Cnsr2011 Fdhymsh Presentation (1)wer gewe gewg secvesvc

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

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Cnsr2011 Fdhymsh Presentation (1)wer gewe gewg secvesvc