Yeung Man Chun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 84-86). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Graph Theory --- p.5 / Chapter 1.2 --- Classical Routing Algorithms --- p.10 / Chapter 1.2.1 --- Proactive Routing Algorithms --- p.11 / Chapter 1.2.2 --- Reactive Routing Algorithms --- p.13 / Chapter 1.3 --- Wireless Ad Hoc Routing Algorithms --- p.15 / Chapter 1.5 --- Organization of the Thesis --- p.17 / Chapter Chapter 2 --- General Routing Algorithm --- p.18 / Chapter 2.1 --- Pre-routing Cost and On-routing Cost --- p.18 / Chapter 2.2 --- Rewritten Bellman-Ford Algorithm --- p.20 / Chapter 2.3 --- A Hybrid Algorithm --- p.22 / Chapter 2.4 --- Routable Condition --- p.33 / Chapter 2.5 --- A Better Algorithm? --- p.43 / Chapter Chapter 3 --- Clique Routing Algorithm --- p.45 / Chapter 3.1 --- Clique Process --- p.45 / Chapter 3.2 --- Property --- p.49 / Chapter 3.3 --- Decentralized Construction of the Clique Process --- p.55 / Chapter 3.4 --- Construction of a Clique Process Based GRA --- p.61 / Chapter 3.5 --- Other Alternatives --- p.68 / Chapter Chapter 4 --- Simulations and Results --- p.70 / Chapter 4.1 --- Models and Assumptions --- p.70 / Chapter 4.2 --- Results --- p.72 / Chapter 4.2.1 --- Pre-routing Cost --- p.73 / Chapter 4.2.2 --- On-routing Cost --- p.76 / Chapter 4.2.3 --- Reliability --- p.77 / Chapter Chpater 5 --- Conclusions --- p.80 / References --- p.84

Lam, Kim Yung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 87-92). / Abstract also in Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Rayleigh Fading Channels --- p.1 / Chapter 1.2 --- Wireless Ad Hoc Networks --- p.3 / Chapter 1.3 --- Ad Hoc Routing Protocols --- p.3 / Chapter 1.4 --- Information Capacity --- p.4 / Chapter 1.5 --- Cooperative Communications --- p.6 / Chapter 1.6 --- Outline of Thesis --- p.7 / Chapter 2 --- Background and Related Work --- p.8 / Chapter 2.1 --- Cooperative Communications --- p.8 / Chapter 2.1.1 --- Cooperative Diversity --- p.8 / Chapter 2.1.2 --- User Cooperation --- p.10 / Chapter 2.1.3 --- Coded Cooperation --- p.11 / Chapter 2.2 --- Cooperative Routing --- p.12 / Chapter 2.3 --- Information-Theoretic Study --- p.16 / Chapter 2.4 --- Optimization techniques --- p.17 / Chapter 3 --- Single-Source Single-Destination Cooperative Routing --- p.21 / Chapter 3.1 --- System Model --- p.22 / Chapter 3.1.1 --- Network Assumptions --- p.22 / Chapter 3.1.2 --- Routing Process --- p.22 / Chapter 3.1.3 --- Transmitting Signal --- p.23 / Chapter 3.1.4 --- Link Cost Formulation --- p.23 / Chapter 3.2 --- Minimum Energy Cooperative Route --- p.25 / Chapter 3.2.1 --- Cooperative Graph --- p.25 / Chapter 3.2.2 --- An Example of the Cooperative Graph --- p.27 / Chapter 3.2.3 --- Non-reducible property of the Cooperative Graph --- p.29 / Chapter 3.3 --- Optimized Scheduling --- p.32 / Chapter 3.3.1 --- KKT conditions --- p.32 / Chapter 3.3.2 --- Newton´ةs Method --- p.34 / Chapter 3.4 --- Complexity Analysis --- p.35 / Chapter 3.5 --- Simplified Scheduling Process --- p.37 / Chapter 3.5.1 --- Linear relationship in low rate regime --- p.37 / Chapter 3.5.2 --- The Simplified Scheduling Algorithm --- p.39 / Chapter 4 --- Heuristic Single-Source Cooperative Routing Schemes --- p.41 / Chapter 4.1 --- Maximum Hops Cut --- p.42 / Chapter 4.1.1 --- The Routing Protocol --- p.42 / Chapter 4.1.2 --- Simulations --- p.46 / Chapter 4.2 --- Maximum Relays Subgraph --- p.47 / Chapter 4.2.1 --- The Routing Protocol --- p.47 / Chapter 4.2.2 --- Simulations --- p.51 / Chapter 4.3 --- Adaptive Maximum Relays Subgraph --- p.55 / Chapter 4.3.1 --- The Routing Protocol --- p.55 / Chapter 4.3.2 --- Simulations --- p.57 / Chapter 4.4 --- Comparison of three protocols --- p.60 / Chapter 4.4.1 --- Implementation --- p.60 / Chapter 4.4.2 --- Cooperative Performance --- p.60 / Chapter 4.5 --- Enhancement of the algorithms --- p.61 / Chapter 4.5.1 --- Conclusion --- p.63 / Chapter 5 --- Multiplexing Cooperative Routes in Multi-source Networks --- p.64 / Chapter 5.1 --- Problem Formation --- p.65 / Chapter 5.1.1 --- The Network Model --- p.65 / Chapter 5.1.2 --- Objective Aim --- p.65 / Chapter 5.1.3 --- Link Cost Formulation --- p.66 / Chapter 5.1.4 --- Time Sharing and Interference --- p.66 / Chapter 5.1.5 --- Multiple Sources Consideration --- p.67 / Chapter 5.2 --- Multi-Source Route-Multiplexing Protocols --- p.68 / Chapter 5.2.1 --- Full Combination with Interference (FCI) --- p.68 / Chapter 5.2.2 --- Full Combination with Time Sharing (FCTS) --- p.68 / Chapter 5.2.3 --- Selection Between Interference and Time Sharing (SBITS) --- p.69 / Chapter 5.2.4 --- Interference and time sharing combinations --- p.71 / Chapter 5.2.5 --- The Simplified Version for SBITS --- p.72 / Chapter 5.3 --- Stage Cost Calculation --- p.73 / Chapter 5.3.1 --- Total stage cost formation in the sub timeslot --- p.73 / Chapter 5.3.2 --- Total stage cost formulation in different routing protocols --- p.74 / Chapter 5.3.3 --- Multiplexing for non-uniform timeslot routes --- p.75 / Chapter 5.4 --- Simulation --- p.76 / Chapter 5.4.1 --- Simulation model --- p.76 / Chapter 5.4.2 --- Simulation detail --- p.77 / Chapter 5.4.3 --- Simulation evaluation --- p.78 / Chapter 6 --- Conclusion and Future Work --- p.83 / Chapter 6.1 --- Conclusion --- p.83 / Chapter 6.2 --- Future Work --- p.84 / Chapter 6.2.1 --- Multiple-Source System Optimal Route --- p.84 / Chapter 6.2.2 --- Better Relay-Selection Policy --- p.85 / Chapter 6.2.3 --- Single Optimization for Minimum Energy Cooperative Route --- p.85 / Chapter 6.2.4 --- Dynamic Programming for Minimum Energy Cooperative Route --- p.85 / Chapter 6.2.5 --- Min-Max Problem --- p.85 / Chapter 6.2.6 --- Distributed Algorithm --- p.86 / Chapter 6.2.7 --- Game Theory --- p.86 / Bibliography --- p.87

Cheung, Man Hon. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 89-94). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Rayleigh Fading Channels --- p.1 / Chapter 1.2 --- Ultra-Wideband (UWB) Communications --- p.2 / Chapter 1.2.1 --- Definition --- p.2 / Chapter 1.2.2 --- Characteristics --- p.3 / Chapter 1.2.3 --- UWB Signals --- p.4 / Chapter 1.2.4 --- Applications --- p.5 / Chapter 1.3 --- Cooperative Communications --- p.7 / Chapter 1.4 --- Outline of Thesis --- p.7 / Chapter 2 --- Background Study --- p.9 / Chapter 2.1 --- Interference-Aware Routing --- p.9 / Chapter 2.2 --- Routing in UWB Wireless Networks --- p.11 / Chapter 2.3 --- Cooperative Communications and Routing --- p.12 / Chapter 3 --- Cooperative Routing in Rayleigh Fading Channel --- p.15 / Chapter 3.1 --- System Model --- p.16 / Chapter 3.1.1 --- Transmitted Signal --- p.16 / Chapter 3.1.2 --- Received Signal and Maximal-Ratio Combining (MRC) --- p.16 / Chapter 3.1.3 --- Probability of Outage --- p.18 / Chapter 3.2 --- Cooperation Criteria and Power Distribution --- p.21 / Chapter 3.2.1 --- Optimal Power Distribution Ratio --- p.21 / Chapter 3.2.2 --- Near-Optimal Power Distribution Ratio β´ة --- p.21 / Chapter 3.2.3 --- Cooperation or Not? --- p.23 / Chapter 3.3 --- Performance Analysis and Evaluation --- p.26 / Chapter 3.3.1 --- 1D Poisson Random Network --- p.26 / Chapter 3.3.2 --- 2D Grid Network --- p.28 / Chapter 3.4 --- Cooperative Routing Algorithm --- p.32 / Chapter 3.4.1 --- Cooperative Routing Algorithm --- p.33 / Chapter 3.4.2 --- 2D Random Network --- p.35 / Chapter 4 --- UWB System Model and BER Expression --- p.37 / Chapter 4.1 --- Transmit Signal --- p.37 / Chapter 4.2 --- Channel Model --- p.39 / Chapter 4.3 --- Received Signal --- p.39 / Chapter 4.4 --- Rake Receiver with Maximal-Ratio Combining (MRC) --- p.41 / Chapter 4.5 --- BER in the presence of AWGN & MUI --- p.46 / Chapter 4.6 --- Rake Receivers --- p.47 / Chapter 4.7 --- Comparison of Simple Routing Algorithms in ID Network --- p.49 / Chapter 5 --- Interference-Aware Routing in UWB Wireless Networks --- p.57 / Chapter 5.1 --- Problem Formulation --- p.57 / Chapter 5.2 --- Optimal Interference-Aware Routing --- p.58 / Chapter 5.2.1 --- Link Cost --- p.58 / Chapter 5.2.2 --- Per-Hop BER Requirement and Scaling Effect --- p.59 / Chapter 5.2.3 --- Optimal Interference-Aware Routing --- p.61 / Chapter 5.3 --- Performance Evaluation --- p.64 / Chapter 6 --- Cooperative Routing in UWB Wireless Networks --- p.69 / Chapter 6.1 --- Two-Node Cooperative Communication --- p.69 / Chapter 6.1.1 --- Received Signal for Non-Cooperative Communication --- p.69 / Chapter 6.1.2 --- Received Signal for Two-Node Cooperative Communication --- p.70 / Chapter 6.1.3 --- Probability of Error --- p.71 / Chapter 6.2 --- Problem Formulation --- p.75 / Chapter 6.3 --- Cooperative Routing Algorithm --- p.77 / Chapter 6.4 --- Performance Evaluation --- p.80 / Chapter 7 --- Conclusion and Future Work --- p.85 / Chapter 7.1 --- Conclusion --- p.85 / Chapter 7.2 --- Future Work --- p.86 / Chapter 7.2.1 --- Distributed Algorithm --- p.87 / Chapter 7.2.2 --- Performance Analysis in Random Networks --- p.87 / Chapter 7.2.3 --- Cross-Layer Optimization --- p.87 / Chapter 7.2.4 --- Game Theory --- p.87 / Chapter 7.2.5 --- Other Variations in Cooperative Schemes --- p.88 / Bibliography --- p.89

Traditionally, on-chip network communication was achieved with shared medium networks where devices shared the transmission medium with only one device driving the network at a time. To avoid performance losses, it required a fast bus arbitration logic. However, a single shared bus has serious limitations with the heterogeneous and multi-core communication requirements of today's chip designs. Point-to-point or direct networks solved some of the scalability issues, but the use of routers and of rather complex algorithms to connect nodes during each cycle caused new bottlenecks. As technology scales, the on-chip physical interconnect presents an increasingly limiting factor for performance and energy consumption. Network-on-chip, an emerging interconnect paradigm, provide solutions to these interconnect and communication challenges. Motivated by future bottom-up self-assembled fabrication techniques, which are believed to produce largely unstructured interconnect fabrics in a very inexpensive way, the goal of this thesis is to explore the design trade-offs of such irregular, heterogeneous, and unreliable networks. The important measures we care about for our complex on-chip network models are the information transfer, congestion avoidance, throughput, and latency. We use two control parameters and a network model inspired by Watts and Strogatz's small-world network model to generate a large class of different networks. We then evaluate their cost and performance and introduce a function which allows us to systematically explore the trade-offs between cost and performance depending on the designer's requirement. We further evaluate these networks under different traffic conditions and introduce an adaptive and topology-agnostic ant routing algorithm that does not require any global control and avoids network congestion.

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.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (M.S.)--State University of New York at Binghamton, Dept. of Electrical & Computer Engineering, 2006. / Includes bibliographical references.

En la actualidad se están realizando diversos esfuerzos para realizar la visión fu-turista de las redes de telecomunicación autogestionadas. La gestión basada en políticas ha sido reconocida como una herramienta potencial para habilitar esta visión. Mayorita-riamente, ésta técnica ha sido reconocida como proveedora de flexibilidad, adaptabilidad y soporte para asignar recursos, controlar Calidad de Servicio y seguridad, de una manera automática y de acuerdo a reglas administrativas. Adicionalmente, se ha considerado que la gestión basada en políticas proveería tal flexibilidad en tiempo de ejecución y como resultado de cambios en la red, interacciones entre usuarios, aplicaciones y disponibilidad de recursos. A pesar de enormes esfuerzos realizados con lenguajes de especificación de políticas, arquitecturas de gestión en diversos dominios y estandarización, la gestión ba-sada en políticas aún no es una realidad. Una de las razones para la reticencia en su utili-zación es la dificultad para analizar políticas que garanticen estabilidad en el sistema. Además de la problemática asociada a la gestión de conflictos entre políticas, otro obstá-culo para su utilización es la dificultad de derivar políticas ejecutables alineadas a objeti-vos administrativos o a otras políticas de alto nivel. Este último es el problema del refi namiento de políticas.Esta Tesis aborda el problema crítico de refinamiento de políticas. Damos una vi-sión completa del proceso de refinamiento, desde el análisis formal hasta su realización práctica, identificando los elementos que intervienen en cada paso de tal proceso. Inicialmente, proponemos un marco de trabajo para refinamiento de políticas ba-sado en Lógica Lineal Temporal, una lógica estándar que permite el análisis en sistemas reactivos. Esta técnica es utilizada para representar políticas a diferentes niveles jerár-quicos de abstracción. Acto seguido desarrollamos mecanismos que habilitan la obten-ción de políticas ejecutables a partir de ciertos requerimientos mediante la utilización de técnicas de exploración de estados basados en Lógica Lineal Temporal. Adicionalmente, aclaramos e identificamos las actividades y tareas de gestión de las partes administrativas durante el ciclo de vida de un sistema de gestión basado en políticas, desde la perspectiva del proceso de refinamiento de políticas. Esta Tesis presenta también directrices para abordar el proceso de refinamiento de políticas en contextos de gestión de red. Damos un paso adelante en la materialización de este proceso mediante la utilización de propiedades estructurales inherentes a sistemas de gestión de red. Proveemos, en fin, una metodología para aplicar los conceptos introduci-dos en el marco de trabajo desarrollado en esta Tesis en sistemas de gestión de red. En esta Tesis también realizamos un proceso de refinamiento de políticas com-pleto. Detallamos la realización de tal proceso en una solución exitosa de gestión basada en políticas. Tomando como base el dominio de Gestión de Calidad de Servicio, aclara-mos y presentamos las implicaciones del problema de refinamiento en este dominio de aplicación. / Current research efforts are being directed to commit with the long-term view of self management properties for telecommunications networks. One of the key approaches that have been recognised as an enabler of such a view is policy-based management. Pol-icy-based management has been mostly acknowledged as a methodology that provides flexibility, adaptability and support to automatically assign network resources, control Quality of Service and security, by considering administratively specified rules. The hype of policy-based management was to commit with these features in run-time as a result of changeable network conditions resulting from the interactions of users, applications and existing resources. Despite enormous efforts with policy languages, management archi-tectures using policy in different application domains, standardisation and industrial ef-forts, policy-based management is still not a reality. One reason behind the reticence for its use is the difficulty to analyse policies that guarantee configuration stability. In addi-tion to policy conflict analysis, a key issue for this reticence is the need to derive en-forceable policies from high level administrative goals or from higher level policies, namely the policy refinement process.This Thesis deals with the critical nature of addressing the policy refinement problem. We provide a holistic view of this process, from formal analysis to its practical realisation, identifying the key elements involved in each step of such critical process. We initially propose a policy refinement framework relying on Linear Temporal Logic (LTL), a standard logic that allows analysis of reactive systems. Based on the for-mer logic, we lay down the process of representing policies at different levels of abstrac-tion. Following on with this, we develop the mechanisms that enable the abstraction of enforceable policies from hierarchical requirements in a fully automatic manner, making use of Linear Temporal Logic based state exploration techniques. In addition, we clarify and identify the activities and management tasks that the administrative parties should carry out during the life cycle of the policy-based management system, from the perspec tive of the policy refinement process.This Thesis provides the guidelines to address policy refinement in network management contexts. Concretely, we take one step ahead in the materialisation of the policy refinement process by exploiting inherent containment properties of network management systems. For this purpose we provide the methodology to apply the concepts introduced in the policy refinement framework developed in this Thesis in the above context.In this Thesis we also execute a complete and rather detailed policy refinement process for a successful policy-based management solution. Taking the intra-domain Quality of Service Management application domain as background, we clarify and pre-sent the implications of the policy refinement problem in such a concrete application do-main.

Network virtualization can offer more flexibility and better manageability for the future Internet by allowing multiple heterogeneous virtual networks (VN) to coexist on a shared infrastructure provider (InP) network. A major challenge in this respect is the VN embedding problem that deals with the efficient mapping of virtual resources on InP network resources. Previous research focused on heuristic algorithms for the VN embedding problem assuming that the InP network remains operational at all times. In this thesis, we remove that assumption by formulating the survivable virtual network embedding (SVNE) problem and developing baseline policy heuristics and an efficient hybrid policy heuristic to solve it. The hybrid policy is based on a fast re-routing strategy and utilizes a pre-reserved quota for backup on each physical link. Our evaluation results show that our proposed heuristic for SVNE outperforms baseline heuristics in terms of long term business profit for the InP, acceptance ratio, bandwidth efficiency, and response time.

As the role of the Internet has been steadily gaining in importance, overlays are increasingly being used to provide new services and to deploy older ones. Some of the services for which overlays have been proposed include multicast, quality of service (QoS), search, and resilient networks. The use of overlays, in turn, has led to more interest in improving their performance. The performance of an overlay network depends significantly on how the network is structured, i.e., the placement of the nodes in the underlying network topology, the links between the overlay nodes and the access links of these nodes. This thesis focuses on algorithms for improving the performance of