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Free Space Optics (FSO)

Free Space Optics (FSO). Presented By… Mr. Chandan Kumar dash (05-101) Mr. pankaj jain (05-103). Presentation Overview. Introduction Historical Overview Why free space optics How Fiber Optic Cable Works How FSO work Free Space Optics System Basics

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Free Space Optics (FSO)

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  1. Free Space Optics (FSO) Presented By… Mr. Chandan Kumar dash (05-101) Mr. pankaj jain (05-103)

  2. Presentation Overview • Introduction • Historical Overview • Why free space optics • How Fiber Optic Cable Works • How FSO work • Free Space Optics System Basics • Advantages • Applications • Challenges • The Future of Free Space Optics • Conclusions

  3. Introduction 1. FSO: Free Space Optics. 2. Idea: Transmitting data (voice, video, etc.) using narrow beam light through the space in the Line of Sight (LoS) direction between transmitter and receiver. 3. Almost similar to transmitting signal using fiber optics, but here the space (air) is used as transmission medium instead of fiber. 4. Easy to install connections for the last-mile and campus environments. 5. It provides transmission rates at the speed of light

  4. Historical Overview • Developed in late 60‘s by a German scientist Dr. Erhard Kube “Father of FSO technology” • It has been used by military and NASA for more than 30 years • Now It is seen as an alternative to the widely known fiber optics • Enable the Wall Street Stock Exchange back to business after the 9/11 tragedy in less than 48 hours

  5. Why Free Space Optics?How Fiber Optic Cable Works Glass Fiber Strands Light Source Detector Detector Light Source NetworkDevice NetworkDevice • Pulses of light communicate the data • “ON” = 1 • “OFF = 0

  6. A receiver at the other end of the link collects the light using lenses and/or mirrors 3 Transmitter projects the carefully aimed light pulses into the air 2 Received signal converted back into fiber or copper and connected to the network 4 Network traffic converted into pulses of invisible light representing 1’s and 0’s 1 • Reverse direction data transported the same way. • Full duplex 5 Why Free Space Optics?How FSO Works Anything that can be done in fiber can be done with FSO

  7. Why Free Space Optics?Very Narrow and Directional Beams • Allows VERY close spacing of links without interference • No side lobes • Highly secure • Efficient use of energy • Ranges of 20m to more than 8km possible

  8. Small angle approximation: Angle (in milliradians) * Range (km)= Spot Size (m) 1 m 1 mrad 1 km Why Free Space Optics?Small Angles - Divergence & Spot Size 1°≈ 17 mrad → 1 mrad ≈ 0.0573°

  9. FSO System BasicsMajor Subsystems

  10. Transmit power Transmit Beam Divergence Receiver Aperture Area Receiver Sensitivity Losses: Optical Loss, Geometric Loss Atmospheric Attenuation FSO System BasicsSystem Parameters Important system parameters for reliable and efficient design are

  11. FSO System BasicsGeometric Loss & Transmit Beam Divergence Smaller beam divergence gives smaller geometric loss FSO

  12. AdvantagesComparison With Fiber Optics

  13. AdvantagesLast mile connectivity Head office/server Branch office / LAN

  14. AdvantagesDifferent factor 1. High rates 2. No frequency license required 3. Fast and easy installation 4. Distance up to kms 5. Compatible with other access technology 6. Cost effective, movable asset 7. Near zero latency over all distances 8. Transparent to networks or protocols 9. Internal and external mounting

  15. Applications • Metro network extensions • Last-mile access • Enterprise connectivity • Fiber backup • Backhaul • Service acceleration

  16. ChallengesEnvironmental factors Sunlight Window Attenuation Fog Building Motion Alignment Scintillation Range Obstructions Low Clouds Each of these factors can “attenuate” (reduce) the signal. However, there are ways to mitigate each environmental factor.

  17. ChallengesAttenuation is mainly caused by fog • Absorption or scattering of optical signals due to airborne particles • Primarily FOG but can be rain, snow, smoke, dust, etc. • Can result in a complete outage • FSO wavelengths and fog droplets are close to equal in size Very Dense Fog Loss of 173 dB/km No Fog Loss of 6.5 dB/km Dense Fog Loss of 113 dB/km

  18. ChallengesLow Clouds, Rain, Snow and Dust • Low Clouds • Very similar to fog • May accompany rain and snow • Rain • Drop sizes larger than fog and wavelength of light • Extremely heavy rain (can’t see through it) can take a link down • Water sheeting on windows • Heavy Snow • May cause ice build-up on windows • Whiteout conditions • Sand Storms • Likely only in desert areas; rare in the urban core

  19. ChallengesScintillation • Beam spreading and wandering due to propagation through air pockets of varying temperature, density, and index of refraction. • Almost mutually exclusive with fog attenuation. • Results in increased error rate but not complete outage.

  20. ChallengesBuilding Motion – Thermal Expansion • Results from Seattle Deployment: • 15% of buildings move more than 4 mrad • 5% of buildings move more than 6 mrad • 1% of buildings move more than 10 mrad

  21. Future of FSOShort distance LAN extensions

  22. Future of FSOCellular backhaul network

  23. Conclusions • Free-space optics technology is a good alternative, especially compare to fiber optics • 2. In the future, FSO may be one of the most important access technologies due to its advantages • 3. Big market in the future. • 4. Note: Availability and quality really depends on the environment conditions. • 5. It can solve last mile connectivity

  24. End of Presentation Thank You for Your Attention ……………………

  25. Questions ?

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