767 resultados para WIRELESS NETWORKING


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The optimization of the pilot overhead in wireless fading channels is investigated, and the dependence of this overhead on various system parameters of interest (e.g., fading rate, signal-to-noise ratio) is quantified. The achievable pilot-based spectral efficiency is expanded with respect to the fading rate about the no-fading point, which leads to an accurate order expansion for the pilot overhead. This expansion identifies that the pilot overhead, as well as the spectral efficiency penalty with respect to a reference system with genie-aided CSI (channel state information) at the receiver, depend on the square root of the normalized Doppler frequency. It is also shown that the widely-usedblock fading model is a special case of more accurate continuous fading models in terms of the achievable pilot-based spectral efficiency. Furthermore, it is established that the overhead optimization for multiantenna systems is effectively the same as for single-antenna systems with thenormalized Doppler frequency multiplied by the number of transmit antennas.

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The purpose of this paper is to examine (1) some of the models commonly used to represent fading,and (2) the information-theoretic metrics most commonly used to evaluate performance over those models. We raise the question of whether these models and metrics remain adequate in light of the advances that wireless systems haveundergone over the last two decades. Weaknesses are pointedout, and ideas on possible fixes are put forth.

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Audit report on the Wireless E911 Emergency Communication Fund of the Iowa Homeland Security and Emergency Management Division of the Iowa Department of Public Defense for the year ended June 30, 2006

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O relatório apresentado é a base do estágio curricular do curso de Tecnologia de Informação e Comunicação na Universidade de Cabo Verde. Este projecto tem por objectivo apresentar e descrever as actividades de estágio desenvolvidas no Serviço Técnico da Uni-CV, no Campus do Palmarejo, no período compreendido entre 13 de Maio a 28 de Agosto de 2009. O projecto teve como resultado a integração de rede sem fios no servidor Radius, onde o acesso à rede sem fios é feito mediante a autenticação integrado na active directory; Para desenvolvimento deste projecto passamos pelas seguintes fases: Instalação de Windows server 2003; Instalação do active directory; Criação do Utilizador; Adicionar o utilizador ao grupo; Integração de servidor RADIUS no Windows server 2003; Instalação da CA, Instalação de IAS , Configuração do RADIUS; Configuração do acess Point; Configuração do Cliente Windows XP

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Audit report on the Wireless E911 Emergency Communication Fund of the Iowa Homeland Security and Emergency Management Division of the Iowa Department of Public Defense for the year ended June 30, 2007

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Audit report on the Wireless E911 Emergency Communication Fund of the Iowa Homeland Security and Emergency Management Division of the Iowa Department of Public Defense for the year ended June 30, 2008

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Tripping is considered a major cause of fall in older people. Therefore, foot clearance (i.e., height of the foot above ground during swing phase) could be a key factor to better understand the complex relationship between gait and falls. This paper presents a new method to estimate clearance using a foot-worn and wireless inertial sensor system. The method relies on the computation of foot orientation and trajectory from sensors signal data fusion, combined with the temporal detection of toe-off and heel-strike events. Based on a kinematic model that automatically estimates sensor position relative to the foot, heel and toe trajectories are estimated. 2-D and 3-D models are presented with different solving approaches, and validated against an optical motion capture system on 12 healthy adults performing short walking trials at self-selected, slow, and fast speed. Parameters corresponding to local minimum and maximum of heel and toe clearance were extracted and showed accuracy ± precision of 4.1 ± 2.3 cm for maximal heel clearance and 1.3 ± 0.9 cm for minimal toe clearance compared to the reference. The system is lightweight, wireless, easy to wear and to use, and provide a new and useful tool for routine clinical assessment of gait outside a dedicated laboratory.

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Audit report on the Wireless E911 Emergency Communication Fund of the Iowa Homeland Security and Emergency Management Division of the Iowa Department of Public Defense for the year ended June 30, 2009

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The new Swiss federal law on organ and transplantation strengthens the responsibilities of the intensive care units. In Italian and French speaking parts of Switzerland, the Programme Latin pour le Don d'Organe (PLDO) has been launched to foster a wider collaboration between intensivists and donation coordinators. The PLDO aims at optimising knowledge and expertise in organ donation through improvements in identification, notification and management of organ donors and their next of kin. The PLDO dispenses education to all professionals involved. Such organisation should allow increasing the number of organs available, while improving healthcare professionals experience and next of kin emotion throughout the donation process.

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It is widely known that informal contacts and networks constitute a major advantage when searching for a job. Unemployed people are likely to benefit from such informal contacts, but building and sustaining a network can be particularly difficult when out of employment. Interventions that allow unemployed people to effectively strengthen their networking capability could as a result be promising. Against this background, this article provides some hints in relation to the direction that such interventions could take. First, on the basis of data collected on a sample of 4,600 newly-unemployed people in the Swiss Canton of Vaud, it looks at the factors that influence jobseekers' decisions to turn to informal contacts for their job search. The article shows that many unemployed people are not making use of their network because they are unaware of the importance of this method. Second, it presents an impact analysis of an innovative intervention designed to raise awareness of the importance of networks which is tested in a randomized controlled trial setting.

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Audit report on the Wireless E911 Emergency Communications Fund of the Iowa Homeland Security and Emergency Management Division of the Iowa Department of Public Defense for the year ended June 30, 2010

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Selostus: Kestävän kehityksen integroidun tutkimuksen ja verkostotalouden teorian tutkimusmenetelmälliset ongelmat

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Audit report on the Wireless E911 Emergency Communications Fund of the Iowa Homeland Security and Emergency Management Division of the Iowa Department of Public Defense for the year ended June 30, 2011

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Purpose: In vitro studies in porcine eyes have demonstrated a good correlation between induced intraocular pressure variations and corneal curvature changes, using a contact lens with an embedded microfabricated strain gauge. Continuous 24 hour-intraocular pressure (IOP) monitoring to detect large diurnal fluctuation is currently an unmet clinical need. The aims of this study is to evaluate precision of signal transmission and biocompatibility of 24 hour contact lens sensor wear (SENSIMED Triggerfish®) in humans. Methods: After full eye examination in 10 healthy volunteers, a 8.7 mm radius contact lens sensor and an orbital bandage containing a loop antenna were applied and connected to a portable recorder. Best corrected visual acuity and position, lubrication status and mobility of the sensor were assessed after 5 and 30 minutes, 4, 7 and 24 hours. Subjective comfort was scored and activities documented in a logbook. After sensor removal full eye examination was repeated, and the registration signal studied. Results: The comfort score was high and did not fluctuate significantly, except at the 7 hour-visit. The mobility of the contact lens was minimal but its lubrication remained good. Best corrected visual acuity was significantly reduced during the sensor wear and immediately after its removal. Three patients developed mild corneal staining. In all but one participant we obtained a registration IOP curve with visible ocular pulse amplitude. Conclusions: This 24 hour-trial confirmed the functionality and biocompatibility of SENSIMED Triggerfish® wireless contact lens sensor for IOP-fluctuation monitoring in volunteers. Further studies with a range of different contact lens sensor radii are indicated.

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Audit report on the Wireless E911 Emergency Communications Fund of the Iowa Homeland Security and Emergency Management Division of the Iowa Department of Public Defense for the year ended June 30, 2012