本文研究在物理層網絡編碼（PNC）系統和多用戶檢測（MUD）系統中的聯合多參數估計與信道譯碼問題。PNC 與MUD 都是從多個用戶的同時信號傳輸中獲利的技術。然而，多個同時傳輸信號的迭加也對信號處理帶來了若干挑戰。首先一個挑戰是在接收機處的多參數估計問題。另外一個挑戰是，如何同時補償多個參數。本文包括兩部分，每一部分的貢獻分別是在PNC 或MUD 系統中，針對上述問題的解決方案。 / 第一部分: 在本文的第一部分中，我們解決在PNC 系統中的聯合信道估計與信道譯碼問題。在PNC 系統中，多個用戶同時給中繼傳輸信號。PNC 系統的信道譯碼不同於傳統的多用戶系統的信道譯碼。具體地，中繼的目標是譯碼出網絡編碼後的信息而非單獨的每個源信息。雖然之前的研究工作顯示PNC 可以很大程度上提高中繼網絡的吞吐量，但是這個提高的前提假設是能夠獲得精確的信道估計。然而，因為以下原因，PNC系統中的信道估計尤其具有挑戰性：1）多個用戶的信號迭加在一起；2）信道編碼使得數據符號之間非獨立；3）信道是時變的。為解決這些難題，我們將expectation-maximization（EM）算法和belief propagation（BP）算法結合在一個統一的factor graph 框架之下。在這個factor graph 框架下，信道估計由EM subgraph 完成，信道譯碼由建模了和PNC 信道譯碼目標相匹配的虛擬編碼器的BP subgraph 完成。在兩個subgraph 的迭代消息傳輸使得我們可以逐漸逼近信道估計和信道譯碼的最優解。我們提供了大量的模擬結果來說明我們所提出方案的優越性。 / 第二部分: 在本文的第二部分中，我們研究了一個信道編碼的多用戶檢測（MUD）系統。該系統是基於正交頻分複用（OFDM）調製和交織分多址接入（IDMA）技術的。將OFDM與IDMA結合的動機是其可以在頻率選擇多址接入信道環境下獲得多用戶分集增益的能力。然而，為了實現這個能力，我們必須首先解決由多個載波頻率偏移（CFO）所引起的頻率異步問題。論文本部分解決如下挑戰。首先的挑戰是多信道參數（CFO，信道增益等）的估計。考慮到各個用戶的參數估計問題互相影響而導致總的參數估計誤差會隨用戶數目而增長，一個具體地難題是如何克制多個用戶多個參數的估計誤差。第二個挑戰是如何補償多個CFO。一個具體的難題是，不同於只存在一個CFO 的單用戶接收機，我們的多用戶接收機不可能同時補償多個不同的CFO。為解決以上兩個挑戰，我們提出了在一個多用戶系統中聯合、迭代解決多信道參數估計、CFO 補償和信道譯碼的框架。該框架利用了space alternating generalized expectation-maximization（SAGE）算法和expectation-conditional maximization （ECM）算法。我們的研究揭示，在ECM 算法中，將數據符號而非信道參數設置為hidden data 將導致更好的系統性能。進一步地，我們用Gaussian message passing 技術將算法複雜度有效降低。計算機仿真和軟件無線電平臺上的真實實驗表明，和傳統多用戶方法相比，我們方法能獲得非常高的性能增益。 / 總體來說，本文提出了兩個算法框架（EM-BP，SAGE-ECM）來解決聯合多參數估計和信道解碼問題。我們相信，針對多用戶系統中多個信號疊加而帶來的信號處理挑戰，我們所提算法框架是非常具有前景的解決方案。 / This thesis investigates the joint multiple parameter estimation and channel decoding problem for physical-layer network coding (PNC) and multiuser detection (MUD) systems. Both of PNC and MUD can take advantages from the simultaneous transmissions by multiple users. However, the superimposition of multiple transmissions brings with it new challenges for signal processing. The first major challenge is the estimation of the multiple parameters at the receiver. The second major challenge is how to compensate for system impairments caused by these parameters. This thesis consists of two parts that tackle these challenges: The first part is related to PNC systems and the second part is related to MUD systems. / Part I: The first part of this thesis addresses the problem of joint channel estimation and channel decoding in PNC systems. In PNC, multiple users transmit to a relay simultaneously. PNC channel decoding is different from conventional multiuser channel decoding: Specifically, the PNC relay aims to decode a network-coded message rather than the individual messages of the users. Although prior work has shown that PNC can significantly improve the throughput of a relay network, the improvement is predicated on the availability of accurate channel estimates. Channel estimation in PNC, however, can be particularly challenging because of 1) the overlapped signals of multiple users; 2) the correlations among data symbols induced by channel coding; and 3) time-varying channels. We combine the expectation-maximization (EM) algorithm and belief propagation (BP) algorithm on a unified factor-graph framework. In this framework, channel estimation is performed by an EM subgraph, and channel decoding is performed by a BP subgraph that models a virtual encoder matched to the target of PNC channel decoding. Iterative message passing between these two subgraphs allows the optimal solutions for both to be approached progressively. We present extensive simulation results demonstrating the superiority of our PNC receivers over other PNC receivers. / Part II: The second part of this thesis investigates a channel-coded MUD system operated with orthogonal frequency division multiplexing (OFDM) and interleaved division multiple-access (IDMA). In general, there are many variations to MUD systems. Our choice of the combination of OFDM and IDMA is motivated by its ability to achieve multiuser diversity gain in frequency-selective multiple-access channels. However, to realize this potential advantage of OFDM-IDMA, we must first solve the frequency asynchrony problem induced by the multiple carrier frequency offsets (CFOs) of the signals of multiple users. This part of the thesis tackles the following two major challenges. The first, as in PNC systems, is the estimation of multiple channel parameters (e.g., CFOs and channel gains). A particular challenge is how to contain the estimation errors of the channel parameters of the multiple users, considering that the overall estimation errors may increase with the number of users because the estimations of their channel parameters are intertwined with each other. The second is how to compensate for the multiple CFOs. A particular difficulty is that, different from a single-user receiver for which there is only one CFO, it is not possible for our multiuser receiver to compensate for all the multiple CFOs simultaneously. To tackle the two challenges, we put forth a framework that solves the joint problem of multiuser channel-parameter estimation, CFO compensation, and channel decoding iteratively by employing the space alternating generalized expectation-maximization (SAGE) and expectation-conditional maximization (ECM) algorithms. Our study reveals that treating the data rather than the channel parameters as the hidden data in ECM will lead to better performance. We further show that Gaussian message passing is an effective complexity reducing technique. Simulations and real experiments based on software-defined radio (SDR) indicate that, compared with other approaches, our approach can achieve significant performance gains. / Overall, this thesis puts forth two frameworks (EM-BP for PNC, SAGE-ECM for MUD) to address the problem of multiple parameter estimation and channel decoding. We believe our frameworks are promising solutions for the signal processing challenges arising from the superimposition of multiple transmissions in multiuser systems. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wang, Taotao. / Thesis (Ph.D.) Chinese University of Hong Kong, 2015. / Includes bibliographical references (leaves 157-168). / Abstracts also in Chinese.

Fong, Yiu Leung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 83-87). / Abstracts in English and Chinese. / Abstract --- p.2 / Acknowledgement --- p.6 / Chapter 1. --- Introduction --- p.9 / Chapter 2. --- Background and Motivation --- p.10 / Chapter 2.1 --- Context-Based Arithmetic Coding --- p.10 / Chapter 2.2 --- Video Post-processing --- p.13 / Chapter 3. --- Context-Based Arithmetic Coding for JPEG --- p.16 / Chapter 3.1 --- Introduction --- p.16 / Chapter 3.1.1 --- Huffman Coding --- p.16 / Chapter 3.1.1.1 --- Introduction --- p.16 / Chapter 3.1.1.2 --- Concept --- p.16 / Chapter 3.1.1.3 --- Drawbacks --- p.18 / Chapter 3.1.2 --- Context-Based Arithmetic Coding --- p.19 / Chapter 3.1.2.1 --- Introduction --- p.19 / Chapter 3.1.2.2 --- Concept --- p.20 / Chapter 3.2 --- Proposed Method --- p.30 / Chapter 3.2.1 --- Introduction --- p.30 / Chapter 3.2.2 --- Redundancy in Quantized DCT Coefficients --- p.32 / Chapter 3.2.2.1 --- Zig-Zag Scanning Position --- p.32 / Chapter 3.2.2.2 --- Magnitudes of Previously Coded Coefficients --- p.41 / Chapter 3.2.3 --- Proposed Scheme --- p.43 / Chapter 3.2.3.1 --- Overview --- p.43 / Chapter 3.2.3.2 --- Preparation of Coding --- p.44 / Chapter 3.2.3.3 --- Coding of Non-zero Coefficient Flags and EOB Decisions --- p.45 / Chapter 3.2.3.4 --- Coding of ´بLEVEL' --- p.48 / Chapter 3.2.3.5 --- Separate Coding of Color Planes --- p.53 / Chapter 3.3 --- Experimental Results --- p.54 / Chapter 3.3.1 --- Evaluation Method --- p.54 / Chapter 3.3.2 --- Methods under Evaluation --- p.55 / Chapter 3.3.3 --- Average File Size Reduction --- p.57 / Chapter 3.3.4 --- File Size Reduction on Individual Images --- p.59 / Chapter 3.3.5 --- Performance of Individual Techniques --- p.63 / Chapter 3.4 --- Discussions --- p.66 / Chapter 4. --- Video Post-processing for H.264 --- p.67 / Chapter 4.1 --- Introduction --- p.67 / Chapter 4.2 --- Proposed Method --- p.68 / Chapter 4.3 --- Experimental Results --- p.69 / Chapter 4.3.1 --- Deblocking on Compressed Frames --- p.69 / Chapter 4.3.2 --- Deblocking on Residue of Compressed Frames --- p.72 / Chapter 4.3.3 --- Performance Investigation --- p.74 / Chapter 4.3.4 --- Investigation Experiment 1 --- p.75 / Chapter 4.3.5 --- Investigation Experiment 2 --- p.77 / Chapter 4.3.6 --- Investigation Experiment 3 --- p.79 / Chapter 4.4 --- Discussions --- p.81 / Chapter 5. --- Conclusions --- p.82 / References --- p.83

Han, Qinglong. / Thesis Ph.D. Chinese University of Hong Kong 2016. / Includes bibliographical references (leaves 141-148). / Abstracts also in Chinese. / Title from PDF title page (viewed on 25, October, 2016).

With the integration of wireless technologies and multimedia services, transmitting high quality images and video has become one of the main objectives for next generations mobile network systems. Shannon's classic separation theorem states that, under ideal conditions, source coding and channel coding can be treated separately without sacrificing any performance for the whole system. However, this theorem holds true only under ideal conditions. Practical communication systems do not meet such requirements. Therefore, joint source and channel coding may reduce distortion, as well as complexity and delay. In this thesis, different schemes of joint source-channel coding and decoding for error resilient image transmission over noisy channels are examined. Unequal error protection (UEP) is one of the techniques used in joint source and channel coding. A JPEG image is partitioned into DC components and AC components according to their respective sensitivity to channel noise. The highly sensitive DC components are better protected with a low coding rate, while the less sensitive AC components use a high coding rate. Simulation results show that the proposed UEP scheme slightly outperforms conventional equal error protection (EEP). A novel turbo diversity scheme (TDS) applied to JPEG coded images is proposed. Turbo codes have a built-in structure that is suitable for diversity techniques used to improve the quality of communications over a multi-path channel. The same image data is encoded by two separate turbo encoders and sent over two independent channels. The received data is then passed to a single turbo decoder. By utilising the built-in structure of the turbo encoder, the transmitted JPEG data encoded by a rate half code is recovered at the receiver using a more powerful rate third code yielded by the TDS. An iterative source-channel decoding scheme applied to JPEG coded images is investigated. Huffman codes used as the variable-length coding scheme in JPEG coding can be represented by an irregular VLC-trellis structure. State transition probabilities can be derived from the irregular trellis and can be used as a priori information to help iterative decoding between source and channel a posteriori probability (APP) decoders. Iterative decoding of JPEG coded images only gives a small coding gain due to the poor distance property of the original JPEG Huffman codes. We propose to replace the Huffman codes used in JPEG coding with error resilient source codes with larger free distance. After accounting for the penalty due to the increased average codeword length, the new scheme achieves a 4 dB coding gain over the conventional system for a range of SNRs. While the focus of this thesis is on joint source-channel coding, two other related topics are also examined, namely, capacity and normalisation of intersymbol interference (ISI) channels and parallel data convolutional codes. Previously published results showed a minimum Eb/N0 of -4.6 dB, 3 dB below the capacity of a flat channel, is obtained using the water-pouring capacity formulas for the 1+D channel. However, these results did not take into account that the channel power gain can be greater than unity when water-pouring is used. We present a new generic power normalization method of ISI channel frequency spectra, namely peak bandwidth normalisation, to facilitate the fair capacity comparison of various ISI channels. A final contribution presented in this thesis regards the proposed parallel data convolutional codes (PDCCs). The encoder inputs consist of the original block of data and its interleaved version. We propose a novel single self-iterative soft-input/soft-output (SISO) decoder structure for the decoding of PDCC. It has the advantage of needing only one APP decoder. Although the performance is not very encouraging, the novelty of the self-iterative idea behind the design is worth exploiting. / thesis (PhDTelecommunications)--University of South Australia, 2003.

We investigate, improve and develop speech analysis techniques which can be used to enhance various speech processing systems, especially low bit rate or variable bit rate coding of speech. The coding technique based on the sinusoidal representation of speech is investigated and implemented. Based on this study of the sinusoidal model of speech, improved analysis techniques to determine voicing, pitch and spectral estimation are developed, as well as noise reduction technique. We investigate the properties and limitations of the spectral envelope estimation vocoder (SEEVOC). We generalize, optimize and improve the SEEVOC and also compare it with LP in the presence of noise. The properties and applications of morphological filters for speech analysis are investigated. We introduce and investigate a novel nonlinear spectral envelope estimation method based on morphological operations, which is found to be very robust against noise. This method is also compared with the SEEVOC method. A simple method for the optimum selection of the structuring set size without using prior pitch information is proposed for many purposes. The morphological approach is then used for a new pitch estimation method and for the general sinusoidal analysis of speech or audio. Many of the new methods are based on a novel systematic analysis of the peak features of signals, including the study of higher order peaks. We propose a novel peak feature algorithm, which measure the peak characteristics of speech signal in time domain, to be used for end point detection and segmentation of speech. This nonparametric algorithm is flexible, efficient and very robust in noise. Several simple voicing measures are proposed and used in a new speech classifier. The harmonic-plus-noise decomposition technique is improved and extended to give an alternative to the methods used in the sinusoidal analysis method. Its applications to pitch estimation, speech classification and noise reduction are investigated.

James L. Massey. / "April 5, 1963." Issued also as a thesis, M.I.T. Dept. of Electrical Engineering, August 20, 1962. / Bibliography: p. 122-123. / Army Signal Corps Contract DA36-039-sc-78108. Dept. of the Army Task 3-99-25-001-08.

John W. Wozencraft and Michael Horstein. / "January 3, 1961." "Presented at the fourth London Symposium on Information Theory ... 1960." / Bibliography: p. 16. / Army Signal Corps Contract DA36-039-sc-78108. Dept. of the Army Task 3-99-20-001 and Project 3-99-00-000.

Marvin A. Epstein. / Based on a thesis submitted to the Dept. of Electrical Engineering, M.I.T., September 1958. "November 18, 1959." / Bibliography: p. 20. / Army Signal Corps Contract DA36-039-sc-78108. Dept. of the Army Task 3-99-20-001 and Project 3-99-00-000.

Peter Elias. / "September 20, 1957." "Reprinted from the 1957 IRE Wescon convention record, part 2." / Bibliography: p. 103. / U.S. Army Signal Corps Contract No. DA36-039-sc-64637 Dept. of the Army Task 3-99-06-108 Project 3-99-00-100

J.A. Roskind, P.A. Humblet. / "September 1981" Originally published as thesis (M.S., Dept. of Electrical Engineering and Computer Science, 1980). / "Grant NSF-ECS 79-19880"