Cellular Communications
Mostrando 1-12 de 19 artigos, teses e dissertações.
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1. FD MAC Protocol Design for Co-Existing WLANs in 5G Cellular Networks
Abstract In this paper, we design full-duplex (FD) medium access control (MAC) protocol for co-existing wireless local area networks (WLANs) in 5G cellular networks (WCFD-MAC). Our design considers some significant features of 5G networks, exceptionally, beamforming and FD capabilities at both, the base station and user equipment. FD communications may gener
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2021-03
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2. 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 on the one hand femtocells can be defined as small base stations that use the sa
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2016-12
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3. Segurança em sistemas de comunicação pessoal : um modelo de arquitetura de protocolos para a interconexão de sistemas heterogêneos / Security in personal communications systems. one model of protocol architecture for the interworking of heterogeneous systems
A evolução dos sistemas de comunicação sem fio ou wireless apresentam até agora três gerações em menos de duas décadas. Fazendo parte desta evolução estão os sistemas de telefonia celular e os emergentes Sistemas de Comunicação Pessoal ou PCS (Personal Communications Systems). Este trabalho visa apresentar duas questões importantes na evoluç�
Publicado em: 2010
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4. Estimativa do número de estações de rádio base para a implantação do WIMAX no Distrito Federal
During the past years, the video, voice and data services available in the fixed communications networks have been requested by users in mobility. This fact has motivated the development of technologies that allow traffic of a lot of information in cellular telephone networks. WiMAX e UMTS are technologies that can help the traffic flow. The WiMAX, known as
Publicado em: 2009
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5. EQUALIZAÇÃO DE CANAL EM SISTEMAS COM TRANSMISSÃO EM BLOCOS / CHANNEL EQUALIZATION IN BLOCK TRANSMISSION SYSTEMS
The demand for high rate transmission systems, for example in HDTV, third and fourth generation cellular telephony, DSL and so on, causes the rise of a problem: The multipath communications channel (specially in wireless communications), which leads to intersymbol interference phenomenon (ISI). The present work investigates the performance of single-carrier
Publicado em: 2007
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6. Proposta de um esquema de codificaÃÃo de vÃdeo a baixas taxas de transmissÃo para comunicaÃÃes mÃveis celulares / Proposal for low bit rate video coding for cellular phones communications
Very low bit rate coding below 64 kbit/s will be an important issue in forthcoming visual services such as videophone and multimedia systems. The trend of increasing interest in, and demand for, mobile phone, interactive TV and multimedia services, has led to significant acceleration of video coding research worldwide. This paper introduces and presents simu
Publicado em: 2006
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7. Simulador para servidor habilitador de localizaÃÃo em plataforma LBS
Since XIX centuryâs end, the telephony suffered to constant technological evolution. In the 70âs, a new need was looked for: mobility. So, it began the age of the mobile communications. The increasing integration between cellular systems and computer science made possible the development of new technologies and services to the mobile networks. Currently, t
Publicado em: 2006
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8. Estimação da direção de chegada (DOA) de sinais eletromagnéticos em canais reversos CDMA utilizando antenas inteligentes
The great effort of communications engineers is to create methods that allows improve spectrum usage efficiency, that is a scarce resource. The Code Division Multiple Access (CDMA) and the spatial processing techniques using array of antennas are two enable technologies to achieve this task. In this context, the smart antennas technique can improve the recep
Publicado em: 2006
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9. ExtraÃÃo de pigmentos carotenÃides de resÃduos do processamento do camarÃo branco Litopenaeus vannamei utilizando autÃlise proteolÃtica
Carotenoids consist of the most abundant class of organic pigments in nature. They are present in the photosynthetic organisms, fungi, bacteria, algae and in all classes of animals from protozoa to human. They include an array of substances that present different biological properties such as enhancing immune functions; reduce the risk of developing degenera
Publicado em: 2006
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10. RADIOLOCALIZAÇÃO DE TERMINAIS DE COMUNICAÇÕES MÓVEIS / RADIOLOCATION OF MOBILE COMMUNICATIONS TERMINALS
This work addresses the radiolocation problem of a moving terminal in a cellular mobile communications environment. New alternatives are developed for position estimation, assuming that the Time of Arrival (ToA) measurements obtained from radio link are corrupted by additive noise and have positive mean error during random periods of time due to the non-line
Publicado em: 2004
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11. Adaptative Antennas for Wireless Communications Systems / Antenas Adaptativas para Sistemas de Comunicações Sem Fio
Adaptive antennas is a radiating system that allows a control of the format and the direction of radiation diagram. With this control, they are capable to guide the main lobe of the radiation diagram to the desired signal and to reduce, simultaneously, the influence of the interferences signals. These systems have an accented demand in the technologies 3G an
Publicado em: 2003
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12. DEVELOPMENT OF A SIMULATION TOOL FOR CELLULAR NETWORK PLANNING AND PERFORMANCE EVALUATION BASED ON THE SIGNALING LOAD / DESENVOLVIMENTO DE UMA FERRAMENTA DESIMULAÇÃO PARA PLANEJAMENTO E ANÁLISE DO DESEMPENHO DE REDES CELULARES A PARTIR DA CARGA DE SINALIZAÇÃO GERADA
The advent of second and third generation cellular systems make cellular operators face dramatic increase in the signaling traffic over the fixed part of the mobile network. In spite of this, rare mobile communications service providers are able to forecast the above mention increase and quantify it with reasonable precision. This work describes the developm
Publicado em: 2002