XXXIII Simpósio Brasileiro de Telecomunicações
Close Expressions for Meyer Wavelet and Scale Function
Victor Vermehren Valenzuela, Hélio Magalhães de Oliveira
Keywords: Meyer wavelets multiresolution analysis scale function
AbstractMany continuous wavelets are defined in the frequency domain and do not have analytical expressions in the time domain. Meyer wavelet is ordinarily defined in this way. In this note, we derive new straightforward analytical expressions for both the wavelet and scale function for the Meyer basis. The validity of these expressions is corroborated by numerical computations, yielding no approximation error.
M2M Protocols for Constrained Environments in the Context of IoT: A Comparison of Approaches
Edielson P. Frigieri, Daniel Mazzer, Luís F. C. G. Parreira
Keywords: Constrained Internet of Things Machine-to- Machine Security Scalability
AbstractThe Internet of Things movement opens new possibilities for services and business along with new technological challenges, such as power efficiency, operation in constrained environments, security, and privacy. With the expectation of a high amount of devices connected in this Future Internet, scalability is also assumed to be a challenge. To address these limitations, several protocols are being proposed. In this paper, two of them, MQTT and COAP, are presented and qualitatively compared, summarizing their main features and limitations, highlighting the best scenarios where each approach is more suitable.
Transmissão de Sinais de Telecomunicações utilizando o USRP
Tadeu N. Ferreira, Paulo S. R. Diniz, Marcele O. K. de Mendonça
Keywords: software-defined radio USRP GnuRadio
AbstractThis article analyzes SDR technology implemented in multicarrier USRP systems using GnuRadio. The pace of technological development requires a constant evolution on the cellular devices, imposing to the user a constant replacement of the current mobile equipment. SDRs allow the simple recon- figuration of the mobile equipment software, easily re-adapting it to the new scenario. Principles underlying SDR and OFDM are explained, as well as the USRP. Some experimental data are analyzed, in order to assess the system feasibility.
User Identification and Key Regeneration System Employing Rotated Reference Images of the Iris
Guilherme Nunes Melo, Valdemar C. da Rocha Jr., José S. Lemos-Neto
Keywords: Iris code biometry coding authentication
AbstractA new test called rotation search is proposed for user identification and cryptographic key regeneration in systems employing a digital representation of the iris (iris code). When applied to the BIOSECURE, CASIA and NIST-ICE data bases the rotation search shows, on average, a two fold reduction in false rejection ratio (FRR) with a false acceptance ratio (FAR) equal to zero, in comparison with the standard search employed in other systems. The highest improvement reached in FRR by the rotation search against the standard search is 100 times, and in many cases the measured FRR is equal to zero.
Ensaio sobre a Neutralidade de Rede no Brasil
Márcio A. de Deus, Paulo H. P. Carvalho, João Paulo Leite
Keywords: Neutralidade de Rede Tráfego Internet Economia da Internet Internet Engenharia de Tráfego Roteamento Planejamento
AbstractA neutralidade da rede tem um significado diferente em diferentes países , sendo esta uma discussão importante, pois os prestadores de serviços, provedores de conteúdo e usu ários fina is precisam ter o mesmo entendimento com relação às funções e papeis uns dos outro s. A discussão não deveria ser conduzida de forma apenas bipolar, entre provedores de serviço de acesso e de conteúdo. Outro ponto importante é se verificar se toda s as interpretações são realmente independentes. A continuidade do serviço Internet também deve s er discutida de forma econômica, mas sem deixar de analisar o ponto de vista técnico . As definições e terminologias também deveriam seguir aspectos mais técnic os, porém sem se basear apenas nas tecnologias atuais, desconsiderando - se a evolução. Neutralidade da rede não pode significar a prestaç ão de serviços sem nenhum custo, pois no fim isto poder ia significar o fim da Internet e de seu crescimento.
The Influence of the Symbol Detection Error on Cooperative In-home Power Line Communication based on HS-OFDM Scheme
Michelle S. P. Facina, Moises V. Ribeiro
Keywords: Cooperative in-home PLC channel maximum data rate AF and DF protocols symbol detection error
AbstractThis work analyzes the influence of symbol detection error on cooperative in-home power line communication base d on channel estimates provided by a measurement campaign. We investigate cooperation communication based on a single relay model in which the relay node is situated in different locations between source and destination nodes by consider ing closed-form expressions of the maximum data rate of hermiti an symmetric orthogonal frequency division multiplexing sch eme with frequency domain equalizer based on minimum mean square error and zero-forcing criteria. The analysis is car ried out over the amplify-and-forward (AF) and decode-and-forw ard (DF) protocols together with maximal ratio combining techn ique. Numerical results show that the advantage of the DF protocol relative to AF one ends when the symbol detection error achie ves a threshold and this threshold depends upon relative locati on of the relay node regarding source and destination nodes.
Projeto e Caracterização de Acopladores para Power Line Communications
Lu ́ıs Guilherme da S. Costa, Ant ˆonio Angelo M. Picorone, An t ˆonio Carlos M. de Queiroz, Vin ́ıcius Lagrota R. da Costa, Mois ́es V. Ribeiro
Keywords: Power Line Communications coupler Microstrip
AbstractThis paper discusses the project of capacitive cou- plers for Power Line Communications (PLC) in the range frequency of 9 kHz to 500 kHz and 1,7 to 500 MHz for low voltage networks. The use of Microstrip technique to design printed circuit boards and other relevant decisions in the p roject are proposed. The results based on these decisions indicate that the approach discussed in this work can be applied with good results when it comes to matter the safety requirements and t he results obtained in the characterization of PLC couplers.
Codificação LDPC em sistemas de transmissão de imagens do satélite CBERS-2B
Paulo H. Souza Nunes, Renato M. Oliveira Filho, Fábio S. Marques
Keywords: LDPC Remote Sensing Transmis- sion CBERS-2B Satellite
AbstractThis work seeks to reduce the bit error rate (BER) using LDPC codes (Low Den- sity Parity Check Code) as error correcting code. These codes are known since 1963 and they are based on the Robert Gallager’s research. Images may have vary modifications caused by instru- mental errors (sensors). The results show the degradation caused and error correction using LDPC codes for channels with 1 until 4 errors of a remote sensing image captured from CBERS- 2B satellite.
Análise Espectral de um Mapa Caótico Baseado na Função Tangente Hiperbólica
Carlos E. C. Souza, Daniel P. B. Chaves, Cecilio Pimentel
Keywords: Chaotic communication dynamical systems itera- tive maps Lyapunov exponent power spectral density
AbstractThis work generalizes the chaotic map recently introduced by the authors with the addition of two new contro l parameters. The Lyapunov exponent is employed to analyze th e chaotic dynamics of the proposed map. The spectral characte ris- tics of chaotic signals generated by this map as a function of the control parameters are also investigated. The proposed map can be used in symbolic dynamics based communication systems wi th advantages over current approaches based on piecewise line ar maps.
Fabricação e testes de antenas de microfita aplicadas à tecnologia 5G
Vanessa P. R. Magri, Tadeu N. Ferreira, Thiago R. Paiva, Victor R. L. do Amaral, Janey Rodríguez García, Fernanda S. C. Leomil
Keywords: 5G Printed Antenna Microstrip Antenna Path los
Abstracthis paper presents the fabrication and experimental characterization of 7 printed microstrip antennas prototypes with rectangular pattern for application to the new fifth generation wireless communications technology (5G). These antennas are characterized according to a path loss test in an indoor environment at Fluminense Federal University ́s propagation laboratory using a carrier ( fc ) of 10 GHz. The experimental results are compared with the simulation results and present a bandwidth of 250 MHz for 10 GHz. It can reach up to 1 GHz of transmission bandwidth in a 26 GHz carrie