- Marcelo Sampaio de Alencar was born in Serrita, Brazil in 1957. He received his Bachelor Degree in Electrical Enginee... moreMarcelo Sampaio de Alencar was born in Serrita, Brazil in 1957. He received his Bachelor Degree in Electrical Engineering, from Universidade Federal de Pernambuco (UFPE), Brazil, 1980, his Master Degree in Electrical Engineering, from Universidade Federal da Paraiba (UFPB), Brazil, 1988 and his Ph.D. from University of Waterloo, Department of Electrical and Computer Engineering, Canada, 1993. Marcelo S. Alencar has more than 30 years of engineering experience, and 21 years as an IEEE Member, currently as Senior Member. For 18 years he worked for the Department of Electrical Engineering, Federal University of Paraiba, where he was Full Professor and supervised 56 graduate and several undergraduate students. Since 2003, he is Chair Professor at the Department of Electrical Engineering, Federal University of Campina Grande, Brazil. Previously, he worked, between 1982 and 1984, for the State University of Santa Catarina (UDESC). He spent some time working for MCI-Embratel and University of Toronto, as Visiting Professor. He is founder and President of the Institute for Advanced Studies in Communications (Iecom). He has been awarded several scholarships and grants, including three scholarships and several research grants from the Brazilian National Council for Scientific and Technological Research (CNPq), a scholarship from the University of Waterloo, a scholarship from the Federal University of Paraiba, an achievement award for contributions to the Brazilian Telecommunications Society (SBrT), an award from the Medicine College of the Federal University of Campina Grande (UFCG) and an achievement award from the College of Engineering of the Federal University of Pernambuco, during its 110th year celebration. His biography is included in the following publications: Who's Who in the World and Who's Who in Science and Engineering, by Marquis Who's Who, New Providence, USA. He published over 230 engineering and scientific papers and 13 books: Digital Television Systems, by Cambridge, Communication Systems, by Springer, Ondas Eletromagnéticas e Teoria de Antenas, Probabilidade e Processos Estocásticos, Telefonia Celular Digital, Telefonia Digital, Televisão Digital and Sistemas de Comunicações, by Editora Érica Ltda, História da Comunicação no Brasil, Sexo Conexo, Divulgação Científica, História da Comunicação no Brasil, Soluços d´Alma, by Marcelo Sampaio de Alencar, Editor, Princípios de Comunicações, by Editora Universitária da UFPB. He also wrote six chapters, including one to the book Communications, Information and Network Security, by Kluwer Academic Publishers, and the essay Historical Evolution of Telecommunications in Brazil for the IEEE Foundation. Marcelo S. Alencar has contributed in different capacities to the following scientific journals: Editor of the Journal of the Brazilian Telecommunication Society; Member of the International Editorial Board of the Journal of Communications Software and Systems (JCOMSS), published by the Croatian Communication and Information Society (CCIS); Member of the Editorial Board of the Journal of Networks (JNW), published by Academy Publisher; Editor-in-Chief of the Journal of Communication and Information Systems, special joint edition of the IEEE Communications Society (ComSoc) and SBrT. He is member of the SBrT-Brasport Editorial Board. He has been involved as a volunteer with several IEEE and SBrT activities, including being a member of the Advisory or Technical Program Committee in several events. He served as member of the IEEE Communications Society Sister Society Board and as Liaison to Latin America Societies. He also served on the Board of Directors of IEEE's Sister Society SBrT. He is a Registered Professional Engineer. He is a columnist for the traditional Brazilian newspaper Jornal do Commercio, since April, 2000, and is currently Vice-President External Relations of SBrT. He is member of the IEICE, Japan, SBMO, SBPC and SBEB, Brazil.edit
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The performance of MC-CDMA is limited by multiple access interference (MAI). To mitigate this problem, equal BER power control (PC) was proposed for MMSE-SIC receiver, which provides a powerful solution for MAI suppression (M. Tan and Y.... more
The performance of MC-CDMA is limited by multiple access interference (MAI). To mitigate this problem, equal BER power control (PC) was proposed for MMSE-SIC receiver, which provides a powerful solution for MAI suppression (M. Tan and Y. Bar-Ness, IEEE Commun. Lett., vol. 8, pp. 348-350, 2004), wherein the power distribution on different users was derived under the assumption of perfect
Research Interests: Computer Science, Simulation, Performance Analysis, Channel Estimation, Power Control, and 13 moreError Analysis, Bit Error Rate, Rayleigh fading, Rayleigh fading channel, Error Correction, Bit error probability, Robustness, Complexity Analysis, Covariance Matrix, Power Distribution, Multiple-access Interference, Code Division Multiple Access, and Channel State Information
Este artigo apresenta uma avaliacao dos efeitos da radiacao nao-ionizante (RNI) sobre a curva-padrao de resistividade media da bacteria Escherichia coli , utilizando um sinal eletromagnetico na frequencia de 880 MHz com potencia de 10 W,... more
Este artigo apresenta uma avaliacao dos efeitos da radiacao nao-ionizante (RNI) sobre a curva-padrao de resistividade media da bacteria Escherichia coli , utilizando um sinal eletromagnetico na frequencia de 880 MHz com potencia de 10 W, para um estudo comparativo entre as cepas irradiadas e nao-irradiadas nas diluicoes 1.3 e 1.4. Foi utilizada a medida de resistividade media como parâmetro de analise, pela relacao direta entre a variacao da resistividade media e a alcalinidade do meio. Isso permite relacionar a variacao da resistividade media com a funcao excretora celular. Na analise dos resultados verificou-se uma descaracterizacao da curva-padrao de resistividade media nas cepas da bacteria submetidas a RNI, observando-se um pico de elevacao na terceira hora e valores superiores de resistividade media, quando comparadas as cepas nao irradiadas. Esse padrao de resistividade media encontrado nas cepas submetidas a RNI, caracterizado por uma variacao positiva da alcalinidade do mei...
Nanomedicina visa revolucionar os metodos para diagnostico, tratamento e prevencao de doencas usando conceitos das areas de bio-tecnologia e nanotecnologia. Nanodispositivos serao capazes de realizar essas atividades a partir de... more
Nanomedicina visa revolucionar os metodos para diagnostico, tratamento e prevencao de doencas usando conceitos das areas de bio-tecnologia e nanotecnologia. Nanodispositivos serao capazes de realizar essas atividades a partir de informacoes na escala molecular. Tarefas complexas podem tambem ser efetuadas se esses nanodispositivos forem capazes de interagir entre si e com as celulas ao redor utilizando comunicacoes moleculares. Dentro do corpo humano, existe uma pluralidade de comunicacoes moleculares. O desafio atual consiste em modelar e controlar tais sistemas de comunicacoes. Este artigo apresenta uma revisao dos sistemas de comunicacao moleculares que operam no corpo humano. Esse conhecimento e necessario para o desenvolvimento de uma infraestrutura de comunicacoes pontoa-ponto, um cenario conhecido como Internet of Bio-Nano Things (IoBNT).
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Page 1. Analysis of the Capacity Region for the Non-Cooperative Multiaccess Channel with Rician Fading Marcel0 S. Alencar. and Ian F. Blake+ University of Waterloo Department of Electrical and Computer Engineering Waterloo ...
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In this paper, an upper bound on the symbol error probability (SEP) of the M-ary $$\theta $$-quadrature amplitude modulation scheme, in a channel subject to additive white Gaussian noise (AWGN) and $$\eta -\mu $$ fading, is calculated by... more
In this paper, an upper bound on the symbol error probability (SEP) of the M-ary $$\theta $$-quadrature amplitude modulation scheme, in a channel subject to additive white Gaussian noise (AWGN) and $$\eta -\mu $$ fading, is calculated by means of the union bound. In addition, an exact and closed-form expression for the pairwise error probability (PEP) of the system is derived. The PEP expression obtained is written in terms of the Beta function and the Lauricella hypergeometric function. Another expression for the PEP, written in terms of the Beta function and the Appell hypergeometric function, and two bounds for the PEP, one lower and one upper, are also presented. An exact expression for the optimum rotation angle for quadrature phase shift keying constellation, considering this channel model, is also determined. In addition, an analysis, in terms of PEP, of the modulation diversity system combined with a maximum ratio combining receiver in channels subject to $$\eta -\mu $$ fading and AWGN noise, is performed. PEP and SEP curves, as a function of signal-to-noise ratio, are plotted and corroborated by simulations performed with the Monte Carlo method under different parameters that characterize the channel mathematically. All the expressions determined in this article are closed and new.
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Novel, simple, and accurately approximated expressions for the probability of detection of Gaussian signals in \(\eta -\mu \), \(\kappa -\mu \), and \(\alpha -\mu \) fading channels at the output of an energy detector subject to impulsive... more
Novel, simple, and accurately approximated expressions for the probability of detection of Gaussian signals in \(\eta -\mu \), \(\kappa -\mu \), and \(\alpha -\mu \) fading channels at the output of an energy detector subject to impulsive noise (Bernoulli-Gaussian model) are presented. The generalized Gauss-Laguerre quadrature is used to approximate the probability of detection as a finite sum. Monte Carlo simulations corroborate the accuracy of the approximations. The results are further extended to cooperative detection with hard decision combining information.
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Abstract This paper presents a performance analysis of two MPSK detection schemes for flat Rayleigh fading channels with imperfect channel estimation. Closed-form expressions for the bit error probability (BEP) of both schemes are... more
Abstract This paper presents a performance analysis of two MPSK detection schemes for flat Rayleigh fading channels with imperfect channel estimation. Closed-form expressions for the bit error probability (BEP) of both schemes are presented considering QPSK ...
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This work presents results of a study concerning joint use of antenna arrays and eigenanalysis method for inter symbolic interference reduction without using a training sequence. The cancellement capacity of the eigenanalysis method is... more
This work presents results of a study concerning joint use of antenna arrays and eigenanalysis method for inter symbolic interference reduction without using a training sequence. The cancellement capacity of the eigenanalysis method is applied to reduce the multipath propagation effect, beamforming the path of the desired signal and attenuating undesirable paths. This equalization is analyzed in frequency and time
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Page 1. Simulated Annealing for Robust VQ: Improving Image Transmission through a Fading Channel Waslon TA Lopes E Madeiro Marcel0 S. Alencar Benedito G. Aguiar Neto* Laboratdrio de Comunica@es, DEE, COPELE ...
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Page 1. Eigencanceler Study Applied to Local Scatter Channel Model Wamberto J. L. Queiroz and Marcelo S. Alencar Federal University of Campina Grande, Campina Grande PB, Brazil Abstract-This paper presents a comparative ...
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Page 1. Comparative Performance of Compact Linear and Circular Antenna Arrays with MRC Combiner for Uniform and Gaussian DOA Probability Distributions Wamberto JL Queiroz and Marcelo S. Alencar University of Fortaleza ...
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Page 1. Performance Evaluation of a Selective Cooperative Scheme for Wireless Sensor Networks Marcelo P. Sousa Institute for Advanced Studies in Communications, UFCG Campina Grande, PB, Brazil marporsou@iecom.org.br ...
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ABSTRACT This paper presents an analysis of spectrum sensing to determine if a signal, measured by a cognitive user in an AWGN channel, is a valid one, from the primary user, or if it is composed of noise alone. The proposed method for... more
ABSTRACT This paper presents an analysis of spectrum sensing to determine if a signal, measured by a cognitive user in an AWGN channel, is a valid one, from the primary user, or if it is composed of noise alone. The proposed method for spectrum sensing is based on statistical tests to identify if the probability distribution of the received signal has noise characteristic, or other distribution that classifies it as a primary user. The results of Monte-Carlo simulations indicate that it is possible to identify transmission opportunities using spectrum sensing tests with low signal-to-noise ratio.
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The wireless channel has characteristics of multipath fading, due to reflection, refraction and scattering. Modulation diversity is a bandwidth-efficient diversity technique that uses rotation, associated with the interleaving between the... more
The wireless channel has characteristics of multipath fading, due to reflection, refraction and scattering. Modulation diversity is a bandwidth-efficient diversity technique that uses rotation, associated with the interleaving between the in-phase and quadrature components of a digital signal constellation. It is intended to mitigate the effects of fading in wireless communications. The research considered a scenario in which multiple paths are simulated, with associated random multiplicative noise and delay. The multipath fading effect is studied in this scenario, and a comparison between the BER values for 4-PSK and 8-PSK transmission is presented, to evaluate the gain provided by the modulation diversity scheme. An analysis concerning optimum rotation angles is performed, considering eight multipath scenarios, including cases with severe fading effect.
Abstract The fluctuation in the received signal level, caused by diverse factors, that affect the electromagnetic wave propagation in a channel is studied. The signal behavior is analyzed for a channel that presents flat or frequency... more
Abstract The fluctuation in the received signal level, caused by diverse factors, that affect the electromagnetic wave propagation in a channel is studied. The signal behavior is analyzed for a channel that presents flat or frequency selective fading. Numerical simulations were ...
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Page 1. Desempenho do Roteamento Adaptativo-Alternativo em Redes Ópticas Dinâmicas Paulo Ribeiro L. Júnior1, Michael Taynnan2, Marcelo S. Alencar1 1Departamento de Engenharia Elétrica (DEE) Instituto de Estudos ...
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A mobile telephone system is defined as a communication network via radio which allows continuous mobility by dividing its coverage area into cells. Wireless communications, on the other hand, imply radio communications without... more
A mobile telephone system is defined as a communication network via radio which allows continuous mobility by dividing its coverage area into cells. Wireless communications, on the other hand, imply radio communications without necessarily requiring handover from one cell to another during an ongoing call (Nanda and Goodman 1992).
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As redes de quinta geracao (5G) possibilitarao uma maior taxa de transmissao (superior a 10 Gbit/s), menor latencia (abaixo de 1 ms), alta confiabilidade, maior densidade de conectividade e uma maior mobilidade do que as tecnologias... more
As redes de quinta geracao (5G) possibilitarao uma maior taxa de transmissao (superior a 10 Gbit/s), menor latencia (abaixo de 1 ms), alta confiabilidade, maior densidade de conectividade e uma maior mobilidade do que as tecnologias anteriores. Para suportar uma grande diversidade de servicos com diferentes requisitos de desempenho, as redes 5G necessitam de uma arquitetura de rede movel escalavel, adaptavel e programavel. Este artigo descreve os pontos-chave para que as redes 5G atendam as exigencias dos servicos, com enfase nas novas tecnologias incorporadas, nova arquitetura da rede e os cenarios para a implementacao.
Redes de sensores sem fio (RSSF) tem se tornado um pilar importante em diversos cenarios de aplicacao (e.g. internet das coisas, cidades inteligentes, agricultura de precisao, etc). Muitos estudos acerca das RSSF, que possibilitaram o... more
Redes de sensores sem fio (RSSF) tem se tornado um pilar importante em diversos cenarios de aplicacao (e.g. internet das coisas, cidades inteligentes, agricultura de precisao, etc). Muitos estudos acerca das RSSF, que possibilitaram o aperfeicoamento da tecnologia, tiveram as ferramentas de simulacao como um importante recurso para viabilizar a sua conducao, devido ao menor custo e tempo necessario quando comparado com testbeds. Mesmo diante dos diversos trabalhos cientificos que empregaram ferramenta de simulacao para viabilizar o estudo, algumas investigacoes tem apontado para possiveis problemas acerca das ferramentas de simulacao em RSSF (e.g. Modelos de simulacao nao realistico). Este trabalho teve como objetivo avaliar a confiabilidade da ferramenta de simulacao em RSSF, Castalia, com base em um testbed equivalente. Os resultados demonstraram que a ferramenta de simulacao nao contempla as nuances previstas no tocante a descarga da bateria e, como consequencia, variacao do traf...
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ABSTRACT This paper describes a Qt-based C++ application for full-reference stereoscopic video quality assessment. The application is platform independent and provides a friendly Graphical User Interface (GUI). The stereoscopic video... more
ABSTRACT This paper describes a Qt-based C++ application for full-reference stereoscopic video quality assessment. The application is platform independent and provides a friendly Graphical User Interface (GUI). The stereoscopic video signals used in the application are based in two-view model, such as the H.264/AVC standard with Multiview Video Coding (MVC), and several spatial resolutions are available. The application provides objective video quality algorithms, such as PSNR, SSIM and PW-SSIM and incorporates a recently published technique for stereoscopic video quality assessment, called disparity weighting (DW), DPSNR, DSSIM and DPW-SSIM. Numerical results corresponding to the performance of the objective measurements acquired using the proposed application are presented. The ultimate goal is that the application will contribute, as an open-source tool to be used by academia and industry, for standardization and development of objective algorithms and evaluation of impairments in stereoscopic video signals caused by some processing techniques.
ABSTRACT This paper presents new results on the objective evaluation of stereoscopic video quality. A balance between the scores provided by classical objective algorithms and the disparity information of the reference video is found. The... more
ABSTRACT This paper presents new results on the objective evaluation of stereoscopic video quality. A balance between the scores provided by classical objective algorithms and the disparity information of the reference video is found. The performance of the proposed technique was verified using statistical metrics (correlation coefficients and root mean square error) that compare the scores provided by the objective algorithms and the subjective results provided by the NAMA3DS1-COSPAD1 stereoscopic video quality database. The obtained results suggest a significant improvement on the performance of the objective algorithms for the proposed technique.
Page 1. A Frequency Domain Approach to the Optimization of Scalar Quantizers Marcelo S. Alencar *t Universidade Federal da Paraiba Departamento de Engenharia Elbtrica AV. Aprigio Veloso, 882 Campina Grande PB Brad ...