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7/29/2019 Cnsr2011 Fdhymsh Presentation (1)wer gewe gewg secvesvc
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Survey of Free Space
Optical (FSO)Communications
Opportunities in Next
Generation Cellular
Networks
Frdric Demers, Halim Yanikomeroglu &
Marc St-Hilaire
Presented at the
Communication Networks and Services Research
Conference4 May 2011
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Outline
Motivation & Key Characteristics of FSO systems
Channel model and path loss overview
Recent advances in FSO communications Full Optical FSO systems
Hybrid RF/FSO systems
Mobile FSO systems
Indoor diffuse FSO systems
Applications within Next Generation Cellular Networks
Conclusions
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Motivation & key characteristics
RF spectrum scarcity vs increasing throughput
requirements
A single FSO channel can offers Tb/s throughput
wirelessly Free space optical spectrum is license free and
nearly unlimited (very dense reuse)
FSO systems are generally very difficult tointercept
Effective range limited by weather and eye-
safety considerations
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Channel model
Factors affecting light propagation throughthe atmosphere
Physical composition of atmosphere
Changes in refractive indices
Aerosol particles
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5850 nm 1550 nm
Channel model
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Channel model
Channel effects:
Absorption
Diffraction
Rayleigh scattering (atmospheric
gases molecules)
Mie scattering (aerosol particles)
Atmospheric (refractive) turbulence: Scintillation
Beam wander
Weather
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Channel model
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Path loss, RF
Typical RF attenuation (e.g. 2 GHz, 15 dBi antenna gains)
Avg path loss in free space -> 68 dB @ 1km , 118 dB @ 10 km
Avg path loss in mobile radio (n=3.4, d0=100 m) -> 82 dB/km, 146
dB @ 10 km
2
0mobile-radio
0
4n
d dPL d
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Path loss, FSO
0,
, , , ,0
x
N x t dx
I t x I t e
Beer-Lambert Law
AbsorptionRaleigh Scattering
Mie Scattering
Intensity of transmitter
Intensity of light at pointxand time t
Space time distribution of species
a R M
M. Bass, "Atmospheric optics," in Handbook of Optics ,Third
Edition ed., vol. 5, M. Bass, Ed. McGraw-Hill, pp. 3.3., 2010.
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Path loss, FSO
36
0 2
7.53 101 77 1 7733 10
p qn
T T
0Tn n n r r
Refractive index of air
Temperature Humidity
Pressure
Point in space Stochastic component
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Path loss, RF vs FSO
Typical RF attenuation (e.g. 2 GHz, 15 dBi antenna gains)
Avg path loss in free space -> 68 dB @ 1km , 118 dB @ 10 km
Avg path loss in mobile radio (n=3.4, d0=100 m) -> 82 dB/km, 146
dB @ 10 km
Typical optical attenuation (e.g. 1550 nm or 194 THz)
clear atmospheric conditions -> 0.2 dB/km
urban (because of dust) -> 10 dB/km
Rain -> 2-35 dB/km
Snow -> 10-100 dB/km
light fog -> 120 dB/km
dense fog -> 300 dB/km
maritime fog -> 480 dB/km
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Full Optical FSO
No requirement for
electrical-optical
conversion
Easy extension of
RF-over-fibre links
Wavelength division
multiplexing
K. Kazaura, K. Wakamori, M. Matsumoto, T. Higashino, K. Tsukamoto
and S. Komaki, "RoFSO: A universal platform for convergence of fiber
and free-space optical communication networks," CommunicationsMagazine, IEEE, vol. 48, pp. 130-137, 2010.
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Hybrid RF/FSO
I. I. Kim and E. Korevaar, "Availability of free space optics (FSO) and
hybrid FSO/RF systems," Optical Wireless Communications IV, EJ
Korevaar, Eds. , Proc. SPIE, vol. 4530, pp. 84-95, 2001.
FSO is most affected by fog, RF by
rain
RF links complements FSO to
achieve carrier class availability
(99.999%)
Lower throughput in adverse
weather
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J. Akella, C. Liu, D. Partyka, M. Yuksel, S. Kalyanaraman and P. Dutta,
"Building blocks for mobile free-space-optical networks," in Wireless
and Optical Communications Networks, 2005. WOCN 2005. Second
IFIP International Conference on, pp. 164-168, 2005.
Mobile FSO Systems
Tightly packed LED
transceivers around
spherical device
Able to maintain optical
link in motion
Experiment rather
simplistic
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Indoor Diffuse Optical Wireless
R. J. Green, H. Joshi, M. D. Higgins and M. S. Leeson,
"Recent developments in indoor optical wireless systems,"
IET Communications, vol. 2, pp. 3, 2008
Non Line-of-Sight optical
communications
Multipath interference an
issue, limiting throughput
Hybrid narrow-beam
designs provide both
bandwidth and coverage
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Next Generation Cellular Networks
Densification of access points (eNodeB)
Shorter hops
Suitability to mesh connectivity
Heterogeneous access points
Relaying
Distributed antennas
Coordinated Multi-Point Transmission &Reception (CoMP)
Self-Organizing Networks
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p-eNB
relay
eNB
p-eNB
eNB
relay
Next Generation Cellular Networks
MME SAE
GW
aGW
aGW
PDN
GW
Evolved Packet CoreEvolved UMTS Terrestrial Access Network (E-UTRAN)
UE
Indoor AP
UE
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Conclusions
Radio frequencies alone will not suffice to providethe required throughput to the end-users
Next generation networks will require a denserinfrastructure to cater to mobile user needs
This denser infrastructure will shorten hopsbetween base stations and ease theestablishment of mesh connectivity
These architectural changes open the door to anincreased reliance upon FSO communication
systemsPHY layer is not dead!
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Main references
1. J. Akella, C. Liu, D. Partyka, M. Yuksel, S. Kalyanaraman and P. Dutta, "Building blocks formobile free-space-optical networks," in Wireless and Optical Communications Networks, 2005.WOCN 2005. Second IFIP International Conference on, 2005, pp. 164-168. Available:http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.143.6352&rep=rep1&type=pdf
2. M. Bass, "Atmospheric optics," in Handbook of Optics ,Third Edition ed., vol. 5, M. Bass, Ed.McGraw-Hill, 2010, pp. 3.3.
3. R. J. Green, H. Joshi, M. D. Higgins and M. S. Leeson, "Recent developments in indoor opticalwireless systems," IET Communications, vol. 2, pp. 3, 2008. Available:http://www.ieeexplore.ieee.org.proxy.library.carleton.ca/stamp/stamp.jsp?tp=&arnumber=4446618
4. K. Kazaura, K. Wakamori, M. Matsumoto, T. Higashino, K. Tsukamoto and S. Komaki,"RoFSO: A universal platform for convergence of fiber and free-space optical communicationnetworks," Communications Magazine, IEEE, vol. 48, pp. 130-137, 2010. Available:
http://www.ieeexplore.ieee.org.proxy.library.carleton.ca/stamp/stamp.jsp?tp=&arnumber=5402676
5. I. I. Kim and E. Korevaar, "Availability of free space optics (FSO) and hybrid FSO/RFsystems," Optical Wireless Communications IV, EJ Korevaar, Eds. , Proc. SPIE, vol. 4530,pp. 84-95, 2001. Available:http://www.ece.mcmaster.ca/~hranilovic/woc/resources/local/spie2001b.pdf