This thesis develops efficient tools for modelling wireless communications within highly resonant environments. The aim of these tools is to augment analysis of wireless systems inside closed metallic cavity environments. The primary application for these systems is within the aerospace industry where weight and space are restricted and robustness is critical. The use of ever-advancing wireless communication options would offer significant weight and cost savings and increase safety through supplementing or the replacement of wired systems. The use of a low power wireless system offers the greatest advantage in terms of flexibility and weight. Accordingly, the most suitable applications of the wireless systems are discussed in terms of existing avionic systems. The electromagnetic properties of the aircraft environment and parameters to characterise both the properties of the environment and the wireless signal are introduced. Efficient models are then developed, which characterise the resonant and associated multipath nature of the cavity based on an equivalent circuit approach. The efficiency of these models permits the use of a statistical modelling approach, akin to reverberation chamber measurement techniques, in order to generalise the results for typically non-constant modal structures. Finally, a fractional boundary placement model is developed to augment the transmission line modelling method and permit boundary placement at non-integer positions within a structured mesh. The technique provides a semi-conformal capability with no deleterious impact on the modelling time step. This is then extended to a dynamic model for modelling structural variations during the simulation. A subset of wireless communication approaches is presented and the effectiveness and suitability of such systems are discussed. The developed models are applied to characteristic environments and a selection of the wireless communication methodologies in order to provide examples of their use and an insight into the effect of these environments upon a wireless system.

The increasing popularity of computing devices with short-range wireless offers new communication service opportunities. These devices are small and may be mobile or embedded in almost any type of object imaginable, including cars, tools, appliances, clothing and various consumer goods. The majority of them can store data and transmit it when a wireless, or wired, transmitting medium is available. The mobility of the individuals carrying such short-range wireless devices is important because varying distances creates connection opportunities and disconnections. It is likely that successful forwarding algorithms will be based, at least in part, on the patterns of mobility that are seen in real settings. For this reason, studying human mobility in different environments for extended periods of time is essential. Thus we need to use measurements from realistic settings to drive the development and evaluation of appropriate forwarding algorithms. Recently, several significant efforts have been made to collect data reflecting human mobility. However, these traces are from specific scenarios and their validity is difficult to generalize. In this thesis we contribute to this effort by studying human mobility in shopping malls. We ran a field trial to collect real-world Bluetooth contact data from shop employees and clerks in a shopping mall over six days. This data will allow the informed design of forwarding policies and algorithms for such settings and scenarios, and determine the effects of users' mobility patterns on the prevalence of networking opportunities. Using this data set we have analysed human mobility and interaction patterns in this shopping mall environment. We present evidence of distinct classes of mobility in this situation and characterize them in terms of power law coefficients which approximate inter-contact time distributions. These results are quite different from previous studies in other environments. We have developed a software tool which implements a mobility model for "structured" scenarios such as shopping malls, trade fairs, music festivals, stadiums and museums. In this thesis we define as structured environment, a scenario having definite and highly organised structure, where people are organised by characteristic patterns of relationship and mobility. We analysed the contact traces collected on the field to guide the design of this mobility model. We show that our synthetic mobility model produces inter-contact time and contact duration distributions which approximate well to those of the real traces. Our scenario generator also implements several random mobility models. We compared our Shopping Mall mobility model to three other random mobility models by comparing the performances of two benchmark delay tolerant routing protocols, Epidemic and Prophet, when simulated with movement traces from each model. Thus, we demonstrate that the choice of a mobility model is a significant consideration when designing and evaluating delay-tolerant mobile ad-hoc network protocols. Finally, we have also conducted an initial study to evaluate the effect of delivering messages in shopping mall environments by exclusively forwarding them to customers or sellers, each of which has distinctive mobility patterns.

Telecommunications is one of our most critical national infrastructures, enabling many other infrastructure sectors to function. The federal oversight structure for this sector, put in place by the Department of Homeland Security, relies heavily on voluntary cooperation between the public and private sectors. Given that no large-scale disruption of the nationwide telecommunications backbone has occurred, there is no empirical evidence showing the effectiveness of the structure DHS has put in place. In an effort to gauge the effectiveness of the various existing infrastructure oversight structures, this thesis examines four specific roles assumed by the federal government and their performance in their respective sectors. These roles and sectors are Owner (aviation), Customer (power), Coordinator (local telecommunications), and Regulator (food). Each case is reviewed to determine the effects of the government role on economic impact of the disruption, the time required to restore initial operating capabilities, and the time required to restore full operating capabilities. The various cases show that the government role has little direct impact on the costs related to infrastructure disruptions. The Regulator role had a negative impact on timelines for both initial and full restoration. The other roles all made positive contributions to both restoration timelines. / US Air Force (USAF) author.

A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Mathematical statistics. Johannesburg, February 2014. / In this study we examine the question of which statistical mod- els work well in predicting customer defection in the retail mobile telecommunication industry. For each of the two data sets that were used (mobile call pattern and billing, and time taken to churn data), four statistical models were tted and compared namely; arti cial neural networks, decision trees, logistic regression and support vector machines. The arti cial neural network model proved to be supe- rior than the other three models when tted on both data sets. This model gave the best area under the receiver operating characteristic curve (0.93 for call pattern data and 0.88 for billing and time taken to churn data), highest lift at 10 per cent of the population (7.01 for call pattern data and 2.12 for billing and time taken to churn data) and lowest misclassi cation rate (0.04 for call pattern data and 0.19 for billing and time taken to churn data). The logistic regression model under performed the other models when tted to call pattern data and came out as third when tted to billing and time taken to churn data whereby they outperformed the decision tree model. Support vector machine came out as the second best model for billing and time taken to churn data and third when tted to call pattern data. Decision tree model performed well when tted to call pattern data and worst when tted to billing and time taken to churn data The study showed that in the retail mobile telecommunication industry, companies can increase revenue streams and competitive advantage by using data mining techniques to predict customers that are likely to churn. The next step for the business is to embark on retention programs to use these methods to reduce churners.

A thesis submitted to the Faculty of Engineering. University of the Witwatersrand. Johannesburg in fulfilment of the requirements for the degree of Doctor of Philosophy. / The general argument of the thesis is that the design of broadband antennas demands a thorough understanding of the factors influencing the current distribution on antenna wires. Specifically. current distribution concepts are used to improve the evaluation and design of small broadband antennas for the high frequency (HF) 2 to 30 MHz range. The current distribution on an antenna governs its input impedance, radiation efficiency and radiation patterns. (Abbreviation abstract) / Andrew Chakane 2018

by Ling Wai Chee, Sarah, Mak Wai Kwan, Max. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 83-86). / ABSTRACT --- p.ii / TABLE OF CONTENTS --- p.v / LIST OF TABLES --- p.viii / ACKNOWLEDGMENTS --- p.ix / Chapter / Chapter I. --- INTRODUCTION --- p.1 / The Liberalization Trend --- p.2 / Telecommunications Liberalization in Hong Kong --- p.3 / Liberalization of Customer Premises Equipment in the 1980s --- p.3 / Liberalization of Special Telecommunications Services --- p.4 / Liberalization of Local Fixed Telecommunications Market --- p.4 / Liberalization of International Telecommunications Market --- p.5 / Liberalization of Telecommunications between HK and PRC --- p.7 / Research Objectives --- p.7 / Chapter II. --- METHODOLOGY --- p.10 / Methodology Overview --- p.10 / In-Depth Interview --- p.10 / Survey --- p.12 / Data Analysis --- p.15 / Interpretation and Strategic Implications --- p.16 / Chapter III. --- THE HK TELECOMMUNICATIONS MARKET AND SERVICES --- p.17 / Market Overview --- p.17 / Telephone Services --- p.18 / Data Line Services --- p.18 / Value-added Services --- p.19 / Electronic Data Interchange --- p.19 / Video-On-Demand --- p.20 / Wireless Telecommunications Services --- p.21 / Mobile Phone Services --- p.22 / Paging Services --- p.23 / Mobile Data --- p.24 / International Services --- p.24 / Chapter IV. --- THE TELECOMMUNICATION MARKET PLAYERS --- p.27 / Local Carriers in Hong Kong --- p.27 / New T&T (Wharf Group) --- p.28 / New World Telephone (New World Group) --- p.30 / Hutchison Communication (Hutchison Group) --- p.31 / The Incumbent - Hongkong Telecom --- p.32 / Chapter V. --- FINDINGS - EXPLORATORY RESEARCH FACTORS FOR SELECTING A TELECOMMUNICATIONS CARRIER --- p.34 / Price --- p.34 / Geographic Coverage --- p.35 / Service Reliability --- p.36 / Maintenance Service --- p.37 / Sales and Pre-sales Service --- p.39 / Comprehensiveness of Service Offerings --- p.39 / Single Carrier --- p.40 / Telephone Service --- p.41 / Business Flexibility --- p.41 / Future Direction for Advanced Services --- p.42 / Chapter VI. --- FINDINGS - DESCRIPTIVE RESEARCH --- p.43 / Questionnaire Design --- p.43 / Questionnaire Responses --- p.44 / General Observation --- p.44 / Chapter VII. --- STRATEGIC IMPLICATIONS --- p.52 / Implications for Market Positioning --- p.52 / Positioning Alternatives --- p.52 / Positioning for Specific Factors --- p.53 / Positioning for Service Reliability --- p.54 / Positioning for Good Maintenance Service --- p.57 / Positioning for Good Sales and Pre-sales Service --- p.61 / Positioning for Comprehensive Geographic Coverage --- p.64 / Positioning for Comprehensive Service Offerings --- p.68 / Summary of Positioning for Specific Factors --- p.73 / Positioning for Specific Market Segments --- p.74 / Chapter VIII. --- LIMITATIONS --- p.76 / APPENDIX --- p.78 / BIBLIOGRAPHY --- p.83

by Lo Man Keung. / Abstract in Chinese and English. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1987. / Bibliography: leaves 80-81.

by Wong, Kwok-wai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 90-93). / DEDICATION / ACKNOWLEDGEMENTS / ABSTRACT / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter CHAPTER 2 --- BASIC OSCILLATOR DESIGN --- p.5 / Chapter CHAPTER 3 --- FUNDAMENTAL INJECTION LOCKING --- p.12 / Chapter 3.1 --- INTRODUCTION --- p.12 / Chapter 3.2 --- NONLINEAR OSCILLATOR MODELS --- p.13 / Chapter 3.3 --- TYPES OF INJECTION LOCKED OSCILLATOR --- p.24 / Chapter 3.4 --- INJECTION LOCKING CHARACTERISTICS --- p.26 / Chapter 3.5 --- CONCLUSION --- p.31 / Chapter CHAPTER 4 --- SUBHARMONIC INJECTION LOCKING --- p.32 / Chapter 4.1 --- INTRODUCTION --- p.32 / Chapter 4.2 --- SUBHARMONIC INJECTION LOCKING --- p.32 / Chapter 4.3 --- SUBHARMONIC INJECTION LOCKING CHARACTERISTICS --- p.36 / Chapter 4.4 --- CONCLUSION --- p.40 / Chapter CHAPTER 5 --- EXPERIMENTAL INVESTIGATIONS ON INJECTION LOCKING --- p.41 / Chapter 5.1 --- INTRODUCTION --- p.41 / Chapter 5.2 --- EXPERIMENTAL CHARACTERISTICS --- p.43 / Chapter 5.3 --- NON-INTEGRAL SUBHARMONIC LOCKING --- p.53 / Chapter 5.3.1 --- Nonlinear feedback model --- p.53 / Chapter 5.3.2 --- Circuit description --- p.55 / Chapter 5.3.3 --- Experimental results --- p.59 / Chapter 5.3.4 --- Summary --- p.64 / Chapter 5.4 --- SELECTIVE SUBHARMONIC LOCKING RANGE ENHANCEMENT --- p.65 / Chapter 5.4.1 --- Mulit-feedback nonlinear model --- p.65 / Chapter 5.4.2 --- Circuit description --- p.65 / Chapter 5.4.3 --- Experimental results --- p.69 / Chapter 5.4.4 --- Summary --- p.71 / Chapter 5.5 --- FEEDBACK TYPE INJECTION LOCKED OSCILLATOR --- p.72 / Chapter 5.5.1 --- Feedback type injection locked oscillator model with different injection points --- p.72 / Chapter 5.5.2 --- Circuit description --- p.73 / Chapter 5.5.3 --- Experimental results --- p.76 / Chapter 5.5.4 --- Summary --- p.76 / Chapter 5.6 --- PHASE TUNING BEYOUND 180 DEGREES BY INJECTION LOCKING --- p.79 / Chapter 5.6.1 --- Phase change by single injection locking --- p.79 / Chapter 5.6.2 --- Phase change by cascaded injection locking --- p.80 / Chapter 5.6.3 --- Experimental results --- p.85 / Chapter 5.6.4 --- Summary --- p.88 / Chapter 5.7 --- CONCLUSION --- p.88 / Chapter CHAPTER 6 --- CONCLUSION --- p.89 / REFERENCES --- p.90 / LIST OF ACCEPTED AND SUBMITTED / PUBLICATIONS DURING THE PERIOD OF STUDY

by Hau Ka Pun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 102-[103]). / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- A General Review of MDCS --- p.1 / Chapter 1.2 --- MDCS with Independent Data Streams --- p.4 / Chapter 1.3 --- Admissible Coding Rate Region --- p.5 / Chapter 1.4 --- Distribution of Information in Different Encoders --- p.6 / Chapter 1.5 --- Multilevel Diversity Coding by Superposition --- p.8 / Chapter 1.6 --- Optimality of Superposition --- p.11 / Chapter 1.7 --- Different MDCS coding schemes --- p.17 / Chapter 2 --- MDCS's with Three Encoders --- p.20 / Chapter 2.1 --- 2-level-3-encoder MDCS --- p.21 / Chapter 2.2 --- 3-level-3-encoder MDCS --- p.31 / Chapter 3 --- Symmetrical Multilevel Diversity Coding System --- p.49 / Chapter 3.1 --- Introduction --- p.49 / Chapter 3.2 --- "SMDCS[2,m,(l,m)]" --- p.53 / Chapter 3.3 --- "SMDCS[3， m,(l,2,m)]" --- p.56 / Chapter 3.4 --- "SMDCS[3,m,(l,3,m)]" --- p.62 / Chapter 3.5 --- "SMDCS[4,4, (1,2,3,4)]" --- p.66 / Chapter 4 --- Convex Analysis of Coding Rate Region of DCS --- p.72 / Chapter 4.1 --- Introduction --- p.72 / Chapter 4.2 --- Polyhedral Sets --- p.73 / Chapter 4.3 --- Addition of Polyhedral Sets --- p.75 / Chapter 4.4 --- Algorithms to Enumerate Extreme Points and Decompose Tuples --- p.86 / Chapter 5 --- Conclusion and Further Research --- p.90 / Chapter 5.1 --- Conclusion --- p.90 / Chapter 5.2 --- Suggestions for Further Research --- p.91 / Appendix --- p.93 / Chapter A --- Proof of Equivalence of rsp and Rsp in Chapter3 --- p.93 / Chapter A.1 --- r2m1m and R2m1m --- p.93 / Chapter A.2 --- r33123 and R33123 --- p.94 / Chapter A.3 --- r441234 and. R441234 --- p.96 / Chapter B --- A Class of MDCS Where Superposition is Always Not Optimal --- p.99 / Bibliography --- p.102

Wong, Wing-ming Eric. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves 46-47. / ACKNOWLEDGMENTS / ABSTRACT / Chapter Chapter 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Advantages and Disadvantages --- p.1 / Chapter 1.2 --- Satellite System Engineering --- p.2 / Chapter 1.3 --- Channel Allocation Methods --- p.3 / Chapter 1.4 --- Outline of this Thesis --- p.5 / Chapter Chapter 2 --- DELAY BOUNDS --- p.6 / Chapter 2.1 --- Introduction --- p.6 / Chapter 2.2 --- The Packet Satellite System --- p.7 / Chapter 2.3 --- The Idealized Protocol with Contention-Free Reservation --- p.8 / Chapter 2.4 --- Delay Lower Bound for Protocols with Contention-Free Reservation --- p.9 / Chapter 2.5 --- Delay Lower Bound for Protocols with Contention-Based Reservation --- p.14 / Chapter Chapter 3 --- IN SEARCH OF A MINIMUM DELAY PROTOCOL --- p.23 / Chapter 3.1 --- Introduction --- p.23 / Chapter 3.2 --- The Packet Satellite System --- p.25 / Chapter 3.3 --- The Transmission Protocol --- p.26 / Chapter 3.4 --- Throughput Analysis --- p.27 / Chapter 3.5 --- Delay Analysis --- p.28 / Chapter 3.6 --- Minimization of DI --- p.31 / Chapter 3.7 --- Minimization of DII --- p.38 / Chapter 3.8 --- Numerical Examples --- p.38 / Chapter Chapter 4 --- CONCLUSIONS --- p.45 / REFERENCES --- p.46 / APPENDIX --- p.48