PRESENTED BY-

CHANDANI

AMANDEEP KAUR

RAJAN KUMAR MISHRA

FREE SPACE OPTICS

COMMUNICATION

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LAYOUTS

HISTORY OF FSO INTRODUCTION ARCHITECTURE WORKING OF FSO LINK & SYSTEM DESIGN LAST MILE BOTTLENECK SECURITY ISSUE CHALLENGES ADVANTAGE & DISADVANTAGE APPLICATION MANUFACTURES CONCLUSION REFERENCES

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HISTORY OF FSO

Greek’s used fire for messaging.

On Feb 19,1880 Alexander Graham Bell and his assistant Charles Sumner Tainter created “Photo Phone(Radio Phone)” was practically first used in military comm. system.

In 2008 the company MRV Comm. has introduced the free space optic based Terescope TS-10GE system with data rate 10Gbps on a distance till 350m.

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Requirements of a good Transmission System: High Bandwidth High Bit Rate Low SNR Power efficient Provide Data Security. Low cost Easy to install and maintain.

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INTRODUCTION Free Space Optics communications, also

called Free Space Photonics (FSP) or Optical Wireless, refers to the transmission of visible and infrared (IR) beams through the atmosphere to obtain optical communications.

FSO is a line-of-sight technology which uses LASERS and Photo detectors to provide optical connections between two points—without the fiber.

Free space optical communication is an effective means of communication at high bit rates over short distances.

Free Space Optics uses lasers and LED to transmit data, but instead of enclosing the data stream in a glass fiber, it is transmitted through the air.

It is a device that allows for the transmission of sound on a beam of light

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FSO Major Sub System

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ARCHITECTURE

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WORKING

The electrical signal is converted to optical power and

transmitted through the air.

After undergoing the influences of the time-dispersive

channel and ambient light, the optical signal is directly

translated into a photocurrent at the detector.

The electrical SNR in optical links depends on the

square of the optical power, which has a deep impact on

both design and performance of OW systems.

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Why Free Space Optics?

How FSO Works

1 Network traffic converted into pulses of invisible light representing 1’s and 0’s

2 Transmitter projects the carefully aimed light pulses into the air

5 Reverse direction data transported the same way.

• Full duplex

3 A receiver at the other end of the link collects the light using lenses and/or mirrors

4Received signal converted back into fiber or copper and connected to the networkAnything that can be done in

fiber can be done with FSO

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SYSTEM DESIGN

Line of sight operation

Spectral AllocationFSO link operationCoverage area Installation Network

topologies

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AT TRANSMITTER:

One or more laser diodes (LD) or

light emitting diodes (LED) are used

(mainly semiconductor lasers). The

choice between LED and LD is

determined by standard factors that

influence price and performance as

known from traditional optical

communications.

12750 nm 1550 nm

Channel model

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AT RECIEVER:An optical concentrator ( collect

and concentrate incoming radiation) and an

optical filter (to reject ambient light), a

photo detector (PD, to convert radiation/

optical power into a photocurrent), and an

electrical front-end

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LINK DESIGNThere are two basic link designs:

Directed line-of-sight (LOS) :

The beam of a directed link travels from a narrow-beam Tx

to a narrow field-of-view (FOV) receiver(Rx) via the LOS.

Diffuse link:

Communication between a wide-beam Tx and a wide FOV

Rx relies on numerous signal reflections off the surfaces in

the room, instead of a LOS.

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Free Space Optic Link Equation:

HerePreceived = Received PowerPtransmit = Tranmitted PowerAreceiver = Area of the Receiver

Div = Divergence of the beam (in rad)Range = Link length

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LAST MILE BOTTLENECKS

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SECURITY ISSUE

The laser beams generated by FSO system are narrow and invisible making them harder to find and even harder to intercept and crack.

In FSO N-slit interferometric pattern is used which prevent the signal from collapsing therefore received data is more secured.

It improved electromagnetic interference.

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Signal Propagation Impediments:

ABSORPTION SCATTERING FOG SCINTILLATION SOLAR INTERFERENCE DISPERSION BUILDING MOTION SAFETY PHYSICAL OBSTRUCTRIONS

Challenges

Environmental factorsSunlight

Building Motion

Alignment

WindowAttenuation

Fog

Each of these factors can “attenuate” (reduce) the signal. However, there are ways to mitigate each environmental factor.

Scintillation

RangeObstructions

Low Clouds

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ADVANTAGES

Easy to install & installation cost is low.

License free long range operation.

Full duplex operation. Low bit error rate. Highly secure

transmission possible. Possible to mount

inside the building

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DISADVANTAGES

Beam dispersion Atmospheric absorption Rain Fog Snow Pollution / smog Limited bandwidth Solar interfacing

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APPLICATIONS Used where fiber communication is not possible. LAN-to-LAN connections on campuses at Fast

Ethernet or Gigabit Ethernet speeds. LAN-to-LAN connections in a city, a metropolitan

area network. As an alternative or upgrade add-on

to existing wireless technologies For communications between

spacecraft .

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Manufacturers/ Players in the Field of FSO:

LightPointe: A San Diego based company which received contributions from Cisco Systems and Corning to the tune of $33 million. It has raised a total of $51.5 million.

AirFiber: Another San Diego based company which has received contributions from Nortel Networks to the tune of $50 million. It has raised a total of $92.5 million.

Terabeam: A Kirkland, WA based company has received funding from Luscent technologies to the tune of $450 million and has raised $585 million to date.

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Conclusion

FSO networks can be rapidly deployed to provide immediate service to the customers. Some believe that it may be the unlimited bandwidth solution for the metro urban core of downtown building-to-building communication, as well as the optimal technology for home-to-home and office-to-office connectivity. FSO adds the wireless feature to the OFC and thus provides the high bandwidth requirements.

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REFERENCES

http://www.ieee.org

http://www.spacephotonics.com

http://www.lightpointe.com

http://www.freespaceoptics.org

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Thank you &Queries