The topic of this thesis is signaling design for data transmission through wireless channels between a transmitter and a receiver that can both be equipped with one or more antennas. In particular, the focus is on channels where the propagation coefficients between each transmitter--receiver antenna pair are only partially known or completetly unknown to the receiver and unknown to the transmitter. A standard signal design approach for this scenario is based on separate training for the acquisition of channel knowledge at the receiver and subsequent error-control coding for data detection over channels that are known or at least approximately known at the receiver. If the number of parameters to estimate in the acquisition phase is high as, e.g., in a frequency-selective multiple-input multiple-output channel, the required amount of training symbols can be substantial. It is therefore of interest to study signaling schemes that minimize the overhead of training or avoid a training sequence altogether. Several approaches for the design of such schemes are considered in this thesis. Two different design methods are investigated based on a signal representation in the time domain. In the first approach, the symbol alphabet is preselected, the design problem is formulated as an integer optimization problem and solutions are found using simulated annealing. The second design method is targeted towards general complex-valued signaling and applies a constrained gradient-search algorithm. Both approaches result in signaling schemes with excellent detection performance, albeit at the cost of significant complexity requirements. A third approach is based on a signal representation in the frequency domain. A low-complexity signaling scheme performing differential space--frequency modulation and detection is described, analyzed in detail and evaluated by simulation examples. The mentioned design approaches assumed that the receiver has no knowledge about the value of the channel coefficients. However, we also investigate a scenario where the receiver has access to an estimate of the channel coefficients with known error statistics. In the case of a frequency-flat fading channel, a design criterion allowing for a smooth transition between the corresponding criteria for known and unknown channel is derived and used to design signaling schemes matched to the quality of the channel estimate. In particular, a constellation design is proposed that offers a high level of flexibility to accomodate various levels of channel knowledge at the receiver. / QC 20101014

This thesis investigates channel-coded physical layer network coding, in which the relay directly transforms the noisy superimposed channel-coded packets received from the two end nodes, to the network-coded combination of the source packets. This is in contrast to the traditional multiple-access problem, in which the goal is to obtain each message explicitly at the relay. Here, the end nodes $A$ and $B$ choose their symbols, $S_A$ and $S_B$, from a small non-binary field, $\mathbb{F}$, and use non-binary PSK constellation mapper during the transmission phase. The relay then directly decodes the network-coded combination ${aS_A+bS_B}$ over $\mathbb{F}$ from the noisy superimposed channel-coded packets received from two end nodes. Trying to obtain $S_A$ and $S_B$ explicitly at the relay is overly ambitious when the relay only needs $aS_B+bS_B$. For the binary case, the only possible network-coded combination, ${S_A+S_B}$ over the binary field, does not offer the best performance in several channel conditions. The advantage of working over non-binary fields is that it offers the opportunity to decode according to multiple decoding coefficients $(a,b)$. As only one of the network-coded combinations needs to be successfully decoded, a key advantage is then a reduction in error probability by attempting to decode against all choices of decoding coefficients. In this thesis, we compare different constellation mappers and prove that not all of them have distinct performance in terms of frame error rate. Moreover, we derive a lower bound on the frame error rate performance of decoding the network-coded combinations at the relay. Simulation results show that if we adopt concatenated Reed-Solomon and convolutional coding or low density parity check codes at the two end nodes, our non-binary constellations can outperform the binary case significantly in the sense of minimizing the frame error rate and, in particular, the ternary constellation has the best frame error rate performance among all considered cases.

Purpose: The aim of this thesis is to explore the impact that increased availability of digital distribution has on physical distribution. The focus is on the effects that digital distribution has on the value creating processes of game developers with regard to distribution alternatives, strategic networks and consumer interaction. Additionally we examine if there is a future for physical distribution of games in an increasingly digital market. Background: It is estimated that only the online gaming market alone will turn over more than $13 billion in 2013. In terms of market potential this means that video gaming has already surpassed the movie industry and is closing in on the music industry (Jöckel, Will & Schwarzer, 2008). Digital distribution is gaining ground in the game industry (Cook, 2012), and access to high-speed internet connectivity is also increasing at a rapid pace. This creates a choice for game developers to adapt their strategies to the new ways of distribution. The previous view of the market was a linear value chain where developers must use intermediaries to reach an end consumer (Williams, 2002). The network dynamics appear to have changed, consumers have an impact on development and there are more complex interactions between the actors in order to generate better value. Method: The thesis uses an exploratory qualitative research method by conducting semi-structured interviews with developers on how the distribution channels have changed. Secondary data concerning the value chain, networks, and value constellations and was gathered to support the empirical background of the market. Conclusion: The value chain has been reconfigured from the classical value chain to a value constellation as increased online availability has changed the distribution possibilities allowing reciprocal relationships and user co-production as well as disintermedation of middle-hands. Value is created for the game developers through three different paths in our own value constellation: portals, direct sales homepage, and through publisher. In all three paths consumers play an important role through user participation in the value creation through user created content and user feedback through community and fan-base activities.. Our conclusion is that the future of physical distribution in the current format is threatened by digital alternatives, and will likely be discontinued in the long run and/or radically changed to include more physical value adding content.

<p>The topic of this thesis is signaling design for data transmission through wireless channels between a transmitter and a receiver that can both be equipped with one or more antennas. In particular, the focus is on channels where the propagation coefficients between each transmitter--receiver antenna pair are only partially known or completetly unknown to the receiver and unknown to the transmitter.</p><p>A standard signal design approach for this scenario is based on separate training for the acquisition of channel knowledge at the receiver and subsequent error-control coding for data detection over channels that are known or at least approximately known at the receiver. If the number of parameters to estimate in the acquisition phase is high as, e.g., in a frequency-selective multiple-input multiple-output channel, the required amount of training symbols can be substantial. It is therefore of interest to study signaling schemes that minimize the overhead of training or avoid a training sequence altogether.</p><p>Several approaches for the design of such schemes are considered in this thesis. Two different design methods are investigated based on a signal representation in the time domain. In the first approach, the symbol alphabet is preselected, the design problem is formulated as an integer optimization problem and solutions are found using simulated annealing. The second design method is targeted towards general complex-valued signaling and applies a constrained gradient-search algorithm. Both approaches result in signaling schemes with excellent detection performance, albeit at the cost of significant complexity requirements.</p><p>A third approach is based on a signal representation in the frequency domain. A low-complexity signaling scheme performing differential space--frequency modulation and detection is described, analyzed in detail and evaluated by simulation examples.</p><p>The mentioned design approaches assumed that the receiver has no knowledge about the value of the channel coefficients. However, we also investigate a scenario where the receiver has access to an estimate of the channel coefficients with known error statistics. In the case of a frequency-flat fading channel, a design criterion allowing for a smooth transition between the corresponding criteria for known and unknown channel is derived and used to design signaling schemes matched to the quality of the channel estimate. In particular, a constellation design is proposed that offers a high level of flexibility to accomodate various levels of channel knowledge at the receiver.</p>

Le contexte de cette thèse est la reconnaissance de systèmes de communication dans un contexte non coopératif. Nous nous intéressons au problème de la reconstruction de codes convolutifs et à la reconstruction du mapping (la bijection utilisée pour associer une séquence binaire à un signal modulé). Nous avons élaboré une nouvelle méthode statistique qui à partir d'une séquence binaire bruitée observée permet de détecter si une séquence binaire est codée par un codeur convolutif. Cette méthode consiste à former des blocs de séquence suffisamment grands pour contenir le support d'une équation de parité et à compter le nombre de blocs identiques. Elle a l'avantage de fournir la longueur du code utilisé lorsque le mapping est inconnu. Cette méthode peut également être utilisée pour reconstruire le dual d'un code convolutif lorsque le mapping est connu. Nous proposons par ailleurs un algorithme de reconnaissance de mapping basé sur le parcours de classes d'équivalences. Deux types de classes sont définies. Nous disposons d'un signal bruité partiellement démodulé (démodulé avec un mapping par défaut) et supposons que les données sont codées par un codeur convolutif. Nous utilisons la reconnaissance d'un tel code comme testeur et parcourons enfin les classes d'équivalences faisant apparaître une structure de codes convolutifs. Cette classification améliore la complexité de la recherche pour les petites constellations (4 et 8-PSK). Dans le cas des constellations 16 à 256-QAM l'algorithme est appliqué aux mappings Gray ou quasi-Gray. L'algorithme ne fournit pas un résultat unique mais il permet de trouver un ensemble de mappings possibles à partir de données bruitées.

This thesis investigates channel-coded physical layer network coding, in which the relay directly transforms the noisy superimposed channel-coded packets received from the two end nodes, to the network-coded combination of the source packets. This is in contrast to the traditional multiple-access problem, in which the goal is to obtain each message explicitly at the relay. Here, the end nodes $A$ and $B$ choose their symbols, $S_A$ and $S_B$, from a small non-binary field, $\mathbb{F}$, and use non-binary PSK constellation mapper during the transmission phase. The relay then directly decodes the network-coded combination ${aS_A+bS_B}$ over $\mathbb{F}$ from the noisy superimposed channel-coded packets received from two end nodes. Trying to obtain $S_A$ and $S_B$ explicitly at the relay is overly ambitious when the relay only needs $aS_B+bS_B$. For the binary case, the only possible network-coded combination, ${S_A+S_B}$ over the binary field, does not offer the best performance in several channel conditions. The advantage of working over non-binary fields is that it offers the opportunity to decode according to multiple decoding coefficients $(a,b)$. As only one of the network-coded combinations needs to be successfully decoded, a key advantage is then a reduction in error probability by attempting to decode against all choices of decoding coefficients. In this thesis, we compare different constellation mappers and prove that not all of them have distinct performance in terms of frame error rate. Moreover, we derive a lower bound on the frame error rate performance of decoding the network-coded combinations at the relay. Simulation results show that if we adopt concatenated Reed-Solomon and convolutional coding or low density parity check codes at the two end nodes, our non-binary constellations can outperform the binary case significantly in the sense of minimizing the frame error rate and, in particular, the ternary constellation has the best frame error rate performance among all considered cases.

[pt] As atuais pesquisas em Ergonomia do Ambiente Construído investigam os usuários e sua relação com o ambiente através de métodos específicos com foco na Ergonomia física e na percepção do usuário. Pretende-se nessa pesquisa analisar o Método Constelação de Atributos orientada para a percepção do usuário e a partir desta, propor um novo método. O estudo do método, bem como sua aplicação será exemplificado através de pesquisa realizada utilizando as cozinhas residenciais como aplicação prática da pesquisa. A cozinha é um dos ambientes que mais tem sofrido sensíveis mudanças nos aspectos sociais, econômicos, tecnológicos, ergonômicos, entre outros. Faz-se um resgate histórico desde espaço desde a Idade Média até as atuais cozinhas utilizadas pela sociedade brasileira. Realiza-se uma busca pelas legislações e normas técnicas que definem os espaços de cozinhas em apartamentos multifamiliares, através dos Códigos de Obra e Edificações de seis capitais brasileiras e avalia-se a Norma NBR 14033 que trata de mobiliário de cozinhas residenciais. Durante a realização desta pesquisa avaliou-se o Método Constelação de Atributos sua aplicação e resultados em uma pesquisa aplicada e ainda, em outras duas dissertações de mestrado onde o método também foi utilizado. A partir de análises realizadas propõe-se uma nova metodologia como forma de aprimorar e qualificar os atributos atribuídos a um ambiente construído por parte de especialistas e usuários, fundamentado na metodologia já existente. A nova metodologia é aplicada a um grupo de especialistas e usuários na cidade do Rio de Janeiro. Conclui-se o trabalho com a definição detalhada de uma nova metodologia de investigação da percepção do usuário frente ao ambiente construído. / [en] The current research in the Built Environment Ergonomics investigate users and their relation ship to the environment through specific methods with focus on ergonomics physical and perception of the user. It is intended that research examine the existing methodologies for user perception and propose a new method. The target system used in this study are the home kitchens, this environment has been more sensitive to changes in social, economic, technological, ergonomic, and others. It is a historical review from space since the Middle Ages to today s kitchens used by Brazilian society. Held a search for the laws and technical standards that define the spaces of kitchens in apartments multifamily, through the Building Codes Work and in six Brazilian cities and assesses the technical standard NBR 14033 of furniture that comes from home kitchens. During this research evaluated the Constellation Method Attributes its application and results in experimental research and two dissertations where the method was also applied. From the analysis carried out and some pre-tests performed developed a new methodology as a way to enhance and qualify the attributes assigned to an environment built by experts and users. So, we propose a new method based on existing methodology. The new methodology is applied to a group of experts and users in Rio de Janeiro. It is working with the detailed definition of a new methodology for the investigation of perception of the user facing the built environment.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-04-20T22:42:49Z No. of bitstreams: 1 RAPHAEL TAVARES DE ALENCAR - DISSERTAÇÃO PPGEE 2014..pdf: 1279047 bytes, checksum: 21e02690d9f7fa6020cc8bc9de97b124 (MD5) / Made available in DSpace on 2018-04-20T22:42:49Z (GMT). No. of bitstreams: 1 RAPHAEL TAVARES DE ALENCAR - DISSERTAÇÃO PPGEE 2014..pdf: 1279047 bytes, checksum: 21e02690d9f7fa6020cc8bc9de97b124 (MD5) Previous issue date: 2014-08 / O canal sem fio tem características de desvanecimento devido ao multipercurso, visto que há reflexões e espalhamentos ao longo do caminho percorrido pelo sinal. O desvanecimento é considerado uma das principais causas de degradação do desempenho em um sistema de comunicações móveis, visto que depende fortemente do canal em que se propaga o sinal transmitido. A diversidade de modulação é uma técnica eficiente em termos de utilização de banda de frequência, que consiste na rotação da constelação do sinal digital transmitido associado ao entrelaçamento das componentes de modulação em fase e em quadratura da constelação do sinal. O objetivo da diversidade em modulação é mitigar os efeitos do desvanecimento em comunicações sem fio. Esta dissertação aborda o estudo da diversidade de modulação no cenário de múltiplos raios de propagação Osresultadosapresentamsimulaçõesdecenárioscom múltiplos raios, isto é, o sinal é transmitido por múltiplos percursos, cada um associado a um fator de desvanecimento e um atraso aleatórios. São feitas comparações entre as taxas de erros para oito cenários com e sem interferência intersimbólica, de um a seis raios, com e sem linha de visada, para os esquemas de modulação digital 4-PSK e 8-PSK. São apresentadas as comparações entre os resultados de taxas de erros com e sem o uso da técnica de diversidade de modulação, com a intenção de avaliar o ganho desta técnica nestes cenários. Também é feita uma análise para obter o ângulo de rotação ótimo para as constelações mencionadas, considerando diferentes cenários de multipercurso. Para tanto, são empregados os conceitos de esquemas de modulação digital, múltiplos percursos, distribuições de probabilidade, canais de comunicação e técnicas de diversidade. / The wireless channel has characteristics of multipath fading,due to reflections and scattering that the signal suffers over the propagation path. Fading is considered one of the main causes of performance degradation of a mobile communications system, as it strongly depends on the channel through which the signal is transmitted. Modulation diversity is a bandwidth-efficient technique that consist on the rotation of the digital signal constellation. assiciated with the interleaving of the in-phase and quadrature modulation components. The objective of the modulation diversity technique is to mitigate the effects of fading in wireless communications The results present simulations of multipath scenarios, that is, the signal is transmitted through multiple channels, each one associated with a stochastic fading factor and random delay Biterrorratesareevaluatedandcomparedforforeightdifferentscenarioswithandwithout intersymbolicinterference,fromonetosixpaths,withandwithoutlineofsight,for4-PSKand 8-PSKdigitalmodulationschemes. Transmissionbiterrorratevalues,withandwithouttheuse ofmodulationdiversityarecompared,astoevaluatethegainofthisdiversitytechniqueforsuch scenarios. Also, an analysis is performed to obtain the optimum rotation angle for the mentioned constellations, considering the different multipath scenarios. In this regard, concepts of digital modulation schemes, multiple paths, probability distributions, communication channels and diversity techniques are used.

Made available in DSpace on 2014-12-17T14:55:42Z (GMT). No. of bitstreams: 1 TallesRF_DISSERT.pdf: 1140964 bytes, checksum: 341e86481dc2ae47c2cea90b012c9fc6 (MD5) Previous issue date: 2009-03-12 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Wavelet coding is an efficient technique to overcome the multipath fading effects, which are characterized by fluctuations in the intensity of the transmitted signals over wireless channels. Since the wavelet symbols are non-equiprobable, modulation schemes play a significant role in the overall performance of wavelet systems. Thus the development of an efficient design method is crucial to obtain modulation schemes suitable for wavelet systems, principally when these systems employ wavelet encoding matrixes of great dimensions. In this work, it is proposed a design methodology to obtain sub-optimum modulation schemes for wavelet systems over Rayleigh fading channels. In this context, novels signal constellations and quantization schemes are obtained via genetic algorithm and mathematical tools. Numerical results obtained from simulations show that the wavelet-coded systems derived here have very good performance characteristics over fading channels / A codifica??o por matrizes wavelets tem se mostrado um m?todo eficiente para combater o desvanecimento, fen?meno que causa flutua??es na intensidade do sinal transmitido em um canal de comunica??o sem fio, devido ? propaga??o por m?ltiplos percursos. Mas como os s?mbolos codificados pelo sistema wavelet s?o n?o-equiprov?veis, os esquemas de modula??o influenciam de maneira fundamental o desempenho desse sistema. Por isso se torna essencial um m?todo eficaz para a obten??o desses esquemas de modula??o de forma a otimizar o desempenho do sistema wavelet, principalmente quando se emprega matrizes wavelets de grandes dimens?es. Esse trabalho aborda o projeto de esquemas de modula??o para um sistema de transmiss?o sem fio baseado na codifica??o por matrizes wavelets em canais com desvanecimento Rayleigh plano. Para o projeto desses esquemas de modula??o s?o criados novas constela??es e esquemas de quantiza??o. O projeto desses esquemas de modula??o ? guiado por um algoritmo gen?tico. Os resultados obtidos atrav?s de simula??es computacionais mostram que os sistemas wavelets empregando esses esquemas obtiveram um bom desempenho em canais caracterizados pelo desvanecimento Rayleigh

Orientador: Reginaldo Palazzo Junior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-11T09:02:46Z (GMT). No. of bitstreams: 1 Cavalcante_RodrigoGusmao_D.pdf: 1972914 bytes, checksum: 6cdc127efe5cbfcb242fe471138f03f4 (MD5) Previous issue date: 2007 / Resumo: Em geral, o espaço EucIidiano é utilizado no projeto e na análise de desempenho da maior parte dos sistemas de comunicações atuais. Nesta tese, verificamos que o modelo de um sistema de comunicação não necessariamente está restrito ao espaço Euclidiano, mas sim a uma variedade Riemanniana. Com isso, os sistemas de comunicaçoes podun ser analisados em um contexto mais geral, no qual constatamos que a curvatura do espaço influencia em seus desempenhos. Corno exemplo, estudamos a curvatura de meios ópticos e propomos novos perfis de guias de ondas, fibras ópticas e lentes de interesse prático. Além disso, caracterizamos a curvatura de modulações não-lineares (twisted) e verificamos que o valor máximo permitido para a energia média do ruído está relacionada ao valor da curvatura da modulação. Neste contexto, as moclulações associadas a superfícies mínimas apresentaram bons desempenhos, pois tais modulações são pontos críticos do erro quadrático médio. Mostramos também que o espaço de sinais possui métrica induzida da superfície associada à modulação. Com isso, foi possível demonstrar que os espaços de sinais com curvatura negativa são os que apresentam melhor desempenho segundo a probabilidade média de erro. Dessa forma, alguns exemplos de constelações de sinais geometricamente uniformes foram construídos e analisados em variedades Riemannianas. Finalizamos este trabalho notando que na maioria das vezes que o espaço hiperbólico é utilizado nos blocos ele um sistema ele comunicações, o desempenho desse sistema tende a se aproximar do ponto ótimo de operação / Abstract: ln general, the Euclidian space is used in the design and performance analysis in most of the current communication systems. ln this thesis, we note that the model of a communication system is not necessarily restricted to the Euclidian space, more precisely, the model can be linked to Riemannian manifolds. Thus, the communication systems could be analyed in a broader context, in which the curvature of space influence on their performance. As an example, we studied the curvature of optical medium and propose new profiles of waveguides, optical fibers and lenses of practical interest. Moreover, we have characterized the curvature of twisted modulations and found that the maximum value allowed for the average energy of noise is related to the value of the curvature of the modulation. ln this context, the modulation associatecl with minimal surfaces showed good performance, because these modulations are critical points of minimum the mean-square error. VVe show that the signal space has induced metric associated with surface of the modulation. Thus, we have shown that the signal space with negative curvature is the space where the average error probability decrease a function of the curvature. Thus, some examples of geometrically uniform signal constellations were constructecl and analyzed on Riemannian manifolds. Finally we note that most of the time that hyperbolic space is considered in blocks of a communication system, then the performance of this system tends to be closer to the optimum point of operation / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica