Search results for "Free Space Optics"

showing 10 items of 14 documents

Contribution à l'étude des liaisons optiques atmosphériques : propagation, disponibilité et fiabilité.

2005

In this work we study the fog attenuation in the visible and infrared spectral band related to Free Space Optics (FSO). Based on the Mie scattering theory, fog extinction coefficients for different particle size distributions as a function of wavelength were derived. A simple analytical model allowing the prediction of atmospheric transmission for the 0.69 - 1.55 µm spectral band was developed. This model is valid for advection and convection fog and for visibility range between 50 to 1000 m. This model, implemented into software developed at FT R&D, allows the prediction of the Quality of Service of FSO links. Finally, we performed an experimental study to compare the fog effect on two FSO…

Absorption moléculairePropagation optique dans l'atmosphèreAtténuation atmosphérique.[ PHYS.PHYS.PHYS-ATOM-PH ] Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph]Mie scattering theoryvisible and infrared wave propagation in the atmosphereLiaisons optiques atmosphériquesDistribution de taille de particulesfogFree space opticsatmospheric attenuation.AérosolsBrouillardparticle size distribution[PHYS.PHYS.PHYS-ATOM-PH] Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph]Atténuation atmosphériqueThéorie de diffusion de Miemolecular absorption
researchProduct

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)
researchProduct

Analyses of Dual Polarization WDM and SCM Radio over Fiber and Radio over FSO for C-RAN Architecture

2016

En este trabajo se simulan y verifican experimentalmente los esquemas de transmisión para una Arquitectura de Red de Acceso Radio Centralizada (C-RAN) basados en la combinación de dos tecnologías: Radio sobre Fibra (RoF) y Radio sobre FSO (RoFSO). Las configuraciones propuestas se optimizan para la evolución a largo plazo (LTE) con un ancho de banda de 20 MHz utilizando una modulación de amplitud en cuadratura de 64-QAM en términos de magnitud de vector de error (EVM). En primer lugar, se comparan las mediciones de la multiplexación por división de polarización mediante la combinación de RoF y RoFSO (PDM-RoF/FSO) con los modelos de simulación. Esto se amplía con la combinación de PDM-Multip…

EngineeringUNESCO::CIENCIAS TECNOLÓGICAS::Tecnología de las telecomunicaciones ::Radiocomunicacioneswavelength division multiplex02 engineering and technologyPolarization-division multiplexingMultiplexingFrequency-division multiplexing020210 optoelectronics & photonicsRadio over fiberWavelength-division multiplexing0202 electrical engineering electronic engineering information engineeringElectronic engineeringRadio access networkbusiness.industryradio access networksUNESCO::FÍSICA::Óptica ::Fibras ópticas:FÍSICA::Óptica ::Optica física [UNESCO]:FÍSICA::Óptica ::Fibras ópticas [UNESCO]free space optics:CIENCIAS TECNOLÓGICAS::Tecnología de las telecomunicaciones ::Radiocomunicaciones [UNESCO]UNESCO::FÍSICA::Óptica ::Optica físicaradio over fiberbusinessStatistical time division multiplexingoptical fiber networksQuadrature amplitude modulation
researchProduct

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
researchProduct

Model Analysis of Hydrometeor Scattering Effects on Free Space Near-Infrared Links

2012

A promising technology for peer-to-peer connections and urban area networks is represented by wireless communications through free space using optical carrier (Free Space Optics, FSO). This technology ensures high data rates, with relatively low error rates, low power consumption and inherent security. Nevertheless FSO links are quite sensitive to atmospheric condition. Fog droplets, but also raindrops and snowflakes, may introduce severe path attenuation which drastically reduces the channel availability. A parametric model to simulate droplets scattering effects over the FSO link in terms of extinction coefficient, albedo factor and asymmetry coefficient as function of the particle water …

PhysicsScatteringbusiness.industrySettore ING-INF/03 - TelecomunicazioniAttenuationOptical communicationSettore ING-INF/02 - Campi ElettromagneticiMolar absorptivityOpticsfree space optics; water contents; atmospheric data and optical modellingfree space optics atmospheric data and optical modelling water contents.atmospheric data and optical modellingOptical Carrier transmission ratesParametric modelwater contentsfree space opticsSnowflakebusinessFree-space optical communication
researchProduct

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
researchProduct

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
researchProduct

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
researchProduct

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
researchProduct

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
researchProduct