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In Code Division Multiple Access (CDMA) systems forward error correction (FEC) is an important factor in improving system performance. Because of the multiple access interference observed in asynchronous CDMA, FEC is required to improve system capacity. Several alternative coding techniques are available, including "trellis codes" specifically designed for CDMA, very low rate convolutional codes and conventional convolutional codes. An analytic approach is developed to compare the performance of different coding techniques for CDMA on the same basis by extending several improved analysis techniques which were developed for uncoded CDMA. Analytic results are presented for additive white Gaussian noise (AWGN) channels and frequency non-selective Rician Fading (FNRF) channels. The performance of coded CDMA systems in frequency selective Rayleigh fading channels is also analyzed using simulation techniques. Both analytic and simulation results show that by using trellis codes or very low rate convolutional codes significant performance improvement is achieved over conventional convolutional codes. Trellis codes outperform very low rate convolutional codes in AWGN and FNRF channels while both codes show similar performance in frequency selective Rayleigh fading channels. / Master of Science

Since the 1950s, hidden Markov models (HMMS) have seen widespread use in electrical engineering. Foremost has been their use in speech processing, pattern recognition, artificial intelligence, queuing theory, and communications theory. However, recent years have witnessed a renaissance in the application of HMMs to the analysis and simulation of digital communication systems. Typical applications have included signal estimation, frequency tracking, equalization, burst error characterization, and transmit power control. Of special significance to this thesis, however, has been the use of HMMs to model fading channels typical of wireless communications. This variegated use of HMMs is fueled by their ability to model time-varying systems with memory, their ability to yield closed form solutions to otherwise intractable analytic problems, and their ability to help facilitate simple hardware and/or software based implementations of simulation test-beds. The aim of this thesis is to employ and exploit hidden Markov fading models within an iterative (turbo) decoding framework. Of particular importance is the problem of channel estimation, which is vital for realizing the large coding gains inherent in turbo coded schemes. This thesis shows that a Markov fading channel (MFC) can be conceptualized as a trellis, and that the transmission of a sequence over a MFC can be viewed as a trellis encoding process much like convolutional encoding. The thesis demonstrates that either maximum likelihood sequence estimation (MLSE) algorithms or maximum <I> a posteriori</I> (MAP) algorithms operating over the trellis defined by the MFC can be used for channel estimation. Furthermore, the thesis illustrates sequential and decision-directed techniques for using the aforementioned trellis based channel estimators <I>en masse</I> with an iterative decoder. / Master of Science

Made available in DSpace on 2016-12-08T16:44:35Z (GMT). No. of bitstreams: 1 PGPV10MA050.pdf: 404855 bytes, checksum: 36e6d7d5b5fb8a59d940f37f3e2de324 (MD5) Previous issue date: 2010-02-25 / Rootstocks are used primarily for pest resistance, they are a link between the soil and the scion, play an important role in vine adaption to environmental factors. Rootstocks and training systems can influence the productivity, fruit and wine composition. The objective of this study was evaluate the influence of three rootstocks and two training systems on vineyard productivity, scion growth, physical-chemical quality of fruits and wine chemical composition of Cabernet Sauvignon grapevine produced in high altitude regions of Santa Catarina State. The study was conducted in a experimental vineyard located at the city of Painel (28°01&#8223;02 S and 50°08&#8223;57 W, altitude 1200 m). The cultivar evaluated was Cabernet Sauvingon grafted on Paulsen 1103 (V. berlandieri x V. rupestris), Couderc 3309 and 101-14 Mgt (V. riparia x V. rupestris), the training systems evaluated were vertical shoot positioning trellis and Y trellis. The plants were five years old and the spacing was 3,0 x 1,5 m. The experiment was evaluated at the seasons 2007/08 and 2008/09. According to the results, plants grafted on 1103P and trained in vertical shoot positioning trellis have lowest yields, 3309C is the rootstock less vigorous and and acts positively on fruit set. The high productivity of Y trellis reflect negatively increasing grape acidity. The rootstocks 1103 P and 101-14 Mgt, presents the best results for grape anthocyanins contents. The wine color is not affected by the rootstocks and the training systems. Wine made with grapes from plants grafted on 1103P and trained in Y trellis have higher rates of total polyphenols index and tannins than wines made from grapes of plants trained in vertical shoot positioning trellis and grafted on 1103P. / Os porta-enxertos são usados primariamente como uma forma de resistência a pragas e doenças, eles são uma ligação entre o solo e a copa e desempenham um papel importante na adaptação da videira a fatores ambientais. Os porta-enxertos e os sistemas de condução podem influenciar na produtividade, na composição da fruta e do vinho. O objetivo deste trabalho foi avaliar a influência de três porta-enxertos e dois sistemas de condução na produtividade do vinhedo, no crescimento da copa, na qualidade físico-química dos frutos e na composição química do vinho elaborado com a uva Cabernet Sauvignon, produzida nas regiões de altitude, do estado de Santa Catarina. O experimento foi conduzido em um vinhedo experimental da Epagri - Estação Experimental de São Joaquim, localizada no município de Painel (28°01&#8223;02 S e 50°08&#8223;57 O, altitude 1.200m). O trabalho foi executado com a variedade Cabernet Sauvignon, enxertado sobre Paulsen 1103 (Vitis berlandieri x Vitis rupestris), Couderc 3309 (Vitis riparia x Vitis rupestris) e 101-14 Mgt (Vitis riparia x Vitis rupestris), em dois sistemas de condução, espaldeira e manjedoura, com cinco anos de plantio, no espaçamento de 3,0 x 1,5 m. O experimento foi avaliado nas safras 2007/08 e 2008/09. De acordo com os resultados obtidos conclui-se que plantas enxertadas em 1103P e conduzidas em espaldeira apresentam as menores produtividades, 3309C é o porta-enxerto menos vigoroso e atua de forma positiva na frutificação efetiva. A produtividade elevada do sistema manjedoura reflete de forma negativa no aumento da acidez da uva. Os porta-enxertos 1103 P e 101-14 Mgt, apresentam os melhores resultados para antocianinas das uvas. A cor dos vinhos não é afetada pelos porta-enxertos e pelos sistemas de condução. Vinhos elaborados com frutos de plantas enxertadas em 1103P e conduzidas em manjedoura apresentaram maiores índices de polifenóis totais e taninos do que os vinhos originados de uvas de plantas conduzidas em espaldeira e enxertadas em 1103P