Transcript NetLight Introduction to FSO Tecnology © Copyright Netronics Inc. Why Free Space Optics (FSO)?

NetLight Introduction to
FSO Tecnology
2008
© Copyright Netronics Inc.
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Why Free Space Optics (FSO)?
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Why Free Space Optics (FSO)?
I - What is FSO
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.
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Why Free Space Optics (FSO)?
The “Last Mile” Bottleneck Problem
Local Area Networks in buildings
are also fast
• >100Mbps
Wide Area Networks between major
cities are extremely fast
• Fiber based
• >2.5 Gbps
The connections in
between are typically a
lot slower
• 0.3-1.5 Mbps
Only about 10% of commercial
buildings are lit with fiber
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Why Free Space Optics?
Why Not Just Bury More Fiber?
Cost
Rights of Way
Permits
Trenching
Time
With FSO, especially through the
window, no permits,
no digging, no fees
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Examples of FSO Systems
Satellite
Lasercom
Terminal
Commercial Lasercom
1 Gbps
2000 km range
Ground
Lasercom
Terminal
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Netronics Communications:
More than 7000 links installed
Worldwide Installations
USA Canada
Mexico Brazil
Argentina
Uruguay
China
Singapore
Japan
India
Philippines
Taiwan
S. Korea
Australia
Thailand
Vietnam
Malaysia
Indonesia
South Africa
Nigeria
Slovenia Croatia Latvia Czechoslovakia Gibraltar Luxemburg Netherlands France Norway
Greece Germany England Switzerland Sweden Portugal Spain Italy Turkey Israel Saudi Arabia
III – The Technology
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103
Hertz
Frequency
104
105
kHz
Power & Telephone
105
108
109
MHz
104
km
103
Laser
communication
GHz
THz
Microwaves
meter
102 10
1010 1011 1012 1013 1014 1015 1016 1017
1
cm
0.1
mm
Infrared
UV
mm
nm
10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9
Coaxial
cable
Copper wire
transmission
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107
Radio Waves
Wavelength
107
106
Smaller carrier wavelength / Higher Bandwidth
Fiber optic
AM radio
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Spread spectrum
Microwave
Electromagnetic Spectrum
Unlicensed
FM radio
8
9
Near Infrared
Visible Spectrum
400 nm
500 nm
600 nm
700 nm
800 nm
900 nm
Near Infrared
HeNe
780 810 850
nm nm nm
1300
nm
1550
nm
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How does it work?
Network
Free space
Fiber Optic
Cable
Receiver
Laser
Transmitter
Network
Lens
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How FSO works?
2 Transmitter projects the
carefully aimed light pulses
into the air
3 A receiver at the other end of the
link collects the light using lenses
and/or mirrors
5 Reverse direction data
transported the same way.
• Full duplex
1 Network traffic
converted into
pulses of invisible
light representing
1’s and 0’s
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
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IV - Free Space
Optics Positioning
High Bandwidth Wireless
Secure Wireless
Short distances
Within Urban areas
Eye safe
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Bandwidth - 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
Netronics Leading the Gigabit Wireless Revolution
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Bandwidth - Wireless?
10 Gbps
Fiber
Future Performances
1 Gbps
Optical Wireless
100 Mbps
c
LMDS
10 Mbps
1 Mbps
WiFi
DSL
50 m
200 m
500 m
T-1
1 km
5 km
15 km+
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Security 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?
Is NetLight FSO signal secure ?
Very narrow and directional mrad divergence
~2 m
Range = R = 1000 m = 1 km
FSO ≡ Most Secure Wireless Solutions
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Narrow Beam Advantages
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
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Applications
Point-to-Point
Secure Ultra Bandwidth
Wireless Mesh
Ring
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V - General Terms
Beam Divergence - measure of angle or how much the beam spreads
circle: 360° (degrees) = 2π radians
1 radian = 57° (degrees)
1 milliradian = 0.001 rad = 0.057° (degree)
80 µ radians = 0.00008 rad = 0.0046° (degree) (satellite)
Range = R = 1000 m = 1 km
Laser Communication System
Laser Communication System
STRV-2 Satellite
2.5 mrad divergence
1 mrad divergence
2.5 m
1m
80 µrad divergence
8 cm
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Link stability – Depending
on Beam divergence
Wide angle
Tx
High geometric loss. . .
. . .good link stability.
Narrow angle
Tx
. . .poor link stability.
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Geometric loss
Receiver Lens
Area
Beam Area
dB
Tx

dR
R (air transmission distance)
= divergence angle,
dB =  R
GM (Geometric Loss) = 10 log (Rx lens Area/Beam Area)
= 10 log [dR /(  R )]2
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The 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
1000
+20 db
100
+10 db
10
0 db
1
-10 db
.1
-20 db
.01
-30 db
.001
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Link Budget
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
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Environmental factors
Sunlight
Window
Attenuation
Fog
Building
Motion
Alignment
Scintillation
Obstructions
Range
Low Clouds
Each of these factors can “attenuate” (reduce) the signal.
However, there are ways to mitigate each environmental factor.
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Environmental effects – Rain,
Scintillation & Haze
Type of events
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Fade Margin calculation
Fade Margin Calculation for :
Fade Margin
TS5000/155
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 :
distance [m]
2000
beam
divergence
[mrad]
2
2 Calculate the area of the receiver on the link head :
beam
diam. [m]
beam area
[cm2]
4.000
125664
RX
diameter
[cm]
22.4
No of
RXs
1
RXs total
Area [cm2]
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.
- Transmit Total Power
- Receiver sensitivity
- Total Available System Gain
Calculate the power in dbm
19.87 dbm
power mW
-45.00 dbm
95
64.87 dbm
dbm
19.78
158.49
22.0
To Calculate Distance Dependant Loss.
- Total Link Length
2000 m@ 0.5 dB/Km
- Divergence Geometric Loss
2000 m
-1 db
-25.036 db
- Total Link Loss
-26.036 db
To Calculate Fixed Loss.
- Equipment Loss (beam loss, mis-alignment, lenses...)
- Scintillation Loss
2000 m@ 1 dB/Km
- Total Equipment Loss
-2 db
-8.00 db
Total system losses@ 2000
Calculated Fade Margin
-6.00 db
@ 2000m
-34.04 db
30.83 db
15.42 db/Km
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VI – Effects of the weather
on FSO com.
Effects of the atmosphere on laser beam propagation
Atmospheric attenuation
absorption
scattering
Atmospheric turbulence
laser beam wander
scintillation
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Environmental effects–Scattering,
Scintillation & Turbulence
Scattering
Major Factor – Haze, Fog, Smog
Scintillation
Moderate Factor - Air shimmering off hot surfaces
Turbulence / Beam Wander
Minor Factor – Different density air layers formed locally
by temperature differences
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Scattering
Typical Scattering Attenuation Factors
for Various Weather Conditions
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Effective 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
SNOW
RAIN
FOG
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Scintillation & Turbulence
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 destroyed
as 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
Transmitter
Receiver
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
Scintillation & Turbulence
Receive power
Laser Beam Wander
Power
Power
Transmit power
Time
Scintillation
Power
Time
Power
Time
Time
Total Effect is the sum of both
Power
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Time
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Scintillation caused
burst errors
Serial bit stream
Fluctuating received laser power
Minimum receive power threshold
Burst error
Burst error
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Link Bandwidth vs. Link Range @
various Atmospheric
attenuation values
Bandwidth
1.25Gbps
NetLight G-3500
100Mbps
NetLight 155-5400
10Mbps
Ethernet/4E1
2Mbps
E1
@
*
*
@
*
*
1 km
@
@
2 km
3 km
4 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.
5 km
6 km
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VII - 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 - Netronics NetLight™
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Series - Matrix
The Most Comprehensive Free Space Optics Solutions
In The Industry
Distances
100Mbps
(Fast-Ethernet)
1-155Mbps
1.25Gbps
(Giga-Ethernet)
Fast Ethrnet
155
Gigabit
Short
Meduim
Long
NetLight 100-800
NetLight 155-1900
NetLight G-1000
NetLight 155-1900
NetLight G2300
NetLight 155-5400
NetLight G-3500
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IX – TS Installation Examples
NetLight G-3500 Datec
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DisneyLand - France
NetLight with Fusion
M6- France
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Yanisahra - Turkey
Sofdit, 7m pole - France
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Vitrolles – France
10 links
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X - NetLight Structure
A - BLOCK DIAGRAM
Control
Panel
RSM-DC
(Option)
Data
Out
Data In
1-155Mbps
Interface unit
Clock / Data
Recovery
Air Link
Transmitter
AC / DC
Power
Supply
Interface
Management
Unit(optional)
Air Link
Receiver
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B - BLOCK DIAGRAM
E1/T1 Line
Interface unit
E1/T1 Line
Interface unit
E1/T1 Line
Interface unit
E1/T1 Line
Interface unit
Control
Panel
4 E1/T1
Multiplexer /
Demultiplexer
Device
Clock/Data
Recovery
Management
Unit (optional)
Air Link
Transmitter
AC/DC
Power
Supply
Air Link
Receiver
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XI - Summary
Advantages of Infrared Wireless links
Very high bandwidth (1.5GBps)
License free
Most secure wireless medium
RFI/EMI immunity
No cross-talk or cross interference
Safe, no health hazards
Easy to relocate links
Low maintenance
Fast deployment
Thank You
© Copyright Netronics Inc.