Reticulados LDPC com Codificação e Decodificação Eficiente e uma Generalização da Construção D 0

Paulo Ricardo Branco da Silva, Danilo Silva

DOI: 10.14209/sbrt.2017.76

Keywords: Construction D 0 lattices LDPC codes multilevel codes multistage decoding

Abstract

We propose linear-time encoding and decoding al- gorithms for multilevel LDPC lattices based on Construction D 0 . Moreover, a generalization of Construction D 0 is proposed which leads to a new class of multilevel lattices. Based on this construction, two-level LDPC lattices are designed that achieve performance comparable to that of polar lattices in the power- unconstrained AWGN channel.

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The Impact of Spectrum Sharing Strategies on the E2E Performance of Machine Type Communication

M. V. M. Bassi, C. H. M. de Lima, A. A. Ferreira

DOI: 10.14209/sbrt.2017.77

Keywords: MTC IEEE 802.11 self-organization spectrum sensing cognitive radio

Abstract

This paper addresses spectrum sensing and sharing strategies for machine type communication in the cognitive net- works. We assess how such solutions preserve the transmissions of the primary nodes, as well as their impact on the performance of the underlay secondary network. The system-level performance is evaluated by means of computer simulations using the Monte Carlo approach. Our results show that primary nodes signif- icantly benefit from the proposed spectrum sharing strategies, whereas the secondary devices may be severely compromised depending on their relative disposition relative to nodes higher priority. Moreover, there exist an inherent trade off between the quality of service experienced by the primary user and the overall spectrum efficiency in terms of the number simultaneous transmission in the underlay secondary network.

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Análise de técnicas de otimização multiobjetivo para o posicionamento de controladores em redes SDN

Ana Carolina de Oliveira Christófaro, Marcelo Menezes de Carvalho, Daniel Guerreiro e Silva

DOI: 10.14209/sbrt.2017.78

Keywords: SDN NSGA-II PSA

Abstract

Software Defined Network is a traffic engineering solution with an increasing interest by industry, which raises issues such as the use of multiple controllers. Considering that the positioning of controllers within a given topogoly constitutes a multiobjective optimization problem in order to satisfy certain performance metrics, this work presents a comparative analysis between PSA and NSGA-II, based on the initial study developed by Lange et al. [1]. The results yield good results for both techniques, in terms of accuracy and processing time, but with an advantage to NSGA-II algorithm, in terms of convergence and exploration degree of the search space. Such properties are interesting when one considers real time traffic optimization and a resilient network operation.

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Fall Monitor: Detector de Quedas para Dispositivos Móveis para Cuidado à Pessoas com Mobilidade Debilitada

Lukas M. Torquato, André Felipe Monteiro, Felipe da Rocha Henriques

DOI: 10.14209/sbrt.2017.79

Keywords: Fall detection Android Smartphone

Abstract

Elderly, patients who suffered from strokes, neurological, articular, cardiovascular illness and other diseases like muscular dystrophies are examples of cases which affects an individual’s mobility. Thus, remote monitoring and care is an effective way to avoid the worsening of these sequels. With this question in mind, the development of a tool for smartphones to assist the caretaking, capable of detecting a injured patient’s fall, was initiated, which alerts a caregiver and makes easier the arrival of help to rescue the monitored user in a quicker and more effective manner.

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Análise de Desempenho de Protocolos Multicaminho para Vı́deo Streaming em Tempo Real

Guilherme Fernandes de Souza Miguel, Carlos Alexandre Gouvea da Silva, Carlos Marcelo Pedroso, Eduardo Parente Ribeiro

DOI: 10.14209/sbrt.2017.80

Keywords: Multihoming multipath video streaming

Abstract

The mobile devices technological evolution and the increased availability of IP (Internet Protocol) networks, created new opportunities for multimedia content distribution over Internet. Real-time applications require high quality service and are not tolerant to mean packet delay above 200ms, delay variations and throughtput reduction. The use the multipath protocols in real-time video streaming presents several advan- tages, leading to a better quality and network resilience. This paper presents a study on performance of high definition video streaming, using multipath transport protocols, comparing the Stream Control Transfer Protocol (SCTP), Concurrent Multipaht Transfer (CMT), and a path selection technique based on the lower path delay called delay centric.

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Demultiplexadores para WDM sobre fibras ópticas plásticas com base em filtros gel

Rafaella D. Oliveira, Michele C. Zanon, Leonardo Campos, Ricardo M. Ribeiro, Vinícius N. H. Silva

DOI: 10.14209/sbrt.2017.81

Keywords: Data communication networks Plastic optical fibres Plastic films WDM Optical filters

Abstract

This work of Scientific Initiation describes the development of demultiplexers (DEMUXs) for wavelength- division multiplexing (WDM) over PMMA (poly-methyl- metacrylate) plastic optical fibre links using visible laser diodes. The DEMUXs were built from the combination of POF-splitters with gel plastic filters. The latter operates as high-pass or band- pass optical filters, are practical, simple, malleable and cost- effective. The filters can be spectrally tuned by mixing and stacking plastic layers with different colors and thickness.

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Proposta Alternativa para Obtenção da Solução Ótima do Problema de Maximização da Eficiência Energética com Restrições de QoS

Weskley V. F. Mauricio, F. Rafael M. Lima, Tarcı́sio F. Maciel, Francisco R. P. Cavalcanti

DOI: 10.14209/sbrt.2017.82

Keywords: Radio Resource Allocation Energy Efficiency and Quality of Service

Abstract

In this article we revisit the Radio Resource Allo- cation (RRA) problem of maximizing the ratio from the total data rate and the total utilized power subject to the QoS satisfaction (PMEE). It was previously studied in [1] and one optimal solution was obtained. However, that solution has a very elevated computational cost. In this article, we will use the algorithm proposed in [2] to obtain a optimal solution to the problem with a very low computational cost compared to that previously proposed solution. We will see high gains in terms of computational complexity and a low iteration number of necessary iteration to obtain the optimal solution through the proposal solution.

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Novo Algoritmo para Conformação de Feixe e Seleção de Antenas em Sistemas de Comunicações Móveis

Guilherme M. Zilli, Ciro A. Pitz, Eduardo L. O. Batista, Rui Seara

DOI: 10.14209/sbrt.2017.2

Keywords: Adaptive arrays antenna selection beamforming MVDR problem

Abstract

This paper presents a new adaptive algorithm for solving the problem of joint antenna selection and beamform- ing in mobile communication systems. The proposed antenna selection technique is based on minimizing the co-channel interference, whereas the beamforming is carried out using a formulation of the minimum-variance distortionless-response (MVDR) criterion targeted to systems with a limited number of radio-frequency chains. Numerical simulation results corroborate the effectiveness of the proposed algorithm.

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Modelo para Avaliação de Modulações Digitais na Faixa de Ondas Milimétricas

Tiago Magalhães dos Reis, Dayan Adionel Guimarães

DOI: 10.14209/sbrt.2017.84

Keywords: Desbalanceamento I-Q modulações digitais não-linearidade ondas milimétricas ruído de fase

Abstract

Sistemas de comunicação sem fio operando na faixa das ondas milimétricas estão sujeitos a fortes degradações causadas pelo canal e por imperfeições de hardware como ruído de fase, desbalanceamento I-Q e não-linearidade dos amplificadores. Neste artigo, recentes modelos de imperfeições e de canal com desvanecimento propostos na literatura são combinados em um novo modelo. O objetivo é avaliar o desempenho das modulações FSK com detecção não-coerente, PSK e QAM com detecção coerente através desse novo modelo. Resultados apontam que a modulação FSK não é uma solução incondicionalmente robusta frente a tais degradações, como recentemente defendido na literatura.

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Wireless Physical-layer Security Using Precoding and an Active Eavesdropper

Pedro Ivo da Cruz, Ricardo Suyama, Murilo Bellezoni Loiola

DOI: 10.14209/sbrt.2017.85

Keywords: wireless physical-layer security channel estimation precoding blind equalization

Abstract

The wireless physical layer security can assist traditional encryption mechanisms by generating the keys, for instance. However, some techniques allow hiding information directly in the physical layer, such as performing precoding at the legitimate user information about the channel, such as the received signal strength or the phase response. Most works on this kind of precoding also considers a passive eavesdropper. This work considers an active eavesdropper and proposes the use of a precoder based of the full channel impulse response. The results show the effectiveness of the proposed technique to secure the information transmission.

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