In this thesis, we propose a novel architecture for hybrid radio frequency (RF)/free–space optics (FSO) wireless systems. Hybrid RF/FSO systems are attractive since the RF and FSO sub–systems are affected differently by weather and fading phenomena. We give a thorough introduction to the RF and FSO technology, respectively. The state of the art of hybrid RF/FSO systems is reviewed. We show that a hybrid system robust to different weather conditions is obtained by joint bit–interleaved coded modulation (BICM) of the bit streams transmitted over the RF and FSO sub–channels. An asymptotic performance analysis reveals that a properly designed convolutional code can exploit the diversity offered by the independent sub–channels. Furthermore, we develop code design and power assignment criteria and provide an efficient code search procedure. The cut–off rate of the proposed hybrid system is also derived and compared to that of hybrid systems with perfect channel state information at the transmitter. Simulation results show that hybrid RF/FSO systems with BICM outperform previously proposed hybrid systems employing a simple repetition code and selection diversity.

In this thesis, we propose a novel architecture for hybrid radio frequency (RF)/free–space optics (FSO) wireless systems. Hybrid RF/FSO systems are attractive since the RF and FSO sub–systems are affected differently by weather and fading phenomena. We give a thorough introduction to the RF and FSO technology, respectively. The state of the art of hybrid RF/FSO systems is reviewed. We show that a hybrid system robust to different weather conditions is obtained by joint bit–interleaved coded modulation (BICM) of the bit streams transmitted over the RF and FSO sub–channels. An asymptotic performance analysis reveals that a properly designed convolutional code can exploit the diversity offered by the independent sub–channels. Furthermore, we develop code design and power assignment criteria and provide an efficient code search procedure. The cut–off rate of the proposed hybrid system is also derived and compared to that of hybrid systems with perfect channel state information at the transmitter. Simulation results show that hybrid RF/FSO systems with BICM outperform previously proposed hybrid systems employing a simple repetition code and selection diversity.

Orientador: Michel Daoud Yacoub / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-07T11:29:09Z (GMT). No. of bitstreams: 1 Mendes_JoseRicardo_M.pdf: 915286 bytes, checksum: e4cfda5648e3725df9db2ff028e5c811 (MD5) Previous issue date: 2006 / Resumo: Esta dissertação deduz e analisa coeficientes de correlação de sinais em diversos canais com desvanecimento, bem como especifica os respectivos parâmetros de coerência - distância de coerência, tempo de coerência e largura de banda de coerência. Tais parâmetros são extraídos do coeficiente de correlação da envoltória, estatística fornecida aqui apenas para canais com desvanecimento Rice, devido à complexidade de seu cálculo. Para modelos mais abrangentes de canais com desvanecimento, provê-se o coeficiente de correlação da potência, aproximação simples e geralmente acurada daquele coeficiente. Por fim, através de resultados numéricos, discriminam-se fatores que atuam sobre os parâmetros de coerência: ondas dominantes influem fundamentalmente na distância de coerência e no tempo de coerência; desequilíbrios de potência média dos componentes aleatórios em quadratura, primordialmente na largura de banda de coerência; anisotropia do espalhamento das ondas difusas e diretividade das antenas receptoras, somente na distância de coerência e no tempo de coerência; e a não-estacionariedade do ambiente, em todos os parâmetros de coerência / Abstract: This dissertation derives and examines correlation coefficients of signals in many fading channels, as well as specifies the respective coherence parameters - coherence distance, coherence time, and coherence bandwidth. Such parameters are extracted from the envelope correlation coefficient, statistic calculated here only for Ricean fading channels, owing to the complexity of its deduction. For more comprehensive models of fading channels, it is provided the power correlation coefficient, simple and usually accurate approximation of that coefficient. Finally, by means of numerical results, factors that affect the coherence parameters are enumerated: dominant waves influence fundamentally on the coherence distance and on the coherence time; mean power inequalities between the quadrature random components, mainly on the coherence bandwidth; anisotropy of the diffuse waves spreading, only on the coherence distance and on the coherence time; and nonstationarity of the environment, on all coherence parameters / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

In this thesis, we propose a novel architecture for hybrid radio frequency (RF)/free–space optics (FSO) wireless systems. Hybrid RF/FSO systems are attractive since the RF and FSO sub–systems are affected differently by weather and fading phenomena. We give a thorough introduction to the RF and FSO technology, respectively. The state of the art of hybrid RF/FSO systems is reviewed. We show that a hybrid system robust to different weather conditions is obtained by joint bit–interleaved coded modulation (BICM) of the bit streams transmitted over the RF and FSO sub–channels. An asymptotic performance analysis reveals that a properly designed convolutional code can exploit the diversity offered by the independent sub–channels. Furthermore, we develop code design and power assignment criteria and provide an efficient code search procedure. The cut–off rate of the proposed hybrid system is also derived and compared to that of hybrid systems with perfect channel state information at the transmitter. Simulation results show that hybrid RF/FSO systems with BICM outperform previously proposed hybrid systems employing a simple repetition code and selection diversity. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate