Yang Yang. / "July 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (2nd gr., p. 1-9). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Wan, Wing San. / "September 2010." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (p. 53-55). / Abstracts in English and Chinese. / Acknowledgements --- p.ii / Abstract --- p.iii / 摘要 --- p.iv / Contents --- p.v / Chapter Chapter 1 --- INTRODUCTION --- p.1 / Chapter Chapter 2 --- BACKGROUND AND RELATED WORK --- p.4 / Chapter 2.1 --- Sender-receiver-based approaches --- p.4 / Chapter 2.2 --- Sender-based approaches --- p.5 / Chapter 2.3 --- Receiver-based approaches --- p.6 / Chapter Chapter 3 --- TCP FLOW CONTROL REVISITED --- p.8 / Chapter Chapter 4 --- OPPORTUNISTIC TRANSMISSION --- p.12 / Chapter 4.1 --- Link bandwidth estimation --- p.16 / Chapter 4.2 --- Reception rate estimation --- p.18 / Chapter 4.3 --- Transmission scheduling --- p.19 / Chapter 4.4 --- Performance --- p.21 / Chapter Chapter 5 --- Local Retransmission --- p.23 / Chapter 5.1 --- The blackout period --- p.24 / Chapter 5.2 --- Proactive retransmission --- p.28 / Chapter 5.3 --- Performance --- p.30 / Chapter Chapter 6 --- Loss Event Suppression --- p.31 / Chapter 6.1 --- RTT modulation --- p.32 / Chapter 6.2 --- Performance --- p.35 / Chapter Chapter 7 --- Fairness --- p.37 / Chapter 7.1 --- Packet forwarding --- p.37 / Chapter 7.2 --- Non-uniform bandwidth allocation --- p.41 / Chapter Chapter 8 --- EXPERIMENTS --- p.43 / Chapter 8.1 --- Experiment setup --- p.43 / Chapter 8.2 --- Packet loss --- p.44 / Chapter 8.3 --- Unaccelerated TCP throughput --- p.45 / Chapter 8.4 --- Accelerated TCP throughput --- p.46 / Chapter 8.5 --- Fairness --- p.47 / Chapter 8.6 --- Mobile handset performance --- p.47 / Chapter Chapter 9 --- FUTURE WORK --- p.49 / Chapter 9.1 --- Dynamic AWnd control --- p.49 / Chapter 9.2 --- Split-TCP --- p.50 / Chapter 9.3 --- Dynamic resource allocation --- p.50 / Chapter 9.4 --- Sender-based acceleration --- p.51 / Chapter Chapter 10 --- CONCLUSION --- p.52 / BIBLIOGRAPHY --- p.53

Yau Chin Hang Herman. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 90-92). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- To A Localization --- p.10 / Chapter 2.1 --- Linear Estimator --- p.13 / Chapter 2.2 --- The Approximate Maximum Likelihood (AML) estimator --- p.14 / Chapter 2.3 --- Estimator for Linear BS --- p.18 / Chapter 3 --- TDoA Localization --- p.22 / Chapter 3.1 --- AML in TDoA localization --- p.27 / Chapter 4 --- Discussions of Application Considerations --- p.32 / Chapter 4.1 --- The Non-Line-of-Sight Problem --- p.33 / Chapter 4.2 --- Multipath Propagation --- p.34 / Chapter 4.3 --- Optimum placement of 4 sensors --- p.35 / Chapter 5 --- Simulation Studies --- p.44 / Chapter 5.1 --- Measures of Accuracy --- p.45 / Chapter 5.2 --- Simulations for non-linear array BSs --- p.47 / Chapter 5.2.1 --- Simulation 1: MS locating inside the enclosed area formed by 3BSs --- p.48 / Chapter 5.2.2 --- Simulation 2: The MS is outside the enclosed area formed by 3 BSs --- p.52 / Chapter 5.2.3 --- Simulation 3: The MS is inside the enclosed area formed by 6 BSs --- p.55 / Chapter 5.2.4 --- Simulation 4: The MS locates outside the enclosed area formed by 6 BSs --- p.58 / Chapter 5.3 --- ML estimator for linear array --- p.62 / Chapter 5.3.1 --- Simulation 5: Three BSs with equal spacing --- p.62 / Chapter 5.3.2 --- Simulation 6: Three BSs with non-equal spacing --- p.64 / Chapter 5.4 --- TDOA localization simulations --- p.66 / Chapter 5.4.1 --- Simulation 7: TDOA localization with 4 equal spacing microphones and the speaker is inside the enclosed area --- p.66 / Chapter 5.5 --- To see the performance of optimum placement --- p.69 / Chapter 5.5.1 --- Simulation 8: Optimum placement of the 4th microphone if the other three are fixed --- p.70 / Chapter 5.5.2 --- Simulation 9: Fixing 2 microphone and find the optimum placement of the other two microphones --- p.74 / Chapter 5.5.3 --- Simulation 10: The optimum placement of microphones without constraint --- p.78 / Chapter 6 --- Conclusions and Suggestions for future work --- p.81 / Chapter 6.1 --- Conclusions --- p.81 / Chapter 6.2 --- Suggestion for future work --- p.83 / Appendices --- p.85 / Chapter A --- The relationship between range variance and range difference variance --- p.85 / Chapter B --- The Cramer-Rao Lower Bound (CRLB) for TDoA and ToA cases --- p.87

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Thesis (DTech (Information Technology))--Cape Peninsula University of Technology, 2018. / Although the use of mobile technology features prominently in all walks of life, learning and teaching supported by its ad hoc use in higher education contexts is an under-researched topic. Moreover, elements constituting best practices for quality improvement and aimed at informing decision-making stakeholders, are spread across disparate frameworks, reported in literature. The study aimed to meet the following objectives: • O1: To identify the elements that inform strategic decisions for ad hoc mobile technology-enhanced learning. • O2: To inform the structure of the framework, defined by its constituent components. These objectives were associated with two main research questions, addressed via five secondary research questions that guided the exploration of elements associated with the ad hoc use of mobile technology-enhanced learning in a specific higher education environment. The study consequently proposed a consolidated and synthesised set of theoretically based and empirically determined elements, leading to a framework of interrelated guidelines. A moderate constructionist approach adapted from Järvensivu and Törnroos (2010) underpins the dual-purpose research design. At first, a systematic literature review explored existing frameworks applicable to e-learning, m-learning, technology-enhanced learning and blended-learning modalities. The review was subsequently expanded to include additional sources that addressed diverse aspects of mobile technology-enhanced learning. I undertook an extensive qualitative data analysis of the 55 articles resulting from the systematic literature review. Analysis techniques incorporated open, axial and selective coding, memoing, thematic analysis and the construction of network maps using ATLAS.ti V8.0, a CAQDAS tool. Outcomes of the analysis established an initial set of theoretically grounded elements, comprising a hierarchy of 11 constructs, five categories, 16 sub-categories and 60 items. Network maps demonstrated the interlinking of elements for each of the five categories titled: A. Enablement, B. Environment, C. Interactivity, D. Dynamics and E. Mobility. A final network map consolidated these individual maps, presenting the foundations for a framework for the ad hoc use of mobile technology-enhanced learning in higher education contexts. The theoretically based elements established foundations for the empirical portion of the study – a single exploratory case study defined by an architectural technology domain. The case study supported the inclusion of multiple perspectives and complex, natural contexts where mobile technology usage by stakeholders was the focus of the study. Empirical data was collected during six studies from purposively selected faculty respondents. Qualitative data analysis of collected data yielded additional empirically determined elements namely: eight constructs, eight sub-categories and 35 items. These empirically determined elements augmented findings of the systematic literature review. Additional categories did not emerge; however support for theoretically based elements was demonstrated via network maps.

Chen, Jieying. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 58-62). / Abstract in English only. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Literature Review --- p.5 / Chapter 1.3 --- Contributions Of This Thesis --- p.7 / Chapter 1.4 --- Structure Of This Thesis --- p.8 / Chapter 2 --- Problem Formulation --- p.9 / Chapter 2.1 --- The JBAPC Problem --- p.9 / Chapter 2.2 --- The Single-Stage Reformulation --- p.12 / Chapter 3 --- The BARN Algorithm --- p.15 / Chapter 3.1 --- Preliminary Mathematics --- p.15 / Chapter 3.1.1 --- Duality Of The Linear Optimization Problem --- p.15 / Chapter 3.1.2 --- Benders Decomposition --- p.18 / Chapter 3.2 --- Solving The JBAPC Problem Using BARN Algorithm --- p.21 / Chapter 3.3 --- Performance And Convergence --- p.24 / Chapter 3.3.1 --- Global Convergence --- p.26 / Chapter 3.3.2 --- BARN With Error Tolerance --- p.26 / Chapter 3.3.3 --- Trade-off Between Performance And Convergence Time --- p.26 / Chapter 4 --- Accelerating BARN --- p.30 / Chapter 4.1 --- The Relaxed Master Problem --- p.30 / Chapter 4.2 --- The Feasibility Pump Method --- p.32 / Chapter 4.3 --- A-BARN Algorithm For Solving The JBAPC Problem --- p.34 / Chapter 5 --- Computational Results --- p.36 / Chapter 5.1 --- Global Optimality And Convergence --- p.36 / Chapter 5.2 --- Average Convergence Time --- p.37 / Chapter 5.3 --- Trade-off Between Performance And Convergence Time --- p.38 / Chapter 5.4 --- Average Algorithm Performance Of BARN and A-BARN --- p.39 / Chapter 6 --- Discussions --- p.47 / Chapter 6.1 --- Resource Allocation In The Uplink Multi-cell Networks --- p.47 / Chapter 6.2 --- JBAPC Problem In The Uplink Multi-cell Networks --- p.48 / Chapter 7 --- Conclusion --- p.50 / Chapter 7.1 --- Conclusion Of This Thesis --- p.50 / Chapter 7.2 --- Future Work --- p.51 / Chapter A --- The Proof --- p.52 / Chapter A.l --- Proof of Lemma 1 --- p.52 / Chapter A.2 --- Proof of Lemma 3 --- p.55 / Bibliography --- p.58

Our society increasingly relies on the Internet for common services like online banking, shopping, and socializing. Many of these services heavily depend on secure end-to-end transactions to transfer personal, financial, or other sensitive information. At the core of ensuring secure transactions are the TLS/SSL protocol and the ``trust'' relationships between all involved partners. In this thesis we passively monitor the HTTPS traffic between a campus network and the Internet, and characterize the certificate usage and trust relationships in this complex landscape. By comparing our observations against known vulnerabilities and problems, we provide an overview of the actual security that typical Internet users (such as the people on campus) experience. Our measurements cover both mobile and stationary users, consider the involved trust relationships, and provide insights into how the HTTPS protocol is used and the weaknesses observed in practice.

Success of Wireless Sensor Networks (WSN) largely depends on whether the deployed network can provide desired area coverage with acceptable network lifetime. In hostile or harsh environments such as enemy territories in battlefields, fire or chemical spills, it is impossible to deploy the sensor nodes in a predeter- mined regular topology to guarantee adequate coverage. Random deployment is thus more practical and feasible for large target areas. On the other hand, random deployment of sensors is highly susceptible to the occurrence of coverage holes in the target area. A potential solution for enhancing the existing coverage achieved by random deployments involves the use of mobility capable sensors that would help fill the coverage holes. This thesis seeks to address the problem of determining the current coverage achieved by the non-deterministic deployment of static sensor nodes and subsequently enhancing the coverage using mobile sensors. The main contributions of this dissertation are the design and evaluation of MAPC (Mobility Assisted Probabilistic Coverage), a distributed protocol for ensuring area coverage in hybrid wireless sensor networks. The primary contribution is a pragmatic approach to sensor coverage and maintenance that we hope would lower the technical barriers to its field deployment. Most of the assumptions made in the MAPC protocol are realistic and implementable in real-life applications e.g., practical boundary estimation, coverage calculations based on a realistic sensing model, and use of movement triggering thresholds based on real radio characteristics etc. The MAPC is a comprehensive three phase protocol. In the first phase, the static sensors calculate the area coverage using the Probabilistic Coverage Algorithm (PCA). This is a deviation from the idealistic assumption used in the binary detection model, wherein a sensor can sense accurately within a well defined (usually circular) region. Static sensors execute the PCA algorithm, in a distributed way, to identify any holes in the coverage. In the second phase, MAPC scheme moves the mobile nodes in an optimal manner to fill these uncovered locations. For different types of initial deployments, the proposed movement algorithms consume only 30-40% of the energy consumed by the basic virtual force algorithm. In addition, this thesis addresses the problem of coverage loss due to damaged and energy depleted nodes. The problem has been formulated as an Integer Linear Program and implementable heuristics are developed that perform close to optimal solutions. By replacing in-operational nodes in phase three, MAPC scheme ensures the continuous operation of the WSN. Experiments with real mote hardware were conducted to validate the boundary and coverage estimation part of the MAPC protocol. Extensive discrete event simulations (using NS2) were also performed for the complete MAPC protocol and the results demonstrate that MAPC can enhance and maintain the area coverage by efficiently moving mobile sensor nodes to strategic positions in the uncovered area.

The IP Multimedia Subsystem (IMS) is the technology that will merge the Internet (packet switching) with the cellular world (circuit switching). It will make Internet technologies, such as the web, email, instant messaging, presence, and videoconferencing available nearly everywhere. Presence is one of the basic services that is likely to become omnipresent in IMS. It is the service that allows a user to be informed about the reachability, availability, and willingness of communication of another user. Push to talk over Cellular (PoC) is another service in IMS that is intended to provide rapid communications for business and consumer customers of mobile networks. In order to become a truly successful mass-market service for the consumer segment, the only realistic alternative is a standardized Push-to-talk solution providing full interoperability between terminals and operators. Instant Messaging (IM) is the service that allows an IMS user to send some content to another user in near real-time. This service works under IETF’s Message Session Relay protocol (MSRP) to overcome the congestion control problem. We believe the efficiency of these services along with the mobility management in IMS session establishment has not been sufficiently investigated.In this research work, we identify the key issues to improve the existing protocols in IMS for better system behaviour. The work is centred on the three services of IMS: (1) Presence Service, (2) Push-to-Talk over cellular and, (3) Instant Messaging and over the issue of (4) IMS session set up. The existing session establishment scenario of IP Multimedia Subsystem (IMS) suffers from triangular routing for a certain period of time when an end IMS user or terminal is mobile. In this thesis, the performance of three possible session establishment scenarios in a mobile environment is compared by using an analytical model. The model is developed based on the expressions of cost functions, which represents system delay and overhead involved in sessions’ establishment. The other problem areas in optimizing presence service, dimensioning a PoC service and analysing service rates of IM relay extensions in IMS are identified. A presence server becomes overloaded when massive number of IMS terminals joins a network to request presence facility. Performance models are developed in this research to mitigate such load during heavy traffic for the presence service. Queuing analyses for different cases are provided while instant messaging chunks go through two consecutive relay nodes. The specific factors such as blocking probability, stability conditions, optimized subscription lifetime etc. in IMS environment parameters have been investigated. We have also elaborated models to dimension a PoC service for service providers with regards to controlling PoC session access, optimal PoC session timer, path optimization and number of allowable simultaneous PoC sessions for given network grade of service.In a nutshell, the contribution of this dissertation are: (a) a proposed robust scheduler to improve performance of the IMS presence service, (b) several derived models to dimension IMS Push-to-talk over cellular service, (c) a new mechanism to reduce cost for the IMS session set ups in mobile environment and (d) evaluation of message blocking and stability in IMS Instant Messaging (IM) service by applying queuing theories. All of these analyses have resulted in recommendations for the performance enhancements with optimal resource utilization in IMS framework.