Rayleigh Channel
Mostrando 13-24 de 25 artigos, teses e dissertações.
-
13. RAY TRACING ANALYSIS OF THE EFFECTS OF PROPAGATION ON MULTIPLE-INPUT MULTIPLE-OUTPUT (MIMO) CHANNELS / ANÁLISE DOS EFEITOS DA PROPAGAÇÃO EM CANAIS COM MÚLTIPLAS ENTRADAS E MÚLTIPLAS SAÍDAS (MIMO) COM BASE NO TRAÇADO DE RAIOS
A ray tracing model based on the method of images has been applied to study the propagation of radio waves in the regions of Copacabana and Ipanema in Rio de Janeiro. In such highly urbanized environments, it can be realistically assumed that propagation is restricted to a horizontal section of the street canyons characterized by the blocks of buildings. Sev
Publicado em: 2005
-
14. Computational modelling of mobile communication channels. / Modelagem computacional de canais de comunicação móvel.
A modelagem computacional tem se tornado uma poderosa ferramenta utilizada mundialmente em pesquisas sobre sistemas de comunicação móvel. Em tais sistemas, a modelagem do canal é fator indispensável, pois as características de mobilidade e propagação presentes nesse tipo de sistema são responsáveis por distorções ocorridas sobre o sinal transmiti
Publicado em: 2004
-
15. Códigos de Bloco com Decodificação Turbo Adaptados às Especificações do Padrão DVB-RCT / Códigos de Bloco com Decodificação Turbo Adaptados às Especificações do Padrão DVB-RCT
Product codes formed by serial concatenation of single parity check component codes are used in this thesis to fulfill the requirements of coding rate and block length expressed by the standard known as DVB-RCT (Digital Video Broadcasting - Return Channel Terrestrial). This standard describes the parameters of the physical layer for a digital TV wireless ret
Publicado em: 2004
-
16. Markovian models and performance analysis of ARQ schemes on mobile channels / Modelos markovianos e anÃlise de desempenho de esquemas ARQ em canais mÃveis
O presente trabalho desenvolve modelos de canais de estados finitos (CEF) para um sistema de comunicaÃÃo discreto, composto por um modulador digital, um canal com desvanecimento plano (Rayleigh ou Rice) correlacionado no tempo e um demodulador, bem como estuda as propriedades de correlaÃÃo do processo de desvanecimento para analisar o desempenho de proto
Publicado em: 2004
-
17. Avaliação de Técnicas para Transmissão Digital em Canal com Desvanecimento Lento e Não seletivo em Freqüência Modelado com a Distribuição n-
In this dissertation, a theoretical and mathematical study about fading channels modeled according to the n- distribution is presented. The n- distribution includes the Hoyt and the Nakagami-m distributions as special cases, and therefore, the One-Sided Gaussian and the Rayleigh distributions also constitute special cases. This dissertation presents the eval
Publicado em: 2003
-
18. On Higher Order Statistics of the k-u Distribution / Estatísticas de Ordem Superior para a Distribuição k-u
A theoretical study about fading channels modeled according to the k-u distribution is developed to obtain the higher order statistics. The k-u density function is a general fading distribution used to model the wave propagation in a non homogeneous environment and includes the Rayleigh, Rice and Nakagami-m density functions as special cases. This dissertati
Publicado em: 2003
-
19. Analise de desempenho de detectores multiusuarios lineares em canal com desvanecimento rayleigh
In this work simplified expressions to evaluate the performance of multiuser MMSE detector in CDMA systems using random spreading sequence on multipath Rayleigh fading channel are obtained. This work also presents simplified expressions for the mean bit error probability for amultirate system using random spreading sequences on AWGN and multipath Rayleigh fa
Publicado em: 2002
-
20. Estudo da viabilidade da utilização de codigo de Reed Solomon na codificação de canal movel TDMA
This study aims to investigate the use of Reed-Solomon codes in the channel coding of the TDMA IS-136 system. Block codes seem to be more suitable to the time slot structure of the TDMA frame. Moreover, the choice of a Reed-Solomon code was based on the best capability and the minimization of the redundant bits introduced by the actual convolutional encoding
Publicado em: 2002
-
21. Analise de desempenho de sitemas CDMA utilizando arranjo de antenas em canais seletivos em frequencia
The aim of this work is to carry out a performance analysis of a single cell CDMA cellular system with a uniform linear antenna array at the base station for both downlink and uplink. This analysis is based on the evaluation of the average bit error probability. The system performance analysis is developed with binary shift keying (BPSK) modulated signals on
Publicado em: 2002
-
22. Convecção natural em uma cavidade aberta para um canal
In this work the problem of natural convection in a rectangular open cavity with and without the presence of a shrouding wall has been analysed. One vertical wall is heated and the horizontal walls are adiabatic. The other vertical wall is open to the ambient or a fluid reservoir. That is the opening. A shrouding wall is placed in front of this open wall for
Publicado em: 1999
-
23. Esquemas de codificação para um sistema DS-CDMA com portadoras ortogonais
In this dissertation, a study of an orthogonal multicarrier DS-CDMA multiple access system is presented lhe performance of the system in a multipath Rayleigh fading channel was analyzed through computer simulation. The performance gains through the use of channel state information in the system were obtained Two channel coding schemes for the studied system
Publicado em: 1998
-
24. Desempenho de codigos TCM sobre aneis em canais com desvanecimento
This thesis presents the performance of coded modulation with convolutional codes over rings of integers modulo-8 on fadinf channels. The performance is obtained by computer simulation and it is given by curves of Bit Error Rate (BER) versus Signal to Noise Ratio (SNR). Basic concepts related with codes modulation, characterization of digital modulations, co
Publicado em: 1998