DVBS2X standard FPGA implementation of LLR, physical layer de-scrambling and symbol timing synchronization (STR) blocks for satellite applications

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade UnB Gama, 2019.Dentre o paradigma da comunicação digital, existe o contexto de rádio definido por software, que pode trazer muitas vantages sobre os modelos de radio classicos não reconfiguráveis, por exemplo, o aumento na flexibilidade, que como consequencia traz uma maior facilidade em manutenção e conteção de erros de projeto. Uma estrutura que adiciona à morfologia se aplicando em um conjunto volumoso de contextos e mostrando características unicas de aplicação são os chips field programmable gate array (FPGA). Neste texto foram projetados três blocos do protocolo de comunicação DVBS2X para um SDR em que a aplicação principal é a comunicação por satélite em banda Ku. Os blocos são: Symbol timing synchronization, que lida com a correspondência o tempo de amostragem entre o sinal em quadratura transmitido e o recebido, baseando-se em um algoritmo closed loop non data-aided Gardner Timing Error Detection. O bloco Log Likelihood Ratio, que é um detector maximum à posteriori que estima o símbolo transmitido baseando-se nos símbolos recebidos corrompidos pelo canal AWGN. Symbol Physical Layer De-scrambling, que faz a operação oposto do bloco textitPhysical Layer Scrambling definido para o transmissor pelo padrão DVBS2Xm multiplicando o símbolo recebido por um número complexo definido por uma golden sequence, implemenetando dois linear feedback shift registers na FPGA. Os resultados foram favoráveis com arquiteturas de hardware escolhidas e projetadas, cada bloco foi projetado com uma metodologia Top-down e validado com arquivos vetores codificados em linguagem de alto nível como PYTHON e MATLAB. Este texto propôs e implementou três soluções em hardware viáveis com complexidade de implementação razoáveis, baseando-se sempre no protocol padrão e comparando com outros exemplos da literatura acadêmica.Within the paradigm of digital communication, there exist the context of software-defined radios, in which many advantages can be found over classical non-reconfigurable radios, for example, the rise in flexibility, that as consequence causes ease in maintenance and project error repair. A structure that adds to this scheme applying itself in a plethora of contexts and showing unique application characteristics is the Field Programmable Gate Array (FPGA) chips. In this text, it was projected three blocks from the DVBS2X standard for an SDR with the main application objective being satellite communication in Ku band. The blocks are: Symbol timing synchronization, that deals with the matching between the transmitted quadrature waveform sampling time and the receiver sampling time, based on a close-loop non-data aided Gardner Timing Error Detection algorithm. Log Likelihood Ratio block, that is a maximum à posteriori symbol estimator based on the received symbols corrupted by the AWGN channel. Symbol Physical Layer Descrambling, that makes the opposite operation from the Physical Layer descrambling defined for the transmitter in the DVBS2X protocol, multiplying the received symbol by a complex number defined with a golden sequence, implemented with two linear feedback shift registers in FPGA. The results were favorable with hardware architectures chosen and projected, each block was design with a Top-down design methodology and validated with vector files coded in high-level languages such as PYTHON and MATLAB. This text proposed and implemented three hardware solutions with synthesizable hardware complexity, based on the DVBS2X standard

Enlace de retorno satelital DVB-RCS2 : modelagem de fila e otimização de alocação de recursos baseada em teoria dos jogos

Tese (doutorado) — Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2022.É esperado que satélites tenham um papel fundamental no futuro dos sistemas de comunicação, integrando-se às infraestruturas terrestres. Esta dissertação de mestrado propõe três contribuições principais: primeiramente, se apresenta um arcabouço de simulação capaz de prover detalhes da performance de redes de comunicação satelital em cenários realistas. Este arcabouço aplica uma metodologia orientada a eventos, modelando a rede de comunicação como um sistema baseado em eventos discretos (DES), focando no enlace de retorno do protocolo DVB-RCS2. Três diferentes cenários simulados demonstram os possíveis usos das saídas do simulador para entender o comportamento dinâmico da rede e alcançar um ponto ótimo de operação do sistema. Cada cenário explora uma característica diferente do simulador, enquanto cobre um grande território de usuários, que em nosso caso estudo o país de escolha foi o Brasil. Em um segundo tópico, este trabalho introduz um novo algoritmo modificado do método de alocação de timeslots baseado em teoria dos jogos, aplicando-se no protocolo DVB-RCS2. Este procedimento considera a eficiência espectral do terminal como um parâmetro de peso para o problema de otimização convexa resultante da solução da barganha de Nash. Este novo método garante o cumprimento dos requisitos de Qualidade de Serviço (QoS) enquanto provê uma medida de justiça maior; os resultados mostram uma melhoria de 5% na medida de justiça, com uma diminuição de 75% no desvio padrão de justiça entre os quadros, também alcançando um aumento de 12% na satisfação individual média pela alocação de capacidade aos terminais. Por final, apresentamos uma modelagem alternativa para o enlace de retorno do DVB-RCS2 usando cadeias de Markov, predizendo parâmetros tradicionais de fila como a intensidade de tráfego, tempo médio de espera, dentre outros. Utilizamos dados coletados de uma série de simulações usando o arcabouço orientado a eventos para validar o modelo de filas como uma aproximação numérica útil para o cenário real de aplicação. Nós apresentamos o algoritmo de alocação de controle do parâmetro alfa (GTAC) que consegue controlar o tempo médio de espera de um RCST na fila, respeitando um limiar de tempo enquanto otimiza a taxa média média de transmissão de dados dos terminais.Satellite networks are expected to play a vital role in future communication systems, with complex features and seamless integration with ground-based infrastructure. This dissertation proposes three main contributions: firstly, it presents a novel simulation framework capable of providing a detailed assessment of a satellite communication’s network performance in realistic scenarios, employing an event-driven methodology and modeling the communications network as a DES (discrete event system). This work focuses on the return link of the Digital Video Broadcast Return Channel via Satellite (DVB-RCS2) standard. Three different scenarios demonstrate possible uses of the simulator’s output to understand the network’s dynamic behavior and achievable optimal system operation. Each scenario explores a different feature of the simulator. The simulated range covers a large territory with thousands of users, which in our case study was the country of Brazil. In the second theme, this work introduces a novel algorithm modification for the conventional game theory-based time slot assignment method, applying it to the DVB-RCS system. This procedure considers the spectral efficiency as a weighting parameter. We use it as an input for the resulting convex optimization problem of the Nash Bargaining Solution. This approach guarantees the fulfillment of Quality of Service (QoS) constraints while maintaining a higher fairness measure; results show a 5% improvement in fairness, with a 73% decrease in the standard deviation of fairness between frames, while also managing to reach a 12.5% increase in average normalized terminal BTU allocation satisfaction. Lastly, we present an alternative queuing model analysis for the DVB-RCS2 return link using Markov chains, developed to predict traditional queue parameters such as traffic intensity, average queue size, average waiting time, among others. We used data gathered from a series of simulations using the DES framework to validate this queuing model as a useful numerical approximation to the real application scenario, and, by the end of the scope, we present the alpha allocation algorithm (GTAC) that can maintain the average waiting time of a terminal in the queue to a threshold while optimizing the average terminal throughput

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Osteopontin is upregulated in human and murine acute schistosomiasis mansoni

Background Symptomatic acute schistosomiasis mansoni is a systemic hypersensitivity reaction against the migrating schistosomula and mature eggs after a primary infection. The mechanisms involved in the pathogenesis of acute schistosomiasis are not fully elucidated. Osteopontin has been implicated in granulomatous reactions and in acute hepatic injury. Our aims were to evaluate if osteopontin plays a role in acute Schistosoma mansoni infection in both human and experimentally infected mice and if circulating OPN levels could be a novel biomarker of this infection. Methodology/Principal Findings Serum/plasma osteopontin levels were measured by ELISA in patients with acute (n = 28), hepatointestinal (n = 26), hepatosplenic (n = 39) schistosomiasis and in uninfected controls (n = 21). Liver osteopontin was assessed by immunohistochemistry in needle biopsies of 5 patients. Sera and hepatic osteopontin were quantified in the murine model of schistosomiasis mansoni during acute (7 and 8 weeks post infection, n = 10) and chronic (30 weeks post infection, n = 8) phase. Circulating osteopontin levels are increased in patients with acute schistosomiasis (p = 0.0001). The highest levels of OPN were observed during the peak of clinical symptoms (7-11 weeks post infection), returning to baseline level once the granulomas were modulated (>12 weeks post infection). The plasma levels in acute schistosomiasis were even higher than in hepatosplenic patients. The murine model mirrored the human disease. Macrophages were the major source of OPN in human and murine acute schistosomiasis, while the ductular reaction maintains OPN production in hepatosplenic disease. Soluble egg antigens from S. mansoni induced OPN expression in primary human kupffer cells. Conclusions/Significance S. mansoni egg antigens induce the production of OPN by macrophages in the necroticexudative granulomas characteristic of acute schistosomiasis mansoni. Circulating OPN levels are upregulated in human and murine acute schistosomiasis and could be a noninvasive biomarker of this form of disease

Osteopontin Is Upregulated in Human and Murine Acute Schistosomiasis Mansoni

<div><p>Background</p><p>Symptomatic acute schistosomiasis mansoni is a systemic hypersensitivity reaction against the migrating schistosomula and mature eggs after a primary infection. The mechanisms involved in the pathogenesis of acute schistosomiasis are not fully elucidated. Osteopontin has been implicated in granulomatous reactions and in acute hepatic injury. Our aims were to evaluate if osteopontin plays a role in acute <i>Schistosoma mansoni</i> infection in both human and experimentally infected mice and if circulating OPN levels could be a novel biomarker of this infection.</p><p>Methodology/Principal Findings</p><p>Serum/plasma osteopontin levels were measured by ELISA in patients with acute (n = 28), hepatointestinal (n = 26), hepatosplenic (n = 39) schistosomiasis and in uninfected controls (n = 21). Liver osteopontin was assessed by immunohistochemistry in needle biopsies of 5 patients. Sera and hepatic osteopontin were quantified in the murine model of schistosomiasis mansoni during acute (7 and 8 weeks post infection, n = 10) and chronic (30 weeks post infection, n = 8) phase. Circulating osteopontin levels are increased in patients with acute schistosomiasis (p = 0.0001). The highest levels of OPN were observed during the peak of clinical symptoms (7–11 weeks post infection), returning to baseline level once the granulomas were modulated (>12 weeks post infection). The plasma levels in acute schistosomiasis were even higher than in hepatosplenic patients. The murine model mirrored the human disease. Macrophages were the major source of OPN in human and murine acute schistosomiasis, while the ductular reaction maintains OPN production in hepatosplenic disease. Soluble egg antigens from <i>S</i>. <i>mansoni</i> induced OPN expression in primary human kupffer cells.</p><p>Conclusions/Significance</p><p><i>S</i>. <i>mansoni</i> egg antigens induce the production of OPN by macrophages in the necrotic-exudative granulomas characteristic of acute schistosomiasis mansoni. Circulating OPN levels are upregulated in human and murine acute schistosomiasis and could be a non-invasive biomarker of this form of disease.</p></div

Sera and hepatic osteopontin are upregulated in human acute schistosomiasis mansoni.

<p>A) ELISA for osteopontin in the plasma of uninfected controls (NI, n = 21) and schistosomiasis patients with Acute (n = 3), hepatointestinal (n = 26) and hapatosplenic (n = 39) forms of disease. B) ELISA for osteopontin in the serum of uninfected controls (n = 21) and patients with acute schistosomiasis mansoni (n = 28). C) ELISA for osteopontin in the serum of uninfected controls (NI, n = 21) and patients with acute schistosomiasis mansoni (n = 28) grouped by weeks post infection. Medians are displayed; Mann-Whitney U test: #p<0.05, ##p<0.01, ###p<0.001, ####p<0.0001 vs uninfected controls; *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. D) Immunohistochemistry for osteopontin in liver needle biopsy fragment of a representative subject with acute schistosomiasis mansoni (10 weeks post infection). Final magnification 100x, 200x and 400x.</p

Soluble egg antigens induce Osteopontin expression in primary human Kupffer cells.

<p>A) Double Immunohistochemistry for osteopontin (OPN,brown) and CD68 (macrophage marker, green) in liver needle biopsy fragment of a representative subject with acute schistosomiasis mansoni (10 weeks post infection, same case depicted in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0005057#pntd.0005057.g001" target="_blank">Fig 1D</a>) demonstrating that macrophages express osteopontin in human acute schistosomiasis mansoni. The rectangle highlights the magnified area shown on the 2 pannels on the right. Final magnification 100x (left), 400x (upper right) and 600x (lower right). B) Osteopontin mRNA expression (fold change) in primary human Kupffer cells incubated with 10 μg/ml SEA or 0.0001 μg/ml LPS (lipopolysaccharide; control, same amount of endotoxin present in the SEA preparation) after 3 hours of incubation. Mean±SEM are displayed, Student’s t test: *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001.</p

Sera and hepatic osteopontin are upregulated in the acute phase of murine schistosomiasis mansoni.

<p>A) ELISA for osteopontin in the serum of uninfected (NI) mice and mice experimentally infected with <i>S</i>. <i>mansoni</i> in the acute (6,7 and 8 weeks post infection) and chronic phase (30 weeks post infection). Medians are displayed, Mann-Whitney U test: *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. B) Serum osteopontin ELISA of uninfected controls and infected mice grouped by weeks post infection. Medians are displayed, Mann-Whitney U test: #p<0.05, ##p<0.01, ###p<0.001, ####p<0.0001 vs non-infected; *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. C) Immunohistochemistry for osteopontin in representative liver section of uninfected mice (left), infected mice in the acute phase (middle) and infected mice in the chronic phase (right). Final magnification 200x. D) Morphometry of the immunohistochemistry for osteopontin. Means are displayed; Student’s t test: #p<0.05, ##p<0.01, ###p<0.001, ####p<0.0001 vs non-infected; *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. E) Number of osteopontin positive bile ducts per 200x power field. Means are displayed; Student’s t test: *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001.</p