Thesis (PhD)--University of South Australia, 2002.

Thesis (Ph. D.)--School of Computing and Engineering. University of Missouri--Kansas City, 2006. / "A dissertation in computer networking and telecommunication networking." Advisor: Deep Medhi. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Oct. 31, 2007. Includes bibliographical references (leaves 168-172). Online version of the print edition.

Recent advances in fiber optics technology have enabled extremely high-speed transport of different forms of data, on multiple wavelengths of an optical fiber, using Dense Wavelength Division Multiplexing (DWDM). It has now become possible to deploy high-speed, multi-service networks using DWDM technology. As the amount of traffic carried has increased, any single failure can be catastrophic. Survivability becomes indispensable in such networks. Therefore, it is imperative to design networks that can quickly and efficiently recover from failures. Most research to date in survivable optical network design and operation focuses on single link failures, however, the occurrence of multiple-link failures are not uncommon in networks today. Multi-link failure scenarios can arise out of two common situations. First, an arbitrary link may fail in the network, and before that link can be repaired, another link fails, thus creating a multi-link failure sequence. Secondly, it might happen in practice that two distinct physical links may be routed via the same common duct or physical channel. A failure at that shared physical location creates a logical multiple-link failure. In this dissertation, we conduct an intensive study of mechanisms for achieving survivability in optical networks. From the many mechanisms presented in the literature the focus of this work was on protection as a mechanism of survivability. In particular four protection schemes were simulated and their results analyzed to ascertain which protection scheme achieves the best survivability in terms of number of wavelengths recovered for a specific failure scenario. A model network was chosen and the protection schemes were evaluated for both single and multiple link and node failures. As an indicator of the performance of these protection schemes over a period of time average service availability and average loss in traffic for each protection scheme was also simulated. Further simulations were conducted to observe the percentage link and node utilization of each scheme hence allowing us to determine the strain each protection scheme places on network resources when traffic in the network increases. Finally based on these simulation results, recommendations of which protection scheme and under what failure conditions they should be used are made. / Recent advances in fiber optics technology have enabled extremely high-speed transport / Thesis (M.Sc.)-University of KwaZulu-Natal, 2006. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2006.

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

Gao Yan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 70-73). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Literature Survey and Background --- p.6 / Chapter 2.1 --- Capacity of Wireless Networks --- p.6 / Chapter 2.2 --- Physical Layer Techniques --- p.8 / Chapter 2.2.1 --- Radio Propagation Models --- p.8 / Chapter 2.2.2 --- Multiple Access Techniques --- p.11 / Chapter 2.3 --- MAC layer --- p.13 / Chapter 2.3.1 --- An Introduction to the IEEE 802.11 protocol --- p.13 / Chapter 2.3.2 --- Performance Analysis of the IEEE 802.11 protocol in single cell networks --- p.15 / Chapter 3 --- Model and Methodology --- p.18 / Chapter 3.1 --- System Model --- p.18 / Chapter 3.1.1 --- DCF Model --- p.19 / Chapter 3.1.2 --- The Problems of Hidden Node --- p.21 / Chapter 3.2 --- A Methodology to Compute Throughput Capacity --- p.23 / Chapter 3.2.1 --- Constructing a Contention Graph --- p.24 / Chapter 3.2.2 --- Determining the Link Capacity Ei --- p.27 / Chapter 3.2.3 --- Determining the Channel Idle Probability zi --- p.30 / Chapter 3.2.4 --- Detennining the Collision Probability γi --- p.32 / Chapter 3.3 --- Throughput Analysis of a Chain network --- p.35 / Chapter 4 --- Applications of the Proposed Methodology --- p.38 / Chapter 4.1 --- Application 1: Determining the End-to-End Throughput Capacity in Multi-hop Networks --- p.38 / Chapter 4.1.1 --- Routing Optimization --- p.40 / Chapter 4.1.2 --- Offered Load Control --- p.45 / Chapter 4.2 --- Application 2: Determining the Equilibrium Throughput of onehop Networks --- p.47 / Chapter 4.2.1 --- Throughput Capacity of One-Hop Networks --- p.49 / Chapter 4.3 --- Application 3: Optimal Hop Distance in Multi-hop Networks --- p.51 / Chapter 4.3.1 --- Analysis of Regular One-Dimension Network --- p.51 / Chapter 4.3.2 --- Optimal Hop Distance --- p.53 / Chapter 5 --- Simulation and Validation --- p.55 / Chapter 5.1 --- Simulation Environment --- p.55 / Chapter 5.2 --- MAC layer Collisions --- p.56 / Chapter 5.3 --- Single Flow Capacity: --- p.58 / Chapter 5.4 --- Neighboring Traffic Effect: --- p.59 / Chapter 5.5 --- Routing Optimization: --- p.60 / Chapter 5.6 --- Optimal Offered Load Control: --- p.62 / Chapter 5.7 --- Optimal Hop Distance --- p.63 / Chapter 5.7.1 --- One-Source ROD Network --- p.63 / Chapter 5.7.2 --- Two-Source ROD Network --- p.64 / Chapter 5.7.3 --- Simulation Investigation on Hop Distance --- p.65 / Chapter 6 --- Related Work --- p.68 / Chapter 7 --- Conclusion --- p.69

隋著移動數據網絡的迅速發展，世界各地部署著不同制式的3G，HSPA和LTE網絡，這給移動互聯網應用帶來新的機遇和挑戰。不像他們的對手, 有線網絡，移動數據網絡有較長的延遲，較高的包率，以及急劇波動的頻寬。為了應付這些挑戰，移動無線基站往往配備較大的緩衝區（KBs以至數百多MBs），以吸收短期的頻寬波動，並促進鏈路層重傳。然而，由於大部分互聯網協議，並特別是TCP，全都假設路由器只擁有較小緩衝區，所以在移動網絡的大型緩衝區下，往往導致TCP展現出次優的性能。本論文解決兩個根本性的問題來克服這一項挑戰。首先，我們開發了一種新算法 (SoD）專門來估計網絡的鏈路緩衝區的大小和隊列長度。在今天的3G移動數據網絡，本文以大量網絡數據驅動的模擬結果證明 SoD 表現優於現有的算法，如 Max-min 和 Loss-pair。另外，我們採用 SoD算法來創造新的TCP擁塞控制模塊以解決移動網絡的大型緩衝區以及的頻寬波動問題。這個新的TCP變種，稱為 TCP- QA，在模擬情況以及移動數據網絡下均表現出大大優於現有的TCP變種，包括TCP CUBIC ，TCP Vegas，TCP Westwood，和FAST TCP。 / The rapidly emerging mobile data networks fueled by the world-wide deployment of 3G, HSPA, and LTE networks created new opportunities and challenges for developing mobile Internet applications. Unlike their wired counterpart, mobile data networks are known to exhibit longer delay, higher packet loss rate, and rapidly fluctuating bandwidth. To tackle these challenges mobile radio base stations are often equipped with large buffers (from hundreds of KBs to multi-MBs) to absorb short-term bandwidth fluctuations and to facilitate link-layer retransmissions. However as most Internet protocols in general, and TCP in particular, were designed with the assumption of small router buffer size, the large buffer in mobile networks can and do interact, often negatively, with the Internet protocols, leading to sub-optimal performance. This work tackles two fundamental problems in overcoming this challenge. First, we developed a novel Sum-of-Delays (SoD) algorithm specifically designed to estimate the link buffer size and queue length of bandwidth-varying networks. Extensive trace-driven simulation results showed that SoD outperforms existing algorithms such as max-min and loss-pair by orders of magnitude in today’s 3G mobile data networks. Second, we apply the SoD algorithm to TCP’s congestion control module to incorporate and compensate for the mobile network’s large buffer size. This new TCP variant, called TCP-Queue-length-Adaptive (TCP-QA), substantially outperforms existing TCP variants including TCP CUBIC, TCP Vegas, TCP Westwood, and FAST TCP. / Detailed summary in vernacular field only. / Chan, Chi Fung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Abstract --- p.ii / 摘要 --- p.iii / Acknowledgements --- p.iv / Contents --- p.v / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Background and Related Work --- p.5 / Chapter 2.1 --- Link Buffer Size Estimation --- p.6 / Chapter 2.2 --- Queue Length Estimation --- p.8 / Chapter 2.3 --- Performance over Fixed Networks --- p.10 / Chapter 2.4 --- Performance over Bandwidth-Varying Networks --- p.15 / Chapter Chapter 3 --- Sum-Of-Delay Method --- p.19 / Chapter Chapter 4 --- Performance Evaluation --- p.22 / Chapter 4.1 --- Link Buffer Size Estimation in Fixed Bandwidth Networks --- p.23 / Chapter 4.2 --- Link Buffer Size Estimation in Variable Bandwidth Networks --- p.25 / Chapter 4.3 --- Queue Length Estimation in Fixed Bandwidth Networks --- p.28 / Chapter 4.4 --- Queue Length Estimation in Variable Bandwidth Networks --- p.31 / Chapter 4.5 --- Convergence --- p.34 / Chapter 4.6 --- Limitations in Passive Estimation --- p.40 / Chapter Chapter 5 --- Impact of Competing Traffic --- p.42 / Chapter 5.1 --- Simulation Setup --- p.42 / Chapter 5.2 --- Link Buffer Size Estimation --- p.44 / Chapter 5.3 --- Queue Length Estimation --- p.50 / Chapter 5.4 --- Discussions --- p.54 / Chapter Chapter 6 --- TCP-Queue-Length-Adaptive (TCP-QA) --- p.56 / Chapter 6.1 --- Challenges in Mobile Networks --- p.57 / Chapter 6.2 --- Queue-Length-Adaptive Congestion Control --- p.59 / Chapter 6.3 --- Performance Comparisons --- p.65 / Chapter Chapter 7 --- Summary and Future Work --- p.76 / Bibliography --- p.78

Thesis (M.S.)--Mississippi State University. Department of Computer Science. / Title from title screen. Includes bibliographical references.

Cloud computing is a new computing paradigm that aims to transform computing services into a utility, just as providing electricity in a “pay-as-you-go” manner. Data centers are increasingly adopting virtualization technology for the purpose of server consolidation, flexible resource management and better fault tolerance. Virtualization-based cloud services host networked applications in virtual machines (VMs), with each VM provided the desired amount of resources using resource isolation mechanisms. Effective network performance isolation is fundamental to data centers, which offers significant benefit of performance predictability for applications. This research is application-driven. We study how network performance isolation can be achieved for latency-sensitive cloud applications. For media streaming applications, network performance isolation means both predicable network bandwidth and low-jittered network latency. The current resource sharing methods for VMs mainly focus on resource proportional share, whereas ignore the fact that I/O latency in VM-hosted platforms is mostly related to resource provisioning rate. The resource isolation with only quantitative promise does not sufficiently guarantee performance isolation. Even the VM is allocated with adequate resources such as CPU time and network bandwidth, problems such as network jitter (variation in packet delays) can still happen if the resources are provisioned at inappropriate moments. So in order to achieve performance isolation, the problem is not only how many/much resources each VM gets, but more importantly whether the resources are provisioned in a timely manner. How to guarantee both requirements to be achieved in resource allocation is challenging. This thesis systematically analyzes the causes of unpredictable network latency in VM-hosted platforms, with both technical discussion and experimental illustration. We identify that the varied network latency is jointly caused by VMM CPU scheduler and network traffic shaper, and then address the problem in these two parts. In our solutions, we consider the design goals of resource provisioning rate and resource proportionality as two orthogonal dimensions. In the hypervisor, a proportional share CPU scheduler with soft real-time support is proposed to guarantee predictable scheduling delay; in network traffic shaper, we introduce the concept of smooth window to smooth packet delay and apply closed-loop feedback control to maintain network bandwidth consumption. The solutions are implemented in Xen 4.1.0 and Linux 2.6.32.13, which are both the latest versions when this research was conducted. Extensive experiments have been carried out using both real-life applications and low-level benchmarks. Testing results show that the proposed solutions can effectively guarantee network performance isolation, by achieving both predefined network bandwidth and low-jittered network latency. / published_or_final_version / Computer Science / Master / Master of Philosophy

M. Tech. Electrical Engineering. / High-speed transmission network requires adequate synchronization planning for quality of service. Based on ITU-T synchronization network guidelines, this dissertation proposes a Synchronous Digital Hierachy (SDH) synchronization model catering for loop of synchronization and robust to communications links faults. From candidate schemes for providing synchronization information, we have adopted the master-slave strategy. Heuristics have been developed to assist in the allocation of primary and back-up reference clocks. The contribution lies in the systematic selection of master node placement, the distribution of the reference clock from master node to all slave nodes using shortest path and the allocation of system redundancy by means of clock priority table for each nodal clock. To cater for clock stability and accuracy, the use of atomic clock (Cesium, Rubidium) as frequency standard, in long term basis, has proven that clock s characteristics namely stability and accuracy may be controlled in the midst of jitter/wander. Fiber optics transmission medium has proven to be adequate for optimal clock dissemination with very trivial frequency deviation from the nominal positional instant, traceable to Primary Reference Clock.

M. Tech. Electrical Engineering. / This study proposes a distributive joint power and rate adaptation algorithm (JRPA) in ad hoc networks based on coupled interference minimisation. In the proposed method, the influence of coupled interference was controlled by dynamically adjusting network users' transmit power choices. The users are therefore aware of the current link status while determining their data rates. In addition, every maximize utility of other users as it maximizes its utility due to the inevitable cooperation, hence, improving a collective network performance. Solving this network utility maximization problem results in a supermodular game equivalence where users cooperate to maximise both local and global utility, hence the supermodular game theory concept was used to analyse the optimality and convergence of the proposed solution.