Mobile Cellular Systems
Mostrando 13-24 de 47 artigos, teses e dissertações.
-
13. AvaliaÃÃo de dependabilidade de sistemas com mecanismos tolerantes a falha: desenvolvimento de um mÃtodo hÃbrido baseado em EDSPN e diagrama de blocos
In current days, we observe a vertiginous advance of technology and a larger dependence of the society on computational systems. A massive use of computerized devices, fixed and mobile, inside a concept of ubiquitous computation, and the increasing pervasiveness of computers and services networks, have been turning systems extremely complex and dynamic. This
Publicado em: 2007
-
14. Usability study of mobile phones / Estudo de usabilidade em telefones celulares
lt is happening a fast convergence of technologies regarding mobile phones. The first mobile phone generation was developed to satisfy the users to make and receive calls similarly to fixed phones. However, new functionalities such as messaging, multimedia, internet connection, sound player, video, camera, Bluetooth are being added into these devices, which
Publicado em: 2006
-
15. TÉCNICAS PARA A MELHORIA DE DESEMPENHO DA TRANSMISSÃO DE VOZ NO SISTEMA UMTS / TECHNIQUES FOR VOICE TRANSMISSION IMPROVEMENT IN UMTS SYSTEMS
With the advent of multimedia traffic, Third Generation mobile systems were introduced, with the UMTS as the most promissor candidate. In consonance with the global trend of utilization of the IP technology in fixed networks, the UMTS developers decided to incorporate this protocol, which presents more facilities for the introduction of new services. Therefo
Publicado em: 2006
-
16. 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
-
17. Application of artificial intelligence techniques for dynamic channel allocation on wireless networks. / Aplicação de técnicas de inteligência artificial na alocação dinâmica de canais em redes sem fio.
In the last years, mobile networks became more important for communication systems infrastructure. One area of great growth is mobile computation, which is performed through radio signals. The amount of available channels rarely is enough to attend the increasing demand. This work presents a solution for the channel allocation topic, a challenging topic in
Publicado em: 2006
-
18. Avaliação dos modelos de predição de propagação para telefonia móvel celular na cidade do Natal
The development of wireless telecommunication in the last years has been great. It has been taking academics to conceive new ideas and techniques. Their aims are to increase the capacity and the quality of the systems services. Cells that are smaller every time, frequencies that are every time higher and environments that get more and more complex, all those
Publicado em: 2006
-
19. 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
-
20. Selection algorithm of spreading sequences for CDMA systems with space-time coding and antenna array / Algoritmo de escolha de sequencias de espalhamento em sistemas CDMA com codificação espaço-temporal e arranjo de antenas
The performance of mobile communication systems based on the CDMA technique is limited by interference. In this thesis, we propose a selection algorithm of spreading sequences with fixed length for interference mitigation on CDMA systems over frequency-selective fading channels, that is based on the minimization of the overall mean bit error probability of t
Publicado em: 2005
-
21. Performance analysis of 2G, 2.5G and 3G cellular mobile systems / Analise de desempenho dos sistemas moveis celulares 2G, 2,5G e 3G
Este trabalho de tese estuda e analisa o desempenho dos sistemas móveis celulares GSM de segunda geração (2G), GPRS de segunda geração intermediária (2,5G) e CDMA2000 de terceira geração (3G). Na primeira parte deste trabalho de tese são avaliadas estratégias de compartilhamento dos canais de comunicação utilizados pelos sistemas GSM e GPRS, em b
Publicado em: 2005
-
22. RADIO-LOCALIZAÇÃO EM SISTEMAS DE TECNOLOGIA TDMA / RADIOLOCATION IN SYSTEMS OF TECHNOLOGY TDMA
Este trabalho é um estudo sobre radio-localização de terminais móveis em sistemas de tecnologia TDMA. Pela legislação americana e também pela extrema competitividade entre operadores de telefonia na conquista de novos mercados e de provisão de novos serviços, técnicas que permitam a localização do terminal móvel têm sido intensamente pesquisada
Publicado em: 2004
-
23. ESTUDO E SIMULAÇÃO DE TÉCNICAS DE LOCALIZAÇÃO DE TERMINAIS EM AMBIENTES MICROCELULARES / INVESTIGATION AND SIMULATION OF TERMINAL LOCATION TECHNIQUESIN MICROCELLULAR SYSTEMS
The location of mobile terminals in mobile cellular systems has been receiving increasing attention in the last few years. This interest in focused not only in security aspects but also in the development of new services for commercial application. In this Dissertation a simulation environment for mobile stations location in microcellular systems was develop
Publicado em: 2003
-
24. Estudo do efeito de dipolos em arranjos de antenas adaptativas de sistemas de comunicação DS-CDMA
This master dissertation introduces a study about some aspects that determine the aplication of adaptative arrays in DS-CDMA cellular systems. Some basics concepts and your evolution in the time about celular systems was detailed here, meanly the CDMA tecnique, specialy about spread-codes and funtionaly principies. Since this, the mobile radio enviroment, wi
Publicado em: 2003