Thesis (MscAgric (Viticulture and Oenology))--University of Stellenbosch, 2006. / Under certain South African conditions, Redglobe develops a colour that is too dark and thus unacceptable for the Far Eastern markets. These markets require a pink colour instead of a dark red colour. The cultivation of grapes with an acceptable colour involves amongst other, canopy management practices. This generally includes the removal of leaves and/or lateral shoots. Hereby, the leaf area and the microclimatic conditions in the canopy are altered. The aim of this study was to test the usefulness of leaf and lateral shoot removal at different defoliation times after anthesis in order to obtain a pink coloured Redglobe crop. Other quality aspects, namely total soluble solids (TSS), total titratable acidity (TTA), berry mass and total yield, were also evaluated. A canopy management trial was conducted on six year old Redglobe vines with moderate vigour. The treatment design was a 2 x 3 x 4 factorial and involved two leaf removal (L) levels (L0 = 0% leaf removal; L33 = 33% leaf removal) in combination with three lateral shoot removal (LS) levels (LS0 = 0 % lateral shoot removal; LS50 = 50% lateral shoot removal; LS100 = 100% lateral shoot removal). Four defoliation times (DT) were selected: 36 (pea berry size), 69 (véraison), 76 (one week after véraison) and 83 (two weeks after véraison) days after anthesis (DAA). A total of 24 treatment combinations, replicated in four blocks, were applied. Generally, treatment combinations involving 33% leaf removal lowered the main shoot leaf area. Likewise, the lateral shoot leaf area was decreased by increasing levels of lateral shoot removal at any defoliation time. As expected, 33% leaf removal applied in combination with any level of lateral shoot removal, always resulted in a lower total vine leaf area compared to where 0% leaf removal was part of the treatment combination. Compensation reactions occurred and in this regard the main shoot leaf size increased due to 33% leaf removal applied at 1 week after véraison and 2 weeks after véraison. Treatment combinations involving lateral shoot removal increased the ratio of main shoot leaf area to the total leaf area. On the other hand, the main shoot leaf area percentage was lowered by the application of 33% leaf removal at 2 weeks after véraison compared to no leaf removal at the same defoliation time. It can therefore be assumed that the contribution of lateral shoot leaves to grape composition might have increased in cases where the main shoot leaf area was lowered at a later stage (e.g. 2 weeks after véraison). The bunches were visually evaluated and divided into classes from dark (class one) to light (class nine). This visual bunch evaluation showed that the mean bunch colour was in class three (lighter than class two) due to the defoliation time. The lateral shoot removal x leaf removal interaction resulted in a mean bunch colour that was in classes 2 and 3. However, within these classes, there was a tendency that bunch colour decreased for defoliation times later than pea berry size. The lateral shoot removal x leaf removal interactions showed that bunch colour was darker when the treatment combinations involved 0% leaf removal. The percentage of bunches with the desired colour was increased by application of the treatments at véraison, compared to the other defoliation times, and also with 50% lateral shoot removal and 100% lateral shoot removal compared to 0% lateral shoot removal. Biochemical analyses confirmed that increased levels of lateral shoot removal generally lowered the anthocyanin concentration regardless of defoliation time. A similar effect on TSS was observed, i.e. from véraison onwards, the application of 50% lateral shoot removal and 100% lateral shoot removal tended to lower TSS. The effect of these levels of lateral shoot removal at véraison was significant. The role of the lateral shoots in colour development and sugar accumulation is therefore emphasized. Furthermore, the special role that lateral shoots also play in berry development is illustrated in that berry mass tended to decrease when 100% lateral shoot removal in combination with 33% leaf removal and 100% lateral shoot removal in combination with 0% leaf removal were applied at véraison. This, together with the positive relationship obtained between grape colour and the lateral shoot leaf area:fruit mass ratio, accentuates the role of active leaf area during the ripening period. The possible effect of the microclimatic light environment on colour must also be considered. However, although the light intensity increased with increased levels of LS, the colour that was obtained was probably not associated with the differences in light intensity. It was found that it is possible to manipulate the colour of Redglobe grapes with defoliation treatments. However, the treatments that have a decreasing effect on grape colour also affected other quality parameters like TSS and berry size negatively. Although, it is possible to reduce the colour of Redglobe through the application of leaf and lateral shoot removal at different defoliation times, the question arises whether the treatment combinations used in this study are worthwhile to pursue because the mean bunch colour that was obtained was still too dark. However, it was possible to increase the percentage of bunches with the desired colour. Therefore, if such treatments are applied, it must be approached cautiously, keeping in mind that assimilate supply has to be sustained throughout the ripening period.

The objectives of this work were to investigate, design and implement Multiple-Input Multiple-Output (MIMO) antenna arrays for mobile phones. Several MIMO antennas were developed and tested over various wireless-communication frequency bands. The radiation performance and channel capacity of these antennas were computed and measured: the results are discussed in the context of the frequency bands of interest. A comprehensive study of MIMO antenna configurations such as 2 × 1, 3 × 1, 2 × 2 and 3 × 3, using polarisation diversity as proposed for future mobile handsets, is presented. The channel capacity is investigated and discussed, as applying to Rayleigh fading channels with different power spectrum distributions with respect to azimuth and zenith angles. The channel capacity of 2 × 2 and 3 × 3 MIMO systems using spatial polarisation diversity is presented for different antenna designs. The presented results show that the maximum channel capacity for an antenna contained within a small volume can be reached with careful selection of the orthogonal spatial fields. The results are also compared against planar array MIMO antenna systems, in which the antenna size considered was much larger. A 50% antenna size reduction method is explored by applying magnetic wall concept on the symmetry reference of the antenna structure. Using this method, a triple dual-band inverted-F antenna system is presented and considered for MIMO application. Means of achieving minimum coupling between the three antennas are investigated over the 2.45 GHz and 5.2 GHz bands. A new 2 2 MIMO dual-band balanced antenna handset, intended to minimise the coupling with the handset and human body was proposed, developed and tested. The antenna coupling with the handset and human hand is reported in terms the radiation performance and the available channel capacity. In addition, a dual-polarisation dipole antenna is proposed, intended for use as one of three collocated orthogonal antennas in a polarisation-diversity MIMO communication system. The antenna actually consists of two overlaid electric and magnetic dipoles, such that their radiation patterns are nominally identical but they are cross-polarised and hence only interact minimally.

To support the continuously increasing number of mobile telephone users around the world, mobile communication systems have become more advanced and sophisticated in their designs. As a result of the great success with the second generation mobile radio networks, deployment of the third and development of fourth generations, the demand for higher data rates to support available services, such as internet connection, video telephony and personal navigation systems, is ever growing. To be able to meet the requirements regarding bandwidth and number of users, enhancements of existing systems and introductions of conceptually new technologies and techniques have been researched and developed. Although new proposed technologies in theory provide increased network capacity, the backbone of a successful roll-out of a mobile telephone system is inevitably the planning of the network’s cellular structure. Hence, the fundamental aspect to a reliable cellular planning is the knowledge about the physical radio channel for wide sets of different propagation scenarios. Therefore, to study radio wave propagation in typical Australian environments, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Australian Telecommunications Cooperative Research Centre (ATcrc) in collaboration developed a cellular code division multiple access (CDMA) pilot scanner. The pilot scanner measurement equipment enables for radio wave propagation measurements in available commercial CDMA mobile radio networks, which in Australia are usually deployed for extensive rural areas. Over time, the collected measurement data has been used to characterise many different types of mobile radio environments and some of the results are presented in this thesis. The thesis is divided into an introduction section and four parts based on peer-reviewed international research publications. The introduction section presents the reader with some relevant background on channel and propagation modelling. Also, the CDMA scanner measurement system that was developed in parallel with the research results founding this thesis is presented. The first part presents work on the evaluation and development of the different revisions of the Recommendation ITU-R P.1546 point-to-area radio wave propagation prediction model. In particular, the modified application of the terrain clearance angle (TCA) and the calculation method of the effective antenna height are scrutinized. In the second part, the correlation between the smallscale fading characteristics, described by the Ricean K-factor, and the vegetation density in the vicinity of the mobile receiving antenna is investigated. The third part presents an artificial neural network (ANN) based technique incorporated to predict path loss in rural macrocell environments. Obtained results, such as prediction accuracy and training time, are presented for different sized ANNs and different training approaches. Finally, the fourth part proposes an extension of the path loss ANN enabling the model to also predict small-scale fading characteristics.

This thesis describes the use of a multi-amplitude minimum shift keying (MAMSK) signal in various types of wireless communication system. A MAMSK signal is a bandwidth efficient modulation scheme obtained by superimposing ℳ minimum shift keying (MSK) signals with unequal amplitudes. The overall phase of a MAMSK signal is controlled by the phase of the largest component MSK signal which allows the use of a low-complexity differential detector. A closed form expression for the average bit error rate (BER) for coherent detection of an MAMSK in AWGN is derived and is shown to achieve the same BER as that of square constellation quadrature amplitude modulation (QAM) with the same average transmit power. We describe the design and implementation of a STBC-based MIMO radio system in conjunction with MAMSK modulation. The proposed system provides high capacity data transmission by carrying information not only in the phases but also in the amplitude. Despite using a simple MAMSK differential receiver the system achieves performance within 1 dB of coherent detection. The existing MSK modems in conjunction with STBC could easily be modified to construct the proposed system. The MAMSK modulation scheme is extended to a multiuser relaying network where two nodes cooperate in a half-duplex environment to achieve diversity gain. The cooperative scheme is based on superposition modulation using a decode-and-forward (DF) strategy. In the proposed scheme, each node simultaneously transmits its own and the relayed signals by superimposing one on the other. A MAMSK signal is an excellent choice for this type of cooperative communication due its being obtained by a superposition technique. The proposed system exploits the overall phase of a MAMSK signal which allows differential detection and as a result it provides the lowest decoding complexity and memory requirements among the existing superposition based cooperation schemes. The performance of the system is evaluated by simulation, where it is shown that the MAMSK cooperative system outperforms a conventional DF scheme in terms of both power and bandwidth efficiency.

[pt] As variações que ocorrem na estrutura da troposfera ao longo do tempo em relação à sua condição mediana provocam diversos fenômenos que fazem variar aleatoriamente o nível de sinal recebido num enlace rádio. Estas variações aleatórias são denominadas desvanecimentos. Os desvanecimentos são normalmente classificados em rápidos e lentos. Os desvanecimentos rápidos estão geralmente associados ao efeito de multipercurso atmosférico que é fortemente dependente da freqüência, sendo por isto denominados desvanecimentos seletivos, e são a principal causa de degradação do desempenho de enlaces rádio digitais de alta capacidade. Os modelos existentes para a caracterização estatística do desvanecimento por multipercurso são semi-empíricos e baseados em dados experimentais obtidos em regiões de clima temperado, acarretando uma má estimativa quando aplicados a regiões de clima tropical e equatorial. Neste trabalho é apresentada uma avaliação dos métodos existentes para previsão do desempenho de enlaces rádio digitais de alta capacidade, a partir da utilização de dados reais de desempenho extraídos de medidas em um tronco rádio de alta capacidade numa região tropical. / [en] The variations which happen in the troposphere layers throughout the time in relation to the median condition of the signal cause various phenomena that change the received signal level at digital radio relay systems randomly. The random changes are named fading. Fading is normally classified as fast or slow. The former is normally associated with the atmospheric multipath propagation and is strongly dependent on frequency; therefore, this is named selective fading and it is normally the cause of performance degradation in high capacity digital radio relays. The existing models for statistics of multipath fading are semi - empirical and based on experimental data extracts from regions the climate of which is temperate; and this gives a rough estimate with respect to the tropical and equatorial zones. This work presents an evaluation of existing methods of performance prediction for high capacity digital radio relay systems using real performance data obtained from measures of a high capacity digital radio link in operation in the tropical region.

Esta dissertação apresenta o desempenho da camada física de um sistema de comunicação sem fio baseado no padrão IEEE 802.16-2004 (WiMAX-fixo), em diferentes configurações e condições de operação. Para este propósito, foi elaborado um simulador da camada física WirelessMAN-OFDM implementado com o uso do aplicativo MATLAB® (versão R2008b) e de sua extensão SIMULINK®. Foram modeladas sete formas distintas para o canal de propagação, associando três tipos básicos de canal (sem desvanecimento, com desvanecimento seletivo e não seletivo em freqüência), duas configurações de mobilidade (sem mobilidade e mobilidade parcial) e duas condições para o ambiente de propagação (externo e interno). A propagação com desvanecimentos causados por multi-percursos empregou as especificações do ITU (International Telecommunications Union), fornecendo uma representação satisfatória de ambientes urbanos macro-celulares e possibilitando a comparação com outros sistemas de comunicação sem fio. Por meio da análise comparativa da taxa de erro de bit e da taxa de transferência efetiva de dados, estudou-se o desempenho dos esquemas de codificação e modulação especificados e a ação do controle adaptativo. O comportamento do WiMAX-fixo quando sujeito a perdas de propagação por multi-percursos e a condições de utilização caracterizadas por aplicações fixas e, adicionalmente, para aplicações parcialmente móveis, foi também avaliado. Assim, essa pesquisa permitiu uma visão complementar do padrão o que possibilitou a determinação de valores customizados para os níveis de SNR empregados no controle adaptativo, além da determinação das capacidades obteníveis nas condições de mobilidade parcial. / This thesis presents the physical layer performance of a wireless communications system based on the IEEE 802.16-2004 standard (fixed-WiMAX), in different configurations and operation conditions. For this purpose, a simulator of WirelessMAN-OFDM physical layer was designed and implemented using MATLAB® application (version R2008b) and its extension SIMULINK®. Seven different profiles for the propagation channel have been modeled, involving three basic types of channel (without fading, frequency-flat fading and frequency selective-fading), two mobility settings (without mobility and partial mobility) and two propagation environment conditions (outdoor and indoor). ITU (International Telecommunications Union) specifications were used for multipath fading propagation, providing a satisfactory representation of urban macro-cellular environments and allowing comparison with other wireless communication systems. Through comparative analysis of bit error rate and throughput, the performance of the specified modulation and coding schemes and the action of adaptive control were evaluated. The behavior of the fixed-WiMAX when subjected to a propagation environment with multipath fading and utilization conditions characterized by stationary applications and by partially mobile applications was also exploited. This research allowed a complementary vision of the standard which enabled the determination of customized values for the SNR levels employed in adaptive control, and furthermore the determination of the obtainable capacity under conditions of partial mobility.

Este trabalho concentra-se no aumento da robustez à taxa de erros em redes de sensores sem fio industriais (RSSFI). Para alcançar tal objetivo, é preciso, de algum modo, contornar os problemas intrínsecos da comunicação sem fio, que são, o ruído ambiental, interferências e desvanecimento por multipercurso. O multipercurso pode ser considerado um dos principais fatores que tornam as comunicações nas redes de sensores sem fio (RSSF) um verdadeiro desafio quando comparadas com outros meios, como a transmissão em fibra óptica, cabo ou mesmo transmissões de rádio ponto-a-ponto. Nesse sentido, propõe-se a diversidade de antenas como uma solução para minimizar os efeitos do multicaminho, com o objetivo de melhorar a confiabilidade do enlace de rádio para permitir o emprego de RSSF densas. O potencial da diversidade de antenas em RSSF não está totalmente explorado em aplicações industriais. Esta dissertação apresenta ainda, a técnica “Combinação de seleção” para RSSFI através de um algoritmo que seleciona a porta do receptor que apresenta o melhor indicador de qualidade de enlace e realiza a comutação das antenas nos módulos de rádio. Os resultados são analisados para dois tipos de enlaces, isto é, com e sem diversidade de antenas na recepção, e discute-se opções para melhorar o PER (“Packet Error Rate”) com as atuais técnicas de diversidade. / This work concentrates on the increase of reliability and robustness in Industrial Wireless Sensor Networks (IWSNs), decreasing the Packet Error Rate (PER). To achieve this objective, is need to somehow circumvent and reduce the underlying problems of wireless communication, which are: environmental noise, interference, and multipath fading. The multipath can be seen as the main factor which becomes the communications in the Wireless Sensor Networks (WSNs) a real challenge when compared to other types of means such as a transmission in fiber, cable or even point-to-point radio transmissions. In this sense, it is proposed antenna diversity as solution to reduce these effects, with the aim to improve the reliability of the radio link to allow the use of dense WSNs. The potential of antenna diversity in WSN is not fully exploited in industrial applications. In this sense, this dissertation presents the "Combination of selection" technique for IWSNs through an internal algorithm that selects the receiver port that has the highest LQI ("Link Quality Indicator") and performs an antenna switching in the radio modules. Also, options to improve PER using diversity techniques are discussed.

Made available in DSpace on 2016-04-04T18:31:22Z (GMT). No. of bitstreams: 1 Gildevane Aparecido Ferreira.pdf: 3776872 bytes, checksum: 2024d74a9d885d3bc67ca267094d9d6c (MD5) Previous issue date: 2008-02-25 / This MSc. thesis presents new results of activities with the development and characterization on RF devices operating on the 2,4 GHz channel, which has been done using a flat fast fading emulator. This RF emulator has been developed with the use of electronic circuits between them, and the presence of an attenuator which can be controlled by software and another one controlled by a power supply. The performance and characterization of the emulator has been done with some tests of video streaming links. The essential purpose is to present a simple and efficient approach to implement a testbed emulation of flat fast fading that can allow the RF signal to be confined inside a coaxial cable, where there is a controlled ambient whose permits to investigate the performance over all wireless networks. We perform also in this work some comparison to evaluate the behavior of both the 802.11b and 802.11g standards in flat fast fading channel through a video transmission and a further analysis of the jitter in many different power levels of the signal by assuming that the emulator has a perfect control of the system. / An?lise comparativa do desempenho das redes locais sem fio (WLANs), padr?o IEEE 802.11b e 802.11g, na transmiss?o de fluxo cont?nuo de v?deo, tamb?m conhecido como streaming de v?deo, simulando caracter?sticas de uma transmiss?o de v?deo em formato IPTV, com o intuito de identificar qual dos dois padr?es tem melhor desempenho na transmiss?o desse tipo de tr?fego. Esse trabalho foi motivado pela necessidade de implanta??o da segunda fase do projeto Exibe da TV PUC Campinas, que prev? a distribui??o da programa??o do canal universit?rio, em formato IPTV, atrav?s de redes IP sem fio. Para simula??o desse sistema de distribui??o de v?deo, foram feitas an?lises das caracter?sticas de distribui??o, transmiss?o e formatos do v?deo transmitido. As transmiss?es foram realizadas com o uso de um emulador de R?dio Freq??ncia que disp?e de dois atenuadores, um controlado por software e outro por uma fonte de tens?o. O emulador pode proporcionar um ambiente controlado, onde todas as transmiss?es puderam ser realizadas utilizando os dois padr?es de rede, garantindo uma correta identifica??o do canal, controle das atenua??es e acompanhamento dos fen?menos de propaga??o.

Made available in DSpace on 2016-04-29T13:18:12Z (GMT). No. of bitstreams: 1 Diana Alvim Pena Canavarros.pdf: 510987 bytes, checksum: c4c68992eb0813d2f9d82230c43c1bca (MD5) Previous issue date: 2009-05-14 / This study was carried out in order to analyze the behavior of self-control in children, comparing two types of procedure of gradual change: the procedure of gradual increase in the period of delay of greater reinforcement magnitude (fading in) and the procedure to decrease progressive period of delay in the reinforcement of smaller magnitude (fading out); for that, were analyzed competing schemes linked with components programmed for different magnitudes and delays of reinforcement. Ten children aged between seven and twelve years old participated in the study which involved activities on a computer with a program specially developed for this research. In the first link of the competitor chained scheme, a response in the selected component, producing, on a variable interval of 10 seconds, the second link in the chain, which consisted of a fixed time (the period of delay of reinforcement), in which the computer screen remained dark. The period of delay of reinforcement varied as the experimental condition programmed, from 1 second to 150 seconds. The third link in the chain was started with the appearance of a red square, and a response of clicking with the mouse produced the release of dots. All ten subjects participated in two initial conditions for the evaluation of sensitivity to differences in magnitude and delay of reinforcement. There were two different conditions of variation in the period of delay of reinforcement. Four participants were exposed to a condition in which the delays of the greater magnitude of reinforcement (3 points) were gradually increased (1s, 30s, 75s, 120s, 150s), while the component of lesser magnitude of reinforcement (1 point) remained constant, without variation (1s). Six participants were exposed to a condition in which the delays of the lower magnitude of reinforcement (1 point) were gradually decreased (150s, 120s, 75s, 30s, 1s, to four participants, 120s, 75s, 30s, 1s, for one participant, and 90s, 75s, 30s, 1s, for one participant), while the most important component of the increase (3 points) remained constant with the initial value of the sequence of delay indicated (150s, 120s and 90s, respectively). All ten participants showed differences in sensitivity in terms os difference of magnitude of delay of reinforcement, the two conditions of assessment, with some differences in the number of sessions per participant. In relation to the gradual increase of the delay of the greatest magnitude of reinforcement, the results show that most participants preferred for the component of impulsivity. In the condition of progressive reduction of the delay of the smaller magnitude of reinforcement, all six participants showed preference for the component of self-control. Only when the delay of the component of smaller magnitude of reinforcement decreased to 1 second, the majority of participants chose the component of impulsivity. It was found that the determinant factor is not the delay time itself, but the relative difference of values of delay between the two components / O presente estudo foi realizado com o objetivo de analisar o comportamento de autocontrole em crianças, a partir da comparação entre dois procedimentos de mudança gradual: o procedimento de aumento progressivo no período de atraso do reforço de maior magnitude (fading in) e o procedimento de diminuição progressiva no período de atraso do reforço de menor magnitude (fading out); para tanto foram analisadas escolhas em esquemas concorrentes encadeados, com componentes programados para diferentes magnitudes e atrasos do reforço. Dez crianças com idades entre sete e doze anos participaram do estudo que envolveu a realização de atividades em um computador, a partir de um programa especialmente desenvolvido para esta pesquisa. No primeiro elo do esquema concorrente encadeado, uma resposta no componente selecionado, produzia, em intervalo variável de 10 segundos, o segundo elo da cadeia, que consistia em um tempo fixo (o período de atraso do reforço), em que a tela do computador permanecia escura. O período de atraso do reforço variava, conforme a condição experimental programada, de 1 segundo a 150 segundos. O terceiro elo da cadeia era iniciado com o aparecimento de um quadrado vermelho e uma resposta de clicar com o mouse nesse quadrado produzia a liberação de pontos. Todos os dez participantes foram submetidos a duas condições iniciais de avaliação da sensibilidade a diferenças de magnitude e atraso do reforço. Houve duas condições diferentes de variação no período de atraso do reforço. Quatro participantes foram expostos a uma condição em que os atrasos do componente de maior magnitude do reforço (3 pontos) foram aumentados progressivamente (1s; 30s; 75s; 120s; 150s), enquanto que o componente de menor magnitude do reforço (1 ponto) permaneceu constante, sem variação (1s). Seis participantes foram expostos a uma condição em que os atrasos do componente de menor magnitude do reforço (1 ponto) foram diminuídos progressivamente (150s; 120s; 75s; 30s; 1s, para quatro participantes; 120s, 75s; 30s; 1s, para um participante, e 90s; 75s; 30s; 1s, para um participante); enquanto que o componente de maior magnitude do reforço (3 pontos) permaneceu constante com o valor inicial da sequência de atraso indicada (150s, 120s e 90s, respectivamente). Todos os dez participantes apresentaram sensibilidade as diferenças de magnitude e de atraso do reforço, nas duas condições de avaliação, com algumas diferenças no número de sessões realizadas por participante. Em relação à condição de aumento gradual do atraso do componente de maior magnitude do reforço, os resultados demonstram que a maioria dos participantes apresentou preferência pelo componente de impulsividade. Na condição de diminuição progressiva do atraso do componente de menor magnitude do reforço, todos os seis participantes, apresentaram preferência pelo componente de autocontrole. Somente quando, o atraso do componente de menor magnitude do reforço diminuiu para 1 segundo, a maioria dos participantes escolheu o componente de impulsividade

Esta dissertação apresenta o desempenho da camada física de um sistema de comunicação sem fio baseado no padrão IEEE 802.16-2004 (WiMAX-fixo), em diferentes configurações e condições de operação. Para este propósito, foi elaborado um simulador da camada física WirelessMAN-OFDM implementado com o uso do aplicativo MATLAB® (versão R2008b) e de sua extensão SIMULINK®. Foram modeladas sete formas distintas para o canal de propagação, associando três tipos básicos de canal (sem desvanecimento, com desvanecimento seletivo e não seletivo em freqüência), duas configurações de mobilidade (sem mobilidade e mobilidade parcial) e duas condições para o ambiente de propagação (externo e interno). A propagação com desvanecimentos causados por multi-percursos empregou as especificações do ITU (International Telecommunications Union), fornecendo uma representação satisfatória de ambientes urbanos macro-celulares e possibilitando a comparação com outros sistemas de comunicação sem fio. Por meio da análise comparativa da taxa de erro de bit e da taxa de transferência efetiva de dados, estudou-se o desempenho dos esquemas de codificação e modulação especificados e a ação do controle adaptativo. O comportamento do WiMAX-fixo quando sujeito a perdas de propagação por multi-percursos e a condições de utilização caracterizadas por aplicações fixas e, adicionalmente, para aplicações parcialmente móveis, foi também avaliado. Assim, essa pesquisa permitiu uma visão complementar do padrão o que possibilitou a determinação de valores customizados para os níveis de SNR empregados no controle adaptativo, além da determinação das capacidades obteníveis nas condições de mobilidade parcial. / This thesis presents the physical layer performance of a wireless communications system based on the IEEE 802.16-2004 standard (fixed-WiMAX), in different configurations and operation conditions. For this purpose, a simulator of WirelessMAN-OFDM physical layer was designed and implemented using MATLAB® application (version R2008b) and its extension SIMULINK®. Seven different profiles for the propagation channel have been modeled, involving three basic types of channel (without fading, frequency-flat fading and frequency selective-fading), two mobility settings (without mobility and partial mobility) and two propagation environment conditions (outdoor and indoor). ITU (International Telecommunications Union) specifications were used for multipath fading propagation, providing a satisfactory representation of urban macro-cellular environments and allowing comparison with other wireless communication systems. Through comparative analysis of bit error rate and throughput, the performance of the specified modulation and coding schemes and the action of adaptive control were evaluated. The behavior of the fixed-WiMAX when subjected to a propagation environment with multipath fading and utilization conditions characterized by stationary applications and by partially mobile applications was also exploited. This research allowed a complementary vision of the standard which enabled the determination of customized values for the SNR levels employed in adaptive control, and furthermore the determination of the obtainable capacity under conditions of partial mobility.