Search results for "COD"

showing 10 items of 2985 documents

Criteri innovativi per la progettazione e produzione eco-compatibile (eco-design) di prodotti che consumano energia (EuP) nel settore civile d'utenza

2013

Settore ING-IND/11 - Fisica Tecnica AmbientaleEcodesign Prodotti che consumano energia EuP
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Correlated Channel Model for terrestrial Free Space Optics and project specifications evaluation of LT code in OOK modulation

2011

Free Space Optics is a wireless line-of-sight communication system able to offer good bandwidth performance as well as straightforward installation and relocation. So that it represents a modern technology that allow to realize large bandwidth communication particularly when it is not possible to employ physical cable or radio technologies. Examples of FSO applications are: wireless backaul, fiber backup, temporary links, metro network extension and last mile access[1]. FSO is based on optical signals propagation in air and that is why it suffers of impairments which depend on atmospheric conditions. In detail, FSO suffers of scattering (i. e. Rayleigh and Mie) losses, absorption and scinti…

Settore ING-INF/02 - Campi ElettromagneticiFree Space Optics FSO OOK LT code Luby Tranform Channel model correlation outage Gamma Gamma Rytov parameterSettore ING-INF/01 - Elettronica
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Rateless Codes Performance Analysis in Correlated Channel Model for GEO Free Space Optics Downlinks

2012

Settore ING-INF/03 - TelecomunicazioniFree Space Optics (FSO) technologies for satellite communications offer several advantages: wide bandwidth high rate capability immunity to electromagnetic interference and small equipment size. Thus they are suitable for inter-satellite links deep space communications and also for high data rate ground-to-satellite/satellite-to-ground communications. Nevertheless FSO links suffer impairments that cause power signal degradation at the receiver. Scattering and absorption cause power signal attenuations predictable by suitable deterministic models. Optical turbulence causes random irradiance fluctuations which can generate signal fading events and can thereby only be predicted by statistical models. Attenuation and fading events can corrupt FSO links and so it would be recommended to add mitigation error codes on the communication link. FSO channel can be described as an erasure channel: fading events can cause erasure errors. We have identified in rateless codes (RCs) a suitable solution to be employed in FSO links. RCs do not need feedback and they add a redundant coding on the source data that allows the receiver to recover the whole payload despite erasure errors. We implemented two different of rateless codes: Luby Transform (LT) and Raptor. We analyzed their performances on a simulated turbulent GEO FSO downlink (1 Gbps - OOK modulation) at a 106 μm wavelength and for different values of zenith angles. Assuming a plane-wave propagation and employing Hufnagel-Valley we modeled the downlink using: 1) a temporal correlated channel model based on Gamma-Gamma probability distribution and 2) an irradiance covariance function that we converted on a time function using Taylor frozen eddies hypothesis. Our new channel model is able to simulate irradiance fluctuations at different turbulence conditions as it will be shown in the full paper. We will also report performance results of LT and Raptor codes at overhead range varying between 0 and 50% and for different values of source packets.Settore ING-INF/01 - Elettronica
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Correlated channel model for terrestrial Free Space Optics: performance analysis of rateless codes

2012

We describe a novel correlated channel model able to predict random temporal fluctuations of optical signal irradiance caused by scintillation. With regards to the same channel, we also report simulation results on the error mitigation performance of Luby-Transform and Raptor codes.

Settore ING-INF/03 - TelecomunicazioniFree Space Optics channel modeling Raptor codes RaptorQ codes LT codes rateless codesSettore ING-INF/02 - Campi ElettromagneticiSettore ING-INF/01 - Elettronica
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Luby Transform Performance Tests on Time-Correlated Channel Model for Geo Free Space Optics Downlinks

2012

Settore ING-INF/03 - TelecomunicazioniSettore ING-INF/01 - ElettronicaFree Space Optics Luby Transform Codes Rateless Codes Channel Modeling Geo Free Space Optics Downlinks
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Performance Investigation of Fountaine Codes on a Simulated Terrestrial Free Space Optical Channel

2012

Settore ING-INF/03 - TelecomunicazioniSettore ING-INF/02 - Campi ElettromagneticiSettore ING-INF/01 - ElettronicaFree Space Optics Channel Modeling Fountain Codes Raptor Codes RaptorQ Codes Luby Transform Codes Rateless Codes
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Optical wireless GEO satellite-to-ground downlinks: rateless codes as solution for scintillation fading

2013

Scintillation fading can corrupt a satellite-to-ground optical wireless links with burst errors. Rateless codes, suitable for erasure channel, are able to eliminate or to reduce these communication errors. We analyzed the performances of three different rateless codes in a simulated Geo satellite-to-ground downlink.

Settore ING-INF/03 - TelecomunicazioniSettore ING-INF/02 - Campi ElettromagneticiSettore ING-INF/01 - ElettronicaFree Space Optics Rateless codes LT codes Raptor codes RaptorQ codes channel modeling
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Fading mitigation coding techniques for space to ground free space optical communications

2014

Settore ING-INF/03 - TelecomunicazioniSpace-to-Ground FSO links time-series rateless codefading mitigationSettore ING-INF/02 - Campi ElettromagneticiOptical Wireless CommunicationSettore ING-INF/01 - Elettronica
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A Reconfigurable Neural Environment on Active Networks

2000

This paper proposes the deployment of a neural network computing environment on Active Networks. Active Networks are packet-switched computer networks in which packets can contain code fragments that are executed on the intermediate nodes. This feature allows the injection of small pieces of codes to deal with computer network problems directly into the network core, and the adoption of new computing techniques to solve networking problems. The goal of our project is the adoption of a distributed neural network for approaching tasks which are specific of the computer network environment. Dynamically reconfigurable neural networks are spread on an experimental wide area backbone of active no…

Settore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniArtificial neural networkNetwork packetbusiness.industryComputer scienceTime delay neural networkDistributed computingActive Networks Neural NetworksComputer network programmingIntelligent computer networkCellular neural networkCode (cryptography)businessComputer networkActive networking
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A Hybrid Framework for Soft Real-Time WSN Simulation

2009

The design of a wireless sensor network is a chal- lenging task due to its intrinsically application-specific nature. Although a typical choice for testing such kind of networks requires devising ad-hoc testbeds, this is often impractical as it depends on expensive, and hard to maintain deployment of nodes. On the other hand, simulation is a valuable option, as long as the actual functioning conditions are reliably modeled, and carefully replicated. The present work describes a framework for supporting the user in early design and testing of a wireless sensor network with an augmented version of TOSSIM, the de-facto standard for simulators, that allows merging actual and virtual nodes seaml…

Settore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniComputer scienceDistributed computingLoad modelingReal-time computingData modelingTask (computing)Key distribution in wireless sensor networksTelecommunication computingSoftware deploymentCode (cryptography)Soft-real timeWireless sensor networkWireless Sensor NetworkSimulation
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