801 resultados para wireless telecommunication


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Using Wireless Sensor Networks (WSNs) in healthcare systems has had a lot of attention in recent years. In much of this research tasks like sensor data processing, health states decision making and emergency message sending are done by a remote server. Many patients with lots of sensor data consume a great deal of communication resources, bring a burden to the remote server and delay the decision time and notification time. A healthcare application for elderly people using WSN has been simulated in this paper. A WSN designed for the proposed healthcare application needs efficient Medium Access Control (MAC) and routing protocols to provide a guarantee for the reliability of the data delivered from the patients to the medical centre. Based on these requirements, the GinMAC protocol including a mobility module has been chosen, to provide the required performance such as reliability for data delivery and energy saving. Simulation results show that this modification to GinMAC can offer the required performance for the proposed healthcare application.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Using Wireless Sensor Networks (WSNs) in healthcare systems has had a lot of attention in recent years. In much of this research tasks like sensor data processing, health states decision making and emergency message sending are done by a remote server. Many patients with lots of sensor data consume a great deal of communication resources, bring a burden to the remote server and delay the decision time and notification time. A healthcare application for elderly people using WSN has been simulated in this paper. A WSN designed for the proposed healthcare application needs efficient MAC and routing protocols to provide a guarantee for the reliability of the data delivered from the patients to the medical centre. Based on these requirements, the GinMAC protocol including a mobility module has been chosen, to provide the required performance such as reliability for data delivery and energy saving. Simulation results show that this modification to GinMAC can offer the required performance for the proposed healthcare application.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Wireless Senor Networks(WSNs) detect events using one or more sensors, then collect data from detected events using these sensors. This data is aggregated and forwarded to a base station(sink) through wireless communication to provide the required operations. Different kinds of MAC and routing protocols need to be designed for WSN in order to guarantee data delivery from the source nodes to the sink. Some of the proposed MAC protocols for WSN with their techniques, advantages and disadvantages in the terms of their suitability for real time applications are discussed in this paper. We have concluded that most of these protocols can not be applied to real time applications without improvement

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Health monitoring technologies such as Body Area Network (BAN) systems has gathered a lot of attention during the past few years. Largely encouraged by the rapid increase in the cost of healthcare services and driven by the latest technological advances in Micro-Electro-Mechanical Systems (MEMS) and wireless communications. BAN technology comprises of a network of body worn or implanted sensors that continuously capture and measure the vital parameters such as heart rate, blood pressure, glucose levels and movement. The collected data must be transferred to a local base station in order to be further processed. Thus, wireless connectivity plays a vital role in such systems. However, wireless connectivity comes at a cost of increased power usage, mainly due to the high energy consumption during data transmission. Unfortunately, battery-operated devices are unable to operate for ultra-long duration of time and are expected to be recharged or replaced once they run out of energy. This is not a simple task especially in the case of implanted devices such as pacemakers. Therefore, prolonging the network lifetime in BAN systems is one of the greatest challenges. In order to achieve this goal, BAN systems take advantage of low-power in-body and on-body/off-body wireless communication technologies. This paper compares some of the existing and emerging low-power communication protocols that can potentially be employed to support the rapid development and deployment of BAN systems.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The efficiency of a Wireless Power Transfer (WPT) system is greatly dependent on both the geometry and operating frequency of the transmitting and receiving structures. By using Coupled Mode Theory (CMT), the figure of merit is calculated for resonantly-coupled loop and dipole systems. An in-depth analysis of the figure of merit is performed with respect to the key geometric parameters of the loops and dipoles, along with the resonant frequency, in order to identify the key relationships leading to high-efficiency WPT. For systems consisting of two identical single-turn loops, it is shown that the choice of both the loop radius and resonant frequency are essential in achieving high-efficiency WPT. For the dipole geometries studied, it is shown that the choice of length is largely irrelevant and that as a result of their capacitive nature, low-MHz frequency dipoles are able to produce significantly higher figures of merit than those of the loops considered. The results of the figure of merit analysis are used to propose and subsequently compare two mid-range loop and dipole WPT systems of equal size and operating frequency, where it is shown that the dipole system is able to achieve higher efficiencies than the loop system of the distance range examined.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper presents a study on reduction of energy consumption in buildings through behaviour change informed by wireless monitoring systems for energy, environmental conditions and people positions. A key part to the Wi-Be system is the ability to accurately attribute energy usage behaviour to individuals, so they can be targeted with specific feedback tailored to their preferences. The use of wireless technologies for indoor positioning was investigated to ascertain the difficulties in deployment and potential benefits. The research to date has demonstrated the effectiveness of highly disaggregated personal-level data for developing insights into people’s energy behaviour and identifying significant energy saving opportunities (up to 77% in specific areas). Behavioural research addressed social issues such as privacy, which could affect the deployment of the system. Radio-frequency research into less intrusive technologies indicates that received-signal-strength-indicator-based systems should be able to detect the presence of a human body, though further work would be needed in both social and engineering areas.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Wireless Sensor Networks (WSNs) have been an exciting topic in recent years. The services offered by a WSN can be classified into three major categories: monitoring, alerting, and information on demand. WSNs have been used for a variety of applications related to the environment (agriculture, water and forest fire detection), the military, buildings, health (elderly people and home monitoring), disaster relief, and area or industrial monitoring. In most WSNs tasks like processing the sensed data, making decisions and generating emergency messages are carried out by a remote server, hence the need for efficient means of transferring data across the network. Because of the range of applications and types of WSN there is a need for different kinds of MAC and routing protocols in order to guarantee delivery of data from the source nodes to the server (or sink). In order to minimize energy consumption and increase performance in areas such as reliability of data delivery, extensive research has been conducted and documented in the literature on designing energy efficient protocols for each individual layer. The most common way to conserve energy in WSNs involves using the MAC layer to put the transceiver and the processor of the sensor node into a low power, sleep state when they are not being used. Hence the energy wasted due to collisions, overhearing and idle listening is reduced. As a result of this strategy for saving energy, the routing protocols need new solutions that take into account the sleep state of some nodes, and which also enable the lifetime of the entire network to be increased by distributing energy usage between nodes over time. This could mean that a combined MAC and routing protocol could significantly improve WSNs because the interaction between the MAC and network layers lets nodes be active at the same time in order to deal with data transmission. In the research presented in this thesis, a cross-layer protocol based on MAC and routing protocols was designed in order to improve the capability of WSNs for a range of different applications. Simulation results, based on a range of realistic scenarios, show that these new protocols improve WSNs by reducing their energy consumption as well as enabling them to support mobile nodes, where necessary. A number of conference and journal papers have been published to disseminate these results for a range of applications.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Network diagnosis in Wireless Sensor Networks (WSNs) is a difficult task due to their improvisational nature, invisibility of internal running status, and particularly since the network structure can frequently change due to link failure. To solve this problem, we propose a Mobile Sink (MS) based distributed fault diagnosis algorithm for WSNs. An MS, or mobile fault detector is usually a mobile robot or vehicle equipped with a wireless transceiver that performs the task of a mobile base station while also diagnosing the hardware and software status of deployed network sensors. Our MS mobile fault detector moves through the network area polling each static sensor node to diagnose the hardware and software status of nearby sensor nodes using only single hop communication. Therefore, the fault detection accuracy and functionality of the network is significantly increased. In order to maintain an excellent Quality of Service (QoS), we employ an optimal fault diagnosis tour planning algorithm. In addition to saving energy and time, the tour planning algorithm excludes faulty sensor nodes from the next diagnosis tour. We demonstrate the effectiveness of the proposed algorithms through simulation and real life experimental results.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The progress in wearable and implanted health monitoring technologies has strong potential to alter the future of healthcare services by enabling ubiquitous monitoring of patients. A typical health monitoring system consists of a network of wearable or implanted sensors that constantly monitor physiological parameters. Collected data are relayed using existing wireless communication protocols to the base station for additional processing. This article provides researchers with information to compare the existing low-power communication technologies that can potentially support the rapid development and deployment of WBAN systems, and mainly focuses on remote monitoring of elderly or chronically ill patients in residential environments.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

With the rapid development of telecommunication industry, the IP multimedia Subsystem (IMS) could very well be the panacea for most telecom operators. It is originally defined as the core network for 3G mobile systems by the 3rd Generation Partnership Project (3GPP), the more recent development is merging between fixed line network and wireless networkd This report researchs the characteristic of the IMS data and proposes an IMS characterization analysis. We captured the IMS traffic data with 10 tousands users for about 41 hours. By analyzing the characteristics of the IMS, we know that the most important application in the IMS is VoIP call. Then we use the tool designed by Tsinghua University & Ericsson Company to recognize the data, and the results we got can be used to build the traffic models. From the results of the traffic models, I will get some reasons and conclusion. The traffic model gives out the types of session and types of VoIP call. I bring into a concept—busy hour. This concept is very important because it can help us to know which period is the peak of the VoIP call. The busy hour is from 10:00 to 11:00 in the morning. I also bring into another concept—connection ratio. This concept is significant because it can evaluate whether the VoIP call is good when it use IMS network. By comparing the traffic model with other one’s models, we found the different results from them, both the accuracy and the busy hour. From the contract, we got the advantages of our traffic models.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Este trabalho apresenta, inicialmente, uma análise comparativa detalhada dos dois padrões, IEEE 802.11a e IEEE802.11b, que foram apresentados recentemente pelo IEEE na área de redes sem fio (wireless). São apresentadas as principais diferenças tecnológicas dos dois padrões, no que se refere, principalmente, à arquitetura, funções de controle, segurança, desempenho e custo de implementação destas duas tecnologias de redes wireless. São avaliados também os aspectos de interoperabilidade, quando estas redes são integradas em redes corporativas fixas, que são baseadas, principalmente, em redes Ethernet, tradicionalmente usadas em redes corporativas. São considerados também, aspectos de custo e flexibilidade de aplicação das duas tecnologias e mostram-se como estas diferenças devem ser levadas em conta em aplicações típicas de um ambiente corporativo. Finalmente, apresenta-se também, como estudo de caso, uma análise focalizada principalmente na integração da tecnologia wireless em aplicações típicas de uma grande empresa local. Consideram-se as vantagens e desvantagens de ambas as tecnologias, como solução para algumas aplicações típicas encontradas nesta empresa, e justifica-se a escolha da solução que foi adotada. Conclui-se com algumas projeções quanto ao futuro da tecnologia wireless no ambiente público e corporativo.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Internet Telephony (VoIP) is changing the telecommunication industry. Oftentimes free, VoIP is becoming more and more popular amongst users. Large software companies have entered the market and heavily invest into it. In 2011, for instance, Microsoft bought Skype for 8.5bn USD. This trend increasingly impacts the incumbent telecommunication operators. They see their main source of revenue – classic telephony – under siege and disappear. The thesis at hand develops a most-likely scenario in order to determine how VoIP is evolving further and it predicts, based on a ten-year forecast, the impact it will have on the players in the telecommunication industry.The paper presents a model combining Rogers’ diffusion and Christensen’s innovation research. The model has the goal of explaining the past evolution of VoIP and to isolate the factors that determine the further diffusion of the innovation. Interviews with industry experts serve to assess how the identified factors are evolving.Two propositions are offered. First, VoIP operators are becoming more important in international, corporate, and mobile telephony. End-to-end VoIP (IP2IP) will exhibit strong growth rates and increasingly cannibalize the telephony revenues of the classic operators. Second, fix-net telephony in SMEs and at home will continue to be dominated by the incumbents. Yet, as prices for telephony fall towards zero also they will implement IP2IP in order to save costs. By 2022, up to 90% of the calls will be IP2IP. The author recommends the incumbents and VoIP operators to proactively face the change, to rethink their business strategies, and to even be open for cooperation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

O telefone celular teve uma grande evolução nos últimos anos, o que antes era utilizado exclusivamente para transmissão de voz, hoje tem características avançadíssimas incluindo várias evoluções tecnológicas. Dentro deste aspecto, a inovação que o LTE (Long Term Evolution) vem demonstrando em suas características realmente se destacam em relação as tecnologias que a antecederam e representa grande evolução se comparada com as outras. Foi desenvolvida no âmbito do projeto 3GPP e (3rd Generation Partners Project) promovido pelo Instituto Europeu de Normalização na área de Telecomunicações ETSI (European Telecommunications Standard Institute). As operadoras que demonstram interesse em disponibilizar esta tecnologia buscam introduzir a flexibilidade do LTE para ir ao encontro dos objetivos de suas redes existentes, espectro e negócios para banda larga móvel e serviços multimídia. O LTE promete taxas de download de 326,4Mbps, taxas de upload de 86,4Mbps, RTT ( ROUND TRIP TIME ) menos de 10 mile segundos e raio das células podendo atingir até 100km. O sistema 4G (LTE) é um sistema integrado completamente baseado em IP, que é resultado de tecnologias conectadas por fios e sem fios disponibilizando um custo acessível, atendendo as exigências de uma rede de comunicação (Wireless), serviços de transferência de mensagens multimídias, conversa com vídeo, televisão móvel de alta definição, serviços mínimos como voz e dados entre outras vantagens. Desta forma, este estudo tem por objetivo analisar quais são as oportunidades e os desafios no mercado de telefonia móvel de Telecomunicações ao implantar o sistema de tecnologia LTE demonstrando o benefício dos fabricantes e operadoras no sentido econômico e tecnológico.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

As telecomunicações no mundo têm avançado a passos largos na oferta de novas tecnologias e padrões que viabilizam e flexibilizam a transmissão / recepção de informações entre pessoas e a Internet. Em especial, no que tange à ubiqüidade, o uso de dispositivos de comunicações móveis sem fio, como telefones celulares e PDAs (Personnal Digital Assistant), tem permitido às empresas alcançarem seus clientes a qualquer hora e em qualquer lugar. Muitos padrões de comunicação wireless têm surgido, inicialmente na indústria de telefonia móvel celular e, em seguida, na indústria de computadores e PDAs, habilitando a comunicação wireless de dados em banda larga e o comércio eletrônico móvel (m-commerce). Em especial, o padrão Wi-Fi tem sido difundido mundialmente através da expansão de redes públicas sem fio (PWLANs). Assim, os fabricantes de equipamentos de telecomunicações, as empresas operadoras de serviços de telefonia fixa e móvel e até provedores de acesso à Internet têm manifestado grande interesse nessa área por perceberem novas oportunidades de aumento de receita através da tecnologia Wi-Fi. Todos estes aspectos da recente história do Wi-Fi têm gerado questionamentos quanto a seu futuro sucesso e real geração de vantagem competitiva sustentável, não obstante o volume de negócios relativos a esta tecnologia estar em franco crescimento. Este trabalho propõe-se a analisar o mercado de serviços PWLAN Wi-Fi brasileiro, identificando os principais atores e os modelos de negócio praticados por eles, comparando esses modelos aos modelos identificados por Shubar e Lechner. O estudo propõe-se, também, a avaliar tais empresas e seus respectivos modelos de negócio segundo o framework VRIO desenvolvido por Barney com base na visão estratégica baseada em recursos (RBV- Resource Based View).

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A privatização de uma empresa é uma mudança empresarial disruptiva que geralmente coincide com o fim de uma posição de monopólio e da subsequente entrada num ambiente competitivo. Os desafios que a privatização coloca são tão árduos que eles levam muitas vezes a liderança (leadership) para executar planos ambiciosos de mudança empresarial. No entanto, a literatura mostra que muitos deles falharam. Na verdade, esses planos preveem mudanças bruscas e importantes que tendem a empurrar a empresa privatizada na armadilha de aceleração (acceleration trap). Um tipo de “burnout organizacional” (organizational burnout) onde a exaustão e a resignação da força de trabalho afetam drasticamente o desempenho da empresa. A tese, portanto, focalizou em estudar a ligação entre um processo de privatização e o risco de cair na armadilha de aceleração. Uma investigação preliminar sobre a literatura das mudanças empresariais permitiu a concepção de um quadro preliminar teórico que sugere a existência de dois moderadores (moderators) deste relacionamento entre um processo de privatização e a armadilha de aceleração: um “choque cultural” (cultural clash) e um “fraco clima de liderança transformacional” (weak transformational leadership). Em seguida, um estudo de caso - baseado numa empresa de telecomunicações europeia e conduzido através de uma abordagem metodológico não puramente indutivo (non-purely inductive approach) - confirma, mas também aprofunda a compreensão da ação desses dois moderadores. A respeito do moderador “choque cultural” (cultural clash moderator), a análise de dados do estudo de caso da empresa de telecomunicações europeia mostra a importância exercitado tanto por um “choque de identidade corporativa” (corporate identity conflict) como por um “conflito de identidade gerencial” (management identity conflict). Quanto ao moderador “fraco liderança transformacional”, a análise dos dados destaca o papel da “falta de confiança na nova gerência” (lack of trust in the new management), mas também de “sentido do trabalho” (lack of job sense), principalmente através da perda de “orgulho no trabalho” (loss of proudness). Finalmente, a análise dos dados salienta que a “não aceitação do novo sistema de incentivos” (non-acceptance of the new incentive system) afeta significativamente a relação entre a privatização e a armadilha de aceleração, contribuindo tanto para um “choque cultural” como para um “fraco clima de liderança transformacional”.