Free space optics (fso) seminar report full

Free Space Optics

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A

SEMINAR REPORT

ON

“Screenless Display Technology”

As a Partial Fulfillment

For The Degree of Bachelor of Engineering in

Computer Science & Engineering

3rdYear (5thSemester)

YEAR: - 2014

Guided By: Prepared By:

Prof. Chandani A Naik Dilip j. Prajapati

Faculty of Engineering Technology & Research, Isroli-Bardoli

Department of Computer Science & Engineering

Free Space Optics

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Certificate

This is to Certified that the seminar entitled FREE SPACE OPTICS carried out by

Mr. Dilip J. Prajapati PEN 130843131016 in partial fulfillments for the award of

Bachelor of Engineering in Computer Science & Engineering of Faculty of

Engineering Technology & Research, Isroli-Bardoli during the Academic year

2014-2015. It is certified that all corrections/suggestions indicated for Internal

Assessment have been incorporated in the Report. The seminar report has been

approved as it satisfies the academic requirements in respect of seminar work

prescribed for the said Degree.

Seminar Guide H. O. D.

Prof. C A Naik Prof. B R Bhatt

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ACKNOWLEDGEMENT

I would like to take this opportunity to best my acknowledgements to all the

persons who have directly or indirectly been involved with me in making my seminar

feasible and to run it up into a successful piece of work.

A report as all encompassing as this is never the work of one or two people

laboring in quiet solitude. It is the product of many hands, and countless hours from

many people. My thanks go to all those who helped, whether through their comments,

feedback, edits or suggestions. I express a deep sense of gratitude to the Head of the

Computer Science and Engineering Department, Prof. Bhavini R Bhatt and guide

Prof. Chandani A Naik who has helped me throughout my seminar.

How can I forget my college? Without whom I can’t do anything. I would like

to thank my management for their invaluable support. Their patience, understanding

and love gave us strength and will power to work through the long tedious hours in

studying the subject and preparing the report.

Last but not the least, I would also like to thank my friends and classmates

who co-operated during the preparation of my seminar report and without them this

report has not been possible. Their ideas helped me a lot to improve my project

report.

Dilip J. Prajapati

130843131016

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ABSTRACT

Free Space Optics (FSO) or Optical Wireless, refers to the transmission of

modulated visible or infrared (IR) beams through the air to obtain optical

communications. Like fiber, Free Space Optics (FSO) uses lasers to transmit data, but

instead of enclosing the data stream in a glass fiber, it is transmitted through the air. It

is a secure, cost-effective alternative to other wireless connectivity options. This form

of delivering communication has a lot of compelling advantages.

Data rates comparable to fiber transmission can be carried with very low error

rates, while the extremely narrow laser beam widths ensure that it is possible to co-

locate multiple transceivers without risk of mutual interference in a given location.

FSO has roles to play as primary access medium and backup technology. It could also

be the solution for high speed residential access. Though this technology sprang into

being, its applications are wide and many. It indeed is the technology of the future.

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INDEX

Sr. No.TITLE Page No.

ABSTRACT

1 INTRODUCTION1

1.1 DEFINIATION1

2 HISTROY2

3 HOW FREE SPACE OPTICS (FSO) WORKS 3

3.1 OPTICAL COMMUNICATION 5

3.2FSO: Wireless, at the Speed of Light 5

4 FSO ARCHITECTURES 6

4.1 POINT TO POINT 6

4.2 MESH ARCHITECTURE 6

4.3 POINT TO MULTIPOINT ARCHITECTURE 7

5 WHY FSO?8

6 APPLICATION OF FSO9

7 ADVANTAGES OF FSO11

8FREE SPACE OPTICS (FSO) SECURITY12

9 FSO CHALLENGES 13

10 CONCULSION16

REFRENCES 18

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LIST OF FIGURES

FIG. NO. TITLE PAGE NO.

3 (A) FSO WORKING 3

3 (B) FSO SUBSYSTEM WORK 4

3 (C) THE COMPONENTS OF A SENSOR NODE 5

4 (A) POINT TO POINT ARCHITECTURE 6

4 (B) MESH ARCHITECTURE 6

4 (C) POINT TO MULTIPOINT ARCHITECTURE 7

9 (A) FOG 14

9 (B) SCINTILLATION 15

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Chapter 1

Introduction

Free Space Optics (FSO) communications, also called Free Space

Photonics (FSP) or Optical Wireless, refers to the transmission of modulated

visible or infrared (IR) beams through the atmosphere to obtain optical

communications. Like fiber, Free Space Optics (FSO) uses lasers to transmit

data, but instead of enclosing the data stream in a glass fiber, it is transmitted

through the air. Free Space Optics (FSO) works on the same basic principle

as Infrared television remote controls, wireless keyboards or wireless Palm

devices.

1.1 Definition

Free space optics or FSO, free space photonics or optical wireless, refers to the

transmission of modulated visible or infrared beams through the atmosphere to obtain

optical communication. FSO systems can function over distances of several

kilometers.

FSO is a line-of-sight technology, which enables optical transmission up to

2.5 Gbps of data, voice and video communications, allowing optical connectivity

without deploying fiber optic cable or securing spectrum licenses. Free space optics

require light, which can be focused by using either light emitting diodes (LED) or

LASERS(light amplification by stimulated emission of radiation). The use of lasers is

a simple concept similar to optical transmissions using fiber-optic cables, the only

difference being the medium.

As long as there is a clear line of sight between the source and the destination

and enough transmitter power, communication is possible virtually at the speed of

light. Because light travels through air faster than it does through glass, so it is fair to

classify FSO as optical communications at the speed of light.

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Chapter 2

History

The engineering maturity of Free Space Optics (FSO) is often

underestimated, due to a misunderstanding of how long Free Space Optics

(FSO) systems have been under development. Historically, Free Space Optics

(FSO) or optical wireless communications was first demonstrated by

Alexander Graham Bell in the late nineteenth century (prior to his

demonstration of the telephone!). Bell’s Free Space Optics (FSO) experiment

converted voice sounds into telephone signals and transmitted them between

receivers through free air space along a beam of light for a distance of some

600 feet. Calling his experimental device the “photophone,” Bell considered

this optical technology – and not the telephone – his preeminent invention

because it did not require wires for transmission.

Although Bell’s photophone never became a commercial reality, it

demonstrated the basic principle of optical communications. Essentially all of

the engineering of today’s Free Space Optics (FSO) or free space optical

communications systems was done over the past 40 years or so, mostly for

defense applications. By addressing the principal engineering challenges of

Free Space Optics (FSO), this aerospace/defense activity established a strong

foundation upon which today’s commercial laser-based Free Space Optics

(FSO) systems are based.

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Chapter 3

How Free Space Optics (FSO) Works

Optical systems work in the infrared or near infrared region of light and the

easiest way to visualize how the work is imagine, two points interconnected with fiber

optic cable and then remove the cable. The infrared carrier used for transmitting the

signal is generated either by a high power LED or a laser diode. Two parallel beams

are used, one for transmission and one for reception, taking a standard data, voice or

video signal, converting it to a digital format and transmitting it through free space.

Today’s modern laser system provide network connectivity at speed of 622

Mega bits/sec and beyond with total reliability. The beams are kept very narrow to

ensure that it does not interfere with other FSO beams. The receive detectors are

either PIN diodes or avalanche photodiodes.

Fig. 3 (A):- FSO Working

The FSO transmits invisible eye safe light beams from transmitter to the

receiver using low power infrared lasers in the tera hertz spectrum. FSO can function

over kilometers.

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Wavelength:

Currently available FSO hardware is of two types based on the operating

wavelength – 800 nm(nanometer) and 1550 nm. 1550 FSO systems are selected

because of more eye safety, reduced solar background radiation and

compatibility with existing technology infrastructure.

Subsystem:

Fig. 3(B):- FSO Subsystem work

In the transmitting section, the data is given to the modulator for modulating

signal and the driver is for activating the laser. In the receiver section the optical

signal is detected and it is converted to electrical signal, preamplifier is used to

amplify the signal and then given to demodulator for getting original signal. Tracking

system which determines the path of the beam and there is special detector (CCD,

CMOS) for detecting the signal and given to pre amplifier. The servo system is used

for controlling system, the signal coming from the path to the processor and compares

with the environmental condition, if there is any change in the signal then the servo

system is used to correct the signal.

Modulator Driver

Laser Transmit optic

Data in

De-Modulator preamplifier

detector Receive optic

Data out

preamplifier

Special detector

Tracking optic

Processor Servo systems

Environmental

condition

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3.1 Optical Communication

Optical communication is any form of telecommunication that uses light as the

transmission medium.An optical communication system consists of a transmitter,

which encodes amessageinto an optical signal, a channel, which carries the signal to

itsdestination, and a receiver, which reproduces the message from the received

optical signal.

Fig. 3.1(C): - Optical communication

3.2 FSO: Wireless, At the Speed of Light

Unlike radio and microwave systems, Free Space Optics (FSO) is an

optical technology and no spectrum licensing or frequency coordination with

other users is required, interference from or to other systems or equipment is not

a concern, and the point-to-point laser signal is extremely difficult to intercept,

and therefore secure. Data rates comparable to optical fiber transmission can be

carried by Free Space Optics (FSO) systems with very low error rates, while the

extremely narrow laser beam widths ensure that there is almost no practical limit

to the number of separate Free Space Optics (FSO) links that can be installed in

a given location.

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Chapter 4

FSO Architectures

4.1 Point-To-Point Architecture

Point-to-point architecture is a dedicated connection that offers higher

bandwidth but is less scalable .In a point-to-point configuration, FSO can support

speeds between 155Mbits/sec and 10Gbits/sec at a distance of 2 kilometers (km) to

4km. “Access” claims it can deliver 10Gbits/ sec. “Terabeam” can provide up to

2Gbits/sec now, while “AirFiber” and “Lightpointe” have promised Gigabit Ethernet

capabilities sometime in 2001..

Fig 4 (A):- Point to Point Architecture

4.2 Mesh Architecture

Mesh architectures may offer redundancy and higher reliability with easy node

addition but restrict distances more than the other options.

Fig. 4 (B):- Mesh Architecture

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A meshed configuration can support 622Mbits/sec at a distance of 200 meters

(m) to 450m. TeraBeam claims to have successfully tested 160Gbit/sec speeds in its

lab, but such speeds in the real world are surely a year or two off.

4.3 Point-.To-Multipoint Architecture

Point-to-multipoint architecture offers cheaper connections and facilitates

node addition but at the expense of lower bandwidth than the point-to-point option.

Fig 4 (c):- Point to multipoint Architecture

In a point-to-multipoint arrangement, FSO can support the same speeds as the

point-to-point arrangement -155Mbits/sec to 10Gbits/sec-at 1km to 2km.

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Chapter 5

Why FSO?

The increasing demand for high bandwidth in metro networks is relentless,

and service providers' pursuit of a range of applications, including metro network

extension, enterprise LAN-to-LAN connectivity, wireless backhaul and LMDS

supplement has created an imbalance. This imbalance is often referred to as the

"last mile bottleneck." Service providers are faced with the need to turn up

services quickly and cost-effectively at a time when capital expenditures are

constrained. But the last mile bottleneck is only part of a larger problem. Similar

issues exist in other parts of the metro networks. "Connectivity bottleneck" better

addresses the core dilemma. As any network planner will tell you, the connectivity

bottleneck is everywhere in metro networks.

From a technology standpoint, there are several options to address this

"connectivity bottleneck," but most don't make economic sense.

The first, most obvious choice is fiber-optic cable. Without a doubt, fiber is the

most reliable means of providing optical communications. But the digging, delays

and associated costs to lay fiber often make it economically prohibitive. Moreover,

once fiber is deployed, it becomes a "sunk" cost and cannot be re-deployed if a

customer relocates or switches to a competing service provider, making it

extremely difficult to recover the investment in a reasonable timeframe.

Another option is radio frequency (RF) technology. RF is a mature technology that

offers longer ranges distances than FSO, but RF-based networks require immense

capital investments to acquire spectrum license. Yet, RF technologies cannot scale

to optical capacities of 2.5 gigabits. The current RF bandwidth ceiling is 622

megabits. When compared to FSO, RF does not make economic sense for service

providers looking to extend optical networks.

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The third alternative is wire- and copper-based technologies, (i.e. cable modem,

T1s or DSL). Although copper infrastructure is available almost everywhere and

the percentage of buildings connected to copper is much higher than fiber, it is still

not a viable alternative for solving the connectivity bottleneck. The biggest hurdle

is bandwidth scalability. Copper technologies may ease some short-term pain, but

the bandwidth limitations of 2 megabits to 3 megabits make them a marginal

solution, even on a good day.

The fourth-and often most viable-alternative is FSO. The technology is an optimal

solution, given its optical base, bandwidth scalability, speed of deployment (hours

versus weeks or months), re-deployment and portability, and cost-effectiveness

(on average, one-fifth the cost of installing fiber-optic cable).

Only 5 percent of the buildings in the United States are connected to fiber-optic

infrastructure (backbone), yet 75 percent are within one mile of fiber. As

bandwidth demands increase and businesses turn to high-speed LANs, it becomes

more frustrating to be connected to the outside world through lower-speed

connections such as DSL, cable modems or T1s. Most of the recent trenching to

lay fiber has been to improve the metro core (backbone), while the metro access

and edge have completely been ignored. Studies show that disconnects occurs in

the metro network core, primarily due to cost constraints and the deployment of

such non-scalable, non-optical technologies such as LMDS. Metro optical

networks have not yet delivered on their promise. High capacity at affordable

prices still eludes the ultimate end-user.

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Chapter 6

Applications of FSO

Optical communication systems are becoming more and more popular as

the interest and requirement in high capacity and long distance space communications

grow. FSO overcomes the last mile access bottleneck by sending high bit rate signals

through the air using laser transmission.

Applications of FSO system are many and varied but a few can be listed.

1. Metro Area Network (MAN): FSO network can close the gap between

the last mile customers, there by providing access to new customers to high

speed MAN’s resulting to Metro Network extension.

2. Last Mile Access: End users can be connected to high speed links using

FSO. It can also be used to bypass local loop systems to provide business with

high speed connections.

3. Enterprise connectivity: As FSO links can be installed with ease, they

provide a natural method of interconnecting LAN segments that are housed in

buildings separated by public streets or other right-of-way property.

4. Fiber backup: FSO can also be deployed in redundant links to backup

fiber in place of a second fiber link.

5. Backhaul: FSO can be used to carry cellular telephone traffic from antenna

towers back to facilities wired into the public switched telephone network.

6. Service acceleration: Instant services to the customers before fiber being

laid.

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Chapter 7

Advantages of FSO

Free space optical (FSO) systems offer a flexible networking solution

that delivers on the promise of broadband. Only free space optics or Free

Space Optics (FSO) provides the essential combination of qualities required

to bring the traffic to the optical fiber backbone – virtually unlimited

bandwidth, low cost, ease and speed of deployment. Freedom from licensing

and regulation translates into ease, speed and low cost of deployment. Since

Free Space Optics (FSO) optical wireless transceivers can transmit and

receive through windows, it is possible to mount Free Space Optics (FSO)

systems inside buildings, reducing the need to compete for roof space,

simplifying wiring and cabling, and permitting the equipment to operate in a

very favorable environment. The only essential for Free Space Optics (FSO)

is line of sight between the two ends of the link.

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Chapter 8

Free Space Optics (FSO) Security

Security is an important element of data transmission, irrespective of the

network topology. It is especially important for military and corporate applications.

Building a network on the SONA beam platform is one of the best ways to ensure that

data transmission between any two points is completely secure. Its focused

transmission beam foils jammers and eavesdroppers and enhances security. Moreover,

fSONA systems can use any signal-scrambling technology that optical fiber can use.

The common perception of wireless is that it offers less security than wire line

connections. In fact, Free Space Optics (FSO) is far more secure than RF or

other wireless-based transmission technologies for several reasons:

Free Space Optics (FSO) laser beams cannot be detected with

spectrum analyzers or RF meters.

Free Space Optics (FSO) laser transmissions are optical and travel

along a line of sight path that cannot be intercepted easily. It

requires a matching Free Space Optics (FSO) transceiver carefully

aligned to complete the transmission. Interception is very difficult

and extremely unlikely.

The laser beams generated by Free Space Optics (FSO) systems

are narrow and invisible, making them harder to find and even

harder to intercept and crack.

Data can be transmitted over an encrypted connection adding to

the degree of security available in Free Space Optics (FSO)

network transmissions.

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Chapter 9

FSO Challenges

The advantages of free space optical wireless or Free Space Optics (FSO)

do not come without some cost. When light is transmitted through optical fiber,

transmission integrity is quite predictable – barring unforeseen (unexpected)

events such as backhoes or animal interference. When light is transmitted

through the air, as with Free Space Optics (FSO) optical wireless systems, it

must contend with a complex and not always quantifiable subject - the

atmosphere.

1. FOG

Fig. 9 (A):- Fog

Fog substantially attenuates visible radiation, and it has a similar affect on the near-

infrared wavelengths that are employed in FSO systems. Rain and snow have little

effect on FSO. Fog being microns in diameter, it hinder the passage of light by

absorption, scattering and reflection. Dealing with fog – which is known as Mie –

scattering, is largely a matter of boosting the transmitted power. Fog can be countered

by a network design with short FSO link distances. FSO installation in foggy cities

like San Francisco has successfully achieved carrier-class reliability.

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2. Physical Obstructions

Flying birds can temporarily block a single beam, but this tends to cause

only short interruptions and transmissions are easily and automatically re-assumed.

Multi-beam systems are used for better performance.

3. Scintillation

Fig. 9(A):-Scintillation

Scintillation refers the variations in light intensity caused by atmospheric

turbulence. Such turbulence may be caused by wind and temperature gradients

which results in air pockets of varying diversity act as prisms or lenses with time

varying properties. This scintillation affects on FSO can be tackled by multi

beam approach exploiting multiple regions of space- this approach is called

spatial diversity.

4. Solar Interference

This can be combated in two ways:

The first is a long pass optical filter window used to block all wavelengths

below 850nm(nenometre) from entering the system.

The second is an optical narrow band filter proceeding the receive detector

used to filter all but the wavelength actually used for intersystem

communications.

5. Scattering

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Scattering is caused when the wavelength collides with the scatterer. The physical

size of the scatterer determines the type of scattering.

When the scatterer is smaller than the wavelength-Rayleigh scattering.

When the scatterer is of comparable size to the wavelength -Mie

scattering.

When the scatterer is much larger than the wavelength-Non-selective

scattering

In scattering there is no loss of energy, only a directional re-distribution of energy

which may cause reduction in beam intensity for longer distance.

6. Absorption

Absorption occurs when suspended water molecules in the terrestrial atmosphere

extinguish photons. This causes a decrease in the power density of the FSO beam and

directly affects the availability of a system. Absorption occurs more readily at some

wavelengths than others.

However, the use of appropriate power, based on atmospheric conditions, and use of

spatial diversity helps to maintain the required level of network availability.

7. Building Sway / Seismic Activity

One of the most common difficulties that arises when deploying FSO links on

tall buildings or towers is sway due to wind or seismic activity Both storms and

earthquakes can cause buildings to move enough to affect beam aiming. The

problem can be dealt with in two complementary ways: through beam

divergence and active tracking

With beam divergence, the transmitted beam spread, forming optical

cones which can take many perturbations.

Active tracking is based on movable mirrors that control the direction in

which beams are launched.

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Chapter 10

Conclusion

FSO enables optical transmission of voice video and data through air at very

high rates. It has key roles to play as primary access medium and backup technology.

Driven by the need for high speed local loop connectivity and the cost and the

difficulties of deploying fiber, the interest in FSO has certainly picked up dramatically

among service providers world wide. Instead of fiber coaxial systems, fiber laser

systems may turn out to be the best way to deliver high data rates to your home. FSO

continues to accelerate the vision of all optical networks cost effectively, reliably and

quickly with freedom and flexibility of deployment.

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Reference

1. Vikrant kaulgnd, “Free space optics Bridges the last mile’’ ,Electronics

for u , June 2003 pp . 38-40 .

2. Andy Emmerson , “ Fibreless Optics ’’ , Everyday practical electronics

, April 2003 pp . 248 .

Websites:

3. www.fsona.com

4. www.freespaceoptics.com

5. www.freespaceoptic.com

6. www.fsocentral.com

7. www.lightpointe.com

8. www.spie.org

9. www.osa.org