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Phirke, Vishal Vasudeo. "Traffic Sensitive Active Queue Management for Improved Quality of Service." Digital WPI, 2002. https://digitalcommons.wpi.edu/etd-theses/780.
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The Internet, traditionally FTP, e-mail and Web traffic, is increasingly supporting emerging applications such as IP telephony, video conferencing and online games. These new genres of applications have different requirements in terms of throughput and delay than traditional applications. For example, interactive multimedia applications, unlike traditional applications, have more stringent delay constraints and less stringent loss constraints. Unfortunately, the current Internet offers a monolithic best-effort service to all applications without considering their specific requirements. Adaptive RED (ARED) is an Active Queue Management (AQM) technique, which optimizes the router for throughput. Throughput optimization provides acceptable QoS for traditional throughput sensitive applications, but is unfair for these new delay sensitive applications. While previous work has used different classes of QoS at the router to accommodate applications with varying requirements, thus far all have provided just 2 or 3 classes of service for applications to choose from. We propose two AQM mechanisms to optimize router for better overall QoS. Our first mechanism, RED-Worcester, is a simple extension to ARED in order to tune ARED for better average QoS support. Our second mechanism, REDBoston, further extends RED-Worcester to improve the QoS for all flows. Unlike earlier approaches, we do not predefine classes of service, but instead provide a continuum from which applications can choose. We evaluate our approach using NS-2 and present results showing the amount of improvement in QoS achieved by our mechanisms over ARED.
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Mohamed, Mahmud H. Etbega. "Some Active Queue Management Methods for Controlling Packet Queueing Delay. Design and Performance Evaluation of Some New Versions of Active Queue Management Schemes for Controlling Packet Queueing Delay in a Buffer to Satisfy Quality of Service Requirements for Real-time Multimedia Applications." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/4258.
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Traditionally the Internet is used for the following applications: FTP, e-mail and Web traffic. However in the recent years the Internet is increasingly supporting emerging applications such as IP telephony, video conferencing and online games. These new applications have different requirements in terms of throughput and delay than traditional applications. For example, interactive multimedia applications, unlike traditional applications, have more strict delay constraints and less strict loss constraints. Unfortunately, the current Internet offers only a best-effort service to all applications without any consideration to the applications specific requirements. In this thesis three existing Active Queue Management (AQM) mechanisms are modified by incorporating into these a control function to condition routers for better Quality of Service (QoS). Specifically, delay is considered as the key QoS metric as it is the most important metric for real-time multimedia applications. The first modified mechanism is Drop Tail (DT), which is a simple mechanism in comparison with most AQM schemes. A dynamic threshold has been added to DT in order to maintain packet queueing delay at a specified value. The modified mechanism is referred to as Adaptive Drop Tail (ADT). The second mechanism considered is Early Random Drop (ERD) and, iii in a similar way to ADT, a dynamic threshold has been used to keep the delay at a required value, the main difference being that packets are now dropped probabilistically before the queue reaches full capacity. This mechanism is referred to as Adaptive Early Random Drop (AERD). The final mechanism considered is motivated by the well known Random Early Detection AQM mechanism and is effectively a multi-threshold version of AERD in which packets are dropped with a linear function between the two thresholds and the second threshold is moveable in order to change the slope of the dropping function. This mechanism is called Multi Threshold Adaptive Early Random Drop (MTAERD) and is used in a similar way to the other mechanisms to maintain delay around a specified level. The main focus with all the mechanisms is on queueing delay, which is a significant component of end-to-end delay, and also on reducing the jitter (delay variation) A control algorithm is developed using an analytical model that specifies the delay as a function of the queue threshold position and this function has been used in a simulation to adjust the threshold to an effective value to maintain the delay around a specified value as the packet arrival rate changes over time. iv A two state Markov Modulated Poisson Process is used as the arrival process to each of the three systems to introduce burstiness and correlation of the packet inter-arrival times and to present sudden changes in the arrival process as might be encountered when TCP is used as the transport protocol and step changes the size of its congestion window. In the investigations it is assumed the traffic source is a mixture of TCP and UDP traffic and that the mechanisms conserved apply to the TCP based data. It is also assumed that this consists of the majority proportion of the total traffic so that the control mechanisms have a significant effect on controlling the overall delay. The three mechanisms are evaluated using a Java framework and results are presented showing the amount of improvement in QoS that can be achieved by the mechanisms over their non-adaptive counterparts. The mechanisms are also compared with each other and conclusions drawn.
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Li, 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/.
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Improving network performance in terms of efficiency, fairness in the bandwidth, and system stability has been a research issue for decades. Current Internet traffic control maintains sophistication in end TCPs but simplicity in routers. In each router, incoming packets queue up in a buffer for transmission until the buffer is full, and then the packets are dropped. This router queue management strategy is referred to as Drop Tail. End TCPs eventually detect packet losses and slow down their sending rates to ease congestion in the network. This way, the aggregate sending rate converges to the network capacity. In the past, Drop Tail has been adopted in most routers in the Internet due to its simplicity of implementation and practicability with light traffic loads. However Drop Tail, with heavy-loaded traffic, causes not only high loss rate and low network throughput, but also long packet delay and lengthy congestion conditions. To address these problems, active queue management (AQM) has been proposed with the idea of proactively and selectively dropping packets before an output buffer is full. The essence of AQM is to drop packets in such a way that the congestion avoidance strategy of TCP works most effectively. Significant efforts in developing AQM have been made since random early detection (RED), the first prominent AQM other than Drop Tail, was introduced in 1993. Although various AQMs also tend to improve fairness in bandwidth among flows, the vulnerability of short-lived flows persists due to the conservative nature of TCP. It has been revealed that short-lived flows take up traffic with a relatively small percentage of bytes but in a large number of flows. From the user’s point of view, there is an expectation of timely delivery of short-lived flows. Our approach is to apply artificial intelligence technologies, particularly fuzzy logic (FL), to address these two issues: an effective AQM scheme, and preferential treatment for short-lived flows. Inspired by the success of FL in the robust control of nonlinear complex systems, our hypothesis is that the Internet is one of the most complex systems and FL can be applied to it. First of all, state of the art AQM schemes outperform Drop Tail, but their performance is not consistent under different network scenarios. Research reveals that this inconsistency is due to the selection of congestion indicators. Most existing AQM schemes are reliant on queue length, input rate, and extreme events occurring in the routers, such as a full queue and an empty queue. This drawback might be overcome by introducing an indicator which takes account of not only input traffic but also queue occupancy for early congestion notification. The congestion indicator chosen in this research is traffic load factor. Traffic load factor is in fact dimensionless and thus independent of link capacity, and also it is easy to use in more complex networks where different traffic classes coexist. The traffic load indicator is a descriptive measure of the complex communication network, and is well suited for use in FL control theory. Based on the traffic load indicator, AQM using FL – or FLAQM – is explored and two FLAQM algorithms are proposed. Secondly, a mice and elephants (ME) strategy is proposed for addressing the problem of the vulnerability of short-lived flows. The idea behind ME is to treat short-lived flows preferably over bulk flows. ME’s operational location is chosen at user premise gateways, where surplus processing resources are available compared to other places. By giving absolute priority to short-lived flows, both short and long-lived flows can benefit. One problem with ME is starvation of elephants or long-lived flows. This issue is addressed by dynamically adjusting the threshold distinguishing between mice and elephants with the guarantee that minimum capacity is maintained for elephants. The method used to dynamically adjust the threshold is to apply FL. FLAQM is deployed to control the elephant queue with consideration of capacity usage of mice packets. In addition, flow states in a ME router are periodically updated to maintain the data storage. The application of the traffic load factor for early congestion notification and the ME strategy have been evaluated via extensive experimental simulations with a range of traffic load conditions. The results show that the proposed two FLAQM algorithms outperform some well-known AQM schemes in all the investigated network circumstances in terms of both user-centric measures and network-centric measures. The ME strategy, with the use of FLAQM to control long-lived flow queues, improves not only the performance of short-lived flows but also the overall performance of the network without disadvantaging long-lived flows.
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Al-Hammouri, Ahmad Tawfiq. "INTERNET CONGESTION CONTROL: COMPLETE STABILITY REGION FOR PI AQM AND BANDWIDTH ALLOCATION IN NETWORKED CONTROL." online version, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1189088621.
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Wang, Lan. "Performance modeling of congestion control and resource allocation under heterogeneous network traffic : modeling and analysis of active queue management mechanism in the presence of poisson and bursty traffic arrival processes." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4455.
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Along with playing an ever-increasing role in the integration of other communication networks and expanding in application diversities, the current Internet suffers from serious overuse and congestion bottlenecks. Efficient congestion control is fundamental to ensure the Internet reliability, satisfy the specified Quality-of-Service (QoS) constraints and achieve desirable performance in response to varying application scenarios. Active Queue Management (AQM) is a promising scheme to support end-to-end Transmission Control Protocol (TCP) congestion control because it enables the sender to react appropriately to the real network situation. Analytical performance models are powerful tools which can be adopted to investigate optimal setting of AQM parameters. Among the existing research efforts in this field, however, there is a current lack of analytical models that can be viewed as a cost-effective performance evaluation tool for AQM in the presence of heterogeneous traffic, generated by various network applications. This thesis aims to provide a generic and extensible analytical framework for analyzing AQM congestion control for various traffic types, such as non-bursty Poisson and bursty Markov-Modulated Poisson Process (MMPP) traffic. Specifically, the Markov analytical models are developed for AQM congestion control scheme coupled with queue thresholds and then are adopted to derive expressions for important QoS metrics. The main contributions of this thesis are listed as follows: • Study the queueing systems for modeling AQM scheme subject to single-class and multiple-classes Poisson traffic, respectively. Analyze the effects of the varying threshold, mean traffic arrival rate, service rate and buffer capacity on the key performance metrics. • Propose an analytical model for AQM scheme with single class bursty traffic and investigate how burstiness and correlations affect the performance metrics. The analytical results reveal that high burstiness and correlation can result in significant degradation of AQM performance, such as increased queueing delay and packet loss probability, and reduced throughput and utlization. • Develop an analytical model for a single server queueing system with AQM in the presence of heterogeneous traffic and evaluate the aggregate and marginal performance subject to different threshold values, burstiness degree and correlation. • Conduct stochastic analysis of a single-server system with single-queue and multiple-queues, respectively, for AQM scheme in the presence of multiple priority traffic classes scheduled by the Priority Resume (PR) policy. • Carry out the performance comparison of AQM with PR and First-In First-Out (FIFO) scheme and compare the performance of AQM with single PR priority queue and multiple priority queues, respectively.
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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.
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Active Queue Management (AQM) schemes are used for ensuring the Quality of Service (QoS) in telecommunication networks. However, they are sensitive to parameter settings and have weaknesses in detecting and controlling congestion under dynamically changing network situations. Another drawback for the AQM algorithms is that they have been applied only on the Markovian models which are considered as Short Range Dependent (SRD) traffic models. However, traffic measurements from communication networks have shown that network traffic can exhibit self-similar as well as Long Range Dependent (LRD) properties. Therefore, it is important to design new algorithms not only to control congestion but also to have the ability to predict the onset of congestion within a network.
An aim of this research is to devise some new congestion control methods for communication networks that make use of various traffic characteristics, such as LRD, which has not previously been employed in congestion control methods currently used in the Internet. A queueing model with a number of ON/OFF sources has been used and this incorporates a novel congestion prediction algorithm for AQM. The simulation results have shown that applying the algorithm can provide better performance than an equivalent system without the prediction. Modifying the algorithm by the inclusion of a sliding window mechanism has been shown to further improve the performance in terms of controlling the total number of packets within the system and improving the throughput.
Also considered is the important problem of maintaining QoS constraints, such as mean delay, which is crucially important in providing satisfactory transmission of real-time services over multi-service networks like the Internet and which were not originally designed for this purpose. An algorithm has been developed to provide a control strategy that operates on a buffer which incorporates a moveable threshold. The algorithm has been developed to control the mean delay by dynamically adjusting the threshold, which, in turn, controls the effective arrival rate by randomly dropping packets. This work has been carried out using a mixture of computer simulation and analytical modelling. The performance of the new methods that haveMinistry of Higher Education in Egypt and the Egyptian Cultural Centre and Educational Bureau in London
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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.
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Active Queue Management (AQM) schemes are used for ensuring the Quality of Service (QoS) in telecommunication networks. However, they are sensitive to parameter settings and have weaknesses in detecting and controlling congestion under dynamically changing network situations. Another drawback for the AQM algorithms is that they have been applied only on the Markovian models which are considered as Short Range Dependent (SRD) traffic models. However, traffic measurements from communication networks have shown that network traffic can exhibit self-similar as well as Long Range Dependent (LRD) properties. Therefore, it is important to design new algorithms not only to control congestion but also to have the ability to predict the onset of congestion within a network. An aim of this research is to devise some new congestion control methods for communication networks that make use of various traffic characteristics, such as LRD, which has not previously been employed in congestion control methods currently used in the Internet. A queueing model with a number of ON/OFF sources has been used and this incorporates a novel congestion prediction algorithm for AQM. The simulation results have shown that applying the algorithm can provide better performance than an equivalent system without the prediction. Modifying the algorithm by the inclusion of a sliding window mechanism has been shown to further improve the performance in terms of controlling the total number of packets within the system and improving the throughput. Also considered is the important problem of maintaining QoS constraints, such as mean delay, which is crucially important in providing satisfactory transmission of real-time services over multi-service networks like the Internet and which were not originally designed for this purpose. An algorithm has been developed to provide a control strategy that operates on a buffer which incorporates a moveable threshold. The algorithm has been developed to control the mean delay by dynamically adjusting the threshold, which, in turn, controls the effective arrival rate by randomly dropping packets. This work has been carried out using a mixture of computer simulation and analytical modelling. The performance of the new methods that have.
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Chung, Jae Won. "Congestion control for streaming media." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-081805-084831/.
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Dissertation (Ph.D.) -- Worcester Polytechnic Institute.Keywords: streaming media; streaming transport protocol; active queue management (AQM); Internet congestion control. Includes bibliographical references (p. 236-248).
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Nikaeen, Ramin. "Combined Queue-Rate Active Queue Management for Internet congestion control." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63024.pdf.
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Dahlberg, Love. "A Data Plane native PPV PIE Active Queue Mangement Scheme using P4 on a Programmable Switching ASIC." Thesis, Karlstads universitet, Institutionen för matematik och datavetenskap (from 2013), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-84552.
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New internet services require low and stable latency, which is difficult to provide with traditional routers and queuing mechanisms. Current routers aim to provide high throughput using large buffers causing considerable network latency under load. Recently, Active Queue Management (AQM) algorithms have been proposed to reduce such problem by actively controlling queue lengths to maintain target latencies. However, AQMs are difficult to implement in switching Application-Specific Integrated Circuits (ASIC) due to inherent architectural constraints. On the other hand, resource sharing is another important goal aiming to differentiate traffic and allocating more resources to different traffic types. The objective of this thesis is to implement the AQM algorithm Proportional Integral Controller Enhanced (PIE) with a packet marking based resource sharing concept Per Packet Value (PPV) on a programmable switching ASIC using the novel network programmability concept P4. Our solution is designed to maintain low and controllable latency and to utilize the bottleneck link efficiently, while observing the bandwidth sharing properties of the marking scheme. Our goal is to show that Data Plane native implementations of PPV PIE using the Tofino is possible without severely limiting performance or accuracy. The solution places the computation of PIE's drop probability estimation on a timer in the Data Plane utilizing a state machine, packet mirroring, packet recirculation and approximative arithmetics implemented by lookup tables. Additionally, a small control loop is required in order to update lookup tables based on packet statistics from the Control Plane. In our evaluation using a Tofino based testbed, we evaluate the impact of different parameters on both Control Plane latency, Data Plane throughput and delay for both static and dynamic traffic scenarios. Our results demonstrate commendable performance in terms of controlling queuing delay, effective throughput and bandwidth share when taking operator policy in regard.
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Santi, Juliana de 1982. "Gerenciamento ativo de filas para o protocolo "High Speed Transmission Control Protocol" em redes com produto banda-atraso elevado." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276151.
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Orientador: Nelson Luis Saldanha da FonsecaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação
Made available in DSpace on 2018-08-13T10:35:13Z (GMT). No. of bitstreams: 1 Santi_Julianade_M.pdf: 1658984 bytes, checksum: 8a9f078587406a06815484e4fe057f7d (MD5) Previous issue date: 2008
Resumo: A utilização eficiente da banda passante em redes de alta velocidade e grandes atrasos, denominadas redes com produto banda-atraso elevado (PBA), tornou-se um grande desafio. Isto ocorre devido aos ajustes do protocolo Transmission Control Protocol (TCP). O High Speed TCP (HSTCP), uma variante do TCP para redes com PBA elevado, emprega ajustes mais agressivos permitindo, assim, que a utilização da banda seja escalável. As políticas de Gerenciamento Ativo de Filas ou Active Queue Management (AQM), monitoram o nível de ocupação das filas nos roteadores e notificam o congestionamento incipiente aos emissores TCP através do descarte/marcação de pacotes. O sistema de controle de congestionamento apresenta natureza de retroalimentação, na qual a taxa de transmissão dos nós fontes é ajustada em função do nível de ocupação da fila. Os controladores AQM determinam a probabilidade de descarte/marcação para maximizar a vazão e minimizar perdas, garantindo, assim, a estabilidade do tamanho da fila independentemente das variações das condições da rede. Neste trabalho, define-se a política de gerenciamento ativo de filas HSTCP-H2 para redes com PBA elevado que utilizam o protocolo HSTCP. Para a derivação de HSTCPH2: são utilizadas técnicas de Teoria de Controle Ótimo. A principal característica desta política é considerar o atraso do sistema o que permite melhor utilização dos recursos disponíveis. A estabilidade e os objetivos de desempenho do sistema são expressos e solucionados através de Desigualdades Matriciais Lineares, permitindo que os parâmetros do controlador possam ser calculados através da solução de um problema convexo simples. Diferentes controladores foram derivados considerando-se diferentes objetivos de desempenho, os quais consideram as características de redes com produto banda-atraso elevado. Através de simulações, os desempenhos dos controladores derivados são avaliados e a eficácia do controlador que apresentou o melhor desempenho foi comparado com o desempenho da política de AQM RED. São considerados cenários com enlace gargalo único e com múltiplos gargalos.
Abstract: The efficient utilization of bandwidth in high speed and large delay networks, called high bandwidth-delay product networks (BDP), has become a major challenge. This is due to adjustments of the Transmission Control Protocol (TCP). The High Speed TCP HSTCP): a TCP variant to high BDP networks, employs more aggressive adjustments, allowing scalable bandwidth utilization. The Active Queue Management (AQM) policies monitor the queue length in the routers and notify incipient congestion to TCP source by marking or dropping packets. The congestion control system presents intrinsic feedback nature, where the transmission rates of the sources are adjusted according to the level of congestion inferred by the queue occupancy. The AQM controllers determine the dropping marking probability values to maximize throughput and minimize losses, giving guarantees to stabilize the queue length independent of network conditions. In this work, it is defined HSTCP-H2, an active queue management policy to high BDP networks, which adopt the HSTCP as their transport protocol. Optimal control theory is used to conceive HSTCP-H2. The novelty of the proposed approach lies in consider the delay of the system which allows better use of available resources. Furthermore, in the proposed approach, stability and performance objectives are completely expressed as Linear Matrix Inequalities (LMIs), thus requiring the solution of a single convex problem for the computation of the controller parameters. Different controllers are derived considering different design goals, which take into account the characteristics of the high bandwidth-delay product networks. The performance produced by different optimal controllers was investigated. The efficacy of the controller with the best performance was then compared to the performance of RED policy. The simulation experiments were carried out using topologies with single and multiple bottleneck.
Mestrado
Redes de Computadores
Mestre em Ciência da Computação
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Adams, Richelle Vive-Anne. "Infinitesimal Perturbation Analysis for Active Queue Management." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19844.
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Active queue management (AQM) techniques for congestion control in Internet Protocol (IP) networks have been designed using both heuristic and analytical methods. But so far, there has been found no AQM scheme designed in the realm of stochastic optimization. Of the many options available in this arena, the gradient-based stochastic approximation method using Infintesimal Perturbation Analysis (IPA) gradient estimators within the Stochastic Fluid Model (SFM) framework is very promising. The research outlined in this thesis provides the theoretical basis and foundational layer for the development of IPA-based AQM schemes. Algorithms for computing the IPA gradient estimators for loss volume and queue workload were derived for the following cases: a single-stage queue with instantaneous, additive loss-feedback, a single-stage queue with instantaneous, additive loss-feedback and an unresponsive competing flow, a single-stage queue with delayed, additive loss-feedback, and a multi-stage tandem network of $m$ queues with instantaneous, additive loss-feedback. For all cases, the IPA gradient estimators were derived with the control parameter, $ heta$, being the buffer-limits of the queue(s). For the single-stage case and the multi-stage case with instantaneous, additive loss-feedback, the IPA gradient estimators for when the control parameter, $ heta$, is the loss-feedback constant, were also derived. Sensitivity analyses and optimizations were performed with control parameter, $ heta$, being the buffer-limits of the queue(s), as well as the loss-feedback constant.
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Jou, Jia-Shiang. "Multifractal internet traffic model and active queue management." College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/53.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2003.Thesis research directed by: Electrical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Wang, Xiaoyan. "Active queue management for real-time IP traffic." Thesis, Queen Mary, University of London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444160.
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Chan, Ming Kit. "Active queue management schemes using a capture-recapture model /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?COMP%202002%20CHAN.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 58-61). Also available in electronic version. Access restricted to campus users.
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Yu, Bo. "Delay-oriented active queue management in TCP/IP networks." Thesis, Queen Mary, University of London, 2011. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1331.
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Internet-based applications and services are pervading everyday life. Moreover, the growing popularity of real-time, time-critical and mission-critical applications set new challenges to the Internet community. The requirement for reducing response time, and therefore latency control is increasingly emphasized. This thesis seeks to reduce queueing delay through active queue management. While mathematical studies and research simulations reveal that complex trade-off relationships exist among performance indices such as throughput, packet loss ratio and delay, etc., this thesis intends to find an improved active queue management algorithm which emphasizes delay control without trading much on other performance indices such as throughput and packet loss ratio. The thesis observes that in TCP/IP network, packet loss ratio is a major reflection of congestion severity or load. With a properly functioning active queue management algorithm, traffic load will in general push the feedback system to an equilibrium point in terms of packet loss ratio and throughput. On the other hand, queue length is a determinant factor on system delay performance while has only a slight influence on the equilibrium. This observation suggests the possibility of reducing delay while maintaining throughput and packet loss ratio relatively unchanged. The thesis also observes that queue length fluctuation is a reflection of both load changes and natural fluctuation in arriving bit rate. Monitoring queue length fluctuation alone cannot distinguish the difference and identify congestion status; and yet identifying this difference is crucial in finding out situations where average queue size and hence queueing delay can be properly controlled and reasonably reduced. However, many existing active queue management algorithms only monitor queue length, and their control policies are solely based on this measurement. In our studies, our novel finding is that the arriving bit rate distribution of all sources contains information which can be a better indication of congestion status and has a correlation with traffic burstiness. And this thesis develops a simple and scalable way to measure its two most important characteristics, namely the mean ii and the variance of the arriving rate distribution. The measuring mechanism is based on a Zombie List mechanism originally proposed and deployed in Stabilized RED to estimate the number of flows and identify misbehaving flows. This thesis modifies the original zombie list measuring mechanism, makes it capable of measuring additional variables. Based on these additional measurements, this thesis proposes a novel modification to the RED algorithm. It utilizes a robust adaptive mechanism to ensure that the system reaches proper equilibrium operating points in terms of packet loss ratio and queueing delay under various loads. Furthermore, it identifies different congestion status where traffic is less bursty and adapts RED parameters in order to reduce average queue size and hence queueing delay accordingly. Using ns-2 simulation platform, this thesis runs simulations of a single bottleneck link scenario which represents an important and popular application scenario such as home access network or SoHo. Simulation results indicate that there are complex trade-off relationships among throughput, packet loss ratio and delay; and in these relationships delay can be substantially reduced whereas trade-offs on throughput and packet loss ratio are negligible. Simulation results show that our proposed active queue management algorithm can identify circumstances where traffic is less bursty and actively reduce queueing delay with hardly noticeable sacrifice on throughput and packet loss ratio performances. In conclusion, our novel approach enables the application of adaptive techniques to more RED parameters including those affecting queue occupancy and hence queueing delay. The new modification to RED algorithm is a scalable approach and does not introduce additional protocol overhead. In general it brings the benefit of substantially reduced delay at the cost of limited processing overhead and negligible degradation in throughput and packet loss ratio. However, our new algorithm is only tested on responsive flows and a single bottleneck scenario. Its effectiveness on a combination of responsive and non-responsive flows as well as in more complicated network topology scenarios is left for future work.
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Giglio, Alberto. "Router-based Congestion Control through Control Theoretic Active Queue Management." Thesis, KTH, Reglerteknik, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109475.
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Fountanas, Leonidas. "Active queue management mechanisms for real-time traffic in MANETs /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA401102.
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Thesis (Electrical Engineer and M.S. in Electrical Engineering) Naval Postgraduate School, Dec. 2001."December 2001." Thesis advisor(s): Tummala, Murali ; Ives, Robert W. ; Parker, Robert E. Includes bibliographical references (p. 101-104). Also available online.
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Fountanas, Leonidas, and Leonidas Fountanas. "Active queue management mechanisms for real-time traffic in MANETs." Thesis, Monterey, California. Naval Postgraduate School, 2001. http://hdl.handle.net/10945/6052.
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Approved for public release; distribution is unlimited.Approved for public release; distribution is unlimited.
This thesis develops active queue management mechanisms for real-time traffic for MANETs. Providing QoS for real-time applications is still an open issue as stated in RFC 2309. The proposed packet-dropping algorithm called Selective Early Discard (SED) selectively drops packets in order to spread the packet losses in a queue. Two variations of SED are also examined: one adds priority in order to provide service differentiation and the other utilizes timestamps to enable the intermediate nodes to drop packets that are likely to be unusable by the receiver due to excessive delay. Another scheme that drops bits instead of packets is also investigated. Using simulation, the new queuing schemes are evaluated in a MANET environment, and their performance is compared with other existing QoS schemes, such as Random Early Discard (RED) and First In First Out (FIFO). Results indicate that SED minimizes the burst errors due to buffer overflow, thereby improving the performance for real-time traffic. SED is also capable of providing service differentiation; additional performance improvement can be realized by utilizing timestamps. Bit-dropping techniques can provide further performance improvements by spreading the error at the bit level (versus spreading the error at the packet level as in SED).
This thesis develops active queue management mechanisms for real-time traffic for MANETs. Providing QoS for real-time applications is still an open issue as stated in RFC 2309. The proposed packet-dropping algorithm called Selective Early Discard (SED) selectively drops packets in order to spread the packet losses in a queue. Two variations of SED are also examined: one adds priority in order to provide service differentiation and the other utilizes timestamps to enable the intermediate nodes to drop packets that are likely to be unusable by the receiver due to excessive delay. Another scheme that drops bits instead of packets is also investigated. Using simulation, the new queuing schemes are evaluated in a MANET environment, and their performance is compared with other existing QoS schemes, such as Random Early Discard (RED) and First In First Out (FIFO). Results indicate that SED minimizes the burst errors due to buffer overflow, thereby improving the performance for real-time traffic. SED is also capable of providing service differentiation; additional performance improvement can be realized by utilizing timestamps. Bit-dropping techniques can provide further performance improvements by spreading the error at the bit level (versus spreading the error at the packet level as in SED).
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Lie, Arne. "Enhancing Rate Adaptive IP Streaming Media Performance with the use of Active Queue Management." Doctoral thesis, Norwegian University of Science and Technology, Department of Telematics, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2092.
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The Internet is today a world wide packet switching arena constituting enormous possibilities of new services and business creation. E.g., there is a clear tendency that more and more real-time services are making the jump from dedicated circuit-switched and broadcasting networks into packet switching. Examples are telephony, videoconferencing, and television. The Internet today is thus hosting a large set of different services, including the delay tolerant Web-surfing traffic, but also the non-delay tolerant real-time services. An additional challenge with most real-time traffic is that its traffic pattern do not adapt to the varying traffic load as Web-traffic do. Still, these new services work well, as long as the packet switching capacity is sufficient. Problems arise when the growth of real-time service usage is larger than the capacity increase. During peak hours, users will then start to experience media services fall-out and excessive communication delay.
The reason is that the Internet as we know it today was not built to handle such services at all. In motor traffic, as a comparison, queues build up when the traffic load is larger than the road and crossover capacity. The Internet behaves in a similar fashion: information is sent in packets that can be compared to cars. If too many packets are heading the same direction, queues of packets build up in the Internet routers, causing extra delay during such peak hours. In one way the Internet is more fearful than motor traffic: if queues get too long, new arriving packets are simply dropped, i.e. they just vanish. Luckily, there is no direct parallel to this phenomenon in the motor traffic comparison realm! To assist the queuing problems in motor traffic, special traffic lanes can be defined to allow e.g. only buses, taxis, and cars where the driver has at least one passenger, to drive in that lane.
Thus, these road-users will experience less delay in peak hours than the rest of the population. The Internet is tried “healed” with some comparable means. E.g. with the use of IntServ or DiffServ Quality of Service, packets belonging to high priority applications are treated in a preferential fashion. But what happens if too many applications start to use these “special-lanes”? What if the total capacity is over-loaded over a significant time period? The answer to fix the problem is simple: the aggregate traffic generation must slow down! In motor traffic, this means that each car carries more people (i.e. fewer cars in total), or, equivalently, that big cars are exchanged by smaller cars, thus producing smaller queues. In the multimedia real-time packet switching realm, the equivalent solution is that the same content must be compressed more efficiently, thus producing fewer and/or smaller packets.
This thesis proposes a solution for live interactive real-time streaming media where a tight interaction between the media sources and the network is very essential. A novel router architecture, “P-AQM”, for packet switched networks is its core component. The primary P-AQM design objective is native support for rate adaptive real-time multimedia flows, addressing low queuing delay and low packet losses even at high traffic load to assist conversational media flows. The second objective is bandwidth fairness among the media flows, but also fairness to elastic (TCP) flows. These two design objectives are achieved due to the aforementioned interaction between the network routers and the traffic sources: the routers signal the traffic congestion level, while the media and TCP sources apply rate adaption. TCP has built-in congestion control mechanism (e.g. Tahoe or Reno) that reacts on packet drops or packet ECN tags performed by the router. Real-time media using the UDP protocol has no standardized congestion control mechanism. While DCCP/TFRC has become a compelling IETF standard during the last years, the work of this thesis has chosen another solution for media rate control that bypasses the TFRC performance. Using the traffic congestion level signals from P-AQM routers, the media rate control can be done much more precise, react faster to traffic load changes, and obtain intra-flow global max-min fairness. The cost of these improvements is gradual deployment of the new P-AQM packet switching routers, and some added signaling traffic.
The P-AQM design is following classical control theory principles, and has been developed and improved using a combination of analytical and simulation tools. As a side effect to the need for true decodable rate adaptive video traffic, a simulation framework and tool-set, “Evalvid-RA”, was developed to generate such traffic. Evalvid-RA can also assist other researchers in improving their own work, e.g. applying rate adaptive video codecs over the DCCP/TFRC protocol.
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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.
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An increasing number of network applications use reliable transport protocols. Applications with constant data transmission recover from loss without major performance disruption, however, applications that send data sporadically, in small packets, also called thin-streams, experience frequently high latencies due to 'Bufferbloat', that reduce the application performance. Active Queue Management mechanisms were proposed to dynamically manage the queues in routers by dropping packets early and reduce these, hence reducing latency. While their deployment to the internet remains an open issue, the proper investigation into how their functioning mechanism impacts latency is the main focus of this work and research questions have been devised to investigate the AQM impact on latency. A range of AQM mechanisms has been evaluated by the research, exploring performance of the methods for latency sensitive network applications. This has explored new single queue AQM mechanisms such as Controlled Delay (CODEL) and Proportional Integral Enhanced (PIE) and Adaptive RED (ARED). The evaluation has shown great improvements in queuing latency when AQM are used over a range of network scenarios. Scheduling AQM algorithms such as FlowQueue CODEL (FQ-CODEL) isolates traffic and minimises the impact of Bufferbloat on flows. The core components of FQ-CODEL, still widely misunderstood at the time of its inception, have been explained in depth by this study and their contribution to reducing latency have been evaluated. The results show significant reductions in queuing latency for thin streams using FQ-CODEL. When TCP is used for thin streams, high application latencies can arise when there are retransmissions, for example after dropping packets by an AQM mechanism. This delay is a result of TCP's loss-based congestion control mechanism that controls sender transmission rate following packet loss. ECN, a marking sender-side improvement to TCP reduces applicationlayer latency without disrupting the overall network performance. The thesis evaluated the benefit of using ECN using a wide range of experiments. The findings show that FQ-CODEL with ECN provides a substantial reduction of application latency compared to a drop-based AQM. Moreover, this study recommends the combination of FQ-CODEL with other mechanisms, to reduce application latency. Mechanisms such as ABE, have been shown to increase aggregate throughput and reduce application latency for thin-stream applications.
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Chen, Qiang. "Active queue management methods in computer communication networks based on pole placement and H-infinity optimal control." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/29343.
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This thesis studies the control of TCP traffic in the Internet nowadays. Both classical and modern control theory are used to design the controllers for the TCP/AQM system.
For the classical control theoretical approaches, we revisit the simple pole placement technique, and exploit this technique to propose four kinds of controllers for active queue management (AQM) in IP routers: the Proportional controller based on Pole Placement (the P_PP controller), the Proportional-plus-integral controller based on Pole Placement (the PI_PP controller), the Self Tuning Proportional controller based on Pole Placement (the ST_P_PP controller), and the Self-Tuning Proportional-plus-Integral controller based on Pole Placement (the ST_PI_PP controller). The transient performance indices---the damping ratio xi and the undamped natural frequency on, are appropriately chosen such that: (a) the transient response of the system is satisfied; (b) all the poles lie in the left-half of the s-plane to guarantee the stability of the system. The self-tuning controllers (the ST_P_PP and the ST_PI_PP) can maintain on-line tuning of the controller parameters so that good system performance can be ensured even under significant load changes.
This thesis also investigates the application of a robust modern control technique--- Hinfinity optimal control to the AQM controller. Two Hinfinity loop-shaping techniques, the S/U Mixed Sensitivity Problem (MSP) and the S/T/U MSP are applied to the controller design. Different weight functions and their impacts on the system performance are discussed and evaluated.
Finally, by modeling the uncertainties in the TCP/AQM system in terms of the uncertainty weight, this thesis also designs a robust AQM controller based on a modern control technique---robust mu analysis. The controller is synthesized by approximating the mu-optimal control problem with the Hinfinity S/T/U MSP. The NP (Nominal Performance), the RS (Robust Stability) and the RP (Robust Performance) of the system under the synthesized controller are analyzed using the mu analysis technique.
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Abdel-Jaber, Hussein F. "Performance Modelling and Evaluation of Active Queue Management Techniques in Communication Networks. The development and performance evaluation of some new active queue management methods for internet congestion control based on fuzzy logic and random early detection using discrete-time queueing analysis and simulation." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/4261.
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Since the field of computer networks has rapidly grown in the last two decades, congestion control of traffic loads within networks has become a high priority. Congestion occurs in network routers when the number of incoming packets exceeds the available network resources, such as buffer space and bandwidth allocation. This may result in a poor network performance with reference to average packet queueing delay, packet loss rate and throughput. To enhance the performance when the network becomes congested, several different active queue management (AQM) methods have been proposed and some of these are discussed in this thesis. Specifically, these AQM methods are surveyed in detail and their strengths and limitations are highlighted. A comparison is conducted between five known AQM methods, Random Early Detection (RED), Gentle Random Early Detection (GRED), Adaptive Random Early Detection (ARED), Dynamic Random Early Drop (DRED) and BLUE, based on several performance measures, including mean queue length, throughput, average queueing delay, overflow packet loss probability, packet dropping probability and the total of overflow loss and dropping probabilities for packets, with the aim of identifying which AQM method gives the most satisfactory results of the performance measures. This thesis presents a new AQM approach based on the RED algorithm that determines and controls the congested router buffers in an early stage. This approach is called Dynamic RED (REDD), which stabilises the average queue length between minimum and maximum threshold positions at a certain level called the target level to prevent building up the queues in the router buffers. A comparison is made between the proposed REDD, RED and ARED approaches regarding the above performance measures. Moreover, three methods based on RED and fuzzy logic are proposed to control the congested router buffers incipiently. These methods are named REDD1, REDD2, and REDD3 and their performances are also compared with RED using the above performance measures to identify which method achieves the most satisfactory results. Furthermore, a set of discrete-time queue analytical models are developed based on the following approaches: RED, GRED, DRED and BLUE, to detect the congestion at router buffers in an early stage. The proposed analytical models use the instantaneous queue length as a congestion measure to capture short term changes in the input and prevent packet loss due to overflow. The proposed analytical models are experimentally compared with their corresponding AQM simulations with reference to the above performance measures to identify which approach gives the most satisfactory results. The simulations for RED, GRED, ARED, DRED, BLUE, REDD, REDD1, REDD2 and REDD3 are run ten times, each time with a change of seed and the results of each run are used to obtain mean values, variance, standard deviation and 95% confidence intervals. The performance measures are calculated based on data collected only after the system has reached a steady state. After extensive experimentation, the results show that the proposed REDD, REDD1, REDD2 and REDD3 algorithms and some of the proposed analytical models such as DRED-Alpha, RED and GRED models offer somewhat better results of mean queue length and average queueing delay than these achieved by RED and its variants when the values of packet arrival probability are greater than the value of packet departure probability, i.e. in a congestion situation. This suggests that when traffic is largely of a non bursty nature, instantaneous queue length might be a better congestion measure to use rather than the average queue length as in the more traditional models.
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Kuchár, Peter. "Simulace síťového prvku v prostředí Matlab." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-218829.
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Master’s thesis is dedicated to the issue of network element. In the first part are described technological aspects as the internal structure of network elements and control mechanisms that provide differentiaton of services and support their quality requirements. In the first chapter are listed control mechanisms from most simple like FIFO to the more sophisticated like CBWFQ. Active queue managements are not missing and they are described in the section Riadiaci člen. Significant role in the differentiation of services have processes marking and pakets classification. The second chapter is devoted most promising standard DiffServ. Contains section devoted to architecture, paket marking, code point DSCP and the final part is devoted to the types of per-hop behavior and it is expedited forwarding EF and technique assured forwarding AF. The third chapter gives an overview common models of neural networks, their properties and assess their suitability for deployment in network elements. The routher design itself and its structure in programming environment Matlab/Simulink is the subject of the fourth chapter. Except used bloks from Simulink library is described their setting and function in the wiring. Consequently results are reviewied and conclusions drawn.
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Chen, Zhenyu. "Discrete-time queueing model for responsive network traffic and bottleneck queues." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/21314.
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The Internet has been more and more intensively used in recent years. Although network infrastructure has been regularly upgraded, and the ability to manage heavy traffic greatly increased, especially on the core networks, congestion never ceases to appear, as the amount of traffic that flow on the Internet seems to be increasing at an even faster rate. Thus, congestion control mechanisms play a vital role in the functioning of the Internet. Active Queue Management (AQM) is a popular type of congestion control mechanism that is implemented on gateways (most notably routers), which can predict and avoid the congestion before it happens. When properly configured, AQMs can effectively reduce the congestion, and alleviate some of the problems such as global synchronisation and unfairness to bursty traffic. However, there are still many problems regarding AQMs. Most of the AQM schemes are quite sensitive to their parameters setting, and these parameters may be heavily dependent on the network traffic profile, which the administrator may not have intensive knowledge of, and is likely to change over time. When poorly configured, many AQMs perform no better than the basic drop-tail queue. There is currently no effective method to compare the performance of these AQM algorithms, caused by the parameter configuration problem. In this research, the aim is to propose a new analytical model, which mainly uses discrete-time queueing theory. A novel transient modification to the conventional equilibrium-based method is proposed, and it is utilised to further develop a dynamic interactive model of responsive traffic and bottleneck queues. Using step-by-step analysis, it represents the bursty traffic and oscillating queue length behaviour in practical network more accurately. It also provides an effective way of predicting the behaviour of a TCP-AQM system, allowing easier parameter optimisation for AQM schemes. Numerical solution using MATLAB and software simulation using NS-2 are used to extensively validate the proposed models, theories and conclusions.
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QUET, Pierre-Francois D. "A ROBUST CONTROL THEORETIC APPROACH TO FLOW CONTROLLER DESIGNS FOR CONGESTION CONTROL IN COMMUNICATION NETWORKS." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1032194223.
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Diego, Maza William David. "Contrôle de trafic et gestion de la qualité de service basée sur les mécanismes IP pour les réseaux LTE." Thesis, Télécom Bretagne, 2016. http://www.theses.fr/2016TELB0406/document.
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Depuis quelques années le trafic de l'internet mobile ne cesse d'augmenter. Cette croissance soutenue est liée à plusieurs facteurs, parmi lesquels l'évolution des terminaux, la grande diversité des services et des applications disponibles et le déploiement des nouvelles technologies d'accès radio mobile (3G/4G). À cet égard, le standard 3GPP pour les réseaux LTE propose une architecture offrant une gestion fine de la QoS (par flux). Ce modèle, hérité des réseaux mobiles traditionnels orientés connexion, soulève des problèmes en termes de scalabilité, efficacité et performances. Les travaux entrepris dans cette thèse ont pour objectif principal de proposer des solutions plus simples et moins coûteuses pour la gestion de la QoS dans les réseaux mobiles. À cette fin, à l'issue d'une étude et de l'évaluation de l'impact de la signalisation associée au modèle de QoS standard, deux modèles alternatifs ont été proposés. Nous proposons tout d'abord un modèle basée sur les mécanismes IP inspiré de l'approche DiffServ (par agrégat) largement étudié dans les réseaux IP fixes. Ce modèle fournit une gestion de la QoS simple, efficiente et rentable, tout en garantissant des performances équivalentes au modèle standard. Cependant, elle nécessite une remise à niveau de tous les eNB, et donc une longue phase de transition. En conséquence, nous proposons SloMo qui vise à améliorer l'expérience des clients mobiles, mais avec un objectif de déploiement plus rapide. SloMo est une solution de gestion implicite de la QoS depuis un point unique situé sur le chemin des communications. SloMo exploite la dynamique instaurée par le mécanisme de contrôle de flux de TCP. Il vise à recréer un goulot d'étranglement dynamique dans un équipement contrôlé par l'opérateur lorsque les points de congestion réels ne sont pas accessibles. Une fois ce goulot d'étranglement déporté, il est alors aisé d'effectuer une gestion de la qualité IP classique dans l'équipement supportant Slo-MoThe mobile data landscape is changing rapidly and mobile operators are today facing the daunting challenge of providing cheap and valuable services to ever more demanding customers. As a consequence, cost reduction is actively sought by operators as well as Quality of Service (QoS) preservation. Current 3GPP standards for LTE/EPC networks offer a fine tuning QoS (per-flow level), which inherits many characteristics of legacy telco networks. In spite of its good performance, such a QoS model reveals costly and cumbersome and finally, it remains very rarely deployed, thereby giving way to basic best-effort hegemony. This thesis aims at improving QoS in mobile networks through cost-effective solutions; To this end, after an evaluation of the impact and cost of signaling associated with the standard QoS model, alternative schemes are proposed, such as the IP-centric QoS model (per aggregate) inspired from the DiffServ approach widely used in fixed IP networks. This model provides a simple, efficient and cost-effective IP level QoS management with a performance level similar to standardized solutions. However, as it requires enhancements in the eNB, this scheme cannot be expected in mobile networks before a rather long time.Thus, we introduce Slo-Mo, which is a lightweight implicit mechanism for managing QoS from a distant point when the congestion point (e.g. eNB) is not able to do it. Slo-Mo creates a self-adaptive bottleneck which adjusts dynamically to the available resources taking advantage of TCP native flow control. Straightforward QoS management at IP level is then performed in the Slo-Mo node, leading to enhanced customer experience at a marginal cost and short term
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Lee, Choong-Soo. "WHITE : achieving fair bandwidth allocation with priority dropping based on round trip times." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0430102-193829.
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Ariba, Yassine. "Sur la stabilité des systèmes à retards variant dans le temps : théorie et application au contrôle de congestion d'un routeur." Phd thesis, Université Paul Sabatier - Toulouse III, 2009. http://tel.archives-ouvertes.fr/tel-00442454.
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Cette thèse s'inscrit dans une thématique pluridisciplinaire explorant les liens existants entre la théorie de la commande et les réseaux informatiques. L'idée consiste à appliquer les outils de l'Automatique pour la stabilisation du trafic dans les réseaux de communication. Premièrement, nous nous sommes intéressés à l'analyse de stabilité des systèmes à retards variables au travers de deux approches temporelles. D'une part, nous avons considéré la méthode de Lyapunov-Krasovskii dans laquelle nous avons élaboré des fonctionnelles en adéquation avec de nouvelles modélisations du système (segmentation du retard, dérivée temporelle). D'autre part, la stabilité a également été abordée avec une approche entrée-sortie, empruntant alors les outils de l'analyse robuste. Le système à retard est alors réécrit comme l'interconnexion d'une application linéaire avec une matrice constituée d'opérateurs définissant le système original. Après avoir revisité le principe de séparation quadratique, nous développons des opérateurs auxiliaires afin de caractériser au mieux la dynamique retardée et proposer des critères moins pessimistes. Deuxièmement, la méthodologie développée est ensuite utilisée pour le problème de contrôle de congestion d'un routeur lors de communications TCP. Ce protocole de bout en bout est sensible à la perte de paquet et modifie en conséquence son taux d'émission selon l'algorithme du AIMD. Il s'agit alors de commander le taux de perte par l'intermédiaire d'un mécanisme d'Active Queue Management situé au niveau du routeur afin de réguler le trafic. Les résultats théoriques sont ensuite évalués à l'aide du simulateur de réseaux NS-2.
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Li, Jian. "Garantir la qualité de service temps réel selon l'approche (m,k)-firm." Phd thesis, Institut National Polytechnique de Lorraine - INPL, 2007. http://tel.archives-ouvertes.fr/tel-00140318.
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Cette thèse se focalise sur le développement des algorithmes d'ordonnancement sous contrainte (m, k)-firm, ainsi que leurs applications pour la gestion de la qualité de service (QdS) dans les réseaux et systèmes temps réel distribués. L'objectif recherché est la ga-rantie déterministe de la QdS tout en maintenant un fort taux d'utilisation des ressources.Les contributions sont (1) l'établissement d'une condition suffisante d'ordonnançabilité d'un ensemble de tâches sous l'algorithme « distance based priority »; (2) la définition de R-(m, k)-firm, un nouveau modèle qui relâche la contrainte (m, k)-firm et qui permet de modéliser de façon plus juste des exigences du temps réel souple; (3) le développement d'un algorithme efficace de dimensionnement de ressources sous contrainte (m, k)-firm relâchée; (4) la proposition de « Double Leaks Bucket » pour la gestion active de files d'attente permettant de maintenir une QdS en cas de surcharge des réseaux.
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Wang, Jiang. "An adaptive active queue management algorithm in Internet." Mémoire, 2006. http://www.archipel.uqam.ca/3071/1/M9440.pdf.
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Hou, Jia Ling, and 侯佳伶. "Evaluation on Active Queue Management." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/98167766235705069353.
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碩士國立臺灣海洋大學
資訊工程學系
100
This paper focused on a system of active queue management (AQM) router nonlinear TCP network, try to use the Takagi-Sugeno (T-S) fuzzy model to construct a similar techniques mathematical model. The results showed that T-S fuzzy model can offer better approximation than the linear dynamic model. Based on the successful construction of T-S fuzzy model, T-S fuzzy controller design methods have in the development of AQM router, this paper proposed that the T-S fuzzy control architecture is a parallel distributed compensation (PDC) concept and iterative linear matrix inequality (ILMI) algorithm to achieve. Finally, we deploy with dummynet and using iperf to observe the flow situation under real traffic conditions, the general assessment of this method is widely used in network performance between AQM mechanisms of quality.
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Chang, Pen-Ming, and 張本明. "QoS-Aware Active Queue Management for Multimedia Services." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/13649677375222553729.
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碩士元智大學
資訊工程學系
97
隨著IPTV或是視訊會議等應用程式越來越普及，所以多媒體影音串流已經變成網路上主要的流量。這類應用服務通常採用群體廣播技術傳遞影音內容以增加頻寬的使用效率，除此之外，對於其服務品質例如封包的延遲時間，頻宽需求有著比較嚴格要求。從頻寬的使用效率而言，應該要針對採用群體廣播連線提供更佳的服務。然而目前Best-effort的網路環境除了無法提供服務品質的保證，也不能對於採用群體廣播連線提供更佳的服務品質。因此，在這篇論文中提出一個針對多媒體及採用群體廣播連線的服務的多佇例，多門檻值主動式佇例管理配合公平權重排程演算法以保證服務品質。
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Chen, Zhi-Yi, and 陳志毅. "Active Queue Management with Weights to Provide Differentiated Services." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/15940348252466896781.
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碩士義守大學
電機工程學系碩士班
95
Nowadays, the multimedia networks are common. To satisfy the different requirements in the multimedia networks, the QoS control mechanisms are necessary. Among these, the active queue management (AQM) plays an important role. Therefore, this thesis modifies the algorithm “GREEN (Global Random Early Estimation for Nipping).” GREEN enhances the concept of “Early” to “Early Estimation” by early estimating the network status. The network status obtained by estimation is earlier than by detection. In this way, the decision in the AQM can be made more quickly. After modification, the algorithm iss more stable than original GREEN and still keeps the original good features. This thesis also proposes a novel AQM algorithm named PASS (drop with Probability And StatisticS). In general, AQM should drop packet with random. We classify the random manner into two types: probability and statistics. For TCP flows, PASS drops the packets with probability, and for UDP flows PASS drops packets statistics. This method should works even for the networks without DiffServ. PASS uses the “match drop” like CHOKe and CHOKeW. But the difference is that the match drop of PASS just uses for UDP flows and there are no comparisons of flow id. In this way, the throughput of unresponsive flows is suppressed to protect TCP flows like CHOKe and CHOKeW. Furthermore, the overall algorithm is more efficiency.
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Yu, Chia-chun, and 余佳純. "A Proportional Rate-based Control for Active Queue Management." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/83964262050715635421.
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Akin, Ozdemir. "Active queue management and scheduling methods for packet-switched networks." 2004. http://www.lib.ncsu.edu/theses/available/etd-12122004-202307/unrestricted/etd.pdf.
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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.
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碩士國立中興大學
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.
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Chen, Fu-chi, and 陳福吉. "A Fuzzy Controller for Improving Queue Length Stability and Packet Delay of RED's Active Queue Management." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/85034543437552997092.
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碩士國立成功大學
資訊管理研究所
95
As network technique blooming, our livings are facilitated with the networks, which make the internet become an important infrastructure to the global industry transaction. As a result the demands of network bandwidth are increasing because of several communication protocols, Voice over Internet Protocol (VoIP), Video conferencing, Video on Demand (VoD), require wideband transmission. Therefore, planning and control for the Quality of Service (QoS) has become a research area. One way to avoiding flow congestion is using Random Early Detection (RED). In RED, when the average queue lies in between Min and Max, packets dropping probability exists a non-linear relationship between flows of network and queues. This research constructed a new active queue manage method. Based on RED mechanism, the packets loss rate between two thresholds is computed by Fuzzy Proportional Integral Integral Derivative. The fuzzy controller has advantages of processing non-linear relationship by using fuzzy algorithm and controlling queues in buffer to be near the target by PIID. Evaluated the performance of Fuzzy PIID RED was conducted in the study. By simulation using ns2, this study also compared it with some popular AQM methods, such as RED and PI. The result of simulation shows good performance and significant improvement in the field of fairness, queue behavior, delay time of end to end and jitters. The problem concerning Look-Out of DropTail and Full Queue was also improved. The approach solves the problem of the difficulty of setting two thresholds in RED as well. The packets dropping probability using proposed controller also conforms non-linear relationship between flows of network and queues. In summary, Fuzzy PIID RED can control queue behavior effectively.
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Wang, Lan, Geyong Min, and Irfan U. Awan. "Modeling and Analysis of Active Queue Management Schemes under Bursty Traffic." 2006. http://hdl.handle.net/10454/3734.
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NoTraffic congestion arising from the shared nature of uplink channels in wireless networks can cause serious problems for the provision of QoS to various services. One approach to overcome these problems is to implement some effective congestion control mechanisms at the downlink buffer at the mobile network link layer or at gateways on the behalf of wireless network access points. Active queue management (AQM) is an effective mechanism to support end-to-end traffic congestion control in modern high-speed networks. Initially developed for Internet routers, AQM is now being also considered as an effective congestion control mechanism to enhance TCP performance over 3G links. This paper proposes an analytical performance model for AQM using various dropping functions. The selection of different dropping functions and threshold values required for this scheme plays a critical role on its effectiveness. The model uses a well-known Markov-modulated Poisson process (MMPP) to capture traffic burstiness and correlations. The validity of the model has been demonstrated through simulation experiments. Extensive analytical results have indicated that exponential dropping function is a good choice for AQM to support efficient congestion control.
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Lin, Hsin-Chih, and 林信志. "A-PIE: An Adaptive Active Queue Management Algorithm for Communication Networks." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/hemg9x.
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碩士國立交通大學
電機學院電信學程
106
Active queue management (AQM) could mitigate the bufferbloat problem and enhance the quality of experience for network applications. In comparison with other AQM algorithms, the Proportional Integral Controller Enhanced (PIE) algorithm has been shown to better manage the queuing delay without sacrificing channel efficiency. However, when deploying the PIE algorithm to a network equipment, key parameters such as Reference Queuing Delay have to be tuned before operation and cannot be modified afterwards. In this thesis, we address the flaws of the PIE algorithm and propose a novel adaptive PIE algorithm. We observe that the Reference Queuing Delay should adapt to the network state. In addition, we propose the partial Round Trip Time (RTT) estimation method for queue length adjustment. Furthermore, we use the well-known ns-2 network simulator to evaluate the revised PIE algorithm. Our study shows that the proposed A-PIE algorithm significantly outperforms the original PIE algorithm.
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Li, Chun-Wei. "System design and performance analysis of Transmission Control Protocol with Active Queue Management." 2004. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2307200415560700.
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Li, Chun-Wei, and 李君威. "System design and performance analysis of Transmission Control Protocol with Active Queue Management." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/65qp4q.
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碩士國立臺灣大學
電機工程學研究所
92
System design and performance analysis of Transmission Control Protocol with Active Queue Management Student: Chun-Wei Li Advisor: Feng-Li Lian Department of Electrical Engineering National Taiwan University ABSTRACT In this thesis, we first introduce current networks architecture and briefly explain the functions of each network layer. We mainly focus on the transport layer of the ISO/OSI seven layers. We list some important TCP algorithms such as TCP-Reno and AQM algorithms such as the RED algorithm. We look into the nonlinear dynamics in a discrete-time network model combined with Reno and RED. The system is regarded as the deterministic closed-loop system. We investigate its stability regions. First, we use linearized error dynamical vector-matrix model to present the nonlinear systems and discuss its feedback properties in terms of network parameters such as link capacity, number of senders, and round trip time. Second, we use the z-transform to transform the derived dynamical equations into the transfer function format. Thus, we can investigate the stability of the system by plotting Bode plot or Nichols chart of the transfer function and use the characteristic equation to find the poles of the system. Based on the location of the poles we can observe the parameter effects on the system performance. Besides, the pole location effects are also discussed by observing the damping ratio and natural frequency of the system. We also change the initial conditions to observe the difference in the normal case. Finally we investigate the equilibrium condition variations when the parameters are changed and the system performance on RED and network parameters are changed. We present NS-2 simulations to support our analysis. Key words: TCP congestion control, AQM, control theory, nonlinear analysis
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Oruganti, Sai S. "Performance of robust active queue management schemes and window adaptation schemes in IP network." 2003. http://www.lib.ncsu.edu/theses/available/etd-12162003-173014/unrestricted/etd.pdf.
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Xu, Kai. "TCP performance enhancement in wireless networks via adaptive congestion control and active queue management." Thesis, 2005. http://library1.njit.edu/etd/fromwebvoyage.cfm?id=njit-etd2005-088.
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Aung, Lily Kheng-Hwar. "A case study of active traffic management : safety analysis and operations improvements using a queue warning system." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-08-4192.
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Active traffic management is a hot topic for addressing issues of highway congestion. It is the use of intelligent transportation systems to provide real time traffic information on highway conditions. In Austin, the segment of Interstate 35 between Riverside Drive and State Highway 71 experiences both congestion and safety issues. This report provides an introduction into the application of active traffic management through the use of a proposed queue warning system in the area. First, select crash data on the region is highlighted to present the safety conditions, particularly the type of collision and crash severity involved. Next, a proposed queue warning system design is described. This includes a description of the equipment used, methodology for system deployment, and expected outcomes. Finally, a computer simulation testing the operational performance of the queue warning system is performed using VISSIM, and the results are reported. This report aims to demonstrate the role that queue warning system and active traffic management may play in addressing metropolitan traffic needs.text
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Chen, Jian. "Active queue management techniques to improve Quality of Service for real-time flows in third generation wireless networks." Thesis, 2002. http://hdl.handle.net/2429/12416.
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In this thesis, we analyze the behavior of real-time flows with hard time deadline
using link layer retransmission to overcome wireless errors, and propose two new mechanisms
to improve these flows' end-to-end Quality-of-Service (QoS) over a wireless network.
Wireless channels have the characteristic that link quality varies according to propagation
conditions. For real-time flows with hard time deadlines, link layer retransmissions
over a wireless network, necessitated by fluctuations in link quality, may result in a high
number of packets being dropped, as deadlines expire. The expired packets waste network
resources and lead to long queuing delays for subsequent packets. After analyzing the characteristics
of the Radio Link Control (RLC) layer of the General Packet Radio Service
(GPRS)/Universal Mobile Telecommunication Services (UMTS) network, we have developed
a new set of mechanisms to minimize expiration packet drops in favour of overflowlike
packet drops. We propose to use active queue management to limit transmission queue
length, hence queuing delay, thus eliminating expiration packet drops. This allows the
buffer and wireless bandwidth, otherwise be wasted by expiring packets, to be released earlier
for other packets. We apply this mechanism to the radio link control layer in the GPRS/
UMTS wireless networks. The effectiveness of the proposed mechanism is verified by simulations.
Furthermore, we extend the similar idea from the radio link control layer to the
whole GPRS/UMTS domain. We adapt the Early Regulation of Unresponsive Flows (ERUF)
to the characteristics of wireless channels employing link layer retransmissions. We propose
to regulate those congested flows at the DiffServ domain ingress edge nodes of the GPRS/UMTS core network, and drop undeliverable packets earlier to release some shared
network resources for other flows. We also present simulation results to show that this new
Wireless Early Regulation of Unresponsive Flows (WERUF) scheme can significantly
improve the overall end-to-end quality-of-service.
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Bouacida, Nader. "Towards Controlling Latency in Wireless Networks." Thesis, 2017. http://hdl.handle.net/10754/623271.
Full textAbstract:
Wireless networks are undergoing an unprecedented revolution in the last decade. With the explosion of delay-sensitive applications in the Internet (i.e., online gaming and VoIP), latency becomes a major issue for the development of wireless technology. Taking advantage of the significant decline in memory prices, industrialists equip the network devices with larger buffering capacities to improve the network throughput by limiting packets drops. Over-buffering results in increasing the time that packets spend in the queues and, thus, introducing more latency in networks. This phenomenon is known as “bufferbloat”. While throughput is the dominant performance metric, latency also has a huge impact on user experience not only for real-time applications but also for common applications like web browsing, which is sensitive to latencies in order of hundreds of milliseconds.
Concerns have arisen about designing sophisticated queue management schemes to mitigate the effects of such phenomenon. My thesis research aims to solve bufferbloat problem in both traditional half-duplex and cutting-edge full-duplex wireless systems by reducing delay while maximizing wireless links utilization and fairness. Our work shed lights on buffer management algorithms behavior in wireless networks and their ability to reduce latency resulting from excessive queuing delays inside oversized static network buffers without a significant loss in other network metrics.
First of all, we address the problem of buffer management in wireless full-duplex networks by using Wireless Queue Management (WQM), which is an active queue management technique for wireless networks. Our solution is based on Relay Full-Duplex MAC (RFD-MAC), an asynchronous media access control protocol designed for relay full-duplexing. Compared to the default case, our solution reduces the end-to-end delay by two orders of magnitude while achieving similar throughput in most of the cases.
In the second part of this thesis, we propose a novel design called “LearnQueue” based on reinforcement learning that can effectively control the latency in wireless networks. LearnQueue adapts quickly and intelligently to changes in the wireless environment using a sophisticated reward structure. Testbed results prove that LearnQueue can guarantee low latency while preserving throughput.
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Asfand-E-Yar, Irfan U. Awan, and Mike E. Woodward. "Performance modelling of a multiple threshold RED mechanism for bursty and correlated Internet traffic with MMPP arrival process." 2006. http://hdl.handle.net/10454/479.
Full textAbstract:
Access to the large web content hosted all over the world by users of the Internet engage
many hosts, routers/switches and faster links. They challenge the internet backbone to operate at
its capacity to assure e±cient content access. This may result in congestion and raises concerns over
various Quality of Service (QoS) issues like high delays, high packet loss and low throughput of the
system for various Internet applications. Thus, there is a need to develop effective congestion control
mechanisms in order to meet various Quality of Service (QoS) related performance parameters. In this
paper, our emphasis is on the Active Queue Management (AQM) mechanisms, particularly Random
Early Detection (RED). We propose a threshold based novel analytical model based on standard RED
mechanism. Various numerical examples are presented for Internet traffic scenarios containing both the
burstiness and correlation properties of the network traffic.