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1
Geller, Joseph. "The manuscript version of the memoirs of Dov Ber Birkenthal (Ber of Bolochew)." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22375.
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This thesis is concerned with the manuscript of the memoirs of Dov Ber Birkenthal, Ber of Bolechow. The memoirs describe Jewish existence in eighteenth century Poland and provide valuable information regarding economic, social and cultural matters of that era. Uncovered in 1912, the manuscript was edited and published in Hebrew and translated into English by Dr. M. Vishnitzer.By primary supposition of the present thesis is that Dr. Vishnitzer's transcription of the manuscript is inaccurate, and for this reason, a re-working of the memoirs has been undertaken. In addition to providing an authentic transcription of the manuscript, this thesis also contains a description of Birkenthal's life, an analysis of the uniqueness of this somewhat exceptional person and an account of how the memoirs have been used in the literature. Moreover, the historical value of the memoirs has been assessed, and an indepth analysis of the flaws contained in Vishniter's transcription has been provided.
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Ortega, Blanco Rubén. "Análise de SNIR e BER para redes acústicas submarinas." reponame:Repositório Institucional da UnB, 2015. http://repositorio.unb.br/handle/10482/19534.
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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2015.Submitted by Albânia Cézar de Melo (albania@bce.unb.br) on 2016-02-16T14:01:50Z No. of bitstreams: 1 2015_RubenOrtegaBlanco.pdf: 78834010 bytes, checksum: 3420abfa3f7efe2d616b97f09d14ff70 (MD5)
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O objetivo do seguinte trabalho é determinar um modelo matemático que permita-nos obter a Relação Sinal Ruído mais Interferência (SNIR do Inglês Signal-to-Noise plus Interference Ratio), a Taxa de Erro de Bits (BER do Inglês Bit Error Rate) de um salto e a Taxa de Erro de Bits fim-a-fim numa rede acústica submarina. Com esse propósito foi desenvolvido um modelo matemático que permite o cálculo destes parâmetros considerando a interferência para o protocolo de acesso ao meio (MAC do Inglês Medium Access Control) ALOHA puro. Também foi necessário desenvolver antes diferentes parâmetros da rede, tais como, distância média do salto, distância média até o nó central, distância média entre os nós, número médio de saltos na rota e desvio médio. Com o uso deste modelo também é possível obter o valor da frequência ótima utilizando uma função de otimização. Comparações entre a Taxa de Erro de Bits de um salto e fim-a fim também forem feitas, para diferentes valores de máximo ângulo de desvio na topologia de rede usada. Estas comparações demonstran quando pode ser mais convenente o uso de um salto ou múltiple-salto. Simulações Monte-Carlo e modelo forem comparados com o propósito de validar os resultados obtidos. Estas comparações demostram a grande similitude entre nosso modelo e as simulações de Monte-Carlo. Além disso foi possível o estudo do comportamento da SNIR e do BER variando importante parâmetros da rede tais como frequência de transmissão, número de nós, raio da esfera e máximo ângulo de desvio. Os resultados obtidos provarem que a SNIR para um salto diminui com o aumento do número de nós e o raio da esfera, mas aumenta com o incremento da potência de transmissão. O comportamento de BER é contrário ao comportamento de SNIR. Também foi possível observar a existência da frequência ótima, onde os melhores valores de SNIR e o BER são obtidos. ______________________________________________________________________________________________ ABSTRACT
The objective of this work is to nd a mathematical model that allow us to obtain the Signal-to-Noise plus Interference Ratio (SNIR), the One-Hop Bit Error Rate (BER) and the End-to-End Bit Error Rate for an Underwater Acoustic Network (UAN). Considering this, it was developed a model that includes the interference as an important impairment and for ALOHA MAC (Medium Access Control) protocol. In addition, it was necessary to obtain before several parameters from the network, such as, average distance of the hop, average distance between nodes, average distance to the central node, average number of hops and average deviation. With this model, it is also possible to nd the optimal value of frequency using an optimization function. It was made comparisons between the One-Hop BER and the End-to-End BER for various values of maximal deviation angle. This comparison shows when it is more adequate to either use one-hop or multi-hop. Finally, we compared numerical and Monte-Carlo simulation results, giving a rst validation to our model. These comparisons show a big similitude between the developed model and the Monte-Carlo simulation. In addition, it was possible to analyse the behaviour of the SNIR and BER by varying important parameters of the network, such as, transmission frequency, number of nodes and sphere radius among others. From the obtained results it was prove that the SNIR decreases with an increase from the number of nodes and the sphere radius, but increases with the transmission power. The End-to-End BER has an contrary behavior with the SNIR.
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Roy, Tamoghna. "BER Modeling for Interference Canceling Adaptive NLMS Equalizer." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/78055.
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Adaptive LMS equalizers are widely used in digital communication systems for their simplicity in implementation. Conventional adaptive filtering theory suggests the upper bound of the performance of such equalizer is determined by the performance of a Wiener filter of the same structure. However, in the presence of a narrowband interferer the performance of the LMS equalizer is better than that of its Wiener counterpart. This phenomenon, termed a non-Wiener effect, has been observed before and substantial work has been done in explaining the underlying reasons. In this work, we focus on the Bit Error Rate (BER) performance of LMS equalizers.
At first a model – the Gaussian Mixture (GM) model – is presented to estimate the BER performance of a Wiener filter operating in an environment dominated by a narrowband interferer. Simulation results show that the model predicts BER accurately for a wide range of SNR, ISR, and equalizer length. Next, a model similar to GM termed the Gaussian Mixture using Steady State Weights (GMSSW) model is proposed to model the BER behavior of the adaptive NLMS equalizer. Simulation results show unsatisfactory performance of the model. A detailed discussion is presented that points out the limitations of the GMSSW model, thereby providing some insight into the non-Wiener behavior of (N)LMS equalizers. An improved model, the Gaussian with Mean Square Error (GMSE), is then proposed. Simulation results show that the GMSE model is able to model the non-Wiener characteristics of the NLMS equalizer when the normalized step size is between 0 and 0.4. A brief discussion is provided on why the model is inaccurate for larger step sizes.Master of Science
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Laster, Jeffery D. "Robust GMSK Demodulation Using Demodulator Diversity and BER Estimation." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30618.
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This research investigates robust demodulation of Gaussian Minimum Shift Keying (GMSK) signals, using demodulator diversity and real-time bit-error-rate (BER) estimation. GMSK is particularly important because of its use in promi- nent wireless standards around the world (GSM, DECT, CDPD, DCS1800, and PCS1900). The dissertation begins with a literature review of GMSK demodu- lation techniques (coherent and noncoherent) and includes an overview of single- channel interference rejection techniques in digital wireless communications. Vari- ous forms of GMSK demodulation are simulated, including the limiter discrimina- tor and di erential demodulator (i.e., twenty-five variations in all). Ten represent new structures and variations. The demodulator performances are evaluated in realistic wireless environments, such as additive white Gaussian noise, co-channel interference, and multipath environments modeled by COST207 and SMRCIM. Certain demodulators are superior to others for particular channel impairments, so that no demodulator is necessarily the best in every channel impairment.
This research formally introduces the concept of demodulator diversity, a new idea which consists of a bank of demodulators which simultaneously demodulate the same signal and take advantage of the redundancy in the similar signals. The dissertation also proposes practical real-time BER estimation techniques which have tremendous ramifications for communications. Using Parzen's estimator for probability density functions (pdfs) and Gram-Charlier series approximation for pdfs, BER can be estimated using short observation intervals (10 to 500 training symbols) and, in some cases, without any training sequence. We also introduce new variations of Gram-Charlier estimation using robust estimators. BER (in place of MSE) can now drive adaptive signal processing. Using a cost function and gradient for Parzen's estimator (derived in this paper), BER estimation is applied to demodulator diversity with substantial gains of 1-10 dB in carrier- to-interference ratio over individual receivers in realistic channels (with adaptive selection and weighting). With such gains, a BER-based demodulator diversity scheme can allow the employment of a frequency reuse factor of N = 4, instead of N = 7, with no degradation in performance. A lower reuse factor means more channels are available in a cell, thus increasing overall capacity. The resulting techniques are simple and easily implemented at the mobile. BER estimation techniques can also be used in BER-based equalization and dynamic allocation of resources.Ph. D.
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Montaldi, Ana Paula de Lima. "Avaliação da resposta celular mediada pelo quimioterápico temozolomida associada ao inibidor do reparo do DNA metoxiamina em linhagens de glioblastoma." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/17/17135/tde-02032010-154403/.
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Os gliomas compreendem mais de 70% de todos os tumores cerebrais primários. Mesmo com tratamento agressivo, a média de sobrevivência relatada para estes tumores é geralmente menor do que 1 ano após o diagnóstico. A quimioterapia baseada em agentes alquilantes, como a temozolomida (TMZ), tem mostrado, em média, uma modesta resposta e pequeno aumento da sobrevida. As principais lesões causadas pela TMZ são os aductos N7-metil-G e N3-metil-A, que são processados pelo reparo por excisão de base (BER), compreendendo mais de 80% das lesões induzidas no DNA pela TMZ. Há evidência de que a resistência a este quimioterápico pode ser causada em parte por um eficiente processo de reparo via BER, mas poucos estudos têm focalizado essa abordagem. Metoxiamina (MX) é um inibidor do reparo via BER que tem sido atualmente investigado como um possível aliado no combate a vários tipos de tumores, aumentando os efeitos citotóxicos de drogas, tais como a TMZ. No presente trabalho, foram avaliadas as respostas celulares de células de glioblastoma (GBM) ao tratamento com a TMZ, associada ou não à MX. Foram analisados parâmetros como citotoxicidade (24 h, Kit XTT), sobrevivência celular (120 h, Kit XTT) e clonogênica (10 dias após o tratamento), danos no DNA pelo Ensaio Cometa (2, 6, 12 e 24 h), a indução de apoptose (24, 48 e 72 h) e alterações na expressão gênica e transcricional (24, 48 e 72h) de genes envolvidos na via de reparo por BER. Sob tratamento das linhagens de GBM (U87, U343, U251, U138 e T98G) a diferentes concentrações de TMZ (100 a 1000 M), o efeito citotóxico foi observado em células analisadas após 120 h, sendo que a linhagem T98G foi a mais resistente ao tratamento com TMZ e foi a única a apresentar diferenças significativas entre o tratamento sozinho e combinado (p 0,05). Assim, foi selecionada a linhagem T98G para os demais experimentos e estudar as possíveis vias implicadas na resistência a essa droga. A sobrevivência clonogênica das células T98G foi reduzida, sob tratamento com a TMZ (100 a 800 M), com diferença significativas para as concentrações superiores a 400 M. Observou-se que o efeito da TMZ foi acentuado quando associada ao inibidor, com diferenças significativas para todas as concentrações testadas. A droga induziu uma maior porcentagem de danos no DNA (Ensaio Cometa) para ambos os tratamentos (400 e 600 M) e nos tempos de 2 e 6 h, com diferenças significativas entre os tratamentos (TMZ e TMZ+MX), somente na concentração de 600 M/2 h. Entretanto esses danos se equipararam nos tempos seguintes. A indução de apoptose analisada nas células T98G mostrou a freqüência máxima de 24,2% no tempo de 72h, na concentração de 600 M de TMZ, enquanto que uma maior indução de apoptose (47,7%) foi observada para a mesma concentração no tratamento combinado (TMZ + MX), resultando em diferenças significativas. A análise de expressão gênica realizada para os genes APE1, FEN1 e XRCC1, mostraram que houve uma menor indução dos genes APE1 e FEN1 no tratamento combinado. A expressão da proteína APE1 (analisada por Western blot) foi menos intensa em todos os tempos de tratamento combinado (TMZ + MX), possivelmente pelo bloqueio dos sítios AP causado pelo inibidor MX. A proteína FEN1 mostrou-se menos expressa na comparação dos tratamentos, nos tempos de 48 e 72 h, indicando uma inibição de proteínas da via BER downstream à remoção de sítios AP por APE1, possivelmente pela ligação de MX. PCNA teve sua expressão protéica aumentada no tratamento combinado, nos tempos de 24 h, e principalmente em 48 h, sugerindo uma indução devida a um aumento de danos no DNA. Portanto, os resultados dos ensaios realizados com a associação da TMZ à MX demonstraram a influência do tratamento combinado sobre a expressão de proteínas envolvidas no reparo via BER, o que contribuiu para uma redução da capacidade proliferativa das células T98G em decorrência da maior indução de danos por aductos DNA-MX não reparados, resultando também em aumento de morte celular apoptótica. Esses dados mostram que a modulação do reparo via BER pode constituir uma estratégia promissora para aumentar a eficácia do tratamento com a TMZ, o que poderá futuramente embasar a escolha de procedimentos terapêuticos que resultem numa maior eficácia do tratamento de gliomas com agentes alquilantes.Gliomas represent more than 70% of primary brain tumors. Even following an aggressive therapies, the mean survival rate of patients with these tumors is less than one year after diagnosis. Chemotherapy based on alkyklating agents, such as temozolomide (TMZ) has been reported to increase the survival rate. N7-metyl-G and N3-metyl-A adducts comprise more than 80% of the DNA lesions induced by TMZ and are processed by the base excision repair process (BER). There is evidence in the literature suggesting that the resistance to TMZ could be caused, in part, by an efficient repair by BER pathway, although few studies have focused on this subject. Metoxiamine (MX) is an effective BER inhibitor, which has been investigated as a conceivable treatment for different kinds of tumor, due to its synergistic effect with antitumoral drugs, such as TMZ. In the present study, the cellular responses to TMZ treatment associated or not with MX were evaluated in giloblastoma (GBM) cell lines. Several parameters were analyzed, such as cytotoxicity (24 h), cellular survival (120 h) and clonogenic efficiency (10 days after treatment), DNA damage and repair kinetics (after 2, 6, 12 and 24 h of recovery time), apoptosis induction (24, 48 and 72 h) and alterations in gene expression (24, 48 e 72h) for genes playing role in BER pathway. The treatment with TMZ 100 -1000 M (during 24 h) was cytotoxic for all GBM cell lines tested (U87, U343, U251, U138 and T98G), as analyzed after 120 h, with the T98G cell line being be the most resistant to TMZ; besides, T98G was the only one to present significant differences (p 0,05) in survival rates measured between TMZ treatment and TMZ combined with MX. Thus, T98G cells were selected for the subsequent experiments and for the study of the pathways implicated in TMZ resistance. The clonogenic efficiency of T98G cells was reduced under TMZ treatment (100 - 800 M) with significant differences for treatments above 400 M. In addition, the combined treatment TMZ plus MX significantly increased the cytotoxic effects, even for the lowest concentration. The comet assay showed higher percentage of DNA damage for both treatment modalities (TMZ and TMZ+MX) at 2 and 6 h of recovery, with significant differences between treatments for 2 h. Following 12 and 24 h of recovery, the amount of DNA damage reached the control levels, indicating the repair of DNA breaks. Apoptosis induction in T98G cells showed the highest frequency (24.2%) at 72h for 600 M TMZ, while the highest apoptosis induction (47.7%) was observed for the same concentration combined to MX. Quantitative gene expression analysis performed for three genes, APE1, FEN1 and XRCC1, showed a reduced expression of APE1 and FEN1 for the combined treatment. Western blot analysis demonstrated that APE1 was less expressed for all kind of treatments, probably due to AP-sites blockade caused by the inhibitor MX. In addition, FEN1 showed low levels of expression at 48h and 72h, indicating the inhibition of BER pathway downstream to the AP removal by APE1. On the other hand, PCNA expression was higher for the combined treatment (24h and mainly 48h), suggesting its induction probably due to increased DNA damage. Therefore, the present results demonstrated that the association of TMZ with MX interfered with the expression of proteins involved in BER, thus, reducing the clonogenic efficiency of T98G cells, probably as a consequence of the high production of unrepaired DNA-MX adducts, leading to cell death, including apoptosis. These data show that the modulation of BER is a promising strategy for magnifying the therapeutic impact of TMZ, and in the next future, this strategy may embrace the option to establish novel and efficient therapy protocols for the treatment of gliomas with alkylating agents.
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Restovic, Valderrama Maria Inés. "Compilador ASN.1 e codificador/decodificador para BER." [s.n.], 1992. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259533.
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Orientador: Manuel de Jesus MendesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Neste trabalho apresenta-se uma ferramenta chamada Compilador ASN.1, cujo objetivo é fornecer uma representação concreta para a sintaxe abstrata ASN.1, de forma que, as especificações das PDU's dos protocolos de aplicação, geralmente escritas em ASN.1, possam ser utilizadas computacionalmente. Uma das funções prioritárias da camada de apresentação de um protocolo de comunicação é produzir uma codificação dos valores destas PDU's, baseando-se nas regras definidas pela norma BER. Assim, o compilador deve fornecer numa segunda tarefa, as rotinas de codificação e decodificação específicas para cada PDU compilada, utilizando um conjunto de funções que se encontram em duas bibliotecas auxiliares que realizam estas conversões
Abstract: This work presents a tool called "Compilador ASN.1", which main objective is to provide a concrete representation for the abstract syntax ASN.1, in order to translate the application protocol PDU's specification, written in ASN.1, to the C language. One of the main functions of the presentation layer is produce an encode-decode for the PDU's data values, based on the BER norm. Therefore, a second compiler task is to provide the specific encode-decode routines for each compiled PDU, using a function set available in two complementary libraries that carry out these conversions
Mestrado
Automação
Mestre em Engenharia Elétrica
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Selvarathinam, Anand Manivannan. "High throughput low power decoder architectures for low density parity check codes." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2529.
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A high throughput scalable decoder architecture, a tiling approach to reduce the
complexity of the scalable architecture, and two low power decoding schemes have been
proposed in this research. The proposed scalable design is generated from a serial
architecture by scaling the combinational logic; memory partitioning and constructing a
novel H matrix to make parallelization possible. The scalable architecture achieves a high
throughput for higher values of the parallelization factor M. The switch logic used to
route the bit nodes to the appropriate checks is an important constituent of the scalable
architecture and its complexity is high with higher M. The proposed tiling approach is
applied to the scalable architecture to simplify the switch logic and reduce gate
complexity.
The tiling approach generates patterns that are used to construct the H matrix by
repeating a fixed number of those generated patterns. The advantages of the proposed
approach are two-fold. First, the information stored about the H matrix is reduced by onethird.
Second, the switch logic of the scalable architecture is simplified. The H matrix information is also embedded in the switch and no external memory is needed to store the
H matrix.
Scalable architecture and tiling approach are proposed at the architectural level of the
LDPC decoder. We propose two low power decoding schemes that take advantage of the
distribution of errors in the received packets. Both schemes use a hard iteration after a
fixed number of soft iterations. The dynamic scheme performs X soft iterations, then a
parity checker cHT that computes the number of parity checks in error. Based on cHT
value, the decoder decides on performing either soft iterations or a hard iteration. The
advantage of the hard iteration is so significant that the second low power scheme
performs a fixed number of iterations followed by a hard iteration. To compensate the bit
error rate performance, the number of soft iterations in this case is higher than that of
those performed before cHT in the first scheme.
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Pan, Yaobin. "Impact of DOA (direction of arrival) : in 4G MIMO Systems." Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-42158.
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Yaskoff, Nicholas Thomas. "ANALYSIS, SIMULATION, AND EXPERIMENTS FOR ADDITIVE NARROWBAND COMMUNICATION SYSTEMS." Ohio University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1180713870.
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Ramos, Sparrow Oswaldo. "Modélisation et conception d’un récepteur non cohérent ultra large bande pour les communications ULB radio impulsionnelle dans la bande 3-5 GHz." Thesis, Nice, 2014. http://www.theses.fr/2014NICE4091/document.
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Ce travail de recherche est basé sur la technologie Ultra Large Bande (ULB), en particulier pour des applications bas débit (standard IEEE 802.15.4) tels que les réseaux de capteurs, les transmissions WPAN ou encore WBAN. La modélisation et la conception d’un récepteur non cohérent ULB pour les communications radio impulsionnelles ont été réalisées. Un des facteurs les plus importants dans les communications ULB est la sensibilité du récepteur, qui détermine la portée de transmission maximale. Un autre facteur aussi important est la consommation d’énergie qui influence directement la durée de vie de la source d’alimentation (batterie). Dans ce contexte, nous présentons dans le chapitre I une introduction sur la technologie ULB et ses diverses applications. Le chapitre II présente la modélisation au niveau système ainsi que d’une étude comparative des récepteurs non cohérents basés sur la détection d’énergie et la pseudo-Détection d’énergie. Dans le chapitre III sont présentés la méthode de conception et de réalisation d’un récepteur non cohérent ULB dans la bande de 3-5 GHz, ainsi que les résultats de mesure et ses performances en termes de sensibilité et de consommation d’énergie. Finalement, le chapitre IV présente une étude théorique sur les différents modes de fonctionnement du transistor MOS afin de mieux comprendre le fonctionnement de chaque bloc du récepteur. Cela permet de proposer de nouvelles architectures pour la détection d’énergie. Enfin, à partir de ces études nous réalisons l’optimisation du récepteur en termes de sensibilité et de consommation d’énergieThis research is based on Ultra Wide Band (UWB) technology, in particularly for low-Rate applications such as sensor network, WPAN and WBAN (for the standard IEEE 802.15.4). The model and design of a non coherent receiver for UWB impulse radio communications has been completed. One of the most important factors in the UWB communications is the receiver sensitivity which determines the maximum transmission range. Another important factor is the energy consumption that determines the lifetime of the power source (battery). In this context, we present in Chapter I an introduction to UWB technology and its different applications. Chapter II deals with a modeling at the system level of non-Coherent receivers as well as a comparative study based on the energy detection and pseudo energy detection. In Chapter III is presented the method of design and implementation of a non-Coherent UWB receiver in the band of 3-5 GHz, as well as measurement results and performance in terms of sensitivity and power consumption. Finally, Chapter IV presents a theoretical study on the different modes of operation of the MOS transistor to understand the operation of each block of the receiver. This allows us to show the new architectures for energy detection and perform the optimization of receiver in terms of sensitivity and power consumption
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Wanschoor, Paul. "Impact de la déficience de NEIL1 sur l'inflammation médiée par la voie des senseurs des ADNs cytosoliques." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASL032.
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Des recherches récentes ont établi des liens essentiels entre les dommages à l'ADN, le stress réplicatif et l'inflammation, révélant ainsi un mécanisme complexe dans lequel les fragments d'acides nucléiques résultants sont exportés dans le cytosol. Une fois dans le cytosol, ces fragments peuvent être détecté par des senseurs cellulaires tels que cGAS et RIG1, qui, avec l'aide respective de STING ou MAVS, déclenche la production de cytokines inflammatoires et l'activation des réponses immunitaires innées ou des voies de la mort cellulaire. Cette découverte souligne l'importance cruciale des voies de signalisation des senseurs pour la compréhension des interactions entre dommages à l'ADN, inflammation et réponse immunitaire. La capacité à cibler spécifiquement ces voies de signalisation dans la thérapie anticancéreuse, offre des possibilités d'élimination ciblée des cellules cancéreuses et contribue aux effets abscopaux observés après irradiation grâce à l'activation du système immunitaire. La compréhension approfondie des mécanismes sous-jacents à la production de ces fragments d'acides nucléiques pourrait permettre d'identifier de nouvelles cibles thérapeutiques pour moduler l'inflammation et renforcer les réponses thérapeutiques.Le stress oxydatif induit par des traitements anticancéreux tels que la radiothérapie, peut entraîner des dommages à l'ADN et provoquer un stress réplicatif. Cette thèse se concentre sur le rôle du mécanisme de réparation par excision de base (BER). Au sein du BER, j'ai porté une attention particulière au rôle d'une glycosylase, protéine clef qui initie la voie du BER en reconnaissant les bases endommagées et en les excisant notamment lors de la réplication de l'ADN. En étudiant l'interaction entre le BER et les voies de signalisation des senseurs de l'ADN cytosolique, cette recherche vise à approfondir notre compréhension de l'impact de la gestion des dommages oxydatifs et de l'inflammation dans le contexte du cancer.Une meilleure compréhension de ces interactions pourrait non seulement permettre d'améliorer les réponses thérapeutiques anticancéreuses, mais également contribuer à prédire les résultats des traitements chez les patients. En conclusion, l'étude de ces mécanismes complexes ouvre la voie à de nouvelles perspectives thérapeutiques dans la lutte contre le cancer, en exploitant les liens intimes entre dommages à l'ADN, inflammation et réponse immunitaire pour développer des thérapies plus ciblées et efficacesRecent studies have established essential links between DNA damage, replicative stress, and inflammation, revealing a complex mechanism in which the resulting nucleic acid fragments are exported into the cytosol. Once in the cytosol, these fragments can be detected by cellular sensors such as cGAS and RIG1, which, with the help of STING or MAVS repectively, trigger the production of inflammatory cytokines and activation of innate immune responses or cell death pathways. This discovery underlines the crucial importance of sensor signaling pathways for understanding the interactions between DNA damage, inflammation and immune response. The ability to specifically target these signaling pathways in cancer therapy, offers possibilities for targeted elimination of cancer cells and contributes to the abscopal effects observed after irradiation through activation of the immune system. A deeper understanding of the mechanisms underlying the production of these nucleic acid fragments could lead to the identification of new therapeutic targets to modulate inflammation and enhance therapeutic responses.Oxidative stress induced by anticancer treatments such as radiotherapy, can lead to DNA damage and cause replicative stress. This thesis focuses on the role of the base excision repair (BER) mechanism. Within BER, special attention has been paid to the role of a glycosylase, a key protein that initiates the BER pathway by recognizing damaged bases and excising them, notably during DNA replication. By elucidating the interaction between BER and cytosolic DNA sensor signaling pathways, this research aims to deepen our understanding of the impact of oxidative damage management and inflammation in the context of cancer.A better understanding of these interactions could not only lead to improve anticancer therapeutic responses, but also help predict treatment outcomes in patients. In conclusion, the study of these complex mechanisms opens the way to new therapeutic perspectives in the fight against cancer, by exploiting the intimate links between DNA damage, inflammation, and immune response to develop more targeted and effective therapies
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Pérez, Rodenas Ezequiel. "QAM and PSK Modulation Schemes under Impulsive Noise." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-11943.
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Nowadays most of the communications systems are designed considering only to work under AWGN (Additive White Gaussian Noise). But the implementation of wireless systems in industrial facilities brings different kind of interference from machines or any other kind of electronic devices. Some of them are sources of randomly and high power noise, which commonly is known as impulsive noise. The objective in this thesis is to study the impact of the impulsive noise on a communication using QAM (Quadrature Amplitude Modulation) and PSK (Phase-Shift Keying) schemes, by observing the BER (Bit Error Rate) and the APD (Amplitude Probability Distribution). For that, it is developed a measurement method that will be used in a real industrial environment in future work. The content of this thesis is divided in two parts. In the first part is made a program in MATLAB to simulate the communication through a noisy channel. Then is developed a measurement method which is tested in three different ways corresponding to 3 different outputs of an spectrum analyzer, namely, 20,4 MHz IF output, video output and IQ data output. The relation of impulsive noise is presented in the second part with different statistical properties in the BER and the APD, in the setup with the best performance. At the end of the thesis a concluding section summarizes the results obtained during the work and some lines of future work in a real industrial environment with the developed method.
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Wang, Yongjian, and Tingxian Zhou. "THE RESEARCH OF A NEW MULTIUSER DETECTION SCHEME COMBINING DECORRELATING DETECTOR AND PARTIAL PARALLEL INTERFERENCE CANCELLER." International Foundation for Telemetering, 2004. http://hdl.handle.net/10150/604934.
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International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, CaliforniaThe decorrelating detector can afford good data estimates because it does not need to know many parameters of the received signal. However, it shows great performance deprivation when the background noise is high. On the other hand, partial parallel interference canceller(PPIC) has the potential to combat the near-far problem and have much lower computation complexity. But its performance depends on the initial data estimate. An improved PPIC scheme is proposed in this paper to combat the near-far problem. It utilizes the advantages of the two detectors by combining them. The focus of this paper is on the BER performance and the near-far resistance capability of the proposed scheme. Computer simulations demonstrate that the proposed detector has good BER performance and near-far resistance capability.
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Dang, Xiaoyu. "A Bit Error Rate Analysis of Offset QPSK over the Aeronautical Telemetry Multipath Channel." International Foundation for Telemetering, 2003. http://hdl.handle.net/10150/605567.
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International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, NevadaThe impact of multipath fading parameters on the probability of error for Offset QPSK (OQPSK) is derived. The multipath fading channel is modeled using the aeronautical telemetry channel model [1-2]. Expressions for the probability of bit error are derived that are a function of the multipath model parameters. The expressions are shown to agree with computer simulations and show that a strong multipath reflection with a short delay causes much more degradation than a weak multipath reflection with a long delay.
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Mainali, Miraj. "Performance Evaluation of M-ary APSK using Punctured Trellis Coded Modulation (TCM) for DVB Applications." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1523281892780375.
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Wang, Yun, and Wenxuan Jiang. "Statistical Processing of IEEE 802.15.4 Data Collected in Industrial Environment." Thesis, Mittuniversitetet, Institutionen för informationsteknologi och medier, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-19619.
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Wireless sensor network, which is constitute of autonomous sensors, is used for monitoring physical or environmental conditions like temperature, sound, pressure, and so on. The dispersed sensors or nodes will respectively pass their data through the network to the main location. Currently, several standards are ratified or in developing for wireless sensor network, like Wireless Hart, ISA, 100.11a, WIA-PAA, IEEE 802.15.4, etc. Among the standards, Zigbee is often used in industrial applications that require short-range and low-rate wireless transfer. In the research, all the data is collected under industrial environment using IEEE 802.15.4 compliant physical layer, some packets are interfered only by multi-path fading while others are also interfered by Wi-Fi interference. The goal of the thesis is to find out the dependence between the received power (RSS), correlation value (CORR) and bit error rate (BER) of the received message, and their distribution in situations both when the packet is lost or not. Besides, the performance of bit error rate such as the distribution and the features of burst error length under Wi-Fi interference or not will also be tested. All of them are based on a precise statistical processing.
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Samaras, Konstantinos. "Performance analysis of wireless infrared communication systems." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300127.
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Bow, R. T. "HARDWARE PERFORMANCE FOR BINARY GMSK WITH BT=1/5." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608734.
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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, NevadaThe design, implementation, and performance of a digital modem employing Gaussian minimum shift keying (GMSK) is described. The GMSK modem is implemented in field programmable gate array (FPGA) chips, and a laboratory test setup was developed to validate its performance for a signal BT value of 1/5. The measured spectrum of the GMSK modem and its bit error rate (BER) performance, which are found in very close agreement with those of theory and simulation, are presented in this paper.
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Dusitsin, Krid, and Kurt Kosbar. "Accuracy of Computer Simulations that use Common Pseudo-random Number Generators." International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/609238.
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International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, CaliforniaIn computer simulations of communication systems, linear congruential generators and shift registers are typically used to model noise and data sources. These generators are often assumed to be close to ideal (i.e. delta correlated), and an insignificant source of error in the simulation results. The samples generated by these algorithms have non-ideal autocorrelation functions, which may cause a non-uniform distribution in the data or noise signals. This error may cause the simulation bit-error-rate (BER) to be artificially high or low. In this paper, the problem is described through the use of confidence intervals. Tests are performed on several pseudo-random generators to access which ones are acceptable for computer simulation.
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Rajyalakshmi, P. S., and R. K. Rajangam. "Data Handling System for IRS." International Foundation for Telemetering, 1987. http://hdl.handle.net/10150/615329.
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International Telemetering Conference Proceedings / October 26-29, 1987 / Town and Country Hotel, San Diego, CaliforniaThe three axis stabilized Indian Remote Sensing Satellite will image the earth from a 904 Km polar - sun synchronous orbit. The payload is a set of CCD cameras which collect data in four bands visible and near infra-red region. This payload data from two cameras, each at 10.4 megabits per sec is transmitted in a balanced QPSK in X Band. The payload data before transmission is formatted by adopting Major and Minor frame synchronizing codes. The formatted two streams of data are differentially encoded to take care of 4-phase ambiguity due to QPSK transmission. This paper describes the design and development aspects related to such a Data Handling System. It also highlights the environmental qualification tests that were carried out to meet the requirement of three years operational life of the satellite.
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Guin, Ujjwal. "DESIGN FOR BIT ERROR RATE ESTIMATION OF HIGH SPEED SERIAL LINKS." Master's thesis, Temple University Libraries, 2010. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/105599.
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Electrical EngineeringM.S.E.
High-speed serial links in modern communication systems often require the Bit-Error-Rate (BER) to be at the level of 10 −12 or lower. From the industry perspective, major drawbacks in high volume production test for the serial links with low BER are the excessive test time for comparing each captured bit for error detection and costly instrumentation. In this thesis, we focus on developing a novel BER estimation methodology and its implementation. We propose a novel BER estimation methodology and an effective self-test system, which not only eliminates the usage of expensive measuring instruments, but also significantly reduces the test time. In the proposed BER estimation, we show that the total jitter (TJ) spectral information of a test SerDes is successfully estimated from the known TJ distribution of a golden SerDes. We propose a novel BER estimation formula that incorporates not only the TJ spectral information of the serial data, but also the TJ spectral information of the recovered clock. Our proposed estimation formula enables efficient BER estimation without excessive test time, and its accuracy does not depend on the jitter present in the serial data stream of the SerDes. The experimental results demonstrate that the test time for the proposed BER estimation is in the order of seconds, which translates to the test time savings of more than hundred times compared to the traditional BER measurement for the same accuracy. To implement the proposed BER estimation methodology, we have developed a novel time-to-digital converter (TDC). This design effectively measures the delay between two signals and converts it into the digital format. Performance of the TDC has been evaluated and presented using ModelSim and SPICE simulation.
Temple University--Theses
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Fan, Yongquan. "Accelerating jitter and BER qualifications of high speed serial communication interfaces." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86531.
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High-Speed Serial Interface (HSSI) devices have witnessed an increased use in communications. As a measure of how often bit errors happen, Bit Error Rate (BER) performance is of paramount importance in any communication interface. The bit errors in HSSIs are in large part due to jitter. This thesis investigates the topic of accelerating the jitter and BER testing and characterization [1].The thesis first proposes a new algorithm, suitable for extrapolating the receiver jitter tolerance performance from higher BER regions down to the 10-12 level or lower [2]. This algorithm enables us to perform the jitter tolerance characterization and production test more than 1000 times faster [3]. Then an under-sampling based transmitter test scheme is presented. The scheme can accurately extract the transmitter jitter and finish the whole transmitter test within 100ms [4] while the test usually takes seconds. All the receiver and transmitter testing schemes have been successfully used on Automatic Test Equipment (ATE) to qualify millions of HSSIs with speed up to 6 Gigabits per second (Gbps).
The thesis also presents an external loopback-based testing scheme, where a novel jitter injection technique is proposed using the state-of-the-art phase delay lines. The scheme can be applied to test HSSIs with data rate up to 12.5 Gbps. It is also suitable for multi-lane HSSI testing with a lower cost than pure ATE solutions. By using high-speed relays, we combine the proposed ATE based approaches and the loopback approach along with an FPGA-based BER tester to provide a more versatile scheme for HSSI post-silicon validation, testing and debugging [5]. In addition, we further explore the unparallel advantages of our digital Gaussian noise generator in low BER evaluation [6].
Les interfaces sérielles à haute vitesse (interfaces HSSI) ont connu une utilisation accrue dans les télécommunications. Le taux d'erreur sur les bits (BER), mesure de la fréquence des erreurs, est d'une importance cruciale dans les interfaces modernes de télécommunication. Cette thèse traite de l'accélération de la caractérisation du vacillement et des tests BER.
Cette thèse propose tout d'abord un nouvel algorithme, approprié pour l'extrapolation de la performance de la tolérance au vacillement d'un récepteur pour un taux d'erreur sur les bits (BER) à un niveau de 10-12 ou moins. Cet algorithme permet de caractériser la tolérance au vacillement dans les tests de production plus de 1000 fois plus rapidement. Ensuite, une conception de transmetteur à sous-échantillonnage est présenté. Cette conception permet d'extraire précisément le vacillement du transmetteur et de compléter les tests de ce dernier en moins de 100 ms alors que ces tests durent normalement plusieurs secondes. Toutes les méthodes de test de récepteurs et de transmetteurs ont été utilisées avec succès sur un équipement d'éssai automatique (ATE) pour qualifier des millions d'interfaces HSSI à des vitesses allant jusqu'à 6 gigabits par seconde (6 Gbps).
Cette thèse présente aussi une conception de test en bouclage où une nouvelle méthode d'injection de vacillement est proposée en utilisant des lignes de délai de phase. Cette méthode peut être appliquée pour tester des interfaces HSSI avec un taux de transfer allant jusqu'à 12.5 Gbps. Elle permet aussi de tester des interface HSSI multi-lignes à un coût moindre qu'une solution utilisant un ATE. En utilisant des relais à haute vitesse, les approches sur ATE et par test en bouclage peuvent être combinées en incorporant un testeur de BER sur circuit intégré prédiffusé programmable (FPGA), ce qui permet une méthode de tests HSSI polyvalente pour la validation post-fabrication, les tests et le débogage. Finalement, nous explorons les avantages de notre générateur de bruit Gaussien dans l'évaluation de BER à bas niveau.
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Fonseca, E. Otto. "Approximation methods for the BER performance : analysis of wireless communications systems." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83864.
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Performance evaluation is a critical stage in the design of every communications system. This task often presents difficulties related especially to computational requirements. This thesis presents a general method that can be used to provide closed form expressions of low complexity for the average Bit Error Rate (BER) of different communication technologies.The method is based on numerical optimization of the parameters of finite series whose mean values can be calculated easily. To that end, a new error measure that addresses specific needs of the approximations needed for communications problems is proposed as the cost function of the optimization procedure.
To illustrate the proposed method, we consider two representative cases: Binary Phase Shift Keying (BPSK) transmissions over Inter-Symbol Interference (ISI)-inducing channels and adaptive Code Division Multiple Access (CDMA) linear receivers. Specific low computational complexity expressions are provided for the BER performance of these systems. It is demonstrated by numerical studies that the derived expressions provide satisfactory accuracy, and can outperform previously proposed methods.
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Lin, Jinsong, and Kamilo Feher. "BANDWIDTH EFFICIENCY AND BER PERFORMANCE OF ENHANCED AND FEC CODED FQPSK." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/607727.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaBit error rate (BER) and bandwidth efficiency of several variations of enhanced Feher patented quadrature phase shift keying (FQPSK) [1] are described. An enhanced FQPSK increases the channel packing density of that of the IRIG 106-00 standardized FQPSK-B by approximately 50% in adjacent channel interference (ACI) environment. As the bandwidth efficiency of FQPSK-B DOUBLES (2×) that of pulse code modulation/Frequency modulation (PCM/FM) [5], the enhanced FQPSK, with a simpler transceiver than FQPSK-B, has a channel packing density of TRIPLE (3×) that of PCM/FM. One of the other enhanced FQPSK prototypes has an end to end system loss of only 0.4 dB at BER=1x10^(-3) and 0.5 dB at BER=1x10^(-4) from ideal linearly amplified QPSK theory. The enhanced FQPSK has a simple architecture, thus is inexpensive and has small size, for ultra high bit rate implementation. With low redundancy forward error correction (FEC) coding which expands the spectrum by approximately 10%, further improvement of about 3-4.5dB E N b o is attained with NLA FQPSK-B and enhanced FQPSK at BER=1x10^(-5) .
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Friend, Daniel. "BER ANALYSIS OF AN F-16 TEST RUN AT EDWARDS AFB." International Foundation for Telemetering, 1997. http://hdl.handle.net/10150/609810.
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International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, NevadaThis paper analyzes the bit error rates (BER) using data recorded during an F-16 test at Edwards Air Force Base in September, 1996. The effects of multipath fading on BER are presented. It is shown that significant increases in BER can occur when the received signal power remains at an acceptable level. Recordings of the received power spectrum during the test show that these BER increases are caused by frequency selective fades due to multipath interference. This paper illustrates that in these cases, significant data degradation can occur without drops in the received signal power.
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Kühn, Katharina [Verfasser]. "Über Grenzen - Feminismus in Russland in postkolonialer Perspektive / Katharina Kühn." Gießen : Universitätsbibliothek, 2021. http://d-nb.info/1236385632/34.
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Cros, Julien. "OGG1 et NEIL1, de nouvelles cibles pour la lutte contre le cancer : recherche et caractérisation fonctionnelle et structurale d’inhibiteurs." Thesis, Orléans, 2021. https://theses.univ-orleans.fr/prive/accesESR/2021ORLE3145_va.pdf.
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L’ADN de tout organisme est continuellement endommagé par des agents physiques ou chimiques d’origines endogène ou exogène. Les dommages de l’ADN qui en résultent peuvent être à l’origine de l’apparition de mutations ou de mort cellulaire. Pour pallier à ces effets délétères, les organismes ont développé des systèmes de réparation de l’ADN. Le système de réparation par excision de base (BER) est la voie majeure de réparation des bases endommagées et est initié par des ADN glycosylases telles que hOGG1 et hNEIL1. Ces enzymes reconnaissent spécifiquement les bases lésées et les éliminent. Paradoxalement, les réparations initiées par ces protéines peuvent diminuer l’effet thérapeutique de certains traitements, notamment anti-cancéreux. En exploitant le principe de létalité synthétique, le ciblage thérapeutique de hOGG1 et hNEIL1 pourrait être pertinent pour lutter contre certains cancers, mais aussi contre des maladies neurodégénératives (Huntington) ou des processus inflammatoires pathologiques. Au travers du criblage « moyen débit » de banques de petites molécules naturelles ou synthétiques, mon travail de thèse a consisté en l’identification de nouveaux inhibiteurs sélectifs de hNEIL1 et hOGG1 et en la caractérisation de leur mode d’action par des études biochimiques et structurales. Si nous avons pu mettre en lumière des fonctions chimiques essentielles et quelques déterminants structuraux et fonctionnels relatifs à leurs modes d’action, de nombreuses zones d’ombre demeurent et mériterons d’être explorés dans le futur. En revanche, l’utilisation d’un homologue archéen de hOGG1, l’enzyme PabAGOG, a permis de proposer un modèle tridimensionnel cohérent d’un complexe hOGG1/inhibiteur pour l’un des meilleurs inhibiteurs que nous avons identifiés. Finalement, ces nouveaux composés comptent parmi les meilleurs inhibiteurs de hOGG1 et hNEIL1 identifiés à ce jour et certains d’entre eux devraient bénéficier d’une évaluation in celluloDNA is continuously damaged by physical or chemical agents from endogenous or exogenous sources. These damages can induce mutation or cell death. To counteract these deleterious effects, organisms have developed DNA repair systems. The Base Excision Repair System (BER) is the major pathway to repair damaged bases. It is initiated by DNA Glycosylases such as hNEIL1 and hOGG1 which specifically recognize and remove oxidized bases. However, in some situation like conventional cancer treatment, the repairs initiated by these enzymes can lead to therapeutic resistance. Therefore, based on the synthetic lethality concept, selective inhibition of hNEIL1 and hOGG1 could be relevant in some pathologic contexts like cancer, but also against neurodegenerative diseases (Huntington) or pathological inflammatory processes. This thesis work aimed to identify new selective inhibitors of hNEIL1 and hOGG1 with a "medium throughput" screening of natural or synthetic small molecule libraries, and to characterize their mode of action through biochemical and structural studies. Although we identified some essentials chemicals functions and some leads to understand the action mode of our inhibitors, many areas remains unveiled and deserve to be explored in the future. However, the use of an archaeal homologue of hOGG1, the enzyme PabAGOG, has allowed us to propose a coherent three-dimensional model of an hOGG1/inhibitor complex for one of the best inhibitors we have identified. Finally, these new inhibitors are among the best inhibitors of hOGG1 and hNEIL1 identified to date and some of them will undergo in cellulo evaluation
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Mori, Yoshifumi. "OGG1 protects mouse spermatogonial stem cells from reactive oxygen species in culture." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263547.
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Chalasani, Sri Lakshmi. "RESOLUTION OF PROXIMAL OXIDATIVE BASE DAMAGE AND 3′-PHOSPHATE TERMINI FOR NONHOMOLOGOUS END JOINING OF FREE RADICAL-MEDIATED DNA DOUBLE-STRAND BREAKS." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5237.
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Clustered damage to DNA is a signature mark of radiation-induced damage, which involves damage to the nucleobases and/or DNA backbone. Double-strand breaks created by damaging agents are detrimental to cell survival leading to chromosomal translocations. Normal cells employ Non-homologous end-joining because of its faster kinetics, to suppress chromosomal translocations. However, the presence of complex DNA ends constitutes a significant challenge to NHEJ. Location of Thymine glycol (Tg) at DSB ends was a potential hindrance to end joining. The substrate with Tg at the third position (Tg3) from the DSB joined better than when present at the fifth position (Tg5). However, hNTH1 assay showed Tg5 to be a better substrate than Tg3 for BER, potentially explaining the increased Tg removal and decreased end joining of Tg5 in extracts. Nonetheless, there appeared to be no preference in the susceptibility of 5’-Tg substrates with Tg at the second and third positions from DSB ends.
Polynucleotide kinase phosphatase is crucial in restoring the 3′ hydroxyl, and 5′ phosphate ends at strand breaks. No other enzyme is known to possess PNKP’s activity in mammalian cells at DSBs. Experiments done with PNKP knockout cells have shown some activity similar to PNKP, which appeared to be a part of NHEJ and was not pharmacologically inhibited by PNKP inhibitor. Additionally, core NHEJ factors XRCC4 and XLF influenced the activities of PNKP.
Overall, these experiments suggest that Tg repair is dependent on the position from DSB and an alternative enzyme processes 3′- PO, and 5′-OH ends.
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Sidibe, Hallassy. "Occupation humaine et environnement dans la région lacustre de l'Issa-Ber, Mali." Paris, EHESS, 1993. http://www.theses.fr/1993EHES0004.
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Ce travail est une etude de geographie humaine. Son objet est delimite par le triptyque suivant : "occupation humaine, environnement, region lacustre de l'issaber". Ainsi precisee, la problematique generale est issue de celle d'un programme d'inventaire des sites archeologiques du mali. La question qui se pose est de savoir quelle correlation significative on peut etablir entre les modes de peuplements actuels et les traces de peuplements anciens et, d'autre part, entre leurs activites economiques, leurs mode de vie et les environnements corresponcants. La region lacustre de l'issa-ber offre a cet egard un champ d'etude particulierement riche comme le montrent la presence et la densite des sites archeologiques. Elle a represente dans le passe un territoire favorable au peuplement, a la diversite et a la continuite des occupations des activites humaines. A cela, une serie de raisons : la presence de l'eau de l'herbe et de terres fertiles ; la position geographique privilegiee au contact entre loe sahara, au nord, et la savane au sud ; la naissance d'un reseau urbain bien structure et relie par le fleuve : gao, tombouctou et djenne, qui furent au moyen-age, a la fois des metropoles commerciales, intellectuelles et religieuses de renommee internationale et, enfin, l'existence d'un environnement naturel exempt de trypanosomiase, ayant permis un accroissement demographique relativement constant. Autant d'elements favorables, qui ont fait de ce milieu un grand foyer d'attraction, de fixation de populations pratiquant des activites variees allant de la cueillette, de la peche, de laThe subject of this study of human geography comes from an inventory programme of archaeological sites in mali in order to establish the correlation between first, actual human settlments and old human traces andsecond, their economical activities, their way of life and their respective environment. The density of archaeological sites indicates that this coutry represented in the past a favourable place to human settlment because of water and grass ressources and fertile ground. Its privileged localization between the sahara to the north and the savannah to the south ; an urban network good structured and joined by the river niger (gao, tombouctou, djenne) and an environment exempt from trypanosomiase, furthered a constant increase in human population. Such avantages make this country attractive because of a large variety of activities as picking, fishing, hunting, metallurgy and agriculture. The recent evolution of this lake country depend at once on the evolution of economical and social processes and their combination with the fluctuations of natural ressources (specially climatic and water ressources). The analyse of respective rules of human occupation and climatic and hydrological modifications and their combination provides indications of possible future developments of this country
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McCorduck, James A., and Kamilo Feher. "COMPATIBILITY OF IRIG-106-00 STANDARDIZED FEHERPATENTED FQPSK WITH OTHER DATA LINKS AND WIDEBAND W-CDMA." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/607701.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaThe interoperability of Feher-patented Quadrature Phase Shift Keying (FQPSK) systems with future and legacy data links is discussed in this paper. In particular, the benefits of “forward” interoperability with 3G (3rd Generation) wireless systems such as WCDMA (Wideband Code Division Multiple Access) up to 40 Mchips/sec are highlighted. Other proposals of forward interoperability with future data links include an enhanced, ultra-bandwidth efficient FQPSK and 16-state FQAM (Feher’s Quadrature Amplitude Modulation) architectures. In addition, since FQPSK based systems have been proven in “dual use” systems and extensively tested and evaluated by the Department of Defense (DoD) and NASA, the analysis of “backward” interoperability with legacy data links such as GSM is also included in this paper.
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Lui, Gee L., and Kuang Tsai. "VITERBI AND SERIAL DEMODULATORS FOR PRE-CODED BINARY GMSK." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608732.
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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, NevadaThree different demodulators applicable to the coherent demodulation of binary Gaussian Minimum Shift Keying (GMSK) signal are described and their performance compared. These include a near-optimal trellis demodulator, which utilizes two matched filters and Viterbi algorithm to carry out maximum likelihood sequence estimation, and a singlefilter threshold demodulator with and without pulse equalization. The performance of these demodulators in noise and adjacent channel interference (ACI) are compared for several signal BT products. The equalized threshold demodulator is shown to perform nearly as well as the near-optimal trellis demodulator in additive white Gaussian noise (AWGN), and substantially outperform the trellis demodulator under severe ACI condition.
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Kudlička, Miroslav. "Model terminálu VSAT." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218635.
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This work deals with the description of the communication using the VSAT satellite network. A used network topology, frequency bands, satellite orbits and also an access technology are defined. The next part is focused on the VSAT terminal, where the block diagram is shown. A model of the indoor unit IDU is designed in the system background of Ansoft Designer. Individual parts of the system model are analyzed in terms of input variables. The results of the simulation are shown. The curves of BER before Viterbi decoding and after Viterbi decoding are shown too.
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Gatschke, W., M. Matthes, D. Gawlik, and Ingrid Stephan. "Bestimmung der Neutronenflüsse in der drehbaren Bestrahlungseinrichtung im BER-II des HMI Berlin." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-32616.
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Zur Aktualisierung der Neutronenparameter in der drehbaren Bestrahlungseinrichtung des rekonstruierten BER-II wurde der im Forschungszentrum Rossendorf entwickelte Mehrkomponentenaktivierungsdetektor eingesetzt. Durch das umfangreiche Datenmaterial sind axiale und radiale Neutronenflußverläufe bestimmt und es gelingt ein eindeutiger Bezug von Meßwert zur Bestrahlungsprobe.
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Edalat, Farinaz 1979. "Effect of power amplifier nonlinearity on system performance metric, bit-error-rate (BER)." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/87438.
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Raddo, Thiago Roberto. "Proposal of a new approach for BER evaluation of multirate, multiservice OCDMA systems." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18155/tde-16102012-105005/.
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The continuous evolution of the optical communication technology in the last few years has allowed the growing users demand for higher bandwidth to be satisfactorily attended. This new demand is mainly attributed to the growing popularity of bandwidth-intensive networking applications, such as Internet protocol television (IPTV), high-definition television (HDTV), e-learning, e-health, super high-definition (SHD) class digital movies, and e-culture based on 3-D full-HD video. These applications will eventually require differentiated service types and diversified data rates. As a result, capability of supporting differentiated-quality of service (QoS) and multirate transmission are becoming a challenge for future optical networks. Among many multiplexing techniques, optical code-division multiple-access (OCDMA) constitutes a potential candidate for next generation optical networks, particularly due to features like asynchronous operation, simplified network control, easy addition of new users, and possibility of differentiated-QoS at the physical layer. The performance of this access technique is mainly limited by multiple-access interference (MAI). Although in multirate, multiservice OCDMA systems MAI is considered to be binomially distributed, others probability distributions for the MAI analyzes and consequently the bit error rate (BER) have been used as an approximation. In this context, this dissertation proposes a new formalism to evaluate the BER performance of 1-D and 2-D multirate, multiservice OCDMA systems considering MAI as binomially distributed, resulting in a more accurate BER expression. Also, the proposed approach does not require knowledge a priori of the generated code sequences themselves, which means that the system performance analysis is achieved more easily using only the code parameters. Furthermore, a multirate OCDMA system employing 1-D optical orthogonal code (OOC) and 2-D optical fast frequency hopping (OFFH) codes is also investigated. A performance comparison in terms of BER for the OOC-based system assuming both Poisson and binomial distribution for the MAI is investigated. A further comparison of an OFFH-based multirate system assuming both gaussian and binomial distribution for the MAI is also analyzed. It is shown that BER performance in multirate scenarios can be overestimated or underestimated by many orders of magnitude depending on the assumed distribution for the MAI and on the number of simultaneous users. Moreover, it is presented for the first time a hybrid OCDM/WDM optical packet switch capable of supporting multirate and differentiated-QoS transmission. The architecture of the proposed multirate switch and its performance in terms of packet loss probability are also presented. Finally, it is shown that using a gaussian or Poisson distribution for the MAI might not be appropriate for a reliable BER estimate, since they are not acceptable approximations to assess the performance of multirate, multiservice systems with good accuracy.A contínua evolução da tecnologia de comunicações ópticas observada nos últimos anos vem possibilitando atender a crescente demanda dos usuários por maior largura de banda. Esta nova demanda é atribuída principalmente à popularidade crescente de aplicações de banda larga, tais como TV por protocolo de Internet (IPTV), televisão de alta definição (HDTV), ensino online, e-saúde, filmes digitais de super alta definição (SHD) e e-cultura baseado em vídeo 3-D full-HD. Esta vasta gama de aplicações acabará por necessitar de tipos de serviços diferenciados e taxas de transmissão de dados diversificadas. Como resultado, capacidades de suportar diferenciamento de qualidade de serviço (QoS) e transmissão de múltiplas taxas estão se tornando um desafio para as redes ópticas futuras. Dentre muitas técnicas de multiplexação existentes, OCDMA constitui-se em um candidato potencial para as redes ópticas de próxima geração, particularmente devido a características como operação assíncrona, controle de rede simplificada, fácil adição de novos usuários, e também possibilidade de QoS diferenciado na camada física. O desempenho desta técnica de acesso múltiplo é limitado principalmente por interferência múltipla de acesso (MAI). Embora em sistemas OCDMA de múltiplas taxas e multiserviços a MAI deva ser considerada binomialmente distribuída, outras distribuições de probabilidade para a análise da MAI e, consequentemente, da BER têm sido utilizadas como uma aproximação. Neste contexto, este trabalho propõe um novo formalismo para avaliar o desempenho da BER de sistemas OCDMA 1-D e 2-D de múltiplas taxas e multisserviços considerando a MAI como binomialmente distribuída, o que resulta em uma expressão mais precisa para a BER. Além disso, o método proposto neste trabalho não requer conhecimento, a priori, das sequências de códigos geradas, o que significa que a análise do desempenho do sistema é obtida mais facilmente utilizando apenas os parâmetros do código. Um sistema OCDMA de múltiplas taxas empregando códigos 1-D OOC e 2-D OFFH será também investigado. Uma comparação do desempenho em termos de BER para o sistema baseado em OOC supondo tanto a distribuição de Poisson quanto a binomial para a MAI é investigada. De forma análoga, uma comparação para o sistema de múltiplas taxas baseado em OFFH supondo desta vez tanto a distribuição gaussiana quanto a binomial para a MAI também é analisada. É mostrado que a BER em cenários de múltiplas taxas pode ser superestimada ou subestimada em várias ordens de grandeza, dependendo da distribuição suposta para a MAI e do número de usuários simultâneos no sistema. Além disso, é apresentado pela primeira vez um switch óptico híbrido de pacotes OCDM/WDM capaz de prover transmissões de múltiplas taxas e serviços diferenciados. A arquitetura do switch proposto e seu desempenho em termos de probabilidade de perda de pacotes também são apresentados. Finalmente, é mostrado que o uso da distribuição gaussiana ou poissoniana para a MAI pode não ser apropriado para uma estimativa confiável de BER, uma vez que não são aproximações aceitáveis para avaliar o desempenho de sistemas de múltiplas taxas e multiserviços com boa precisão.
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Gatschke, W., M. Matthes, D. Gawlik, and Ingrid Stephan. "Bestimmung der Neutronenflüsse in der drehbaren Bestrahlungseinrichtung im BER-II des HMI Berlin." Forschungszentrum Rossendorf, 1994. https://hzdr.qucosa.de/id/qucosa%3A22087.
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Zur Aktualisierung der Neutronenparameter in der drehbaren Bestrahlungseinrichtung des rekonstruierten BER-II wurde der im Forschungszentrum Rossendorf entwickelte Mehrkomponentenaktivierungsdetektor eingesetzt. Durch das umfangreiche Datenmaterial sind axiale und radiale Neutronenflußverläufe bestimmt und es gelingt ein eindeutiger Bezug von Meßwert zur Bestrahlungsprobe.
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Medjahdi, Yahia. "Interference modeling and performance analysis of asynchronous OFDM and FBMC wireless communication systems." Phd thesis, Conservatoire national des arts et metiers - CNAM, 2012. http://tel.archives-ouvertes.fr/tel-00923188.
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Multicarrier systems are widely used today due to their robustness to multipath effects and efficient implementation using FFT. Orthogonal Frequency Division Multiplexing (OFDM) system is a class of multicarrier modulation which consists of splitting up a wide-band signal at a high symbol rate into several lower rate signals, each one occupying a narrower band. System performance improves because subcarriers experience flat fading channels and are orthogonal to one another. Recently, a number of papers have focused on a new alternative called Filter bank based multicarrier system (FBMC) which can offer a number of advantages over CP-OFDM system such as the improved spectral efficiency by not using a redundant CP and by having much better control of the out-of-band emission due to the time-frequency localized shaping pulses.Furthermore, asynchronism inherently exists in several communication systems due to many factors e.g. the propagation delays and the spatial distribution of users. As one of the most challenging issue in design of communication systems, the asynchronism can harmfully affect the system performance by causing the so-called asynchronous interference.In this dissertation, we investigate the impact of asynchronism on the performance of OFDM FBMC systems. First, we present a unified framework for multicarrier interference characterization and analysis in asynchronous environments. We propose a new family of interference tables that model the correlation between a given interfering subcarrier and the victim one, not only as a function of the spectral distance separating both subcarriers but also with respect to the timing misalignment between the subcarriers holders. These tables are derived for CP-OFDM, PHYDYAS-FBMC and IOTA-FBMC systems. Furthermore, the impact of the asynchronous interference on the average error rate and the average spectral efficiency of OFDM and FBMC systems is addressed. Based on computing the moment generating functions of the asynchronous interference power, simple new expressions for the exact evaluation of the average error rate and the average spectral efficiency are derived considering the frequency correlation fading between adjacent interfering subcarriers. These expressions significantly reduce the computation complexity of the performance evaluation.For each technique two scenarios are examined: fully-loaded network and partially loaded ones. The accuracy of the obtained expressions has been validated through different simulation results. In contrast to OFDM, FBMC waveforms are demonstrated to be less sensitive to timing asynchronism, due to the better frequency localization of the used prototype filters.
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Obruča, Martin. "Simulace přenosu DVB-T v prostředí MATLAB." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217992.
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This thesis deals with Matlab application developed for simulation of the DVB-T channel coder and decoder. The first part of this thesis includes description of terrestrial digital video broadcasting system and comparison with analogue television. Channel coding and OFDM modulation, used in the DVB-T standard, is described in detail. Application developed in the Matlab environment is described in the second part. The application simulates data transfer of the DVB-T system. Results of the simulated transmission, using developed application are presented in the last part. Namely dependence of the BER on the S/N ratio, using various coder settings, was examined. Maximal possible data rate was determined for these various setting. All obtained values are graphically represented.
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Polák, Ladislav. "Analýza a modelování přenosu signálu ve standardech DVB-H/SH." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-233589.
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Tato disertační práce se zabývá analýzou, simulací a měřením zpracování a přenosu signálů digitální televize pro příjem mobilního TV vysílání ve standardech DVB-H a DVB-SH. Tyto standardy vycházejí z předpokladu, že příjem signálu je charakterizován modely přenosových kanálů s vícecestným šířením. Tyto, tzv. únikové kanály, jsou charakterizovány hlavně zpožděním a ziskem jednotlivých cest. V závislosti na dalších parametrech (rychlost přijímače, Dopplerovské spektrum), je možné rozdělit únikové kanály do třech hlavních skupin: mobilní, přenosné a fixní. Dá se předpokládat, že v různých modelech kanálů bude přenášený signál různě ovlivněn. Proto je potřebné najít optimální parametry systémů (DVB-H/SH) pro kvalitní příjem vysílaných služeb mobilní televize, což je hlavním cílem této disertační práci. Pro tento účel byly vytvořeny dvě vhodné aplikace (jedna pro DVB-H a jedna pro DVB-SH) s GUI v prostředí MATLAB, které umožňují simulovat a analyzovat míru zkreslení signálu v případě mobilních, přenosných a fixních scénářů přenosu. Navíc, tyto aplikace obsahují i druhý samostatný simulátor pro nastavení a modifikaci parametrů jednotlivých přenosových cest. Díky tomu je možné zhodnotit vliv parametrů celého systému a kanálových modelů na dosaženou chybovost (BER a MER) a kvalitu přenosu. Ve všech přenosových scénářích (v závislosti na poměru C/N) byly získané, vyhodnocené a diskutované zkreslení signálů. Navíc, u standardu DVB-H, všechny získané výsledky ze simulací byly ověřeny měřením. Rozdíly mezi dosaženými výsledky (simulace a měření) byly rovněž podrobeny diskuzi. Tuto disertační práci je možné rozdělit do čtyř hlavních částí. První část disertační práce se zabývá rešerší současného vývoje v oblasti digitálního televizního vysílání na mobilní terminály ve standardech DVB-H/SH. Na konci této části jsou jasně popsány cíle této disertační práce. Druhá část práce je zaměřená na stručný popis blokového diagramu vysílačů v obou standardech DVB-H/SH. Dále jsou stručně popsány modely přenosových kanálů, které se používají pro modelování přenosu signálu. Stručný popis vytvořených aplikací, i s vývojovým diagramem, které jsou vhodné pro simulaci a analýzu přenosu v DVB-H/SH, jsou popsány v třetí části práce. Čtvrtá a nejdelší část této disertační práce se zabývá vyhodnocením získaných výsledků ze simulací a měření.
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Almeida, Karine Souza de. "An?lise da performance de sistemas de comunica??o sem fio baseados em OFDM utilizando um modelo de propaga??o na ?rea urbana de S?o Paulo - SP." Universidade Estadual de Feira de Santana, 2016. http://localhost:8080/tede/handle/tede/361.
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Funda??o de Amparo ? Pesquisa do Estado da Bahia - FAPEB
By using the Orthogonal Frequency Division Multiplexing (OFDM), it is possible to transmit by a channel a more robust signal and less susceptible to interferences. When such technique, based on orthogonal subcarriers, is combined with the use of propagation models, which are relevant tools for simulating the signal behavior in respect to environmental parameters and antenna configurations, it is feasible to have an evaluation about the performance of these systems, improving their project phase. Therefore, this work presents the use of OFDM technique applied to two propagation models: a two-ray geometric model and a microcellular model adapted to the Paulista Avenue, S?o Paulo, SP, having as objective the analysis of a mobile communication system through Bit Error Rate (BER). In the developed application using the MAtrix LABoratory (MATLAB) software, the mobile communication system based on OFDM admits several scenarios during the simulation, so that scenarios are related to positioning of the antennas, heights, type of modulation, size of the bit sequence to be sent, and others. The adopted OFDM architecture has been the IFFT/FFT and based on it, the system performs the transmission and reception of a bit set through a channel with interference by using different digital modulations, making appropriate comparisons.
Atrav?s da utiliza??o da t?cnica de Multiplexa??o por Divis?o de Frequ?ncias Ortogonais (OFDM, do ingl?s, Orthogonal Frequency Division Multiplexing), ? poss?vel transmitir por um canal um sinal mais robusto e menos propenso a interfer?ncias. Quando tal t?cnica, baseada na utiliza??o de subportadoras ortogonais, ? aliada ao uso de modelos de propaga??o, que s?o ferramentas relevantes para a simula??o do comportamento do sinal em rela??o aos par?metros do ambiente e as configura??es das antenas, ? poss?vel ter uma avalia??o a respeito do desempenho desses sistemas, melhorando a fase de projeto dos mesmos. Sendo assim, este trabalho apresenta o uso da t?cnica OFDM aplicada a dois modelos de propaga??o: um modelo geom?trico de dois raios e um modelo microcelular adaptado para a Avenida Paulista, S?o Paulo, SP, possuindo como objetivo a an?lise de um sistema de comunica??o m?vel atrav?s do c?lculo da Taxa de Erro de Bit (BER, do ingl?s, Bit Error Rate). Na aplica??o desenvolvida utilizando o software MATLAB (MATrix LABoratory), o sistema de comunica??o m?vel baseado em OFDM assume diversos cen?rios durante as simula??es, de forma que esses cen?rios s?o relacionados ao posicionamento das antenas, alturas, tipo de modula??o, tamanho da sequ?ncia de bits a ser enviada, entre outras. A arquitetura OFDM adotada foi a IFFT/FFT e baseado nela, o sistema realiza a transmiss?o e a recep??o de um conjunto de bits por um canal com interfer?ncias utilizando diferentes modula??es digitais, fazendo as devidas compara??es.
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Phillips, Kimberly Ann. "Probability Density Function Estimation Applied to Minimum Bit Error Rate Adaptive Filtering." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/33280.
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It is known that a matched filter is optimal for a signal corrupted by Gaussian noise. In a wireless environment, the received signal may be corrupted by Gaussian noise and a variety of other channel disturbances: cochannel interference, multiple access interference, large and small-scale fading, etc. Adaptive filtering is the usual approach to mitigating this channel distortion. Existing adaptive filtering techniques usually attempt to minimize the mean square error (MSE) of some aspect of the received signal, with respect to the desired aspect of that signal. Adaptive minimization of MSE does not always guarantee minimization of bit error rate (BER). The main focus of this research involves estimation of the probability density function (PDF) of the received signal; this PDF estimate is used to adaptively determine a solution that minimizes BER. To this end, a new adaptive procedure called the Minimum BER Estimation (MBE) algorithm has been developed. MBE shows improvement over the Least Mean Squares (LMS) algorithm for most simulations involving interference and in some multipath situations. Furthermore, the new algorithm is more robust than LMS to changes in algorithm parameters such as stepsize and window width.Master of Science
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Skrzypczak, Alexandre, Alain Thomas, and Guillaume Duponchel. "Paradigms Optimization for a C-Band COFDM Telemetry with High Bit Efficiency." International Foundation for Telemetering, 2013. http://hdl.handle.net/10150/579655.
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ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NVSystems using single carrier modulations for flight test transmissions perfectly fit noisy and time selective channels. However, the densification of the airport environment now makes the aero channel also frequency selective due to multiple reflections on surrounding buildings, especially while taxiing and taking off. Obviously, this has a direct consequence on hardware resources and user data rates. In such a context, COFDM represents an appealing solution thanks to its inherent robustness to multipath fading channels. But a direct application of an off-the-shelf COFDM standard is not straightforward as these standards are designed for specific channels whose characteristics are quite different from the aero one. That is why we made an experiment at Toulouse-Blagnac airport to jointly sound the channel and qualify a COFDM waveform. This paper then describes the construction of the waveform and the results of the channel sounding. From this, different standard paradigms are compared.
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Dang, Xiaoyu. "Performance Analysis of FQPSK and SOQPSK in Aeronautical Telemetry Frequency Selective Multipath Channel." International Foundation for Telemetering, 2004. http://hdl.handle.net/10150/605801.
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International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, CaliforniaThe impact of frequency selective multipath fading on the bit error rate performance of ARTM Tier-1 waveforms (FQPSK and SOQPSK) is derived and analyzed. In the presence of a strong specular reflection with relative magnitude |Γ1|, the ARTM Tier-1 waveforms suffer a loss in performance of (1 - |Γ1)^(-4√(|Γ1|)) for |Γ1| < 0:5 and a relatively high error floor at approximately 10^(-2) for |Γ1| ≥ 0.5. The ARTM Tier-1 waveforms possess twice the spectral efficiency of PCM/FM, but exhibit a greater loss and higher error floors than PCM/FM for the same multipath conditions and signal-to-noise ratio.
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Haghdad, Mehdi, and Kamilo Feher. "PERFORMANCE OF FQPSK TRANSCEIVERS IN A COMPLEX REAL-LIFE INTERFERENCE ENVIRONMENT." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606773.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaThe Bit Error Rate (BER) performance of FQPSK modulated signals in the presence of the Co-Channel Interference (CCI) and Additive White Gaussian Noise (AWGN) is evaluated and improved. A Non- Linearly Amplified (NLA) FQPSK modulated signal with the data rate of 1Mb/s and carrier frequency of 70 MHz is interfered with a sinusoidal signal at different frequencies. As the relative distance of the center frequency of the Co-channel interference (CCI) changes, different BER are obtained. The effect of the CCI decreases as the CCI center frequency moves away from the center of the modulated signal. In order to improve the BER in the presence of the CCI, a hard limited filter is added at the receiver input. The hard limited filter has a different amplification factor for different signal strength. As a result, the amplification factor for the CCI, which is normally a weaker signal, is smaller than the actual signal. This means that the signal is amplified more than the interference and as a result the CCI is suppressed and the BER rate improves. The results of both simulations and measurements are obtained for different CCI center frequencies, before and after the improvements.
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Law, Gene, and Don Whiteman. "IFM EFFECTS ON PCM/FM TELEMETRY SYSTEMS." International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/607378.
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International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, CaliforniaIncidental Frequency Modulation (IFM) products in telemetry transmitters can be a significant cause of bit errors in received Pulse Code Modulation/Frequency Modulation (PCM/FM) telemetry data. Range Commanders Council (RCC) and other documents give little or no guidance as to acceptable levels of IFM for telemetry applications. The expected higher vibration levels of future high velocity missile systems means that IFM levels are likely to be higher than previously encountered. This paper presents measured data on Bit Error Rate (BER) versus IFM levels at given Signal to Noise Ratios (SNR’s) for PCM/FM telemetry systems. The information presented can be utilized with BER versus SNR plots in the Telemetry Applications Handbook, RCC Document 119, to determine the additional link margin required to minimize IFM effects on telemetry data quality.
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Miniuk, Mary. "Channel Impulse Response and Its Relationship to Bit Error Rate at 28 GHz." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31002.
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Over the years, the Internet has become increasingly popular and people's dependence on it has increased dramatically. Whether it be to communicate to someone across the world, find blueprints, or check sports scores, the Internet has become a necessary resource for everyone. In emergency situations, this need increases further. After the terrorist attacks on the Pentagon, it took several days to restore communications. This is not an acceptable time frame when people's lives are at stake. Virginia Tech's Center for Wireless Telecommunication has developed a prototype of a rapidly deployable high bandwidth wireless communication system at 28 GHz (Local Multipoint Distribution Service frequency). This system provides a large bandwidth radio link to a disaster zone up to 5 km away and puts Ethernet speeds and 802.11 accesses to users within hours.
Because of the possible variability in locations that the system can be deployed, it is necessary to find the most useable channel at the site as quickly as possible. In addition to 28GHz radio links, the system also has a built-in channel sounder that measures and captures the channel impulse response of the current channel. Until now, there has been limited research on the relationship between the channel impulse response and the usability of the channel quantified using bit error rate.
This thesis examines several different channels captured by CWT's channel sounder and simulates the BER using Cadence's SPW with time-domain models of the channels. This thesis goes on further to show that BER greatly depends on the channel impulse response and the symbol rate.Master of Science
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Roy, Tamoghna. "Non-Wiener Characteristics of LMS Adaptive Equalizers: A Bit Error Rate Perspective." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/92869.
Full textAbstract:
Adaptive Least Mean Square (LMS) equalizers are widely used in digital communication systems primarily for their ease of implementation and lack of dependence on a priori knowledge of input signal statistics. LMS equalizers exhibit non-Wiener characteristics in the presence of a strong narrowband interference and can outperform the optimal Wiener equalizer in terms of both mean square error (MSE) and bit error rate (BER). There has been significant work in the past related to the analysis of the non-Wiener characteristics of the LMS equalizer, which includes the discovery of the shift in the mean of the LMS weights from the corresponding Wiener weights and the modeling of steady state MSE performance. BER performance is ultimately a more practically relevant metric than MSE for characterizing system performance. The present work focuses on modeling the steady state BER performance of the normalized LMS (NLMS) equalizer operating in the presence of a strong narrowband interference.
Initial observations showed that a 2 dB improvement in MSE may result in two orders of magnitude improvement in BER. However, some differences in the MSE and BER behavior of the NLMS equalizer were also seen, most notably the significant dependence (one order of magnitude variation) of the BER behavior on the interference frequency, a dependence not seen in MSE. Thus, MSE cannot be used as a predictor for the BER performance; the latter further motivates the pursuit of a separate BER model.
The primary contribution of this work is the derivation of the probability density of the output of the NLMS equalizer conditioned on a particular symbol having been transmitted, which can then be leveraged to predict its BER performance. The analysis of the NLMS equalizer, operating in a strong narrowband interference environment, resulted in a conditional probability density function in the form of a Gaussian Sum Mixture (GSM). Simulation results verify the efficacy of the GSM expression for a wide range of system parameters, such as signal-to-noise ratio (SNR), interference-to-signal (ISR) ratio, interference frequency, and step-sizes over the range of mean-square stable operation of NLMS. Additionally, a low complexity approximate version of the GSM model is also derived and can be used to give a conservative lower bound on BER performance.
A thorough analysis of the MSE and BER behavior of the Bi-scale NLMS equalizer (BNLMS), a variant of the NLMS equalizer, constitutes another important contribution of this work. Prior results indicated a 2 dB MSE improvement of BNLMS over NLMS in the presence of a strong narrowband interference. A closed form MSE model is derived for the BLMS algorithm. Additionally, BNLMS BER behavior was studied and showed the potential of two orders of magnitude improvement over NLMS. Analysis led to a BER model in the form of a GSM similar to the NLMS case but with different parameters. Simulation results verified that both models for MSE and BER provided accurate prediction of system performance for different combinations of SNR, ISR, interference frequency, and step-size.
An enhanced GSM (EGSM) model to predict the BER performance for the NLMS equalizer is also introduced, specifically to address certain cases (low ISR cases) where the original GSM expression (derived for high ISR) was less accurate. Simulation results show that the EGSM model is more accurate in the low ISR region than the GSM expression. For the situations where the derived GSM expression was accurate, the BER estimates provided by the heuristic EGSM model coincided with those computed from the GSM expression.
Finally, the two-interferer problem is introduced, where NLMS equalizer performance is studied in the presence of two narrowband interferers. Initial results show the presence of non-Wiener characteristics for the two-interferer case. Additionally, experimental results indicate that the BER performance of the NLMS equalizer operating in the presence of a single narrowband interferer may be improved by purposeful injection of a second narrowband interferer.PHD
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Colavito, Leonard R. "Evaluation of Space-Time Block Codes Under Controlled Fading Conditions Using Hardware Simulation." Diss., Temple University Libraries, 2010. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/66976.
Full textAbstract:
EngineeringPh.D.
Space time block codes (STBC) are a type of multiple input multiple output (MIMO) communications system that encode blocks of information into symbol sequences sent simultaneously from multiple antennas. MIMO communications systems have shown channel capacity improvement in multipath digital communications environments. The STBC class of MIMO communications systems can be easily decoded using linear combination and is resilient in the face of multipath channel effects. MIMO systems have traditionally been studied using theoretical analyses, simulations and real signal based experiments. Probabilistic models simulate channel effects as random variables, but are only estimates of actual conditions. Real signal experiments evaluate system performance under real-world conditions, but are not readily repeatable. Both modeling methods evaluate system performance in terms of the aggregate results. This dissertation research presents an approach that introduces controlled attenuation and delay to probabilistic channel models. This method allows the evaluation of MIMO system performance under specific channel conditions. The approach is demonstrated with a hardware accelerated STBC system model that is used to evaluate the performance of a MIMO system under controlled path conditions. The STBC system model utilizes a Xilinix® programmable gate array (PGA) device as a hardware accelerator. The model exploits the parallel processing capability of the PGA to simulate a nine path channel model and a three antenna rate ½ STBC. Novel implementations are developed for the additive white Gaussian noise (AWGN) sources and the linear MIMO decoding in PGA hardware. The model allows specification of overall noise and multipath fading effects for the channel as well as attenuation and phase delay for each channel path. Performance of the communications system is evaluated in terms of bit error rate (BER) versus signal-to-noise ratio (SNR). Hardware acceleration greatly reduces the time required to obtain simulation results. Reduced simulation time improves the use of the model by allowing evaluation of system performance under a greater number of conditions, greater performance curve resolution and evaluation at lower BER. The processing rate of the hardware accelerated model is compared to an equivalent software model. The model also provides an extensible platform for future research in communications theory.
Temple University--Theses
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Joch, Antonín. "Stanovení chybovosti optovláknového spoje." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217501.
Full textAbstract:
The master thesis discusses physical causes of light polarization and problems brought by nascence of Polarization Mode Dispersion (PMD). These problems occur especially by high speed systems on optical cable traces. The thesis deals with actuation of transmitted signal by influence of Inter Symbol Interference and it also deals with methods for its measuring and compensation. As a results of measurements are in text presented data provided by EXFO Electro-Optical Engineering Inc. Company. Significant part of the thesis focuses on optical link Bit Error Rate (BER) which is connected with Signal to Noise Ratio (SNR) and signal quality (Q-factor). Further on it is possible to find in text about so called eye diagram which is display mode that shows influence of communication channel on shape of the transmitted signal. To this diagram is related another one called constellation diagram which describes modulation mode and makes it possible to map dispersion of signal points around their nominal values. In connection with so called trajectory it makes vector diagram. Practical part includes depiction of these diagrams in MATLAB development environment.