Free-Space Optics: A Shifting Paradigm in Optical Communication Systems in Difficult Terrains

Free-space optical (FSO) communication is a high-speed technology that can be used to promote rapid deployment of ubiquitous wireless service at the geographical locations such as hilly areas, where radio frequency (RF) technology is inaccessible and laying of optical fibers is not physically and economically viable. FSO has gained significant importance due to several advantages such as extremely high bandwidth, unlicensed spectrum allocation, reduced power consumption about half of the RF, ease of deployment, improved channel security, and reduced size which is one-tenth of the diameter of RF antenna. However, along with many advantages of FSO, atmosphere poses a serious limitation on its performance causing absorption, scattering, scintillations, and atmospheric turbulences. This paper presents a comprehensive review of FSO technology. FSO basics along with its advantages over RF are described so that readers can easily get the concept of shifting from RF to optical communication. Further, the paper also highlights the challenges faced by FSO, various models to characterize atmospheric turbulence fluctuations, issues, and methods to overcome them.

[1]  George K. Karagiannidis,et al.  BER Performance of FSO Links over Strong Atmospheric Turbulence Channels with Pointing Errors , 2008, IEEE Communications Letters.

[2]  Hazem H. Refai,et al.  Wavelength diversity in free-space optics to alleviate fog effects , 2005, SPIE LASE.

[3]  Payal,et al.  Performance Analysis of NRZ and RZ Modulation Schemes in Optical Fiber Link Using EDFA , 2017 .

[4]  P.R. Herman,et al.  Chirped Bragg Grating Waveguides Directly Written Inside Fused Silica Glass With an Externally Modulated Ultrashort Fiber Laser , 2009, IEEE Photonics Technology Letters.

[5]  L. Andrews.  Field guide to atmospheric optics , 2004 .

[6]  Redhwan Q. Shaddad,et al.  Enhancement of free space optical link in heavy rain attenuation using multiple beam concept , 2013 .

[7]  Heinz Willebrand,et al.  Free Space Optics: Enabling Optical Connectivity in Today's Networks , 2001 .

[8]  Payal,et al.  Nonlinear Impairments in Fiber Optic Communication Systems: Analytical Review , 2018 .

[9]  Maha Achour,et al.  Free-space optics wavelength selection: 10 μm versus shorter wavelengths , 2004, SPIE Optics + Photonics.

[10]  Vaclav Kvicera,et al.  Fog attenuation dependence on atmospheric visibility at two wavelengths for FSO link planning , 2010, 2010 Loughborough Antennas & Propagation Conference.

[11]  Vladimir Vasinek,et al.  Features and range of the FSO by use of the OFDM and QAM modulation in different atmospheric conditions , 2014, Sensing Technologies + Applications.

[12]  Isaac I. Kim,et al.  Comparison of laser beam propagation at 785 nm and 1550 nm in fog and haze for optical wireless communications , 2001, SPIE Optics East.

[13]  Don M. Boroson,et al.  RF and Optical Communications: A Comparison of High Data Rate Returns From Deep Space in the 2020 Timeframe , 2007 .

[14]  Hervé Sizun,et al.  Fog attenuation prediction for optical and infrared waves , 2004 .

[15]  M. Achour.  Free-space optics wavelength selection: 10 µm versus shorter wavelengths[Invited] , 2003 .

[16]  D. Borah,et al.  Pointing Error Effects on Free-Space Optical Communication Links in the Presence of Atmospheric Turbulence , 2009, Journal of Lightwave Technology.

[17]  Syed Alwee Aljunid,et al.  Optimization of free space optics parameters: An optimum solution for bad weather conditions , 2013 .

[18]  Zabih Ghassemlooy,et al.  Terrestrial Free-Space Optical Communications , 2010 .

[19]  Nicolas Perlot,et al.  Aperture averaging: theory and measurements , 2004, SPIE LASE.

[20]  L. Andrews,et al.  Laser Beam Scintillation with Applications , 2001 .

[21]  Reza Nasiri Mahalati,et al.  Effect of fog on free-space optical links employing imaging receivers. , 2012, Optics express.

[22]  Christopher C. Davis,et al.  Aperture averaging of optical scintillations in the atmosphere: experimental results , 2005, SPIE Defense + Commercial Sensing.

[23]  Zabih Ghassemlooy,et al.  Scintillation effect on intensity modulated laser communication systems—a laboratory demonstration , 2010 .

[24]  Robert K. Crane,et al.  ACTS propagation experiment: attenuation distribution observations and prediction model comparisons , 1997, Proc. IEEE.

[25]  G. Kandus,et al.  On the study of the FSO link performance under controlled turbulence and fog atmospheric conditions , 2011, Proceedings of the 11th International Conference on Telecommunications.

[26]  Iosr journals,et al.  Performance Analysis of Fog Effect on Free Space Optical Communication System , 2015 .

[27]  V.W.S. Chan,et al.  Free-Space Optical Communications , 2006, Journal of Lightwave Technology.

[28]  Songnian Fu,et al.  Performance comparison of different modulation formats over free-space optical (FSO) turbulence links with space diversity reception technique , 2009, IEEE Photonics Journal.

[29]  Suresh Kumar,et al.  Performance Evaluation of Proposed WDM Optical Link Using EDFA and FBG Combination , 2018 .

[30]  A. W. Naji,et al.  Proposed parameters of specific rain attenuation prediction for Free Space Optics link operating in tropical region , 2013 .

[31]  Mehdi Rouissat,et al.  Free Space Optical Channel Characterization and Modeling with Focus on Algeria Weather Conditions , 2012 .

[32]  Zabih Ghassemlooy,et al.  BPSK Subcarrier Intensity Modulated Free-Space Optical Communications in Atmospheric Turbulence , 2009, Journal of Lightwave Technology.

[33]  Zabih Ghassemlooy,et al.  Comparison of 830 nm and 1550 nm based free space optical communications link under controlled fog conditions , 2012, 2012 8th International Symposium on Communication Systems, Networks & Digital Signal Processing (CSNDSP).

[34]  Payal Arora,et al.  A Comprehensive Review on Fiber Bragg Grating and Photodetector in Optical Communication Networks , 2019, Journal of Optical Communications.

[35]  Otakar Wilfert,et al.  An Introduction to Free-space Optical Communications , 2010 .

[36]  Eric J. Korevaar,et al.  Understanding the performance of free-space optics [Invited] , 2003 .

[37]  M.N. Junita,et al.  Study of rain attenuation consequence in free space optic transmission , 2008, 2008 6th National Conference on Telecommunication Technologies and 2008 2nd Malaysia Conference on Photonics.

[38]  D. Varoutas,et al.  Weather effects on FSO network connectivity , 2012, IEEE/OSA Journal of Optical Communications and Networking.

[39]  Erich Leitgeb,et al.  Characterization of Fog and Snow Attenuations for Free-Space Optical Propagation , 2009, J. Commun..

[40]  Anshuman Panda,et al.  Free Space Optical Communication: A Review , 2016 .

[41]  Joseph M. Kahn,et al.  Maximum-likelihood spatial-diversity reception on correlated turbulent free-space optical channels , 2000, Globecom '00 - IEEE. Global Telecommunications Conference. Conference Record (Cat. No.00CH37137).