Proposition of a Hybrid Topology for Photonic Switched Optical Networks

Felipe R. Barbosa, Indayara B.Martins, Edson Moschim, Luiz H. Bonani

DOI: 10.14209/sbrt.2012.151

Keywords: Photonic Switching Optical Packet Networks Linkfailure Optical Fiber Communications.

Abstract

Use of Photonic Switching in Optical Networks seems to be one of the best solutions for traffic optimization in Metropolitan Access. Here we propose optical packet/burst switching (OPS/OBS) networks as a future-proof solution for high-throughput in the highly variable traffic pattern of the metro-access. Through analytic modeling and computer simulations we evaluate network performance of mesh networks having a hybrid topology of the Manhattan St.-type. We combine nodes of interconnection grade-2 and grade-3 in order to optimize and balance simultaneously network performance and cost. For performance metrics the parameters packet loss fraction and average number of hops are adopted, link and node loads are investigated, and effective network capacity is evaluated. Results clearly indicate improvement of capacity over grade-2 networks, and possibility of cost savings over complete grade-3 installations

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Um Esquema de Agregação para Economia de Energia em Descoberta de Serviços para MANETs

Janine Kniess, Orlando Loques, Célio V. N. Albuquerque

DOI: 10.14209/sbrt.2012.150

Keywords: Selection Service Data Fusion Fault-Tolerance.

Abstract

This work proposes a service discovery protocol based on localization to MANETs. This protocol proposes a service selection mechanism with data fusion that dynamically selects the best resource providers during the reply transmissions in order to reduce the energy consumption and improve the network lifetime. Another issue addressed in this work is a fault-tolerant service discovery mechanism based on localization that explore redundancy to guarantee the delivery of packets in MANETs.

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Interference management and antenna downtilt in multi-antenna CoMP systems

Rodrigo L. Batista, Yuri C. B. Silva, Elvis M. G. Stancanelli, Francisco R. P. Cavalcanti

DOI: 10.14209/sbrt.2012.155

Keywords: Interference management Coordinated Multi-Point (CoMP) precoding algorithms.

Abstract

Long Term Evolution (LTE)-Advanced has regarded both Coordinated Multi-Point (CoMP) and Multiple Input Multiple Output (MIMO) technologies as an efficient means of meeting the International Mobile Telecommunications (IMT)-Advanced requirements. In this context, efficient Radio Resource Allocation (RRA) strategies are required to exploit the available spatial degrees of freedom, coordinate the resources usage and manage the interference in order to obtain performance gains. This paper provides system-level analyses in a downlink multi-antenna CoMP system for the performance gains achieved with the inter-cell interference management through antenna downtilt and the use of interference estimates in RRA strategies such as spatial precoding and power allocation. For both spatial diversity and multiplexing schemes, the results showed that quite high performance gains in terms of system spectral efficiency are achieved through antenna downtilt and that RRA strategies always benefit from estimates of the inter-cell interference.

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Design and Implementation of Fast Fourier Transform Algorithm in FPGA

Adriana Bonilla R., Roberto J. Vega L., Karlo G. Lenzi, Luís G. P. Meloni

DOI: 10.14209/sbrt.2012.152

Keywords: FFT VHDL FPGA Radix-4 Dragonfly.

Abstract

This paper shows a design and implementation of a radix-4 FFT in FPGA using a Xilinx Spartan-6. The decimation in time equations are reviewed and in sequence several FPGA modules are presented according to algorithm architecture looking for optimization in execution time and occupied device area. Several tests were performed in order to validate the algorithm performance, FFT functionality, and time performance analysis. The proposed architecture is of low cost and very efficient for FFT computation.

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Decodificação por Apagamento Ponderado Aplicada a Códigos com Proteção Desigual de Erros

Rebecca C. de Albuquerque, Daniel C. Cunha, Cecilio Pimentel

DOI: 10.14209/sbrt.2012.156

Keywords: unequal error protection soft decision decoding computational complexity.

Abstract

This work analyzes, through computer simulations, the effectiveness of the weigthed erasure decoding (WED) algorithm applied to unequal error protection block codes using binary transmission over an additive white Gaussian noise channel. The performance of the WED algorithm is compared to maximum likelihood decoding one and an evaluation of the tradeoff between performance and complexity of the WED algorithm for each class of protection is provided.

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Um estudo de reticulados obtidos via Construção B

Grasiele C. Jorge, Antonio A. Campello Jr., Sueli I. R. Costa

DOI: 10.14209/sbrt.2012.153

Keywords: q-ary codes Construction A Construction B Integer lattices.

Abstract

In this work we present a generalization of the so called Construction B of [3] for classes of q-ary codes with q 2 N and also some relations between the Constructions A and B. We show that the lattice obtained from a q-ary code via Construction B has qDn as sub-lattice and can alternatively be viewed as the Construction A of a 2q-ary code. Finally, we study an adaptation of the “Sphere decoding” algorithm for lattices obtained via Construction B from q-ary codes, q prime, in the sum metric.

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Análise de desempenho do Algoritmo de Water-filling Modificado para Alocação de Recursos em Sistemas OFDMA

Anderson Daniel Soares, Luciano Leonel Mendes, Rausley Adriano Amaral de Souza.

DOI: 10.14209/sbrt.2012.157

Keywords: OFDMA Water-filling Throughput Robustness Frequency Selective Channels.

Abstract

The growth of mobile communication systems with high data rate capacity and multiple users is pushing the researches about techniques that presents high spectrum efficiency. OFDMA is already a reality in many advanced mobile communication systems, such as LTE, IEEE802.16 and IEEE802.22. Nevertheless, the efficiency of the OFDMA technique depends on the resource allocation algorithm, which must consider the data rate and bit error rate (BER) required by each user and the channel frequency response to determine which subcarriers and the modulation orders shall be allocated for each user. The aim of this paper is to analyze the performance of a resource allocation algorithm, based on Water-filling theorem, but that has been modified to consider the required throughput of each user. The performance analysis includes the efficiency of the algorithm to fulfill the users requirements about throughput and robustness in a frequency-selective channels.

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Ferramenta Computacional para Análise de Antenas Filamentares Utilizando o Metodo dos Momentos

Eduardo dos Santos Silveira, Marcos V. T. Heckler

DOI: 10.14209/sbrt.2012.154

Keywords: method of moments integral-equation methods wire antennas Galerkin Method.

Abstract

This paper presents the implementation of a computational tool that performs the calculation of the current distribution in wire antennas using the Method of Moments (MoM). For this purpose, different approaches were used: the Point-Matching Method and the Galerkin Method. Both were implemented in Matlab R . To demonstrate the use of the tool, a half-wavelength dipole has been analyzed considering different basis functions. In terms of radiation pattern, it was observed that the kind of basis function does not affect the results significantly. The convergence of the MoM for the computation of input impedance has been studied. It has been verified that all the curves approach the same value as the discretization is increased regardless of which basis function is employed in the calculations

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Análise de Tecnologias Disponíveis para Infraestrutura Doméstica em Sistemas IPTV

Robert Christian Moritz Cantarutti Junior, Felipe Greco, Carlos Marcelo Pedroso

DOI: 10.14209/sbrt.2012.158

Keywords: Multimedia IPTV home networking

Abstract

This paper presents an evaluation of available technologies to implement home networking infrastructure for IPTV systems. The study was made using using legacy cabling technologies, because most the residential facilities do not adapt to the Brazilian standards for structured cabling. Quantitative tests were performed in a laboratory environment. A qualitative study assessing aspects such as ease of installation, bandwidth, range, security, standards compliance and implementation costs are presented

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Um Contador Controlado por Semáforos Para a Correção de PCR

Heitor J. Savino, Eddie B. L. Filho

DOI: 10.14209/sbrt.2012.164

Keywords: Correçãoo de PCR MPEG-2 fluxo de trans-porte semáforo

Abstract

O fluxo de transporte MPEG-2 é muito utilizado na transmissão de áudio, vídeo e dados multiplexados, fornecendo bases de tempo para os programas enviados. Esta informação, conhecida como PCR e também responsável pela sincronização do receptor, pode sofrer erros durante a sua transmissão, devido à cadeia de processamento entre transmissor e receptor. Este artigo introduz um novo método de correções de PCR, baseado em um contador controlado por semáforos, que é capaz de fornecer uma referência de tempo estável para o decodificador. A arquitetura do módulo de correções, que possui características como complexidade computacional e requisitos de hardware reduzidos, é apresentada e comparada a métodos tradicionais. Resultados de simulação mostram que o método proposto é eficaz e mantém um baixo nível de jitter na saída do sistema.

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