Aplicação do algoritmo MSCL com subparticionamento por múltiplas rotas

Clayton J. N Lira, Raul C. Almeida Jr, Daniel Chaves

DOI: 10.14209/sbrt.2021.1570734154

Keywords: Split Spectrum Roteamento Alocação de espectro

Abstract

Due to its ability to provide resources adapted according to demand, Elastic Optical Networks have emerged as a very promising network option. Such networks have been the subject of several studies in order to present techniques and heuristics with the ability to explore their benefits and also find solutions to their problems, among them the routing and spectrum assignment. This work addresses the use of the Split Spectrum (SS) technique applied in the routing process, analyzing its performance in different scenarios and combining with the MSCL spectrum assignment algorithm. It is shown that, combining different forms of spectrum division with the spectrum allocation that generates the least loss of capacity, one can find a technique that provides better results when compared to the traditional allocation of spectrum and its classic form of division.

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An Algorithm for Finding an Approximate Reliability Sequence for Polar Codes on the BEC

Saeid Ghasemi, Bartolomeu F. Uchôa-Filho

DOI: 10.14209/sbrt.2021.1570734156

Keywords: Polar codes reliability sequence binary erasure channel

Abstract

One of the most important parts of encoding and decoding in polar codes is finding the bit-channel reliability sequence, i.e., the positions of frozen bits and data bits, which has a great effect on the error correction performance. In this paper, we present an algorithm with linear complexity for determining an approximate reliability sequence in small disagreement with the true reliability sequence on the binary erasure channel (BEC).

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Joint Beamforming Design for IRS-Assisted Beyond 5G Wireless Networks

Yuri Sales Ribeiro, Francisco Hugo Costa Neto, André de Almeida, Paulo R. B. Gomes

DOI: 10.14209/sbrt.2021.1570734157

Keywords: Intelligent reflecting surface beamforming spectral efficiency energy efficiency

Abstract

Intelligent reflecting surface (IRS) has emerged as a promising technology to enhance wireless communications by smartly shaping the radio propagation environment with reduced hardware and energy costs. In this paper, we integrate the IRS to a multiple-input single-output (MISO) fifth generation (5G) system via the joint optimization of the IRS reflecting coefficients and the transmit beamforming at the base station (BS) to maximize the spectral efficiency in an urban micro (UMi) propagation environment. Simulation results indicate that IRS successfully enhances the performance of the wireless network in terms of spectral and energy efficiencies compared with traditional transmit beamforming and relay-assisted systems.

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On the Secrecy Performance of a Hybrid RF/VLC System

Isabella W. G. da Silva, Diana Pamela Moya Osorio, Edgar Eduardo Benitez Olivo, Iqrar Ahmed, Marcos Katz

DOI: 10.14209/sbrt.2021.1570734160

Keywords: Hybrid RF/VLC physical layer security secrecy outage probability Visible light communications

Abstract

This paper evaluates the secrecy outage probability of a hybrid radio frequency (RF) and visible light communication (VLC) network in the presence of an eavesdropper. We assume that data is transmitted over the RF and VLC links following a proposed multiplexing scheme in which the data sent by the source is split with a certain allocation ratio. Furthermore, the legitimate and eavesdropper users are assumed to have multihoming capabilities, so that they are able to receive data from both RF and VLC access points, simultaneously. We derive integral-form exact expression, as well as a closed-form asymptotic expression for the secrecy outage probability and validate them via Monte Carlo simulations. Our results show that multiplexing the information signal by both links leads to an enhancement of the secrecy performance since it opportunistically takes advantages of the best characteristics of both domains.

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Algoritmo de Roteamento para Otimização de Desempenho de uma Rede Óptica Elástica

Jefferson Leite, Igor dos Santos, Helder A. Pereira, Raul C. Almeida Jr

DOI: 10.14209/sbrt.2021.1570734167

Keywords: Algoritmo de Roteamento Penalidade Física Rede Óptica Elástica Relação Sinal-Ruído Óptica

Abstract

Basically, when considering dynamic traffic and topologies with a high number of nodes, the Dijkstra algorithm is used and its cost function is modified in order to optimize the performance of optical networks. In this context, the contribution of this paper is to adapt a routing algorithm available in the wavelength division multiplexing optical networks for the scenario of elastic optical networks and to investigate its performance considering some routing algorithms. Aspects of the physical layer are considered, such as gains and losses along the devices, in addition to the amplified spontaneous emission noise generated in optical amplifiers.

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Channel Estimation and Joint Beamforming Design for Multi-IRS MIMO systems

Kenneth Brenner Benício, Bruno Sokal, André de Almeida

DOI: 10.14209/sbrt.2021.1570734169

Keywords: Intelligent reflecting surface MIMO systems channel estimation beamforming design

Abstract

In this paper, we propose a channel estimation and joint beamforming design method for multi-IRS multiple-input and multiple-output (MIMO) systems. We investigate the scenario where multiple intelligent reflecting surfaces (IRSs) are located on the exact spot of the channel scatterers. We investigate the spectral efficiency (SE), benefits and drawbacks of deploying multiple IRSs in comparison with a scenario with a single or no IRS. Our simulation results show a trade-off between the number of reflecting elements and the total number of IRSs in the system.

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Classificação de Distúrbios Pulmonares em Radiografias de Tórax Usando Redes Convolucionais

Alysson Machado, Leo Araújo, Luciana Veloso

DOI: 10.14209/sbrt.2021.1570734174

Keywords: Classificação Multirrótulo Redes Neurais Convolucionais Distúrbios Pulmonares Visão Computacional

Abstract

A radiologia depende da extração de informações em imagens, sendo uma área de aplicação natural para aprendizado profundo, cujos modelos se destacam sobretudo em tarefas de Visão Computacional. Destarte, investiga-se a utilização de redes convolucionais para auxiliar radiologistas no diagnóstico dos distúrbios pulmonares: atelectasia, derrame pleural, pneumotórax, consolidação, edema, lesão e opacidade pulmonar. São exploradas arquiteturas renomadas de redes convolucionais e comitês de classificação, produzindo bons resultados na classificação multirrótulo de radiografias, com acurácia de 79,54%. Em análise subsequente, os mapas de ativação dos modelos correlacionaram positivamente com anotações realizadas por radiologistas em exames de uma base de dados independente.

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Provisionamento Multicaminho com Otimização de Particionamento de Taxa de Transmissão para Proteção Dedicada em Redes Ópticas Elásticas

Henrique A. Dinarte, Daniel Chaves, Raul C. Almeida Jr, Karcius Assis, Helio Waldman

DOI: 10.14209/sbrt.2021.1570734178

Keywords: proteção multicaminho algoritmo genético proteção dedicada com banda espremida redes ópticas elásticas

Abstract

Among the multipath protection schemes found in the literature, the Partitioning Dedicated Path Protection - PDPP proposes to divide the total transmission rate required by the connection in equal parts and then, proceed the transmission of each part using multiple disjoint paths. Nevertheless, it is also possible to partition the transmission rate unequally between paths, enabling benefits to network performance. This article proposes a meta-heuristic based on genetic algorithms to find an optmized partitioning of connections transmission rate among multiple disjoint paths, in order to provide dedicated protection and reduction in the blocking probability and average bandwidth squeezing.

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Algoritmo Rápido para Cálculo de Centroide de Imagem com Sensores Digitais de Sol do tipo CMOS para aplicação em Pequenos Satélites

Diego Coutinho, Fernando Ramborger, Antonio Alves Ferreira Jr., Evandro Cesar Vilas Boas

DOI: 10.14209/sbrt.2021.1570734179

Keywords: algoritmo centroide de imagem CMOS sensor digital de Sol

Abstract

This work presents a fast image centroiding algorithm for CMOS-based digital sun sensors. The image is interpreted as a pixel matrix. The rows and columns pixels intensities are summed and stored in vectors. The centroid coordinates (xc, yc) are obtained by checking the row and column vector index-related higher pixel intensity. This approach was compared to the basic centroiding and thresholding method with a time processing reduction of 58% and similar precision.

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Detecção de Atividade e Estimação de Canal em Acesso Múltiplo Uplink Grant-Free Usando o Algoritmo BOMP

Ana L Scharf, Bartolomeu F. Uchôa-Filho, Didier Le Ruyet

DOI: 10.14209/sbrt.2021.1570734185

Keywords: mMTC grant-free detecção de atividade de usuários estimação de canal

Abstract

Neste trabalho, consideramos o cenário massive Machine-Type Communication (mMTC) baseado no acesso múltiplo Grant-free no qual uma pequena parcela de um número maciço de usuários transmite pequenas quantidades de dados esporadicamente, sem requisitar permissão. O problema de detecção (esparsa) de atividade de usuários (DAU) pode ser resolvido com algoritmos de sensoriamento compressivo (CS), como FOCal Underdetermined System Solver (FOCUSS) e Orthogonal Matching Pursuit (OMP), que foram usados na literatura em canais com desvanecimento plano. Neste trabalho, a partir de um modelo de esparsidade em bloco e fazendo uso de uma aproximação polinomial para a resposta do canal, propomos o uso do algoritmo Block OMP (BOMP) para realizar DAU e estimação do canal (EC) de forma conjunta em canais com desvanecimento seletivo em frequência. Resultados de simulação mostram um excelente desempenho do algoritmo proposto.

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