Artigos científicos, teses e dissertações
Publicados nas melhores instituições de ensino

Análise de desempenho de uma rede local sem fio para aplicações multimídia

This work presents a methodology that supplies subsidies in order to evaluate the acting of multimedia applications in Wireless Local Area Network. To understand the context of the work first we described some theoretical fundamentals on Wireless Local Area Network (WLAN) and Mul...

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Medição de Qualidade de voz em Wireless utilizando os codecs G711,G729,G723 e GSM / Measurement of quality of a wireless voice codecs using the G711, G729, G723 and GSM

Esta dissertação analisa a qualidade da transmissão do VoIP (Voz sobre IP) em rede WLAN (Wireless Local Área Network). Para atingir esse objetivo foram realizados testes em bancada utilizando os codecs de voz G729, G711, G723 e GSM analisando suas características de atraso e perd...

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A dual tuned Complementary Structure Frequency Selective surface for WLAN applications

A single substrate layer double metallic plane frequency selective surface (FSS) is designed with miniaturized electrical elements and two tunable pass-bands enabling Wireless Local Area Network applications. Each FSS periodic cell consists of a metallic square loop on the top me...

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Energy Efficient Rate Adaptation Algorithm for FiWi Access Network

Abstract Similar to any telecommunication network, energy efficiency is a desirable feature for fiber wireless (FiWi) access networks. These networks have optical back end and wireless front end. Both ends may contribute for energy efficiency. This work focuses on front end of Fi...

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Distribuição de weibull na emulação de canal em redes WLAN para avaliação de VoIP / Weibull distribution in WLAN channel emulation for VoIP evaluation

O trabalho investiga de forma quantitativa e qualitativa o desempenho de VoIP (Voz sobre IP) em uma rede WLAN (Wireless Local Área Network), denominado WVoIP, (Wireless VoIP) considerando degradação em ambiente indoor. Para atingir esse objetivo foram realizados testes utilizando...

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PROPAGATION MEASUREMENT IN 2.4 GHZ FOR WIRELESS LOCAL AREA NETWORK PLANNING / MEDIDAS DE PROPAGAÇÃO EM 2.4 GHZ PARA O PLANEJAMENTO DE REDES LOCAIS DE ACESSO SEM FIO

As Redes locais sem fio (WirelessLAN ou WLAN) surgiram como uma alternativa as redes convencionais com fio (LAN), de uma forma mais flexível, de fácil configuração e boa conectividade em áreas fechadas (prediais) ou abertas (campus). Elas combinam a mobilidade do usuário com sua ...

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Avaliação de desempenho de redes sem fio 802.11b

Wireless Local Area Networks (WLANs) have grown a lot with the popularity of the 802.11 standard. WLAN is different than network wired, it has some specific features from wireless technology and use parameters to configure that affect performance and interoperability. This assign...

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Mecanismo de autenticação baseado na localização de estações sem fios padrão IEEE 802.11 / IEEE 802.11 authentication mechanism based on wireless station location

A vantagem das redes locais sem fios, as quais permitem que uma estação móvel possa deslocar-se livremente dentro da área de abrangência da rede, possui uma contrapartida em termos de segurança. A possibilidade dos sinais de microondas atravessarem paredes e sofrerem atenuação, r...

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TOLERÂNCIA À FALHA DOS AGENTES DE MOBILIDADE DO PROTOCOLO MOBILE IP / FAULT TOLERANCE OF MOBILITY AGENTS OF PROTOCOL MOBILE IP

The growth of the Internet, as much of the point of view of the number of users as of the offered services, and the fast progress of the wireless communication technology, it became possible a demand for wireless systems that allow the access the Internet. However, one of the mai...

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New strategies for planning and performance evaluation of wireless networks: case studies based on the cross-layer approach

The use of wireless local area networks, called WLANs, as well as the proliferation of the use of multimedia applications have grown rapidly in recent years. Some factors affect the quality of service (QoS) received by the user and interference is one of them. This work presents ...

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Dynamic EDCF parameters for QoS control in IEEE 802.11 hot spots

This paper describes a control mechanism for dynamic selection of Quality of Service (QoS) parameters used in a IEEE 802.11e Wireless Local Area Network (WLAN). The 802.11e specification, still under development, provides a new contention-based access method, called Enhanced Dist...

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Uma plataforma para avaliar a degradação da vazão causada por interferência espectral em redes sem fio padrão IEEE 802.11 / A platform for evaluating the degradation the flow caused by the spectral interference in wireless networks IEEE 802.11

A interferência espectral gera patologias nos sistemas de comunicação sem fio (wireless), como por exemplo, quedas na comunicação e degradação na vazão. O espectro de RF (rádio frequência) é fiscalizado e controlado por órgãos governamentais, no entanto as redes sem fio padrão IE...

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Compact Filtenna for WLAN Applications

Abstract This manuscript proposes a Filtenna operating in the frequency range of 5.15-5.35 GHz for possible application in wireless local area network (WLAN). Initially, a monopole antenna consisting of a square loop radiating patch is designed at 5.2 GHz and is integrated into a...

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ESTUDO DE PROPAGAÇÃO EM AMBIENTES FECHADOS PARA O PLANEJAMENTO DE WLANS / INDOOR PROPAGATION STUDIES FOR WLAN PLANNING

Recently, an explosive growth in the use of Wireless Local Area Networks - WLANs, using restricted radiation levels and operating in license exempted frequency bands, has been observed, not only for corporative domestic use but also to provide paid internet access in public envir...

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Effect of Complementary Split Ring Resonator Structure on PIFA Antenna

Abstract This paper proposes a new design of Planar Inverted-F Antenna with complementary split ring resonators (CSRRs). The operating frequency of this antenna is 2.425 GHz for Wireless Local Area Network (WLAN) application. The method is to incorporate a single CSRR cell and a ...

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Miniaturized Triple Wideband CPW-Fed Patch Antenna With a Defected Ground Structure for WLAN/WiMAX Applications

Abstract— A coplanar waveguide (CPW)-fed patch antenna with triple wideband is presented for simultaneously satisfying Wireless Local Area Network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) applications. The proposed antenna mainly consists by three radiat...

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A Compact UWB Monopole Antenna with Rejected WLAN Band using Split-Ring Resonator and Assessed by Analytic Hierarchy Process Method

Abstract The design of a compact microstrip line-fed Ultra-wideband (UWB) monopole antenna with a notched band characteristic is presented in this paper. The rejection frequency band occurs around 5-6 GHz, which is appropriate for wireless local area network (WLAN) applications a...

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A Performance Evaluation of WLAN-Femtocell-LTE beyond the Capacity Crunch. Does Femtocell have to overcome WLAN or can they coexist in HetNets?

Abstract This paper originates from a practical experiment based on Mesh Networks. The promising results obtained from this experiment prompted us to discuss in greater depth whether Wireless Local Area Networks (WLAN) are still useful for current communications. This means that ...

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A Compact Dual-Band Octagonal Slotted Printed Monopole Antenna for WLAN/ WiMAX and UWB Applications

AbstractA compact (20 x 20 mm2 size), coplanar waveguide (CPW) fed, octagonal slotted, dual-band antenna is presented in this paper. The proposed antenna has a simple structure consisting of an octagonal slot, L-shape stub, and a two stepped rectangular patch. The introduction of...

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A Compact Dual-Band CPW-Fed Planar Monopole Antenna for 2.62–2.73 GHz Frequency Band, WiMAX and WLAN Applications

Abstract In this paper, we present a compact and low-profile monopole antenna with a simple structure for the 2.6–2.73 GHz frequency band, the Worldwide Interoperability for Microwave Access (WiMAX) and the Wireless Local Area Network (WLAN) applications. The first configuration ...

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