Cette thèse s'est déroulée dans le cadre d'un contrat CIFRE entre l'université de Paris Est Marne la Vallée et Freescale Semiconductor sur son site basé à Toulouse. Le sujet principal a été l'étude de la liaison descendante de systèmes de télécommunication disposant de plusieurs antennes d'émission et de réception et équipés d'un récepteur de Wiener plus généralement appelé récepteur MMSE (Minimum Mean Squared Error).

New high quality mobile telecommunication services are offered everyday and the demand for higher data rates is continuously increasing. To maximize the uplink throughput in HSPA when transmission is propagated through a dispersive channel causing self-interference, equalizers are used. One interesting solution, where the equalizer and decoder exchange information in an iterative way, for improving the equalizer performance is Turbo equalization. In this thesis a literature survey has been performed on Turbo equalization methods and a chosen method has been implemented for the uplink HSPA standard to evaluate the performance in heavily dispersive channels. The selected algorithm has been adapted for multiple receiving antennas, oversampled processing and HARQ retransmissions. The results derived from the computer based link simulations show that the implemented algorithm provide a gain of approximately 0.5 dB when performing up to 7 Turbo equalization iterations. Gains up to 1 dB have been obtained by disabling power control, not using retransmission combining and utilizing a single receiver antenna. The algorithm has also been evaluated considering alternative dispersive channels, Log-MAP decoding, different code rates, number of Turbo equalization iterations and number of Turbo decoding iterations. The simulation results do not motivate a real implementation of the chosen algorithm considering the increased computational complexity and small gain achieved in a full featured receiver system. Further studies are needed before concluding the HSPA uplink Turbo equalization approach.

A Quick Test (AQT) Färg och Form är ett test av snabb automatiserad benämning avsett att detektera kognitiva störningar. Det består av tre delar som var och en utgörs av 40 visuella stimuli som skall benämnas så snabbt som möjligt. Tidigare studier har indikerat att AQT skiljer personer med Alzheimers sjukdom från friska kontroller med högre precision än det ofta använda Mini-Mental-Testet (MMT). I denna studie undersöktes för första gången om AQT-resultat kunde predicera diagnosen hos en konsekutiv serie patienter vid en minnesklinik samt relationen mellan AQT-resultat och biomarkörer (likvorproteiner) för neurodegenerativ sjukdom. 492 svarsblanketter från AQT Färg och Form analyserades och diagnostisk prediktion samt korrelation med nivån av likvorproteiner fastställdes för de 374 första patienterna i serien. Resultaten tyder på att AQT Färg och Form kan vara känsligt för vissa lindriga kognitiva sviktsymptom som förekommer hos personer remitterade för minnesbesvär men inte alltid känsligt för lindriga grader av demens. AQT-data korrelerade måttligt med nivån av patologiska likvorproteiner, troligen avspeglande förhöjda nivåer i Alzheimergruppen. Ytterligare forskning på konsekutiva fallserier behövs för att fastställa testets diagnostiska diskriminationsförmåga i klinisk praxis. / A Quick Test (AQT) Color-Form is a test that uses rapid automatized naming in order to identify cognitive impairment. It is divided into three parts, each of which consists of 40 stimuli that are to be named as quickly as possible. Previous studies have indicated that AQT separates patients with Alzheimer’s disease from normal controls with higher accuracy than the commonly used Mini-Mental State Examination (MMSE). The purpose of this study was to investigate, for the first time, whether AQT results collected from a consecutive series of patients at a Memory Clinic would be able to predict the diagnosis. Another aim was to study the possible relation between AQT results and Cerebrospinal Fluid (CSF) biomarkers for neurodegenerative diseases. 492 forms from AQT Color-Form tests were analyzed and diagnostic prediction and correlation with level of CSF biomarkers were determined for the first 374 patients. The results imply that AQT Color-Form may be sensitive to some symptoms of benign memory impairment that is found in patients admitted to a Memory Clinic, but that it is not always sensitive to mild degrees of dementia. Further research consecutive series of patients is needed in order to determine the diagnostic abilities of discrimination in clinical practice.

In this thesis, we study the performance of an antenna switching (AS) system in comparison to an Alamouti coded system. We analyze the outage probabilities and propose minimum mean-squared error based iterative equalizers for both systems. We see from the outage probability analysis of both systems that the AS system may achieve the same diversity order of the Alamouti coded scheme contingent on the transmission rate and constellation size. In the proposed receiver, MMSE equalization and channel decoding are jointly carried out in an iterative fashion. We use both hard and soft decision channel decoders in our simulations. It is observed that the Alamouti based scheme performs better when the channel state information is perfect. The Alamouti scheme also performs better than the AS scheme when the channel state information is imperfect in hard decision channel decoder case and a random interleaver is used. On the other hand, if a random interleaver is not used, AS scheme performs remarkably better than the Alamouti scheme in hard decision channel decoder case. In a soft decision channel decoder case, when the channel state information is imperfect, the AS scheme performs approximately a 2 dB better than the Alamouti scheme. Moreover, there is approximately a 3 dB performance gain if a soft decision channel decoder is used instead of hard decision.

No description available.

The aging brain is characterized by alteration in synaptic contacts, which leads to decline of motor and cognitive functions. These changes are reflected in the age related shifts in power spectrum of electroencephalogram (EEG) signals in both wakefulness and sleep. Various non-linear measures have been used to obtain more insights from EEG analysis compared to the conventional spectral analysis. In our study we used Sample Entropy to quantify regularity of the EEG signal. Because elderly subjects arouse from sleep more often than younger subjects, we hypothesized that Entropy of EEG signals from elderly subjects would be higher than that from middle aged subjects, within a sleep stage. We also hypothesized that the entropy increases during and following an arousal and does not return to background levels immediately after an arousal. Our results show that Sample Entropy varies systematically with sleep state in healthy middle-aged and elderly female subjects, reflecting the changing regularity in the EEG. Sample Entropy is significantly higher in elderly in sleep Stage 2 and REM, suggesting that in these two sleep stages the cortical state is closer to wake than in middle-aged women. Sample Entropy is higher in post-arousal compared to the pre-arousal and stays high for a 30 sec period.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Em se tratando de comunicaÃÃes mÃveis, a troca de informaÃÃes sobre os estados do canal entre as antenas receptoras e transmissoras à uma importante ferramenta para a melhoria do desempenho do sistema. Assim, nesse trabalho foram analisados sistemas MIMO multiplexados espacialmente, Spatially Multiplexed MIMO (SM-MIMO), com informaÃÃes do estado do canal no transmissor, Channel State Information (CSI), limitadas e duas tÃcnicas de detecÃÃo linear do sinal e prÃ-equalizaÃÃo do sinal Zero Forcing (ZF) e Minimum Mean Square Error (MMSE). Para essa limitaÃÃo dois esquemas foram considerados: Quantization Codebook (QC) e Compressive Sensing (CS). Compressive Sensing à usado para gerar um CSI comprimido a ser enviado pelas antenas receptoras por um canal de feedback a fim de reduzir a quantidade de informaÃÃo enviada pelas mesmas. Portanto, nesse trabalho, o desempenho das duas tÃcnicas foram comparadas por simulaÃÃes computacionais das curvas da taxa de erro de bit, Bit Error Rate (BER), de acordo com a variaÃÃo da relaÃÃo sinal ruÃdo, Signal to Noise Ratio (SNR), considerando as duas abordagens QC e CS. AlÃm disso, a presenÃa do erro de quantizaÃÃo e do ruÃdo, no canal de feedback, tambÃm foi avaliada para o esquema de CS. / Concerning to mobile communications, the information exchange over the channel states between receiving antennas and transmiting antennas is an important tool to enhance the system performance. Thus, in this work, spatially multiplexed MIMO (SM-MIMO) systems with limited Channel State Information (CSI) were analyzed considering two techniques of linear signal detection and pre-equalization Zero Forcing (ZF) and Minimum Mean Square Error (MMSE). Due to this limitation two schemes were considered: Quantization Codebook (QC) e Compressive Sensing (CS). Compressive Sensing is used to generate a reduced CSI feedback to the transmitter in order to reduce feedback load into the system. Therefore, in this work, the performance of the techniques were compared by computational simulations of Bit Error Rate (BER) curves according to the variation of the Signal to Noise Ratio (SNR) for the two considered approaches QC and CS. Furthermore, the presence of quantization error and noise, in the feedback link, were also evaluated for the CS scheme.

O transtorno cognitivo no idoso acarreta repercussões na sua vida, na família e na relação com a sociedade. Um instrumento de avaliação cognitiva amplamente utilizado é o MEEM - Mini Exame do Estado Mental - que é um teste de rastreamento com o objetivo de selecionar pessoas com provável déficit cognitivo. Uma amostra representativa da população de 394 idosos do município de Batatais SP foi avaliada através de inquérito domiciliar em relação às condições socioeconômicas e de saúde, e foi feito rastreamento dos sintomas depressivos e do desempenho cognitivo através de um instrumento baseado no MEEM. A maioria dos entrevistados era do sexo feminino (66%), sendo que 75,4% dos idosos pertenciam a uma faixa etária de 60-74 anos, chamada idoso jovem. Com relação à escolaridade a grande maioria (62.2%) cursou o primeiro grau. Com relação aos analfabetos 77,1% eram mulheres e 22,9% eram homens. Para o estado conjugal a diferença foi na proporção da viuvez 80.2% para o sexo feminino e 19.8% para o masculino. Quanto à renda familiar, 43.7% da população recebiam menos de 2,5 salários mínimos. Para avaliação do desempenho cognitivo usou um ponto de corte ? a 23 para o MEEM. Observou-se que 81.7% ficaram acima deste ponto e 18.3% ficaram abaixo. Os idosos que tiveram os escores mais elevados foram associados aos fatores como idade (60-69 anos), maior nível escolaridade, ter hábito de leitura, ter boa relação social principalmente com parentes, não ter hipertensão arterial, diabete, incontinência urinária, catarata e ausência de sintomas depressivos. / The cognitive impairment in the old has its effects on their lives, families and relationships with society. A widely used instrument of cognitive assessment is the MMSE- Mini Mental State - that is a screening test whose aim is to select people with probable cognitive deficiency. A significant sample of the population of 394 old people from Batatais - SP, was evaluated through a home survey considering the socioeconomic and health conditions and a screening of depressive symptoms and cognitive performance was done through an instrument based on MMSE. The great majority of people who were interviewed were female (66%) and 75.4% of the old belonged to an age group from 60 to 74 years old, being considered \"younger old\". Regarding scholarship, most of them had attended primary school (62.2%). Considering the illiterate 77.1% were women and 22.9% were men. Concerning marital status a huge difference between the proportion of widows (80.2%) and widowers (19.8%) was found. With reference to familiar income 43.7% of the population earned less than 2.5 minimum wages. To evaluate the cognitive performance a cut off ? 23 for MMSE was used. It was observed that 81.7% of the old were above and 18.3% were under this point. The old who achieved the highest scores had factors such as age (60-69 years old), better scholarship level, reading habits, a good social relationship (mainly with relatives), no high blood pressure, no diabetes, no urinary incontinence, no cataract and absence of depressive symptoms.

The objective of Diploma thesis is design of analysis tool for equalizers used in FMT modulation. The model of transmission channel was designed for simulations with FMT. The transmission path is modeled by test loop, which corresponds to DSL line. For this reason, some principles of DSL technology is described in the thesis. The principles of multicarrier modulation are introduced in first part. The multicarrier modulation with filter bank (FMT) is described in detail.The different methods of design the fiter bank are given and compared. Channel equalization are introduced in second part. The attention was focused on minimum mean square error filtering (MMSE). Decision feedback channel equalizer (DFE) is extended from linear MMSE equalizer. DFE equalizers were programmed in analysis tool. For computation of equalizer coeficients was used also equalizers based on adaptive algorithms and MMSE. The last part describes the results of DFE equalizers used in communication system with FMT modulation. Analysis tool was programmed in MATLAB with a graphical user interface. It allows to show mean square error, signal-to-noise ratio and transmission speed dependence on delay between original and distorted signal. Signal-to-noise ration is displayed also in individual subchannels and users can display mean square error dependence on different orders of DFE filters.

Massive MU-MIMO (Multiuser-Multiple Input and Multple Output) is a promising technology for 5G wireless communications because of its spectrum and energy efficiency. To combat the distortion from multipath fading channel, the acquisition of channel state information is essential, which generally requires the training signal that lowers the data rate. In addition, coarse quantization can reduce the high computational energy and cost, yet results in the loss of information. In this thesis, an iterative decision feedback receiver, including iterative Channel Estimation (CE) and equalization, is constructed for a Massive MU-MIMO uplink system. The impact of multipath distortion and coarse quantization can be gradually reduced due to the iterative structure that exploits extrinsic feedback to improve the CE and data detection, so that the data rate is improved by reducing training signals for CE and by using low precision quantization. To observe and evaluate the convergence behaviour, an Extrinsic Information Transfer (EXIT) chart method is utilized to visualize the performance of the iterative receiver. / Graduate