The performance of a mobile satellite communications link can be determined by the propagation path between a satellite and mobile users. Some of the most important factors are multipath propagation and vegetative shadowing. System designers should have the most reliable information about the statistics of fade duration in order to determine fade margin or to compensate for the fades using modulation and coding scheme. This report describes a simulator, PROSIM, developed at Virginia Tech for simulating a propagation model in land mobile satellite communications. The simulator is based on a random number generator that generates data sets to compute statistics of the propagation channel. Performance of the simulator was evaluated by comparing statistics from an analytical model and experimental data provided by W. Vogel of Univ. of Texas at Austin and J. Goldhirsh of the Applied Physics Laboratory. New expressions for phasor plot and its mathematical expression for lognormal channel were derived and were simulated. Finally, the advantages of the simulator using random number generator in simulating the propagation model are described. / Master of Science

Orientador: Michel Daoud Yacoub / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-07T23:52:12Z (GMT). No. of bitstreams: 1 SantosFilho_JoseCandidoSilveira_D.pdf: 1465914 bytes, checksum: 30b3ae8d49f9e0566332c17202cc27cb (MD5) Previous issue date: 2006 / Resumo: Este trabalho provê as seguintes contribuições ao estudo de canais de desvanecimento: (i) aproximações em forma fechada para a função densidade de probabilidade e a função distribuição acumulada de somas de envoltórias independentes sob desvanecimento Nakagami, Rice, Hoyt, Weibull ou lognormal; (ii) expressões gerais para a taxa e duração médias de desvanecimento do combinador de diversidade por seleção pura em canais de desvanecimento arbitrários; (iii) expressões gerais para a taxa e duração médias de desvanecimento dos combinadores de diversidade por seleção pura, ganho igual e razão máxima em canais Ricianos correlacionados e (iv) simulador de envoltória para canais de desvanecimento Nakagami, aplicável a valores arbitrários do parâmetro de desvanecimento e cenários anisotrópicos de propagação / Abstract: This work provides the following contributions to the study of fading channels: (i) closed-form approximations to the probability density function and the cumulative distribution function of sums of independent envelopes under Nakagami, Rice, Hoyt, Weibull, or lognormal fading; (ii) general expressions for the average fade rate and the average fade duration of pure selection combining over arbitrary fading channels; (iii) general expressions for the average fade rate and the average fade duration of pure selection, equal-gain, and maximal-ratio combining over correlated Ricean channels, and (iv) envelope simulator for Nakagami fading channels, applicable to arbitrary values of fading parameter and nonisotropic propagation scenarios / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

The performance of a mobile satellite communications link is conditioned by the characteristics of the propagation path between a satellite and mobile users. The most important propagation effect in land mobile satellite system is roadside attenuation of the signals due to vegetation or urban structures. System designers should have the most reliable information about the statistics of the propagation channel to build reliable systems that can compensate for bad propagation conditions. In 1998, the Virginia Tech Antenna Group developed a simulator, PROSIM, to simulate a propagation channel in the case of roadside tree attenuation in land mobile satellite systems. This thesis describes some improvements to PROSIM, and the adaptation and validation of PROSIM for Digital Audio Radio Satellite systems operating at S-band frequencies. The performance of the simulator for S-band frequencies was evaluated through a measurement campaign conducted with the XM Radio signals at 2.33 GHz in various propagation environments. Finally, additional results on dual satellite systems and fade correlation are described. / Master of Science

Orientador: Michel Daoud Yacoub / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T06:51:34Z (GMT). No. of bitstreams: 1 Costa_DanielBenevidesda_M.pdf: 1293492 bytes, checksum: 3aa8e540fd57db56b2ee4469c60307be (MD5) Previous issue date: 2006 / Resumo: Esta dissertação provê uma análise das estatísticas de ordem superior para canais de desvanecimento WeibuII e Nakagami-m. Considerando canais de desvanecimento WeibulI, devido à ausência de um modelo físico para tais canais, estatísticas conjuntas de duas variáveis WeibuII correlacionadas foram obtidas em forma fechada e em função de parâmetros físicos bem conhecidos. Outra estatística encontrada foi a taxa de cruzamento de nível e a duração média de desvanecimento usando diversidade com dois ramos para canais WeibuII correlacionados, desbalanceados e não-idênticos. Além disso, uma caracterização do comportamento do processo de fase e de sua derivada temporal para sinais WeibuII foi realizada. Analisando canais de desvanecimento Nakagami-m, uma expressão simples e em forma fechada para a taxa de cruzamento de fase generalizada foi obtida. Resultados de simulação completamente validaram a formulação proposta. Além disso, novas estatísticas em forma fechada para a envoltória, para as componentes em fase e em quadratura, para a fase e para suas respectivas derivadas temporais foram obtidas / Abstract: This dissertation provides an analysis of the higher order statistics for WeibuII and Nakagami-m fading channels. Conceming WeibuII fading channels, due to the absence of a fading model related of such channels, joint statistics for two correlated WeibuII variates were obtained in cIosed-form and in terms of welI-known physical parameters. Other statistics found were the levei crossing rate and the average fade duration for unbalanced, non-identical, correlated WeibuII channels operating over two branches of diversity. Furthermore, a characterization of the behaviour of the phase process and its time derivative for WeibuII signals was accomplish. Conceming Nakagami-m fading channeIs, a simple and cIosed-form expression for the generalized phase crossing rate was obtained. Results of simulation thoroughly validated the formulation proposed. Moreover, new cIosed-form statistics for the envelope, for the in-phase and quadrature components, for the phase and its respective time derivative were derived. / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica