Dissertations / Theses on the topic 'Congestion control algorithms'
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Edwan, Talal A. "Improved algorithms for TCP congestion control." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/7141.
Bhandarkar, Sumitha. "Congestion control algorithms of TCP in emerging networks." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1757.
Voice, Thomas David. "Stability of congestion control algorithms with multi-path routing and linear stochastic modelling of congestion control." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614022.
Lai, Chengdi, and 賴成迪. "Systematic design of internet congestion control : theory and algorithms." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206356.
published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
Chen, Hanliu. "Performance evaluation and analysis of datagram congestion control algorithms in IP networks." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27964.
Jia, 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.
Özbay, Kaan. "A framework for dynamic traffic diversion during non-recurrent congestion: models and algorithms." Diss., Virginia Tech, 1996. http://hdl.handle.net/10919/39210.
Ph. D.
Braga, Andrà Ribeiro. "Controle de congestionamento para voz sobre IP em HSDPA." Universidade Federal do CearÃ, 2006. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=2073.
O crescimento do nÃmero dos usuÃrios do serviÃo de Voice over IP(VoIP) faz dele o serviÃo com o maior interesse de ser provido por operadoras de telefonia celular. Por outro lado, este demanda um controle de Quality of Service (QoS) bastante rÃgido, o que torna-se mais complicado em redes sem fio, porque alÃm de congestionamentos na rede, os pacotes podem ser perdidos devido à erros nas transmissÃes no enlace de rÃdio. Dentro deste paradigma, estratÃgias de controle de congestionamento aparecem como uma boa soluÃÃo para lidar com as garantias de QoS em situaÃÃes de sobrecarga do sistema, onde os recursos se encontram exauridos e os requerimentos de qualidade se encontram ameaÃados. Este trabalho consiste na avaliaÃÃo de algoritmos de controle de congestionamento objetivando um aumento de capacidade e das garantias de QoS para serviÃos de voz. Os algoritmos avaliados neste trabalho sÃo os escalonamentos de pacotes e os controles de admissÃo. A anÃlise em cenÃrios de serviÃos mistos composto por usuÃrios VoIP e Web tambÃm està contida neste trabalho. O maior foco està no controle do atraso de pacote, jà que este à um requerimento crucial para serviÃos de tempo-real, como o VoIP. Os resultados mostram que um arcabouÃo de controle de congestionamento projetado para este serviÃo à capaz de melhorar o desempenho do sistema e mitigar os efeitos de congestionamento da rede. No cenÃrio de serviÃos mistos, os algoritmos sÃo capazes de efetuar reserva de recursos dependendo da prioridade definida para cada serviÃo, levando a um aumento na qualidade percebida pelo serviÃo mais sensÃvel atravÃs de uma leve degradaÃÃo no serviÃo mais robusto.
The growth in the number of Voice over IP(VoIP) users on the internet makes it the service with the highest interest to be provided by cellular operators. On the other hand, it demands very strict Quality of Service (QoS) control, which becomes even more complicated in wireless networks, because packets can be lost due to radio link transmission erros, as well as networks congestion. Within this paradigm, congestion control strategies appear as a good solution to cope with QoS guarantees under high loads, where the resources are exhausted and the service quality is threatened. This works comprises the evaluation of congestion control algorithms aiming to improve system capacity and QoS guarantees for speech users. The evaluated alagorithms within this work are packet scheduling and admission control. The analysys in mixed services scenarios composed of VoIP and Web users is also provid in this works. The main focus of the framework is to control the packet delay, since it is a crucial requirement for real-time services. The results show thata suitable congestion control framework is able to provid perfomace improvements and mitigation of the the effects from overloaded conditions. In the mixed services scenario, the algorithms are capable to perform resource reservation depending on the priority defined to each service, leanding to an increase in the quality of more sensitive service by degrading the more robust service
TRAVERSO, STEFANO. "Design of Algorithms and Protocols for Peer-To-Peer Streaming Systems." Doctoral thesis, Politecnico di Torino, 2012. http://hdl.handle.net/11583/2497192.
Roverso, Roberto. "A System, Tools and Algorithms for Adaptive HTTP-live Streaming on Peer-to-peer Overlays." Doctoral thesis, KTH, Programvaruteknik och Datorsystem, SCS, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134351.
QC 20131122
Figueiredo, Ricardo Nogueira de. "Avaliação de algoritmos de controle de congestionamento como controle de admissão em um modelo de servidores web com diferenciação de serviços." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-18052011-112317/.
This MSc dissertation presents the implementation of a prototype for a distributed web server based on the SWDS, a model for a web server with service differentiation, and the implementation and evaluation of selection algorithms adopting the concept of congestion control for HTTP requests. Thus, besides implementing a test platform this work also evaluates the behavior of two congestion control algorithms. The two algorithms studied are the Drop Tail and the RED (Random Early Detection), which are frequently discussed in the scientific literature and widely applied in computer networks. The results obtained show that, although the particularities of each algorithm, there is a strong relation between the response times and the amount of requests accepted in the server
Tlaiss, Ziad. "Automated network packet traces analysis methods for fault recognition and TCP flavor identification." Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2023. http://www.theses.fr/2023IMTA0384.
In recent years, the field of network troubleshooting has garnered significant attention from researchers due to the complexity and importance of this task. The work presented in this thesis focuses on automating network troubleshooting using performance metrics extracted from packet captures. The first contribution of this thesis lies in extracting features to identify the root cause of an anomaly by analyzing TCP packet traces with bad performance. We have categorized four frequently observed causes of degradation: transmission problems, congestion problems, jitter problems, and application-limited problems. The second contribution of this thesis involves developing an automated method to detect the moment of exiting the Slow-Start state. The significance of this method lies in saving valuable time in the analysis of network degradation, as the Slow-Start state serves as a key indicator for fault diagnosis. The third contribution of this thesis revolves around identifying the BBR congestion control algorithm. The primary goal of our approach is to detect whether packet pacing is employed in a TCP connection. This method relies on modeling the distribution of inter-packet duration during the Slow-Start state. The objective is to distinguish unimodal distributions of inter-packet intervals in the case of BBR compared to mixed two component distributions in the case of CUBIC
Soua, Ahmed. "Vehicular ad hoc networks : dissemination, data collection and routing : models and algorithms." Phd thesis, Institut National des Télécommunications, 2013. http://tel.archives-ouvertes.fr/tel-00919774.
Soua, Ahmed. "Vehicular ad hoc networks : dissemination, data collection and routing : models and algorithms." Electronic Thesis or Diss., Evry, Institut national des télécommunications, 2013. http://www.theses.fr/2013TELE0028.
Each day, Humanity loses thousands of persons on roads when they were traveling to work, to study or even to distract. The financial cost of these injuries is also terrifying: Some statistics evaluate the financial cost of vehicle accidents at 160 billion Euro in Europe each year. These alarming figures have driven researchers, automotive companies and public governments to improve the safety of our transportation systems and communication technologies aiming at offering safer roads and smooth driving to human beings. In this context, Vehicular Adhoc Networks, where vehicles are able to communicate with each others and with existent road side units, emerge as a promising wireless technology able to enhance the vision of drivers and offer larger telematic horizon. VANETs promising applications are not only restricted to road safety but span from vehicle trafficoptimization like flow congestion control to commercial applications like file sharing and internet access. Safety applications require that their alert information is propagated to the concerned vehicles (located in the hazardous zone) with little delay and high reliability. For these reasons, this category of applications is considered as delay sensitive and broadcast-oriented nature. While classical blind flooding is rapid, its major drawback is its huge bandwidth utilization. In this thesis, we are interested on enhancing vehicular communications under different scenarios and optimizations: First, We focus on deriving a new solution (EBDR) to disseminate alert messages among moving vehicles while maintaining it efficient and rapid. Our proposal is based on directional antennas to broadcast messages and a route guidance algorithm to choose the best path for the packets. Findings confirmed the efficiency of our approach in terms of probability of success and end-to-end delays. Moreover, in spite of the broadcast nature of the proposed technique, all transmissions stop very soon after the arrival of a packet to its destination representing a strong feature in the conception of EBDR. Second, we propose a novel mathematical framework to evaluate the performance of EBDR analytically. Although most of the proposed techniques present in literature use experimental or simulation tools to defend their performance, we rely here on mathematical models to confirm our achieved results. Our proposed framework allows to derive meaningful performance metrics including the probability of transmission success and the required number of hops to reach thefinal destination. Third, we refine our proposed broadcast-based routing EBDR to provide more efficient broadcasting by adjusting the transmission range of each vehicle based on its distance to the destination and the local node density. This mechanism allows better minimization of interferences and bandwidth's saving. Furthermore, an analytical model is derived to calculate thetransmission area in the case of a simplified node distribution. Finally, we are interested on data collection mechanisms as they make inter-vehicle communications more efficient and reliable and minimize the bandwidth utilization. Our technique uses Q-learning to collect data among moving vehicles in VANETs. The aim behind using the learning technique is to make the collecting operation more reactive to nodes mobility and topology changes. For the simulation part, we compare it to a non-learning version to study the effect of the learning technique. Findings show that our technique far outperforms other propositions and achieves a good trade off between delay and collection ratio. In conclusion, we believe that the different contributions presented in this Thesis will improve the efficiency of inter-vehicle communications in both dissemination and data collection directions. In addition, our mathematical contributions will enrich the literature in terms of constructing suitable models to evaluate broadcasting techniques in urban zones
Robert, Remi. "Comparative study of the performance of TCP congestion control algorithms in an LTE network : A simulation approach to evaluate the performance of different TCP implementations in an LTE network." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187983.
På grund av utvecklingen av smartphones blev data den största källan av traffik i aktuella mobilnätverk. Den här uppsatsen handlar om jämförelsen av utförandet av olika TCP Congestion Control Algorithms när de används i LTE nätverk. Vi utveklade ett system som kan användas för att simulera Linux implementeringar av olika TCP versioner och jämföra deras utförande i olika situationer.
Corbel, Romuald. "Évolution des protocoles de transport du point de vue de l'équité." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2019. http://www.theses.fr/2019IMTA0160.
This thesis is in the context of measuring congestion on the network and the evolution of transport protocols. Changes are continually being made to meet the needs of users and new services. Congestion is one of the most critical issues because it has an impact on the performance of Internet networks, hence the need for congestion control algorithms to prevent or remove it. Today, no algorithm perfectly meets the expected requirements, and a lot of research is underway. Nevertheless, these new algorithms can affect network fainress since the behaviour of the transport protocol can change radically depending on the congestion control algorithm used in the endpoints. In addition, in recent years, transport protocols have undergone major changes. A recent significant exampleis Quick UDP Internet Connections (QUIC), a protocol introduced by Google, which aims to replace two widely used transport and security protocols, Transmission Control Protocol (TCP) and Transport Layer Security (TLS). QUIC is implemented in user applications (rather than in the operatingsystem kernel). It is designed to be resistant to ossification and therefore more versatile. This makes content providers, such as Google, hegemonic about the data rate of their users. Due to the progressive development of congestion control algorithms and the evolving nature of transport protocols, new challenges arise in fairness management. This is why, in this thesis, we focused on the development of a test platform to measure network fairness based on the flow rate of the different flows. In addition, in order to characterize fairness as perceived by a user, we focused on determining an impartial procedure for assessing fainress during an entire session of a transport flow (called Session Fairness Assessment(SFA) and Weighted Session Fairness Assessment(WSFA)). Based on these elements, we specifically analyzed the fairness of the protocols when TCP and QUIC flows coexist on a fixed and mobile network. In our fairness assessments, weidentified the impact of aspects of QUIC implementation such as: emulating multiple TCP connections, limiting the size of congestion windows and using the hystart option. The results show that these mechanisms have a strong influence on fairness on both fixed and mobile networks. Indeed,a wrong setting of the default parameters of these mechanisms or the activation of the hystart option can affect the performance of transport protocols and therefore fainress. With regard to the evaluation of congestion control algorithms, the results show that the fainress between two different algorithms depends on the network configuration. This conclusion demonstrates that a measurement procedure, such as the one presented in this thesis, is relevant to conducting the fairness assessment. In this thesis we can conclude that the lack of standardization, for example of emulating multiple TCP connections in QUIC, leads us to question more broadly how QUIC’s design philosophy takes fairness into account. In addition, the results obtained on the evaluation of the fainress of congestion control algorithms allow us to question the fainress evaluation of several contributions when it is not tested in enough network configurations
Ramachandran, Shyamal. "Link Adaptation Algorithm and Metric for IEEE Standard 802.16." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/31364.
Master of Science
Afifi, Mohammed Ahmed Melegy Mohammed. "TCP FTAT (Fast Transmit Adaptive Transmission): A New End-To- End Congestion Control Algorithm." Cleveland State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=csu1414689425.
Fares, Rasha H. A. "Performance modelling and analysis of congestion control mechanisms for communication networks with quality of service constraints. An investigation into new methods of controlling congestion and mean delay in communication networks with both short range dependent and long range dependent traffic." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/5435.
Ministry of Higher Education in Egypt and the Egyptian Cultural Centre and Educational Bureau in London
Fares, Rasha Hamed Abdel Moaty. "Performance modelling and analysis of congestion control mechanisms for communication networks with quality of service constraints : an investigation into new methods of controlling congestion and mean delay in communication networks with both short range dependent and long range dependent traffic." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/5435.
Gliksberg, John. "New routing algorithms for heterogeneous exaflopic supercomputers." Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPASG068.
Building efficient supercomputers requires optimising communications, and their exaflopic scale causes an unavoidable risk of relatively frequent failures.For a cluster with given networking capabilities and applications, performance is achieved by providing a good route for every message while minimising resource access conflicts between messages.This thesis focuses on the fat-tree family of networks, for which we define several overarching properties so as to efficiently take into account a realistic superset of this topology, while keeping a significant edge over agnostic methods.Additionally, a partially novel static congestion risk evaluation method is used to compare algorithms.A generic optimisation is presented for some applications on clusters with heterogeneous equipment.The proposed algorithms use distinct approaches to improve centralised static routing by combining computation speed, fault-resilience, and minimal congestion risk
Jourjon, Guillaume Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Towards a versatile transport protocol." Awarded by:University of New South Wales. Electrical Engineering & Telecommunications, 2008. http://handle.unsw.edu.au/1959.4/41480.
Prabhu, Balakrishna J. "Chaînes de Markov et processus de décision markoviens pour le contrôle de congestion et de puissance." Phd thesis, Université de Nice Sophia-Antipolis, 2005. http://tel.archives-ouvertes.fr/tel-00328111.
Almejalli, Khaled A. "Intelligent Real-Time Decision Support Systems for Road Traffic Management. Multi-agent based Fuzzy Neural Networks with a GA learning approach in managing control actions of road traffic centres." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4264.
Girardet, Brunilde. "Trafic aérien : détermination optimale et globale des trajectoires d'avion en présence de vent." Thesis, Toulouse, INSA, 2014. http://www.theses.fr/2014ISAT0027/document.
In the context of the future Air Traffic Management system (ATM), one objective is to reduce the environmental impact of air traffic. With respect to this criterion, the “freeroute” concept, introduced in the mid 1990’s, is well suited to improve over nowadays airspace based ATM. Aircraft will no longer be restricted to fly along airways and may fly along fuel-optimal routes. The objective of this thesis is to introduce a novel pretactical trajectory planning methodology which aims at minimizing airspace congestion while taking into account weather conditions so as to minimize also fuel consumption.The development of the method was divided in two steps. The first step is dedicated to compute a time-optimal route for one aircraft taking into account wind conditions. This optimization is based on an adaptation of the Ordered Upwind Method on the sphere.The second step introduces a hybrid algorithm, based on simulated annealing and on the deterministic algorithm developed in the first step, in order to minimize congestion. Thus the algorithm combines the ability to reach a globally-optimal solution with a local-search procedure that speeds up the convergence
Sun, Bin, and Wipawat Uppatumwichian. "A Study of Factors Which Influence QoD of HTTP Video Streaming Based on Adobe Flash Technology." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2488.
Jourjon, Guillaume. "Toward a versatile transport protocol." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2008. http://tel.archives-ouvertes.fr/tel-00309959.
Richard, Olivier. "Régulation court terme du trafic aérien et optimisation combinatoire : application de la méthode de génération de colonnes." Phd thesis, Grenoble INPG, 2007. http://tel.archives-ouvertes.fr/tel-00580414.
Yao, Chang-Li, and 姚長利. "Performance Comparison of TCP Congestion Control Algorithms." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/32340586056874661133.
國立成功大學
資訊工程研究所
88
In this thesis, we present the evolution of TCP congestion In In this thesis, we present the evolution of TCP congestion control algorithms and discuss the key ideas of each algorithm. The motivations of these modifications are also addressed. According to the strategy of handling the packet loss, TCP algorithms are classified into loss-recovery and loss-avoidance methods. Reno, which is widely used nowadays, and Vegas are simulated first and the unfairness problem for Reno and Vegas coexistence reveals. This problem prevents users from using Vegas which has better performance than Reno. RED router is discussed to release this problem. Some other simulations are conducted to compare the performance of the TCP algorithms after Reno. We state the ranking positions of the algorithms according to the simulation results. Pseudo-Rate, one of loss-avoidance algorithms, achieves the best performance among all the TCP algorithms.
Abrantes, Filipe Lameiro. "Explicit congestion control algorithms for time-varying capacity media." Doctoral thesis, 2008. http://hdl.handle.net/10216/58447.
Araújo, João Taveira. "Implementation and performance evaluation of explicit congestion control algorithms." Master's thesis, 2008. http://hdl.handle.net/10216/58622.
Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 2008
Araújo, João Taveira. "Implementation and performance evaluation of explicit congestion control algorithms." Dissertação, 2008. http://hdl.handle.net/10216/58622.
Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 2008
Abrantes, Filipe Lameiro. "Explicit congestion control algorithms for time-varying capacity media." Tese, 2008. http://hdl.handle.net/10216/58447.
Kayali, Mahmoud. "Interoperability among rate-based congestion control algorithms for ABR service in ATM networks." Thesis, 1997. http://hdl.handle.net/2429/6406.
Jagannathan, S. Ravi. "Black box modelling of congestion control protocols for computer networks." Thesis, 2009. http://handle.uws.edu.au:8081/1959.7/531210.
Sahasrabudhe, Nachiket S. "Joint Congestion Control, Routing And Distributed Link Scheduling In Power Constrained Wireless Mesh Networks." Thesis, 2008. https://etd.iisc.ac.in/handle/2005/798.
Sahasrabudhe, Nachiket S. "Joint Congestion Control, Routing And Distributed Link Scheduling In Power Constrained Wireless Mesh Networks." Thesis, 2008. http://hdl.handle.net/2005/798.
Yesuratnam, G. "Development Of Algorithms For Security Oriented Power System Operation." Thesis, 2007. https://etd.iisc.ac.in/handle/2005/573.
Yesuratnam, G. "Development Of Algorithms For Security Oriented Power System Operation." Thesis, 2007. http://hdl.handle.net/2005/573.
Lin, Tien-Huamr, and 林添華. "A Group-based Congestion Control Algorithm for Active Queue Management." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/06685523336186578602.
國立中興大學
資訊科學系所
94
In a congested network, an aggressive node could acquire more bandwidth for itself by intentionally increasing the number of flows. This leads to a serious problem of fairness in bandwidth allocation. This problem can be solved by a technique known as virtual queue. In the network, each node employs a virtual queue with an initial drop probability. The probability is dynamically adjusted for each node to acquire a fair share of the bandwidth. However, the virtual-queue technique has a major drawback, it bccomes considerably difficult and impractical to manage a large number of virtual queues, as the number of nodes explodes. In this thesis, we propose an efficient method to deal with this problem. Our idea is to sort nodes into groups on the basis of flow numbers. Nodes with similar flow numbers are placed in a group and they share a single virtual queue for bandwidth allocation. We verify the effectiveness of our proposed method through a simulation tool – ns2. By calculating fairness index, we are able to evaluate the performance of our method operating in various conditions. The simulation results show that the proposed method can effectively reduce the number of virtual queues in use. In addition, it guarantees that all the nodes receive a fair treatment of bandwidth allocation.
Lin, Wei-Chung, and 林偉正. "An Improved Random Early Detection (RED) Algorithm for Congestion Control." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/16896950377494718155.
國立中興大學
資訊科學系所
95
Many proposals have been adopted in controlling the congestions in the routers, including Random Early Detection (RED) and Drop-tail, and have shown to improve the loss rate, throughput, fairness, etc. of the network. Although RED algorithm is designed for TCP for a active queue management, we found that when comes to dropping the packets, it treats packets equally, ignoring the effect of the the size of the packets. This results in higher loss rate of packets and lower throughput for smaller packets. In this thesis, we propose to improve the original RED algorithm by differentiating packet sizes and devise RED_average algorithm and further improved PS_average algorithm. We then use ns-2 to simulate the performance of the aforementioned three algorithm.based on three MTU sizes. The results showed that if we take the factor of the packet size into consideration, the RED_average algorithm has a better loss rate and throughput. The PS_average, which takes the average packet size into consideration to adjust the intended loss rate for smaller packates, has a even further improved performance. We have shown that by the above two new algorithms, a better balance for the loss rate for all packets can be achieved, and thus improved utilization of the network resources.
Ryu, Jung Ho. "Congestion control and routing over challenged networks." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-12-4620.
text
Vallamsundar, Banupriya. "Congestion Control for Adaptive Satellite Communication Systems with Intelligent Systems." Thesis, 2007. http://hdl.handle.net/10012/3295.
Ho, Cheng-Yuan, and 何承遠. "Design and Performance Evaluation of an End-to-end Congestion Control Algorithm." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/78906900024523365472.
國立交通大學
資訊科學與工程研究所
96
The success of the Internet can be attributed to the large number of useful applications which are easily executed by a user for running on the Internet. Transmission Control Protocol (TCP) is a widely deployed end-to-end transport protocol in the current Internet. This is because TCP provides an acceptable service with a reliable data transport as well as controls the connection's bandwidth usage to avoid network congestion for two end hosts in the Internet. Nowadays, the research of TCP/IP is still a hot topic in both the academia and the industry. With the fast growth of Internet hardware, technologies, and applications, the network bandwidth of a user is getting higher and wireless links are more and more popular everywhere. This will make Internet traffic increase quickly and the ways of data transport vary. Also, users' demands for network performance are getting stricter. Facing these challenges, how to efficiently utilize network resources, how to work well in both high bandwidth network and heterogeneous network (mixed with wired and wireless networks), and how to satisfy users' requests are essential issues to a successful congestion control mechanism. In addition, if the modification of TCP's congestion control does not catch up the Internet change, the performance bottleneck will soon be TCP itself. Up to now, in order to improve network utilization, TCP has several implementation versions which can be classified into two categories, loss-based TCPs and delay-based TCPs. Although it has been demonstrated that the delay-based TCP outperforms the loss-based TCP in the aspects of overall network utilization, stability, fairness, throughput, etc., in the real Internet, loss-based TCPs are still the mainstream and remained as the dominant algorithm used in practice. Furthermore, the implementation of a loss-based TCP is easier than that of a delay-based TCP, and a loss-based TCP could get more resources than a delay-based TCP could when they coexist in the same network, so many studies focus on loss-based TCP algorithms, and one version of loss-based TCP mechanisms, TCP SACK, has been widely deployed on the Internet. However, in fact, loss-based and delay-based TCPs have their own advantages and shortcomings. Hence, there is an issue ``how do we design the algorithm and architecture of TCP?'' In this dissertation, we propose a novel end-to-end congestion control mechanism called Medley TCP that is able to efficiently utilize Internet resources, adapt itself to a new network circumstance, satisfy users' requests, and accommodate shortcomings of the conventional TCP. Medley TCP differs from the traditional TCP extremely in that we redesign the algorithm and architecture of the whole congestion control mechanism of TCP. Specifically, Medley TCP tries to combine advantages and characteristics of both loss-based and delay-based TCPs, and therefore incorporates a scalable delay-based component into a loss-based TCP algorithm. This scalable delay-based component has a rapid window increase rule when the network is sensed to be under-utilized and gracefully reduces the sending rate once the bottleneck queue is built. Therefore, Medley TCP connections will react faster and better to high BDP networks and improve the overall performance. Moreover, we utilize the innate nature of Medley TCP to detect congestion losses or random packet losses precisely. Through the packet loss differentiation, Medley TCP reacts appropriately to the losses and consequently the throughput of connection over heterogeneous networks can be significantly improved. Extensive experiments of a network simulator and real world Internet traffic measurements have been conducted and show that Medley TCP not only can improve the performance significantly over high BDP networks and heterogeneous networks but also can keep the good characteristics of delay-based TCPs in the aspects of overall network utilization, stability, fairness, throughput, and so on. Importantly, Medley TCP does not cause any detrimental effects to TCP SACK, and vice versa when they share same resources in the networks: that is, Medley TCP connections achieve higher throughput by using bandwidth that will not be used by SACK connections anyway, not ``stealing'' bandwidth from SACK's connections. Finally, Medley TCP only involves modification at the sender without requiring changes of the receiver protocol stack or intermediate router nodes. As a result, it can be easily deployed in the current Internet.
Chiu, Kuo-Tung, and 邱國棟. "Performance Analysis of congestion control Algorithm for the Medium Access controller of 802.11 WLANs." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/91268554109053285725.
中華大學
電機工程學系(所)
98
Abstract This dissertation is proposing an improved mechanism to better eliminate the predicament of network congestion occurs in Wireless LAN (WLAN). As the number of workstations in a crowded network increases, the probabilities of collision increase as well. From the IEEE 802.11 DCF algorithm, queuing of station transmission is scheduled based on the CSMA/CA and Binary Exponential Back-off scheme. Although Back-off reduce number of collisions in the network, its effectiveness is restrained because each individual workstation is unaware of the current network congest state and places transmitting data onto the channel indiscriminately, which causes a higher collision probabilities. According to the paper, a Distributed Contention Control (DCC) method is suggested to correct the problem with collision avoidance in the IEEE 802.11 DCF system. Before a workstation transmits, DCC mechanism evaluates the current Slot usage rate. A low Slot usage rate corresponds to an intense channel contention. To avoid collision, DCC would Defer Access to the transmission channel for a period of time and rearrange the transmission moment for the workstations. Even though this method is capable of decreasing collision possibility and thus alleviating congestion, it causes an unstable condition in channel access for the workstations. This is due to that DCC can only detect the “presence” of data transmission. A DCC system would generate unnecessary waiting by stalling transmission even if a merely small number of workstations exist. Take this concern into consideration, a mechanism as an improvement to the DCC scheme is proposed in our paper, the Modifier DCC (M-DCC) method. We narrow the requirement to include the condition, “when multiple workstations are competing for access,” so that only when this condition is true, will access be deferred. In addition, a Markov Chain mathematical model is used to analyze and compare between DCF, DCC, and the M-DCC method. Through MATLAB evaluation, it is verified that the M-DCC method can not only enhance DCC efficiency, effectively diminish congestion level, reduce the collision probabilities, but also boost data throughput.
Wang, Wun-jhang, and 汪汶樟. "Study on TCP Congestion Window Control Algorithm to Improve TCP Performance in Heterogeneous Networks." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/32432290741941024673.
大葉大學
資訊工程學系碩士班
99
Recently, the TCP performance in the heterogeneous network has become a focus of the study. In traditional wired networks, the transmission error rate is very low. Therefore, the packet loss resulting in the transmission performance degradation is due to the network congestion. However, the Internet today is no longer just connected with the wired networks. Both the wired and wireless links may exist in a TCP connection. In wireless links due to interference or noise of the wireless transmission channel, the bit error rate (BER) is much higher than the wired links. The higher BER results in the increase of the packet loss. If the TCP algorithm still assumes the packet loss is due to the network congestion and reduces the congestion windows, the performance of TCP connection will be serious degradation. Therefore, this thesis proposed an algorithm to detect the network congestion and BER. The proposed algorithm records the TCP packet sending time and the corresponding ACK packet received time to calculate a parameter which is defined as the RTT ratio. With the RTT ratio, the proposed algorithm determines the reason of packet loss, and adjust the TCP congestion window and slow start threshold according to the determination. The NS2 simulation results show that the proposed algorithm performs much better than the TCP Reno in a high BER environment at the cost of little degradation of performance in a small BER environment. Key Words:TCP Reno, Congestion control, Congestion Windows, RTT
Lierkamp, Darren University of Ballarat. "A New ramp metering control algorithm for optimizing freeway travel times." 2006. http://archimedes.ballarat.edu.au:8080/vital/access/HandleResolver/1959.17/12726.
Masters of Information Technology
Lierkamp, Darren. "A new ramp metering control algorithm for optimizing freeway travel times." Thesis, 2006. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/63788.
Masters of Information Technology
Lierkamp, Darren. "A New ramp metering control algorithm for optimizing freeway travel times." 2006. http://archimedes.ballarat.edu.au:8080/vital/access/HandleResolver/1959.17/14605.
Masters of Information Technology
張康維. "A distributed/parallel algorithm for the optimal congestion control of a single destination data network." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/14997934354440983409.