Tesi: "Network control protocol"

1

Nguyen, Long G. "Designing a higher layer protocol for small distributed microcontroller systems using the control area network protocol". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 1998. https://ro.ecu.edu.au/theses/1603.

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This thesis is concerned with designing a Higher Layer Protocol (HLP) for small distributed microcontroller systems using a well-established network protocol: the Controller Area Network (CAN) protocol which, currently, is widely used in the automation industries. Steps were taken to investigate three popular HLPs based on the CAN protocol: namely. Smart Distributed System (SDS), DeviceNet. and CAN Kingdom. Following the comparison of the three HLPs, the CAN Kingdom protocol was chosen for the task of designing the HLP in this project in order to satisfy the restrictions associated with small systems. Thus, the HLP (named the Small CAN Kingdom protocol) of this project was designed according to the principles of the CAN Kingdom protocol, which contains many advantages for open network solutions. This enables designers to enhance a system's performance relatively easily. A complete hardware and software design of a small CAN-based system, utilising the Motorola MC68HC 11 microcontrollers, the Intel 82527 CAN controller chips, and DS3695 (RS485 standard) transceivers has been described. This small system can be used to demonstrate the performance of the Small CAN Kingdom protocol. The development of the system software has also taken into account the rules associated with this protocol.

2

Iyengar, Janardhan R. "End-to-end concurrent multipath transfer using transport layer multihoming". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 1.67 Mb., p. 123, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3220807.

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3

Brownfield, Michael I. "Energy-efficient Wireless Sensor Network MAC Protocol". Diss., This resource online, 2006. http://scholar.lib.vt.edu/theses/available/etd-04102006-170423/.

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4

Lai, Chengdi, e 赖成迪. "Congestion control for transmission control protocol (TCP) in wirelessnetworks". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47102445.

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The best MPhil thesis in the Faculties of Dentistry, Engineering, Medicine and Science (University of Hong Kong), Li Ka Shing Prize,2010-11.
published_or_final_version
Electrical and Electronic Engineering
Master
Master of Philosophy

5

Halepoto, Imtiaz Ali. "Scheduling and flow control in CMT-SCTP". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/210189.

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6

Che, Xianhui. "Control protocol for optical packet switched local area network". Thesis, University of Essex, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438262.

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7

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).

8

Cox, Spencer L. "User Datagram Protocol with Congestion Control". Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1250.pdf.

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9

Zhou, Kaiyu. "Packet loss models of the Transmission Control Protocol". Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36873172.

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10

Zhou, Kaiyu, e 周開宇. "Packet loss models of the Transmission Control Protocol". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B36873172.

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11

Bickhart, Ryan W. "Transparent TCP-to-SCTP translation shim layer". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 0.44 Mb, 82 p, 2005. http://wwwlib.umi.com/dissertations/fullcit/1428177.

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12

梁鉅輝 e Kui-fai Leung. "Enhancing transmission control protocol performance over wireless networks". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31227570.

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13

Eddy, Wesley M. "Improving Transport Control Protocol Performance With Path Error Rate Information". Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1087844627.

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14

Jourjon, Guillaume Electrical Engineering &amp 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.

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This thesis presents three main contributions that aim to improve the transport layer of the current networking architecture. The transport layer is nowadays dominated by the use of TCP and its congestion control. Recently new congestion control mechanisms have been proposed. Among them, TCP Friendly Hate Control (TFRC) appears to be one of the most complete. Nevertheless this congestion control mechanism, as with TCP, does not take into account either the evolution of the network in terms of Quality of Service and mobility or the evolution of the applications. The first contribution of this thesis is a specialisation of TFRC congestion control to provide a QoS-aware Transport Protocol specifically designed to operate over QoS-enabled networks with bandwidth guarantee mechanisms. This protocol combines a QoS-aware congestion control, which takes into account network-level bandwidth reservations, with full ordered reliability mechanism to provide a transport service similar to TCP. As a result, we obtain the guaranteed throughput at the application level where TCP fails. This protocol is t he first transport protocol compliant with bandwidth guaranteed networks. At the same time the set of network services expands, new technologies have been proposed and deployed at the physical layer. These new technologies are mainly characterised by communications done without wire constraint and the mobility of the end-systems. Furthermore, these technologies are usually deployed on entities where the CPU power and memory storage are limited. The second contribution of this thesis is therefore to propose an adaptation of TFHC to these entities. This is accomplished with the proposition of a new sender-based version of TFHC. This version has been implemented, evaluated and its numerous contributions and advantages compare to usual TFHC version have been demonstrated. Finally, we proposed an optimisation of actual implementations of TFHC. This optimisation first consists in the proposition of an algorithm based on a numerical analysis of the equation used in TFHC and the use of the Newton's algorithm. We furthermore give a first step, with the introduction of a new framework for TFRC, in order to better understand TFHC behaviour and to optimise the computation of the packet loss rate according to loss probability distributions.

15

Shi, Xiaohan. "A reliable real-time transport protocol for networked control systems over wireless networks". Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/60160/1/Xiaohan_Shi_Thesis.pdf.

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Deploying wireless networks in networked control systems (NCSs) has become more and more popular during the last few years. As a typical type of real-time control systems, an NCS is sensitive to long and nondeterministic time delay and packet losses. However, the nature of the wireless channel has the potential to degrade the performance of NCS networks in many aspects, particularly in time delay and packet losses. Transport layer protocols could play an important role in providing both reliable and fast transmission service to fulfill NCS’s real-time transmission requirements. Unfortunately, none of the existing transport protocols, including the Transport Control Protocol (TCP) and the User Datagram Protocol (UDP), was designed for real-time control applications. Moreover, periodic data and sporadic data are two types of real-time data traffic with different priorities in an NCS. Due to the lack of support for prioritized transmission service, the real-time performance for periodic and sporadic data in an NCS network is often degraded significantly, particularly under congested network conditions. To address these problems, a new transport layer protocol called Reliable Real-Time Transport Protocol (RRTTP) is proposed in this thesis. As a UDP-based protocol, RRTTP inherits UDP’s simplicity and fast transmission features. To improve the reliability, a retransmission and an acknowledgement mechanism are designed in RRTTP to compensate for packet losses. They are able to avoid unnecessary retransmission of the out-of-date packets in NCSs, and collisions are unlikely to happen, and small transmission delay can be achieved. Moreover, a prioritized transmission mechanism is also designed in RRTTP to improve the real-time performance of NCS networks under congested traffic conditions. Furthermore, the proposed RRTTP is implemented in the Network Simulator 2 for comprehensive simulations. The simulation results demonstrate that RRTTP outperforms TCP and UDP in terms of real-time transmissions in an NCS over wireless networks.

16

Li, Kang. "Modeling the bandwidth sharing behavior of congestion controlled flows /". Full text open access at:, 2002. http://content.ohsu.edu/u?/etd,632.

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17

Abou-Zeid, Al-Hussein A. "Stochastic models of congestion control in heterogeneous next generation packet networks /". Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/5994.

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18

Le, Dinh Tuan Computer Science &amp Engineering Faculty of Engineering UNSW. "Data reliability control in wireless sensor networks for data streaming applications". Publisher:University of New South Wales. Computer Science & Engineering, 2009. http://handle.unsw.edu.au/1959.4/43328.

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This thesis contributes toward the design of a reliable and energy-efficient transport system for Wireless Sensor Networks. Wireless Sensor Networks have emerged as a vital new area in networking research. In many Wireless Sensor Network systems, a common task of sensor nodes is to sense the environment and send the sensed data to a sink node. Thus, the effectiveness of a Wireless Sensor Network depends on how reliably the sensor nodes can deliver their sensed data to the sink. However, the sensor nodes are susceptible to loss for various reasons when there are dynamics in wireless transmission medium, environmental interference, battery depletion, or accidentally damage, etc. Therefore, assuring reliable data delivery between the sensor nodes and the sink in Wireless Sensor Networks is a challenging task. The primary contributions of this thesis include four parts. First, we design, implement, and evaluate a cross-layer communication protocol for reliable data transfer for data streaming applications in Wireless Sensor Networks. We employ reliable algorithms in each layer of the communication stack. At the MAC layer, a CSMA MAC protocol with an explicit hop-by-hop Acknowledgment loss recovery is employed. To ensure the end-to-end reliability, the maximum number of retransmissions are estimated and used at each sensor node. At the transport layer, an end-to-end Negative Acknowledgment with an aggregated positive Acknowledgment mechanism is used. By inspecting the sequence numbers on the packets, the sink can detect which packets were lost. In addition, to increase the robustness of the system, a watchdog process is implemented at both base station and sensor nodes, which enable them to power cycle when an unexpected fault occurs. We present extensive evaluations, including theoretical analysis, simulations, and experiments in the ﬁeld based on Fleck-3 platform and the TinyOS operating system. The designed network system has been working in the ﬁeld for over a year. The results show that our system is a promising solution to a sustainable irrigation system. Second, we present the design of a policy-based Sensor Reliability Management framework for Wireless Sensor Networks called SRM. SRM is based on hierarchical management architecture and on the policy-based network management paradigm. SRM allows the network administrators to interact with the Wireless Sensor Network via the management policies. SRM also provides a self-control capability to the network. This thesis restricts SRM to reliability management, but the same framework is also applicable for other management services by providing the management policies. Our experimental results show that SRM can offer sufficient reliability to the application users while reducing energy consumption by more than 50% compared to other approaches. Third, we propose an Energy-efficient and Reliable Transport Protocol called ERTP, which is designed for data streaming applications in Wireless Sensor Networks. ERTP is an adaptive transport protocol based on statistical reliability that ensures the number of data packets delivered to the sink exceeds the deﬁned threshold while reducing the energy consumption. Using a statistical reliability metric when designing a reliable transport protocol guarantees the delivery of adequate information to the users, and reduces energy consumption when compared to the absolute reliability. ERTP uses hop-by-hop Implicit Acknowledgment with a dynamically updated retransmission timeout for packet loss recovery. In multihop wireless networks, the transmitter can overhear a forwarding transmission and interpret it as an Implicit Acknowledgment. By combining the statistical reliability and the hop-by-hop Implicit Acknowledgment loss recovery, ERTP can offer sufficient reliability to the application users with minimal energy expense. Our extensive simulations and experimental evaluations show that ERTP can reduce energy consumption by more than 45% when compared to the state-of- the-art protocol. Consequently, sensor nodes are more energy-efficient and the lifespan of the unattended Wireless Sensor Network is increased. In Wireless Sensor Networks, sensor node failures can create network partitions or coverage loss which can not be solved by providing reliability at higher layers of the protocol stack. In the ﬁnal part of this thesis, we investigate the problem of maintaining the network connectivity and coverage when the sensor nodes are failed. We consider a hybrid Wireless Sensor Network where a subset of the nodes has the ability to move at a high energy expense. When a node has low remaining energy (dying node) but it is a critical node which constitutes the network such as a cluster head, it will seek a replacement. If a redundant node is located in the transmission range of the dying node and can fulﬁll the network connectivity and coverage requirement, it can be used for substitution. Otherwise, a protocol should be in place to relocate the redundant sensor node for replacement. We propose a distributed protocol for Mobile Sensor Relocation problem called Moser. Moser works in three phases. In the ﬁrst phase, the dying node determines if network partition occurs, ﬁnds an available mobile node, and asks for replacement by using ﬂooding algorithm. The dying node also decides the movement schedule of the available mobile node based on certain criteria. The second phase of the Moser protocol involves the actual movement of the mobile nodes to approach the location of the dying node. Finally, when the mobile node has reached the transmission of the dying node, it communicates to the dying nodes and moves to a desired location, where the network connectivity and coverage to the neighbors of the dying nodes are preserved.

19

Kuditipudi, Sasank. "Simulation for non-congestion losses control over Mobile Ad-Hoc Network using Transmission Control Protocol". Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10007412.

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Abstract (sommario):

Mobile Ad-hoc Network (MANET) is a group of individual mobile nodes that exhibit mobility, which results in network congestion. The nodes in MANET are continuously moving with change in network topology that results in significant network congestion. Transmission Control Protocol (TCP) is the most popular connection oriented transport layer protocol used today. The TCP when applied over MANET faces challenges, such as congestion and non-congestion losses. We are concentrating to distinguish between these losses and overcome the non-congestion losses.

The current project presents results on the performance evaluation of various TCP implementations, as measured in terms of the following parameters: end-to-end delay; throughput; network overhead; and packet delivery ratio. Simulations of applying the various TCP schemes over MANET have been performed using the Network Simulator (NS2), and simulation results including comparisons between the different TCP schemes are presented.

20

Medina, Andres. "Statistical approach to neighborhood congestion control in ad hoc wireless networks". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 54 p, 2008. http://proquest.umi.com/pqdweb?did=1456291921&sid=7&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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21

Gui, Li. "A transport protocol for real-time applications in wireless networked control systems". Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/45460/1/Li_Gui_Thesis.pdf.

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A Networked Control System (NCS) is a feedback-driven control system wherein the control loops are closed through a real-time network. Control and feedback signals in an NCS are exchanged among the system’s components in the form of information packets via the network. Nowadays, wireless technologies such as IEEE802.11 are being introduced to modern NCSs as they offer better scalability, larger bandwidth and lower costs. However, this type of network is not designed for NCSs because it introduces a large amount of dropped data, and unpredictable and long transmission latencies due to the characteristics of wireless channels, which are not acceptable for real-time control systems. Real-time control is a class of time-critical application which requires lossless data transmission, small and deterministic delays and jitter. For a real-time control system, network-introduced problems may degrade the system’s performance significantly or even cause system instability. It is therefore important to develop solutions to satisfy real-time requirements in terms of delays, jitter and data losses, and guarantee high levels of performance for time-critical communications in Wireless Networked Control Systems (WNCSs). To improve or even guarantee real-time performance in wireless control systems, this thesis presents several network layout strategies and a new transport layer protocol. Firstly, real-time performances in regard to data transmission delays and reliability of IEEE 802.11b-based UDP/IP NCSs are evaluated through simulations. After analysis of the simulation results, some network layout strategies are presented to achieve relatively small and deterministic network-introduced latencies and reduce data loss rates. These are effective in providing better network performance without performance degradation of other services. After the investigation into the layout strategies, the thesis presents a new transport protocol which is more effcient than UDP and TCP for guaranteeing reliable and time-critical communications in WNCSs. From the networking perspective, introducing appropriate communication schemes, modifying existing network protocols and devising new protocols, have been the most effective and popular ways to improve or even guarantee real-time performance to a certain extent. Most previously proposed schemes and protocols were designed for real-time multimedia communication and they are not suitable for real-time control systems. Therefore, devising a new network protocol that is able to satisfy real-time requirements in WNCSs is the main objective of this research project. The Conditional Retransmission Enabled Transport Protocol (CRETP) is a new network protocol presented in this thesis. Retransmitting unacknowledged data packets is effective in compensating for data losses. However, every data packet in realtime control systems has a deadline and data is assumed invalid or even harmful when its deadline expires. CRETP performs data retransmission only in the case that data is still valid, which guarantees data timeliness and saves memory and network resources. A trade-off between delivery reliability, transmission latency and network resources can be achieved by the conditional retransmission mechanism. Evaluation of protocol performance was conducted through extensive simulations. Comparative studies between CRETP, UDP and TCP were also performed. These results showed that CRETP significantly: 1). improved reliability of communication, 2). guaranteed validity of received data, 3). reduced transmission latency to an acceptable value, and 4). made delays relatively deterministic and predictable. Furthermore, CRETP achieved the best overall performance in comparative studies which makes it the most suitable transport protocol among the three for real-time communications in a WNCS.

22

Chen, Shi. "An energy-efficient media access control protocol for wireless sensor networks /". View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?COMP%202006%20CHEN.

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23

Larsen, Timothy Scott. "Studying the Performance of Wireless Mesh Networks Using the HxH Transport Control Protocol". Diss., CLICK HERE for online access, 2010. http://contentdm.lib.byu.edu/ETD/image/etd3375.pdf.

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24

Shen, Ji. "Efficient 3G multimedia communication control protocol (H.245) and implementations /". access full-text access abstract and table of contents, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?mphil-cs-b19886093a.pdf.

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Abstract (sommario):

Thesis (M.Phil.)--City University of Hong Kong, 2005.
"Submitted to Department of Computer Science in partial fulfillment of the requirements for the degree of Master of Philosophy" Includes bibliographical references (leaves 110-112)

25

Alazemi, Hamed M. K. "Modeling and analysis of stochastic self-similar processes and TCP/IP congestion control in high-speed computer communication networks /". Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/6000.

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26

Shah, Niravkumar. "Efficient medium access control protocol for vehicular ad-hoc networks". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2012. https://ro.ecu.edu.au/theses/495.

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Intelligent transportation systems (ITS) have enjoyed a tremendous growth in the last decade and the advancement in communication technologies has played a big role behind the success of ITS. Inter-vehicle communication (IVC) is a critical requirement for ITS and due to the nature of communication, vehicular ad-hoc network technology (VANET) is the most suitable communication technology for inter-vehicle communications. In Practice, however, VANET poses some extreme challenges including dropping out of connections as the moving vehicle moves out of the coverage range, joining of new nodes moving at high speeds, dynamic change in topology and connectivity, time variability of signal strength, throughput and time delay. One of the most challenging issues facing vehicular networks lies in the design of efficient resource management schemes, due to the mobile nature of nodes, delay constraints for safety applications and interference. The main application of VANET in ITS lies in the exchange of safety messages between nodes. Moreover, as the wireless access in vehicular environment (WAVE) moves closer to reality, management of these networks is of increasing concern for ITS designers and other stakeholder groups. As such, management of resources plays a significant role in VANET and ITS. For resource management in VANET, a medium access control protocol is used, which makes sure that limited resources are distributed efficiently. In this thesis, an efficient Multichannel Cognitive MAC (MCM) is developed, which assesses the quality of channel prior to transmission. MCM employs dynamic channel allocation and negotiation algorithms to achieve a significant improvement in channel utilisation, system reliability, and delay constraints while simultaneously addressing Quality of Service. Moreover, modified access priority parameters and safety message acknowledgments will be used to improve the reliability of safety messages. The proposed protocols are implemented using network simulation tools. Extensive experiments demonstrated a faster and more efficient reception of safety messages compared to existing VANET technologies. Finally, improvements in delay and packet delivery ratios are presented.

27

Biswas, Md Israfil. "Internet congestion control for variable-rate TCP traffic". Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=182264.

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The Transmission Control Protocol (TCP) has been designed for reliable data transport over the Internet. The performance of TCP is strongly influenced by its congestion control algorithms that limit the amount of traffic a sender can transmit based on end-to-end available capacity estimations. These algorithms proved successful in environments where applications rate requirements can be easily anticipated, as is the case for traditional bulk data transfer or interactive applications. However, an important new class of Internet applications has emerged that exhibit significant variations of transmission rate over time. Variable-rate traffic poses a new challenge for congestion control, especially for applications that need to share the limited capacity of a bottleneck over a long delay Internet path (e.g., paths that include satellite links). This thesis first analyses TCP performance of bursty applications that do not send data continuously, but generate data in bursts separated by periods in which little or no data is sent. Simulation analysis shows that standard TCP methods do not provide efficient support for bursty applications that produce variable-rate traffic, especially over long delay paths. Although alternative forms of congestion control like TCP-Friendly Rate Control and the Datagram Congestion Control Protocol have been proposed, they did not achieve widespread deployment. Therefore many current applications that rely upon User Datagram Protocol are not congestion controlled. The use of non-standard or proprietary methods decreases the effectiveness of Internet congestion control and poses a threat to the Internet stability. Solutions are therefore needed to allow bursty applications to use TCP. Chapter three evaluates Congestion Window Validation (CWV), an IETF experimental specification that was proposed to improve support for bursty applications over TCP. It concluded that CWV is too conservative to support many bursty applications and does not provide an incentive to encourage use by application designers. Instead, application designers often avoid generating variable-rate traffic by padding idle periods, which has been shown to waste network resources. CWV is therefore shown to not provide an acceptable solution for variable-rate traffic. In response to this shortfall, a new modification to TCP, TCP-JAGO, is proposed. This allows variable-rate traffic to restart quickly after an inactive (i.e., idle) period and to effectively utilise available network resources while sending at a lower rate than the available rate (i.e., during an application-limited period). The analysis in Chapter five shows that JAGO provides faster convergence to a steady-state rate and improves throughput by more efficiently utilising the network. TCP-JAGO is also shown to provide an appropriate response when congestion is experienced after restart. Variable-rate TCP traffic can also be impacted by the Initial Window algorithm at the start or during the restart of a session. Chapter six considers this problem, where TCP has no prior indication of the network state. A recent proposal for a larger initial window is analysed. Issues and advantages of using a large IW over a range of scenarios are discussed. The thesis concludes by presenting recommendations to improve TCP support for bursty applications. This also provides an incentive for application designers to choose TCP for variable-rate traffic.

28

Olsén, Jörgen. "Stochastic modeling and simulation of the TCP protocol /". Uppsala : Matematiska institutionen, Univ. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3534.

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29

Scofield, Dan. "Hop-by-hop transport control for multi-hop wireless networks /". Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1812.pdf.

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30

Morrison, Charles Michael. "An investigation of network efficiency and control protocol issues for a configurable collaboration support system". Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185931.

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Abstract (sommario):

Increased global competition is fueling a movement towards semi-autonomous or "self-managing" business teams. At the same time, the ability to interconnect computers has provided a technological base for increased computer support of business teams. A flexible system should accommodate a wide variety of group and task characteristics in both face-to-face and geographically-dispersed environments. An architecture for a system named TEAMWORK is developed that provides flexible support for business teams. System functions are organized into six configurable components, audio processing, video processing, text processing, graphic processing, data management, and numeric processing, collectively addressing a wide spectrum of group tasks. TeamWriter is highly configurable text processing tool implemented to represent and partially evaluate one aspect of TEAMWORK's architecture. Pulldown menus and picture buttons allow access functions. Support for a wide variety of team access protocols, real- and non-real-time work styles, multi-user document writing, brainstorming, idea consolidation, visual group dynamics, and more is included. Document changes appended to a centrally located server file maintain a linear revision history. Evaluation session indicated participants especially liked TeamWriter's multiuser document writing capabilities, picture buttons, authorship provisions, and multiple configurations. Suggestions for enhancing brainstorming and idea consolidation capabilities are supported by the underlying set of configurable functions and involve adding new interface configurations. Sessions also demonstrated that field testing will be needed to thoroughly evaluate TeamWriter; participants were unable to explore all of TeamWriter's features in the one and a half hour long evaluation sessions. Research contributions include a comprehensive team collaboration support system architecture, an implemented configurable text processing module suited for further evaluation, implementation methods, and insight into the functional requirements of a team collaboration support system. Future research directions include field testing TeamWriter, implementing and evaluating the numeric processing module, and investigating non-hierarchical, iconic interfaces to TeamWriter section. As audio, video, and high speed LAN technology become available, prototypes investigating design and implementation strategies for audio, video, and graphic modules will be built.

31

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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Abstract (sommario):

Orientador: Nelson Luis Saldanha da Fonseca
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação
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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

32

Miller, Alan Henry David. "Best effort measurement based congestion control". Thesis, Connect to e-thesis, 2001. http://theses.gla.ac.uk/1015/.

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Thesis (Ph.D.) -- University of Glasgow, 2001.
Includes bibliographical references (p.i-xv). Print version also available. Mode of access : World Wide Web. System requirments : Adobe Acrobat reader reuired to view PDF document.

33

Reddy, Pavan K. "Implementation of an available bit rate service for satellite IP networks using a performance enhancing proxy". Link to electronic thesis, 2004. http://www.wpi.edu/Pubs/ETD/Available/etd-0429104-100149/.

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34

Xiao, Chunpeng. "Advanced link and transport control protocols for broadband optical access networks". Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-11082006-183908/.

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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2007.
Chang, Gee-Kung, Committee Chair ; Zhou, G.Tong, Committee Member ; Copeland, John, Committee Member ; Riley, George, Committee Member ; Ingram, Mary Ann, Committee Member ; Ammar, Mostafa, Committee Member.

35

Allman, Mark. "Improving TCP performance over satellite channels". Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177615641.

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36

Jero, Samuel C. "Performance Analysis of the Datagram Congestion Control Protocol DCCP for Real-Time Streaming Media Applications". Ohio University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1374854584.

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37

Nandwani, Mukta. "Real-time Remote Visualization of Scientific Data". Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/33138.

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Visualization of large amounts of simulation data is important for the understanding of most physical phenomena. The limited capabilities of desktop machines make them unsuitable for handling excessive amounts of simulation data. The present day high speed networks have made it possible to remotely visualize the data being generated by a supercomputer in real time. In order for such a system to be reliable, a robust communication protocol and an efficient compression mechanism are needed. This work presents a remote visualization system that addresses these issues, and emphasizes the design and implementation of the application level network protocol. A control theory based adaptive rate control algorithm is presented for UDP streams that maximizes the effective throughout experienced by the stream while minimizing the packet loss. The algorithm is shown to make the system responsive to changing network conditions. This makes the system deployable over any network, including the Internet.
Master of Science

38

Hirayama, Yasuhiro, Hiraku Okada, Takaya Yamazato e Masaaki Katayama. "An Access Control Protocol based on Estimation of Multimedia Trafic with an Adpative Algorithm in CDMA Packet Network". IEEE, 2002. http://hdl.handle.net/2237/7808.

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39

Augustin, Angelika. "Effective Power Consumption in MAC Protocols for Wireless Sensor Networks". Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-286.

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Wireless sensor networks offer easy implementation, flexibility and mobility of hand held

devices. Sensors consist of an internal power source, which is the great limitation for

the life time and the usage of sensor networks. To increase the life time, sensors should

stay in energy saving sleep mode as long as possible, because in sleep mode the radio is

either shut down or working with less energy. Better energy handling is implemented in

different power saving mechanism of common Medium Access Control protocols, which are

evaluated and analyzed and further extensions and ideas to improve the energy efficiency

are presented. Slotted PSM is simulated with the NS2 and compared to the WLAN 802.11

PSM technology and the results show that energy efficiency and power consumption are

much better implemented and life time increases with the use of Slotted PSM.

40

Lima, Michele Mara de Araujo Espindula. "Projeto de controladores otimos para gerenciamento ativo de filas". [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276334.

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Orientador: Nelson Luis Saldanha da Fonseca
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação
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Resumo: A ocorrência de congestionamento degrada o desempenho das redes de computadores. Dentre as conseqüências negativas da sua ocorrência cita-se a diminuição da vazão, a perda de pacotes, e o aumento do atraso. Para prevenir e controlar o congestionamento, o protocolo Transmission Control Protocol (TCP) varia a taxa de transmissão de dados de acordo com o nível de congestionamento existente. As políticas de Gerenciamento Ativo de Filas, do Inglês Active Queue Management (AQM), monitoram o nível de ocupação das filas, afim de notificar o congestionamento incipiente aos nós emissores. Esta notificação é realizada através da marca¸c¿ao ou do descarte de pacotes. O sistema de controle de congestionamento em redes TCP/IP, pode ser visto como um sistema de controle por retroalimentação, no qual, a taxa de transmissão dos n'os fontes é ajustada de acordo com o nível de ocupação da fila. Os controladores para o gerenciamento ativo de filas determinam o valor da probabilidade de descarte ou de marcação, buscando a maximização da vazão e a minimiza¸c¿ao das perdas, garantindo, assim, a estabilidade do tamanho da fila independentemente das variações das condições da rede. Nesta tese, são utilizadas técnicas da teoria de controle ótimo para definir uma política ótima de gerenciamento ativo de filas, denominada H2-AQM. A principal característica da H2-AQM é o uso de controladores não racionais, superando-se, assim, a dificuldade de se incorporar no projeto do controlador a garantia de estabilidade em relação ao atraso da retroalimentação. Outrossim, a estabilidade e os objetivos de desempenho do sistema são completamente 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 operando no mesmo ponto de equilíbrio definem diferentes caminhos entre um ponto qualquer de operação do sistema e o ponto de equilíbrio. Por outro lado, o caminho percorrido para atingir a estabilidade depende dos objetivos usados para projetar o controlador. Nesta tese, é discutida, também, a escolha dos objetivos do projeto de um controlador ótimo para o gerenciamento ativo de filas. Os desempenhos dos diferentes controladores são avaliados e a eficácia do controlador que apresentou o melhor desempenho foi comparado com o desempenho das políticas RED e PI-AQM
Abstract: Congestion is one of the most significant problems in networking. When congestion occurs, the network performance degrades, leading to throughput decrease, delay increase and packet losses. In order to avoid congestion the Transmission Control Protocol (TCP) changes its transmission rate according to the level of congestion. AQM policies notify incipient congestion to TCP source by marking or dropping packets. In TCP/ICP networks, congestion control system can be viewed as a feedback control system in which the transmission rate of the sources are adjusted according to the level of congestion inferred by the queue occupancy. Controllers are responsible for determining the appropriate value of the dropping/marking probability values that stabilizes the queue size regardless of the network condition. In this thesis, optimal control theory is used to conceive an optimal AQM policy, called H2-AQM. The novelty of the proposed approach lies in the use of non-rational controllers that overcomes the difficulty of incorporating guarantees of the stability with respect to the delayed part of the system in the controller design. 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 define different pathes for taking the system state to a target point of equilibrium. Moreover, the path depends on the objectives established for the design of the controller. In this thesis, a discussion on the design of AQM optimal controllers for optimal performance is also presented. The performance produced by different optimal controllers was investigated. The efficacy of the controller which presented the best performance was, then, compared to the performance of both RED and PI-AQM policies
Doutorado
Redes de Computadores
Doutor em Ciência da Computação

41

Augusto, Leonardo Rangel. "Controladores otimos para gerenciamento ativo de filas na arquitetura de serviços diferenciados da Internet". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276179.

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Orientador: Nelson Luis Saldanha da Fonseca
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação
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Resumo: A classe de Serviço Assegurado da arquitetura de Serviços Diferenciados (DiffServ) da Internet inclui a provisão de diferenciação de banda passante, o que depende do adequado USG de mecanismos de condicionamento de tráfego e gerenciamento ativo de filas (AQM). Nesta dissertação, propõe-se um controlador ótimo para gerenciamento ativo de filas para a arquitetura Diffserv. Seu projeto considera intrinsecamente a influência de fluxos não adaptativos na dinâmica do controle de congestionamento. Apesar de o controlador obtido ser racional, seu projeto utiliza uma abordagem não-racional, o que aumenta a precisão do modelo. Simulações conduzidas demonstram que o controlador proposto reduz o descarte desnecessário de pacotes, aumentando o goodput e diminuindo a quantidade de RTOs dos emissores TCP.
Abstract: The Assured Service of Differentiated Services Arehitecture (DiffServ) is currently used for providing throughput differentiation in the Internet. For this, traffic policing and active queue management (AQM) mechanisms must be used. In this dissertation, we use a non-rational approach to develop an optimal AQM controller. Its design considers both adaptative and non-adaptative like UDP. Simulations were conducted for comparison with other proposals. Results show that the proposed controller reduces unnecessary packet drops, increases the goodput and reduces the TCP sender's Retransmission Timeouts.
Mestrado
Redes de Computadores
Mestre em Ciência da Computação

42

Hurtig, Per. "Improving the Timeliness of SCTP Message Transfers". Licentiate thesis, Karlstad : Faculty of Economic Sciences, Communication and IT, Computer Science, Karlstads universitet, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-2861.

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43

Irwin, Barry Vivian William. "A framework for the application of network telescope sensors in a global IP network". Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1004835.

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The use of Network Telescope systems has become increasingly popular amongst security researchers in recent years. This study provides a framework for the utilisation of this data. The research is based on a primary dataset of 40 million events spanning 50 months collected using a small (/24) passive network telescope located in African IP space. This research presents a number of differing ways in which the data can be analysed ranging from low level protocol based analysis to higher level analysis at the geopolitical and network topology level. Anomalous traffic and illustrative anecdotes are explored in detail and highlighted. A discussion relating to bogon traffic observed is also presented. Two novel visualisation tools are presented, which were developed to aid in the analysis of large network telescope datasets. The first is a three-dimensional visualisation tool which allows for live, near-realtime analysis, and the second is a two-dimensional fractal based plotting scheme which allows for plots of the entire IPv4 address space to be produced, and manipulated. Using the techniques and tools developed for the analysis of this dataset, a detailed analysis of traffic recorded as destined for port 445/tcp is presented. This includes the evaluation of traffic surrounding the outbreak of the Conficker worm in November 2008. A number of metrics relating to the description and quantification of network telescope configuration and the resultant traffic captures are described, the use of which it is hoped will facilitate greater and easier collaboration among researchers utilising this network security technology. The research concludes with suggestions relating to other applications of the data and intelligence that can be extracted from network telescopes, and their use as part of an organisation’s integrated network security systems

44

Olsén, Jörgen. "Stochastic Modeling and Simulation of the TCP protocol". Doctoral thesis, Uppsala University, Mathematical Statistics, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3534.

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The success of the current Internet relies to a large extent on a cooperation between the users and the network. The network signals its current state to the users by marking or dropping packets. The users then strive to maximize the sending rate without causing network congestion. To achieve this, the users implement a flow-control algorithm that controls the rate at which data packets are sent into the Internet. More specifically, the Transmission Control Protocol (TCP) is used by the users to adjust the sending rate in response to changing network conditions. TCP uses the observation of packet loss events and estimates of the round trip time (RTT) to adjust its sending rate.

In this thesis we investigate and propose stochastic models for TCP. The models are used to estimate network performance like throughput, link utilization, and packet loss rate. The first part of the thesis introduces the TCP protocol and contains an extensive TCP modeling survey that summarizes the most important TCP modeling work. Reviewed models are categorized as renewal theory models, fixed-point methods, fluid models, processor sharing models or control theoretic models. The merits of respective category is discussed and guidelines for which framework to use for future TCP modeling is given.

The second part of the thesis contains six papers on TCP modeling. Within the renewal theory framework we propose single source TCP-Tahoe and TCP-NewReno models. We investigate the performance of these protocols in both a DropTail and a RED queuing environment. The aspects of TCP performance that are inherently depending on the actual implementation of the flow-control algorithm are singled out from what depends on the queuing environment.

Using the fixed-point framework, we propose models that estimate packet loss rate and link utilization for a network with multiple TCP-Vegas, TCP-SACK and TCP-Reno on/off sources. The TCP-Vegas model is novel and is the first model capable of estimating the network's operating point for TCP-Vegas sources sending on/off traffic. All TCP and network models in the contributed research papers are validated via simulations with the network simulator ns-2.

This thesis serves both as an introduction to TCP and as an extensive orientation about state of the art stochastic TCP models.

45

Morgan, Jon, e Charles H. Jones. "PCM Backfill: Providing PCM to the Control Room Without Dropouts". International Foundation for Telemetering, 2014. http://hdl.handle.net/10150/577490.

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ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA
One of the initial control room capabilities to be demonstrated by iNET program is the ability to provide data displays in the control room that do not contain data dropouts. This concept is called PCM Backfill where PCM data is both transmitted via traditional SST and recorded onboard via an iNET compatible recorder. When data dropouts occur, data requests are made over the telemetry network to the recorder for the missing portions of the PCM data stream. The retrieved data is sent over the telemetry network to the backfill application and ultimately delivered to a pristine data display. The integration of traditional SST and the PCM Backfill capability provides both real-time safety of flight data side-by-side with pristine data suitable for advanced analysis.

46

Amoah, Raphael. "Formal security analysis of the DNP3-Secure Authentication Protocol". Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/93798/1/Raphael_Amoah_Thesis.pdf.

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This thesis evaluates the security of Supervisory Control and Data Acquisition (SCADA) systems, which are one of the key foundations of many critical infrastructures. Specifically, it examines one of the standardised SCADA protocols called the Distributed Network Protocol Version 3, which attempts to provide a security mechanism to ensure that messages transmitted between devices, are adequately secured from rogue applications. To achieve this, the thesis applies formal methods from theoretical computer science to formally analyse the correctness of the protocol.

47

Gautam, S. Vijay. "Performance Analysis Of A Variation Of The Distributed Queueing Access Protocol". Thesis, Indian Institute of Science, 1995. https://etd.iisc.ac.in/handle/2005/149.

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"A distributed queueing Medium Access Control (MAC) protocol is used in Distributed Queue Dual Bus (DQDB) networks. A modified version of the MAC protocol was proposed by R.R. Pillai and U. Mukherji in an attempt to overcome some of the shortcomings of the DQDB MAC protocol. They analyzed the performance of the system for Bernoulli arrivals and for large propagation delays between the nodes. We extend the performance analysis of the modified MAC protocol for a DQDB type of Network. The parameter of interest to us is the bus access delay. This has two components, viz., the request bus access delay and the data bu6 access delay. We use the model at the request point at node and present methods to evaluate the delay experienced in such a model. The model is an n-priority ./D/l queue with D vacations (non-preemptive priority) where n is the number of nodes sending requests on the request bus for transmission on the data bus. The methods presented help to evaluate the request bus access delay when the arrivals at each node are Markovian Arrival Processes (MAPs). The algorithms for evaluating the mean request bus access delay are based on matrix geometric techniques. Thus, one can use the algorithms developed in the literature to solve for the finite buffers case too. This model, for the request bus access delay, holds irrespective of the propagation delay between the nodes. We also evaluate the inter-departure time of class 1 customers and virtual customers in a 2-priority M/G/l system with G vacations (non-preemptive priority). In the case of Poisson arrivals at all the nodes, we would have a 2-priority M/D/l system with D vacations (non-preemptive priority). We thus evaluate the inter-arrival time of the free slots on the data bus as seen by Node 2. Note that this is independent of the number of active nodes in the network We then develop methods to evaluate the mean data bus access delay experienced by the customers at Node 2 in a three-node network with 2 nodes communicating with the third when the propagation delay between the nodes is large. We consider the case of finite Local Queue buffers at the two nodes. Using this assumption we arrive at process of arrivals to the Combined Queue and the process of free slots on the data bus to be Markov Modulated Bernoulli processes. The model at the combined queue at Node 2 then has a Quasi Birth-Death evolution. Thus, this system is solved by using the Ramaswami-Latouche algorithm. The stationary probabilities are then used to evaluate the mean data bus access delay experienced at Node 2. The finite buffer case of this system can be solved by G.Wi Stewart's algorithm. The method in modelling the system and the results are presented in detail for Poisson arrivals. The extension of this to more complex processes is also explained. We encounter in the analysis an explosion of the state-space of the system. We try to counter this by considering approximations to the process of free slots on the data bus. The approximations considered are on the basis of what are known as Idealized Aggregates. The performance of the approximation is also detailed. It works very well under low and moderate load but underestimates the mean delay under heavy load. Thereafter, we discuss the performance of the system with reference to the mean of the access delay and the standard deviation of the access delay under varying traffic at the two nodes. For this part we use simulation results to discuss the performance. The comparison between the performance measures at both the nodes is also done. Then we develop methods/techniques to understand the performance of the system when we have finite propagation delays between the nodes. We concentrate on the 3-node problem and calculate performance bounds based on linear programs. This is illustrated in detail for Bernoulli arrivals for the case of 1 slot propagation delay between the nodes as well as for the case of 2 slots propagation delay. The performance of the bounds obtained is also detailed. The presence of an idling system at the combined queue of Node 2 makes the bounds somewhat loose. Finally, we discuss the performance of the system with reference to the mean access delay and the standard deviation of the access delay under varying load on the system. Again, we rely on simulation studies. Finally, we study the performance of the system as a multiplexer. For this, we restrict the traffic to Markov Modulated Processes (or those which would satisfy the Gartner-Ellis Theorem requirements). The traffic is characterized by what are known as Envelope Processes - Lower and Upper. The class of processes which satisfy the conditions of the Gartner-Ellis theorem come under the category where both the Envelope Processes exist and the Minimum Envelope Rate and the Maximum Lower Envelope Rate are the same. We use the system evolution equations at the combined queue at any node to develop relations between the various input and output processes. First, this is done for a. system of this kind, in isolation. Then, we consider this system as a part of the modified protocol and present relations, among the various input and output processes, which are specific to the modified protocol. The possible use of all of the above to do Admission Control at the entry point to the Asynchronous Transfer Mode (ATM) network is also presented.

48

Gautam, S. Vijay. "Performance Analysis Of A Variation Of The Distributed Queueing Access Protocol". Thesis, Indian Institute of Science, 1995. http://hdl.handle.net/2005/149.

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"A distributed queueing Medium Access Control (MAC) protocol is used in Distributed Queue Dual Bus (DQDB) networks. A modified version of the MAC protocol was proposed by R.R. Pillai and U. Mukherji in an attempt to overcome some of the shortcomings of the DQDB MAC protocol. They analyzed the performance of the system for Bernoulli arrivals and for large propagation delays between the nodes. We extend the performance analysis of the modified MAC protocol for a DQDB type of Network. The parameter of interest to us is the bus access delay. This has two components, viz., the request bus access delay and the data bu6 access delay. We use the model at the request point at node and present methods to evaluate the delay experienced in such a model. The model is an n-priority ./D/l queue with D vacations (non-preemptive priority) where n is the number of nodes sending requests on the request bus for transmission on the data bus. The methods presented help to evaluate the request bus access delay when the arrivals at each node are Markovian Arrival Processes (MAPs). The algorithms for evaluating the mean request bus access delay are based on matrix geometric techniques. Thus, one can use the algorithms developed in the literature to solve for the finite buffers case too. This model, for the request bus access delay, holds irrespective of the propagation delay between the nodes. We also evaluate the inter-departure time of class 1 customers and virtual customers in a 2-priority M/G/l system with G vacations (non-preemptive priority). In the case of Poisson arrivals at all the nodes, we would have a 2-priority M/D/l system with D vacations (non-preemptive priority). We thus evaluate the inter-arrival time of the free slots on the data bus as seen by Node 2. Note that this is independent of the number of active nodes in the network We then develop methods to evaluate the mean data bus access delay experienced by the customers at Node 2 in a three-node network with 2 nodes communicating with the third when the propagation delay between the nodes is large. We consider the case of finite Local Queue buffers at the two nodes. Using this assumption we arrive at process of arrivals to the Combined Queue and the process of free slots on the data bus to be Markov Modulated Bernoulli processes. The model at the combined queue at Node 2 then has a Quasi Birth-Death evolution. Thus, this system is solved by using the Ramaswami-Latouche algorithm. The stationary probabilities are then used to evaluate the mean data bus access delay experienced at Node 2. The finite buffer case of this system can be solved by G.Wi Stewart's algorithm. The method in modelling the system and the results are presented in detail for Poisson arrivals. The extension of this to more complex processes is also explained. We encounter in the analysis an explosion of the state-space of the system. We try to counter this by considering approximations to the process of free slots on the data bus. The approximations considered are on the basis of what are known as Idealized Aggregates. The performance of the approximation is also detailed. It works very well under low and moderate load but underestimates the mean delay under heavy load. Thereafter, we discuss the performance of the system with reference to the mean of the access delay and the standard deviation of the access delay under varying traffic at the two nodes. For this part we use simulation results to discuss the performance. The comparison between the performance measures at both the nodes is also done. Then we develop methods/techniques to understand the performance of the system when we have finite propagation delays between the nodes. We concentrate on the 3-node problem and calculate performance bounds based on linear programs. This is illustrated in detail for Bernoulli arrivals for the case of 1 slot propagation delay between the nodes as well as for the case of 2 slots propagation delay. The performance of the bounds obtained is also detailed. The presence of an idling system at the combined queue of Node 2 makes the bounds somewhat loose. Finally, we discuss the performance of the system with reference to the mean access delay and the standard deviation of the access delay under varying load on the system. Again, we rely on simulation studies. Finally, we study the performance of the system as a multiplexer. For this, we restrict the traffic to Markov Modulated Processes (or those which would satisfy the Gartner-Ellis Theorem requirements). The traffic is characterized by what are known as Envelope Processes - Lower and Upper. The class of processes which satisfy the conditions of the Gartner-Ellis theorem come under the category where both the Envelope Processes exist and the Minimum Envelope Rate and the Maximum Lower Envelope Rate are the same. We use the system evolution equations at the combined queue at any node to develop relations between the various input and output processes. First, this is done for a. system of this kind, in isolation. Then, we consider this system as a part of the modified protocol and present relations, among the various input and output processes, which are specific to the modified protocol. The possible use of all of the above to do Admission Control at the entry point to the Asynchronous Transfer Mode (ATM) network is also presented.

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Ben, Ameur Chiheb. "TCP Protocol Optimization for HTTP Adaptive Streaming". Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S127/document.

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Abstract (sommario):

Le streaming adaptatif sur HTTP, désigné par HAS, est une technique de streaming vidéo largement déployée sur Internet. Elle utilise TCP comme protocole de transport. Elle consiste à segmenter la vidéo stockée sur un serveur web en petits segments indépendants de même durée de lecture et transcodés à plusieurs niveaux de qualité, désignés par "chunks". Le player, du côté du client HAS, demande périodiquement un nouveau chunk. Il sélectionne le niveau de qualité en se basant sur l’estimation de la bande passante du/des chunk(s) précédent(s). Étant donné que chaque client HAS est situé au sein d’un réseau d’accès, notre étude traite un cas fréquent dans l’usage quotidien: lorsque plusieurs clients partagent le même lien présentant un goulot d’étrangement et se trouvent en compétition sur la bande passante. Dans ce cas, on signale une dégradation de la qualité d’expérience (QoE) des utilisateurs de HAS et de la qualité de service (QoS) du réseau d’accès. Ainsi, l’objectif de cette thèse est d’optimiser le protocole TCP pour résoudre ces dégradations de QoE et QoS. Notre première contribution propose une méthode de bridage du débit HAS au niveau de la passerelle. Cette méthode est désignée par "Receive Window Tuning Method" (RWTM): elle utilise le principe de contrôle de flux de TCP et l’estimation passive du RTT au niveau de la passerelle. Nous avons comparé les performances de RWTM avec une méthode récente implémentée à la passerelle qui utilise une discipline particulière de gestion de la file d’attente, qui est désignée par "Hierarchical Token Bucket shaping Method" (HTBM). Les résultats d’évaluations indiquent que RWTM offre une meilleure QoE et une meilleure QoS de réseau d’accès que HTBM. Notre deuxième contribution consiste à mener une étude comparative combinant deux méthodes de bridages, RWTM et HTBM, avec quatre variantes TCP largement déployées, NewReno, Vegas, Illinois et Cubic. Les résultats d'évaluations montrent une discordance importante entre les performances des différentes combinaisons. De plus, la combinaison qui améliore les performances dans la majorité des scénarios étudiés est celle de RWTM avec Illinois. En outre, une mise à jour efficace de la valeur du paramètre "Slow Start Threshold", sthresh, peut accélérer la vitesse de convergence du player vers la qualité optimale. Notre troisième contribution propose une nouvelle variante de TCP adaptée aux flux HAS, qu’on désigne par TcpHas; c’est un algorithme de contrôle de congestion de TCP adapté aux spécifications de HAS. TcpHas estime le niveau de la qualité optimale du flux HAS en se basant sur l’estimation de la bande passante de bout en bout. Ensuite, TcpHas applique un bridage au trafic HAS en fonction du débit d’encodage du niveau de qualité estimé. TcpHas met à jour ssthresh pour accélérer la vitesse de convergence. Une étude comparative a été réalisée avec la variante Westwood+. Les résultats d’évaluations montrent que TcpHas est plus performant que Westwood+
HTTP adaptive streaming (HAS) is a streaming video technique widely used over the Internet. It employs Transmission Control Protocol (TCP) as transport protocol and it splits the original video inside the server into segments of same duration, called "chunks", that are transcoded into multiple quality levels. The HAS player, on the client side, requests for one chunk each chunk duration and it commonly selects the quality level based on the estimated bandwidth of the previous chunk(s). Given that the HAS clients are located inside access networks, our investigation involves several HAS clients sharing the same bottleneck link and competing for bandwidth. Here, a degradation of both Quality of Experience (QoE) of HAS users and Quality of Service (QoS) of the access network are often recorded. The objective of this thesis is to optimize the TCP protocol in order to solve both QoE and QoS degradations. Our first contribution consists of proposing a gateway-based shaping method, that we called Receive Window Tuning Method (RWTM); it employs the TCP flow control and passive round trip time estimation on the gateway side. We compared the performances of RWTM with another gateway-based shaping method that is based on queuing discipline, called Hierarchical Token Bucket shaping Method (HTBM). The results of evaluation indicate that RWTM outperforms HTBM not only in terms of QoE of HAS but also in terms of QoS of access network by reducing the queuing delay and significantly reducing packet drop rate at the bottleneck.Our second contribution consists of a comparative evaluation when combining two shaping methods, RWTM and HTBM, and four very common TCP variants, NewReno, Vegas, Illinois and Cubic. The results show that there is a significant discordance in performance between combinations. Furthermore, the best combination that improves performances in the majority of scenarios is when combining Illinois variant with RWTM. In addition, the results reveal the importance of an efficient updating of the slow start threshold value, ssthresh, to accelerate the convergence toward the best feasible quality level. Our third contribution consists of proposing a novel HAS-based TCP variant, that we called TcpHas; it is a TCP congestion control algorithm that takes into consideration the specifications of HAS flow. Besides, it estimates the optimal quality level of its corresponding HAS flow based on end-to-end bandwidth estimation. Then, it permanently performs HAS traffic shaping based on the encoding rate of the estimated level. It also updates ssthresh to accelerate convergence speed. A comparative performance evaluation of TcpHas with a recent and well-known TCP variant that employs adaptive decrease mechanism, called Westwood+, was performed. Results indicated that TcpHas largely outperforms Westwood+; it offers better quality level stability on the optimal quality level, it dramatically reduces the packet drop rate and it generates lower queuing delay

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Arumaithurai, Mayutan [Verfasser], Xiaoming [Akademischer Betreuer] Fu, K. K. [Akademischer Betreuer] Ramakrishnan e Dieter [Akademischer Betreuer] Hogrefe. "Network Friendly Congestion Control: Framework, Protocol Design and Evaluation / Mayutan Arumaithurai. Gutachter: Xiaoming Fu ; K. K. Ramakrishnan ; Dieter Hogrefe. Betreuer: Xiaoming Fu". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2010. http://d-nb.info/1043029532/34.

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