Search results for "rateless code."

showing 10 items of 16 documents

Error mitigation using RaptorQ codes in an experimental indoor free space optical link under the influence of turbulence

2015

In free space optical (FSO) communications, several factors can strongly affect the link quality. Among them, one of the most important impairments that can degrade the FSO link quality and its reliability even under the clear sky conditions consists of optical turbulence. In this work, the authors investigate the generation of both weak and moderate turbulence regimes in an indoor environment to assess the FSO link quality. In particular, they show that, due to the presence of the turbulence, the link experiences both erasure errors and packet losses during transmission, and also compare the experimental statistical distribution of samples with the predicted Gamma Gamma model. Furthermore,…

Computer scienceOptical linkReliability (computer networking)Optical linksTelecommunication network reliabilityRytov variance valueSettore ING-INF/01 - ElettronicaTelecomunicacióRaptorQ codesRedundancy (information theory)Indoor free space optical linkFSO communicationsStatisticsTEORIA DE LA SEÑAL Y COMUNICACIONESRedundancy (engineering)Gamma Gamma modelrateless codeElectrical and Electronic Engineeringpacket error rate (PER)Error-free transmissionNetwork packetbusiness.industrySettore ING-INF/03 - TelecomunicazioniSettore ING-INF/02 - Campi ElettromagneticiÒpticaComputer Science ApplicationsTransmission (telecommunications)Bit error rateErasureProbability distributionFree Space Optical (FSO) communicationTelecommunicationsbusinessOptical turbulenceFSO link reliabilityindoor linkError mitigation
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Recovery Capabilities of Rateless Codes on Simulated Turbulent Terrestrial Free Space Optics Channel Model

2013

Free Space Optics (FSO) links are affected by several impairments: optical turbulence, scattering, absorption, and pointing. In particular, atmospheric optical turbulence generates optical power fluctuations at the receiver that can degrade communications with fading events, especially in high data rate links. Innovative solutions require an improvement of FSO link performances, together with testing models and appropriate channel codes. In this paper, we describe a high-resolution time-correlated channel model able to predict random temporal fluctuations of optical signal irradiance caused by optical turbulence. Concerning the same channel, we also report simulation results on the error mi…

EngineeringArticle SubjectIrradianceOptical powerSettore ING-INF/01 - ElettronicaSignaloptical turbulenceElectronic engineeringFadingElectrical and Electronic Engineeringtime-serieComputer Science::Information TheorySettore ING-INF/03 - TelecomunicazioniTurbulenceScatteringbusiness.industryRateless codesSettore ING-INF/02 - Campi Elettromagneticilcsh:HE9713-9715Free Space Opticlcsh:Cellular telephone services industry. Wireless telephone industrylcsh:Electrical engineering. Electronics. Nuclear engineeringbusinesslcsh:TK1-9971Communication channelFree-space optical communicationInternational Journal of Antennas and Propagation
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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 …

EngineeringSettore ING-INF/03 - TelecomunicazioniNetwork packetbusiness.industryTransmitterFree Space Optics (FSO) packet loss rateless codes RaptorQSettore ING-INF/01 - ElettronicaPacket lossEncoding (memory)Electronic engineeringBit error ratebusinessDecoding methodsFree-space optical communicationData transmission2014 16th International Conference on Transparent Optical Networks (ICTON)
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Rateless codes mitigation technique in a turbulent indoor Free Space Optics link

2014

Free Space Optics (FSO) links are affected by several impairments and, among them, optical turbulence is the most important factor that can degrade the link quality. Due to the presence of this phenomenon, the signal irradiance detected by the receiver fluctuates, thus causing erasure errors and fading events. In this work, we present an indoor Free Space Optics link, in which several turbulence conditions are generated by using two heating elements. We show that the generated turbulence causes erasure errors and packet losses during the data transmission, and we also compare the statistical distribution of the samples with the theoretical models. Moreover, we demonstrate how the applicatio…

PhysicsNetwork packetSettore ING-INF/03 - TelecomunicazioniEncoding (memory)Electronic engineeringBit error rateErasureFadingSettore ING-INF/01 - ElettronicaDecoding methodsFree Space Optics (FSO) optical turbulence rateless codes RaptorQFree-space optical communicationData transmission
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Moderate-to-Strong Turbulence Generation in a Laboratory Indoor Free Space Optics Link and Error Mitigation via RaptorQ Codes

2016

Free Space Optics (FSO) is rapidly gaining interest as a line-of sight communication technology that offers capabilities similar - in terms of bandwidth and transfer rates - to optical fibre, also possessing several advantages compared with traditional radio frequency links. However, FSO link quality can be strongly affected by unfavourable weather conditions and also by the phenomenon of optical turbulence, even in clear sky. In this work, we have implemented an indoor FSO link and generated moderate-to-strong turbulence conditions along the optical path by using heaters and a mechanical ventilation system. In this way, we have been able to investigate the effects of the generated turbulen…

Physicsbusiness.industryNetwork packetFree Space Optics (FSO) indoor link turbulence generation packet loss rateless codes RaptorQ codesSettore ING-INF/03 - Telecomunicazioni05 social sciencesBandwidth (signal processing)050801 communication & media studies020206 networking & telecommunicationsSettore ING-INF/02 - Campi Elettromagnetici02 engineering and technologySettore ING-INF/01 - ElettronicaData recovery0508 media and communicationsOptical path0202 electrical engineering electronic engineering information engineeringBit error rateElectronic engineeringRadio frequencybusinessAdaptive opticsFree-space optical communication
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Rateless Codes Performance Tests On Terrestrial FSO Time-Correlated Channel Model

2012

Free Space Optics (FSO) links are affected by several impairments: optical turbulence, scattering, absorption, and pointing. In particular, atmospheric optical turbulence generates optical power fluctuations at the receiver that can degrade communications with fading events, especially, in high data rate links. A way to mitigate FSO link outages can be to add a coding to communications. Nevertheless, in order to study innovative solutions (software or hardware) and to improve the FSO link performance it needs accurate testing models. In this paper we describe an accurate time-correlated channel model able to predict random temporal fluctuations of optical signal irradiance caused by optical…

Physicsbusiness.industrySettore ING-INF/03 - Telecomunicazionicorrelated channelrateless code.Fountain codeOptical powerSettore ING-INF/02 - Campi ElettromagneticiOptical performance monitoringRaptorQ (RQ)Settore ING-INF/01 - ElettronicaSoftwareFree Space Optics (FSO)Luby Tranform (LT)Electronic engineeringFadingbusinessRaptor codeTransform codingAtmospheric opticsComputer Science::Information TheoryCoding (social sciences)Free-space optical communication
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Rateless codes implementation, optimization and application to Free Space Optics links affected by optical turbulence

In this work, I have implemented, optimized and tested the most advanced rateless codes available up to now, i.e., RaptorQ codes. In detail, a multiplatform data transmission software has been appositely developed in order to verify the effectiveness of the above-mentioned codes to decrease packet loss and hence to improve the link quality, under different network and channel conditions. Several simulative and experimental investigations have been carried out to evaluate the performance of the encoding and decoding schemes and the relative recovery capabilities under different test scenarios. In particular, I have applied the software embedding RaptorQ codes to Free Space Optics communicati…

RaptorQ codesoptical turbulenceFree Space Opticrateless codeGamma-Gamma modelSettore 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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