19 documents found, page 1 of 2
ICN as Network Infrastructure for Multi-Sensory Devices: Local Domain Service D...
Quevedo, J.; Guimarães, C.; Ferreira, R.; Corujo, D.; Aguiar, R.L.Information Centric Networking (ICN) is an emerging research topic aiming at shifting the Internet from its current host-centric paradigm towards an approach centred around content, which enables the direct retrieval of information objects in a secure, reliable, scalable, and efficient way. The exposure of ICN to scenarios other than static content distribution is a growing research topic, promising to extend t...
Design, development and performance analysis of DSSS-based transceiver for VLC
Terra, D.; Kumar, N.; Lourenço, N.; Alves, L. N.; Aguiar, R.L.This paper addresses and implements a Direct Sequence Spread Spectrum (DSSS) transceiver for Visible Light Communication (VLC) systems based on FPGA. A transceiver was implemented including a transmitter capable of driving an array of light emitting diodes (LED) and a Pseudo-Noise (PN) matched decorrelator. The receiver architecture uses a discrete FIR correlator for data synchronization and acquisition. In thi...
Visible light communication for intelligent transportation in road safety appli...
Kumar, N.; Terra, D.; Lourenço, N.; Alves, L. N.; Aguiar, R.L.This paper discusses the implementation of a light emitting diode based visible light communication system, for intelligent transportation in road safety applications. The signal processing of both, transmitter and receiver are realized in a field programmable gate array using two Spartan-3E development kits. The implemented modulation scheme is based on direct sequence spread spectrum techniques. The performan...
Design and analysis of the basic parameters for traffic information transmissio...
Kumar, N.; Alves, L. N.; Aguiar, R.L.This paper discusses system design considerations concerning the use of visible light communication (VLC) concepts in road traffic control systems. A simple traffic set-up model has been analyzed in order to optimize various important design parameters. This optimization is based on the gain variation over 100m transmission range. This approach will help to specify the needed gain for the receiver in the comple...
Community Building over Neighborhood Wireless Mesh Networks
Antoniadis, P.; Le Grand, B.; Satsiou, A.; Tassiulas, L.; Aguiar, R.L.; João Barraca; Susana SargentoThe fourth generation (4G) network paradigm has long been sought. A user-centric vision for such "always best connected" next-generation 4G networks is neighborhood wireless mesh networks (WMNs). In this context, the vision for the formation of WMNs reflects the trade-off between the immediate self-interest of the user, and the user's need for social contacts. Notably, users would be required to pool their reso...
General model for the deployment of time-delay elements in transistorized elect...
Alves, L. N.; Barbosa, L.; Aguiar, R.L.This paper presents a general model for the analysis of time-delay contributions due to right half plane (RHP) zeros in circuit's transfer functions. The presence of these RHP zeros is in general associated to Miller capacitances. These can be explored as a means of implementation of delay elements. A general discussion on the usage of these RHP zeros as means of designing usable delay cells is addressed, inclu...
General model for delayed feedback and its application to transimpedance amplif...
Alves, L. N.; Barbosa, L.; Macedo, E.A.L.; Aguiar, R.L.Delays in real systems can be of two types: i) intrinsic delays - due to the physical principles of operation of each electronic device; ii) designed delays - due to extra circuits used to add the desired delay. Previous work established the possibility of achieving bandwidth improvements using small delays inside the feedback loop of feedback amplifiers. The modeling approach followed on these contributions us...
Bandwidth boosting in transimpedance amplifiers for optical LANs, using delayed...
Martins, N.; Barbosa, L.; Alves, L. N.; Aguiar, R.L.Delayed-feedback amplifiers are composed of, a forward gain amplifier, a feedback network and a time-delay element. Recently published results [1] claim the possibility of bandwidth enhancement for this type of systems, simply by a judicious choice of loop-gain, open loop poles and the net time-delay. This paper describes the design steps for a shunt-shunt feedback amplifier with an active delay on the feedback...
On the effect of time delays in negative feedback amplifiers
Alves, L. N.; Aguiar, R.L.Time delays are intrinsic to all existing devices and circuits. For the majority of applications, time delays are so small that their effects can be disregarded. However, when considering feedback amplifiers, depending on open-loop poles and loop gain, the effect of a small time delay inside the feedback path may turn to be of considerable importance. This paper analyzes the frequency response effects associate...
On the usage of delayed-feedback in amplifiers
Alves, L. N.; Aguiar, R.L.Time delays are Intrinsic to all electronic circuits and feedback amplifiers are no exception. The effect of a small time delay inside the feedback path may turn to be of considerable importance. Depending on the open-loop poles, the loop-gain and the time delay, the closed-loop response may be unstable. This paper shows that it is possible to explore the presence of time delays in feedback amplifiers in order ...