Ruan, Sichao. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 62-65). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Multihop Ad Hoc Wireless Networks --- p.1 / Chapter 1.1.1 --- Introduction to Multihop Ad Hoc Networks --- p.2 / Chapter 1.1.2 --- Scalability of Ad Hoc Wireless Networks --- p.3 / Chapter 1.2 --- Hidden Terminal Problem --- p.3 / Chapter 1.3 --- Exposed Terminal Problem --- p.5 / Chapter 1.4 --- Overview of the Thesis --- p.6 / Chapter 2 --- Background --- p.8 / Chapter 2.1 --- MAC Protocols for Wireless Networks --- p.8 / Chapter 2.1.1 --- Aloha --- p.8 / Chapter 2.1.2 --- CSMA/CA --- p.9 / Chapter 2.1.3 --- IEEE 802.11 DCF Standard --- p.10 / Chapter 2.2 --- Related Work --- p.12 / Chapter 2.2.1 --- Schemes for Hidden Node Problem --- p.12 / Chapter 2.2.2 --- Schemes for Exposed Node Problem --- p.13 / Chapter 2.3 --- Tradeoff between Hidden and Exposed Nodes --- p.14 / Chapter 2.4 --- The Effect of Carrier Sensing Range --- p.17 / Chapter 3 --- Analysis on Carrier Sensing Range --- p.18 / Chapter 3.1 --- Analysis Model --- p.18 / Chapter 3.1.1 --- Terminal Configurations --- p.18 / Chapter 3.1.2 --- Timing/Packet Parameters --- p.19 / Chapter 3.1.3 --- Protocol Approximation --- p.20 / Chapter 3.1.4 --- Throughput Measurement --- p.21 / Chapter 3.2 --- Derivation of Throughput --- p.21 / Chapter 3.2.1 --- Channel Modeling --- p.22 / Chapter 3.2.2 --- Actual Transmission Rate --- p.24 / Chapter 3.2.3 --- Case One --- p.24 / Chapter 3.2.4 --- Case Two --- p.26 / Chapter 3.2.5 --- Mathematical Form of Throughput --- p.28 / Chapter 3.2.6 --- Analysis Results --- p.30 / Chapter 3.3 --- Implications --- p.31 / Chapter 3.3.1 --- Value of Sensing Range in CSMA/CA --- p.31 / Chapter 3.3.2 --- Need for New MAC Protocols --- p.32 / Chapter 4 --- MAC Protocols by Congestion Control --- p.34 / Chapter 4.1 --- Motivations and Principles --- p.34 / Chapter 4.1.1 --- Balancing Hidden and Exposed Nodes --- p.35 / Chapter 4.1.2 --- Controlling Carrier Sensing Range --- p.36 / Chapter 4.1.3 --- Non-homogenous Sensing Range --- p.36 / Chapter 4.2 --- Algorithm Descriptions --- p.38 / Chapter 4.2.1 --- Core Concept --- p.38 / Chapter 4.2.2 --- LDMI Control Scheme --- p.40 / Chapter 4.2.3 --- Tahoe Control Scheme --- p.41 / Chapter 5 --- Simulation Analysis --- p.44 / Chapter 5.1 --- Simulation Configurations --- p.44 / Chapter 5.1.1 --- Geometric Burst Traffic Model --- p.45 / Chapter 5.1.2 --- Network Topology --- p.46 / Chapter 5.1.3 --- Simulation Parameters --- p.47 / Chapter 5.2 --- Throughput Comparisons --- p.48 / Chapter 5.3 --- Fairness Comparisons --- p.50 / Chapter 5.3.1 --- Situation of Unfairness --- p.50 / Chapter 5.3.2 --- Fairness Measurement --- p.52 / Chapter 5.4 --- Convergence Comparisons --- p.54 / Chapter 5.5 --- Summary of Performance Comparison --- p.55 / Chapter 6 --- Conclusions --- p.56 / Chapter A --- Categories of CSMA/CA --- p.58 / Chapter A.1 --- 1-persistent CSMA/CA --- p.58 / Chapter A.2 --- non-persistent CSMA/CA --- p.58 / Chapter A.3 --- p-persistent CSMA/CA --- p.59 / Chapter B --- Backoff Schemes --- p.60 / Chapter B.1 --- Constant Window Backoff Scheme --- p.60 / Chapter B.2 --- Geometric Backoff Scheme --- p.60 / Chapter B.3 --- Binary Exponential Backoff Scheme --- p.61 / Bibliography --- p.62

Zheng, Xiaoting. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 64-69). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Rayleigh Fading --- p.1 / Chapter 1.2 --- Transmission Schemes --- p.2 / Chapter 1.2.1 --- Frequency Division Multiple Access(FDMA) --- p.2 / Chapter 1.2.2 --- Time Division Multiple Access(TDMA) --- p.3 / Chapter 1.2.3 --- Code Division Multiple Access(CDMA) --- p.5 / Chapter 1.2.4 --- The Broadcast Channel --- p.5 / Chapter 1.3 --- Cooperative Transmissions --- p.9 / Chapter 1.3.1 --- Relaying Protocols --- p.10 / Chapter 1.4 --- Outline of Thesis --- p.12 / Chapter 2 --- Background Study --- p.13 / Chapter 2.1 --- Superposition Coding --- p.13 / Chapter 2.2 --- Cooperative Transmission --- p.15 / Chapter 2.2.1 --- Single Source Single Destination --- p.15 / Chapter 2.2.2 --- Multiple Sources Single Destination --- p.16 / Chapter 2.2.3 --- Single Source Multiple Destinations --- p.17 / Chapter 2.2.4 --- Multiple Sources Multiple Destinations --- p.17 / Chapter 2.3 --- Power Minimization --- p.18 / Chapter 2.3.1 --- Power Minimization in Code-Multiplexing System --- p.19 / Chapter 2.3.2 --- Power Minimization in Frequency-multiplexing System --- p.19 / Chapter 2.3.3 --- Power Minimization in Time-Multiplexing System --- p.20 / Chapter 3 --- Sum Power Minimization with Superposition Coding --- p.21 / Chapter 3.1 --- System Model --- p.22 / Chapter 3.2 --- Superposition Coding Scheme --- p.22 / Chapter 3.2.1 --- Optimal Superposition Coding Scheme --- p.22 / Chapter 3.2.2 --- Sub-optimal Superposition Coding Scheme --- p.27 / Chapter 3.3 --- Performance Evaluation --- p.30 / Chapter 3.4 --- Assignment Examples for Superposition Coding Scheme --- p.33 / Chapter 4 --- Source-cooperated Transmission in a Wireless Cluster --- p.42 / Chapter 4.1 --- System Model --- p.42 / Chapter 4.2 --- Selection Protocol --- p.44 / Chapter 4.2.1 --- Protocol Description and Problem Formulation --- p.44 / Chapter 4.2.2 --- Distributed Selection Algorithm --- p.46 / Chapter 4.2.3 --- Low Rate Regime --- p.50 / Chapter 4.3 --- Simulation Results --- p.52 / Chapter 4.3.1 --- Simulation Configuration --- p.53 / Chapter 4.3.2 --- Cases with a Smaller Feasible Solution Set --- p.53 / Chapter 4.3.3 --- Cases with a Larger Feasible Solution Set --- p.56 / Chapter 5 --- Conclusion and Future Work --- p.61 / Chapter 5.1 --- Conclusion --- p.61 / Chapter 5.2 --- Future Work --- p.62 / Chapter 5.2.1 --- Fairness --- p.62 / Chapter 5.2.2 --- Distributed Algorithm --- p.63 / Chapter 5.2.3 --- Game Theory --- p.63 / Chapter 5.2.4 --- Distributed Information --- p.63 / Bibliography --- p.64

Lin, Xingqin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (p. 103-109). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Background --- p.3 / Chapter 1.2.1 --- Wireless Communication Schemes --- p.3 / Chapter 1.2.2 --- Mathematical Preliminaries --- p.8 / Chapter 1.3 --- Outline of the Thesis --- p.12 / Chapter 2 --- Learning for Parallel Gaussian Interference Channels --- p.14 / Chapter 2.1 --- System Model and Problem Formulation --- p.16 / Chapter 2.2 --- Stochastic Algorithm for Learning --- p.18 / Chapter 2.2.1 --- Algorithm Design --- p.18 / Chapter 2.2.2 --- Convergence Analysis --- p.21 / Chapter 2.3 --- Continuous Time Approximation --- p.26 / Chapter 2.4 --- Learning with Averaging --- p.28 / Chapter 2.5 --- Numerical Results --- p.29 / Chapter 3 --- Power Control for One-to-Many Transmissions --- p.34 / Chapter 3.1 --- System Model --- p.35 / Chapter 3.2 --- A GNEP Approach --- p.38 / Chapter 3.2.1 --- Problem Formulation --- p.38 / Chapter 3.2.2 --- Preliminary Results --- p.39 / Chapter 3.3 --- Algorithm Design --- p.42 / Chapter 3.4 --- Numerical Results --- p.46 / Chapter 4 --- Flow Allocation in Multiple Access Networks --- p.50 / Chapter 4.1 --- System Model and Problem Formulation --- p.52 / Chapter 4.1.1 --- System Model --- p.52 / Chapter 4.1.2 --- Problem Formulation --- p.53 / Chapter 4.2 --- Characterization of NE --- p.57 / Chapter 4.2.1 --- Feasibility Assumption --- p.57 / Chapter 4.2.2 --- Existence and Uniqueness of NE --- p.58 / Chapter 4.3 --- Distributed Algorithms Design --- p.60 / Chapter 4.3.1 --- D-SBRA --- p.60 / Chapter 4.3.2 --- P-SBRA --- p.61 / Chapter 4.3.3 --- Best Response and Layered Structure --- p.65 / Chapter 4.4 --- Performance Evaluation --- p.67 / Chapter 4.4.1 --- Protocol Evaluation --- p.67 / Chapter 4.4.2 --- Convergence and Performance --- p.69 / Chapter 4.4.3 --- Flow Distribution --- p.71 / Chapter 4.4.4 --- A Grid Network Simulation --- p.73 / Chapter 5 --- Relay Assignment in Cooperative Networks --- p.76 / Chapter 5.1 --- System Model and Problem Formulation --- p.77 / Chapter 5.1.1 --- Three-Node Relay Model --- p.77 / Chapter 5.1.2 --- Network Model --- p.78 / Chapter 5.1.3 --- Problem Formulation --- p.78 / Chapter 5.2 --- Centralized Scheme --- p.80 / Chapter 5.2.1 --- Generalized Relay Assignment --- p.80 / Chapter 5.2.2 --- Admission Control --- p.83 / Chapter 5.2.3 --- Iteration Algorithm and Some Remarks --- p.84 / Chapter 5.3 --- A Simple Distributed Algorithm --- p.84 / Chapter 5.4 --- Numerical Results --- p.86 / Chapter 6 --- Conclusions and Future Work --- p.88 / Chapter 6.1 --- Conclusions --- p.88 / Chapter 6.2 --- Future Work --- p.89 / Chapter A --- Proof of Theorem 21 --- p.93 / Chapter B --- Proof of Theorem 22 --- p.96 / Chapter C --- Proof of Proposition 31 --- p.98 / Chapter D --- Proof of Proposition 44 --- p.101 / Bibliography --- p.103

Lee, King Ho. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 69-72). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction to Wireless Technologies --- p.1 / Chapter 1.2 --- Wireless Systems --- p.2 / Chapter 1.3 --- Wireless Networks --- p.3 / Chapter 1.4 --- Multiple Access --- p.5 / Chapter 1.5 --- Objectives and Outlines of the Thesis --- p.8 / Chapter 2 --- Background Studies --- p.9 / Chapter 2.1 --- Introduction of Scheduling Models of Wireless Networks (Graph-based and Interference-based) --- p.10 / Chapter 2.2 --- Power Assignment in Interference-based Schedul- ing Model --- p.12 / Chapter 2.3 --- Motivation and Contribution --- p.14 / Chapter 3 --- Model --- p.16 / Chapter 4 --- Nonlinear Power Assignment Scheduling Algorithm --- p.22 / Chapter 4.1 --- Nonlinear Power Control Scheduling Algorithms --- p.22 / Chapter 4.2 --- Low-Disturbance Scheduling Protocol --- p.26 / Chapter 4.3 --- Fundamental Limitation of LDS --- p.28 / Chapter 4.4 --- Chapter Conclusion --- p.31 / Chapter 5 --- Step-Establishing Algorithm --- p.33 / Chapter 5.1 --- Step-Establishing Algorithm --- p.33 / Chapter 6 --- "Performances of LDS, SRA, and SEA" --- p.45 / Chapter 6.1 --- Simulation --- p.45 / Chapter 6.2 --- Exponential Chain Topology --- p.46 / Chapter 6.3 --- Fixed-Transmission-Length Random Network --- p.47 / Chapter 6.4 --- Cluster Chain Topology --- p.50 / Chapter 6.5 --- General Random Network --- p.53 / Chapter 6.6 --- Running Time Complexity --- p.55 / Chapter 7 --- Conclusion --- p.60 / Chapter A --- Step-Removal Algorithm --- p.62 / Chapter A.1 --- Step-Removal Algorithm[1] --- p.62 / Chapter A.2 --- Illustration of the efficiency of SRA --- p.63 / Chapter B --- Low-Disturbance Scheduling Algorithm --- p.65 / Chapter B.1 --- Low-Disturbance Scheduling Algorithm --- p.65

Le, Jilin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 57-59). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- How Many Packets Can We Encode? --- p.2 / Chapter 1.2 --- Coding-Aware Routing --- p.3 / Chapter 2 --- Related Work --- p.6 / Chapter 3 --- Performance Analysis of COPE --- p.8 / Chapter 3.1 --- Introduction --- p.8 / Chapter 3.2 --- Coding Structure: Characterization and Properties --- p.9 / Chapter 3.2.1 --- Assumptions and notations --- p.9 / Chapter 3.2.2 --- Optimum Throughput in a Coding Structure --- p.10 / Chapter 3.2.3 --- The Upper Bound of Maximum Encoding Number --- p.11 / Chapter 3.3 --- Coding Performance under Random Access Link-Scheduling --- p.14 / Chapter 3.3.1 --- Key Intuition --- p.14 / Chapter 3.3.2 --- Calculating the Average Encoding Number --- p.15 / Chapter 3.3.3 --- Case Studies --- p.18 / Chapter 3.3.4 --- Will Delaying Strategy at the Coding Node Help? --- p.21 / Chapter 3.4 --- Fundamental Limits of the Coding Scheme --- p.22 / Chapter 3.5 --- Verification of the Analysis --- p.27 / Chapter 3.5.1 --- Simulation Results in a Single Coding Structure --- p.27 / Chapter 3.5.2 --- Simulation Results under 802.11 and General Networks --- p.29 / Chapter 3.6 --- Potential Applications --- p.31 / Chapter 3.7 --- Conclusion --- p.31 / Chapter 4 --- Distributed Coding-Aware Routing --- p.33 / Chapter 4.1 --- Introduction --- p.33 / Chapter 4.2 --- "The ""CodingH+Routing"" Discovery" --- p.34 / Chapter 4.2.1 --- Assumptions --- p.34 / Chapter 4.2.2 --- General Coding Conditions --- p.35 / Chapter 4.2.3 --- "Distributed ""Coding+Routing"" Discovery" --- p.36 / Chapter 4.2.4 --- An Illustrative Example --- p.38 / Chapter 4.2.5 --- Overheads of Coding+Routing Discovery --- p.39 / Chapter 4.3 --- Defining Coding-Aware Routing Metric --- p.40 / Chapter 4.3.1 --- Review of Current Routing Metrics --- p.40 / Chapter 4.3.2 --- Desirable Properties of Coding-aware Routing Metric --- p.42 / Chapter 4.3.3 --- Assumptions on Encoded Transmission --- p.42 / Chapter 4.3.4 --- "Interpreting the ""Free-Ride"" Benefit" --- p.43 / Chapter 4.3.5 --- Modified Queue Length --- p.44 / Chapter 4.3.6 --- MIQ: Modified Interference Queue Length --- p.46 / Chapter 4.3.7 --- CRM: Coding-aware Routing Metric --- p.47 / Chapter 4.4 --- Implementation Details --- p.48 / Chapter 4.5 --- Simulation Results --- p.49 / Chapter 4.5.1 --- Results from Illustrative Scenarios --- p.50 / Chapter 4.5.2 --- Results from Mesh Networks --- p.52 / Chapter 4.6 --- Conclusion --- p.55 / Chapter 5 --- Conclusion --- p.56 / Bibliography --- p.57

This thesis investigates the fundamental building blocks of physical-layer network coding (PNC). Most prior work on PNC focused on its application in a simple two-way-relay channel (TWRC) consisting of three nodes only. Studies of the application of PNC in general networks are relatively few. This thesis attempts to fill this gap by three steps: / In first step, we put forth two ideas: 1) A general network can be decomposed into small building blocks of PNC, referred to as the PNC atoms, for scheduling of PNC transmissions. 2) We identify nine PNC atoms, with TWRC being one of them. / In second step, we formulate the PNC scheduling problem as a linear program based on the atom-decomposition. Three major results are got from performance valuation: First, the throughput performance of PNC is shown to be significantly better than those of the traditional multi-hop scheme and the conventional network coding scheme. For example, under heavy traffic volume, PNC can achieve 100% throughput gain relative to the traditional multi-hop scheme. Second, PNC decomposition based on a variety of different PNC atoms can yield much better performance than PNC decomposition based on the TWRC atom alone. Third, three out of the nine atoms are most important to good performance. Specifically, the decomposition based on these three atoms is good enough most of the time, and it is not necessary to use the other six atoms. We have also designed a low-overhead MAC protocol to coordinate the transmissions of different nodes according to the scheduling results of PNC decomposition. / In third step, we investigate ARQ (Automatic Repeat request) designs for PNC systems (building blocks). The above building blocks studies assumed what is sent always get received. In practice, that is not the case. Error control is needed to ensure reliable communication. Here, we focus on the use of ARQ to ensure reliable PNC communication. In some of PNC building blocks, receivers can obtain side information through overhearing. Although such overheard information is not the target information that the receivers desire, the receivers can exploit the overheard information together with a network-coded packet received to obtain a desired native packet. This leads to throughput gain. The availability of overhead information and its potential exploitation make the ARQ design of a network-coded system different from that of a non-network-coded system. In this these, we lay out the fundamental considerations for such ARQ design: 1) We address how to track the stored coded packets and overheard packets to increase the chance of packet extraction, and derive the throughput gain achieved by tracking 2) We investigate two variations of PNC ARQ, coupled and non-coupled ARQs, and prove that non-coupled ARQ is more efficient; 3) We show how to optimize parameters in PNC ARQ—specifically the window size and ACK frequency—to minimize the throughput degradation caused by ACK feedback overhead and wasteful retransmissions due to lost ACK. Our throughput analyses and performance evaluations indicate that for our investigated atoms, our PNC ARQ yield considerable throughput gains. / In a conclusion, the decomposition based on a variety of different PNC atoms that we investigated can yield much better performance than the traditional multi-hop scheme and the conventional network coding scheme. In practical wireless systems where transmission errors can occur, adopting our PNC ARQ design can efficiently maintain the throughput gain achieved by PNC atom decomposition. / 本論文致力於研究基於物理層網絡編碼（PNC, Physical-layer Network Coding）的基礎構建模塊。現有的物理層網絡編碼的研究大都基於最簡單的雙向中繼信道（TWRC）系統上。TWRC是一個由三節點組成的小型通信網絡——兩個終端節點通過一個中繼節點通信。而基於大型網絡應用的PNC研究卻非常少見。為了填補這一空白，本論文分三步驟進行PNC研究: / 研究第一步，我們提出兩個問題： 1）為了PNC網絡調度，一個網絡可以被分解成若干小的PNC基礎構建模塊。 2）我們發現了除9個基本的PNC構建模塊（包含PNC TWRC）。 / 研究第二步，我們通過建立基於模塊分解的線性規劃方程來解決PNC網絡的調度問題。從性能評估中我們發現了三個重要結論： 第一，PNC分解的輸出效率遠高於傳統的多步傳輸和普通的網絡編碼傳輸。例如，在網絡運輸量很重的情況下，相比于傳統的多步傳輸，PNC分解傳輸可以取得100%輸出增益。第二，基於多種不同PNC模塊的分解傳輸，其效率高於只基於PNC TWRC的分解傳輸。第三，在我們研究的九個模塊中，三個模塊對輸出的貢獻最多。我們同時為PNC調度專門設計了介質訪問控制（MAC）的網絡協議。 / 研究第三步，我們研究了PNC系統的自動重傳請求（ARQ）設計。上述的PNC模塊研究假設了網絡的傳送總能被成功接收。但不符合實際的網絡狀況。需要採取錯誤控制來保護實際傳輸的穩定性。這裡，我們致力於研究用ARQ來保證PNC系統的穩定傳輸。在一些PNC模塊中，接受點可以利用旁聽到的信息包裹來解碼編碼過的包裹以獲得需要的自然包裹。這種對於旁聽信息的利用可以增加網絡的傳輸效率。同時也使PNC系統的ARQ設計不同於傳統網絡。在本論文中，我們列舉了三個基本的PNC ARQ設計原則： 1）我們強調了如何追蹤存儲的和旁聽到的信息包裹來增加提取有效包裹的機會并推導出了由此取得效率增益。 2）我們研究了兩種PNC ARQ系統，一種是綁定的ARQ，一種是非綁定的ARQ,并證明非綁定的ARQ效率更高。 3）我們展示了如何優化PNC ARQ的參數設置——傳輸窗口的大小和確認通知（ACK）的頻率——以最小化由ACK開銷和不必要的重傳引起的輸出損失。 / 總結來講，基於不同PNC模塊的網絡分解調度方法比傳統的多步傳輸方法和普通的網絡編碼傳輸更有效率。在實際的無線網絡中，當網絡傳輸出現錯誤時，採用我們的PNC自動重傳設計可以有效的保留PNC模塊分解所取得網絡增益。 / He, Jianghao. / Thesis Ph.D. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 126-128). / Abstracts also in Chinese. / Title from PDF title page (viewed on 24, October, 2016). / 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.

Xu, Ceng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 68-71). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.3 / Chapter 1.2 --- Contributions --- p.5 / Chapter 1.3 --- Thesis Scope --- p.5 / Chapter 2 --- Background Study --- p.6 / Chapter 2.1 --- Wireless Mesh Networks --- p.6 / Chapter 2.1.1 --- Overview of Wireless Mesh Networks --- p.6 / Chapter 2.1.2 --- Challenges of Wireless Mesh Networks --- p.9 / Chapter 2.1.3 --- Capacity Analysis of Wireless Mesh Net- works --- p.11 / Chapter 2.2 --- Network Coding --- p.13 / Chapter 2.2.1 --- Overview of Network Coding --- p.13 / Chapter 2.2.2 --- Network Coding in Wireless Networks --- p.17 / Chapter 3 --- Throughput Analysis --- p.19 / Chapter 3.1 --- Introduction --- p.19 / Chapter 3.2 --- Preliminaries --- p.20 / Chapter 3.3 --- Proof of Theorem 3.2.1 when n = m --- p.23 / Chapter 3.4 --- Proof of Theorem 3.2.1 when n≠ m --- p.36 / Chapter 3.4.1 --- Proof of Theorem 3.2.1 when m <n --- p.36 / Chapter 3.4.2 --- Proof of Theorem 3.2.1 when m > n --- p.37 / Chapter 3.5 --- Applying network coding into multi-radio multichannel networks --- p.37 / Chapter 3.6 --- Some simulation results --- p.40 / Chapter 3.6.1 --- String Topology --- p.40 / Chapter 3.6.2 --- Grid Topology --- p.41 / Chapter 3.6.3 --- Random Topology --- p.42 / Chapter 4 --- Interface Reduction in Wireless Mesh Networks --- p.43 / Chapter 4.1 --- Introduction --- p.43 / Chapter 4.2 --- Preliminaries --- p.44 / Chapter 4.2.1 --- Assumptions and Objectives of the Algorithm --- p.44 / Chapter 4.2.2 --- Definitions --- p.45 / Chapter 4.3 --- Steps of the Algorithm and an Example --- p.49 / Chapter 4.4 --- Simulation Results and Discussions --- p.53 / Chapter 4.5 --- Generalization --- p.54 / Chapter 5 --- Conclusion --- p.66 / Bibliography --- p.68

The prevalence of wireless networks is on the increase. Society is becoming increasingly reliant on ubiquitous computing, where mobile devices play a key role. The use of wireless networking is a natural solution to providing connectivity for such devices. However, the availability of infrastructure in wireless networks is often limited. Such networks become dependent on wireless ad hoc networking, where nodes communicate and form paths of communication themselves. Wireless ad hoc networks present novel challenges in contrast to fixed infrastructure networks. The unpredictability of node movement and route availability become issues of significant importance where reliability is desired.To improve reliability in wireless ad hoc networks, predicting future connectivity between mobile devices has been proposed. Predicting connectivity can be employed in a variety of routing protocols to improve route stability and reduce unexpected drop-offs of communication. Previous research in this field has been limited, with few proposals for generating future predictions for mobile nodes. Further work in this field is required to gain a better insight into the effectiveness of various solutions.This thesis proposes such a solution to increase reliability in wireless ad hoc routing. This research presents two novel concepts to achieve this: the Communication Map (CM), and the Future Neighbours Table (FNT). The CM is a signal loss mapping solution. Signal loss maps delineate wireless signal propagation capabilities over physical space. With such a map, connectivity predictions are based on signal capabilities in the environment in which mobile nodes are deployed. This significantly improves accuracy of predictions in this and in previous research. Without such a map available, connectivity predictions have no knowledge of realistic spatial transmission ranges. The FNT is a solution to provide routing algorithms with a predicted list of future periods of connectivity between all nodes in an established wireless ad hoc network. The availability of this information allows route selection in routing protocols to be greatly improved, benefiting connectivity. The FNT is generated from future node positional information combined with the CM to provide predicted signal loss estimations at future intervals. Given acceptable signal loss values, the FNT is constructed as a list of periods of time in which the signal loss between pairs of nodes will rise above or fall below this acceptable value (predicted connectivity). Future node position information is ideally found in automated networks. Robotic nodes commonly operate where future node task movement is developed and planned into the future, ideal for use in predicted connectivity. Non-automated prediction is also possible, as there exist some situations where travel paths can be predictable, such as mobile users on a train or driving on a highway. Where future node movement is available, predictions of connectivity between nodes are possible.

Spread ALOHA has become one of the advanced multiple access techniques promising several advantages over existing conventional and spread spectrum based wireless systems. Spread ALOHA is currently recognised as a simplified wireless multiple access system which provides a higher bandwidth and may accommodate high number of users. This thesis investigates the employment of a unique spreading code in conjunction with Spread ALOHA as opposed to the common method of employing distinct spreading codes for all users on the communication channel. This feature of Spread ALOHA would eliminate the limitation on the number of users imposed by finding sufficient orthogonal spreading codes, and moreover it would simplify the system and reduce the receiver complexity. In this research I have investigated the state of the art on this topic, and I have modelled and simulated a Single Code Spread ALOHA system together with a conventional CDMA ALOHA system in order to analyse and compare the performance of both systems. This study has shown the viability of employing single code in Spread ALOHA systems, and hence eliminating what is considered a limiting factor in other systems such as CDMA. The performance of this proposed system is comparable with that of CDMA; however the selection of suitable PN codes is essential. The parametric study in this work was aimed to find optimum performance criteria for the Spread ALOHA system. all users on the spread spectrum system to have equal average; received power levels. / Master of Engineering (Hons)

Advances in wireless networking technology have engendered a new paradigm of computing, called mobile computing; in which users carrying portable devices have access to a shared infrastructure independent of their physical location. Mobile computing has matured rapidly as a field of computer science. In environments of mobile computing, the mobility and disconnection of portable computing devices introduce many new challenging problems that have never been encountered in conventional computer networks. New research issues combine different areas of computer science: networking, operating systems, data and knowledge management, and databases. This thesis studies data and knowledge transaction in mobile environments. To study transaction processing at the fundamental and theoretical level in mobile environments, a range of classical notions and protocols of transaction processing are rechecked and redefined in this thesis, and form the foundation for studying transaction processing in mobile environments. A criterion for mobile serial history is given and two new concurrency theorems are proved in mobile environments. In addition to data transaction, this thesis explores knowledge transaction in mobile environments. To study knowledge transaction in mobile environments this thesis presents and formalizes a knowledge transaction language and model for use in mobile computing environments. The thesis further formalizes a framework/model for a mobile logic programming multi-agent system which can be used to study knowledge transaction in multi-agent systems in mobile environments and is a very early effort towards a formal study of knowledge base and intelligent agents in mobile environments. This work provides a foundation for the formal specification and development of real-world mobile software systems, in the same way as traditional software systems have developed. / Doctor of Philosophy (PhD) (Science)