Transcript No Slide Title

INTRODUCTION
TO DWDM
18-Jul-15
ALTTC/TX-I/DWDM
1
CONTENTS
•
•
•
•
•
•
•
The need for DWDDM
– Fibre exhaust- alternatives
The challenge:
– Tapping the unlimited fibre bandwidth
– Achieving the networking functions in the optical domain
Wdm approach to fibre exhaust
– Wdm functional block schematic
– Differences from conventional system: the amplifier
– Dwdm systems at present
Optical amplifiers
Dwdm components
Optical bands
– Standard wavelengths: ITU grid
Dwdm applications :
– Benefit to operators
– New issues before planners
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FIBRE EXHAUST
2.5- Gbit/s
2.5- Gbit/s
2.5- Gbit/s
2.5- Gbit/s
transmitter
10-Gbit/s
transmitter
2.5-Gbit/s
2.5 Gbit/s
2.5 Gbit/s
reciever
10-Gbit/s
regenerator
10-Gbit/s
reciever
INSTAL HIGHER BITRATE TDM
EXPENSIVE, NEW FIBRE NEEDED
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FIBRE EXHAUST
10-Gbit/s
transmitter
10-Gbit/s
regenerator
10-Gbit/s
reciever
2.5- Gbit/s
2.5- Gbit/s
2.5- Gbit/s
2.5- Gbit/s
transmitter
2.5-Gbitt/s
transmitter
2.5-Gbitt/s
transmitter
2.5-Gbitt/s
transmitter
2.5-Gbitt/s
transmitter
18-Jul-15
2.5-Gbit/s
2.5Gbit/s
2.5
Gbit/s
2.5 Gbit/s
reciever
λ1
λ1
λ2
λ3
M
U
X
λ4
DEPLOY DWDM
ALTTC/TX-I/DWDM
D
E
M
U
X
λ2
2.5- Gbit/s
reciever
λ3
2.5- Gbit/s
reciever
λ4
2.5- Gbit/s
reciever
2.5- Gbit/s
reciever
4
EVOLUTION OF DWDM
Late
1990’s
Mid
1990’s
Early
1990’s
Late
1980’s
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64-160 channels
25-50 GHZ spacing
16-40 channels 100-200 GHz spacing
Dense WDM, integrated systems with
Network Management, add-drop functions.
2-8 channels passive
WDM 200-400 GHz spacing
WDM components/parts
2 channels Wideband
WDM 1310 nm, 1550 nm
ALTTC/TX-I/DWDM
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ACHIEVING HIGHER BANDWIDTH
THREE POSSIBLE SOLUTIONS
• INSTAL NEW FIBRE EXPENSIVE
• INVEST IN NEW TDM
TECHNOLOGIES TO
ACHIEVE HIGHER
BANDWIDTH.
VERY
EXPENSIVE
REQUIRE NEW
TYPE FIBRE
• DEPLOY DWDM
ECONOMICA
L
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THE CHALLENGE:Continuous growth in traffic…
Calls for tapping the unutilized bandwidth of the media
ACHIEVE NETWORKING FUNCTIONS (ROUTING etc) IN OPTICAL DOMAIN
JUST LIKE WIDENING OF ROAD USING AVAILAB.E LAND TO MEET INCREASED TRAFFIC
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DWDM BASICS
SINGLE FIBRE
SDH OPTICAL SIGNALS
NEW REQUIREMENTS:
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BLOCK SCHEMATIC
OPTICAL
SIGNALS.
STM-1
STM-4
STM-16
ATM
IP
Tx
1
2
.
.
.
.
16
MUX
W
D
M
DEMUX
OFA
Rx
W
D
M
TRANSPONDERS
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Wayside Optical Add/Drop Multiplexer
1
TM
TM
WDM
MUX
2
O
A
 15
WDM
DEMU
XO
A

16

1-4
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 5-8
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Optical Add/Drop Multiplexing
Terminal Equipt
In-Line Amplifier
1 2
2 2
Terminal Equipt
fixed OADM:
2
2 1
1 1
Configurable
OADM :
1 or 2
1 2
2 2
2 1
OADM : Optical Add/Drop Multiplexer
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OADM Connectivity
• Omnibus
29 express ch
32 ch
WDM
• From terminal to OADM, or from OADM to
OADM
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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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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
• Simpler Operations : Embedded DCC
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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
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DWDM Components
•
•
•
•
•
Transmit
Receive
Repeater
Add Drop
Distribution: Cross connects
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TP
OMUX
TP
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OA
OADM
ALTTC/TX-I/DWDM
OXC
ODEMUX
OPTICAL NETWORK ELEMENTS
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OPTIONAL
REGENERATOR
O/E
Electrical
REGENERATION
E/O
TRANSPONDER / TRANSLATOR /
WAVELENGTH CONVERTOR
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Optical Multiplexers & Filters
W\L FILTER
W\L
MULTIPLEXER
W\L ROUTER
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OPTICAL ADD DROP MUX
M
D
COUPLER
CIRCULATOR
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INPUT FIBRE
LINKS
OPTICAL CROSSCONNECT
SWITCH
MATRIX
TRIBUTARY LINKS
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T
T
T
T
T
T
T
T
WAVELENGTH
ADAPTATION
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OPTICAL AMPLIFIERS
Isolator
Coupler
Pump
laser
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Coupler
Erbium-doped
Fiber-(10-50 m)
ALTTC/TX-I/DWDM
Isolator
Pump
laser
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NMS FOR DWDM SYSTEMS
• NMS IN CONVENTIONAL SDH SYSTEMS:
– DCC: TIME SLOTS
• DWDM – NO 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)
Line Terminal Equipment
Tx 1
DATA IN
Tx 2
Tx 3
Tx 4
Tx 5
Tx 6
Tx 7
Tx 8
In-line Amplifier
Line Terminal Equipment
1
1
2
2
3
3
4
4
5
5
6
8
Tx sup
System Control
Processor
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Rx
Tx
OSC
ALTTC/TX-I/DWDM
Network Management
Rx
Rx
Rx
Rx
6
 + supervisory
7
Rx
Rx
7
Rx sup
Rx
8
Rx
System Control
Processor
Network Management
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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 spacing of 200, 100, 50 GHz for different
applications
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ITU-T BAND ALLOCATION
Optical
Supervisory
channel
C BAND
BLUE
BAND
1500
1520
1530
L BAND
RED
BAND
1542 1547
1560
1620
• C BAND 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.
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ITU –T G.692 Frequency Grid
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
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1539.77
193.4 ALTTC/TX-I/DWDM
1550.12
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LIMITATIONS
•
DWDM TRANSMISSION IS ANALOG.
THE IN LINE AMPLIFIERS ARE
ALSO ANALOG.
THIS IMPLIES THAT THE SIGNAL TO
NOISE RATIO WORSENS WITH
DISTANCE.
• TO KEEP THE BER WITHIN LIMITS,
THE SIGNALS ARE REQUIRED TO BE
3R PROCESSED IN ELECTRICAL
DOMAIN.
• FIBRE DISPERSION IS ANOTHER
LIMITATION.
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LIMITATIONS
• THE MAXIMUM DISTANCE IS 640 Kms
MADE OF 8 SPANS OF 80 Kms. THE
ASSUMPTIONS ARE:
* FIBRE ATT INCLUDING SPLICE
LOSS IS 0.28 dB/km
* SPAN LOSS OF 22 dB.
* TOTAL DISPERSION IS LESS
THAN 12800 ps/nm.
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New Applications with DWDM
• Long Distance
– Longer Regenerator spacing: Hundreds to
Thousands of Kilometers
– Saving of Regenerators
– Very Low Bandwidth Cost
– Scalability
– Very Fast Commissioning of Optical Paths: Within
a week as compared to several months/ year with
old technologies
– Advanced Networking Capabilities
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New Applications with DWDM
• Metropolitan Area Network
– Unlimited Bandwidth, bit rate and format
transparency
– Efficient Bandwidth use and Management
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New Applications with DWDM
• High speed parallel Data Transport
– Certain Computer Applications Require that
Computer Centers be interconnected with multiple
high speed channels that have capacity and
availability requirements, as well as interlink delay
restrictions that can not be met by TDM Transport
Systems.
– In General, DWDM Optical Transport Benefits all
Delay Sensitive Applications
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New Applications with DWDM
• Wavelength Leasing
– Network 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 Customer’s Bandwidth requirements are
cleanly separated from the providers core Network
Needs.
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Thank You
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