## Final term paper ppt##

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## Final term paper ppt##

  1. 1. 1
  2. 2. CONTENTSFSO TechnologyWhy FSO?Features and BenefitsSystem OverviewSystem designApplicationChallengesConclusion2
  3. 3. FSO - Technology• Fiber less laser driven LOS technology• No licensing required• FSO links are full duplex• Operating wavelength range• 780-900nm• 1500-1600nm• Use invisible modulated beams of light instead ofradio waves• Transmission speed up to 1.25 Gbps3
  4. 4. WHY FSO?• Electro-magnetic frequencyspectrum has been gobbled up.• The airwaves are becomingseverely overcrowded.• Little space left in the radiospectrum, to add moreinformation channels.• For this reason, manycompanies and individuals arelooking toward light(opticalcommunication). 4
  5. 5. Features and Benefits• Very high data-rates (several Gbps).• Small beam divergence minimizesfree-space losses.• Low power-consumption.• Requires no RF spectrum licensing.• Is easily upgradeable.• Requires no security softwareupgrades.• Long range point to point links.• No cables required. 5
  6. 6. SYSTEM OVERVIEW6
  7. 7. How FSO works?71 Network trafficconverted intopulses ofinvisible light .2Transmitter projects thecarefully aimed light pulsesinto the air5 Reverse direction datatransported the same way.• Full duplex3 A receiver at the other end of thelink collects the light usinglenses and/or mirrors4 Received signalconverted back intofiber or copper andconnected to thenetworkAnything that can be done in fiber canbe done with FSO
  8. 8. How FSO works? Conti…• Optical wireless unit uses an optical sources +transmitting lens or telescope that transits lightthrough the atmosphere to receiving lens.• It transmit invisible, eye-safe light beams fromsource to destination using low power infrared laserin the THz spectrum.• Light focused on highly sensitive detector receiver.• At this point, the receiving lens or telescope connectwith optical cable which gives our originalinformation. 8
  9. 9. Transceiver Unit• The received laser beam (yellow) is much wider than thetransmitted beam (red). That’s why the receiver lens is somuch larger than the transmitter lens.• Both lenses, which share the same axis.9
  10. 10. COMPONENTS OF TRANSRECEIVER• The modulated light source, is a LASER, which providesthe transmitted optical signal.LASER1. Modulates at 20 Mbps to 2.5 Gbps2. Coherent, Operate in the 850 to 1550 wavelength bandPIN photodiodes• Inexpensive• Sensitive in the red and infrared spectrumAvalanche Photodiodes (APD)• Expensive• Excellent red sensitivity 10
  11. 11. Narrow and Directional Beams• Beams only a few meters in diameter at a kilometer• Allows VERY close spacing of links without interference• Highly secure• Efficient use of energy• Ranges of 20m to more than 8km possible11
  12. 12. Requirements of a goodtransmission systemHigh BandwidthLow BERHigh SNRPower efficientProvide DataSecurity.Low costEasy to install andmaintain 12
  13. 13. System design• LOS OPERATION• SPECTRAL ALLOCATION• ALTERNATE ROUTING• NETWORK TOPOLOGIES• NETWORK SCALABILITY• COVERAGE AREA• DEPLOYMENT ANDINSTALLATION13
  14. 14. Application• Deep space communications.• Building to building computer data links; very highdata rates.• Weather, geophysical, remote communication.• Optical radar; shape, speed, direction and range.• Remote telephone links; cheaper than microwave.• Metro network extensions.• Campus wide computer networks.• City-wide information broadcasting .• Inter-office data links. 14
  15. 15. 15SunlightScintillationObstructionWindowAttenuationFogBuildingMotionLow CloudsAlignmentRangeEach of these factors can “attenuate” (reduce) the signal.However, there are ways to mitigate each environmental factorEnvironmental factors
  16. 16. CHALLENGES FOR FSOAtmosphere(Fog)- Design a networkthat shortens FSO link distancesAbsorption - Suspended watermolecules in the atmosphereextinguish photons. Thus decreasepower density (attenuation) of beam .Scattering - Scattering is causedwhen the wavelength collides with thescatterer.• Reyleigh scattering-When the scattereris smaller than the wavelength.• Mie scattering-When the scatterer is ofcomparable size to the wavelength.16fogsmoke
  17. 17. Continued…. Physical obstructions: Flying birdscan temporarily block a beam, but thistends to cause only shortinterruptions.Building sway/seismic activity: Itcan upset receiver and transmitteralignment.Safety: It is also a concern becausethe technology uses lasers fortransmissionScintillation: Heated air rising fromthe earth creates temperaturevariations among different air pocketsand cause fluctuations in signalamplitude 17
  18. 18.  Disaster management as wasexhibited during the Sept 11attacks. Merill Lynch & Co. has set upFSO system from its VeseyStreet office towers across theHudson River to an alternatesite in New Jersey. TeraBeam, a major producer ofFSO equipment, successfullydeployed FSO at the SydneySummer Olympic Games. A network of FSO devices is fastcoming up in Seattle which istouted as the Capital of Fog. 18Implementation of FSO
  19. 19. Conclusion• It give very high data rate.• Very cheaper than fiber opticcommunication.• Can be deployed behindwindows, if rooftop sites arecostly.• Also used for temporaryconnection.• Give more informationsecurity than other technology,requires no security software. 19
  20. 20. THANK YOU!!!20
  21. 21. Q & AThank you for giving your attention!40

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