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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Studies on performance aspects of smart wireless devices and related network services

Unknown Date (has links)
This study is a focused effort on elucidating the performance aspects of modern, handheld wireless devices and associated mobile network services. Specifically addressed thereof are: (i) Assessing the performance details on certain hardware sections of smart handheld devices and (ii) determining the performance profile of market penetration considerations vis-à-vis provisioning mobile networks. To meet the scope of this research, the projected efforts are exercised in compiling relevant literature and deciding the said hardware and technoeconomic performance issues. Hence, written in two parts, Part A is devoted to hardware performance details of smart, handheld devices relevant to (a) delay issues in PCB layouts; (b) crosstalk problems at the baseband level (audio/multimedia) using EMI concepts and (c) ascertaining non-catastrophic EMP/EMI effects at the RF-sections so as to implement protection strategies via compensating networks. Part B is concerned with the technoeconomics of wireless networks in supporting mobile (handheld devices). Correspondingly, two market related considerations versus service performance details are considered. The first one refers to deducing a relative performance index that includes technology (mobile speed) details plus economics profiles of the users in the service area. The second task refers to elucidating a performance index of such services in terms of hedonic pricing heuristics. The theoretical aspects of the test studies as above are supplemented with experimental and/or simulation details as appropriate. Hence, the efficacy of performance details are discussed in real-world applications. Lastly, possible research items for future studies are identified as open-questions. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection
62

Efficient tracking of significant communication patterns in computer networks. / CUHK electronic theses & dissertations collection

January 2011 (has links)
Shi, Xingang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 135-152). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
63

A study of the effects of TCP designs on server efficiency and throughputs on wired and wireless networks.

January 2003 (has links)
Yeung, Fei-Fei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 144-146). / Abstracts in English and Chinese. / Introduction --- p.1 / Chapter Part I: --- A New Socket API for Enhancing Server Efficiency --- p.5 / Chapter Chapter 1 --- Introduction --- p.6 / Chapter 1.1 --- Brief Background --- p.6 / Chapter 1.2 --- Deficiencies of Nagle's Algorithm and Goals and Objectives of this Research --- p.7 / Chapter 1.2.1 --- Effectiveness of Nagle's Algorithm --- p.7 / Chapter 1.2.2 --- Preventing Small Packets via Application Layer --- p.9 / Chapter 1.2.3 --- Minimum Delay in TCP Buffer --- p.10 / Chapter 1.2.4 --- Maximum Delay in TCP Buffer --- p.11 / Chapter 1.2.5 --- New Socket API --- p.12 / Chapter 1.3 --- Scope of Research and Summary of Contributions --- p.12 / Chapter 1.4 --- Organization of Part 1 --- p.13 / Chapter Chapter 2 --- Background --- p.14 / Chapter 2.1 --- Review of Nagle's Algorithm --- p.14 / Chapter 2.2 --- Additional Problems Inherent in Nagle's Algorithm --- p.17 / Chapter 2.3 --- Previous Proposed Modifications on Nagle's Algorithm --- p.22 / Chapter 2.3.1 --- The Minshall Modification --- p.22 / Chapter 2.3.1.1 --- The Minshall Modification --- p.22 / Chapter 2.3.1.2 --- The Minshall et al. Modification --- p.23 / Chapter 2.3.2 --- The Borman Modification --- p.23 / Chapter 2.3.3 --- The Jeffrey et al. Modification --- p.25 / Chapter 2.3.3.1 --- The EOM and MORE Variants --- p.25 / Chapter 2.3.3.2 --- The DLDET Variant --- p.26 / Chapter 2.3.4 --- Comparison Between Our Proposal and Related Works --- p.26 / Chapter Chapter 3 --- Min-Delay-Max-Delay TCP Buffering --- p.28 / Chapter 3.1 --- Minimum Delay --- p.29 / Chapter 3.1.1 --- Why Enabling Nagle's Algorithm Alone is Not a Solution? --- p.29 / Chapter 3.1.2 --- Advantages of Min-Delay TCP-layer Buffering versus Application-layer Buffering --- p.30 / Chapter 3.2 --- Maximum Delay --- p.32 / Chapter 3.2.1 --- Why Enabling Nagle's Algorithm Alone is Not a Solution? --- p.32 / Chapter 3.2.2 --- Advantages of Max-delay TCP Buffering versus Nagle's Algorithm --- p.33 / Chapter 3.3 --- Interaction with Nagle's Algorithm --- p.34 / Chapter 3.4 --- When to Apply Our Proposed Scheme? --- p.36 / Chapter 3.5 --- New Socket Option Description --- p.38 / Chapter 3.6 --- Implementation --- p.40 / Chapter 3.6.1 --- Small Packet Transmission Decision Logic --- p.42 / Chapter 3.6.2 --- Modified API --- p.44 / Chapter Chapter 4 --- Experiments --- p.46 / Chapter 4.1 --- The Effect of Kernel Buffering Mechanism on the Service Time --- p.47 / Chapter 4.1.1 --- Aims and Methodology --- p.47 / Chapter 4.1.2 --- Comparison of Transmission Time Required --- p.49 / Chapter 4.2 --- Performance of Min-Delay-Max-Delay Scheme --- p.56 / Chapter 4.2.1 --- Methodology --- p.56 / Chapter 4.2.1.1 --- Network Setup --- p.56 / Chapter 4.2.1.2 --- Traffic Model --- p.58 / Chapter 4.2.1.3 --- Delay Measurement --- p.60 / Chapter 4.2.2 --- Efficiency of Busy Server --- p.62 / Chapter 4.2.2.1 --- Performance of Nagle's algorithm --- p.62 / Chapter 4.2.2.2 --- Performance of Min-Delay TCP Buffering Scheme --- p.67 / Chapter 4.2.3 --- Limiting Delay by Setting TCP´ؤMAXDELAY --- p.70 / Chapter 4.3 --- Performance Sensitivity Discussion --- p.77 / Chapter 4.3.1 --- Sensitivity to Data Size per Invocation of send() --- p.77 / Chapter 4.3.2 --- Sensitivity to Minimum Delay --- p.83 / Chapter 4.3.3 --- Sensitivity to Round Trip Time --- p.85 / Chapter Chapter 5 --- Conclusion --- p.88 / Chapter Part II: --- Two Analytical Models for a Refined TCP Algorithm (TCP Veno) for Wired/Wireless Networks --- p.91 / Chapter Chapter 1 --- Introduction --- p.92 / Chapter 1.1 --- Brief Background --- p.92 / Chapter 1.2 --- Motivation and Two Analytical Models --- p.95 / Chapter 1.3 --- Organization of Part II --- p.96 / Chapter Chapter 2 --- Background --- p.97 / Chapter 2.1 --- TCP Veno Algorithm --- p.97 / Chapter 2.1.1 --- Packet Loss Type Identification --- p.97 / Chapter 2.1.2 --- Refined AIMD Algorithm --- p.99 / Chapter 2.1.2.1 --- Random Loss Management --- p.99 / Chapter 2.1.2.2 --- Congestion Management --- p.100 / Chapter 2.2 --- A Simple Model of TCP Reno --- p.101 / Chapter 2.3 --- Stochastic Modeling of TCP Reno over Lossy Channels --- p.103 / Chapter Chapter 3 --- Two Analytical Models --- p.104 / Chapter 3.1 --- Simple Model --- p.104 / Chapter 3.1.1 --- Random-loss Only Case --- p.105 / Chapter 3.1.2 --- Congestion-loss Only Case --- p.108 / Chapter 3.1.3 --- The General Case (Random + Congestion Loss) --- p.110 / Chapter 3.2 --- Markov Model --- p.115 / Chapter 3.2.1 --- Congestion Window Evolution --- p.115 / Chapter 3.2.2 --- Average Throughput Formulating --- p.119 / Chapter 3.2.2.1 --- Random-loss Only Case --- p.120 / Chapter 3.2.2.2 --- Congestion-loss Only Case --- p.122 / Chapter 3.2.2.3 --- The General Case (Random + Congestion Loss) --- p.123 / Chapter Chapter 4 --- Comparison with Experimental Results and Discussions --- p.127 / Chapter 4.1 --- Throughput versus Random Loss Probability --- p.127 / Chapter 4.2 --- Throughput versus Normalized Buffer Size --- p.132 / Chapter 4.3 --- Throughput versus Bandwidth in Asymmetric Networks --- p.135 / Chapter 4.3 --- Summary --- p.136 / Chapter Chapter 5 --- Sensitivity of TCP Veno Throughput to Various Parameters --- p.137 / Chapter 5.1 --- Multiplicative Decrease Factor (α) --- p.137 / Chapter 5.2 --- Number of Backlogs (β) and Fractional Increase Factor (γ) --- p.139 / Chapter Chapter 6 --- Conclusions --- p.142 / Bibliography --- p.144
64

Design and analysis of multi-path routing.

January 2003 (has links)
Ma Ke. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 64-68). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Motivation --- p.2 / Chapter 1.3 --- Contribution --- p.3 / Chapter 1.4 --- Organization --- p.4 / Chapter 2 --- Literature Review --- p.5 / Chapter 2.1 --- Overview --- p.5 / Chapter 2.2 --- Multi-Path Routing --- p.6 / Chapter 2.2.1 --- OSPF-ECMP --- p.7 / Chapter 2.2.2 --- LFI --- p.7 / Chapter 2.2.3 --- QSMP and QDMP --- p.9 / Chapter 2.2.4 --- WDP --- p.10 / Chapter 2.2.5 --- DMPR --- p.11 / Chapter 2.2.6 --- Cidon's Analysis --- p.13 / Chapter 3 --- LSLF and SLSLF Conditions --- p.15 / Chapter 3.1 --- Problem Formulation --- p.15 / Chapter 3.2 --- LFI Conditions --- p.16 / Chapter 3.3 --- LSLF Conditions --- p.17 / Chapter 3.4 --- SLSLF Conditions --- p.20 / Chapter 4 --- Performance of LSLF and SLSLF --- p.24 / Chapter 4.1 --- Overview --- p.24 / Chapter 4.2 --- Numerical Results --- p.26 / Chapter 5 --- Analysis of Multi-path Routing --- p.42 / Chapter 5.1 --- Assumptions --- p.43 / Chapter 5.2 --- M/M/C/C Queueing System --- p.44 / Chapter 5.3 --- Performance Analysis --- p.48 / Chapter 5.3.1 --- "Case 1 Only QoS flows between (s, d) exist" --- p.48 / Chapter 5.3.2 --- Case 2 QoS flows between other SD pairs also exist --- p.50 / Chapter 5.3.3 --- Case 3 A QoS flow can try m times before it is dropped --- p.53 / Chapter 5.4 --- Numerical Results --- p.56 / Chapter 6 --- Conclusion --- p.62
65

A unified framework for linear network coding.

January 2008 (has links)
Tan, Min. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 35-36). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Previous Work --- p.1 / Chapter 1.2 --- Motivation --- p.2 / Chapter 1.3 --- Contributions --- p.2 / Chapter 1.4 --- Thesis Organization --- p.3 / Chapter 2 --- Linear Network Coding Basics --- p.5 / Chapter 2.1 --- Formulation and Example --- p.5 / Chapter 2.2 --- Some Notations --- p.9 / Chapter 3 --- A Unified Framework --- p.13 / Chapter 3.1 --- Generic Network Codes Revisited --- p.13 / Chapter 3.2 --- A Unified Framework --- p.24 / Chapter 3.3 --- Simplified Proofs --- p.29 / Chapter 4 --- Conclusion --- p.33 / Bibliography --- p.35
66

Variable-rate linear network coding.

January 2007 (has links)
Fong, Lik Hang Silas. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 40). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Linear Network Code --- p.4 / Chapter 2.1 --- Linear Network Code without Link Failures --- p.4 / Chapter 2.1.1 --- Linear Multicast and Linear Broadcast --- p.6 / Chapter 2.2 --- Linear Network Code with Link Failures --- p.8 / Chapter 2.2.1 --- Static Linear Multicast and Static Linear Broadcast --- p.9 / Chapter 3 --- Variable-Rate Linear Network Coding --- p.11 / Chapter 3.1 --- Variable-Rate Linear Network Coding without Link Failures --- p.11 / Chapter 3.1.1 --- Problem Formulation --- p.11 / Chapter 3.1.2 --- Algorithm and Analysis --- p.12 / Chapter 3.2 --- Variable-Rate Linear Network Coding with Link Failures --- p.23 / Chapter 3.2.1 --- Problem Formulation --- p.23 / Chapter 3.2.2 --- Algorithm and Analysis --- p.23 / Chapter 3.3 --- The Maximum Broadcast Rate of Linear Network Code --- p.28 / Chapter 4 --- Conclusion --- p.38 / Bibliography --- p.40
67

Assisted GPS solution in cellular networks /

Lissai, Gidon. January 2007 (has links)
Thesis (M.S.)--Rochester Institute of Technology, 2007. / Typescript. Includes bibliographical references.
68

Optics and virtualization as data center network infrastructure

January 2012 (has links)
The emerging cloud services have motivated a fresh look at the design of data center network infrastructure in multiple layers. To transfer the huge amount of data generated by many data intensive applications, data center network has to be fast, scalable and power efficient. To support flexible and efficient sharing in cloud services, service providers deploy a virtualization layer as part of the data center infrastructure. This thesis explores the design and performance analysis of data center network infrastructure in both physical network and virtualization layer. On the physical network design front, we present a hybrid packet/circuit switched network architecture which uses circuit switched optics to augment traditional packet-switched Ethernet in modern data centers. We show that this technique has substantial potential to improve bisection bandwidth and application performance in a cost-effective manner. To push the adoption of optical circuits in real cloud data centers, we further explore and address the circuit control issues in shared data center environments. On the virtualization layer, we present an analytical study on the network performance of virtualized data centers. Using Amazon EC2 as an experiment platform, we quantify the impact of virtualization on network performance in commercial cloud. Our findings provide valuable insights to both cloud users in moving legacy application into cloud and service providers in improving the virtualization infrastructure to support better cloud services.
69

End-to-end inference of internet performance problems

Kanuparthy, Partha V. 15 November 2012 (has links)
Inference, measurement and estimation of network path properties is a fundamental problem in distributed systems and networking. We consider a specific subclass of problems which do not require special support from the hardware or software, deployment of special devices or data from the network. Network inference is a challenging problem since Internet paths can have complex and heterogeneous configurations. Inference enables end users to understand and troubleshoot their connectivity and verify their service agreements; it has policy implications from network neutrality to broadband performance; and it empowers applications and services to adapt to network paths to improve user quality of experience. In this dissertation we develop end-to-end user-level methods, tools and services for network inference. Our contributions are as follows. We show that domain knowledge-based methods can be used to infer performance of different types of networks, containing wired and wireless links, and ranging from local area to inter-domain networks. We develop methods to infer network properties: 1. Traffic discrimination (DiffProbe), 2. Traffic shapers and policers (ShaperProbe), and 3. Shared links among multiple paths (Spectral Probing). We develop methods to understand network performance: 1. Diagnose wireless performance pathologies (WLAN-probe), and 2. Diagnose wide-area performance pathologies (Pythia). Among our contributions: We have provided ShaperProbe as a public service and it has received over 1.5 million runs from residential and commercial users, and is used to check service level agreements by thousands of residential broadband users a day. The Federal Communications Commission (FCC) has recognized DiffProbe and ShaperProbe with the best research award in the Open Internet Apps Challenge in 2011. We have written an open source performance diagnosis system, Pythia, and it is being deployed in ISPs such as the US Department of Energy ESnet in wide-area inter-domain settings. The contributions of this dissertation enable Internet transparency, performance troubleshooting and improving distributed systems performance.
70

Characterizing the effects of device components on network traffic

Sathyanarayana, Supreeth 03 April 2013 (has links)
When a network packet is formed by a computer's protocol stack, there are many components (e.g., Memory, CPU, etc.) of the computer that are involved in the process. The objective of this research is to identify, characterize and analyze the effects of the various components of a device (e.g., Memory, CPU, etc.) on the device's network traffic by measuring the changes in its network traffic with changes in its components. We also show how this characterization can be used to effectively perform counterfeit detection of devices which have counterfeit components (e.g., Memory, CPU, etc.). To obtain this characterization, we measure and apply statistical analyses like probability distribution fucntions (PDFs) on the interarrival times (IATs) of the device's network packets (e.g., ICMP, UDP, TCP, etc.). The device is then modified by changing just one component (e.g., Memory, CPU, etc.) at a time while holding the rest constant and acquiring the IATs again. This, over many such iterations provides an understanding of the effect of each component on the overall device IAT statistics. Such statistics are captured for devices (e.g., field-programmable gate arrays (FPGAs) and personal computers (PCs)) of different types. Some of these statistics remain stable across different IAT captures for the same device and differ for different devices (completely different devices or even the same device with its components changed). Hence, these statistical variations can be used to detect changes in a device's composition, which lends itself well to counterfeit detection. Counterfeit devices are abundant in today's world and cause billions of dollars of loss in revenue. Device components are substituted with inferior quality components or are replaced by lower capacity components. Armed with our understanding of the effects of various device components on the device's network traffic, we show how such substitutions or alterations of legitimate device components can be detected and hence perform effective counterfeit detection by statistically analyzing the deviation of the device's IATs from that of the original legitimate device. We perform such counterfeit detection experiments on various types of device configurations (e.g., PC with changed CPU, RAM, etc.) to prove the technique's efficacy. Since this technique is a fully network-based solution, it is also a non-destructive technique which can quickly, inexpensively and easily verify the device's legitimacy. This research also discusses the limitations of network-based counterfeit detection.

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