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Survey of Free Space Optical (FSO) Communications Opportunities in Next Generation Cellular Networks

Survey of Free Space Optical (FSO) Communications Opportunities in Next Generation Cellular Networks. Frédéric Demers, Halim Yanikomeroglu & Marc St-Hilaire Presented at the Communication Networks and Services Research Conference 4 May 2011. Outline.

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Survey of Free Space Optical (FSO) Communications Opportunities in Next Generation Cellular Networks

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  1. Survey of Free Space Optical (FSO) Communications Opportunities in Next Generation Cellular Networks Frédéric Demers, Halim Yanikomeroglu & Marc St-Hilaire Presented at the Communication Networks and Services Research Conference 4 May 2011

  2. 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

  3. 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 to intercept Effective range limited by weather and eye-safety considerations

  4. Channel model Factors affecting light propagation through the atmosphere Physical composition of atmosphere Changes in refractive indices Aerosol particles

  5. Channel model 850 nm 1550 nm

  6. Channel model Weather • Channel effects: • Absorption • Diffraction • Rayleigh scattering (atmospheric gases molecules) • Mie scattering (aerosol particles) • Atmospheric (refractive) turbulence: • Scintillation • Beam wander

  7. Channel model

  8. 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

  9. Path loss, FSO Intensity of light at point x and time t’ Beer-Lambert Law Space time distribution of species Intensity of transmitter Mie Scattering Absorption Raleigh Scattering M. Bass, "Atmospheric optics," in Handbook of Optics ,Third Edition ed., vol. 5, M. Bass, Ed. McGraw-Hill, pp. 3.3., 2010.

  10. Path loss, FSO Pressure Temperature Humidity Stochastic component Point in space Refractive index of air

  11. 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

  12. Full Optical FSO 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," Communications Magazine, IEEE, vol. 48, pp. 130-137, 2010. No requirement for electrical-optical conversion Easy extension of RF-over-fibre links Wavelength division multiplexing

  13. Hybrid RF/FSO • 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 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.

  14. Mobile FSO Systems • Tightly packed LED transceivers around spherical device • Able to maintain optical link in motion • Experiment rather simplistic 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.

  15. Indoor Diffuse Optical Wireless • Non Line-of-Sight optical communications • Multipath interference an issue, limiting throughput • Hybrid narrow-beam designs provide both bandwidth and coverage 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

  16. 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

  17. Next Generation Cellular Networks Evolved UMTS Terrestrial Access Network (E-UTRAN) Evolved Packet Core MME PDN GW SAE GW p-eNB p-eNB aGW relay relay eNB eNB UE aGW Indoor AP UE

  18. Conclusions Radio frequencies alone will not suffice to provide the required throughput to the end-users Next generation networks will require a denser infrastructure to cater to mobile user needs This denser infrastructure will shorten hops between base stations and ease the establishment of mesh connectivity These architectural changes open the door to an increased reliance upon FSO communication systems PHY layer is not dead! 18

  19. Main references 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, 2005, pp. 164-168. Available: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.143.6352&rep=rep1&type=pdf M. Bass, "Atmospheric optics," in Handbook of Optics ,Third Edition ed., vol. 5, M. Bass, Ed. McGraw-Hill, 2010, pp. 3.3. 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. Available: http://www.ieeexplore.ieee.org.proxy.library.carleton.ca/stamp/stamp.jsp?tp=&arnumber=4446618 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," 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 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. Available: http://www.ece.mcmaster.ca/~hranilovic/woc/resources/local/spie2001b.pdf

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