To achieve cooperative diversity in cognitive radio network, Decode and Forward (DF) protocol is implemented at Cognitive Radios (CRs) using Orthogonal Space Time Block Coding (OSTBC). The 2-hop communication between source and destination is completed with the help of Cognitive Relays (CRs) using Multiple Input Multiple Output (MIMO) technology within the network. To achieve spatial diversity and good code rate Alamouti 2×2 STBC is used for transmission. CR is using the decoding (Decode and Forward (DF)) strategy and without amplifying ability before forwarding data towards destination provide better performance. The main objective of this thesis is to detect Primary User (PU) spectrum availability or non-availability for the use of Secondary Users (SU). The Alamouti STBC encoded data is broadcasted to wireless Rayleigh faded channel through transmitter having two transmitting antennas. The CRs are preferred to place close with PU to detect transmitted signal and because of having decoding capability CRs decode the collected data using Maximum Likelihood (ML) decoding technique then re-encode the decoded data for further transmission towards receiver. The energy of PU signal received at relays is calculated using energy detector used at cognitive controller having authority to make final decision about presence or absence of PU signal within the spectrum by comparing calculated energy of PU received signal with a predefined value. If the calculated signal energy is less than threshold value it is pretended as the absence of PU and in the other case spectrum is assumed as occupied by PU. Decoding PU signal at relays before forwarding towards destination provide better performance in terms of detection probability and decreasing probability of false alarming as the Signal to Noise (SNR) increases. The proposed cooperative spectrum sensing using DF protocol at cognitive relays with Alamouti STBC is implemented and results are validated by MATLAB simulation. / +46 455 38 50 00

In this report, we introduce cooperative spectrum sensing using orthogonal space time block coding (OSTBC) in order to achieve cooperative diversity in the cognitive radios (CRs) network. Transmit diversity or gain is achieved by introducing more than one antenna on the transmitter and receiver side, but in small electronic mobile devices it looks impractical. The signals received from the primary users (PUs) are amplified by the cognitive relays and further forwarded to the cognitive controller where decisions are made on the basis of the information collected from each cognitive relay. The cooperative relaying protocol used here in cognitive relays is based on an amplifying-forward (AF) scheme. Alamouti scheme in OSTBC has been proposed to achieve better detection performance in CR network. The energy detector performance is analyzed over an independent Rayleigh fading channel. In CR network the secondary user (SU) shares PU's frequency band if it fi nds PU is not in its vicinity. The SU starts using the licensed band and leaves the band as soon as it finds the PU is present or going to use the same band. The detection of the spectrum holes by CRs has to be more agile and intelligent. The main objective of the CRs network is to use the free holes without causing any interference to the PUs. The energy detection technique is simple and outperforms other sensing techniques in cooperative cognitive radio networks. The energy detector collects information from different users, compares it with a certain prede fined threshold () value and then makes a fi nal decision. Detection and false alarm probabilities are derived and manipulated using OSTBC on PU and SU through AF protocol in cooperative communication. The performance of the system is analyzed with single and multiple relays and with and without direct path between the PUs and SUs. Maximum ratio (MRC) and selection combining (SC) schemes are used in energy detector and the results are compared with and without direct link between PU and SU. The analysis is performed by placing the relay close to the PUs. Our results are processed and validated by computer simulation.

High data rate applications are the trend in today's wireless technology. W-CDMA standard was designed to support such high data rates of up to 3.84 Mcps. The main purpose of this research was to analyze the feasibility of a fixed-point implementation of the W-CDMA downlink receiver algorithm on a general-purpose digital signal processor (StarCore SC140 by Motorola). The very large instruction word architecture of SC140 core is utilized to generate optimal implementation, to meet the real time timing requirements of the algorithm. The other main aim of this work was to study and evaluate the performance of the W-CDMA downlink structure with incorporated space-time transmit diversity. The effect of the channel estimation algorithm used was extensively studied too.

À l'échelle de la planète, les milieux humides représentent entre 4 et 6 % de la superficie des terres émergées. Au Canada, cette proportion atteint près de 15 %. Ces écosystèmes, dont l'hydrologie est étroitement liée à l'hydrogéologie de surface, sont fragiles et essentiels au maintien de la biodiversité. Le présent projet de maîtrise est réalisé dans le cadre d'un projet de caractérisation des eaux souterraines financé par le MDDEP et a pour objectif principal de comprendre le rôle des tourbières dans la dynamique de l'aquifère de la partie basse de la zone Bécancour. Une cartographie de l'ensemble des tourbières du territoire a été réalisée et leur degré de perturbation a été déterminé par photo-interprétation. La même démarche a été entreprise pour les photos aériennes de 1966, afin de connaître l'évolution des superficies dans le temps. Les résultats montrent qu'il y a 10 485 ha de tourbières intactes et 7 015 ha de tourbières légèrement perturbées. Les perturbations les plus fréquentes sont les canaux de drainage et les chemins forestiers. De plus, 5 433 ha de tourbière ont subi des perturbations irréversibles entre 1966 et 2010 sur la partie basse de la zone Bécancour, principalement en lien avec l'exploitation de la canneberge. Le contexte géomorphologique de neuf tourbières a été étudié au moyen de sondages manuels, de levés géophysiques par géoradar et d'analyses granulornétriques. Les résultats montrent que les tourbières de la zone d'étude reposent toutes sur un substrat au moins partiellement perméable. Les substrats des tourbières à l'étude sont composés à 44 % sur un substrat de sable éoliens et de till remanié, à 33 % sur un dépôt de till remanié, à 11 % sur un dépôt deltaïque et de till remanié et à 11 % sur un dépôt marin et de till remanié. Les neuf tourbières étudiées ont une profondeur maximale variant entre 1,63 et 6,40 m et une profondeur moyenne entre 1,10 et 2,94 m. Les flux entrants et sortants des neuf sites ont été quantifiés à l'aide de l'approche segmentée de l'équation de Darcy. Les flux échangés entre les tourbières et l'aquifère se situent entre -1097 et 409 m3/j, cinq sites alimentant l'aquifère, trois sites recevant l'eau de l'aquifère et un n'ayant pas d'échange entre les milieux. Représentant en moyenne entre 4 et 11 % des apports totaux de la tourbière, il a été possible d'extrapoler à l'ensemble des tourbières, et d'estimer les flux transitant entre les deux milieux à l'échelle de la zone d'étude. Le flux transitant de l'aquifère vers la tourbière est estimé entre 0,0033 et 0,0099 rn3/s et le flux de la tourbière vers l'aquifère est estimé entre 0,0056 et 0,0168 m3/s. Ces proportions suggèrent que la tourbière joue un rôle tampon relativement limité. Localement, ces flux permettent de garder les niveaux piézométriques relativement stables en redistribuant l'eau au système du surface ou souterrain. ______________________________________________________________________________

L’étude de dimensionnement d’un réseau cellulaire est une phase de conception qui doit permettre de déterminer les performances d’un système dans une configuration donnée. Elle inclut l’étude de couverture et l’analyse de trafic. De complexes simulations sont possibles pour connaître les paramètres de performances d’un réseau mais seules les études analytiques fournissent des résultats rapides. Par ailleurs, pour faire face à la demande de hauts débits, à la rareté du spectre fréquentiel et à l’impossibilité d’émettre à de plus fortes puissances, de nouvelles techniques de transmissions sont apparues. Nous sommes ainsi passés d’un système classique à une seule antenne à des systèmes à multiple antennes et même à des scénarios de coopération entre stations de base. Dans cette thèse, nous proposons des modèles analytiques pour l’étude des performances, notamment en termes de probabilités de coupure, de ces évolutions des réseaux cellulaires. Dans une première phase, nous considérons des systèmes multicellulaires à une antenne émettrice et une antenne réceptrice (SISO). Nous proposons deux méthodes d’étude de l’impact conjoint de l’affaiblissement de parcours, de l’effet de masque et des évanouissements rapides. Nous étudions, par la suite, un système à large bande utilisant le retournement temporel comme technique de transmission. Dans une deuxième phase, nous considérons des systèmes multicellulaires à antennes multiple à l’émission ou à la réception (MISO/MIMO) implémentant les schémas de diversité Alamouti et de combinaison par rapport maximal (MRC). Ensuite, nous considérons un système multicellulaire multi-utilisateurs à précodage de forçage à zéro (ZFBF). / The implementation of cellular systems have aroused issues related to the design of cellular networks termed to as network dimensioning. It includes the coverage estimation and thetraffic analysis. Simple models and methods are required to reduce the time consumption of these two analysis. At the same time, the growing demand for higher data rates constrained by the scarcity of frequency spectrum, and the requirements in terms of power consumption reduction make the telecommunication community think about new transmission techniques moving from the classical single antenna systems to multiple antenna systems and even the newly envisaged cooperative systems. In this thesis, we provide analytical models to assess the performance of these different cellular network evolutions in terms of outage probabilities. In a first study, we consider multicellular single input single output (SISO) systems. First, we propose two accurate methods to study the joint impact of path-loss, shadowing and fast fading. This system has so far been studied either considering the only impact of path-loss and Rayleigh fading, or considering the same channel model as in our case but providing very complex outage probability expressions. Then, we provide an outage probability expression in a wideband communication context implementing the Time Reversal (TR) transmission technique considering the impact of fast fading. In a second study, we focus on multiple antenna systems. We study the performance of a Multiple Input Multiple Output (MIMO) system implementing a transmit and a receivediversity schemes namely the Alamouti code and the Maximum Ratio Combining (MRC).

Multiple Input and Multiple Output (MIMO) is one of the techniques used tiimprove the system performance. In this thesis, we improve and evaluate the system performance of MIMO deploying MRT technique at the transmitter and MRCtechnique at the receiver with an assuming that the system can obtain perfect CSI.We derived expressions for outage probability and symbol error rate and simulationgraphs for SISO, SIMO, MISO, and MIMO in terms of outage probability. Our results show that the MIMO system performance is better than other configurations.We also observed that SISO have the least performance where SIMO and MISOhave same performance. The performance also increases as the number of antennasincrease in the system and it is suggested to use MIMO when performance is givehigh priority than cost.

Thesis advisor: Xiaoxiang Peter Zhang / Thesis advisor: James P. Morken / Diazomalonates have been demonstrated, for the first time, as effective radical precursors for asymmetric radical cyclopropanation of alkenes via Co(II)-based metalloradical catalysis (MRC). With an optimized D2-symmetric chiral amidoporphyrin as the supporting ligand, the Co(II)-based metalloradical system can efficiently activate unsymmetrical methyl phenyl diazomalonate (MPDM) for the asymmetric cyclopropanation of alkenes, enabling stereoselective construction of 1,1-cyclopropanediesters bearing two contiguous chiral centers, including at least one all-carbon quaternary stereogenic center. The Co(II)-catalyzed asymmetric cyclopropanation, which operates at room temperature without slow addition of the diazo compound, is generally applicable to a broad range of olefin substrates and tolerates various functionalities, providing a streamlined synthesis of chiral 1,1-cyclopropanediesters in high yields with high level of control in both diastereoselectivity and enantioselectivity. Mechanistic studies on the cyclopropanation reactions, including the use of (E)- and (Z)-b-deuterostyrenes, support the underlying stepwise radical pathway for the Co(II)-catalyzed cyclopropanation. In addition to functioning as effective 1,3-dipoles for stereospecific formation of five-membered ring structures, the resulting enantioenriched methyl phenyl (E)-1,1-cyclopropanediesters serve as useful building blocks for the synthesis of different 1,1-cyclopropanediesters, 1,1-cyclopropaneestercarboxylic acids and 1,1-cyclopropaneesteramides while maintaining the original stereochemistry. Additionally, the enantioenriched (E)-1,1-cyclopropanediesters can be converted to (Z)-diastereomers without affecting the high enantiopurity. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

No description available.

Os objetivos deste trabalho foram: comparar a força muscular (FM) e as habilidades motoras de pacientes com Distrofia Muscular de Duchenne (DMD) em corticoterapia com a evolução natural da doença (Scott, 1982) e identificar a idade ideal de início da corticoterapia. Noventa pacientes com DMD em seguimento ambulatorial no Hospital das Clínicas da Faculdade de Medicina da USP, submetidos à corticoterapia (deflazacort ou prednisolona) por um período variável de um a sete anos, foram avaliados quanto à FM através da escala MRC e quanto às habilidades motoras através da escala Hammersmith motor ability score. Foram incluídos no estudo todos os pacientes com idade entre cinco e 12 anos, que compreendiam comandos verbais e que não haviam sido submetidos a cirurgias ortopédicas corretivas ou interrompido em algum momento a corticoterapia. A relação entre FM e habilidades motoras, a comparação dos dados com aqueles do estudo de Scott et al. e a análise da influência do tempo de tratamento, da idade de início e da idade na avaliação, sobre os valores obtidos nos testes foram submetidas a tratamento estatístico. Concluiu-se que: a progressão da perda da FM e das habilidades motoras em relação à idade foi mais lenta do que a da evolução natural em todas as faixas etárias avaliadas; quanto maior a idade maior a diferença entre os dois estudos; a perda da FM foi mais intensa do que a perda da funcionalidade; a metodologia utilizada não permitiu estabelecer com clareza a influência da idade de início do tratamento sobre os parâmetros avaliados, porém demonstrou a influência positiva do tempo de tratamento sobre a FM e habilidades motoras. / The aims of this study were: to compare muscle strength (MS) and motor abilities of Duchenne Muscular Dystrophy (DMD) patients in use of steroids, with the natural evolution of the disease (Scott, 1982) and to identify the ideal age for starting on steroid therapy. Ninety patients with DMD followed as outpatients at the Clinics Hospital of the University of São Paulo School of Medicine and submitted to steroid therapy (deflazacort or prednisolone) for a period of one to seven years were assessed for MS using the MRC scale, and for motor abilities with the motor ability score from the Hammersmith scale. All patients aged between five and 12 years who understood verbal commands and who had not been submitted to corrective orthopedic surgery and had no interruption in steroid therapy, were included in the study. Statistical analysis was carried out to assess the relationship between MS and motor abilities and to compare our data against results of Scott\'s study. The influence of length of treatment, age at disease onset and first assessment, on values obtained in the tests was investigated. We concluded that: the progression in loss of MS and of motor abilities with age was slower than the natural evolution across all age groups studied; the higher the age the greater the difference between the two studies; loss of MS was more intense than loss of functionality; the methodology used was unable to clearly ascertain the influence of age at treatment on the parameters assessed, but a positive influence of length of treatment on both MS and motor abilities was identified.

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.