Search results for "Transmitter"
showing 10 items of 348 documents
Energy Efficient Resource Allocation for OFDMA Two-Way Relay Networks with Channel Estimation Error
2015
In this work, we consider the practical issues of resource allocation problem in OFDMA two-way relay networks: the inaccuracy of channel-state information (CSI) available to the transmitters. Instead, only the estimated channel status is known by the transmitters. In this context, a joint optimization of subcarrier pairing and allocation, relay selection and transmit power allocation is formulated in the OFDMA two-way amplify-and-forward relay networks. Moreover, to ensure the Quality of Service (QoS) requirement, the energy consumption must be minimized without compromising the QoS. Therefore, by applying convex optimization techniques, energy efficient algorithms are developed with the ob…
Connection Of System Measuring Voltages And Currents Of High Voltage Power Line To A Microcomputer By Optical Fibre Link
1986
The prototype of equipment for service of the measuring units of power high voltage line is presented. That system is composed of the transmitter /with A/D conversion/, optical fibre data link and receiver feeding the output into the microcomputer. The application of this equipment in the automatic protection system protecting the power network against short-circuit is described.
Packet loss recovery in an indoor Free Space Optics link using rateless codes
2014
Free Space Optics (FSO) systems present some important advantages if compared to Radio Frequency links, but they can be affected by several impairments that degrade the link quality and availability. In particular, due to temporary interruptions of the line-of-sight condition between the transmitter and the receiver, packet loss can occur during data transmission. In this work, we present an indoor Free Space Optics link, in which we have systematically generated interruptions of the beam. We demonstrate how the application of the most recent rateless codes, i.e., RaptorQ codes, can strongly improve the link quality by reducing packet loss. In particular, results show that the Packet Error …
Baseband predistorter using direct spline computation
2005
A baseband predistorter is presented. Key features of the predistorter reside in the use of cubic spline interpolation to generate predistorted input data to the power amplifier, without time convergence problems of classical approaches, with the goal of a reduction in the computational effort. Simulated behaviour of the proposed scheme is presented, demonstrating the effectiveness of the approach.
A Non-Stationary MIMO Vehicle-to-Vehicle Channel Model Derived from the Geometrical Street Model
2011
In this paper, we derive a non-stationary multiple-input multiple-output (MIMO) vehicle-to-vehicle (V2V) channel model from the geometrical street model. Single-bounce scattering is assumed for both fixed and moving scatterers. The high mobility of the transmitter, the receiver, and the surrounding vehicles results in time-variant angles-of-departure (AODs) and angles-of-arrival (AOAs). This fact makes the model non-stationary. Starting from the geometrical model, an analytical expression is derived for the channel gain taking into account the impact of fixed and moving scatterers. The statistical properties of the proposed channel model are studied. Analytical solutions are provided for th…
Improving the efficiency of a standard compliant wireless battery charger
2012
In this paper, a wireless charger for portable electronics devices is presented. A power transmitter, also known as the magnetic pad, and a power receiver are magnetically coupled. A receiver architecture which improves the power conversion efficiency is proposed. All advantages brought by the proposed architecture are discussed and standard constraints are presented as well. The receiver is fully standard-compliant. A wireless station for mobile application is designed and tested. Simulation and experimental results are compared. As shown by experimental results, thanks to the proposed architecture the power conversion efficiency of the receiver section is really close to a unit value. Pow…
UWB Channel Measurements for Hand-Portable Devices: A Comparative Study
2007
On-body UWB signal propagation is analyzed using two different types of UWB antennas. For the study, measurements of the frequency response by means of a VNA (vector network analyzer) are performed at 2001 discrete frequency points in the 3 to 6 GHz range. Separated measures are taken for four different transmitter positions on the head and six receiver positions on the body. Channel estimation parameters, such as mean excess delay, delay spread and path loss are obtained. Results are similar for both types of antennas regarding path loss exponent and average power delay profiles.
UWB Channel Measurements for Measures for Hand-Portable and Wearable Devices
2007
On-body UWB signal propagation is analyzed for propagation channels surrounding the body in an usual office environment for an application requiring the transmission of signals recorded from the head to a device such as a mobile phone or a PDA carried by the subject or also from the transmitter on the head to other devices located along the body. For the study, measurements of the frequency response by means of a VNA (Vector Network Analyzer) are performed at 2001 discrete frequency points in the 3 to 6 GHz range. Channel estimation parameters, such as mean excess delay, delay spread and path loss are obtained. Results show that for the transmitter located on top of the head best average pe…
Drug interactions at GABA(A) receptors.
2002
Neurotransmitter receptor systems have been the focus of intensive pharmacological research for more than 20 years for basic and applied scientific reasons, but only recently has there been a better understanding of their key features. One of these systems includes the type A receptor for the gamma-aminobutyric acid (GABA), which forms an integral anion channel from a pentameric subunit assembly and mediates most of the fast inhibitory neurotransmission in the adult vertebrate central nervous system. Up to now, depending on the definition, 16-19 mammalian subunits have been cloned and localized on different genes. Their assembly into proteins in a poorly defined stoichiometry forms the basi…
Expression of synapsin I gene in primary cultures of differentiating rat cortical neurons
1995
Synapsin I is a neuron-specific protein which is present in two isoforms, Ia and Ib. In the last few years this protein has been demonstrated to play a central role in the regulation of neurotransmitter release and synaptic plasticity. In this paper the developmental expression of this protein has been investigated in primary neuronal cultures from fetal rat brain cortices. The presence of thyroid hormone in the culture medium stimulates an early expression of the protein without exerting any effect at the level of mRNA transcription and accumulation. These observations implicate a T3-dependent regulation of this neuron-specific gene at the level of mRNA translation. © 1995 Plenum Publishin…