Single-carrier linear modulation techniques combined with frequency-domain equalization provide a viable alternative to multicarrier techniques for combating multipath fading in channels with large delay spread. Such modulations tolerate frequency offset and have well controlled peak to average power ratio. They have comparable complexity to orthogonal frequency division multiplexing (OFDM) systems, and are more robust to synchronization errors. If error correction coding is used, then information can be iteratively passed between the equalizer and the decoder to improve performance. This is referred to as turbo equalization. To date, several turbo equalization schemes have been proposed, but little work has been done to address the problem of channel estimation for the turbo equalization process. The work in this thesis considers frequency-domain turbo equalization with imperfect channel state information (CSI) at the receiver for different wireless channels. A receiver structure incorporating joint frequency-domain turbo equalization and time- domain channel estimation is developed. The novelty of this scheme lies in the combination of time-domain channel estimation and frequency-domain turbo equalization, and in its extension to high level modulation formats. The performance of the system is investigated by a combination of analysis and computer simulation. It is found that the system performs well over a range of dispersive channels.

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Consider the problem of designing capacity-achieving codes for multi-terminal communication scenarios. For point-to-point communication problems, one can optimize a single code to approach capacity, but for multi-terminal problems this translates to optimizing a single code to perform well over the entire region of channel parameters. A coding scheme is called universal if it allows reliable communication over the entire achievable region promised by information theory. It was recently shown that terminated low-density parity-check convolutional codes (also known as spatially-coupled low-density parity-check ensembles) have belief-propagation thresholds that approach their maximum a-posteriori thresholds. This phenomenon, called "threshold saturation via spatial-coupling," was proven for binary erasure channels and then for binary memoryless symmetric channels. This approach provides us with a new paradigm for constructing capacity approaching codes. It was also conjectured that the principle of spatial coupling is very general and that the phenomenon of threshold saturation applies to a very broad class of graphical models. In this work, we consider a noisy Slepian-Wolf problem (with erasure and binary symmetric channel correlation models) and the binary-input Gaussian multiple access channel, which deal with correlation between sources and interference at the receiver respectively. We derive an area theorem for the joint decoder and empirically show that threshold saturation occurs for these multi-user scenarios. We also show that the outer bound derived using the area theorem is tight for the erasure Slepian-Wolf problem and that this bound is universal for regular LDPC codes with large left degrees. As a result, we demonstrate near-universal performance for these problems using spatially-coupled coding systems.

[pt] Este trabalho analisa algumas estratégias para decodificação de sinais TCM. Além disto, propõe-se uma nova estratégia que faz uso de um processamento por percurso sobrevivente na treliça de decodificação para gerar e atualizar, de acordo com um algoritmo do tipo PLL, um conjunto de estimativas de fase, cada uma associada a um estado da treliça, que são utilizadas simultaneamente no processo de decodificação. Expressões úteis para o direcionamento de parâmetros usados no algoritmo de estimação são apresentadas. Estas expressões foram baseadas em uma análise linear simplificada que considerou tanto o desempenho do estimador em estado estacionário quanto no período transiente. Resultados de desempenho obtidos, via simulação, com o uso do método proposto são comparados com resultados obtidos com outras estratégias para recuperação de portadora em sistemas TCM. Estes resultados mostram uma clara superioridade do método proposto para diversos tipos de erros de fase. / [en] This thesis analyses some coherent decoding schemes for TCM signals reception. In addition, a new scheme, which makes use of a per survivor processing, is propoed. In this scheme, each trellis state has an associated phase estimate which is generated by a data-aided PLL-like algorithm, based on the survivor sequence associated to that state. Some useful expressions are developed to help the parameters selection for use on the estimation algorthm. These expressions are based on a simplified linear analysis which are carried out on both transient and stationary cases. We compare the proposed scheme performance to others schemes by means of computer simulation. These results show that the new scheme has better performance in terms of bit-error-rate.

A forward error correction technique known as convolutional coding with Viterbi decoding was explored in this final thesis. This Viterbi project is part of the baseband Error control project at electrical engineering department, Linköping University. In this project, the basic Viterbi decoder behavior model was built and simulated. The convolutional encoder, puncturing, 3 bit soft decision, BPSK and AWGN channel were implemented in MATLAB code. The BER was tested to evaluate the decoding performance. The main issue of this thesis is to implement the RTL level model of Viterbi decoder. With the testing results of behavior model, with minimizing the data path, register size and butterflies in the design, we try to achieve a low silicon cost design. The RTL Viterbi decoder model includes the Branch Metric block, the Add-Compare-Select block, the trace-back block, the decoding block and next state block. With all done, we further understand about the Viterbi decoding algorithm and the DSP implementation methods.

The relationship between children's emotion decoding ability and their social acceptance was examined, with a major focus on potential nonlinear components. Based on the display rules literature, the prediction was tested that social acceptance and emotion decoding skills can be best described as an inverted U-shaped function. Children in kindergarten through fifth grade (113 girls and 123 boys) completed measures of postural and facial decoding accuracy (FACES and TALK) and their social acceptance was assessed using child and teacher reports (SPPC or PSPC). The results showed only a statistically significant quadratic relationship for girls and a statistically significant linear relationship for boys in the link between postural decoding and teacher-rated social acceptance.

Most research investigating vocal expressions of emotion has focused on one or more of three questions: whether there exist unique acoustic profiles of individual encoded emotions, whether the nature of emotion expression is universal across cultures, and how accurately decoders can identify expressed emotions. This dissertation begins to answer a fourth question, whether there exist unique patterns in the types of acoustic properties persons focus on to identify vocalized emotions. Three hypotheses were tested: first, whether acoustic patterns are interpreted idiographically or nomothetically as reflected in a comparison of individual vs. group lens model identification ratios; second, whether there exists a decoder by emotion interaction for scores of accuracy; and third, whether such an interaction is mediated by the acoustic properties of the vocalized emotions. Results from hypothesis one indicate there is no difference between individual and group identification ratios, demonstrating that vocalized emotions are decoded nomothetically. Results from hypothesis two indicate there is not a significant decoder by emotion interaction on scores of accuracy, demonstrating that decoders who are generally good (or bad) at identifying some vocalized emotions tend to be generally good (or bad) at identifying all vocalized emotions. There are, however, significant main effects for both emotion and decoder. Anger and happiness are more accurately decoded than fear and sadness. Perhaps most importantly, multivariate results from hypothesis three indicate strong and consistent differences across the four emotions in the way they are identified acoustically. Specifically, decoders identify anger by primarily focusing on spectral characteristics, fear by primarily focusing on frequency (F0), happiness by primarily focusing on rate, and sadness by focusing on both intensity and rate. These acoustic mediation differences across the emotions are also shown to be nomothetic, that is, they are surprisingly consistent across decoders.

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