Approved for public release; distribution is unlimited / As mobile computing becomes more ubiquitous, through the use of very capable mobile computing devices and broadband wide area wireless data networks, naval aviation maintenance has an opportunity to extend the reach of the Naval Aviation Logistics Command Management Information System (NALCOMIS) to fielded aircrew, maintenance technicians, and maintenance supervisors supporting out of local area operations. The combination of the new mobile technologies and the wireless Internet makes modern Mobile Business (m-business) initiatives possible but ushers in a host of new problems and issues that are radically different from those experienced with traditional fixed electronic business (e-business) projects. This thesis examines the concept and components that comprise m-business, details wide area data over cellular technologies, and identifies problems and issues unique to m-business initiatives. Scenario-based Use Cases will be employed within the Unified Process (UP) framework to develop the three major artifacts of the UP's inception phase - the project's vision, a Use Case model, and a supplemental specification containing functional and non-functional requirements for an aircrew mobile aircraft maintenance application. The results of this study can serve as the foundation for the development of a complete mobile aircraft maintenance office. / Lieutenant Commander, United States Navy

by Ng Ho Hing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 118-120). / Abstract also in Chinese. / Abstract --- p.2 / Acknowledgement --- p.3 / Content --- p.4 / Chapter Chapter 1: --- Introduction --- p.6 / Chapter Chapter 2: --- Background and Theories --- p.11 / Chapter 2.1 --- Background History --- p.11 / Chapter 2.2 --- Circuit Theories --- p.12 / Chapter 2.3 --- Electromagnetic Wave Theories --- p.14 / Chapter 2.3.1 --- Finite Difference Time Domain Method --- p.14 / Chapter 2.4 --- Active Antenna theory --- p.23 / Chapter 2.4.1 --- Active Component Finite Difference Time Domain --- p.23 / Chapter Chapter 3: --- Injection Locked Mixer --- p.32 / Chapter 3.1 --- Introduction --- p.32 / Chapter 3.2 --- Circuit Topology and Theory --- p.32 / Chapter 3.2.1 --- Mixer Fundamental --- p.32 / Chapter 3.2.2 --- Oscillator Fundamental --- p.33 / Chapter 3.2.3 --- Injection locking theory --- p.35 / Chapter 3.2.4 --- Regenerative mixer theory --- p.38 / Chapter 3.3 --- Design Methodology --- p.40 / Chapter 3.3.1 --- DC Bias point consideration --- p.40 / Chapter 3.3.2 --- AC signal path consideration --- p.42 / Chapter 3.3.3 --- Mixing and feedback at the base-emitter junction --- p.46 / Chapter 3.3.4 --- Final Circuit Configuration --- p.48 / Chapter 3.4 --- Circuit Characteristics --- p.49 / Chapter 3.4.1 --- Experiment parameters --- p.50 / Chapter 3.4.2 --- "Relationship between conversion gain, injection power and center frequency" --- p.50 / Chapter 3.4.2 --- Locking Bandwidth and phase shift --- p.56 / Chapter 3.4.3 --- "Regenerative Effect, Mode 1 injection mixing" --- p.58 / Chapter 3.4 --- Transient simulation --- p.63 / Chapter 3.4.1 --- DC Bias Simulation --- p.64 / Chapter 3.4.2 --- AC Simulation --- p.66 / Chapter 3.5 --- Summary --- p.78 / Chapter Chapter 4: --- Injection Locked Transceiver --- p.79 / Chapter 4.1 --- System Architecture --- p.79 / Chapter 4.2 --- Circuit Design --- p.81 / Chapter 4.2.1 --- Up-conversion Consideration --- p.81 / Chapter 4.2.2 --- Local Oscillator Consideration --- p.81 / Chapter 4.2.3 --- Bias Consideration --- p.82 / Chapter 4.2.4 --- Active Down-converting Mixer --- p.83 / Chapter 4.2.5 --- Mode 2 injection Mixing --- p.85 / Chapter 4.3 --- Antenna Design --- p.85 / Chapter 4.3.1 --- Antenna Choice --- p.85 / Chapter 4.3.1 --- FDTD Characterization --- p.85 / Chapter 4.4 --- Integration --- p.87 / Chapter 4.4.1 --- Matching Techniques --- p.87 / Chapter 4.5 --- INJECTION LOCKED OSCILLATOR (LO) OPTIMIZATION --- p.89 / Chapter 4.5.1 --- Active Mixer Optimization --- p.89 / Chapter 4.6 --- Simulation using Extended FTDT --- p.90 / Chapter 4.7 --- Discussion --- p.91 / Chapter 4.8 --- Summary --- p.91 / Chapter Chapter 5: --- Injection Locked System --- p.92 / Chapter 5.1 --- Introduction --- p.92 / Chapter 5.2 --- System Requirement --- p.93 / Chapter 5.3 --- System Architecture --- p.93 / Chapter 5.3.1 --- Sub-system Choices --- p.95 / Chapter 5.3.2 --- Frequency Synthesizer --- p.96 / Chapter 5.3.3 --- Active Transceiver --- p.96 / Chapter 5.3.4 --- IF System --- p.97 / Chapter 5.4 --- System Performance --- p.98 / Chapter 5.4.1 --- Stability --- p.98 / Chapter 5.4.2 --- Field pattern of the antenna --- p.100 / Chapter 5.4.3 --- Locking Bandwidth versus Injection Power --- p.101 / Chapter 5.4.4 --- Radiative Sensitivity and Image Selectivity --- p.102 / Chapter 5.4.5 --- Intermodulation --- p.103 / Chapter 5.4.6 --- Output Power vs Injection Frequency --- p.105 / Chapter 5.4.7 --- IF Output Vs Frequency --- p.106 / Chapter 5.4.8 --- IF Output vs DC Supply --- p.107 / Chapter 5.4.9 --- Output Power --- p.108 / Chapter 5.4.10 --- Type Approval Consideration --- p.108 / Chapter 5.4.11 --- Manufacturability consideration --- p.113 / Chapter Chapter 6: --- Summary and Conclusion --- p.114 / Chapter 6.1 --- Summary and Contribution --- p.114 / Chapter 6.2 --- Future Work --- p.115 / Bibliography --- p.118 / Publication List --- p.120

by Fu Kar Kit. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 158-160). / Abstract also in Chinese. / Chapter Chapter 1: --- Introduction --- p.1 / Chapter Chapter 2: --- Background and Theories --- p.3 / Chapter 2.1 --- Background History --- p.3 / Chapter 2.2 --- Finite Difference Time Domain Method --- p.4 / Chapter 2.2.1 --- Basic Formulation --- p.4 / Chapter A ) --- Governing Equations --- p.4 / Chapter B ) --- Discretization of Differential Equations --- p.6 / Chapter C ) --- Numerical Stability --- p.7 / Chapter 2.2.2 --- Absorbing Boundary Condition ( PML - Bandlimited ) --- p.8 / Chapter A ) --- Berenger Perfectly Matched Layer --- p.8 / Chapter B ) --- "Theroy, Two-Dimensional TE Case" --- p.10 / Chapter B-1 ) --- Propagation of a Plane Wave in a PML Medium --- p.11 / Chapter B-2 ) --- Transmission of a Wave through PML-PML Interfaces --- p.15 / Chapter B-3 ) --- PML for the FD-TD technique in 2-D domain --- p.18 / Chapter C ) --- Extension to Three-Dimension Case --- p.22 / Chapter 2.2.3 --- Modeling of Source and Passive Lumped-Circuit --- p.25 / Chapter 2.2.4 --- Obtaining the frequency dependent parameters --- p.27 / Chapter 2.2.5 --- Time Domain Extrapolation --- p.29 / Chapter 2.2.6 --- Near-to-Far-Field Transformation --- p.33 / Chapter A ) --- FD-TD implementation of Near-to-Far-Field Transformation --- p.35 / Chapter B ) --- Numerical Techniques to compute the Antenna Directivity --- p.38 / Chapter 2.3 --- Transmission Line Circuit Theories --- p.40 / Chapter 2.3.1 --- Stripline --- p.43 / Chapter 2.3.2 --- Microstrip Line --- p.46 / Chapter 2.3.3 --- Quadrature 90° Hybrid --- p.50 / Chapter 2.3.4 --- Butler Matrices --- p.50 / Chapter A ) --- Types of hybrids --- p.54 / Chapter B ) --- Number of hybrids --- p.51 / Chapter C ) --- Number of fixed phase shifters --- p.51 / Chapter D ) --- Positions and magnitudes of fixed phase shifters --- p.51 / Chapter E ) --- Values of total phase shift at output ports and produced by input ports --- p.53 / Chapter 2.4 --- Antenna Theories --- p.54 / Chapter 2.4.1 --- Microstrip Patch Antenna --- p.54 / Chapter A ) --- Bandwidth Enhancement --- p.55 / Chapter B ) --- Antenna design methodology --- p.55 / Chapter B-1 ) --- Substrate selection --- p.55 / Chapter B-2 ) --- Rectangular element analysis and design --- p.56 / Chapter 1) --- Electromagnetically coupled patch --- p.57 / Chapter 2) --- Aperture coupled patch --- p.61 / Chapter 2.4.2 --- Array Antenna --- p.67 / Chapter Chapter 3: --- Butler Matrix Analysis and Design --- p.73 / Chapter 3.1 --- Circuit Topology --- p.73 / Chapter 3.1.1 --- Basic Operation of the 4x4 Butler Matrix --- p.74 / Chapter 3.2 --- Design Methodology and Circuit Characteristics --- p.75 / Chapter 3.2.1 --- 3 dB branch-line coupler --- p.76 / Chapter 3.2.2 --- 0 dB branch-line coupler --- p.79 / Chapter 3.2.3 --- 4x4 Butler matrix Beamforming network --- p.82 / Chapter Chapter 4: --- Multibeam Array Analysis and Design --- p.90 / Chapter 4.1 --- Antenna Architecture --- p.90 / Chapter 4.2 --- Antenna Design --- p.91 / Chapter 4.2.1 --- Antenna Choice --- p.91 / Chapter A ) --- Microstrip Dipole --- p.91 / Chapter B ) --- Rectangular Microstrip Patch --- p.91 / Chapter C ) --- Circular Patch --- p.92 / Chapter D ) --- Compact Patch --- p.93 / Chapter E ) --- Annular Resonators --- p.94 / Chapter F ) --- Antenna Choice of the 4x4 Butler Matrix Network --- p.94 / Chapter 4.2.2 --- Choice of Feeding and Matching Technique --- p.95 / Chapter 4.2.3 --- Basic Antenna Parameters and Measurement Technique --- p.95 / Chapter A ) --- Radiation Pattern --- p.95 / Chapter B ) --- Radiation Pattern Lobes --- p.96 / Chapter C ) --- Antenna Gain --- p.97 / Chapter D ) --- Input Impedance --- p.97 / Chapter E ) --- Bandwidth --- p.97 / Chapter 4.2.4 --- FDTD Characterization --- p.98 / Chapter 4.3 --- Multibeam Antenna Design and Optimization --- p.104 / Chapter 4.4 --- Stripline Fed - Multibeam Antenna --- p.107 / Chapter 4.4.1 --- Design Methodology of the Stripline 3 dB Hybrid --- p.109 / Chapter 4.4.2 --- Design Methodology of the Stripline 0 dB Hybrid --- p.111 / Chapter 4.4.3 --- Design Methodology of the Stripline 4x4 Butler Matrix Network --- p.113 / Chapter 4.4.4 --- Design Methodology of the Stripline Aperture Coupled Patch --- p.138 / Chapter 4.4.5 --- Design Methodology of the Stripline Multibeam Antenna --- p.142 / Chapter Chapter 5: --- Design Examples and Application of Multibeam Antenna --- p.150 / Chapter 5.1 --- Wireless Local Loop (WLL) System --- p.150 / Chapter Chapter 6: --- Conclusions and Recommendations for Future Work --- p.156 / Chapter 6.1 --- Conclusions --- p.156 / Chapter 6.2 --- Recommendations for Future Work --- p.157 / Bibliography --- p.158 / Publication List --- p.160

在信息傳輸過程中如何保證信息的安全性是通信中的重要問題之一。目前常用的保密傳輸方式是基於密鑰的加密技術，但是隨著現代無線通信網絡的發展和計算資源的不斷豐富，基於密鑰的技術在無線網絡中的應用正面臨着巨大挑戰。這些挑戰一方面來自於無線介質的開放性使得竊聽更為容易，另一方面由於動態無線網絡和自組織無線網絡的發展使得密鑰的發布和管理更為困難。因此，為解決密鑰技術所面臨的挑戰，基於物理層的保密傳輸技術研究在近些年受到了很大關注。該技術最早在七十年代由Wyner 提出，其核心思想是利用無線信道的隨機性和目標用戶與竊聽者間無線信道容量的差異，通過對發射信號進行編碼設計使得目標用戶能正確解碼信息但竊聽者卻不能。該技術的關鍵問題之一是如何對發射信號進行設計從而提高保密信息的傳輸速率（或保密容量）。本論文的主要工作即是以此出發，旨在研究不同通信場景下最優化發射信號的設計，具體而言，本論文主要研究了以下場景下的最優發射信號設計： / 本論文的第一部分考慮一個多天線的發射機傳輸保密信息給一個單天線的目標用戶，同時有多個多天線的偷聽者在偷聽的場景。我們的目標是設計最優化發射信號使得保密信息傳輸速率最大化。該優化問題的難點在於保密信息速率函數是發射信號的一個非凸函數，因而很難求解到全局最優解。我們通過運用凸鬆弛技術證明這個非凸優化問題的全局最優解可以由它的凸鬆弛問題得到，並且我們證明了最優化的發射信號方案是採用波束聚焦。以上結論在發射機完全知道和部分知道接收機的信道信息時均成立。 / 本論文的第二部分是在第一部分的基礎上考慮在發射信號中加入人為噪聲以輔助保密信息的傳輸。具體而言，發射機可以分配部分功率來發射人為噪聲以達到干擾竊聽者的接收的目的。儘管在現有很多研究中已經證明了這種人為噪聲輔助的發射方式可有效提高保密信息傳輸速率，但是如何對保密信號和人為噪聲進行聯合優化設計使得保密傳輸速率最大化的問題一直未能有效解決。在本論文中，我們給出了一種保密信號和人為噪聲聯合最優化的求解方案。該方案是基於優化理論中的半正定規劃算法來獲得全局最優解，並且該算法在發射機完全知道和部分知道接收機信道信息時均適用。 / 本論文的第三部分主要考慮的是發射機、目標用戶和偷聽者均是多天線情況下，最大化保密信息容量的發射信號設計問題。該優化問題可以看作是之前單天線目標用戶的一個推廣，但較之前的最優信號設計問題更加具有挑戰性。在目前已知的工作中，該優化問題還沒有一個有效的多項式時間算法能求解到全局最優解。這裡，我們提出了一種基於交替優化算法的發射信號設計方案來獲得（局部）最優發射信號設計。我們證明該交替優化算法可以通過迭代注水算法來實現，因而具有很低的複雜度，並且該算法可以保證收斂到原最優化問題的穩定點，因而可以在多數情況下獲得（局部）最優解。同時在該部分，我們也研究了在發射機部分知道信道信息狀態時魯棒性發射信號的設計問題，並給出了基於交替優化算法的魯棒發射信號設計。 / 除以上提到的主要結果，本論文還考慮了多播保密信息速率最優化發射信號設計，和具有中斷概率約束的保密信息速率最優化發射信號的設計。 / Security is one of the most important issues in communications. Conventional techniques for achieving confidentiality in communication networks are based on cryptographic encryption. However, for wireless networks, this technique is faced with more challenges due to the open nature of the wireless medium as well as the dynamic topology of mobile networks. In the 1970's, Wyner proposed a physical layer-based approach to achieve perfectly secure communication without using encryption. One of the key problems of Wyner's approach is how to optimally design the transmit signal such that a high secrecy rate (i.e., the data rate at which the confidential information can be securely transmitted) can be achieved. In our work, we aim to solve this transmit signal optimization problem under various scenarios using convex optimization techniques. Specifically, the thesis consists of the following three main parts: / In the first part, we consider a multi-input single-output (MISO) scenario, where a multi-antenna transmitter sends confidential information to a singleantenna legitimate receiver, in the presence of multiple multi-antenna eavesdroppers. Our goal is to maximize an achievable secrecy rate by appropriately designing the transmit signal. The challenge of this secrecy rate maximization (SRM) problem is that it is a nonconvex optimization problem by nature. We show, by convex relaxation, that this seemingly nonconvex SRM problem admits a convex equivalent under both perfect and imperfect channel state information (CSI) cases. Our result also indicates that transmit beamforming is an optimal transmit strategy, irrespective of the number of eavesdroppers and the number of antennas employed by each eavesdropper. This provides a useful design guideline for practical implementations. / In the second part, we consider a scenario where the transmitter is able to simultaneously generate artificial noise (AN) to interfere the eavesdroppers during the transmission of the confidential message. While the efficacy of AN in improving the system security has been demonstrated in many existing works, how to jointly optimize the AN and the transmit signal is still an unsolved problem. In this part, we solve this AN-aided SRM problem under the same scenario as the first part, and give an efficient, semidefinite program (SDP)- based line search approach to obtain an optimal transmit signal and AN design under both perfect and imperfect-CSI situations. / In the last part, we consider a secrecy capacity maximization (SCM) problem for a multi-input multi-output (MIMO) scenario, where the legitimate receiver and the eavesdropper are both equipped with multiple antennas. This MIMOSCM problem is a generalization of the previous MISO-SRM problems. So far there is no known efficient algorithm to solve this problem in a global optimal manner. Herein, we propose an alternating optimization algorithm to tackle the SCM problem. The proposed algorithm has a nice iterative water-filling interpretation and is guaranteed to converge to a stationary solution of the MIMO-SCM problem. Extensions to robust SCM are also investigated in this part. / Besides the above three main results, this thesis also developed some approximate solutions to the multicast SRM of multiple MISO legitimate channels overheard by multiple MIMO eavesdroppers, and to the outage-constrained SRM of an MISO legitimate channel overheard by multiple MISO eavesdroppers. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Li, Qiang. / Thesis (Ph.D.)--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. / Abstract also in Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Contributions of This Thesis --- p.3 / Chapter 1.2 --- Organization of This Thesis --- p.5 / Chapter 2 --- Fundamentals of Physical-Layer Secrecy --- p.6 / Chapter 2.1 --- Elements of Information Theoretic Security --- p.6 / Chapter 2.2 --- Transmit Design for Physical-layer Secrecy: State-of-the-Art --- p.14 / Chapter 2.2.1 --- MISO Secrecy Capacity Maximization --- p.14 / Chapter 2.2.2 --- MIMO Secrecy Capacity Maximization --- p.17 / Chapter 2.2.3 --- AN-aided Secrecy Rate Maximization --- p.21 / Chapter 2.2.4 --- Secrecy Rate Maximization with Additional Covariance Constraints --- p.24 / Chapter 2.2.5 --- Robust Transmit Design for Physical-Layer Secrecy under Imperfect CSI --- p.28 / Chapter 2.3 --- Summary --- p.36 / Chapter 2.4 --- Appendix: GSVD --- p.37 / Chapter 3 --- MISOMEs Secrecy Rate Maximization --- p.38 / Chapter 3.1 --- System Model and Problem Statement --- p.39 / Chapter 3.1.1 --- System Model --- p.39 / Chapter 3.1.2 --- Problem Statement --- p.40 / Chapter 3.2 --- An SDP Approach to SRM Problem (3.4) --- p.43 / Chapter 3.2.1 --- The Secrecy-Rate Constrained Problem --- p.44 / Chapter 3.2.2 --- The Secrecy-Rate Maximization Problem --- p.46 / Chapter 3.3 --- Secrecy-Rate Optimization with Imperfect CSI --- p.49 / Chapter 3.3.1 --- Robust Secrecy-Rate Problem Formulations --- p.49 / Chapter 3.3.2 --- The Robust Secrecy-Rate Constrained Problem --- p.50 / Chapter 3.3.3 --- The Robust Secrecy-Rate Maximization Problem --- p.53 / Chapter 3.4 --- Simulation Results --- p.55 / Chapter 3.4.1 --- The Perfect CSI Case --- p.56 / Chapter 3.4.2 --- The Imperfect CSI Case --- p.58 / Chapter 3.5 --- Summary --- p.59 / Chapter 3.6 --- Appendix --- p.61 / Chapter 3.6.1 --- Proof of Proposition 3.1 --- p.61 / Chapter 3.6.2 --- Verifying Slater's Constraint Qualification for Problem (3.10) --- p.63 / Chapter 3.6.3 --- Proof of Theorem 3.1 --- p.63 / Chapter 3.6.4 --- Relationship between Super-Eve Design and the Optimal SDP Design --- p.65 / Chapter 3.6.5 --- Proof of Proposition 3.4 --- p.67 / Chapter 3.6.6 --- Proof of Proposition 3.5 --- p.70 / Chapter 3.6.7 --- Worst-case Secrecy Rate Calculation --- p.71 / Chapter 4 --- Multicast Secrecy Rate Maximization --- p.73 / Chapter 4.1 --- System Model and Problem Statement --- p.74 / Chapter 4.2 --- An SDP Approximation to Problem (4.2) --- p.75 / Chapter 4.3 --- Simulation Results --- p.78 / Chapter 4.4 --- Summary --- p.79 / Chapter 4.5 --- Appendix --- p.81 / Chapter 4.5.1 --- Proof of Proposition 4.1 --- p.81 / Chapter 4.5.2 --- Proof of Theorem 4.1 --- p.82 / Chapter 5 --- AN-aided MISOMEs Secrecy Rate Maximization --- p.85 / Chapter 5.1 --- System Model and Problem Statement --- p.86 / Chapter 5.1.1 --- System Model --- p.86 / Chapter 5.1.2 --- Problem Statement --- p.87 / Chapter 5.2 --- An SDP-based Approach to the SRM Problem --- p.89 / Chapter 5.2.1 --- A Tight Relaxation of the SRM Problem (5.4) --- p.90 / Chapter 5.2.2 --- An SDP-based Line Search Method for the Relaxed SRM Problem (5.9) --- p.92 / Chapter 5.3 --- Robust Transmit Design for Worst-Case SRM --- p.94 / Chapter 5.3.1 --- Worst-Case Robust SRM Problem Formulation --- p.95 / Chapter 5.3.2 --- A Tight Relaxation of the WCR-SRM Problem (5.17) --- p.96 / Chapter 5.3.3 --- An SDP-based Line Search Method for the RelaxedWCRSRM Problem (5.23) --- p.98 / Chapter 5.4 --- Robust Transmit Design for Outage SRM --- p.100 / Chapter 5.4.1 --- A Sphere-bounding Safe Approximation to OCR-SRM Problem (5.29) --- p.101 / Chapter 5.5 --- Simulation Results --- p.103 / Chapter 5.5.1 --- The Perfect-CSI Case --- p.104 / Chapter 5.5.2 --- The Imperfect-CSI: Bounded Spherical Uncertainty --- p.105 / Chapter 5.5.3 --- The Imperfect-CSI: Gaussian Random Uncertainty --- p.108 / Chapter 5.6 --- Summary --- p.111 / Chapter 5.7 --- Appendix --- p.112 / Chapter 5.7.1 --- Proof of Proposition 5.1 --- p.112 / Chapter 5.7.2 --- Proof of Theorem 5.1 --- p.114 / Chapter 5.7.3 --- Proof of Theorem 5.2 --- p.117 / Chapter 6 --- Outage Secrecy Rate Maximization for MISOSEs --- p.120 / Chapter 6.1 --- System Model and Problem Statement --- p.121 / Chapter 6.2 --- A Bernstein-type Inequality-Based Safe Approximation to Problem (6.2) --- p.122 / Chapter 6.3 --- Simulation Results --- p.127 / Chapter 6.4 --- Summary --- p.128 / Chapter 6.5 --- Appendix --- p.129 / Chapter 6.5.1 --- Proof of Lemma 6.1 --- p.129 / Chapter 6.5.2 --- Proof of Proposition 6.1 --- p.130 / Chapter 7 --- MIMOME Secrecy Rate Maximization --- p.134 / Chapter 7.1 --- An Alternating Optimization Approach to the MIMO-SCM Problem (7.1) --- p.135 / Chapter 7.2 --- An Alternating Optimization Approach to theWorst-case MIMOSCM Problem --- p.140 / Chapter 7.3 --- An Alternating Optimization Approach to the Outageconstrained SCM --- p.142 / Chapter 7.4 --- Simulation Results --- p.145 / Chapter 7.4.1 --- The Perfect CSI Case --- p.146 / Chapter 7.4.2 --- The Imperfect CSI case --- p.149 / Chapter 7.5 --- Summary --- p.150 / Chapter 7.6 --- Appendix --- p.153 / Chapter 7.6.1 --- Proof of Proposition 7.1 --- p.153 / Chapter 7.6.2 --- Proof of the monotonicity of Tr(W? ) w.r.t. --- p.154 / Chapter 7.6.3 --- Proof of Proposition 7.2 --- p.155 / Chapter 8 --- Conclusion --- p.157 / Chapter 8.1 --- Summary --- p.157 / Chapter 8.2 --- Future Directions --- p.158 / Bibliography --- p.161

The recent research interest in wireless sensor networks has caused the development of many new applications and subsequently, these emerging applications have ever increasing requirements. One such requirement is that of mobility, which has inspired an entirely new array of applications in the form of mobile wireless sensor networks (MWSNs). In terms of communications, MWSNs present a challenging environment due to the high rate at which the topology may be changing. As such, the motivation of this work is to investigate potential communications solutions, in order to satisfy the performance demands of new and future MWSN applications. As such this work begins by characterising and evaluating the requirement of a large variety of these emerging applications. This thesis focuses on the area of routing, which is concerned with the reliable and timely delivery of data from multiple, mobile sensor nodes to a data sink. For this purpose the technique of gradient routing was identified as a suitable solution, since data can quickly be passed down a known gradient that is anchored at the sink. However, in a mobile network, keeping the gradient up-to-date is a key issue. This work proposes the novel use of a global time division multiple access (GTDMA) MAC as a solution to this problem, which mitigates the need for regularly flooding the network. Additionally, the concept of blind forwarding is utilised for its low overhead and high reliability through its inherent route diversity. The key contribution of this thesis is in three novel routing protocols, which use the aforementioned principles. The first protocol, PHASeR, uses a hop-count metric and encapsulates data from multiple nodes in its packets. The hop-count metric was chosen because it is simple and requires no additional hardware. The inclusion of encapsulation is intended to enable the protocol to cope with network congestion. The second protocol, LASeR, utilises location awareness to maintain a gradient and performs no encapsulation. Since many applications require location awareness, the communications systems may also take advantage of this readily available information and it can be used as a gradient metric. This protocol uses no encapsulation in order to reduce delay times. The third protocol, RASeR, uses the hop-count metric as a gradient and also does not perform encapsulation. The reduced delay time and the relaxed requirement for any existing method of location awareness makes this the most widely applicable of the three protocols. In addition to analytical expressions being derived, all three protocols are thoroughly tested through simulation. Results show the protocols to improve on the state-of-the-art and yield excellent performance over varying speeds, node numbers and data generation rates. LASeR shows the lowest overhead and delay, which comes from the advantage of having available location information. Alternatively, at the expense of increased overhead, RASeR gives comparatively high performance metrics without the need for location information. Overall, RASeR can be suitably deployed in the widest range of applications, which is taken further by including four additional modes of operation. These include a supersede mode for applications in which the timely delivery of the most recent data is prioritised. A reverse flooding mechanism, to enable the sink to broadcast control messages to the sensor nodes. An energy saving mode, which uses sleep cycles to reduce the networks power consumption, and finally a pseudo acknowledgement scheme to increase the reliability of the protocol. These additions enable RASeR to satisfy the needs of some of the most demanding MWSN applications. In order to assess the practicality of implementation, RASeR was also evaluated using a small testbed of mobile nodes. The successful results display the protocols feasibility to be implemented on commercially available hardware and its potential to be deployed in the real world. Furthermore, a key issue in the real world deployment of networks, is security and for this reason a fourth routing protocol was designed called RASeR-S. RASeR-S is based on RASeR, but introduces the use of encryption and suggests a security framework that should be followed in order to significantly reduce the possibility of a security threat. Whilst the main focus of this work is routing, alternative MAC layers are assessed for LASeR. Unlike the other two protocols, LASeR uses available location information to determine its gradient and as such, it is not reliant on the GTDMA MAC. For this reason several MAC layers are tested and the novel idea of dedicated sensing slots is introduced, as well as a network division multiple access scheme. The selected and proposed MACs are simulated and the GTDMA and two proposed protocols are shown to give the best results in certain scenarios. This work demonstrates the high levels of performance that can be achieved using gradient orientated routing in a mobile network. It has also shown that the use of a GTDMA MAC is an efficient solution to the gradient maintenance problem. The high impact of this work comes from the versatility and reliability of the presented routing protocols, which means they are able to meet the requirements of a large number of MWSN applications. Additionally, given the importance of security, RASeR-S has been designed to provide a secure and adaptable routing solution for vulnerable or sensitive applications.

Li Ning. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 52-55). / Abstracts in English and Chinese. / Acknowledgments --- p.ii / Abstract --- p.iii / 哲學碩士論文摘要 --- p.iv / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Research Background --- p.2 / Chapter 1.2 --- Contributions of the Thesis --- p.5 / Chapter 1.3 --- Organization of the Thesis --- p.6 / Chapter Chapter 2 --- Properties of OVSF Codes --- p.7 / Chapter 2.1 --- Tree-Structured Generation of OVSF Codes --- p.7 / Chapter 2.2 --- OVSF Codes Assignment --- p.10 / Chapter Chapter 3 --- Support Delayable Traffic in Wireless Networks --- p.14 / Chapter 3.1 --- System Model --- p.15 / Chapter 3.2 --- Scheduling Algorithm with Burst Adaptation --- p.17 / Chapter 3.3 --- Performance Analysis --- p.22 / Chapter 3.4 --- Simulation Results --- p.24 / Chapter Chapter 4 --- Allocate OVSF Codes with Joint Design --- p.30 / Chapter 4.1 --- Combine Number of Active Users and Error-Control Coding Scheme --- p.31 / Chapter 4.1.1 --- System Model --- p.31 / Chapter 4.1.2 --- Scheduling Algorithm Description --- p.33 / Chapter 4.1.3 --- Simulation Results --- p.35 / Chapter 4.2 --- Combine Power Adaptation and Error-Control Coding Scheme --- p.39 / Chapter 4.2.1 --- System Model --- p.39 / Chapter 4.2.2 --- Scheduling Algorithm Description --- p.41 / Chapter 4.2.3 --- Simulation Results --- p.44 / Chapter Chapter 5 --- Conclusion --- p.50 / Bibliography --- p.52

An active sensor network is a wireless network comprising a large number of mobile sensor nodes. This dissertation deals with a general model of active sensor network, heterogeneous sensor network, where sensor nodes may have different sensing ranges. The deployment problem aims at relocating a large set of sensor nodes from arbitrary locations to give a connected, hole-free and locally maximized sensing coverage of the entire network. / The major contribution of this dissertation lies in four aspects. First, it is the first work that solves the deployment problem for optimal deterministic coverage of heterogeneous sensor networks, while most existing works limit their problems on stochastic coverage and homogeneous sensing model. Second, this work envisages the use of a generalized Voronoi diagram, the power diagram, as a novel solution to geometrically analyse and visualise the coverage of a heterogeneous sensor network. Third, it an original work that applies circle packing on sensor network deployment, and analyses and proves a number of geometrical properties of circle packing. Fourth, all methods provided in this dissertation are based on localized and distributed computation; no centralized processor or common data fusion platform is assumed to exist. / This dissertation gives an algorithm to solve the self-deployment problem. It is composed three parts. In the first part, the logical topology of the sensor network is constructed as triangulation by three distributed protocols: localized Delaunay triangulation, redundant boundary edge pruning and local edge swapping. Second, the sensor nodes self-deploy to new locations that are calculated using a circle packing algorithm. The dissertation shows that the homomorphism between Voronoi and power diagrams is necessary and sufficient for the equivalences of power Delaunay triangles to Delaunay triangles. This result allows the network to preserve a unit Delaunay triangulation by localized re-triangulations among a small number of nodes. Third, the sensor nodes further relocate themselves based on a virtual force approach to eliminate all existing coverage holes and redundant overlaps. / This dissertation studies the problem of active sensor network deployment. It focuses on self-deployment, localized and distributed computation and coverage maximization of heterogeneous sensor networks. / Lam, Miu Ling. / "February 2008." / Adviser: Yun-hui Liu. / Source: Dissertation Abstracts International, Volume: 70-03, Section: B, page: 1757. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 152-158). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

As a subtopic in this thesis, we also investigate how to deal with uncertainty in the context of the traditional Straightforward Network Coding (SNC) scheme. With the proposed scheme, Soft Network Coding, only simple symbol-level network coding operation at the physical layer of the relay node can achieve even better performance than the traditional SNC scheme, which needs the complicated channel decoding and re-encoding operation. / Network coding is a promising upper layer technique first proposed in the context of wired networks. In this thesis, we investigate the application of network coding at the physical layer of wireless networks to take into account the unique properties of wireless networks. Specifically, we propose a new network coding scheme referred to as Physical layer Network Coding (PNC). PNC effects network-coding operation directly at the physical layer by proper interpretation of EM (Electromagnetic) signal received simultaneously from multiple sources. From the network point of view, this scheme can approach the min-cut throughput for both bi-direction and uni-direction linear relay networks; from the information theory point of view, this scheme can approach the capacity of two-way relay channel in the low and high SNR regions. When channel coding is considered, we could classify PNC into two classes, end-to-end coded PNC and link-by-link coded PNC. For end-to-end coded PNC, we further classify it into subclasses: PNC over infinite field (PNCI) and PNC over finite field (PNCF). For each subclass, we propose and analyze new PNC mapping schemes. For link-by-link coded PNC, we focus on the transformation from the received packet Y3 to the network coded form of unchannel-coded packet S1⊕S2, referred to as the Channel-decoding-Network-Coding process (CNC). Among three CNC designs, a matched CNC, CNC3, is of great interest due to its superior performance. Therefore, we design a new decoding algorithm at the relay node to make CNC3 feasible. Simulation result shows that the matched CNC with our new decoding algorithm outperforms the two straightforward CNC designs significantly in terms of BER without added complexity. Overall, this thesis lays down the fundamentals and foundation of PNC. And through theoretical analysis and implementation constructions, we provide insights on how good performance in wireless networks can be achieved with PNC. / Zhang, Shengli. / Adviser: Soung Chang Lieu. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3709. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 178-183). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Access scheduling is essentially power control with only on-off options. The second part is dealing with situations where user transmissions can exist simultaneously. Here, a problem of distributed power control for time varying systems is investigated in order to coordinate transmit power among users for their respective quality-of-service (QoS). We deal with a class of power control problems where the system link gains are assumed to be time varying and SIR estimates are allowed to be corrupted with bounded noises. A simple control algorithm is devised by applying a distributed, fixed-step approach. The feedback algorithm requires only local information. By modifying the fixed-step power control algorithm proposed by Sung and Wong, here we obtain a more robust version that can handle time varying link gains and measurement noises. The result extends the Foschini and Miljanic model to allow fading and measurement errors. Convergence property of the new algorithm is established. Simulation studies have been conducted and results show that it is effective. / In integrated wireless multimedia service, isochronous traffic of different connections can be scheduled by using a most regular binary sequence (MRBS). Such a sequence can schedule traffic in an evenly spaced manner to achieve any arbitrary rate asymptotically while avoiding excessive delay and buffering requirement. Flexible time slot assignment that can match requests exactly improves the bandwidth utilization efficiency in supporting multi-rate operations for traffics of various classes. The most regular binary sequence provides such a distributed solution for multi-access control that only requires a limited information exchange. Generally, the idea can be developed to support flexible resource allocation in various communication systems such as hybrid TD-CDMA and MC-CDMA systems. It results in an overall capacity gain. More interestingly, the MRBS transmission scheduling is applicable in a network sense. Deterministic end-to-end performance guarantees such as packet delay and buffering requirement can be investigated in a systematic way. Discussions of periodic binary sequences with interesting characteristics are presented in succession. / Chen Chung Shue. / "September 2005." / Adviser: Wing Shing Wong. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3984. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 154-167). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

While the bandwidth available for wireless networks is limited, the world has seen an unprecedented growth in the number of mobile subscribers and an ever increasing demand for high data rates. Therefore efficient utilisation of bandwidth to maximise link spectral efficiency and number of users that can be served simultaneously are primary goals in the design of wireless systems. To achieve these goals, in this thesis, a new non-orthogonal uplink multiple access scheme which combines the functionalities of adaptive modulation and multiple access called collaborative modulation multiple access (CMMA) is proposed. CMMA enables multiple users to access the network simultaneously and share the same bandwidth even when only a single receive antenna is available and in the presence of high channel correlation. Instead of competing for resources, users in CMMA share resources collaboratively by employing unique modulation sets (UMS) that differ in phase, power, and/or mapping structure. These UMS are designed to insure that the received signal formed from the superposition of all users' signals belongs to a composite QAM constellation (CC) with a rate equal to the sum rate of all users. The CC and its constituent UMSs are designed centrally at the BS to remove ambiguity, maximize the minimum Euclidian distance (dmin) of the CC and insure a minimum BER performance is maintained. Users collaboratively precode their transmitted signal by performing truncated channel inversion and phase rotation using channel state information (CSI ) obtained from a periodic common pilot to insure that their combined signal at the BS belongs to the CC known at the BS which in turn performs a simple joint maximum likelihood detection without the need for CSI. The coherent addition of users' power enables CMMA to achieve high link spectral efficiency at any time without extra power or bandwidth but on the expense of graceful degradation in BER performance. To improve the BER performance of CMMA while preserving its precoding and detection structure and without the need for pilot-aided channel estimation, a new selective diversity combining scheme called SC-CMMA is proposed. SC-CMMA optimises the overall group performance providing fairness and diversity gain for various users with different transmit powers and channel conditions by selecting a single antenna out of a group of L available antennas that minimises the total transmit power required for precoding at any one time. A detailed study of capacity and BER performance of CMMA and SC-CMMA is carried out under different level of channel correlations which shows that both offer high capacity gain and resilience to channel correlation. SC-CMMA capacity even increase with high channel correlation between users' channels. CMMA provides a practical solution for implementing the multiple access adder channel (MAAC) in fading environments hence a hybrid approach combining both collaborative coding and modulation referred to as H-CMMA is investigated. H-CMMA divides users into a number of subgroups where users within a subgroup are assigned the same modulation set and different multiple access codes. H-CMMA adjusts the dmin of the received CC by varying the number of subgroups which in turn varies the number of unique constellation points for the same number of users and average total power. Therefore H-CMMA can accommodate many users with different rates while flexibly managing the complexity, rate and BER performance depending on the SNR. Next a new scheme combining CMMA with opportunistic scheduling using only partial CSI at the receiver called CMMA-OS is proposed to combine both the power gain of CMMA and the multiuser diversity gain that arises from users' channel independence. To avoid the complexity and excessive feedback associated with the dynamic update of the CC, the BS takes into account the independence of users' channels in the design of the CC and its constituent UMSs but both remain unchanged thereafter. However UMS are no longer associated with users, instead channel gain's probability density function is divided into regions with identical probability and each UMS is associated with a specific region. This will simplify scheduling as users can initially chose their UMS based on their CSI and the BS will only need to resolve any collision when the channels of two or more users are located at the same region. Finally a high rate cooperative communication scheme, called cooperative modulation (CM) is proposed for cooperative multiuser systems. CM combines the reliability of the cooperative diversity with the high spectral efficiency and multiple access capabilities of CMMA. CM maintains low feedback and high spectral efficiency by restricting relaying to a single route with the best overall channel. Two possible variations of CM are proposed depending on whether CSI available only at the users or just at the BS and the selected relay. The first is referred to Precode, Amplify, and Forward (PAF) while the second one is called Decode, Remap, and Forward (DMF). A new route selection algorithm for DMF based on maximising dmin of random CC is also proposed using a novel fast low-complexity multi-stage sphere based algorithm to calculate the dmin at the relay of random CC that is used for both relay selection and detection.