Introduction To Fso Technology

Service Aware Networking Technologies TMSlide No. Slide No. 11

By Itshak Kidouchim – Jan 2007


Introduction to FSO – Free Space OpticsIntroduction to FSO – Free Space Optics

• FSO Communication is using the LASER light as the carrier.

• Full Duplex, Full Speed AND No Delay.

• Up to 1 Gbps Ethernet

• Distances – up to 5km.

• No License is required.

• Easy to install and almost no maintenance is required.

I - What is FSOI - What is FSO


II - Why Free Space Optics (FSO)?II - Why Free Space Optics (FSO)?

The “Last Mile” Bottleneck ProblemThe “Last Mile” Bottleneck Problem

II - Why Free Space Optics (FSO)?II - Why Free Space Optics (FSO)?

The “Last Mile” Bottleneck ProblemThe “Last Mile” Bottleneck Problem

Only about 10% of commercial buildings are lit with fiber

Wide Area Networks between major cities are extremely fast

• Fiber based• >2.5 Gbps

Local Area Networks in buildings are also fast

• >100Mbps

The connections in between are typically a lot slower

• 0.3-1.5 Mbps


Why Free Space Optics?Why Free Space Optics?Why Not Just Bury More FiberWhy Not Just Bury More Fiber??

?Why Free Space Optics?Why Free Space OpticsWhy Not Just Bury More FiberWhy Not Just Bury More Fiber??

• Cost

• Rights of Way

• Permits

• Trenching

• Time

With FSO, especially through With FSO, especially through the window, no permits, no the window, no permits, no

digging, no fees digging, no fees


GroundLasercomTerminal

SatelliteLasercomTerminal

1 Gbps2000 km range

Commercial Lasercom

Examples of FSO SystemsExamples of FSO Systems


Worldwide InstallationsUSA Canada Mexico Brazil Argentina Uruguay ChinaSingaporeJapanIndiaPhilippinesTaiwan S. KoreaAustraliaThailandVietnamMalaysiaIndonesia South Africa Nigeria

Slovenia Croatia Latvia Czechoslovakia Gibraltar Luxemburg Netherlands France Norway Greece Germany England Switzerland Sweden Portugal Spain Italy Turkey Israel Saudi Arabia

MRV Communications:MRV Communications:More than 7000 links installedMore than 7000 links installed


Spre

ad s

pect

rum

Micr

owav

e

101 102 103 104 105 106 107 108 109 1010 1011 1012 1013 1014 1015 1016

Hertz kHz MHz GHz THz

107 106 105 104 103 102 10 1 0.1 10-2 10-3 10-4 10-5 10-6 10-7 10-8

Frequency

Wavelength

Radio Waves Microwaves Infrared UVPower & Telephone

Copp

er w

iretra

nsm

issio

n

km meter cm mm mm10-9

nm

1017

Coax

ial

cabl

e

Fibe

r opt

ic

AM ra

dio

FM ra

dio

Lase

rco

mm

unica

tion

Electromagnetic SpectrumElectromagnetic SpectrumUnlicensed

III – The TechnologyIII – The Technology

Smaller carrier wavelength / Higher Bandwidth


Visible Spectrum400 nm 500 nm 600 nm 700 nm 800 nm 900 nm

HeNe 780nm

810nm

850nm

1550nm

Near Infrared

1300nm

Near InfraredNear Infrared


How does it workHow does it work??

Fiber Optic Cable

Fiber Optic Cable

Laser Transmitter

Laser Transmitter

ReceiverReceiver

Network

Network

LensLens

Free spaceFree space


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

4 Received signal converted back into fiber or copper and connected to the network

Anything that can be done in fiber can be done with FSO

How FSO worksHow FSO works??


IV - Free Space Optics PositioningIV - Free Space Optics Positioning

High Bandwidth WirelessHigh Bandwidth Wireless

Secure Wireless Secure Wireless

Short distancesShort distances

Within Urban areasWithin Urban areas

Eye safeEye safe


Bandwidth - WirelessBandwidth - Wireless? ?

• What is the fiber technology bandwidth limitation ?

– Unlimited

• What is the radio technology bandwidth limitation ?– Limited (only GHz frequencies)

• What is the FSO technology bandwidth limitation ?– Unlimited

FSO ≡ Ultra Bandwidth Wireless Solutions

MRV Leading the Gigabit Wireless Revolution


Access Technologies PositioningAccess Technologies Positioning

c

10 Gbps

1 Gbps

100 Mbps

10 Mbps1 Mbps

200 m50 m 500 m 1 km 5 km 15 km+

Fiber

LMDS WiFi

Optical Wireless

T-1DSL

Future Performances


Security WirelessSecurity Wireless ? ?

• Is Radio signal secure ? What is the RF signal spectrum ?

Very wide

How many times did you see other Radio network in your area ?

FSO ≡ Most Secure Wireless Solutions

Very narrow and directional mrad divergence

Range = R = 1000 m = 1 km

~2 m

• Is TereScope FSO signal secure ?


• Beams only a few meters in diameter at a kilometer

• 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

Narrow Beam Advantages Narrow Beam Advantages


ApplicationsApplications

Point-to-Point

Ring

Secure Ultra Bandwidth Wireless Mesh


V - General TermsV - General Terms

Beam DivergenceBeam Divergence - measure of angle or how much the beam spreads

circle: 360° (degrees) = 2π radians1 radian = 57° (degrees)1 milliradian = 0.001 rad = 0.057° (degree)

80 µ radians = 0.00008 rad = 0.0046° (degree) (satellite)

1 radian

Laser Communication System

2.5 mrad divergence

1 mrad divergence

Range = R = 1000 m = 1 km

2.5 m

1 m

80 µrad divergence8 cm

STRV-2 Satellite

Laser Communication System


Tx Tx

High geometric loss. . . . . .good link stability.

Narrow angle

Tx Tx

. . .poor link stability.

Wide angle

Link stabilityLink stability – Depending on Beam divergence


Geometric lossGeometric lossBeam Area

Receiver Lens Area

dB

= divergence angle, dB = R

GM (Geometric Loss) = 10 log (Rx lens Area/Beam Area)

= 10 log [dR /( R )]2

dR

R (air transmission distance)

Tx


The Decibel - dBThe Decibel - dBThe Decibel - dBThe Decibel - dB

• A logarithmic ratio between two values

• In the optical world of Power in mW,

• dB=10*Log(power2/power1)

• 3 dB = ratio of 2/1

• 6 dB = ratio of 4/1

• 10 dB = ratio of 10/1

• 20 dB = ratio of 100/1

• 50 dB= ratio of 100,000/1

Gain/Loss Multiplier

+30 db

+20 db

+10 db

0 db

-10 db

-20 db

-30 db

1000

100

10

1

.1

.01

.001


• System Gain– Transmitter(s) power – Receiver sensitivity

• Attenuation– Geometrical attenuation– Atmospheric attenuation

• Scattering• Scintillation• Turbulence

– System factors• Components and assemblies

tolerances• System misalignment

Total available margins = System Gain - Attenuation

Link BudgetLink Budget


Environmental factorsEnvironmental factorsEnvironmental factorsEnvironmental factors

Sunlight

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

Sunlight


Environmental effects – Rain, Scintillation & HazeEnvironmental effects – Rain, Scintillation & Haze

Type of events


Fade Margin calculationFade Margin calculation

Fade Margin Calculation for :

Fade Margin 30.83 db 15.42 db/Km

Enter values from the data sheets for the specefic TereScope

Fill only the white cells

To Calculate Geometric Loss.

1 Calculate the one of the projected pattern : 2 Calculate the area of the receiver on the link head :

distance [m]beam

divergence [mrad]

beam diam. [m]

beam area [cm2]

RX diameter [cm]

No of RXs

RXs total Area [cm2]

2000 2 4.000 125664 22.4 1 394.1

3 Convert the two areas ratio to dB using the 10 log rule :Geometrical loss [db] -25.036

To Calculate Total Link Budget. Calculate the power in dbm

- Transmit Total Power 19.87 dbm power mW dbm

- Receiver sensitivity -45.00 dbm 95 19.78

- Total Available System Gain 64.87 dbm 158.49 22.0

To Calculate Distance Dependant Loss.

- Total Link Length 2000 m@ 0.5 dB/Km -1 db

- Divergence Geometric Loss 2000 m -25.036 db

- Total Link Loss -26.036 db

To Calculate Fixed Loss.

- Equipment Loss (beam loss, mis-alignment, lenses...) -6.00 db

- Scintillation Loss 2000 m@ 1 dB/Km -2 db

- Total Equipment Loss -8.00 db

Total system losses@ 2000 -34.04 db

Calculated Fade Margin @ 2000m 30.83 db 15.42 db/Km

TS5000/155


Effects of the atmosphere on laser beam propagation

• Atmospheric attenuation• absorption• scattering

• Atmospheric turbulence• laser beam wander• scintillation

VI – Effects of the weather on FSO com.VI – Effects of the weather on FSO com.


Environmental effects – Scattering, Scintillation & TurbulenceEnvironmental effects – Scattering, Scintillation & Turbulence

• ScatteringMajor Factor – Haze, Fog, Smog

• Scintillation Moderate Factor - Air shimmering off hot surfaces

• Turbulence / Beam WanderMinor Factor – Different density air layers formed locally by temperature differences


Typical Scattering Attenuation Factors for Various Weather Conditions

ScatteringScattering


Effective Link Range vs. Winter VisibilityEffective Link Range vs. Winter Visibility

• For laser transmission, attenuation by fog is much greater than attenuation by rain (opposite for microwaves)

• Fog droplet size (5 to 15 µm) laser wavelength

• Rain droplet size (200 to 2000 µm) microwave wavelength

• Effect of snow is between rain and fog

FOGRAINSNOW


Atmospheric turbulence (ie. wind) produce temporary pockets of air with different temperature thus different density thus different index of refraction.These air pockets and are continuously being created and then destroyedas they are mixed. The effect of these cells which lie along the laser beam path depends on the size of the cells.

Laser Beam Wander if the cells are larger than the beam diameter

Scintillation if the cells are smaller than the beam diameter. The wavefront becomes distorted due to constructive and destructive interference creating fluctuations in receive power, similar to the twinkling of a distant star.

Transmitter Receiver

Transmitter Receiver

Scintillation & TurbulenceScintillation & Turbulence


Powe

r

Time

Powe

r

Time

Laser Beam WanderTransmit power Receive power

Powe

r

Time

Powe

r

Time

Scintillation

Total Effect is thesum of both Po

wer

Time

Scintillation & TurbulenceScintillation & Turbulence


Serial bit stream

Fluctuating received laser power

Minimum receive power threshold

Burst error Burst error

Scintillation caused burst errorsScintillation caused burst errors


**

TS5000/G

TS5000/155

Ethernet/4E1

E1

Bandwidth

1 km

1.25Gbps

100Mbps

10Mbps

2Mbps

2 km 3 km 4 km 5 km

*

30 dB/km

17 dB/km

10 dB/km

3 dB/km

@

@

@

* @

For operation under light to medium rain, light snow, light haze.

*

For operation under medium to heavy rain – snow, thin fog.

For operation under cloudburst, medium snow, light fog.

For operation under blizzard, moderate fog.

@

Link Bandwidth vs. Link Range Link Bandwidth vs. Link Range @ @

various Atmospheric attenuation valuesvarious Atmospheric attenuation values

6 km


VII - Competitive TechnologyVII - Competitive Technology

Spread Spectrum Disadvantages Susceptible to RF interference in congested areas Can be monitored easily Limited actual bandwidth (throughput of 2-54 Mbps half duplex)

Microwave Disadvantages Cost (the higher the bandwidth, the greater the cost) Complex installations Licensing required for higher frequencies


VIII - MRV TereScope™ Series - MatrixVIII - MRV TereScope™ Series - Matrix

The Most Comprehensive Free Space Optics SolutionsIn The Industry

Distances Short Meduim Meduim + Long Long+

Data Rate Model Suffix~0.25-0.45 km @ 30db/Km~0.3 - 0.6 km @ 17db/Km~0.3 - 1.2 km @ 3db/Km

~0.6 - 0.75 km @ 30db/Km~0.8 - 1 km @ 17db/Km ~1.5 - 2.7 km @ 3db/Km

~0.8 - 1km @ 30db/Km~1 - 1.5 km @ 17db/Km~3 - 4.1 km @ 3db/Km

~1 - 1.2 km @ 30db/Km~1.5 - 1.8 km @ 17db/Km

~4 - 5.2 km @ 3db/Km

~1.2 - 1.4km @ 30db/Km~1.8 - 2.1 km @ 17db/Km~5.5 - 6.5 km @ 3db/Km

2.048 Mbpsor 1.55 Mbps

E1/T1 TS702 TS707 TS2000 TS4000

4x2.048 Mbpsor 4x1.55 Mbps

4E1/4T1 TS702 TS707 TS2000 TS4000 TS5000

10Mbps(Ethernet)

Ethrnet TS702 TS707 TS4000 TS5000

1-34Mbps(Open Protocol)

34 TS4000

100Mbps (Fast-Ethernet)

Fast Ethrnet TS700 / TS1

1-155Mbps 155 TS700 TS800 TS4000 TS5000

1.25Gbps(Giga-Ethernet)

Gigabit TS700 / TS1000P TS5000


IX – TS Installation ExamplesIX – TS Installation Examples

TS5000 Datec


DisneyLand - France

TS3303 with Fusion

M6- France


Sofdit, 7m pole - France

TS707/4E1, Yanisahra - Turkey



Vitrolles – France

10 links



X - TereScope StructureX - TereScope Structure בס"A - TS155 BLOCK DIAGRAMד

1-155Mbps Interface unit

ControlPanel

ManagementUnit(optional)

Air LinkTransmitter

Air LinkReceiver

AC / DCPowerSupply

Clock / Data Recovery

RSM-DC(Option)

Data Out

Data InInterface


B - 4E1 BLOCK DIAGRAM

E1/T1 Line Interface unit




4 E1/T1Multiplexer /

Demultiplexer

DeviceClock/DataRecovery

ControlPanel

ManagementUnit(optional)

Air LinkTransmitter

Air LinkReceiver

AC / DCPowerSupply


Advantages of Infrared Wireless linksAdvantages of Infrared Wireless links

• Very high bandwidth (1.5GBps)Very high bandwidth (1.5GBps)

• License freeLicense free

• Most secure wireless medium Most secure wireless medium

• RFI/EMI immunityRFI/EMI immunity

• No cross-talk or cross interferenceNo cross-talk or cross interference

• Safe, no health hazardsSafe, no health hazards

• Easy to relocate linksEasy to relocate links

• Low maintenanceLow maintenance

• Fast deploymentFast deployment

XI - SummaryXI - Summary


THANK YOUTHANK YOU

ww.mrv.comww.mrv.com

[email protected]