Li Xin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 81-86). / Abstracts in English and Chinese. / COHERENT OPTICAL CODE DIVISION MULTIPLE ACCESS BASED ON SUPERSTRUCTURE FIBER BRAGG GRATING ENCODERS AND DECODERS --- p.1 / ACKNOWLEDGEMENT --- p.2 / ABSTRACT --- p.III / 摘要 --- p.V / CONTENTS --- p.VI / LIST OF FIGURES --- p.1 / Chapter CHAPTER 1 --- INTRODUCTION --- p.3 / Chapter 1.1 --- Overview of OCDMA --- p.3 / Chapter 1.2 --- Classification of OCDMA Schemes --- p.6 / Chapter 1.3 --- Introduction of Coherent OCDMA Schemes --- p.9 / Chapter 1.4 --- Introduction of superstructure Fiber Bragg Gratings and Other Encoding and Decoding Components --- p.10 / Chapter 1.5 --- Outline of the Thesis --- p.13 / Chapter CHAPTER 2 --- COUPLED MODE THEORY AND SUPERSTRUCTURE FIBER BRAGG GRATING SIMULATION MODEL --- p.16 / Chapter 2.1 --- Fiber Bragg Grating Model Based on Coupled Mode Theory --- p.16 / Chapter 2.1.1 --- Introduction of FBG and the Coupled Mode Theory --- p.16 / Chapter 2.1.2 --- FBG Model Based on CMT --- p.18 / Chapter 2.1.3 --- FBG Model When there are Phase Discontinuities Between Different Parts --- p.20 / Chapter 2.2 --- Properties of Fiber Bragg Gratings --- p.22 / Chapter 2.3 --- Simulation Model of superstructure Fiber Bragg Gratings --- p.27 / Chapter 2.4 --- Summary --- p.31 / Chapter CHAPTER 3 --- COHERENT OCDMA CODING SCHEME BASED ON THE SUPERSTRUCTURE FIBER BRAGG GRATING ENCODER/DECODER --- p.33 / Chapter 3.1 --- Introduction and Theoretical Derivation of the Coding Scheme --- p.33 / Chapter 3.1.1 --- Introduction of the Coding Scheme --- p.33 / Chapter 3.1.2 --- Derivation of SSFBG Encoder --- p.34 / Chapter 3.1.3 --- Encoding for the SSFBG --- p.39 / Chapter 3.2 --- Introduction of the Simulation Model and the Research on It …… --- p.44 / Chapter 3.3 --- Summary --- p.47 / Chapter CHAPTER 4 --- RESEARCH ON THE SIMULATED COHERENT OCDMA SYSTEM IN IDEAL CASE --- p.48 / Chapter 4.1 --- Introduction of the ideal case and factors that affect the system performance --- p.48 / Chapter 4.2 --- Effects by Refractive Index Modulation of the SSFBG Encoder --- p.49 / Chapter 4.3 --- Effects by Code Type --- p.54 / Chapter 4.4 --- Effect by the Code Length --- p.57 / Chapter 4.5 --- Summary --- p.60 / Chapter CHAPTER 5 --- RESEARCH ON THE SIMULATED COHERENT OCDMA SYSTEM IN PRACTICAL ENVIRONMENT --- p.62 / Chapter 5.1 --- Introduction --- p.62 / Chapter 5.2 --- Comparison of System Performance in Synchronous and Asynchronous Cases --- p.63 / Chapter 5.3 --- Discussion on the System Performance When Users are In Different Power Levels --- p.65 / Chapter 5.4 --- Analysis of Channel Noise In the Coherent OCDMA System --- p.68 / Chapter 5.5 --- Summary --- p.70 / Chapter CHAPTER 6 --- CONCLUSIONS AND FUTURE WORK --- p.72 / Chapter 6.1 --- Conclusions --- p.72 / Chapter 6.2 --- Future Work --- p.75 / APPENDIX A PROOF OF SSFBG THEORETICAL MODEL APPROXIMATION --- p.77 / "APPENDIX B RANDOM SEQUENCE, M-SEQUENCE AND WALSH SEQUENCE" --- p.80 / REFERENCES --- p.81

Huang Yi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 97-98). / Abstracts in English and Chinese. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgments --- p.iv / Contents --- p.v / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- CTDMA for Multicarrier Communication Systems --- p.2 / Chapter 1.2 --- Contributions of This Thesis --- p.4 / Chapter 1.3 --- Outline of This Thesis --- p.6 / Chapter Chapter 2 --- Multicarrier Communication Systems --- p.8 / Chapter 2.1 --- Multicarrier Modulation (MCM) Scheme versus Single Carrier Modulation (SCM) Scheme --- p.9 / Chapter 2.2 --- Orthogonal Frequency Division Multiplexing (OFDM) Systems --- p.12 / Chapter 2.3 --- Multicarrier CDMA --- p.16 / Chapter Chapter 3 --- Data Rate Guaranteed CTDMA for Multicarrier Communication Systems --- p.21 / Chapter 3.1 --- Code Time Division Multiple Access (CTDMA) --- p.22 / Chapter 3.2 --- Mathematical Programming --- p.28 / Chapter 3.3 --- Near Optimal CTDMA Approach --- p.32 / Chapter 3.4 --- Ad Hoc CTDMA Approach --- p.48 / Chapter 3.5 --- Lower Bound on Optimization --- p.61 / Chapter 3.6 --- Performance Evaluation --- p.64 / Chapter Chapter 4 --- Code Assignment for Multicarrier Communication Systems with Quantized Feedback --- p.73 / Chapter 4.1 --- Code Assignment for Fully Loaded Systems --- p.74 / Chapter 4.2 --- Random Orthogonal Codes --- p.76 / Chapter 4.3 --- Wireless Fading Channel Model --- p.78 / Chapter 4.4 --- Performance Evaluation of One-to-one Assignment --- p.80 / Chapter 4.5 --- Code Assignment for Non-fully Loaded Systems --- p.89 / Chapter 4.6 --- Performance Evaluation of Multiple-to-one Assignment --- p.90 / References --- p.97

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.

Kin Kwong Leung. / "August 15, 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 77-[82]). / 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.

by Yeung Chi Kit. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 89-91). / Chapter I --- Hybrid FDMA/CDMA Wireless ATM --- p.1 / Chapter 1 --- Introduction --- p.2 / Chapter 1.1 --- Motivation --- p.2 / Chapter 1.2 --- Thesis Organization (PART I) --- p.5 / Chapter 2 --- Fundamentals --- p.6 / Chapter 2.1 --- Spread Spectrum --- p.6 / Chapter 2.1.1 --- Direct Sequence (DS) CDMA --- p.6 / Chapter 2.1.2 --- Frequency Hopping (FH) CDMA --- p.8 / Chapter 2.1.3 --- Time Hopping (TH) CDMA --- p.8 / Chapter 2.1.4 --- MC-CDMA (Multicarrier-CDMA) --- p.9 / Chapter 2.2 --- Asynchronous Transfer Mode (ATM) --- p.10 / Chapter 3 --- System Model --- p.12 / Chapter 4 --- System Capacity --- p.16 / Chapter 4.0.1 --- One Homogeneous User Population --- p.16 / Chapter 4.0.2 --- Two Homogeneous User Populations --- p.18 / Chapter 5 --- Conclusion --- p.24 / Chapter II --- Subband Image Coding --- p.28 / Chapter 6 --- Introduction --- p.29 / Chapter 6.1 --- Motivation --- p.29 / Chapter 6.2 --- Thesis Organization (PART II) --- p.31 / Chapter 7 --- Fundamentals --- p.33 / Chapter 7.1 --- Image Fidelity Criteria --- p.33 / Chapter 7.1.1 --- Numerical (Quantitative) Measures --- p.34 / Chapter 7.1.2 --- Perceptual (Subjective) Measure --- p.34 / Chapter 8 --- Wavelet Transform --- p.36 / Chapter 8.1 --- Wavelet Theory --- p.37 / Chapter 8.2 --- Multiresolution Analysis --- p.39 / Chapter 8.3 --- Quality Criteria for Wavelets --- p.42 / Chapter 8.4 --- Criteria for filters...................´ب --- p.43 / Chapter 8.5 --- Orthogonal Discrete Wavelet Transform --- p.45 / Chapter 8.6 --- Biorthogonal Discrete Wavelet Transform --- p.47 / Chapter 8.7 --- Wavelet Packets Transform --- p.48 / Chapter 8.8 --- Appendix --- p.50 / Chapter 8.8.1 --- QMF & CQF --- p.50 / Chapter 8.8.2 --- Examples of Orthogonal Filters --- p.53 / Chapter 8.8.3 --- Examples of Biorthogonal Filters --- p.53 / Chapter 9 --- Transform Coding and Compression --- p.55 / Chapter 9.1 --- Transformation Techniques --- p.56 / Chapter 9.2 --- Quantization --- p.57 / Chapter 9.2.1 --- Scalar Quantization --- p.57 / Chapter 9.2.2 --- Llyod-Max Quantization --- p.59 / Chapter 9.2.3 --- Vector Quantization --- p.59 / Chapter 9.2.4 --- Successive Approximation Entropy-Coded Quantization --- p.60 / Chapter 9.3 --- Entropy Coding --- p.61 / Chapter 9.3.1 --- Huffman Coding --- p.61 / Chapter 9.3.2 --- Arithmetic Coding --- p.62 / Chapter 9.3.3 --- Dictionary Based Coding --- p.64 / Chapter 9.3.4 --- Run Length Coding --- p.65 / Chapter 9.3.5 --- Example --- p.65 / Chapter 10 --- Embedded Zerotree Algorithm --- p.69 / Chapter 10.1 --- Significance Map Encoding --- p.70 / Chapter 10.2 --- Successive Approximation Entropy Coded Quantization --- p.72 / Chapter 10.3 --- Example --- p.74 / Chapter 10.4 --- Comments on EZW --- p.77 / Chapter 11 --- Residue Coding Using Embedded Zerotree Algorithm --- p.79 / Chapter 11.1 --- Residue Coding --- p.80 / Chapter 11.2 --- Results --- p.81 / Chapter 12 --- Conclusion --- p.86

One of the fundamental problems related to the development of direct sequence code division multiple access (DS CDMA) wireless data networks is design of spreading sequences possessing semi-optimal characteristics. In this thesis, we introduce three new methods to design spreading sequences, which can be optimised to achieve the desired characteristics.We show that the level of MAI for the DS CDMA systems utilising the example sets of sequences designed by the use of these techniques can be relatively low, compare to the case when the well known Gold-like sequences [29] are used. In addition, we show that by using one of the methods introduced in the thesis, we can construct sets of orthogonal sequences possessing acceptable correlation properties, even for an asynchronous operation, while another of the introduced methods can be used if design of sequences of an arbitrary length is required.Our new methods to design complex polyphase sequences are orientated towards the short length sequences, as a target application for them are high data rate wireless networks. Those methods are based on using discretised chirp pulses, pulses consisting of discretised multiple chirps, or linear combinations of them. In order to achieve orthogonality among the designed polyphase sequences, we combined the sequences based on superimposed chirps and double chirps with the sequences derived from the orthogonal Walsh functions.Finally, we utilise the three most promising sequence sets designed by the use of die introduced methods to simulate the multiuser DS CDMA systems. We compare performance of those simulated systems with the performance of the simulated system utilising 15-chip Gold- like sequences. The comparison results indicate that by using our design methods, we can produce useful sequence sets for applications where short spreading sequences are required. The presented ++ / results also demonstrate that the performance of systems utilising those sequences can be significantly better in terms of the number of simultaneously active users or bit error rate (BER) that the performance of the system employing Gold or Gold-like sequences of the similar length.

The focus of this thesis is on the resource allocation problems in wireless sensor and cooperative networks. Typically, wireless sensor networks operate with limited energy and bandwidth are often required to meet some specified Quality-of-Service (QoS) constraints. The ultimate objective for the majority of the problems considered in this thesis is to save battery energy and maximize the network lifetime. / In the first part of this thesis, we employ complex mathematical models to emulate a variety of power drains in wireless sensor nodes. In the first instance, we address a lifetime optimization problem of a wireless TDMA/CDMA sensor network for joint transmit power and rate allocations. The effect of fast fading is captured by including rate outage and link outage constraints on each link. After that, a single-hop wireless sensor network is deployed for a certain application - to estimate a Gaussian source within a pre-specified distortion threshold. In this part, we consider lifetime maximization, in different multiple access protocols such as TDMA, an interference limited non-orthogonal multiple access (NOMA) and an idealized Gaussian multiple access channel. This problem is further studied in a multi-hop scenario where sensing and receiving powers are also included in addition to transmission power. Finally, we investigate a balancing problem between the source coding and transmission power for video wireless sensor systems where the sensor node is required to send the collected video clips, through wireless media, to a base station within a corresponding distortion threshold. All these energy saving and lifetime optimization problems in sensor networks can be formulated via nonlinear nonconvex optimization problems, which are generally hard to solve. However, with favourable variable substitution and reasonable approximation, most of these problems are shown to be convex. The only exception is the Gaussian source esitmation problem in NOMA scenario for which we provide a simple successive convex approximation based algorithm for the NOMA case that converges fast to a suboptimal solution. / In the second part of the thesis, we propose an optimal power allocation scheme with a K-block coding delay constraint on data transmission using a three node cooperative relay network assuming a block fading channel model. Channel information is fed back to the transmitter only in a causal fashion, so that the optimal power allocation strategy is only based on the current and past channel gains. We consider the two simplest schemes for information transmission using a three node (a source, a relay and a destination) relay network, namely the amplify and forward (AF) and decode and forward (DF) protocols. We use the dynamic programming methodology to solve the (K-block delay constrained) expected capacity maximization problem and the outage probability minimization problem with a short term sum power (total transmission power of the source and the relay) constraint. / The main contribution of the thesis is a comprehensive suite of power minimization and lifetime maximization methods that can be used in wireless sensor networks. We present several such applications and extensive numerical examples at the end of each chapter.

This thesis addresses handoff issues in a WCDMA system with space-time block coded transmit antenna diversity. Soft handoff has traditionally been used in CDMA systems because of its ability to provide an improved link performance due to the inherent macro diversity. Next generation systems will incorporate transmit diversity schemes employing several transmit antennas at the base station. These schemes have been shown to improve downlink transmission performance especially capacity and quality. This research investigates the possibility that the diversity obtained through soft handoff can be compensated for by the diversity obtained in a transmit diversity system with hard handoff. We analyze the system for two performance measures, namely, the probability of bit error and the outage probability, in order to determine whether the improvement in link performance, as a result of transmit diversity in a system with hard handoffs obviates the need for soft handoffs.

Recently, the transmission of vector quantization (VQ) over a code-division multiple access (CDMA) channel has received a considerable attention in research community. The complexity of the optimal decoding for VQ in CDMA communications is prohibitive for implementation, especially for systems with a medium or large number of users. A suboptimal approach to VQ decoding over a CDMA channel, disturbed by additive white Gaussian noise (AWGN), was recently developed. Such a suboptimal decoder is built from a soft-output multiuser detector (MUD), a soft bit estimator and the optimal soft VQ decoders of individual users. <p>Due to its lower complexity and good performance, such a decoding scheme is an attractive alternative to the complicated optimal decoder. It is necessary to extend this decoding scheme for a frequency-selective Rayleigh fading CDMA channel, a channel model typically seen in mobile wireless communications. This is precisely the objective of this thesis. <p>Furthermore, the suboptimal decoders are obtained not only for binary phase shift keying (BPSK), but also for M-ary pulse amplitude modulation (M-PAM). This extension offers a flexible trade-off between spectrum efficiency and performance of the systems. In addition, two algorithms based on distance measure and reliability processing are introduced as other alternatives to the suboptimal decoder. <p>Simulation results indicate that the suboptimal decoders studied in this thesis also performs very well over a frequency-selective Rayleigh fading CDMA channel.

Recently, the transmission of vector quantization (VQ) over a code-division multiple access (CDMA) channel has received a considerable attention in research community. The complexity of the optimal decoding for VQ in CDMA communications is prohibitive for implementation, especially for systems with a medium or large number of users. A suboptimal approach to VQ decoding over a CDMA channel, disturbed by additive white Gaussian noise (AWGN), was recently developed. Such a suboptimal decoder is built from a soft-output multiuser detector (MUD), a soft bit estimator and the optimal soft VQ decoders of individual users. <p>Due to its lower complexity and good performance, such a decoding scheme is an attractive alternative to the complicated optimal decoder. It is necessary to extend this decoding scheme for a frequency-selective Rayleigh fading CDMA channel, a channel model typically seen in mobile wireless communications. This is precisely the objective of this thesis. <p>Furthermore, the suboptimal decoders are obtained not only for binary phase shift keying (BPSK), but also for M-ary pulse amplitude modulation (M-PAM). This extension offers a flexible trade-off between spectrum efficiency and performance of the systems. In addition, two algorithms based on distance measure and reliability processing are introduced as other alternatives to the suboptimal decoder. <p>Simulation results indicate that the suboptimal decoders studied in this thesis also performs very well over a frequency-selective Rayleigh fading CDMA channel.