Free space Communication

1

Supervised by:

Prof. Magdy Ibrahim

Prepared by:

Ahmed Ashraf Abdel-Haseb

Ahmed-Houssam Mahmoud

Ahmed Magdy El-Sayed

Amr Atef Hussein

Mohamed Khaled Abo-Seif

Free Space Optical Communication (FSO)

2

Supervised by:

Prof. Magdy Ibrahim

Prepared by:

Ahmed Ashraf Abdel-Haseb

Ahmed-Houssam Mahmoud

Ahmed Magdy El-Sayed

Amr Atef Hussein

Mohamed Khaled Abo-Seif

Free Space Optical Communication (FSO)

• Introduction [1]

• Free Space Optical Link Design [2]

• Applications [3]

• FSO vs. Fiber vs. Microwave Links

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Outlines





4

Outlines

• Operation of FSO

• Uses

• Advantages and Disadvantages

• Security Aspects

• Safety Aspects

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Introduction


• Uses



• Safety Aspects

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Introduction


• Uses• To cross a public road or other barriers which the

sender and receiver do not own.

• For communications between spacecraft.

• Speedy service delivery of high-bandwidth access to optical fiber networks.



• Safety Aspects

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Introduction


• Uses

• Advantages and DisadvantagesAdvantages• License-free operation.• High bit rates.• Low bit error rates.• Immunity to electromagnetic interference.• Security.• Easiness and speed of installation.


• Safety Aspects

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Introduction


• Uses

• Advantages and DisadvantagesDisadvantages• Beam dispersion.• Atmospheric absorption.• Rain, Snow, Fog (10..~100 dB/km attenuation).• Background light.


• Safety Aspects

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Introduction


• Uses



• Safety Aspects

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Introduction


• Applications



• Safety Aspects• Eye Damage

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Introduction





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Outlines

• FSO Subsystems

• FSO Link Equation and Link Budget

• Theoretical Range Limit

• BER, Data Rate, and Range

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Free Space Optical Link Design

• FSO Subsystems

1. Transmitter

2. Receiver

3. Tracking System




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• FSO Subsystems

1. Transmitter

2. Receiver

3. Tracking System

• Requirements:

Tracking Frequency, Resolution, Speed, … etc.




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• FSO Subsystems

• FSO Link Equation and Link BudgetLink Equation:

Link Budget:



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• FSO Subsystems


• Theoretical Range Limit• Assume Perfect Components (no thermal Noise)• For : =>


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• FSO Subsystems




.

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Outlines

Free Space Optical Networks

• Point to Point FSO Systems

• Mesh FSO Systems

FSO on HAPs (Future Application)

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Applications

Free Space Optical Networks • Point to Point FSO Systems



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Applications

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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 FSO26

Applications

Free Space Optical Networks • Point to Point FSO Systems

Disadvantages• Cannot connect more than 2 points

• The points cannot have arbitrary distance between them

• Has the poorest network and traffic protection



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Applications

Free Space Optical Networks • Ring FSO Systems



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Applications

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Nodes of a mesh - FSO topology on fl at terrain but with nodes at different heights.


• Mesh FSO SystemsAdvantages

• The best network and service protection

• Very high data rates

• Scalability and expandability


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Applications


• Mesh FSO SystemsDisadvantages

• The complexity of each node in the mesh topology.

• High Cost


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Applications

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Nodes over a geographical territory with line of sight between them.

Free Space Optical Networks • Ring FSO Systems• Mesh FSO Systems

FSO on HAPs (Future Application)• Use on high altitude platforms (HAPs), (20 –

30 Km).• Estimated Range: more than 600km.

• .

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Applications

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Free Space Optical Networks • Ring FSO Systems• Mesh FSO Systems

FSO on HAPs (Future Application)Advantages:• Stratospheric Conditions.• Low attenuation, no cloud interference, low

tempreture…etc.• Cost Effective (Compared to Satellites)• FSO Advantages• High Data rate, Low Power Consumption …etc.

• .

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Applications





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Outlines

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FSO vs. Fiber vs. Microwave Links

Criteria FSOOptical Fiber

Microwave

Data rate Up to 10 Gbps 100 Mbps to 100 Gbps

275 Mbps

Installation Easy Difficult Moderate

Cost Moderate High Moderate

Maintenance

low High low

Most common

uses

Between buildings

Short distance

Point-to point

Long distance

Point-to-point

Short distance

Advantages

Price

performance

No license

Security

capacity and speed

Immunity to EMI

speed

Disadvantages

Can be intercepted

Difficult to splice determinate

Can be intercepted

Requires radio license

Security Moderate Excellent Poor

[1] S.V. Kartalopoulos , “ Disaster Avoidance in the Manhattan Fiber Distributed Data Interface Network , ” Globecom ’ 93, Houston, TX, December 2, 1993 .

[2] Scott Bloom, “The Physics of Free Space Optics”, AirFiber, Inc.

[3] “Free-Space Optical Communications on HAPs”, www.hapcos.org , accessed on : 13-May-2012

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References

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Thanks

Documents

Free space Communication