Navegando por Orientadores "CASTRO, Agostinho Luiz da Silva"

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Acesso aberto (Open Access)
Desenvolvimento, implementação e testes de um sistema de comunicação sem fio heterogêneo para acesso à serviços: aplicações na telemedicina e domótica
(Universidade Federal do Pará, 2011-01-31) SATO, Roberto Masanori Vale; CASTRO, Agostinho Luiz da Silva; http://lattes.cnpq.br/2798180168487751
In the last 20 years, economy and technology have evolved in many directions and into new areas. Many of these developments have created opportunities that are being considered in the conception of future communication networks. These new possibilities are related to, specially, use the internet to access services and include: mobility, low cost technologies, growth and jobs (over the Internet it is possible to participate in each business process and production) services, education (opportunity for people to grow and thrive), entertainment (virtual worlds for entertainment, shopping and games), a high traffic volume (text, voice, images, video). As a result, the Internet has become, like electricity or water, a public good. With almost 2 billion of users (about 28% of world population), the Internet is becoming, increasingly, a pervasive infrastructure providing anywhere and anytime connectivity and services. This world of the Internet current is the result of successive changes that have occurred since its inception and became the communications infrastructure of critical importance. In terms of communication technologies, mobile wireless systems have a special place because of its exceptional propagation in the last decade and, along with the Internet, has allowed the emergence of smart devices, the introduction of new innovative services and demand for an environment that supports innovation and creativity. However, the various network standards to support, mainly to access to last mile are disadvantages to the user's perspective, because it has to enable these networks (to contract the services) and often to have specific terminals to access them. The idea of a single standard for these networks did not achieve satisfactory results and a solution points for the integration of these networks to provide unique and transparent access to the user. This paper therefore presents an embedded solution for integrating wireless communications standards such heterogeneous IEEE 802.15.4 ZigBee, IEEE 802.20 GSM / GPRS and Wi-Fi IEEE 802.2. This heterogeneity of wireless technologies enables a user moving through your local or remote terminal access applications and services in the transparent way. Performance evaluation of the solution was performed using two types of services: home automation and telemedicine. The results indicated that the proposed solution can integrate and provide services with safety and reliability.
Acesso aberto (Open Access)
Metodologia para a medição de parâmetros relacionados com a qualificação do enlace digital do assinante
(Universidade Federal do Pará, 2007-05-25) BRITO JÚNIOR, Edson; CASTRO, Agostinho Luiz da Silva
The present work is related to SELT tests by proposing a methodology for measuring the main parameters related to the loop qualification. For the proposed methodology, some important procedures should be followed in order to provide trust measures such as: appropriate selection of the equipments/devices for the measurements, appropriate choice of the calibration process for the measurements and a statistical treatment of the measurements of the parameters which are Input Impedance, Transfer Function and Scattering Parameter. The present work defines such procedures. For validation of the methodology, some studies of cases were accomplished considering two situations: all of the procedures of measuring were made according to a proposed methodology and, the second case; the measurements made did not follow the proposed procedures. Additionally, in order to prove the applicability of the methodology a comparison evaluation was carried out between the measured data and some theoretical models used as references. In both cases (application of the proposed methodology and in the comparison evaluation) the results showed the applicability of methodology. The data were reliable and coherent with the expected values and theory.