo asignación de longitud de onda con tamaño de ventana de oportunidad de transmisión dinámico, basado en el número de clientes conectados en cada RAU. Ambas variantes del protocolo están evaluadas tanto por medios analíticos como de simulación. En la segunda parte, esta tesis introduce dos modelos analíticos para calcular el rendimiento de saturación y no saturación del retardo de paquetes para el protocolo MT-MAC convergente. Finalmente, esta tesis presenta un extenso estudio de la planificación de red y la formación de redes 60GHz Gigabit WLAN cuando esta se encuentra desplegada sobre las ya existente infraestructuras de Redes Ópticas Pasivas (PONs). Tres posibles arquitecturas han sido estudiadas: i) el enfoque RoF, ii) el enfoque Radio y Fibra , y iii) el enfoque híbrido, RoF más R&F el cual combina las propiedades de ambas arquitecturas anteriormente mencionadas. Durante la elaboración de esta tesis, se ha extraído una importante conclusión: hay un requerimiento fundamental para implementar nuevos protocolos ópticos/inalámbricos convergentes, que tengan una completa visión de ambos recursos disponibles para poder administrar efectivamente las redes de tecnología RoF.