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Increasingly, wireless subscribers are demanding reliable data capabilities from wireless networks. The ability of wireless network engineers and Information Technology (IT) professionals to rapidly design, deploy, and maintain wireless communication systems that can provide strong, reliable data service is severely hampered by a lack of adequate systems and methods for simulating the performance of such networks a priori. Unlike older generation wireless systems that could be readily deployed on the basis of strong received signal strength and simple circuit-switched channel allocation protocols, modern and emerging wireless data networks are more noise and interference limited and rely on packet-based protocols. A heavier emphasis is needed on predicting and simulating throughput, bit error rate, frame error rate, user priority classes, and overall network capacity. This research provides wireless network engineers and IT professionals with a comprehensive system and method for the simulation and design of wireless communication systems that combines site-specific databases, equipment-specific distribution system modeling, and advanced ray tracing propagation analysis to directly predict throughput, frame error rate (FER), and other critical performance parameters for emerging wireless data networks. / Ph. D.

Le contexte de cette thèse est celui des communications optiques sans fil pour des applications en environnements indoor. Pour discuter des performances d'une liaison optique sans fil, il est nécessaire d'établir une étude caractéristique du comportement du canal de propagation. Cette étude passe par l'étape de la mesure ou de l'estimation par la simulation de la réponse impulsionnelle. Après avoir décrit la composition d'une liaison et passé en revue les méthodes de simulation existantes, nous présentons nos algorithmes de simulation dans des environnements réalistes, en nous intéressant à leurs performances en termes de précision et de temps de calcul. Ces méthodes sont basées sur la résolution des équations de transport de la lumière par du lancer de rayons associées aux méthodes d'intégration stochastique de Monte Carlo. La version classique de ces méthodes est à la base de trois algorithmes de simulations proposés. En utilisant une optimisation par des chaînes de Markov, nous présentons ensuite deux autres algorithmes. Un bilan des performances de ces algorithmes est établi dans des scénarios mono et multi-antennes. Finalement, nous appliquons nos algorithmes pour caractériser l'impact de l'environnement de simulation sur les performances d'une liaison de communication par lumière visible, à savoir les modèles d'émetteurs, les matériaux des surfaces, l'obstruction du corps de l'utilisateur et sa mobilité, et la géométrie de la scène de simulation. / The context of this PhD thesis falls within the scope of optical wireless communications for applications in indoor environments. To discuss the performance of an optical wireless link, it is necessary to establish a characteristic study of the behavior of the optical wave propagation channel. This study can be realized by measurement or by the simulation of the channel impulse response. After describing the composition of an optical wireless link and reviewing existing simulation methods, we present our new simulation algorithms channel in realistic environments by focusing on their performances in terms of accuracy and their complexity in terms of computation time. These methods are based on solving the light transport equations by ray-tracing techniques associated with stochastic Monte Carlo integration methods. The classical version of these methods is the basis of three proposed simulation algorithms. By applying an optimization using Markov Chain, we present two new algorithms. A performance assessment of our simulation algorithms is established in mono and multi-antenna scenarios of our simulation algorithms. Finally, we present the application of these algorithms for characterizing the impact of the simulation environment on the performances of a visible light communication link. We particularly focus on the transmitter models, surface coating materials, obstruction of the user's body and its mobility, and the geometry of the simulation scene.

Submitted by Patrick Sales (patrick_laser@yahoo.com.br) on 2015-12-18T18:01:09Z No. of bitstreams: 1 dissertação patrick sales versão deposito.pdf: 1192037 bytes, checksum: 1e8db5024665664af6fc9e5263ffc78a (MD5) / Approved for entry into archive by ÁUREA CORRÊA DA FONSECA CORRÊA DA FONSECA (aurea.fonseca@fgv.br) on 2015-12-18T19:28:51Z (GMT) No. of bitstreams: 1 dissertação patrick sales versão deposito.pdf: 1192037 bytes, checksum: 1e8db5024665664af6fc9e5263ffc78a (MD5) / Approved for entry into archive by Marcia Bacha (marcia.bacha@fgv.br) on 2015-12-21T18:15:25Z (GMT) No. of bitstreams: 1 dissertação patrick sales versão deposito.pdf: 1192037 bytes, checksum: 1e8db5024665664af6fc9e5263ffc78a (MD5) / Made available in DSpace on 2015-12-21T18:15:40Z (GMT). No. of bitstreams: 1 dissertação patrick sales versão deposito.pdf: 1192037 bytes, checksum: 1e8db5024665664af6fc9e5263ffc78a (MD5) Previous issue date: 2015-11-26 / A modernização da Marinha do Brasil se faz necessária em face de fatores relacionados à obsolescência dos meios, incremento tecnológico e outros incentivos de ordem doméstica e internacional. No caso brasileiro, apesar de haverem diversos programas de reaparelhamento desde a proclamação da república, os programas de maior envergadura e que geraram resultados importantes ocorreram em 1910, 1977 e 2007. O Reaparelhamento da Marinha do Brasil responde principalmente a incentivos de ordem sistêmica e doméstica. A sua efetividade é o principal objetivo de um programa de incremento material, e muito mais do que orientação à defesa da pátria, os objetivos expressos na grande estratégia de um país devem preceder a decisão de repotencialização da Força. O trabalho utiliza a metodologia histórico comparativa, por meio do método denominado Process Tracing. Essa incipiente metodologia permite verificar as evidências ao longo de processos e verificar a hierarquização de cada fator por meio de testes empíricos baseados na minuciosa descrição histórica dos casos. As teorias realistas buscam explicações para o comportamento dos países em relação ao Sistema Internacional. O ambiente anárquico em que se encontram os países definem suas preferências, mas o aspecto doméstico responde fortemente a esses incentivos sistêmicos e justifica as diferentes conduções de políticas externas em ambiente similar. A teoria neoclássica considera os fatores domésticos como intervenientes neste processo. Por meio do modelo desenvolvido por Schweller (2006), este trabalho verificou que o aspecto sistêmico é determinante para o reaparelhamento da Marinha, e no âmbito doméstico o consenso e coesão das elites são necessárias, entretanto a coesão social passou de coadjuvante a uma das condições necessárias a partir do início do século XXI no processo de reaparelhamento. / The Brazilian Navy’s modernization is needed in the face of factors related to obsolescence, technological advances and other domestic and international incentives. In Brazil, although there are several refit programs since beginning of Republic, the biggest programs and whose generated important results occurred in: 1910, 1977 and 2007. The Modernization of the Brazilian Navy responds mainly to systemic and domestic incentive. Its effectiveness is the main goal of a material increase program, and more than orientation to country’s defense, the objectives expressed in the grand strategy should precede the Armed Forces re-powering decision The paper uses historical comparative method, using the method called Process Tracing. This incipient methodology for verifying the evidence over processes and verify each factor’s hierarchy through empirical tests based on thorough historical description of cases. Realistic theories seek explanations for countries’ behavior on International System. The anarchic environment in which they are, define their preferences, but the domestic aspect responds strongly to these systemic incentives and justifies the different conduction of foreign policies in a similar environment. The neoclassical theory considers the domestic factors as stakeholders in this process. Through the model developed by Schweller (2006), this study found that the systemic aspect is crucial to the reequipping of the Navy, and domestic consensus and cohesion of the elites are necessary, however social cohesion went from supporting one of the conditions necessary from the beginning of the XXI century in the repowering process.

Subject of this thesis is acceleration of the photon mapping method on a graphic card. The photon mapping is a method for computing almost realistic global illumination of the scene. The computation itself is relatively time-consuming, so the acceleration of it is a hot issue in the field of computer graphics. The photon mapping is described in detail from photon tracing to rendering of the scene. The thesis is then focused on spatial subdivision structures, especially to the uniform grid. The design and the implementation of the application computing the photon mapping on GPU, which is achieved by OpenGL and CUDA interoperability, is described in the next part of the thesis. Lastly, the application is tested properly. The achieved results are reviewed in the conclusion of the thesis.

Master thesis is dealing with design and implementation of ray-tracing and path-tracing using IPP library. Theoretical part discusses current trends in acceleration of selected algorithms and also possibilities of parallelization. Design of ray-tracing and path-tracing algorithm and form of parallelization are described in proposal. This part also discusses implementation of adaptive sampling and importance sampling with Monte Carlo method to accelerate path-tracing algorithm. Next part is dealing with particular steps in implementation of selected rendering methods regarding IPP library. Implementation of network interface using Boost library is also discussed. At the end, implemented methods are subjected to performance and quality test. Final product of this thesis is server aplication capable of handling multiple connections which provides visualisation and client application which implements ray-tracing and path-tracing.