因為今天四通八達的無線通信網絡對高速高質量通信的要求,加之無線通信資源的稀缺,使得資源分配在無線通信領域的地位越發的重要.多種多樣的無線通信資源和不同的設計要永使得資源分配問題變得很複雜,我們也很難找到一個通用的方法去解決所有的資源分配問題.在本文中, 我們研究一些典型的資源分配問題,通過最優化設計,給出恰當的高效的算法予以解決.本文中將會涉及集中化算法和分佈式算法。 / 在本文中, 我們首先研究協作通信中的功率分配和中繼選擇問題。這個問題因為其問題的組合性而變得很複雜。為了保證系統的性能並且同時避免過量的冗餘信息, 我們提出了一個新的概念"中繼選擇自由度"。更重要的是, 為了使我們的方法能夠適用於集中信息很難的大型通信系統, 我們提出了分佈式的解決方案。該方法在實際中可以比較簡單的實現。 / 我們接著研究多用戶接入網絡的"軟"服務質量控制問題。我們這裡考慮的情形是:用戶們有各自的服務質量要求, 比如有一個目標速率。因為系統的資源總是有限的, 如果有過多用戶, 那麼同時滿足所有用戶的服務質量要求有時候是不可能的。我們的目標是在這種情況發生的時候,優化整個系統的資源分配。我們提出了分佈式算法來解決這一個問題。 / 最後, 我們研究下行鏈中的波束成形問題。這裡我們出於實際情況考慮,系統中存在兩種用戶:優先用戶和非優先用戶。我們想要盡可能最大化的提升非優先用戶的性能,同時必須首先滿足優先用戶的服務質量用要求。我們這裡用不同的波束成形向量來完成這個任務。這個問題是NP問題,我們做了必要的一些放鬆處理來得到有效的較優的解。 / Due to the limited resources and high performance requirements in today’s wireless networks, optimization methods in resource allocation play a significant role in reaping the benefits from wireless communications. Various available resources and different design goals make the resource allocation problem complex and we are unlikely to find a generic approach for all problems. Thus in this thesis, we investigate several resource allocation problems and propose the proper optimization methods and algorithms that can efficiently give us desired solutions. Also, both centralized and distributed methods will be shown in this thesis. / We first study the joint power allocation and relay selection problem in cooperative communication. This problem is complex due to its combinatorial nature. In order to avoid high information overhead and system complexity while at the same time maintain system performance, we introduce a new concept called “relay selection degree bound“. Moreover, since in large scale cooperative communication network, collecting information and centralized control would be very difficult, we resort to distributed algorithms that can be easily implemented in practice. / We further consider the soft QoS control problem in multiple access network. Here we consider the situation where the users have quality of service(QoS) requirements, i.e., each user has a target rate for its application. Since the resources in the system are limited, these requirements will result in the infeasibility of the whole system if there are too many users. We aim at optimizing the performance of the whole system while this kind of infeasibility happens. We will see how distributed algorithms can work for this problem and give us desired results. / We finally consider the downlink beamforming problem where there are two kind of users in the system: priority users and non-priority users. We maximize the non-priority users performance while at the same time satisfying the priority users’ QoS requirements first. Here we adopt heterogeneous beamforming scheme to complete the task. Since the problem is NP hard, relaxation is done for efficient solutions. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Fang, Haoran. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 76-81). / Abstracts also in Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / 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.9 / Chapter 1.3 --- Outline of the Thesis --- p.11 / Chapter 2 --- Resource Allocation for Cooperative Communication Networks --- p.13 / Chapter 2.1 --- Chapter Introduction --- p.13 / Chapter 2.2 --- system model and problem formulation --- p.16 / Chapter 2.3 --- optimal power allocation scheme for arbitrary configuration --- p.20 / Chapter 2.4 --- Relay selection in the MAC layer --- p.24 / Chapter 2.4.1 --- Algorithm Design --- p.24 / Chapter 2.4.2 --- Distributed Implementation of The Relay Selection Algorithm --- p.29 / Chapter 2.5 --- Numerical Results --- p.33 / Chapter 2.5.1 --- The Convergence of Distributed Power Allocation Algorithm --- p.33 / Chapter 2.5.2 --- Performance of The Overall Cross Layer Solution --- p.34 / Chapter 2.5.3 --- Improvements of Heuristic Markov algorithm --- p.36 / Chapter 2.6 --- Chapter Conclusions --- p.38 / Chapter 3 --- Soft QoS Control in Multiple Access Network --- p.39 / Chapter 3.1 --- Introduction --- p.39 / Chapter 3.2 --- system model --- p.41 / Chapter 3.3 --- Feasibility check and soft QoS control --- p.43 / Chapter 3.3.1 --- Feasibility Check --- p.43 / Chapter 3.3.2 --- Soft QoS Control --- p.45 / Chapter 3.3.3 --- Distributed Soft QoS Control --- p.47 / Chapter 3.3.4 --- Numerical Results --- p.53 / Chapter 3.4 --- Chapter Conclusion --- p.57 / Chapter 4 --- Heterogeneous resource allocation via downlink beamforming --- p.58 / Chapter 4.1 --- Introduction --- p.58 / Chapter 4.2 --- system model --- p.60 / Chapter 4.3 --- heterogeneous resource allocation via beamforming --- p.62 / Chapter 4.3.1 --- Relaxation and problem analysis --- p.62 / Chapter 4.3.2 --- Randomization for final solutions --- p.66 / Chapter 4.4 --- Numerical Results --- p.69 / Chapter 4.5 --- Conclusion --- p.70 / Chapter 5 --- Conclusions and Future Work --- p.73 / Chapter 5.1 --- Conclusions --- p.73 / Chapter 5.2 --- Future Work --- p.74 / Bibliography --- p.76

Yuan, Yan. / Thesis submitted in: November 2007. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 84-87). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Wireless Mesh Network --- p.3 / Chapter 1.1.1 --- Architecture Overview --- p.3 / Chapter 1.1.2 --- Routing Protocols --- p.5 / Chapter 1.2 --- Contribution of this Thesis --- p.7 / Chapter 1.3 --- Organization of this Thesis --- p.8 / Chapter 2 --- Background and Literature Review --- p.9 / Chapter 2.1 --- VoIP on Wireless Mesh Networks --- p.9 / Chapter 2.1.1 --- Performance of VoIP on Wireless Mesh Networks --- p.9 / Chapter 2.1.2 --- Optimizations for VoIP over Wireless Mesh Networks --- p.12 / Chapter 2.1.3 --- Path and Packet Aggregation Scheme --- p.14 / Chapter 2.2 --- Network Coding on Wireless Mesh Networks --- p.15 / Chapter 2.2.1 --- The Concept of Network Coding --- p.15 / Chapter 2.2.2 --- Related Work --- p.16 / Chapter 3 --- Adaptive Path and Packet Aggregation System --- p.19 / Chapter 3.1 --- Overview --- p.19 / Chapter 3.2 --- The Adaptive Path Aggregation Routing Algorithm --- p.20 / Chapter 3.2.1 --- Protocol Overview --- p.20 / Chapter 3.2.2 --- Data Structure --- p.21 / Chapter 3.2.3 --- The Concept of Link Weight and Path Weight --- p.26 / Chapter 3.2.4 --- APA Operations --- p.27 / Chapter 3.3 --- The Packet Aggregation System --- p.39 / Chapter 3.3.1 --- Overview --- p.39 / Chapter 3.3.2 --- Packet structure --- p.40 / Chapter 3.3.3 --- Local Compression --- p.41 / Chapter 3.3.4 --- Packet Aggregation/Disaggregation --- p.42 / Chapter 3.4 --- Performance Analysis --- p.44 / Chapter 3.4.1 --- Integration of the path aggregation routing protocol and the packet aggregation system --- p.46 / Chapter 3.5 --- Performance Evaluation --- p.48 / Chapter 3.5.1 --- Testbed Setup --- p.48 / Chapter 3.5.2 --- Packet aggregation --- p.48 / Chapter 3.5.3 --- Combined scenario: path and packet aggregation --- p.58 / Chapter 3.6 --- Summary --- p.65 / Chapter 4 --- Network Coding System in wireless network --- p.67 / Chapter 4.1 --- Overview --- p.67 / Chapter 4.2 --- System Architecture --- p.68 / Chapter 4.2.1 --- Packet Format --- p.68 / Chapter 4.2.2 --- Encoding and decoding --- p.69 / Chapter 4.3 --- Performance Evaluation --- p.71 / Chapter 4.3.1 --- Experiment Setup --- p.71 / Chapter 4.3.2 --- Performance Metric --- p.72 / Chapter 4.3.3 --- Experiment Results --- p.72 / Chapter 4.4 --- Summary --- p.79 / Chapter 5 --- Conclusions and Future Directions --- p.82

published_or_final_version / abstract / Electrical and Electronic Engineering / Master / Master of Philosophy

published_or_final_version / abstract / Electrical and Electronic Engineering / Master / Master of Philosophy

From wirelessly connected robots to car-to-car communications, and to smart cities, almost every aspect of our lives will benefit from future wireless communications. While promise an exciting future world, next-generation wireless communications impose requirements on the data rate, spectral efficiency, and latency (among others) that are higher than those for today's systems by several orders of magnitude. Full-duplex wireless, an emergent wireless communications paradigm, breaks the long-held assumption that it is impossible for a wireless device to transmit and receive simultaneously at the same frequency, and has the potential to immediately double network capacity at the physical (PHY) layer and offers many other benefits (such as reduced latency) at the higher layers. Recently, discrete-component-based demonstrations have established the feasibility of full-duplex wireless. However, the realization of integrated full duplex radios, compact radios that can fit into smartphones, is fraught with fundamental challenges. In addition, to unleash the full potential of full-duplex communication, a careful redesign of the PHY layer and the medium access control (MAC) layer using a cross-layer approach is required. The biggest challenge associated with full duplex wireless is the tremendous amount of transmitter self-interference right on top of the desired signal. In this dissertation, new self-interference-cancellation approaches at both system and circuit levels are presented, contributing towards the realization of full-duplex radios using integrated circuit technology. Specifically, these new approaches involve elimination of the noise and distortion of the cancellation circuitry, enhancing the integrated cancellation bandwidth, and performing joint radio frequency, analog, and digital cancellation to achieve cancellation with nearly one part-per-billion accuracy. In collaboration with researchers at higher layers of the stack, a cross-layer approach has been used in our full-duplex research and has allowed us to derive power allocation algorithms and to characterize rate-gain improvements for full-duplex wireless networks. To enable experimental characterization of full-duplex MAC layer algorithms, a cross-layered software-defined full-duplex radio testbed has been developed. In collaboration with researchers from the field of micro-electro-mechanical systems, we demonstrate a multi-band frequency-division duplexing system using a cavity-filter-based tunable duplexer and our integrated widely-tunable self-interference-cancelling receiver.

協作多點 (CoMP)是一種最近興起的傳輸技術，其主要作用為應付新一代無線通訊系統中的小區間干擾問題。在過去十數年內，研究員研發了 CoMP中一些關鍵的新技術，當中包括 MIMO合作和干擾協調。本論文考慮一個聯合用戶排程和干擾協調的問題。在傳統的研究中，用戶排程和干擾協調通常作為獨立的問題進行研究。可是，從本質上這兩個問題是相互影響的，因此傳統的研究將導致系統性能退化。為此，本論文探討了一個聯合用戶排程和波束形成（JACoB）的問題，這當中採用了一種稱為協同波束形成（CoBF）的干擾協調技術。具體而言，本文把 JACoB問題表達成了一個可支持用戶數最大化的問題，而其中的 CoBF設計將盡可能地配合用戶的需求而改變。 / 本論文有兩個主要的貢獻。第一，本文把 JACoB問題轉換成一個 ℓ₀範數最小化問題。其後本文採用 ℓ₁範數近似法將 JACoB問題近似為一個凸優化問題。第二，本文提出一種新型的分佈 JACoB方法。本文提出的分佈方法是基於塊坐標下降法。該方法不同於傳統的基於次梯度方法的分佈方法，如原始/對偶分解。 / 仿真結果顯示，採用本文提出的 JACoB方法（無論是集中的或是分佈的）所能支持的用戶數量遠超過現有的固定波束形成方法。此外，本文提出的分佈 JACoB方法能達到與集中JACoB方法相近的性能，而且其收斂速度亦是相當快的。 / Coordinated MultiPoint (CoMP) cooperative transmission has recently emerged as a promising technique for mitigating intercell interference in next generation wireless communication systems. Several key techniques for CoMP have been endeavored over the past decades, for example, MIMO cooperation and interference coordination. The present work studies a joint user scheduling and interference coordination problem in the CoMP downlink systems. Conventionally, user scheduling and interference coordination are treated as separate problems. This may result in a degradation of the system performance as the two problems are actually intertwined with each other. As such, this thesis considers a joint admission control and beamforming (JA-CoB) problem which employs a popular interference coordination technique called coordinated beamforming (CoBF). In particular, the JA-CoB problem is stated as a user number maximization problem where the CoBF design can be adapted to the set of selected users. / There are two major contributions in this thesis. Firstly, the JA-CoB problem is cast as an ℓ₀ norm minimization problem and then tackled by the now popularized ℓ₁ approximation technique. Secondly, a novel decentralized JACoB method is developed. The proposed de-centralized method is based on the simple block coordinate descent method, which is different from the conventional approaches which em-ploy subgradient-based method such as dual/primal decomposition. / The simulation results indicate that: i) the proposed centralized method yields a performance close to the optimum JACoB design while the complexity is significantly reduced; ii) employing the proposed JA-CoB methods (either centralized or decentralized) gives a significant gain over a fixed beamformers design in terms of the number of supported users. Moreover, the decentralized JACoB method achieves a performance close to its centralized counterpart, whilst the convergence speed is considerably fast. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wai, Hoi To. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 77-80). / Abstracts also in Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview of techniques for CoMP --- p.2 / Chapter 1.2 --- Overview of user scheduling algorithms --- p.4 / Chapter 1.3 --- Contributions --- p.6 / Chapter 2 --- The JACoB problem and the related works --- p.8 / Chapter 2.1 --- System model --- p.8 / Chapter 2.2 --- Joint admission control and beamforming (JACoB) --- p.10 / Chapter 2.2.1 --- Coordinated beamformers design --- p.11 / Chapter 2.2.2 --- Semide nite relaxation for the CoBF problem --- p.13 / Chapter 2.3 --- Related works --- p.14 / Chapter 2.3.1 --- Common trend in JACoB - deflation heuristic . --- p.18 / Chapter 2.4 --- Decentralized methods --- p.19 / Chapter 3 --- Centralized JACoB method --- p.21 / Chapter 3.1 --- Step 1 - a new formulation to JACoB --- p.21 / Chapter 3.2 --- Step 2 - ℓ₁ approximation to JACoB --- p.24 / Chapter 3.2.1 --- Properties of the ℓ₁ JACoB problem --- p.26 / Chapter 3.3 --- Proposed JACoB method --- p.28 / Chapter 3.3.1 --- Prescreening procedure --- p.28 / Chapter 4 --- Decentralized JACoB method --- p.31 / Chapter 4.1 --- Block coordinate descent method --- p.32 / Chapter 4.2 --- Smooth approximation to ℓ₁ JACoB --- p.34 / Chapter 4.2.1 --- Empirical iteration complexity of the BCD method --- p.38 / Chapter 4.3 --- Proposed decentralized JACoB method --- p.40 / Chapter 5 --- Simulation results --- p.43 / Chapter 5.1 --- Performance of centralized JACoB methods --- p.44 / Chapter 5.2 --- Performance of decentralized JACoB methods --- p.48 / Chapter 5.3 --- Summary --- p.52 / Chapter 6 --- Conclusions and future directions --- p.53 / Chapter 6.1 --- Future directions --- p.53 / Chapter 6.1.1 --- From a practical point of view --- p.54 / Chapter 6.1.2 --- From a theoretical point of view --- p.54 / Chapter A --- A primal decomposition method for (3.4) --- p.56 / Chapter B --- A projected gradient method for (4.3) --- p.60 / Chapter C --- Proofs --- p.67 / Chapter C.1 --- KKT conditions for (2.6) and (3.5) --- p.67 / Chapter C.2 --- Proof of Proposition 2.1 --- p.68 / Chapter C.3 --- Proof of Proposition 3.3 --- p.69 / Chapter C.4 --- Proof of Proposition 3.2 --- p.69 / Chapter C.5 --- Proof of Proposition 3.5 --- p.71 / Chapter C.6 --- Proof of Fact 4.1 --- p.75 / Bibliography --- p.77

The determination of the optimal location of transceivers is a critical design factor when deploying a wireless local area network (WLAN). The performance of the WLAN will improve in a variety of aspects when the transceivers' locations are adequately determined, including the overall cell coverage to the battery life of the client units. Currently, the most common method to determine the appropriate location of transceivers is known as a site survey, which is normally a very time and energy consuming process. The main objective of this research was to improve current methodologies for the optimal or near-optimal placement of APs in a WLAN installation. To achieve this objective, several improvements and additions were made to an existing computational tool to reflect the evolution that WLAN equipment has experienced in recent years. Major additions to the computational tool included the addition of the capability to handle multiple power levels for the transceivers, the implementation of a more adequate and precise representation of the passive interference sources for the path loss calculations, and the definition of a termination criterion to achieve reasonable computational times without compromising the quality of the solution. An experiment was designed to assess how the improvements made to the computational tool provided the desired balance between computational time and the quality of the solutions obtained. The controlled factors were the level of strictness of the termination criterion (i.e., high or low), and the number of runs performed (i.e., 1, 5, 10, 15, and 20 runs). The low level of strictness proved to dramatically reduce (i.e., from 65 to 70%) the running time required to obtain an acceptable solution when compared to that obtained at the high level of strictness. The quality of the solutions found with a single run was considerably lower than that obtained with the any other number of runs. On the other hand, the quality of the solutions seemed to stabilize at and after 10 runs, indicating that there is no added value to the quality of the solution when 15 or 20 runs are performed. In summary, having the computational tool developed in this research execute 5 runs with the low level of strictness would generate high quality solutions in a reasonable running time. / Graduation date: 2004

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

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