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This dissertation proposes an iterative confidence passing (ICP) approach for parameter estimation. The dissertation describes three different algorithms that follow from this ICP approach. These three variations of the ICP approach are applied to (a) macrodiversity and user cooperation diversity reception problems, (b) the co-operative multipoint MIMO reception problem (pertinent to the LTE Advanced system scenarios), and (c) the satellite beamforming problem. The first two of these three applications are some of the significant open DSP research problems that are currently being actively pursued in academia and industry. This dissertation demonstrates a significant performance improvement that the proposed ICP approach delivers compared to the existing known techniques. The proposed ICP approach jointly estimates (and, thereby, separates) two sets of unknown parameters from the receiver measurements. For applications (a) and (b) mentioned above, one set of unknowns is comprised of the discrete-valued information-bearing transmitted symbols in a multi-channel communication system, and the other set of unknown parameters is formed by the coefficients of a Rayleigh or Rician fading channel. Application (a) is for interference-free, cooperative or macro, transmit or receive, diversity scenarios. Application (b) is for MIMO systems with interference-rich reception. Finally, application (c) is for an interference-free spacecraft array calibration system model in which both the sets of unknowns are complex continuous valued variables whose magnitude follows the Rician distribution. The algorithm described here is the outcome of an investigation for solving a difficult channel estimation problem. The difficulty of the estimation problem arises because (i) the channel of interest is intermittently observed, and (ii) the partially observed information is not directly of the channel of interest; it has dependency on another unknown and uncorrelated set of complex-valued random variables. The proposed ICP algorithmic approach for solving the above estimation problems is based on an iterative application of the Weighted Least Squares (WLS) method. The main novelty of the proposed algorithm is a back and forth exchange of the confidence or the belief values in the WLS estimates of the unknown parameters during the algorithm iterations. The confidence values of the previously obtained estimates are used to derive the estimation weights at the next iteration, which generates an improved estimate with a greater confidence. This method of iterative confidence (or belief) passing causes a bootstrapping convergence to the parameter estimates. Besides the ICP approach, several alternatives are considered to solve the above problems (a, b and c). Results of the performance simulation of the alternative methods show that the ICP algorithm outperforms all the other candidate approaches. Performance benefit is significant when the measurements (and the initial seed estimates) have non-uniform quality, e.g., when many of the measurements are either non-usable (e.g., due to shadowing or blockage) or are missing (e.g., due to instrument failures). / Ph. D.

The inadequacy of conventional CDMA receivers in a multiple access interference-limited mobile radio environment has spurred research on advanced receiver technologies. This research investigates the use of adaptive receivers for single user demodulation to overcome some of the deficiencies of a conventional receiver and, hence, enhance the system capacity. Several new adaptive techniques are proposed. The new techniques and some existing schemes are analyzed. The limitation of existing blind algorithms in multipath channels is analyzed and a new blind algorithm is proposed that overcomes this limitation. The optimal receiver structure for multi-rate spread spectrum systems is derived and the performance of this receiver in various propagation channels is investigated. The application of coherent and differentially coherent implementations of the adaptive receiver in the presence of carrier frequency offsets is analyzed. The performance of several new adaptive receiver structures for frequency offset compensation is also studied in this research. Analysis of the minimum mean-squared error receiver is carried out to provide a better understanding of the dependence of its performance on channel parameters and to explain the near-far resilience of the receiver. Complex differentially coherent versions of the sign algorithm and the signed regressor algorithm, algorithms that have a much lower computational complexity than the least-means square algorithm, are proposed and applied for CDMA interference rejection. / Ph. D.

Cette thèse a permis de travailler sur l'efficacité d'un canal des systèmes massifs MIMO pour lesquels il faille déterminer le débit à l'Uplink des terminaux présents dans leurs cellules respectives. Comme hypothèse, la bande de fréquence en mode TDD est réutilisée dans chaque cellule. Tous les symboles sont propagés de manière asynchrone par les terminaux présents dans les cellules, n'empêchant pas de fait des interactions intra et inter symboles au niveau des stations de base. Ces signaux rencontrent beaucoup d'obstacles sur leur trajet qui entraînent des retards, des pertes de signaux (destructifs), des régénérations de signaux (constructifs) avec divers types de modulation (amplitude, fréquentielle, phase), etc. L’affaiblissement du trajet dans le canal est mis en exergue avec les différentes valeurs prises par le coefficient d'atténuation choisi lors des simulations. Face à cette situation, il a fallu rechercher le meilleur et robuste estimateur de canal à un temps de cohérence donné. La méthode MMSE (Minimum Mean Square Error) est retenue, comparée à d'autres. Pour la performance des systèmes massifs MIMO, nous nous sommes appesantis sur les méthodes de diversité des antennes (diversité d'ordre N), les méthodes de coding, les méthodes d'accès OFDMA et les méthodes d'égalisation pour montrer qu'effectivement le fait d'utiliser de nombreuses antennes au niveau des stations de base améliore et contribue aux gains recherchés en débits. Avec les systèmes massifs MIMO, nous avons montré que l'apport antennaire est bien reconnu dans la gestion des interférences. Un algorithme de calcul de débit à l'Uplink a été réalisé avec trois récepteurs conventionnels que sont le MRC (Maximum Ratio Combiner), le ZF (Zero-Forcing) et le MMSE (Minimum Mean Square Error). Les simulations ont permis de comparer les différentes approches. En faisant varier la puissance de contamination des symboles pilotes, nous observons la convergence des courbes ZF et MMSE. Si le nombre des cellules L augmentent, nous constatons que plus la puissance de contamination des symboles pilotes (pp) est élevée, plus la capacité diminue dans le canal. Après plusieurs itérations, notre algorithme converge vers une asymptote (régime stationnaire et linéaire) où les échantillons à la sortie des détecteurs s’approchent de la séquence de données émises. Le SINR obtenu avec les détecteurs conventionnels permet le calcul des débits respectifs dans le canal avec le théorème de SHANNON. / This thesis made it possible to work on the efficiency of a channel of massive MIMO systems for which it is necessary to determine the throughput at the Uplink of the terminals present in their respective cells. As an assumption, the frequency band in TDD mode is reused in each cell. All symbols are propagated asynchronously by the terminals present in the cells, not effectively preventing intra- and inter-symbol interactions at the base stations. These signals encounter many obstacles on their path that lead to delays, signal losses (destructive), signal regenerations (constructive) with various types of modulation (amplitude, frequency, phase), etc. The path loss in the channel is highlighted with the different values taken by the attenuation coefficient chosen during the simulations. Faced with this situation, it was necessary to look for the best and most robust channel estimator at a given consistency time. The MMSE (Minimum Mean Square Error) method is used, compared to others. For the performance of massive MIMO systems, we have focused on antenna diversity methods (N-order diversity), coding methods, OFDMA access methods and equalization methods to show that effectively using multiple antennas at base stations improves and contributes to the desired rate gains. With massive MIMO systems, we have shown that antennar contribution is well recognized in interference management. An algorithm for calculating the flow rate at the Uplink was developed using three conventional receivers: the MRC (Maximum Ratio Combiner), the ZF (Zero-Forcing) and the MMSE (Minimum Mean Square Error). The simulations made it possible to compare the different approaches. By varying the contamination power of the pilot symbols, we observe the convergence of the ZF and MMSE curves. If the number of L cells increases, we find that the higher the contamination power of the pilot symbols (pp), the lower the capacity in the channel. After several iterations, our algorithm converges to an asymptote (stationary and linear regime) where the samples at the detector output approach the transmitted data sequence. The SINR obtained with conventional detectors allows the calculation of the respective flows in the channel with the SHANNON theorem.

Introdução: O comprometimento cognitivo (CC) na Esclerose Múltipla (EM) possui taxas de prevalência de 43% a 70% e pode surgir desde a Síndrome Clinicamente Isolada (CIS) aos estágios iniciais da EM. O CC na EM pode evoluir independentemente dos sinais e sintomas motores, dos resultados do EDSS e ausência de lesões ativas (captantes) na Ressonância Magnética. Neste contexto, o Multiple Sclerosis National Questionaire (MSNQ) e o protocolo Brief International Cognitive Assesment for Multiple Sclerosis (BICAMS) são instrumentos internacionais empregados para a triagem e o monitoramento nos centros de atendimento para os pacientes com EM. Estudos posteriores e reuniões do mesmo comitê concluíram que o MSNQ possui várias limitações por ser uma medida não objetiva e a triagem única pelo Symbol Digit Modalities Test (SDMT) por si só não é capaz de acessar outras áreas que podem estar comprometidas na EM. Com a segunda revisão do MMSE, e na falta de instrumentos de triagem objetivos capazes de triar os pacientes que precisassem ser melhor acompanhados pelo BICAMS, buscou-se no presente estudo criar a partir do BICAMS e do MMSE-2 uma medida rápida para triagem, que tivesse medidas de memória episódica, velocidade de processamento, atenção e memória operacional. Objetivo: Para obter uma ferramenta de triagem para este propósito (MMSE-MS) foram conduzidos estudos de adaptação segundo o estímulo: estudo de protótipos, estudo de adaptação, propriedades psicométricas e normas do MMSE-2 (como a nossa ferramenta experimental) e estudo preliminar de desenvolvimento de uma ferramenta objetiva de triagem para EM, com base no MMSE-3. Métodos: Todos os estudos de tradução e adaptação foram conduzidos seguindo um mesmo método, já amplamente utilizado pela literatura. O primeiro estudo consistiu no estudo convencional e de protótipos para verificar qual possuía melhor estimativa de equivalência entre as culturas. O segundo estudo consistiu em adaptar, verificar as propriedades psicométricas e estabelecer normas para o MMSE-2. Similarmente ao estudo anterior, um juiz internacional discutiu os resultados do estudo de adaptação para estabelecimento dos parâmetros de transculturalidade. O último estudo foi realizado com o objetivo de obter uma ferramenta com estimativas de sensibilidade e especificidade similares ao BICAMS, mas que fosse designada à triagem dos pacientes que são elegíveis para ser acompanhados pelo BICAMS. Para tal participaram do primeiro estudo, 374 voluntários da comunidade e 25 pacientes com EM. No segundo e terceiro estudo, participaram 128 pacientes com EM e 602 voluntários saudáveis. Todos os estudos clínicos e com as amostras da comunidade foram realizados no período de 2013 à 2015 e contaram com a parceria em pesquisa do Instituto Brasileiro de Neuropsicologia (IBNeuro) e do Laboratório de Instrumentação e Avaliação Psicológica (LABIAP). A coleta de pacientes foi realizada no Ambulatório de Neuroimunologia do Hospital das clínicas da Faculdade de Medicina de Ribeirão Perto (FMRP-USP). Resultados: No primeiro estudo, foram mantidas 5 palavras das 15 da versão original. A razão para as modificações na lista Brasileira foram as diferenças entre a divisão silábica, extensão das palavras e presença de protótipos. Verificou-se ainda que até a quarta palavra evocada na nossa cultura em cada categoria semântica foram as mesmas que foram evocadas na língua nativa do instrumento, mas a ordem da frequência variou dentro de cada categoria, mostrando que embora existam palavras que são prototípicas às duas culturas na classificação semântica global, o contexto cultural interfere muito quando partimos para as especificidades dentro de cada classificação e categoria semântica. O MMSE-2 também apresentou estimativas de validade e precisão comum às duas culturas. No quarto estudo, as medidas do MMSE-2 que tiveram melhor relação com o BICAMS e índices de sensibilidade e especificidade parecidos foram as medidas da tarefa de evocação, atenção e cálculo, memória de histórias e codificação dígitos-símbolos. As correlações selecionadas foram aquelas classificadas em moderadas e fortes. Como segundo critério, as medidas do MMSE-2 foram comparadas às medidas do BICAMS pela curva ROC. As medidas do MMSE- 2 que tiveram especificidade e sensibilidade significativas (p<0,001) foram as elegíveis para compor o teste de triagem. Como a tarefa de codificação dígitos-símbolos é susceptível à demanda motora, optou-se pelo uso da forma oral do SDMT em conjunto. Deste modo, no nosso instrumento de triagem, normas para este instrumento foram criadas a partir da soma dos itens do MMSE-MS com o SDMT oral. Conclusão: A integração de dados desses diversos estudos evidencia cautela quanto aos procedimentos de adaptação empregados para adaptação transcultural das tarefas que são de origem verbal e semântica. Há também evidências da necessidade de instrumentos capazes de triar esses pacientes. Para tal, o MMSE-EM mostrou-se válido, preciso, com índices de sensibilidade e especificidade similares ao BICAMS, com normas ajustadas ao contexto Brasileiro. / Background: The cognitive impairment (CI) in Multiple Sclerosis (MS) has the prevalence rate from 43% to 70% and may occur from the Clinically Isolated Syndrome (CIS) to the early stages of MS. The CI in MS can advance independently of motor signs and symptoms, EDSS scores and MRI stable. In this context, the National Multiple Sclerosis Questionnaire (MSNQ) and the International Brief Cognitive Assesment for Multiple Sclerosis (BICAMS) are international tools used to screening and monitoring MS patients in care centers. Further studies and meetings provided by same committee alluded that MSNQ has several limitations for being a non-objective measure and the screening using the Symbol Digit Modalities Test (SDMT) alone is not effective because other areas that may be impaired in MS is not screened. With the second revision of the MMSE, and the lack of objective screening tools to quikly screening MS patients that needed to be monitored by BICAMS, we aimed in the presente study to create a fast measurement to screening the episodic memory, processing speed, attention and working memory from BICAMS and MMSE-2. Objective: To obtain brief a screening tool for MS (MMSE-MS) were conducted four studies using different tools: first the prototype study to development of CVLT-2 lists, adaptation, psychometric properties and normative data of BICAMS to the Braziliam context (as our gold standard), Cross cultural adaptation, psychometric properties, and normative data of MMSE-2 (the experimental tool) and the preliminary study of development of MMSE-MS. Methods: All translation and adaptation studies were conducted following the same method, as widely used in the literature. The first study consisted of conventional adaptation and prototypical norms, aiming to see which had the best estimates of equivalence between the cultures. The second study with BICAMS protocol show that MS scored significantly lower on all BICAMS tests. At the end of the study, the results were discussed with a member of the international committee to confirm the evidences of transculturality between the original and Brazilian versions. The third study consisted of Adapt, to investigate the psychometric properties and stablish normative data to the MMSE-2. Similarly to the previous study, an international judge discussed the results of the study of adaptation to identify the estimatives of transculturality. The fourth and last study was conducted in order to obtain a tool with sensitivity and similar specificity estimates BICAMS, but it was designed to screen patients who are eligible to be accompanied by BICAMS. Participated of the first study, 374 healthy volunteers and 25 patients with MS. In the second and third study participated 128 MS patients and 602 healthy volunteers. All clinical studies and community samples were carried out from 2013 to 2015 and had the partnership of the Brazilian Institute of Neuropsychology (IBNeuro) and the Laboratory of Instrumentation and Psychological Assessment (LABIAP). The collection of patients was performed at the Neuroimmunology Outpatient Clinic from Ribeirão Preto Medical School (FMRP-USP). Results: In the first study, were kept 5 words of 15 from the original American version. The reason for these changes in the Brazilian list were the differences between the syllabic division, extension of the words and the presence of prototypicall words. Was also found that until the fourth word evoked in our culture, in each semantic category were the same as those mentioned in the native language, but the order of the frequency varied within each category, indicating that although there are words that are prototypically commom between the two cultures in the overall semantic classification, the cultural context changes when we analyse the specifics prototipically words inside of each classification and semantic categories. To the second study, the BICAMS showed similar estimates of reliability and validity for current use as monitoring tool for MS in the Brazilian contexto, supporting the diagnostic validity of the Brazilian-Portuguese adaptation The normative data were satisfactory (p <0.001) in relation to the vocational status. The third study, with MMSE-2 also provided good estimates of validity and precision to the both cultures. To the fourth study, the MMSE-2 was compared to the BICAMS. The MMSE-2 tasks which had similar sensitivity and specificity to the BICAMS protocol was the recalling, attention and calculation, history memory and processing speed (Symbol Digit-coding). The selected tasks were those classified as moderate and Strong correlations. The second procedure consisted on comparisions among the MMSE-2 measurements and BICAMS using ROC curve. So, the MMSE-2 measures that had significant (p <0.001) specificity and sensitivity and similar area under the curve (ROC) were eligible to composse the screening tool. As the digit-symbol coding task is susceptible to motor demand, we decided to include the oral SDMT to the task. Thus, to get our screening tool, normative data for this instrument were created from the sum of the MMSE-MS items with oral SDMT. Conclusion: The overall of the data from these studies calls attention to the necessity of the caution to the adaptation procedures used in cross-cultural adaptation of the tasks that has verbal and semantic stimuli. There is also the need of tools abel to screening MS patients. For this, these preliminar data for MMSE-MS showed evidences of validation, similar sensitivity and and specificity, with normative data culturally adjusted to the Brazilian context.

Introdução: O comprometimento cognitivo (CC) na Esclerose Múltipla (EM) possui taxas de prevalência de 43% a 70% e pode surgir desde a Síndrome Clinicamente Isolada (CIS) aos estágios iniciais da EM. O CC na EM pode evoluir independentemente dos sinais e sintomas motores, dos resultados do EDSS e ausência de lesões ativas (captantes) na Ressonância Magnética. Neste contexto, o Multiple Sclerosis National Questionaire (MSNQ) e o protocolo Brief International Cognitive Assesment for Multiple Sclerosis (BICAMS) são instrumentos internacionais empregados para a triagem e o monitoramento nos centros de atendimento para os pacientes com EM. Estudos posteriores e reuniões do mesmo comitê concluíram que o MSNQ possui várias limitações por ser uma medida não objetiva e a triagem única pelo Symbol Digit Modalities Test (SDMT) por si só não é capaz de acessar outras áreas que podem estar comprometidas na EM. Com a segunda revisão do MMSE, e na falta de instrumentos de triagem objetivos capazes de triar os pacientes que precisassem ser melhor acompanhados pelo BICAMS, buscou-se no presente estudo criar a partir do BICAMS e do MMSE-2 uma medida rápida para triagem, que tivesse medidas de memória episódica, velocidade de processamento, atenção e memória operacional. Objetivo: Para obter uma ferramenta de triagem para este propósito (MMSE-MS) foram conduzidos estudos de adaptação segundo o estímulo: estudo de protótipos, estudo de adaptação, propriedades psicométricas e normas do MMSE-2 (como a nossa ferramenta experimental) e estudo preliminar de desenvolvimento de uma ferramenta objetiva de triagem para EM, com base no MMSE-3. Métodos: Todos os estudos de tradução e adaptação foram conduzidos seguindo um mesmo método, já amplamente utilizado pela literatura. O primeiro estudo consistiu no estudo convencional e de protótipos para verificar qual possuía melhor estimativa de equivalência entre as culturas. O segundo estudo consistiu em adaptar, verificar as propriedades psicométricas e estabelecer normas para o MMSE-2. Similarmente ao estudo anterior, um juiz internacional discutiu os resultados do estudo de adaptação para estabelecimento dos parâmetros de transculturalidade. O último estudo foi realizado com o objetivo de obter uma ferramenta com estimativas de sensibilidade e especificidade similares ao BICAMS, mas que fosse designada à triagem dos pacientes que são elegíveis para ser acompanhados pelo BICAMS. Para tal participaram do primeiro estudo, 374 voluntários da comunidade e 25 pacientes com EM. No segundo e terceiro estudo, participaram 128 pacientes com EM e 602 voluntários saudáveis. Todos os estudos clínicos e com as amostras da comunidade foram realizados no período de 2013 à 2015 e contaram com a parceria em pesquisa do Instituto Brasileiro de Neuropsicologia (IBNeuro) e do Laboratório de Instrumentação e Avaliação Psicológica (LABIAP). A coleta de pacientes foi realizada no Ambulatório de Neuroimunologia do Hospital das clínicas da Faculdade de Medicina de Ribeirão Perto (FMRP-USP). Resultados: No primeiro estudo, foram mantidas 5 palavras das 15 da versão original. A razão para as modificações na lista Brasileira foram as diferenças entre a divisão silábica, extensão das palavras e presença de protótipos. Verificou-se ainda que até a quarta palavra evocada na nossa cultura em cada categoria semântica foram as mesmas que foram evocadas na língua nativa do instrumento, mas a ordem da frequência variou dentro de cada categoria, mostrando que embora existam palavras que são prototípicas às duas culturas na classificação semântica global, o contexto cultural interfere muito quando partimos para as especificidades dentro de cada classificação e categoria semântica. O MMSE-2 também apresentou estimativas de validade e precisão comum às duas culturas. No quarto estudo, as medidas do MMSE-2 que tiveram melhor relação com o BICAMS e índices de sensibilidade e especificidade parecidos foram as medidas da tarefa de evocação, atenção e cálculo, memória de histórias e codificação dígitos-símbolos. As correlações selecionadas foram aquelas classificadas em moderadas e fortes. Como segundo critério, as medidas do MMSE-2 foram comparadas às medidas do BICAMS pela curva ROC. As medidas do MMSE- 2 que tiveram especificidade e sensibilidade significativas (p<0,001) foram as elegíveis para compor o teste de triagem. Como a tarefa de codificação dígitos-símbolos é susceptível à demanda motora, optou-se pelo uso da forma oral do SDMT em conjunto. Deste modo, no nosso instrumento de triagem, normas para este instrumento foram criadas a partir da soma dos itens do MMSE-MS com o SDMT oral. Conclusão: A integração de dados desses diversos estudos evidencia cautela quanto aos procedimentos de adaptação empregados para adaptação transcultural das tarefas que são de origem verbal e semântica. Há também evidências da necessidade de instrumentos capazes de triar esses pacientes. Para tal, o MMSE-EM mostrou-se válido, preciso, com índices de sensibilidade e especificidade similares ao BICAMS, com normas ajustadas ao contexto Brasileiro. / Background: The cognitive impairment (CI) in Multiple Sclerosis (MS) has the prevalence rate from 43% to 70% and may occur from the Clinically Isolated Syndrome (CIS) to the early stages of MS. The CI in MS can advance independently of motor signs and symptoms, EDSS scores and MRI stable. In this context, the National Multiple Sclerosis Questionnaire (MSNQ) and the International Brief Cognitive Assesment for Multiple Sclerosis (BICAMS) are international tools used to screening and monitoring MS patients in care centers. Further studies and meetings provided by same committee alluded that MSNQ has several limitations for being a non-objective measure and the screening using the Symbol Digit Modalities Test (SDMT) alone is not effective because other areas that may be impaired in MS is not screened. With the second revision of the MMSE, and the lack of objective screening tools to quikly screening MS patients that needed to be monitored by BICAMS, we aimed in the presente study to create a fast measurement to screening the episodic memory, processing speed, attention and working memory from BICAMS and MMSE-2. Objective: To obtain brief a screening tool for MS (MMSE-MS) were conducted four studies using different tools: first the prototype study to development of CVLT-2 lists, adaptation, psychometric properties and normative data of BICAMS to the Braziliam context (as our gold standard), Cross cultural adaptation, psychometric properties, and normative data of MMSE-2 (the experimental tool) and the preliminary study of development of MMSE-MS. Methods: All translation and adaptation studies were conducted following the same method, as widely used in the literature. The first study consisted of conventional adaptation and prototypical norms, aiming to see which had the best estimates of equivalence between the cultures. The second study with BICAMS protocol show that MS scored significantly lower on all BICAMS tests. At the end of the study, the results were discussed with a member of the international committee to confirm the evidences of transculturality between the original and Brazilian versions. The third study consisted of Adapt, to investigate the psychometric properties and stablish normative data to the MMSE-2. Similarly to the previous study, an international judge discussed the results of the study of adaptation to identify the estimatives of transculturality. The fourth and last study was conducted in order to obtain a tool with sensitivity and similar specificity estimates BICAMS, but it was designed to screen patients who are eligible to be accompanied by BICAMS. Participated of the first study, 374 healthy volunteers and 25 patients with MS. In the second and third study participated 128 MS patients and 602 healthy volunteers. All clinical studies and community samples were carried out from 2013 to 2015 and had the partnership of the Brazilian Institute of Neuropsychology (IBNeuro) and the Laboratory of Instrumentation and Psychological Assessment (LABIAP). The collection of patients was performed at the Neuroimmunology Outpatient Clinic from Ribeirão Preto Medical School (FMRP-USP). Results: In the first study, were kept 5 words of 15 from the original American version. The reason for these changes in the Brazilian list were the differences between the syllabic division, extension of the words and the presence of prototypicall words. Was also found that until the fourth word evoked in our culture, in each semantic category were the same as those mentioned in the native language, but the order of the frequency varied within each category, indicating that although there are words that are prototypically commom between the two cultures in the overall semantic classification, the cultural context changes when we analyse the specifics prototipically words inside of each classification and semantic categories. To the second study, the BICAMS showed similar estimates of reliability and validity for current use as monitoring tool for MS in the Brazilian contexto, supporting the diagnostic validity of the Brazilian-Portuguese adaptation The normative data were satisfactory (p <0.001) in relation to the vocational status. The third study, with MMSE-2 also provided good estimates of validity and precision to the both cultures. To the fourth study, the MMSE-2 was compared to the BICAMS. The MMSE-2 tasks which had similar sensitivity and specificity to the BICAMS protocol was the recalling, attention and calculation, history memory and processing speed (Symbol Digit-coding). The selected tasks were those classified as moderate and Strong correlations. The second procedure consisted on comparisions among the MMSE-2 measurements and BICAMS using ROC curve. So, the MMSE-2 measures that had significant (p <0.001) specificity and sensitivity and similar area under the curve (ROC) were eligible to composse the screening tool. As the digit-symbol coding task is susceptible to motor demand, we decided to include the oral SDMT to the task. Thus, to get our screening tool, normative data for this instrument were created from the sum of the MMSE-MS items with oral SDMT. Conclusion: The overall of the data from these studies calls attention to the necessity of the caution to the adaptation procedures used in cross-cultural adaptation of the tasks that has verbal and semantic stimuli. There is also the need of tools abel to screening MS patients. For this, these preliminar data for MMSE-MS showed evidences of validation, similar sensitivity and and specificity, with normative data culturally adjusted to the Brazilian context.

Abstract This thesis concentrates on joint optimization of transmit power allocation and receive filtering in multiuser, multi-antenna communications. Due to the increasing number of wireless devices, the design of energy-efficient communication links is becoming increasingly important. In cellular mobile communications, reducing the average power consumption in uplink transmission is beneficial for users in order to extend battery life and, hence, energy efficiency in general. However, the power consumption of the high power amplifier (HPA) at the transmitter depends on the peak power of the transmission. This thesis focuses on power allocation problems for single-carrier (SC) frequency division multiple access (FDMA) and orthogonal FDMA (OFDMA) transmission assuming iterative reception. The goal in the first scheme presented in this thesis is to reduce the average power consumption by designing a power allocation method that takes into account the convergence properties of an iterative receiver in multiuser uplink communications. The proposed scheme can guarantee that the desired quality of service (QoS) is achieved after a sufficient number of iterations. Reducing the peak-to-average power ratio (PAPR) in any transmission system is beneficial because it allows the use of inexpensive, energy-efficient power amplifiers. The goal in the second scheme presented in this thesis is to control the PAPR of the transmitted signal. Hence, in addition to the QoS constraint, the instantaneous PAPR constraint is derived for SC-FDMA and OFDMA transmission. Moreover, a statistical approach is considered in which the power variance of the transmitted waveform is controlled. The QoS and PAPR constraints are considered jointly and, therefore, the proposed power allocation strategy jointly takes into account the channel quality and the PAPR characteristics of the power amplifier. However, the PAPR constraint can be adopted to any SC-FDMA or OFDMA framework and it is not restricted to the scheme presented in this thesis. The objective of the optimization problems considered throughout the thesis is to minimize the sum power. The majority of the derived constraints are non-convex and therefore, two alternative successive convex approximations (SCAs) are derived for all the non-convex constraints considered. The numerical results show that the proposed power allocation strategies can significantly reduce the average transmission power of users while allowing flexible PAPR control. Hence, the proposed methods can be used to extend battery life for users and especially improve the QoS at the cell edges. / Tiivistelmä Väitöskirjassa tutkitaan lähettimessä tapahtuvan tehoallokoinnin sekä vastaanottimessa tapahtuvan signaalin suodatuksen yhteisoptimointia monikäyttöön suunnatussa langattomassa moniantennikommunikaatiossa. Langattomien laitteiden lukumäärän kasvaessa energiatehokkuuden merkitys tiedonsiirtolinkkien suunnittelussa korostuu. Soluihin perustuvassa langattomassa tietoliikenteessä keskimääräisen tehonkulutuksen pienentäminen ylälinkkilähetyksessä (käyttäjältä tukiasemaan) on tärkeää käyttäjän kannalta, sillä se pidentää laitteen akun kestoa. Lähettimen tehovahvistimen (high power amplifier (HPA)) tehonkulutus on kuitenkin verrannollinen lähetyksen huipputehoon. Väitöskirjassa luodaaan uusia menetelmiä sekä vertaillaan tehoallokointia yhden kantoaallon taajuustason monikäyttöön (single carrier frequency division multiple access (SC-FDMA)) ja ortogonaalisen taajuustason monikäyttöön (orthogonal FDMA (OFDMA)) perustuvissa lähetysteknologioissa. Työn ensimmäisessä osiossa tavoitteena on keskimääräisen tehonkulutuksen pienentäminen monen käyttäjän ylälinkkikommunikaatiossa suunnittelemalla tehoallokointimenetelmä, joka ottaa huomioon iteratiivisen vastaanottimen konvergenssiominaisuudet. Työssä ehdotettu menetelmä takaa vastaanotetun informaation halutun laadun (quality of service (QoS)) riittävän monen vastaanottimessa tehdyn iteraation jälkeen. Huipputehon ja keskitehon suhteen (peak to average power ratio (PAPR)) pienentäminen missä tahansa lähetyksessä on hyödyllistä, sillä sen ansiosta voidaan käyttää energiatehokkaampia ja halvempia tehovahvistimia. Työn jälkimmäisessä osiossa tavoitteena on kontrolloida lähetetyn signaalin huipputehon ja keskitehon suhdetta. Työn ensimmäisessä osiossa esitetyn QoS-rajoitteen lisäksi tehoallokointia rajoitetaan symbolisekvenssikohtaisella PAPR-rajoitteella SCFDMA- ja OFDMA-lähetyksessä. Lisäksi esitetään tilastollinen menetelmä, jossa rajoitetaan lähetetyn signaalin tehon varianssia. Kun käytetään yhtäaikaisesti QoS- ja PAPR-rajoitteita, voidaan tiedonsiirtokanavaan suunnitella optimaalinen tehoallokointi ottaen huomioon tehovahvistimen epälineaarisuudet. Työssä esitetty PAPR-rajoite on kuitenkin geneerinen, ja se voidaan sovittaa mihin tahansa SCFDMA- tai OFDMA- optimointikehykseen. Työssä esitettävien optimointiongelmien tavoitteena on käyttäjien summatehon minimointi. Suurin osa työssä esiintyvistä ongelmista on ei-konvekseja, joten siinä esitetään kaksi vaihtoehtoista peräkkäinen konveksi approksimaatio (successive convex approximation (SCA)) -menetelmää kaikille ei-konvekseille rajoitteille. Numeeriset tulokset osoittavat, että esitetyt tehoallokointimenetelmät pienentävät merkittävästi keskimääräistä tehonkulutusta mahdollistaen lisäksi adaptiivisen PAPR-kontrolloinnin. Väitöskirjassa esitettyjen menetelmien avulla voidaan pidentää mobiilikäyttäjien akun kestoa sekä erityisesti parantaa solun reunakäyttäjien palvelun laatua.

[pt] Sistemas de múltiplas antenas livres de células surgiram recentemente como uma combinação de MIMO massivo, sistemas de antenas distribuídas (DAS) e network MIMO. Esta dissertação explora o downlink deste cenário com pontos de acesso (PAs) de uma ou múltiplas antenas e considerando conhecimento perfeito e imperfeito do canal. São desenvolvidos esquemas que combinam pré-codificação, alocação de potência e seleção de PAs (SPA). Para começar, duas estratégias de SPA foram investigadas, uma baseada em busca exaustiva (BE-SPA) e a outra em coeficientes de desvanecimento de larga escala (LE-SPA), com o intuito de reduzir a complexidade das redes livres de células. Subsequentemente, apresentamos duas técnicas iterativas de pré-codificação, todas seguindo o critério Minimum Mean-Square Error (MMSE), combinadas à restrição de potência total. A primeira nós chamamos de MMSE, com restrição de potência total. Nós também incorporamos robustez ao método desenvolvido chamado RMMSE, um pré-codificador robusto com restrição de potência total. Como terceiro elemento da configuração proposta, esquemas de alocação de potência foram desenvolvidos, com abordagens ótimas, adaptativas e uniformes. Um algoritmo de alocação de potência ótima (APO) é apresentado, baseado na maximização da mínima Signal-to-Interference-plus-Noise Ratio (SINR). A solução adaptativa (APA) é caracterizada pelo gradiente estocástico (GE) do mean-square error (MSE) e a alternativa uniforme (UPA) propõe a equalização de todos os coeficientes de potência. Todas as configurações devem respeitar a restrição de potência por antena, imposta pelo sistema. Uma análise de soma das taxas é feita, para todas as técnicas estudadas e o custo computacional de cada uma delas é calculado. Resultados numéricos provam que as técnicas propostas têm performance superior à pré-codificadores Conjugate Beamforming (CB) e Zero-Forcing (ZF), ambos com alocação de potência uniforme e ótima, na forma de taxa de erro de bit (BER), soma das taxas e mínima SINR. Além disso, os resultados atestam que o desempenho pode ser mantido e até melhorado com a aplicação de SPA. / [en] Cell-Free Massive multiple-input multiple-output (MIMO) systems have emerged in recent years as a combination of massive MIMO, distributed antenna systems (DAS) and network MIMO. This thesis explores the downlink channel of such scenario with single and multiple-antenna access points (APs) and takes into account both perfect and imperfect channel state information (CSI). We propose transmit processing schemes that combine precoding, power allocation and AP selection (APS). To begin with, two APS strategies have been investigated, one based on exhaustive search (ES-APS) and the other on the large-scale fading coefficients (LSAPS), in order to reduce the complexity of cell-free networks. Subsequently, we present two iterative precoding techniques following the minimum meansquare error (MMSE) criterion with total power constraint. The first we call MMSE, with total power constraint. We also incorporate robustness in the developed method, called RMMSE, a robust precoder with total power constraint. As the third element of the proposed schemes, power allocation techniques are developed, with optimal, adaptive and uniform approaches. An optimal power allocation (OPA) algorithm is presented based on the maximization of the minimum signal-to-interference-plus-noise ratio (SINR). The adaptive solution (APA) is characterized by the stochastic gradient of the mean-square error (MSE) and the uniform alternative (UPA) proposes to equalize all power coefficients. All configurations must fulfil an antenna power constraint, imposed by the system. A sum-rate analysis is carried out for all studied techniques and the computational cost of each one is calculated. Numerical results prove that the proposed techniques outperform existing conjugate beamforming (CB) and zero-forcing (ZF) precoders, both with uniform and optimal power allocation, in terms of bit error rate (BER), sum-rate and minimum SINR. Furthermore, we also attest that performance can be maintained or even improved in the presence of APS.

Introduction: Cognitive impairment is converted for 15% to Alzheimer’s disease (AD), which is incurable. The aim of this study is to investigate whether Herpes simplex virus type 1 (HSV1) and its interaction with allele ε4 of Apolipoprotein E (ApoE-ε4) may be possible risk factors for cognitive impairment. Here, suggestions for implementation of Precision Public Health (PPH) is also presented; population studies of relevant biomarkers of infectious burden and data from health outcomes with the aim of remedying public health crises, monitoring diseases, anticipating risks and using public health initiatives adapted to risk groups to increase understanding of diseases, such as AD. Method: An analysis of 1013 people aged 75 from the cohort, Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS), was performed. Linear mixed models (LMM) were used to investigate whether anti-HSV1 IgG and ApoE-ε4 are associated with risk of developing cognitive impairment over 5 years. Anti-HSV1 IgG in serum was detected by Enzyme-linked immunosorbent assays and cognitive impairment was examined by Mini Mental State Examination. Results: Neither anti-HSV1 IgG positivity nor its interaction with ApoE-ε4 were associated with cognitive impairment. Discussion: Studies of HSV1 without HSV2 or HSV show mixed results. Therefore, we do not yet have sufficient evidence to implement PPH-interventions against these risks. Other cognitive tests that are more sensitive to early changes and adjustment for underrepresented groups may potentially contribute to a more accurate analysis. / Bakgrund: Kognitiv nedsättning övergår för 15 % till Alzheimers sjukdom (AD) som är obotlig. Denna studie har målsättningen att undersöka om Herpes simplex virus typ 1 (HSV1) och dess interaktion med riskvarianten allel ε4 av genen Apolipoprotein E (ApoE-ε4) kan vara möjliga riskfaktorer för kognitiv nedsättning. I arbetet diskuteras även hur man genom Precision Public Health (PPH) kan studera befolkningen med avseende på relevanta biomarkörer och data från hälsoutfall med syfte att avhjälpa folkhälsokriser, övervaka sjukdomar och förutse risker såsom sjunkande kognition och med folkhälsoinsatser anpassade till riskgrupper öka förståelsen av dessa tillstånd. Metod: En analys av 1013 personer 75 år ur kohorten ”Prospecive Investigation of the Vasculature in Uppsala Seniors” (PIVUS). Linear mixed models (LMM) användes för att undersöka om anti-HSV1 IgG och ApoE-ε4 är associerade med kognitiv nedsättning under 5 år. Anti-HSV1 IgG i serum detekterades med ”Enzyme-linked immunosorbent assays” och kognitiv nedsättning undersöktes med Mini Mental State Examination. Resultat: Anti-HSV1 IgG positivitet var inte associerat med kognitiv nedsättning. Anti-HSV1 IgG positivitet och samtidig ApoE-ε4 var inte heller associerat med kognitiv nedsättning. Diskussion: Andra studier av endast HSV1 utan HSV2 eller HSV visar blandade resultat, varför kunskapsläget idag inte stödjer tillämpning av PPH-interventioner mot dessa risker. Andra kognitiva mått som är känsligare för små förändringar nära intakt kognition samt justering för underrepresenterade grupper kan möjligen bidra till säkrare analys.

[pt] Os sistemas de múltiplas entradas e múltiplas saídas (MIMO) empregam um número crescente de antenas, o que leva a relevantes consumo de energia e custo de hardware dos front-ends correspondentes. Nesse contexto, o uso de conversores analógico-digitais (ADCs) de baixa resolução é promovido como uma solução promissora para este problema. Neste estudo consideramos um receptor MIMO de baixa resolução que implica que os sinais recebidos são processados simultaneamente pelos 1-bit ADCs e pela rede comparadora. Os sinais de entrada da rede comparadora podem vir de antenas diferentes, de modo que a extensão da rede comparadora pode ser interpretada como canais virtuais com saídas binárias. Com base nesses receptores MIMO de baixa resolução, desenvolvemos um estimador de canal e detector lineares de baixa resolução baseados no critério de mínimo erro médio quadrático (LRA-LMMSE) de acordo com o teorema de Bussgang. Duas redes de comparação são propostas, nomeadas, redes total e parcialmente conectadas. Também desenvolvemos uma rede parcialmente conectada baseada em busca gananciosa que usa muito menos comparadores para obter um desempenho bem próximo ao da rede totalmente conectada. Os resultados numéricos mostram que adicionar canais virtuais pode ser melhor do que adicionar canais físicos extras que correspondem a antenas de recepção adicionais em termos de taxa de erro de bit (BER). Além disso, ao empregar o estimador de canal proposto e seu erro de estimativa correspondente, construímos um limite inferior na taxa de soma ergódica para o receptor LRA-MMSE. Os resultados de simulação mostram que os sistemas com a proposta sistemas MIMO auxiliados por rede com quantização de 1-bit no receptor superam o convencional sistema MIMO de 1-bit em termos de desempenho de BER e erro quadrático médio (MSE). Além disso, as simulações numéricas confirmam uma vantagem significativa em termos de taxa de soma para o sistema proposto. / [en] Multiple-input multiple-output (MIMO) systems employs an increasing number of antennas, which leads to relevant energy consumption and hardware cost of the corresponding front ends. In this context, the use of lowresolution analog to digital converters (ADCs) is promoted as a promising solution to this problem. In this study we consider a low-resolution MIMO receiver which implies that the received signals simultaneously are processed by the 1-bit ADCs and the comparator network. The input signals for the comparator network can come from different antennas, such that the comparator network extension can be interpreted as virtual channels with binary outputs. Based on such low-resolution MIMO receivers, we develop low-resolution aware linear minimum mean-squared error (LRA-LMMSE) channel estimator and detector according to the Bussgang theorem. Two comparator networks are proposed, namely, fully and partially connected networks. We also devise a greedy search-based partially connected network that can use much less comparators to approach the performance of the fully connected network. Numerical results shows that adding virtual channels can be better than adding extra physical channels which corresponds to additional receive antennas in terms of bit error rate (BER). Furthermore, by employing the proposed channel estimator and its corresponding estimation error, we build up a lower bound on the ergodic sum rate for the LRA-LMMSE receiver. Simulation results show that the systems with the proposed network-aided MIMO systems with 1-bit quantization at the receiver outperforms the conventional 1-bit MIMO system in terms of BER and mean-square error (MSE) performances. Moreover, numerical simulations confirm a significant advantage in terms of sum rate for the proposed system.