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INTRODUCTION
TO DWDM
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FIBRE EXHAUST
2.5- Gbit/s
2.5- Gbit/s
2.5- Gbit/s
2.5- Gbit/s
transmitter
2.5-Gbit/s2.5 Gbit/s
2.5 Gbit/s
reciever
LAY NEW FIBRE AND PUT NEW SYSTEMS
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FIBRE EXHAUST
2.5- Gbit/s
2.5- Gbit/s
2.5- Gbit/s
2.5- Gbit/s
transmitter
2.5-Gbit/s
2.5 Gbit/s
2.5 Gbit/s
reciever
INSTAL HIGHER BITRATE TDM
EXPENSIVE, NEW FIBRE NEEDED
10-Gbit/s 10-Gbit/s10-Gbit/s
transmitter regenerator reciever
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FIBRE EXHAUST
DEPLOY DWDM
2.5-Gbitt/s
transmitter
M
U
X
D
E
M
U
X
10-Gbit/s 10-Gbit/s10-Gbit/s
transmitter regenerator reciever
2.5- Gbit/s
2.5- Gbit/s
2.5- Gbit/s
2.5- Gbit/s
2.5- Gbit/s
transmitter
2.5-Gbit/s
2.5 Gbit/s
2.5 Gbit/s
reciever
2.5- Gbit/sreciever
2
1
3
4
2
1
3
4
2.5- Gbit/sreciever
2.5- Gbit/sreciever
2.5- Gbit/sreciever
2.5-Gbitt/stransmitter
2.5-Gbitt/s
transmitter
2.5-Gbitt/s
transmitter
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5
DWDM History
Early WDM (late 80s)
Two widely separated wavelengths (1310, 1550nm)
Second generation WDM (early 90s)
Two to eight channels in 1550 nm window
400+ GHz spacing
DWDM systems (mid 90s)
16 to 40 channels in 1550 nm window
100 to 200 GHz spacing
Next generation DWDM systems
64 to 160 channels in 1550 nm window
50 and 25 GHz spacing
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Overview
Now in use:
C-band1525~1565nm
In research :
L-band 1570~1620nm
S-band 1400nm
In Future, the
communication window1280~1625nm
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ACHIEVING HIGHER BANDWIDTH
THREE POSSIBLE SOLUTIONS
Install new fibre
Invest in new TDMTechnologies to
Achieve higher
Bandwidth.
Deploy DWDM
Expensive
ExpensiveRequire new
Type fibre
Economical
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JUST LIKE WIDENING OF ROAD USING AVAILABE LAND TO MEET INCREASED TRAFFIC
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DWDM BASICS
SINGLE FIBRE
SDH OPTICAL SIGNALS
NEW REQUIREMENTS:
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BLOCK SCHEMATIC
Tx RxMUX DEMUX
OFAWD
M
W
D
M
2.
.
.
.
1
16
TRANSPONDERS
OPTICAL
SIGNALS.
STM-1
STM-4
STM-16
ATM
IP
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Wayside Optical Add/Drop Multiplexer
TM TMWDM
MUX
WDM
DEMU
X2
15
16
1
1-4 5-8
O
A
O
A
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Optical Add/Drop
Multiplexing
1 12 2 2 2
Configurable
OADM :1 or2
1 12 2 2 2
1 1
fixed OADM:
2
OADM : Optical Add/Drop Multiplexer
Terminal Equipt Terminal EquiptIn-Line Amplifier
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DIFFERENCES FROM OLD SYSTEM
REGs
FIBRES REQUIREMENT
LASERS TYPES OF COMPONENTS
CAPACITY
FIBRE TRANSMISSION BEHAVIOUR
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ADVANTAGES OF DWDM
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Transparency Can carry multiple protocols on same fiber
Monitoring can be aware of multiple protocols
Wavelength spacing 50GHz, 100GHz, 200GHz
Defines how many and which wavelengths can be used
Wavelength capacity Example: 1.25Gb/s, 2.5Gb/s, 10Gb/s
Characteristics of a WDM Network
Wavelength Characteristics
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Why Optical (DWDM) Networking?
Fibre Exhaust : Unlimited bandwidth on a fibre pair
Bit Rate Transparency
Format/Protocol Transparency : IP, ATM etc. Efficient use and rearrangement of embedded optical
capacity as per demand.
Minimal Capital Expenditure : Capacity Expansions
Demand
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Economics of WDM
Saving of regeneration costs:
one optical amplifier for many channels regeneration
cost per channel drastically reduced Saving of fibres/fibre shortage
Cost effective compared to laying new fibres
Introduction of a new network layer:
additional planning possibilities by passing of traffic
on nodes reduces node costs
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OPTICAL NETWORK ELEMENTS
TP
TP OA
ODEM
UX
OMUX
OADM OXC
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TRANSPONDER / TRANSLATOR /
WAVELENGTH CONVERTOR
O/E E/OElectricalREGENERATION
OPTIONAL
REGENERATOR
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Transponders
Converts broadband optical signals to a specific wavelength viaoptical to electrical to optical conversion (O-E-O)
Used when Optical LTE (Line Termination Equipment) does nothave tight tolerance ITU optics
Performs 2R or 3R regeneration function
Receive Transponders perform reverse function
Low Cost
IR/SR Optics
Wavelengths
Converted
1
From OpticalOLTE To DWDM MuxOEO
OEO
OEO
2
n
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Optical Amplifier
Advantages:
Design simplicity &high reliability.
Fewer components and economical.
Very low noise level.
Ability to amplify multiple wavelength signals in the operating
band.
No interchannel interference .
Careful design can remove the dispersion
problems also.
E bi D d Fib
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EDF Amplifier Charactertics
1. Highly Efficient
2. High gain
3. Low Noise figure.
4. Low Cost
Erbium Doped Fiber
Amplifier (EDFA)
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Erbium Doped Fiber Amplifier
Simple device consisting of four parts:
Erbium-doped fiber An optical pump
A coupler
An isolator to cut off backpropagating noise
Isolator Coupler IsolatorCoupler
Erbium-Doped
Fiber (1050m)
Pump
Laser
Pump
Laser
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NMS FOR DWDM SYSTEMS
NMS IN CONVENTIONAL SDH SYSTEMS:
DCC: TIME SLOTS
DWDMNO TIME SLOTS
WAVELENGTH SLOTS
ONE WAVELENGTH IS DEDICATED FOR N.M.S.
OPTICAL SUPERVISORY CHANNEL
OSC needs to be accessed at all points in the network
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Optical Supervisory Channel - OSC
OSC mainly carries orderwire and network
management information.
signals at 1510 nm or 1625 nm
2.048 Mb/s
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Optical Supervisory Channel
(OSC)
Line Terminal Equipment In-line Amplifier
Tx 1
Tx 2
Tx 3
Tx 4
Tx 5
Tx 6
Tx 7
Tx 8
D
ATAIN
1
2
3
4
5
6
7
8
Rx
Rx
Rx
Rx
Rx
Rx
Rx
Rx
1
2
3
4
5
6
7
8
Line Terminal Equipment
+ supervisory
Tx sup
System Control
Processor
Rx Tx
OSC
Network Management Network Management
System Control
Processor
Rx sup
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OPTICAL BANDS
EXTENSIVE USE OF WAVELENGTHS
DIFFERENT VENDORS:INTEROPERABILITY ISSUES
NEED FOR STANDARD WAVELENGTH VALUES
ITU Classification of bands
Standard values : ITU Grid
Center frequency: 193.10THz (1552.52 nm)
Standard spacings of 200, 100, 50 GHz for different applications
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ITU-T BAND ALLOCATION
Optical
Supervisory
channel
1500 1520 1530 1542 1547 1560 1620
RED
BAND
C BAND L BAND
BLUE
BAND
CBAND PRODUCTS ARE COMMERCIALLY AVAILABLE.ERBIUM DOPED FIBRE AMPLIFIERS SUITABLE FOR
C BAND.
GAIN IN RED BAND FLATTEST FOR EDFA. SOME MANUFACTURERS PROVIDE 16 CHANNELS IN
RED BAND ONLY. OTHERS USE BOTH RED
& BLUE BANDS.
ITU T G 692 Frequency Grid
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Nominal
Central
(THz)
Central
(nm)
Nominal
Central
(THz)
Central
(nm)
Nominal
Central
(THz)
Central
(nm)
196.1 1528.77 194.7 1539.77 193.3 1550.92
196.0 1529.55 194.6 1540.56 193.2 1551.72
195.9 1530.33 194.5 1541.35 193.1 1552.52
195.8 1531.12 194.4 1542.14 193.0 1553.33
195.7 1531.90 194.3 1542.92 192.9 1554.13
195.6 1532.68 194.2 1543.73 192.8 1554.94
195.5 1533.47 194.1 1544.53 192.7 1555.75
195.4 1534.25 194.0 1545.32 192.6 1556.55
195.3 1535.04 193.9 1546.12 192.5 1557.36
195.2 1535.82 193.8 1546.92 192.4 1558.17
195.1 1536.61 193.7 1547.72 192.3 1558.98
195.0 1537.40 193.6 1548.51 192.2 1559.79
194.9 1538.19 193.5 1549.32 192.1 1560.61
194.8 1539.77 193.4 1550.12
ITUT G.692 Frequency Grid
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LIMITATIONS
THE MAXIMUM DISTANCE IS 640 km, MADE OF 8 SPANS OF 80km The assumptions are:
* Fibre attenuation, including splice loss is 0.28 db/km
* Span loss of 22 db. (0.28 *80km =22.40 )
* Total dispersion is less than 12800 ps/nm.
* For G.652 fiber/ cable is DISPERSION 17/20 ps/nm-km
* For 640 Km dispersion= 12800ps/nm
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Metropolitan Area Network
Unlimited Bandwidth, bit rate and format
transparencyEfficient Bandwidth use and Management
New Applications with DWDM
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Wavelength LeasingNetwork Customers are beginning to demand
high capacity Network Transport that affords
high reliability and security, as well as
segmentations from the providers Network
A spare Wavelength (Leased ) is used to
provide clear-channel transport to a customer
The Customers Bandwidth requirements arecleanly separated from the providers core
Network Needs.
New Applications with DWDM
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Thank You