Mestrado em Engenharia Elétrica e da Computação (EMC)
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Navegando Mestrado em Engenharia Elétrica e da Computação (EMC) por Assunto "5G"
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Item Propostas de um modelo para o tráfego de redes de comunicações e de funções de janela para o filtro FIR utilizado na tecnologia f-OFDM(Universidade Federal de Goiás, 2019-10-31) Silva, Maykon Renan Pereira da; Rocha, Flávio Geraldo Coelho; http://lattes.cnpq.br/5583470206347446; Vieira, Flávio Henrique Teles; Lemos, Rodrigo Pinto; Santos Junior, Josemar Alves dosIn this work, in order to model the communication network traffic processes, we propose an efficient multifractal model that takes into account less parameters than other models present in the literature. The MEV (Exponential Modeling for Multiplier Variance) model is based on a multiplicative cascade in the wavelet domain capable of synthesizing traffic samples from communications networks that have characteristics such as self-similarity and wide Multifractal Spectrum Width (MSW). For this purpose, in the MEV model, the energy decay of the wavelet coefficients uses a parametric modeling based on an exponential distribution for the variance of multipliers along the cascade stages. The performance of the MEV model in describing the characteristics of network traffic is compared to other models in the literature. For this, real network traffic traces of communication networks are used. In addition, a class of adjustable Nakagami distribution based window functions is proposed for the construction of the windowed-sinc digital filter used by f-OFDM technology. To this end, the filter performance in terms of spectral efficiency and out-of-band emission (OOBE) is compared by analyzing power spectral density (PSD) results. In addition, the FIR filter processing time is verified using different window functions and the bit error rate (BER) in the data transmission process. The results obtained using f-OFDM are compared with those obtained through the unfiltered OFDM technology and also with the FBMC and UFMC technologies. The results obtained show that f-OFDM technology (especially using Nakagami windows) is a candidate for applications in future generations of mobile communication systems, as compared to OFDM technology, it maintains its advantages, for example ISI, while reducing one of its disadvantages, out-of-band emissions (OOBE).Item Avaliação comparativa de modulações candidatas às redes 5G baseadas em LTE e escalonamento de recursos considerando fila e qualidade de canal(Universidade Federal de Goiás, 2018-07-04) Souza, Dalton Foltran de; Vieira, Flávio Henrique Teles; http://lattes.cnpq.br/0920629723928382; Vieira, Flávio Henrique Teles; Borges, Vinicius da Cunha Martins; Rocha, Flávio Geraldo Coelho; Cardoso, Kleber VieiraWith the development of the next generation of mobile communications systems for 5G, several technologies are being studied aiming to reach the new requirements in new application scenarios. Among them, is the use of new modulations with higher spectral efficiency in substitution of OFDM, such as F-OFDM and UFMC, and also the scheduling algorithms which are in charge of sharing resources between users. In this work, we evaluated the application of F-OFDM and UFMC, 5G modulations candidates, on downlink LTE compared with OFDM and evaluated the schedulers Round Robin, QoS Guaranteed and PSO dealing with additional resources provided by the tested modulations. For that, we compared performance considering parameters like fairness, latency, throughput and spectral efficiency. The results showed that the downlink LTE improved performance in all evaluated parameters with UFMC modulation. In fact, there were a performance improvement in all schedulers evaluated. For example, PSO based scheduler improved latency and throughput while QoS Guaranteed reached the lowest loss, as the highest fairness were reached by QoS Guaranteed and Round Robin. Also, we propose a scheduling algorithm that takes into account the queue size in the user buffer and channel quality to maximize throughput and fairness in the LTE downlink network. The metrics evaluated were transmission efficiency, throughput, fairness, delay and losses. The proposed algorithm achieved better results for all evaluated metrics.