Navegando por Assunto "Redes sem fio"

Agora exibindo 1 - 5 de 5

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 de predição de perda de propagação e qualidade de vídeo em redes sem fio indoor por meio de redes neurais artificiais
(Universidade Federal do Pará, 2018-02-27) CRUZ, Hugo Alexandre Oliveira da; CAVALCANTE, Gervásio Protásio dos Santos; http://lattes.cnpq.br/2265948982068382
This dissertation presents a methodology that aims to assist the planning of indoor wireless network systems, which require prior knowledge of the environments in which they will be deployed. Thus, accurate signal analysis is necessary by means of a statistical empirical approach, which takes into account some factors that influence the propagation of the indoor signal: architecture of the buildings; arrangement of furniture inside the compartments; numbers of walls and floors of various materials, and the spread of radio waves. The methodology adopted is based on measurements with a cross-layer approach, which demonstrates the impact of the physical layer in relation to the application layer, in order to predict the behavior of the Quality of Experience (QoE) metric, called Peak signal- to-noise ratio (PSNR), in 4K video streams on 802.11ac wireless networks in the indoor environment. In order to do so, measurements were performed, which demonstrate how the signal / video degrades in the studied environment. It is possible to model this degradation by means of a computational intelligence technique, called Artificial Neural Networks (RNA), in which input parameters are inserted as, for example, the distance from the transmitter to the receiver and the number of walls crossed in order to predict loss of propagation and loss of PSNR. In order to evaluate the predictive capacity of the proposed methods, the values of the Root Mean Sqare (RMS) errors between the measured and predicted data were obtained by the prediction methods loss of propagation and loss of PSNR, with respective values of 2.17 dB and 2.81 dB.
Acesso aberto (Open Access)
Métricas de QoE/QoS de vídeo em redes sem fio para auxilio ao planejamento de ambientes indoor utilizando uma abordagem bayesiana
(Universidade Federal do Pará, 2015-03-30) CARVALHO, André Augusto Pacheco de; CAVALCANTE, Gervásio Protásio dos Santos; http://lattes.cnpq.br/2265948982068382
The evolution of applications on wireless networks has grown in recent years, due to the increased number of smartphone users, tablets and others. The availability of demanding services such as video transmission, affects Quality Experience (QoE) and Quality of Service (QoS) provided to domestic users and trade, this had stimulated the study of new resource management techniques networks, aiming to provide quality services to a customer each increasingly demanding. This thesis presents a methodology Intelligence Artificial using a Bayesian network with a hybrid evaluation strategy analyzing the behavior metrics QoE and QoS in the LAN network design wireless. The diversity of the place of Measurements chosen compound materials such as brick, glass, wood and concrete. It was necessary first to map all the points to be measured before and after deliberately placing each barrier outdated the signal. Metrics as level Receiver Signal Strength Intensity signal (RSSI) Jitter, delay end to end network for the video transmission, PeakSignal-to-NoiseRatio (PSNR) and Structural Similarity (SSIM) were collected during the Measurements. And using the Bayesian Network inferences were made for each metric and could not find satisfactory results for the proposed solution assist the wireless network planning in indoor environments. Enabling demonstrate that up to 10 meters away from the transmitter, the signal has its best power, and delay metrics in order to have more than 65% probability that the lower delay range and following this optimum performance the Jitter has more than 65% probability in this lower range. And the QE metrics, PSRN and SSIM have a similar behavior and has more than 80% probability of getting your greater value, and consequently the video has its best reception. These results show that does not preclude the use of this proposal in other situations.
Acesso aberto (Open Access)
Planejamento de rede LTE utilizando aproximação híbrida de modelo empírico outdoor: medição e técnica de algoritmo genético
(Universidade Federal do Pará, 2015-03-20) PINHEIRO, Márcio Rodrigues; CAVALCANTE, Gervásio Protásio dos Santos; http://lattes.cnpq.br/2265948982068382
Currently, it is visible the growing number of mobile communications networks in the telecommunications scenario. In order to supply the demands of the most demanding users of mobile services with data transmission rates increasing constantly are developed by companies linked to the telecommunications industry, new technologies to keep up with these demands. As 2G and 3G networks can no longer bear the demands of current users because they can not provide quality services to customers due to limitations of data transfer rate. It was then developed, the LTE system (Long Term Evolution), which has become one of the most promising solutions to meet the growing demand of the telecommunications sector. In the LTE system, also called 4G is implemented efficiently on the network, various simulation tools to cover prediction has been developed. Great efforts have been invested in the development of these tools, in order that the predicted values are the closest possible to reality, making it indispensable in planning the LTE network. In this context, this paper is intended to study and optimization of outdoor propagation loss models available in the literature, operating in the 2.6GHz frequency range, in order to provide a propagation loss prediction more accurate the study environment. Therefore, signal measurements campaigns were held in Bethlehem in order to compare how satisfactory are the adjustments of the models of propagation loss with the signal loss measured in realized routes. It was observed that in certain measurements, models of propagation loss, did not show similar curves to that measured on the routes taken, showing high prediction error. Thus, optimization technique was used for all prediction models based on a Genetic Algorithm (GA). Through this technique, it was possible to achieve a significant improvement of the models studied compared the losses encountered on the routes taken, thus contributing to more efficient planning for networks operating in the LTE 2.6GHz range.
Acesso aberto (Open Access)
Planejamento de redes de comunicação sem fio para ambientes indoor considerando aplicações multimídia: abordagem híbrida - simulação e medição
(Universidade Federal do Pará, 2014-08-29) BRAGA, Allan dos Santos; FRAIHA, Simone da Graça de Castro; http://lattes.cnpq.br/6398509825377181; CAVALCANTE, Gervásio Protásio dos Santos; http://lattes.cnpq.br/2265948982068382
Wireless technologies have evolved rapidly in recent decades. It is an efficient alternative to transmit information, whether data, voice, video and other network services. Knowledge of the propagation process of this information in different environments is a factor of great importance for the planning and development of wireless communications systems. Because of the rapid progress and popularization of these networks, the services offered become more complex and therefore need requirements for qualities that are offered to the end user in a satisfactory manner. Because of this, it is necessary to designers of these systems, a methodology that provides a better assessment of the indoor environment. This assessment is made by analyzing the coverage area and the behavior of the metrics of multimedia services anywhere in the environment that is receiving the service. The work in this study intends to evaluate a methodology for the prediction of quality metrics experience. For this, measurements of video streaming campaigns were conducted in a wireless network and network parameters (packet/frames jitter and packet/frames loss) and some quality parameters of experience (PSNR, VQM and SSIM) were evaluated. The results showed good agreement with literature data and with measurements.