DWDM Tutorial
DWDM Tutorial
DWDM Tutorial
Division Multiplexing
DWDM Primer
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directly to those companies
This document and its contents are provided by Fujitsu Network Communications, Inc. (FNC) for guidance purposes only. This document is provided
“as is” with no warranties or representations whatsoever, either express or implied, including without limitation the implied warranties of
merchantability and fitness for purpose. FNC does not warrant or represent that the contents of this document are error free.
Furthermore, the contents of this document are subject to update and change at any time without notice by FNC, since FNC reserves the right,
without notice, to make changes in equipment design or components as progress in engineering methods may warrant. No part of the contents of
this document may be copied, modified, or otherwise reproduced without the express written consent of FNC.
Figure 1-1: Support Organizations........................................... 1-4 Figure 6-1: FLASHWAVE 7420 .............................................. 6-4
Figure 1-2: FOCIS ................................................................... 1-6 Figure 6-2: FLASHWAVE 7420 Ring ...................................... 6-6
Figure 2-1: Discrete Channels ................................................. 2-4 Figure 6-3: FLASHWAVE 7500 .............................................. 6-8
Figure 2-2: DWDM Transport .................................................. 2-6 Figure 6-4: Multiservice Operations Applications.................. 6-10
Figure 2-3: Wavelength ........................................................... 2-8 Figure 6-5: MSO Network Solution ....................................... 6-12
Figure 3-1: Time Division Multiplexing..................................... 3-4
Figure 3-2: Wavelength Division Multiplexing.......................... 3-6
Figure 3-3: WDM Filters........................................................... 3-8
Figure 4-1: Optical Network Drawing....................................... 4-4
Figure 4-2: Tunable Laser ....................................................... 4-6
Figure 4-3: Laser Signal Sources ............................................ 4-8
Figure 4-4: Regeneration....................................................... 4-10
Figure 4-5: Network Regeneration......................................... 4-12
Figure 4-6: EDFA Model ........................................................ 4-14
Figure 4-7: Erbuim-Doped Fiber Amplifier ............................. 4-16
Figure 4-8: Fiber Bands and Amplifiers ................................. 4-18
Figure 4-9: Distributed Raman Amplifiers.............................. 4-20
Figure 5-1: Optical Network Spectrum..................................... 5-4
Figure 5-2: Signal Bandwidth................................................... 5-6
Figure 5-3: Eye Pattern vs. Data Stream................................. 5-8
Figure 5-4: Eye Pattern Display............................................. 5-10
Figure 5-5: Forward Error Correction..................................... 5-12
Figure 5-6: OOB-FEC Example ............................................ 5-14
Figure 5-7: OSNR .................................................................. 5-16
Figure 5-8: Fiber Attenuation ................................................. 5-18
Figure 5-9: Fiber Signal Loss in S-Band, C-Band, and L-Band . 5-
20
Figure 5-10: Power Levels..................................................... 5-22
Figure 5-11: Dispersion and WDM ........................................ 5-24
Figure 5-12: Chromatic Dispersion ........................................ 5-26
Figure 5-13: Compensation Modules..................................... 5-28
Figure 5-14: Chirp.................................................................. 5-30
Figure 5-15: Polarization Mode Dispersion............................ 5-32
Figure 5-16: PMD Compensation .......................................... 5-34
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List of Tables DWDM Primer
Course Description
Course Description DWDM Primer
Course Description
Name Objectives
Dense Wavelength Division Multiplexing Primer After completing this course, the student should be able to:
• Identify DWDM optical network elements
Purpose
• Describe DWDM characteristics
The purpose of the DWDM Primer course is to provide an
introduction to dense wavelength division multiplexing (DWDM). • Identify DWDM optical network considerations
Additionally, this course will discuss why DWDM is an important
• Identify Fujitsu Network Communications, Inc. (FNC)
innovation in optical networks and the benefits it can provide.
products that offer network solutions
Prerequisite
While there are no formal prerequisites for this course, the
following make the course more meaningful, as an in-depth
analysis of these subjects is beyond the scope of DWDM Primer
course:
• SONET knowledge and experience
• Ethernet knowledge and experience
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DWDM Primer Course Description
Scope
The DWDM Primer course is intended for network planners, and Reference Documents
engineers who would like to familiarize themselves with DWDM
technology. In addition, other personnel who wish to gain a The following documents were used to develop this course:
general understanding of DWDM are encouraged to attend. • FNC-742-0031-120, System Description and
This student guide is intended as a tool for classroom use only. Engineering (FLASHWAVE 7420)
Students interested in training on other aspects of FNC • FNC-591-0013-120, System Description and
Engineering (FLASHWAVE 7500)
equipment and capabilities should investigate other courses
offered by FNC, such as applicable turn-up & testing, • TRN-7500-TM-013, FLASHWAVE 7500 Turn-Up and
maintenance, and engineering courses. Test
• TRN-7420-TM-031, FLASHWAVE 7420 Turn-Up and
Test
• PMB-03-031 FLASHWAVE 7500 Product Management
Bulletin (Release 1.3 Announcement)
• PMB-03-004 FLASHWAVE 7420 Product Management
Bulletin (New Product Announcement)
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Course Description DWDM Primer
Educational Services
Richardson, Texas
Register for class
800-777-3278 ext. 4961
fax: 972-479-7117
e-mail ed.svcs@fnc.fujitsu.com
Sales
Richardson, Texas/Regional Offices
800-777-FAST
(800-777-3278)
Technical Publications
Richardson, Texas
800-777-FAST
(800-777-3278)
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DWDM Primer Course Description
Support Organizations
FNC support organizations (see Figure 1-1) include: • Sales (Richardson, Texas and regional offices)—
Provides sales assistance for all FNC products.
• Educational Services—Provides training on all FNC
products. Classes are conducted at Richardson, Texas
Call 800-777-FAST (800-777-3278) for information
as well as at customers’ locations.
regarding:
• Technical Assistance (Richardson, Texas)—Answers
- Upgrades
questions regarding FNC products. Service is provided
via telephone. - Replacement Parts
- Ordering Information
Call 800-USE-FTAC (800-873-3822) for questions
regarding: - Local Sales Offices
- Technical Performance - Product Descriptions
- Equipment Specifications - Documentation
Note: FTAC stands for Fujitsu Technical Assistance Note: FAST stands for Fujitsu Assistance.
Center. • Technical Publications (Richardson, Texas)
• Repair and Return (Richardson, Texas)—Provides
Additional information regarding FNC and any of the support
repair services for all FNC products.
organizations can be located at our Web site:
Call 800-525-0303 http://us.fujitsu.com/services/telecom
Note: Online documentation is available to FNC
Fujitsu Network Communications, Inc.
customers on the FNC Web site by accessing
2791 Telecom Parkway
Partners and FOCIS:
Richardson, Texas 75082-9983
https://partners.fnc.fujitsu.com
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Course Description DWDM Primer
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DWDM Primer Course Description
FOCIS
FOCIS is a Web based, customer accessible repository of Fujitsu
technical documentation such as:
• Product change notices
• Information bulletins
• Manufacturer discontinued notices
• Manuals
• Software downloads and links
• Training information
• Document downloads
In addition, FOCIS has information on Technical Assistance
Center (TAC) contacts, links to technical training courses and
FLEXR registration.
• Access the FNC Web site at
https://partners.fnc.fujitsu.com
• Select Logon to FOCIS
Note: If you know your user name and password, log
on. If not, go to the registration link and request
a logon. Wait one business day for verification
of access.
• The Partners page is displayed (see Figure 1-2).
• Select FOCIS.
• Select Services—Various FNC services are listed for
query.
Reference Documentation: Not applicable
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Course Description DWDM Primer
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Lesson 2
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DWDM Primer DWDM Primer Overview
Purpose
This lesson provides an overview of dense wavelength division
multiplexing (DWDM).
Objectives
Upon completion of this lesson, the student should be able to:
• Define DWDM
• Recognize the advantage that DWDM has over time
division multiplexing (TDM)
• Define a wavelength
Reference Documents
The following documents were used in the development of this
lesson:
• TRN-7500-TM-013, FLASHWAVE 7500 Turn-Up and
Test
• TRN-7420-TM-031, FLASHWAVE 7420 Turn-Up and
Test
• PMB-03-031 FLASHWAVE 7500 Product Management
Bulletin (Release 1.3 Announcement)
• PMB-03-004 FLASHWAVE 7420 Product Management
Bulletin (New Product Announcement)
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DWDM Primer Overview DWDM Primer
9X 9X
SONET SONET
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DWDM Primer DWDM Primer Overview
Why DWDM?
Dense wavelength division multiplexing permits rapid network
deployment and significant network cost reduction. Use of
DWDM allows deployment of less fiber and hardware with more
bandwidth being available relative to standard SONET networks.
DWDM Definition
Dense wavelength division multiplexing is a fiber optic
transmission technique that employs light wavelengths to
transmit data (refer to “What is a Wavelength?” on page 9).
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DWDM Primer Overview DWDM Primer
9X 9X
SONET
DWDM
SONET
DWDM
ILA ILA ILA
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DWDM Primer DWDM Primer Overview
Dense wavelength division multiplexing systems allow many Multiservice traffic of all types can now be carried over the
discrete transport channels to be carried over a single fiber pair. DWDM infrastructure shown in Figure 2-2. Thereby enabling
Nine discrete channels share the fiber pair with an aggregate faster speed to market of multiservice traffic offerings at a lower
bandwidth of 90 Gb/s in Figure 2-2. cost for new services to be transported over the DWDM system.
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DWDM Primer Overview DWDM Primer
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DWDM Primer DWDM Primer Overview
What is a Wavelength?
A wavelength is the distance between the crests of a wave (Figure
2-3). The higher the frequency, the shorter the wavelength.
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DWDM Primer Overview DWDM Primer
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Lesson 3
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DWDM Primer Wavelength Division Multiplexing
Purpose
This lesson provides an overview of wavelength division
multiplexing (WDM). Since DWDM systems are derived from
wavelength division multiplexing (WDM) systems, WDM will be
discussed and the relationship between WDM and DWDM
systems will be examined.
Objectives
Upon completion of this lesson, the student should be able to:
• Understand basic WDM theory and operational
concepts
• Describe the different WDM types
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Wavelength Division Multiplexing DWDM Primer
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DWDM Primer Wavelength Division Multiplexing
Types of Multiplexing
Multiplexing is sending multiple signals or streams of information
through a circuit at the same time in the form of a single, complex
signal and then recovering the separate signals at the receiving
end. Basic types of multiplexing include frequency division
multiplexing (FDM), time division multiplexing (TDM), and
wavelength division multiplexing (WDM), with TDM and WDM
being widely utilized by telephone and data service providers
over optical circuits.
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Wavelength Division Multiplexing DWDM Primer
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DWDM Primer Wavelength Division Multiplexing
Varieties of WDM
Early WDM systems transported two or four wavelengths that
were widely spaced. WDM and the follow-on technologies of
coarse wavelength division multiplexing (CWDM) and dense
wavelength division multiplexing (DWDM) have evolved well
beyond this early limitation.
WDM
Traditional, passive WDM systems are wide-spread with 2, 4, 8,
12, and 16 channel counts being the normal deployments. This
technique usually has a distance limitation of under 100
kilometers.
CWDM
Today, CWDM typically uses 20-nm spacing (3000 GHz) of up to
18 channels. The CWDM Recommendation ITU-T G.694.2
provides a grid of wavelengths for target distances up to about
50 kilometers on single mode fibers as specified in ITU-T
Recommendations G.652, G.653 and G.655. The CWDM grid is
made up of 18 wavelengths defined within the range 1270 nm to
1610 nm spaced by 20 nm.
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Wavelength Division Multiplexing DWDM Primer
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DWDM Primer Wavelength Division Multiplexing
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Wavelength Division Multiplexing DWDM Primer
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Lesson 4
Optical Networks
Optical Networks DWDM Primer
Purpose
This lesson provides an overview of optical networks and the
components that make up an optical network.
Objectives
Upon completion of this lesson, the student should be able to:
• Identify the components of an optical network
• Describe functions of the major components that make
up an optical network
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Optical Networks DWDM Primer
Optical Network
Figure 4-1 shows the five main components of a DWDM optical 5. Receiver (receive transponder):
network. The components of a DWDM optical network are: - Changes optical pulses back to electrical bits
1. Transmitter (transmit transponder): - Uses wideband laser to provide the optical pulse
- Changes electrical bits to optical pulses
- Is frequency specific
- Uses a narrowband laser to generate the optical
pulse
2. Multiplexer/demultiplexer:
- Combines/separates discrete wavelengths
3. Amplifier:
- Preamplifier boosts signal pulses at the receive
side
- Postamplifier boosts signal pulses at the transmit
side (postamplifier) and on the receive side
(preamplifier)
- In line amplifiers (ILA) are placed at different
distances from the source to provide recovery of
the signal before it is degraded by loss.
4. Optical fiber (media):
- Transmission media to carry optical pulses
- Many different kinds of fiber are used
- Often deployed in sheaths of 144–256 fibers
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Optical Networks DWDM Primer
O/4-Shift DFB
S-Bends
Laser Array
Combiner
Tunable Laser
Figure 4-2 shows one method of transmission, the tunable laser.
Multiple individual lasers, eight in this example, are built into one
piece of silicon. One selected laser is turned on and temperature
tuned to the exact desired wavelength. A waveguide feeds the
signal combiner that sums the input 1310 nm wavelength with
the desired laser wavelength and then routes the signal from the
laser to the silicon optical amplifier (SOA) that boosts the signal
output. Configuration is controlled by the operating system
software in use for the DWDM system.
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Optical Networks DWDM Primer
Backplane
Signals High Speed
Electrical
Driver
Laser
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Optical Networks DWDM Primer
Original Signal
1R, Amplification
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Optical Networks DWDM Primer
Asynchronous Transponder
2R Electrical
No Timing So Not Bit Rate Optical Amplifier
Dependant 1R Optical
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Optical Networks DWDM Primer
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Optical Networks DWDM Primer
1480 nm
Pump
Laser Optical Cable
OC-48 Mixer
1551 nm OC-48
1551 nm
Erbium-Doped
Fiber Amplifier
SONET
Network (EDFA)
Element
EDFA Amplifier
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Optical Networks DWDM Primer
Fiber Bands
Three optical frequency bands are used today for fiber-optic
DWDM networks. Figure 4-8 highlights C-band and L-band,
which are considered the most useful. The bands are:
• C-band (conventional) has a range from 1530 nm to
1570 nm (most commonly used band in DWDM).
• L-band (long wavelength) has a range from 1570 to
1625 nm.
• S-band (short wavelength) has a range from 1450 to
1500 nm.
Amplifier Requirements
Different C-band and L-band amplifiers are required because
EDFA must be optimized for either C-band or L-band
amplification. The following applies:
• High pump power with short EDFA fiber is used for
C-band amplifiers.
• Medium pump power with long EDFA fiber is used for
L-band amplifiers.
• Thulium-doped fluoride-based fiber amplifier (TDFA)
for 1450–1490 nm S-band is used in conjunction with
Raman fiber amplifiers (RFA). The S-band has only
recently come into DWDM system design.
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Optical Networks DWDM Primer
Distributed Amplification In
Transmission Fibers
Simulation
Channel 32
Pump
Raman Amplifiers
Raman amplifiers (fiber amplifiers) are devices that amplifies an
optical signal directly, without first converting the signal to an
electrical signal, amplifying the signal electronically, and then
reconverting it to an optical signal. Characteristics of Raman
amplification include:
• Silicon fiber used as the gain mechanism
• Not as efficient as erbium; however, the lower
efficiency is compensated for by the higher linear
density of silicon in the fiber
• Amplifies over C-band, L-band, and S-band
Distributed Raman
Raman amplifiers, as shown in Figure 4-9, are coming into
general use to accomplish operation over longer spans with
fewer regeneration sites.
Raman amplification allows the transmission fiber to be used as
an amplifier, resulting in the following benefits:
• Reduced effective span loss
• OSNR improvement
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Optical Networks DWDM Primer
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DWDM Primer Optical Network Considerations
Purpose
This lesson provides an overview of considerations that must be
taken into account when designing an optical network.
Objectives
Upon completion of this lesson, the student should be able to:
• Identify the bandwidth range used in DWDM
• Identify common impairments to DWDM transmissions
• Describe how forward error correction (FEC) is a
solution for bit error rate (BER)
• Identify the types of dispersion
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Optical Network Considerations DWDM Primer
X-Rays
Ultraviolet
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DWDM Primer Optical Network Considerations
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Optical Network Considerations DWDM Primer
Filter Width
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DWDM Primer Optical Network Considerations
ITU-T Grid
The International Telecommunication Union (ITU)
Telecommunication Standardization Sector (ITU-T) established a
set of standards for telecommunications that drives all optical
DWDM systems today.
Systems are based on an absolute reference to 193.10 THz that
corresponds to a wavelength 1552.52 nm with individual
wavelengths spaced in steps of 50 GHz or a wavelength step of
0.41 nm from the reference. All land-based DWDM systems
follow this standard.
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Optical Network Considerations DWDM Primer
Eye Pattern
Equivalent
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DWDM Primer Optical Network Considerations
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Optical Network Considerations DWDM Primer
Valid Range
1s Are Above Threshold
Decision Threshold
Valid Range
0s Are Below Threshold
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DWDM Primer Optical Network Considerations
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Optical Network Considerations DWDM Primer
Codes
Original Lossy Find + Correct Errors Original
Signal Transmission Signal
Media Errors
Generated
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DWDM Primer Optical Network Considerations
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Optical Network Considerations DWDM Primer
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DWDM Primer Optical Network Considerations
Out-of-Band FEC
Out-of-band forward error correction (OOB-FEC) is the type used
for DWDM systems. FEC bytes are added on top of the signal to
be carried (Figure 5-6). For example, adding OOB-FEC changes
the signal from 9.958 Gb/s to 10.7 Gb/s for 10 Gb/s SONET
transport, resulting in 6 percent overhead added outside the
normal signal envelope. The effect of approximately 6-dB optical
system gain, depending on OSNR and other impairments on the
DWDM route, can be achieved. The 6-dB gain is not an actual
power gain, but an improvement in the OSNR. It permits greater
distance between ILA sites on the optical span.
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Optical Network Considerations DWDM Primer
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DWDM Primer Optical Network Considerations
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Optical Network Considerations DWDM Primer
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DWDM Primer Optical Network Considerations
Fiber Attenuation
All transmission fiber suffers from the losses brought about by
attenuation, as shown in Figure 5-8. The characteristics of the
common fibers have the following in common:
• The 1550-nm window has the lowest attenuation.
• The large spike is due to absorption by water
molecules. This problem has been greatly reduced on
fibers manufactured today, allowing almost optimum
minimum attenuation.
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Optical Network Considerations DWDM Primer
0 .3 0
Loss (dB/km) 0 .2 8
1460nm
0 .2 6
0 .2 4
0 .2 2 1550nm
0 .2 0
0 .1 8
S C L
1450 1500 1550 1600
W a v e le n g th (n m )
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DWDM Primer Optical Network Considerations
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Optical Network Considerations DWDM Primer
Photon Limit
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DWDM Primer Optical Network Considerations
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Optical Network Considerations DWDM Primer
20
TeraLight
15
Dispersion (ps/nm/km)
LEAF
10
Wavelength (nm)
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DWDM Primer Optical Network Considerations
Fiber Dispersion
There are two kinds of dispersion, the most common is called
chromatic dispersion and is routinely compensated for by DWDM
systems for proper operation. The effects of polarization mode
dispersion (PMD) are much more insidious and difficult to make
compensation for in deployed networks.
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Optical Network Considerations DWDM Primer
Dispersion Values
25
Dispersion (psec/nm/km)
20
Erbium Window
15
10
-5
-10
-15
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DWDM Primer Optical Network Considerations
Chromatic Dispersion
Chromatic dispersion is a measure of fiber delay for different
wavelengths. Different wavelengths travel at different velocities
through fiber. The difference in velocity is called delay or
chromatic dispersion of the signal. Figure 5-12 illustrates the
common fiber type delay profiles. The erbium window represents
the minimum slope of chromatic dispersion.
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Optical Network Considerations DWDM Primer
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DWDM Primer Optical Network Considerations
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Optical Network Considerations DWDM Primer
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DWDM Primer Optical Network Considerations
Chirp
Chirp is an abrupt change of the center wavelength of a laser,
caused by laser instability. When the modulator pulses the laser,
a difference in the refractive index of the laser output occurs that
can cause chirp in a DWDM system. Chirp is the phenomenon of
the rising edge of a pulse having a slightly different frequency
than the falling edge (shown in Figure 5-14). It is a common
effect in devices that generate optical pulses (optical
modulators). Additionally, chirp interacts with fiber dispersion
potentially providing more or less dispersion tolerance.
Chirp usually occurs with a value of +1 GHz to –1 GHz. Each
laser transmits coherent light at a different center frequency for
each λ . Chirp can be provisioned to match the system input
requirements on many DWDM systems. On systems that allow
changes, the technician may adjust the chirp value to support the
network requirement, commonly the technician can only report
the presence and degree of chirp.
Chromatic dispersion near the tolerance limit for DWDM
receivers may be worse due to the chirp effect, and may require
dispersion compensation or closer spacing of ILA systems.
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Optical Network Considerations DWDM Primer
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DWDM Primer Optical Network Considerations
Polarization Mode Dispersion Polarization mode dispersion became an issue in the early
1980s. Manufacturing methods were improved and now fibers
Polarization is used to describe the orientation of a lightwave
can be manufactured that have low PMD. The PMD standard,
around its axis of propagation (Figure 5-15).
Standard Reference Materials (SRM) 2518, published by the
Polarization mode dispersion (PMD) describes the variation in National Institute of Standards and Technology (NIST), states 0.5
velocity of light waves as a result of traveling different ps of PMD per the square root of the fiber length in kilometers as
polarization paths. the proven PMD management interface, that is:
As light is refracted within the fiber, slight changes in the 0.5 ps/km–1/2
polarization of the light may occur. Light which takes different
The new fiber types have less than 0.5 PMD. For example,
paths within the fiber will have polarization differences resulting
10-Gb/s signals with 10 ps of PMD tolerance, derived from the
in dispersion.
formula above, would exhibit a range of about 400 kilometers; 40
Gb/s with 2.5 ps tolerance has an effective range of 25
kilometers (PMD compensation required). Research is underway
PMD Effect
to make even lower PMD fibers. New LEAF fiber, with 0.1 ps/
Although known, polarization mode dispersion (PMD) was not kilometers, allows distances of up to 10,000 kilometers of 10 Gb/
considered in early fiber manufacturing because of the limited s or 625 kilometers of 40 Gb/s.
impairments that PMD represented at the lower data rates
prevalent at that time. Later, as faster data transmission rates
became practical, various manufacturers began to provide fibers
that helped manage the PMD effects, for example:
• Low PMD fibers produced by outside vapor deposition
method (Corning).
• High PMD fibers produced by inside vapor deposition
method (Lucent).
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Optical Network Considerations DWDM Primer
PMDC
Receiver
Tolerance
At 10 Bb/s
Tolerance: 12 ps Average
Dispersion Compensator: 33 ps Average
Accumulation
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DWDM Primer Optical Network Considerations
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Optical Network Considerations DWDM Primer
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Lesson 6
6-2 FNC and FNC Customer Use Only May 21, 2004
DWDM Primer DWDM Network Solutions
Purpose
This lesson provides an introductory overview of two Fujitsu
products that provide DWDM solutions for Metro congestion and
fiber strain.
Reference Documents
The following documents were used in the development of this
lesson:
• TRN-7500-TM-013, FLASHWAVE 7500 Turn-Up and
Test
• TRN-7420-TM-031, FLASHWAVE 7420 Turn-Up and
Test
• PMB-03-031 FLASHWAVE 7500 Product Management
Bulletin (Release 1.3 Announcement)
• PMB-03-004 FLASHWAVE 7420 Product Management
Bulletin (New Product Announcement)
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DWDM Network Solutions DWDM Primer
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DWDM Primer DWDM Network Solutions
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DWDM Network Solutions DWDM Primer
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DWDM Primer DWDM Network Solutions
Applications
While the FLASHWAVE 7420 is ideally suited as an access
transport for metro core equipment because of its application
driven interface types, it is versatile enough to serve as a metro
core in small cities. An example of its versatility is illustrated in
Figure 6-2.
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r0323.fh10_1
r0322.fh10_1
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FLASHWAVE 7500: The Metro Core The FLASHWAVE 7500 is a reconfigurable OADM that at every
site customers can add and drop any traffic as needed to meet
Solution current or future bandwidth requirements, leaving no stranded
bandwidth.
The all-optical FLASHWAVE 7500 DWDM system (Figure 6-3)
provides a Reconfigurable Optical Add Drop Multiplexer The system consists of an Optical Add/Drop Multiplexer (OADM)
(ROADM) core for use in metropolitan and Inter-Office Facility or core shelf, which houses the management units of the system,
(IOF) networks. This next-generation ROADM platform is and the Optical Line Card (OLC) or tributary shelves for service
optimized for high capacity and evolving metro core networks. A offering units. Each OLC shelf can support up to a maximum of
variety of network configurations and traffic patterns are sixteen Low Speed OLC units or eight High Speed OLC units or
supported, including point-to-point, ring, and mesh network a mixture of both. Up to ten OLC shelves can be managed with
architectures. The FLASHWAVE 7500 offers 400 Gb/s of one OADM shelf. An optional Lambda Access Shelf (LAS) is
bandwidth that is scalable per wavelength. available for ease of fiber management between switch fabric
and OLC units.
System Description
Topologies
The FLASHWAVE 7500 platform is a next-generation wavelength
system that significantly drives down the cost of delivering Signal transport is available in the following topologies:
wavelength services. The FLASHWAVE 7500 platform supports • Point-to-point
all metro applications with up to 10 nodes in a 400-km ring. The
FLASHWAVE 7500 network only needs to be engineered once. • Linear add/drop (open ring)
Any wavelength can be added/dropped between any two nodes • OUPSR
without manual attenuation adjustments, banding restrictions or
reengineering. All traffic patterns hubbed, distributed and • Mesh network architectures
meshed are supported without stranding bandwidth in pre-
planned bands.
Multi-rate line cards provide bit rate and protocol independence
and deliver full interoperability with:
• SONET
• Next generation MSPP
• Gigabit Ethernet (100 megabit to 10 gigabit)
• Fiber Channel services
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Satellite Feeds
Local Feeds
HUB HUB
Headend HUB
Master Headend
HUB
VOD Servers
Studio/Tape
Data Secondary Secondary
Voice Hub Hub
Secondary
Hub
Telephony
HDT TR-303
DS1s
Taps
Digital Digital Video
Video DVB-ASI, DV6000, GbE
Drops
Cable Modem
CMTS Termination System
100Base-T, GbE
m1619ed_2
Residential Area
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DWDM Primer DWDM Network Solutions
Multiservice Operations • The user has to ability to select and control (fast
forward, pause, and start) content. Content examples
Multiservice Operations (MSO), shown in Figure 6-4, provide are movies or other special programs.
varied services to residential customers. These services include:
• Bandwidth (BW) requirements are bursty, since BW is
• Video only required when a user requests content.
• Voice Near Video on Demand
• Data Near Video on Demand (NVOD) is a for-fee delivery service that
• Other Services is provided at intervals and cannot be controlled after delivery
begins by the residential subscriber:
Video • The operator will broadcast popular movies in close
Their networks provide many kinds of broadcast video delivery intervals on multiple channels. The user has no control
systems. The transport of video is very important to MSO over the pausing or reviewing of the movie. Since the
operators and is the priority business of the network. The most movies are broadcast on different channels in 30
common digital video transport techniques are: minute intervals the user will only have to wait 30
minutes before they can begin viewing.
• DVB-ASI Compressed Video at 270 Mb/s
• Bandwidth requirements will be consistent since all
• Digital Video (SMPTE 259M) at 270 Mb/s movies are broadcast at the same time.
• Video over GbE at 1.250 Gb/s Subscription Video on Demand
• DV6000® at 2.380 Gb/s Subscription Video on Demand (SVOD) programs are selected in
MSO Video applications are described in the following advance by the residential subscriber, on an event basis.
paragraphs. Typically SVOD is:
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Satellite Feeds
Local Feeds
7500 7500
7500
4500
VOD Servers
Studio/Tape
Data 4500 4500
Voice
4500
Telephony
HDT TR-303
DS1s
Taps
Digital Digital Video
Video DVB-ASI, DV6000, GbE
Drops
Cable Modem
CMTS Termination System
100Base-T, GbE
m1619eh_2
Residential Area
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DWDM Primer DWDM Network Solutions
Data
Internet services have become a significant business for the
MSO. Transport of residential subscriber Internet and other
public communications data requirements is provided by use of
routers placed in the subscriber nodes, that communicate to the
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Lesson 7
DWDM Acronyms
DWDM Acronyms DWDM Primer
Acronym Description/Explanation
1R regenerator that reamplifies optical signal
2R regenerator that reamplify and reshape
3R regenerator that reamplify, reshape, and retime
4WM four-wave mixing (also called FWM) (impairment)
APD avalanche photodiodes
ATM Asynchronous Transfer Mode
AWG arrayed waveguide
BER bit error rate
BG Bragg grating
C-band optical band from 1530 to 1570 nanometers long
CS-RZ carrier suppressed-return to zero
CWDM course wavelength division multiplex/multiplexing
dB decibel (a unit for expressing the ratio of two amounts of electric or
acoustic signal power equal to 10 times the common logarithm of this
ratio)
dBm decibel per milliwatt (power ratio referenced to 1 milliwatt)
DCF dispersion compensation fiber
DCM dispersion compensation module (lumped dispersion)
DCN data communications network
DS dispersion shifted
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DWDM Primer DWDM Acronyms
Acronym Description/Explanation
DSF dispersion-shifted fiber
DWDM dense wavelength division multiplex/multiplexing
EDFA erbium-doped fiber amplifier
EDTFA tellurite-based EDFA (Tellurium is the source rare-earth ele-
ment.)
ELEAF Corning Expanded Large Effective Area Fiber (NZ-DSF)
ESD electrostatic discharge
FEC forward error correction
FNC Fujitsu Network Communications, Inc.
FWM four-wave mixing (also called 4WM) (impairment)
Gb/s gigabits per second
GHz gigahertz
GW symbol for gigawatt (one billion watts)
GS-EDFA gain-shifted erbium-doped fiber amplifier
GUI graphical user interface
ILA intermediate line amplifier
IP Internet Protocol
ISO International Organization of Standards
ITU-T International Telecommunication Union Telecommunication
Standardization Sector
LAN local area network
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Acronym Description/Explanation
L-band Optical band from 1570 to 1625 nanometers long
LEAF Corning Large Effective Area Fiber (NZ-DSF)
LS Corning NZ-DSF
MAC media access control
MB/s megabits per second
MMF multimode fiber
mW symbol for milliwatt power measurement
NDSF non–dispersion-sifted fiber
NE network element
NF noise figure
nm nanometer (unit of wavelength)
NRZ non–return to zero coding
NVM nonvolatile memory
NZ-DSF non–zero dispersion-shifted fiber (offset from zero point)
OADM optical add/drop multiplexer
OC optical channel
OOB-FEC out-of-band forward error control
OSI Open Systems Interconnection (standard set of protocols)
OSNR optical signal-to-noise ratio
OXC optical cross-connect
PIN simple photodiode
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DWDM Primer DWDM Acronyms
Acronym Description/Explanation
PMD polarization mode dispersion
PMDC polarization mode dispersion compensator
ps picosecond(s)
ps/nm picosecond(s) per nanometer
Q-factor measure of noise in a pulse
RAM random access memory
RFA Raman fiber amplifier
ROM read-only memory
RZ return-to-zero (coding)
S-band optical band from 1450 to 1500 nanometers
SBS Stimulated Brillouin scattering (impairment)
SDCC section data communications channel
SMF single-mode fiber
SMF-28 Corning SMF
SNR signal-to-noise ratio
SOA silicon optical amplifier
SONET Synchronous Optical Network
SPM self-phase modulation (impairment)
SRS stimulated Raman scattering (impairment)
SSMF standard SMF
Tb/s terabits per second
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Acronym Description/Explanation
TCP Transmission Control Protocol
TDFA thallium-doped fluoride-based amplifier
TDM time-division multiplex/multiplexing/multiplexer
TeraLight Alcatel NZ-DSF
TFF thin-film filter
TIB Technical Information Bulletin
TrueWave Classic Lucent non–zero dispersion-shifted fiber with offset
TrueWave Plus Lucent non–zero dispersion-shifted fiber with offset
TrueWave RS Lucent non–zero dispersion-shifted fiber with reduced slope
VIPA virtual IP address (routers)
VIPA virtual image phase array (compensator for dispersion)
VoIP Voice-over-Internet Protocol
W watt (symbol for watt power measurement)
WDM wavelength division multiplex/multiplexing/multiplexer
XPM cross-phase/modulation (impairment)
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Lesson 8
DWDM Terms
DWDM Terms DWDM Primer
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Lesson 9
9-2 FNC and FNC Customer Use Only May 21, 2004
DWDM Primer End of Course Evaluation
End of Course Evaluation 3. The terms retime, reamplify, and reshape describe ____
regenerators.
If you complete the DWDM Self Evaluation and get fewer than 12
answers are correct, you should review and retake the Self- (A) 1R
Evaluation until you do reach 12 or more right answers. The (B) 2R
answers to the Self-Evaluation follow the questions, and contain
links to the material in your self-study Tutorial. (C) 3R
(D) None of the above
DWDM Self-Evaluation
Circle the letter of your choice and then compare your answers
on the “Self-Evaluation Sheet (Electronic)” on page 41.
1. Which statement is true?
(A) DWDM systems cost more than installing more fibers.
(B) DWDM systems cannot carry multiservice traffic.
(C) DWDM systems are not used in SONET environments.
(D) DWDM systems cost a fraction of added fibers.
2. The five components of a DWDM network include transmitter,
receiver, optical amplifier, ___________________.
(A) multiplexer/demultiplexer and optical fiber
(B) SONET, voice-over-Internet Protocol, and dispersion
(C) All of the above
(D) None of the above
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4. You ________ see the light used in fiber-optic transmission. 8. OSNR stands for optical ________.
(A) can always (A) signal–no return
(B) cannot (B) signal-to-noise ratio
(C) look through 3-D glasses to (C) system–network ready
(D) none of the above (D) signal–network ready
5. Signal bandwidth for 10-Gb/s signals is _____ gigahertz
(GHz).
(A) 20
(B) 40
(C) 10
(D) 5
6. ____ FEC provides approximately _________ system gain.
(A) In-band, 9 dB
(B) Out-of-band, 6 dB
(C) All of the above
(D) None of the above
7. Laser chirp is ________________________________.
(A) not allowed in FNC equipment
(B) typically occurs between –1 GHz and +1 GHz
(C) offered by different companies
(D) none of the above
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Table 1: Answers
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