wdm basics
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All Rights Reserved © Alcatel-Lucent 2007Transmission Networks · WDM Technology - Fundamentals
1·1 Module 1WDM Transmission Basics
3JK10358AAAAWBZZA Edition 01
Section 1WDM Technology -
Fundamentals
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Objectives
Explain the reasons for deploying a WDM network.Describe the basic WDM technology and the
operational concepts.Describe the functions of the major components used
in WDM.
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1 Introduction
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1 Introduction
1.1 Network Hierarchy
Mesh
Ring
Inter-metroconnection
s
Inter-metroconnection
s
Inter-metroconnection
s
Point-to-point
Residential networks:
- DSL- Cable modem
SDH/SONET:
- POTS- Wireless
ISP POP:- IP services
Enterprise:- Frame Relay - ESCON- Fiber Channel- Gigabit
Ethernet
Long-haul
networks
Metro-politannetworks
Accessnetwork
s
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1 Introduction
1.2 Bandwidth Demand
Data
Voice
Voice-centric
Data-centric
Trafficvolume
50
100
150
200
250
1996 1997 1998 1999 2000 2001
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1 Introduction
1.3 Options for Increasing Carrier Bandwidth
Space Division Multiplexing (SDM) increasing the number of fibers
Time Division Multiplexing (TDM) increasing the bit rate
Wavelength Division Multiplexing (WDM) increasing the number of wavelengths
Complementarysolutions
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1.3.1 Time Division Multiplexing
Concept
Bits of information
Transmission link
TDM
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1.3.1 Time Division Multiplexing
SDH Standard
Incoming streams
Link rate =(2.5Gbps x 4 =
10Gbps)
Outgoing
stream
Bit rate = 2.5Gbps
(T)
(T)
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1.3.2 Wavelength Division Multiplexing
Concept
TRANSMITTERS
Separating
signals
Optical fiber
RECEIVERS
Combining
signals
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1.3.2 Wavelength Division Multiplexing
Input Format Independence
SDH
IP
Leased line
ATM
...
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1.3.3 TDM versus WDM
Network Evolution
16 x STM-1
16 x STM-1
N channels
Colored signals with specific wavelengths
16 x STM-1
16 x STM-1
N terminals
WDMSTM-16terminal
STM-16terminal
STM-16terminal
STM-16terminal
1R 1R 1R 1R
N terminals
16 x STM-1
3R 3R 3R
REGENERATOR REGENERATOR REGENERATOR
16 x STM-1
16 x STM-1
16 x STM-1
16 x STM-116 x STM-1
16 x STM-1
16 x STM-1
16 x STM-1
16 x STM-1
16 x STM-1
16 x STM-116 x STM-1
16 x STM-1
16 x STM-1
16 x STM-1
16 x STM-116 x STM-1
16 x STM-1
16 x STM-1
16 x STM-116 x STM-1
16 x STM-1
16 x STM-1
16 x STM-1
16 x STM-1
16 x STM-1
16 x STM-116 x STM-1
16 x STM-1
16 x STM-1
16 x STM-1
STM-16terminal
STM-16terminal
N terminals
N terminals
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1.3.3 TDM versus WDM
Unlimited Transmission Capacity
WDM + TDM
Year
N x 2.5Gbps
TDMSingle Channel
128 x 2.5Gbps
64 x 2.5Gbps
32 x 2.5Gbps
16 x 25Gbps
8 x 25Gbps
4 x 25Gbps
2 x 25Gbps
8 x 10Gbps
16 x 10Gbps
40 x 10Gbps
N x 10Gbps
200Gbps
100Gbps
10Gbps
140Mbps
565Mbps
2.5Gbps
10Gbps
40Gbps
Global capacity
per fiber (Gbps)
0.1
1
10
100
1000
1984
1986
1988
1990
1992
1994
1996
1998
2000
2001
2004
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2 Varieties of WDM
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2 Varieties of WDM
2.1 WDM Evolution
64 channels50GHz spacing
64 channels 100-200GHz spacingDense WDM, integrated systems with network management, add-drop functions
2-8 channelsNarrowband WDM 200-400Ghz spacing Passive WDM components
2 channels Wideband WDM 1310nm, 1550nm
Evolution of WDM
Late1990’s
1996
Early1990’s
1980’s
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2 Varieties of WDM
2.2 Conventional WDM Definition
Transmit
Receive
End system End system
End system End system
(1310nm + 1550nm)
(1310nm + 1550nm)
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2.3 DWDM Definition
Absorption Spectrum of the Optical Fiber
Wavelength (nm)
Loss (dB/km
)
800 1000 1200 1400 1600 1800
1
0.5
10
5
S C L
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2.3 DWDM Definition
C Band
BLUE BAND RED BAND
1528nm 1546nm 1564nm
C Band
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2.3 DWDM Definition
ITU-T Standard for 100GHz Spacing in C Band
Nominal Frequencies Allocation Plan (Red Band)
Channel Central Central frequency (THz) number wavelength (nm)
20 1561.42 192.000
21 1560.61 192.100
22 1559.79 192.200
23 1558.98 192.300
25 1557.36 192.500
26 1556.55 192.600
27 1555.75 192.700
28 1554.94 192.800
30 1553.33 193.000
31 1552.52 193.100
32 1551.72 193.200
33 1550.92 193.300
35 1549.32 193.500
36 1548.51 193.600
37 1547.72 193.700
38 1546.92 193.800
Nominal Frequencies Allocation Plan (Blue Band)
Channel Central Central frequency (THz) number wavelength (nm)
42 1543.73 194.200
43 1542.94 194.300
44 1542.14 194.400
45 1541.35 194.500
47 1539.77 194.700
48 1538.98 194.800
49 1538.19 194.900
50 1537.40 195.000
52 1535.82 195.200
53 1535.04 195.300
54 1534.25 195.400
55 1533.47 195.500
57 1531.90 195.700
58 1531.12 195.800
59 1530.33 195.900
60 1529.55 196.000
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2 Varieties of WDM
2.4 CWDM Definition
ChannelWaveleng
thFrequen
cyChann
elWavelengt
hFrequen
cy
1 1470nm203.94TH
z5 1550nm
193.41THz
2 1490nm201.20TH
z6 1570nm
190.95THz
3 1510nm198.54TH
z7 1590nm
188.55THz
4 1530nm195.94TH
z8 1610nm
186.21THz
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3 DWDM Basic Components
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3 DWDM Basic Components
3.1 DWDM Network
Post-amplifier
Pre-amplifier
In-line amplifiers
Transponderinterfaces
Directconnection
s
Terminal A Terminal B
Transponderinterfaces
Directconnection
s
… …
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3 DWDM Basic Components
3.2 Transponder
StandardReceiver
Client Interface
DWDM Interface
3RRegenerati
on
ColoredInterface
B&WInterface
3RRegenerati
on
OptimizedReceiver
OpticalSignal
OpticalSignal
ElectricalSignal
ElectricalSignal
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3 DWDM Basic Components
3.3 Multiplexer/Demultiplexer
Multiplexing and demultiplexing in a bidirectional communication
Optical fiber
Optical fiber
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3.4 Optical Amplifier
Applications
Post-amplifier
In-line Amplifier
Pre-amplifier
TRANSMITTER
RECEIVER
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3.4 Optical Amplifier
Types
RFA
TDFA
EDFA
GS-TDFA
EDTFA
GS-EDFA
L BandC Band
1575
162015601530
S BandS+ Band
14801420Waveleng
th(nm)
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3.4 Optical Amplifier
Erbium-Doped Fiber Amplifier
Active fiber doped with Erbium ions
Ground state
Excited state
Energy supply(pumping)
Spontaneousemission
Stimulatedemission
electron
Noisegenerati
on
Opticalamplification
photon Signal in
Signal in Signal outPump
coupler
Pumplaser diode
ERBIUM-DOPEDFIBER AMPLIFIER
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3.4 Optical Amplifier
Raman Amplification Principle
(nm)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
1450 1470 1490 1510 1530 1550 1570 1590 1610 1630 1650
@1455nm @1480nm
Gain spectrumversus pump wavelength
Gain(relative)
(gain)=(pump)+100nm
Transmitter Receiver
1455nm pump
Optical fiber
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3 DWDM Basic Components
3.5 OADM Concept
Optical fiber
1 , 2 , … , n
- n
AmplifierOptical fiber
OADM
n n
Amplifier
1 , 2 , … , n
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4 Module Evaluation
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Answer the Questions (1/8)
Is the following statement true or false?WDM systems cost more than installing more fibers.
Select the correct answer.
True
False
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Answer the Questions (2/8)
What is the multiplexing concept used for SDH?
Select the correct answer.
TDM
SDM
WDM
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Answer the Questions (3/8)
Is the following statement true or false?WDM systems are input format independent.
Select the correct answer.
True
False
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Answer the Questions (4/8)
Which band is in the third optical window?
Select the correct answer.
A
C
B
S
L
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Answer the Questions (5/8)
Associate each wavelength spacing to the correct multiplexing technology.To do this, draw a line between each wavelength spacing from the list on the left and the appropriate technology from the list on the right.
100GHz
50GHz
3000GHz
DWDM
WDM
400GHz
CWDM
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Answer the Questions (6/8)
Fill in the blanks in the figure below to situate each element that makes up a DWDM network.
The elements are: MUX (multiplexer) PreA (pre-amplifier) ILA (In-line amplifier) Receiver
Transmitter DEMUX (demultiplexer) PostA (post-amplifier)
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Answer the Questions (7/8)
Is the following statement true or false?The main function of the transponder is to convert theB&W wavelength to a colored wavelength.
Select the correct answer.
True
False
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Answer the Questions (8/8)
What is the amplification range for an EDFA?
Select the correct answer.
1530-1610nm
1490-1530nm
1530-1565nm
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Summary (1/2)
Options for increasing carrier bandwidth:Space Division Multiplexing (SDM)Time Division Multiplexing (TDM)Wavelength Division Multiplexing (WDM)
Varieties of WDM:Conventional WDM:
2 wavelengths: 1310nm and 1550nm Or 400 GHz spacing around 1550nm
Dense WDM (DWDM): Range: 1460nm-1565nm S, C, L bands Spacing: 200, 100, 50, 25GHz
Coarse WDM (CWDM): Range: 1270nm-1610nm Spacing: 3000GHz
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Summary (2/2)
A DWDM network is made up of:a transmitter, also called transmit transponder,a multiplexer and a demultiplexer,amplifiers:
a post-amplifier, also called booster, In-Line Amplifiers (ILAs), also called repeaters, a pre-amplifier,
an optical fiber,an Optical Add-Drop Multiplexer (OADM) which is optional,a receiver, also called receive transponder.
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Self-Assessment on the Objectives
Please be reminded to fill in the formSelf-Assessment on the Objectivesfor this module
The form can be found in the first partof this course documentation
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End of ModuleWDM Transmission Basics