Encontrados 13 documentos, a visualizar página 1 de 2
Electronic Circuits for Wireless Optical LANs - I
Rui L. Aguiar; António Tavares; José Luis Cura; Eduardo de Vasconcelos; Luis Nero Alves; Rui Valadas; Dinis M. SantosThis is the first of two papers discussing practical issues and results on the implementation of low-cost transceivers for several wireless optical LANs, covering most physical layer elements.Target optical LANs under consideration have bit-rates varying between 4Mbps and 25Mbps, and input photodiode capacitance may vary between 10pF and 50pF. PPM modulation, either in a 4-PPM or 1...
Electronic Circuits for Wireless Optical LANs - II
Rui L. Aguiar; António Tavares; José Luis Cura; Eduardo de Vasconcelos; Luis Nero Alves; Rui Valadas; Dinis M. SantosThis is the second of two papers discussing practical issues and results on the implementation of low-cost transceivers for several wireless optical LANs, covering most physical layer elements.Target optical LANs under consideration have bit-rates varying between 4Mbps and 25Mbps, and input photodiode capacitance may vary between 10pF and 50pF. PPM modulation, either in a 4-PPM or ...
A CMOS Signal to Noise Measurement Circuit for Infrared Sectored Receivers
Luís Nero Alves; Rui L. Aguiar; Dinis M. SantosThis paper describes a circuit able to measure Signal to Noise ratios developed for Infrared applications.The Signal to Noise ratio is of major importance in IR Sectored Receivers because it provides the basis of selection or combining of signals coming from different optical sectors. This circuit estimates the ratio of the average optical signal sensed in the photo-detector and the ave...
Utilização de IEEE 802.21 em Handovers Controlados por Rede
Daniel Corujo; Rui L. AguiarThis paper describes and evaluates the application of the IEEE 802.21 standard to an heterogeneous networksIP mobility environment, where handovers are networkcontrolled.The mobility management complexity, increased by the different technologies the terminal is able to connect to,requires the interaction of entities processing information pertaining to the link devices at the terminal (detected links and receiv...
QoS in 4G scenarios using NSIS protocol
Fábio Ferreira; Susana Sargento; Rui L. AguiarThis paper presents quality of service mechanisms, based on the NSIS (Next Steps In Signaling) protocol. For that, it was implemented a testbed with NSIS running through IPv6. The network’s QoS was measured by the number of drops, for each flow (either QoS or Best Effort traffic), occurred in routers. The first experiment shows the captured packets during a node association and request for QoS, namely a G...
Supporting Mobility Mechanisms in NovelContent Centric Networks
Daniel Corujo; Rui L. AguiarThere is a large set of efforts on the definition of new Internet architectures. One of the currently more relevant is the CCN, content-centric networking, architectural concept. This type of architectures is focused on file transferral and fail to address real time multimediacommunications in mobile environments. This paper discusses the mobility mechanisms to improve the design of CCNs for interactive mobile ...
Demonstrador de Redes Heterogéneas suportando Mobilidade
Diogo Gomes; Nuno Duarte; Nuno João Sénica; Rui L. AguiarA demonstrator of heterogeneous networking, based on the European Project Moby Dick, is here presented. The demonstrator supports quality of service, mobility and integrated authentication. The paper discusses different aspects of the implementation of the demonstrator, as well as some packages of software developed. The paper further presents some tests performed on the demonstrat...
Controlo de elementos de rede para suporte de Qualidade de Serviço: reconfigura...
Luis Sousa; Nelson Santiago; Rui L. AguiarProviding Quality of Service in telecommunication networks covers multiple aspects, including the specific support provided by the equipments.This paper analyses the behavior of CISCO equipments and Linux-based routers in high mobility environments. Weidentify aspects relevant to the reconfiguration of differentiated services structures, in order to minimize the associated reconfigurati...
Implementing Charging in Mobile Ad Hoc Networks
João Girão; João Paulo Barraca; Bernd Lamparter; Dirk Westhoff; Rui L. AguiarIn order to keep up with new networking needs, it becomes necessary to adopt mechanisms for charging network usage in a universal way. The Secure Charging Protocol (SCP) aims at answering this complex authentication, authorization, accounting and charging (AAAC) problem, and provides a view based on a different business model, one that has been adjusted to cope with technologi...
Sistemas de Transmissão/Recepção sem Fios por Raios Infravermelhos
Rui S. R. Almeida; José L. J. F. Santo; Rui L. Aguiar; António M. R. TavaresThis paper describes the results obtained in the characterisation, optimisation and test, of two wirelessinfrared communication systems. Although both systems arebased on the same technology they are used on differentapplications.On the first part of this paper an wireless optical indoorcommunication system, that uses angle diversity techniqueson the reception is presented. This optical receiver wasdevelop...
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