https://hdl.handle.net/ripcmb/30293 2026-04-01T01:23:19Z https://hdl.handle.net/20.500.14867/848033 Título: Estimação de canal usando RIS híbrida e OMP com refinamentos sucessivos Autor(es): Martiniano, Luiz Henrique de Oliveira; Guerra, David W. M.; Abrão, Taufik; Panazio, Cristiano Magalhães Abstract: Reconfigurable Intelligent Surfaces (RIS) are a promising solution for increasing the data rate and coverage in 6G systems. The use of active elements in a RIS (hybrid RIS) allows for reducing the length of pilot sequences and the complexity of channel estimation. In this context, it is proposed to use successive rotations in a technique based on the Orthogonal Matching Pursuit (OMP) algorithm, which performs channel estimation by treating it as a compressive sensing (CS) problem. Simulations show that the proposed technique achieves equal or superior performance with lower complexity compared to other approaches. Descrição: Superfícies Inteligentes Reconfiguráveis (RIS - Re- configurable Intelligent Surface) são uma solução promissora para aumentar a taxa e a cobertura em sistemas 6G. O uso de elementos ativos na RIS, gerando uma RIS híbrida, permite reduzir o comprimento das sequências piloto e a complexidade da estimação de canal. Neste contexto, propõe-se utilizar sucessivas rotações em uma técnica baseada no algoritmo Orthogonal Matching Pursuit (OMP), que resolve a estimação do canal tratando-o como um problema do tipo amostragem compressiva (CS - Compressive Sensing). Simulações mostram que a técnica proposta alcança desempenho igual ou superior com menor complexidade em relação a outras abordagens. Tipo: conferenceObject 2025-01-01T00:00:00Z https://hdl.handle.net/ripcmb/846901 Título: Estudo da Influência do Movimento de Afundamento de um Navio em um Enlace de Comunicações FSO Autor(es): Gurgel Júnior, Airton Fernandes; Azzolin, Claisso Pires; Carneiro, Vítor Gouvêa Andrezo; Castillo, Claudio Alexis Rodríguez Descrição: This article analyzes the performance of a free- space optic (FSO) communication link established between a maritime platform and a land base. In this analysis, the effects of radial misalignment of the transmitted optical beam, caused by the sinking movement of a ship, are considered. In this sense, the availability of the FSO link was simulated, for a hull shape similar to a Brazilian Navy ship, based on geometric attenuation, considering a conical beam model with uniform power distribution. Tipo: article 2024-01-01T00:00:00Z https://hdl.handle.net/ripcmb/846900 Título: Marcum Q -function as an analytical solution for misaligned Gaussian beams Autor(es): Azzolin, Claisso; Gurgel Júnior, Airton Fernandes; Carneiro, Vítor Gouvêa Andrezo Descrição: A point-to-point optical link is usually based on a laser beam, where the most common propagation model is the Gaussian beam type. Due to its directional characteristics, minor alignment errors can cause considerable attenuation. The calculation of the misalignment losses involves solving an integral of a Gaussian beam translated over a receiver’s effective surface, leading to a more accurate link budget. Our work proposes a closed-form expression for calculating the geometric and misalignment attenuation, caused by translational movements in circular Gaussian beams. © 2021 Society of Photo-Optical Instrumentation Engineers (SPIE) Tipo: article 2024-01-01T00:00:00Z https://hdl.handle.net/ripcmb/846899 Título: Statistical modeling of atmospheric turbulence based on a low-cost experimental setup for measuring C2 n over water Autor(es): Carvalho, Carvalho; Azzolin, Claisso; Gurgel Júnior, Airton Fernandes; Carneiro, Vítor; Giraldi, Maria Thereza Descrição: Theperformanceofcommunicationsystemsbasedonfree-spaceopticallinksdependsonexternalfactorssuchas weather conditions. Among many atmospheric factors, turbulence can be the greatest challenge to performance. The characterization of atmospheric turbulence usually involves expensive equipment known as a scintillometer. Thisworkpresentsalow-costexperimentalsetupformeasuringtherefractiveindexstructureconstantoverwater, which results in a statistical model based on weather conditions. The turbulence variations with air and water temperature,relativehumidity,pressure,dewpoint,anddifferentwatercoursewidthsareanalyzedfortheproposed scenario. Tipo: article 2024-01-01T00:00:00Z