Download pdf - Chapter15 DWDM

E1E1--E2 (CFA) E2 (CFA)

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DWDMDWDM

WELCOME

• This is a presentation for the E1-E2 CFA Module for the

Topic: DWDM

• Eligibility: Those who have got the Up gradation from

E1 to E2.

• This presentation is last updated on 28-3-2011.• This presentation is last updated on 28-3-2011.

• You can also visit the Digital library of BSNL to see this

topic.


Agenda

• Introduction

• Development of DWDM Technology

• Varieties of WDM

• DWDM System Function

• Transmission Windows

• DWDM System Components

• Benefits of DWDM

• Conclusion


Introduction

• One of the major issues in the networking industry

today is tremendous demand for more and more

bandwidth.

• Before the introduction of optical networks, the reduced

availability of fibers became a big problem for theavailability of fibers became a big problem for the

network providers.

• Dense wavelength-division multiplexing (DWDM)

revolutionized transmission technology by increasing

the capacity signal of embedded fiber.


Introduction

• The existing SONET/SDH network architecture is best

suited for voice traffic rather than today’s high-speed data

traffic.

• To upgrade the system to handle this kind of traffic is

very expensive and hence the need for the developmentvery expensive and hence the need for the development

of an intelligent all-optical network.

• Dense wavelength division multiplexing (DWDM) is a

fiber-optic transmission technique that employs multiple

light wavelengths to transmit data in parallel through a

single fiber.For internal circulation of BSNL only

Introduction


Development of DWDM Technology

• Early WDM began in the late 1980s using the two widely

spaced wavelengths in the 1310 nm and 1550 nm (or

850 nm and 1310 nm) regions, sometimes called

wideband WDM.wideband WDM.

• The early 1990s saw a second generation of WDM,

sometimes called narrowband WDM, in which two to

eight channels were used.



• By the mid-1990s, dense WDM (DWDM) systems were

emerging with 16 to 40 channels and spacing from 100

to 200 GHz.

• By the late 1990s DWDM systems had evolved to the• By the late 1990s DWDM systems had evolved to the

point where they were capable of 64 to 160 parallel

channels, densely packed at 50 or even 25 GHz

intervals.




Varieties of WDM

1. WDM

– Traditional, passive WDM systems are widespread

with 2, 4, 8, 12, and 16 channel counts being the

normal deployments.

2. CWDM2. CWDM

– Today, coarse WDM (CWDM) typically uses 20-nm

spacing (3000 GHz) of up to 18 channels.

– The CWDM grid is made up of 18 wavelengths

defined within the range 1270 nm to 1610 nm spaced

by 20 nm.For internal circulation of BSNL only

Varieties of WDM

3. DWDM

– Dense WDM common spacing may be 200, 100, 50,

or 25 GHz with channel count reaching up to 128 or

more channels at distances of several thousand

kilometers with amplification and regeneration along

such a route.


Varieties of WDM


DWDM System Function

• Dense wavelength division multiplexing systems allow

many discrete transports channels by combining and

transmitting multiple signals simultaneously at different

wavelengths on the same fiber.

• In effect, one fiber is transformed into multiple virtual

fibers.

• So, if you were to multiplex 32 STM-16 signals into one

fiber, you would increase the carrying capacity of that

fiber from 2.5 Gb/s to 80 Gb/s.



• A key advantage to DWDM is that it's protocol and bit

rate-independent. DWDM-based networks can transmit

data in SDH, IP, ATM and Ethernet etc.

• Therefore, DWDM-based networks can carry different

types of traffic at different speeds over an optical

channel. DWDM is a core technology in an optical

transport network.



Any Speed---------------------------------Any Protocol



Transparent transmission



• Dense WDM common spacing may be

– 200 GHz or 1.6 nm,

– 100 GHz or 0.8 nm,

– 50 GHz or 0.4 nm,

– 25 GHz with channel count reaching up to 128 or

more channels at distances of several thousand

kilometers with amplification and regeneration along

such a route.




Supports optical data protocols including SDH, ESCON,

FICON, Fibre Channel, GigE, Digital Video, Fast Ethernet etc.

Transmission Windows

In Future, the

communication window

1280~1625nm

C-band：：：：1525~1565nm

L-band ：：：：1565~1625nm


Transmission Windows


Overview of DWDM

• DWDM systems in enabling service providers to

accommodate consumer demand for ever-increasing

amounts of bandwidth.

• DWDM allows the transmission of different formats

like Internet protocol (IP), asynchronous transferlike Internet protocol (IP), asynchronous transfer

mode (ATM), and synchronous digital hierarchy

(SDH), respectively, over the optical layer.


DWDM System Components

• Transmitter (transmit transponder)

• Optical Multiplexer/ demultiplexer

• Optical Amplifier

• Optical fiber (media)


• Receiver (receive transponder)


• Transmitter (transmit transponder)

– Changes electrical bits to optical pulses

– Uses a narrowband laser to generate the optical

pulse



• Optical Multiplexer/ demultiplexer

– Combines/separates discrete wavelengths



• Optical Amplifier

– Pre-amplifier, Post-amplifier and In line amplifiers

(ILA)

– EDFA (Eribium Doped Fiber Amplifier) is the

most popular amplifier.


most popular amplifier.


• Optical Fiber (Media)

– Transmission media to carry optical pulses

– Many different kinds of fiber are used



• Receiver (receive transponder)

– Changes optical pulses back to electrical bits

– Uses wideband laser to provide the optical pulse


Benefits of DWDM

• Increases bandwidth (speed and distance)

• Does not require replacement or upgrade their existing

legacy systems

• Provides "next generation" technologies to meet growing

data needs

• Less costly in the long run because increased fiber

capacity is automatically available; don't have to upgrade

all the time


Conclusion

• DWDM promises to solve the "fiber exhaust" problem

and is expected to be the central technology in the all-

optical networks of the future.

• This technology responds to the growing need for• This technology responds to the growing need for

efficient and capable data transmission by working with

different formats, such as SONET/SDH, while increasing

bandwidth.


TThank hank yyou!ou!


TThank hank yyou!ou!