Introduction to dwdm
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INTRODUCTION TO DWDM. 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

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INTRODUCTION TO DWDM

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Introduction to dwdm

INTRODUCTION TO DWDM

ALTTC/TX-I/DWDM


Introduction to dwdm

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

ALTTC/TX-I/DWDM


Introduction to dwdm

2.5- Gbit/s

2.5-Gbit/s

2.5- Gbit/s

2.5 Gbit/s

2.5- Gbit/s

2.5 Gbit/s

2.5- Gbit/s

reciever

transmitter

FIBRE EXHAUST

10-Gbit/s

10-Gbit/s

10-Gbit/s

transmitter

regenerator

reciever

INSTAL HIGHER BITRATE TDM

EXPENSIVE, NEW FIBRE NEEDED

ALTTC/TX-I/DWDM


Introduction to dwdm

FIBRE EXHAUST

10-Gbit/s

10-Gbit/s

10-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

2.5- Gbit/s

2.5 Gbit/s

2.5- Gbit/s

2.5- Gbit/s

2.5- Gbit/s

2.5- Gbit/s

2.5- Gbit/s

DEMUX

reciever

reciever

reciever

reciever

reciever

transmitter

MUX

2.5-Gbitt/s

2.5-Gbitt/s

2.5-Gbitt/s

2.5-Gbitt/s

transmitter

transmitter

transmitter

transmitter

λ1

λ1

λ2

λ2

λ3

λ3

λ4

λ4

DEPLOY DWDM

ALTTC/TX-I/DWDM


Introduction to dwdm

64-160 channels

25-50 GHZ spacing

Late

1990’s

16-40 channels 100-200 GHz spacing

Dense WDM, integrated systems with

Network Management, add-drop functions.

Mid

1990’s

2-8 channels passive

WDM 200-400 GHz spacing

WDM components/parts

Early

1990’s

Late

1980’s

2 channels Wideband

WDM 1310 nm, 1550 nm

EVOLUTION OF DWDM

ALTTC/TX-I/DWDM


Introduction to dwdm

THREE POSSIBLE SOLUTIONS

  • INSTAL NEW FIBRE

  • INVEST IN NEW TDM

  • TECHNOLOGIES TO

  • ACHIEVE HIGHER

  • BANDWIDTH.

  • DEPLOY DWDM

EXPENSIVE

VERY

EXPENSIVE

REQUIRE NEW

TYPE FIBRE

ECONOMICAL

ACHIEVING HIGHER BANDWIDTH

ALTTC/TX-I/DWDM


Introduction to dwdm

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

ALTTC/TX-I/DWDM


Introduction to dwdm

DWDM BASICS

DWDM

MULTIPLEXER

SINGLE FIBRE

SDH OPTICAL SIGNALS

NEW REQUIREMENTS:

ALTTC/TX-I/DWDM


Introduction to dwdm

Tx

Rx

OPTICAL

SIGNALS.

DEMUX

MUX

  • 1

STM-1

STM-4

STM-16

ATM

IP

OFA

  • 2

    .

    .

    .

    .

W

W

D

D

M

M

  • 16

TRANSPONDERS

BLOCK SCHEMATIC

ALTTC/TX-I/DWDM


Introduction to dwdm

WDM MUX

WDM DEMUX

1

OA

OA

2

15

16

1-4

5-8

Wayside Optical Add/Drop Multiplexer

TM

TM

ALTTC/TX-I/DWDM


Introduction to dwdm

Optical Add/Drop Multiplexing

l1

l1

Configurable OADM :1or2

l1

l2

l2

l2

l2

l1

l1

l2

l2

l2

l2

l1

Terminal Equipt

In-Line Amplifier

Terminal Equipt

fixed OADM:2

OADM : Optical Add/Drop Multiplexer

ALTTC/TX-I/DWDM


Introduction to dwdm

OADM Connectivity

  • Omnibus

29 express ch

32 chWDM

  • From terminal to OADM, or from OADM to OADM

ALTTC/TX-I/DWDM


Differences from old system

DIFFERENCES FROM OLD SYSTEM

  • REGs

  • FIBRES REQUIREMENT

  • LASERS

  • TYPES OF COMPONENTS

  • CAPACITY

  • FIBRE TRANSMISSION BEHAVIOUR

ALTTC/TX-I/DWDM


Introduction to dwdm

ADVANTAGES OF DWDM

ALTTC/TX-I/DWDM


Introduction to dwdm

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 ExpansionsDemand

  • Simpler Operations : Embedded DCC

ALTTC/TX-I/DWDM


Introduction to dwdm

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

ALTTC/TX-I/DWDM


Dwdm components

DWDM Components

  • Transmit

  • Receive

  • Repeater

  • Add Drop

  • Distribution: Cross connects

ALTTC/TX-I/DWDM


Introduction to dwdm

OPTICAL NETWORK ELEMENTS

TP

OA

OADM

OXC

TP

OMUX

ODEMUX

ALTTC/TX-I/DWDM


Introduction to dwdm

OPTIONAL

REGENERATOR

Electrical

REGENERATION

O/E

E/O

TRANSPONDER / TRANSLATOR / WAVELENGTH CONVERTOR

ALTTC/TX-I/DWDM


Introduction to dwdm

Optical Multiplexers & Filters

W\L FILTER

W\L

MULTIPLEXER

W\L ROUTER

ALTTC/TX-I/DWDM


Introduction to dwdm

OPTICAL ADD DROP MUX

M

D

COUPLER

CIRCULATOR

ALTTC/TX-I/DWDM


Introduction to dwdm

OPTICAL CROSSCONNECT

T

SWITCH

MATRIX

T

T

T

INPUT FIBRE

LINKS

OUTPUT FIBRE

LINKS

T

T

T

T

WAVELENGTH ADAPTATION

TRIBUTARY LINKS

ALTTC/TX-I/DWDM


Optical amplifiers

OPTICAL AMPLIFIERS

Isolator

Isolator

Coupler

Coupler

Erbium-doped

Fiber-(10-50 m)

Pump

laser

Pump

laser

ALTTC/TX-I/DWDM


Nms for dwdm systems

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

ALTTC/TX-I/DWDM


Introduction to dwdm

Line Terminal Equipment

In-line Amplifier

Line Terminal Equipment

Rx

Tx 1

Rx

Tx 2

1

1

Rx

Tx 3

2

2

Rx

Tx 4

DATA OUT

DATA IN

3

3

Rx

Tx 5

4

4

Rx

Tx 6

5

5

Rx

Tx 7

6

6

Rx

Tx 8

7

7

Rx Tx

OSC

Tx sup

Rx sup

8

8

System ControlProcessor

System ControlProcessor

Network Management

Network Management

Optical Supervisory Channel(OSC)

 + supervisory

ALTTC/TX-I/DWDM


Optical bands

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

ALTTC/TX-I/DWDM


Introduction to dwdm

ITU-T BAND ALLOCATION

C BAND

L BAND

Optical

Supervisory

channel

RED

BAND

BLUE

BAND

1500 1520

1530 1542 1547 1560 1620

  • 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.

ALTTC/TX-I/DWDM


Introduction to dwdm

ITU –T G.692 Frequency Grid

ALTTC/TX-I/DWDM


Introduction to dwdm

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.

ALTTC/TX-I/DWDM


Introduction to dwdm

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.

ALTTC/TX-I/DWDM


New applications with dwdm

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

ALTTC/TX-I/DWDM


New applications with dwdm1

New Applications with DWDM

  • Metropolitan Area Network

    • Unlimited Bandwidth, bit rate and format transparency

    • Efficient Bandwidth use and Management

ALTTC/TX-I/DWDM


New applications with dwdm2

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

ALTTC/TX-I/DWDM


New applications with dwdm3

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.

ALTTC/TX-I/DWDM


Thank you

Thank You

ALTTC/TX-I/DWDM


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