1 FREE-SPACE OPTICAL FREE-SPACE OPTICAL COMMUNICATION USING SUBCARRIER COMMUNICATION USING SUBCARRIER INTENSITY MODULATION INTENSITY MODULATION POPOOLA, Wasiu O. (2 nd Year PhD student) Optical Communication Research Lab., CEIS [email: [email protected]] Supervision Team: Supervision Team: Fary Ghassemlooy – Director of studies Joseph Allen Erich Leitgeb ( University of Technology, Graz, Austria.) Steven Gao (now at University of Surrey)
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FREE-SPACE OPTICAL COMMUNICATION USING SUBCARRIER INTENSITY MODULATION
FREE-SPACE OPTICAL COMMUNICATION USING SUBCARRIER INTENSITY MODULATION. POPOOLA, Wasiu O. (2 nd Year PhD student) Optical Communication Research Lab., CEIS [email: [email protected] ]. Supervision Team: Fary Ghassemlooy – Director of studies Joseph Allen - PowerPoint PPT Presentation
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FREE-SPACE OPTICAL COMMUNICATION FREE-SPACE OPTICAL COMMUNICATION USING SUBCARRIER INTENSITY USING SUBCARRIER INTENSITY
MODULATIONMODULATION
POPOOLA, Wasiu O.(2nd Year PhD student)
Optical Communication Research Lab., CEIS[email: [email protected] ]
Supervision Team:Supervision Team:Fary Ghassemlooy – Director of studiesJoseph AllenErich Leitgeb ( University of Technology, Graz, Austria.)Steven Gao (now at University of Surrey)
xDSL: Copper based (limited bandwidth)- Phone and data combined Availability, quality and data rate depend on proximity to service provider’s C.O.
Radio link: Spectrum congestion (license needed to reduce interference) Security worries (Encryption?) Lower bandwidth than optical bandwidth At higher frequency where very high data rate are possible, atmospheric attenuation(rain)/absorption(Oxygen gas) limits link to ~1km
Cable: Shared network resulting in quality and security issues. Low data rate during peak times
FTTx: Expensive Right of way required - time consuming Might contain copper still etc
1880 - Alexander Graham Bell demonstrated the photophone – 1st FSO (THE GENESIS)
(www.scienceclarified.com)
1960s - Invention of laser and optical fibre1970s - FSO mainly used in secure military applications1990s to date - Increased research & commercial use due to successful trials
In addition to bringing huge bandwidth to businesses /homes FSO also finds applications in :
Multi-campus universityHospitals
Others: Inter-satellite communication Disaster recovery Fibre communication back-up Video conferencing Links in difficult terrains Temporary links e.g. conferencesCellular communication back-haul
I : Received irradianceIx: due to large scale effects; obeys Gamma distributionIy: due to small scale effects; obeys Gamma distributionKn(.): modified Bessel function of the 2nd kind of order n σl
Performs optimally without adaptive threshold as is the case with optimal OOK
Efficient coherent modulation techniques such as PSK, QAM can be easily used because the bulk of the signal processing is done in RF where matured devices like stable, low phase noise oscillators and selective filters are readily available.
System capacity/throughput can be increased
It outperforms OOK in atmospheric turbulence .
Eliminates the use of equalisers in dispersive channels.
Similar schemes already in use on existing networks
The average transmit power increases as the number of subcarrier increases or suffers from signal clipping. Intermodulation distortion due to multiple subcarrier impairs its performance
1. W.O. Popoola, Z. Ghassemlooy,: “MIMO Free-Space Optical Communication Employing Subcarrier Modulation in Clear Atmospheric Turbulence” IEEE Transaction on communications (Under review)
2. W. O. Popoola, Z Ghassemlooy, J I H Allen, E Leitgeb, S Gao: “ Free-Space Optical Communication employing Subcarrier Modulation and Spatial Diversity in Atmospheric Turbulence Channel” IET Optoelectronics, (In print).
3. Ghassemlooy, Z., Popoola, W. O., and Aldibbiat, N. M.: “Equalised Dual Header Pulse Interval modulation for diffuse optical wireless communication system”, Mediterranean J. of Electronics and Communications, Vol. 2, No. 1, 2006.pp. 56-61.
Conference Papers
1. W.O.Popoola and Z. Ghassemlooy,: “Performance of Subcarrier Modulated Free-Space Optical Communication Link in Negative Exponential Atmospheric Turbulence Environment”, IEEE-ICC 2008 (Under review)
2. W.O. Popoola and Z. Ghassemlooy.: “Free-Space optical communication in atmospheric turbulence using DPSK subcarrier modulation”, Ninth International Symposium on Communication Theory and Applications, ISCTA'07, 16th - 20th July, 2007, Ambleside, Lake District, UK, pp.
3. Z. Ghassemlooy, W.O. Popoola, and E. Leitgeb. “Free-Space optical communication using subcarrier modulation in Gamma-Gamma atmospheric turbulence” Invited paper. 9th International Conference on Transparent Optical Networks, July 1-5, 2007 - Rome, Italy, pp.
4. W. O. Popoola, Z. Ghassemlooy and J. I. H. Allen. “Performance of subcarrier modulated Free-Space optical communications”, 8th Annual Post Graduate Symposium on the Convergence of Telecommunications, Networking and Broadcasting (PGNET), 28th & 29th June 2007, Liverpool, UK.
5. S. Rajbhandari, Z. Ghassemlooy, N. M. Aldibbiat, M. Amiri, and W. O. Popoola.: “Convolutional coded DPIM for indoor non-diffuse optical wireless link”, 7th IASTED International Conferences on Wireless and Optical Communications (WOC 2007), Montreal, Canada, May-Jun. 2007, pp. 286-290.
6. Popoola, W. O., Ghassemlooy, Z., and Amiri, M.: "Coded-DPIM for non-diffuse indoor optical wireless communications", PG Net 2006, ISBN: 1-9025-6013-9, Liverpool, UK, 26-27 June 2006. pp. 209-212.
7. Popoola, W. O., Ghassemlooy, Z., and Aldibbiat, N. M.: "DH-PIM employing LMSE equalisation for indoor infrared diffuse systems", 14th ICEE 2006, Tehran, Iran.
8. W. O. Popoola, Z. Ghassemlooy and N. M. Aldibbiat: "Performance of DH-PIM employing equalisation for diffused infrared communications", LCS 2005, London, Sept. 2005, pp. 207-210.
Posters
1. Popoola, W. O., and Ghassemlooy, Z.: “Free space optical communication”, UK GRAD Programme Yorkshire & North East Hub, Poster Competition & Network Event, Leeds, 9 May 2007, Poster No. 52.
Phoenix – atmospherically excellent Denver – atmospherically good Seattle – atmospherically fair London – atmospherically poor
10,000+24001200630
99.9
Phoenix – atmospherically excellent Denver – atmospherically good Seattle – atmospherically fair London – atmospherically poor
5200850420335
99.99
Phoenix – atmospherically excellent Denver – atmospherically good Seattle – atmospherically fair London – atmospherically poor
460290255185
Availability ranges are based upon two 125/155 Mbit/s FSO transceivers that are located outdoors and transmitting through clear air under normal operating conditions. (Bloom, S. et al. 2003)