Dwdm Introduction

7/30/2019 Dwdm Introduction

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Monday, May 20, 2013 ALTTC / TX-1 / WDMD N Sahay

1

INTRODUCTION

TO DWDM


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(D)WDM : CONTENTS

THE NEED FOR DWDM :

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 FEATURES : AD(DISAD)VANTAGES

DWDM SYSTEMS AT PRESENT

OPTICAL AMPLITIERS

DWDM COMPONENTS

NMS

OPTICAL BANDS

STANDARD WAVELENGTHS: ITU GRID

DWDM APPLICATIONS :

BENEFIT TO OPERATORS

NEW ISSUES BEFOR PLANNERS


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3

FIBRE EXHAUST

2.5- Gbit/s

2.5- Gbit/s

2.5- Gbit/s

2.5- Gbit/s

transmitter

2.5-Gbit/s2.5 Gbit/s

2.5 Gbit/s

reciever

LAY NEW FIBRE AND PUT NEW SYSTEMS


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4

FIBRE EXHAUST

2.5- Gbit/s

2.5- Gbit/s

2.5- Gbit/s

2.5- Gbit/s

transmitter

2.5-Gbit/s

2.5 Gbit/s

2.5 Gbit/s

reciever

INSTAL HIGHER BITRATE TDM

EXPENSIVE, NEW FIBRE NEEDED

10-Gbit/s 10-Gbit/s10-Gbit/s

transmitter regenerator reciever


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5

FIBRE EXHAUST

DEPLOY DWDM

2.5-Gbitt/s

transmitter

M

U

X

D

E

M

U

X

10-Gbit/s 10-Gbit/s10-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

transmitter

2.5-Gbit/s

2.5 Gbit/s

2.5 Gbit/s

reciever

2.5- Gbit/sreciever

2

1

3

4

2

1

3

4

2.5- Gbit/sreciever

2.5- Gbit/sreciever

2.5- Gbit/sreciever

2.5-Gbitt/stransmitter

2.5-Gbitt/s

transmitter

2.5-Gbitt/s

transmitter


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6

EVOLUTION OF DWDM

Late

1990s

64-160 channels

25-50 GHZ spacing

Mid1990s

16-40 channels 100-200 GHz spacing

Dense WDM, integrated systems withNetwork Management, add-drop functions.

Early

1990s

2-8 channels passive

WDM 200-400 GHz spacing

WDM components/parts

Late

1980s

2 channels Wideband

WDM 1310 nm, 1550 nm


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ACHIEVING HIGHER BANDWIDTH

THREE POSSIBLE SOLUTIONS

INSTAL NEW FIBRE

INVEST IN NEW TDMTECHNOLOGIES TO

ACHIEVE HIGHER

BANDWIDTH. DEPLOY DWDM

EXPENSIVE

VERYEXPENSIVE

REQUIRE NEW

TYPE FIBRE

ECONOMICA

L


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THE CHALLENGE:Continuous growth in trafficCALLS 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

Tx RxMUX DEMUX

OFAWD

M

W

D

M

2.

.

.

.

1

16

TRANSPONDERS

OPTICAL

SIGNALS.

STM-1

STM-4

STM-16

ATM

IP


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Wayside Optical Add/Drop Multiplexer

TM TMWDM

MUX

WDM

DEMU

X2

15

16

1

1-4 5-8

O

A

O

A


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Optical Add/Drop

Multiplexing

1 12 2 2 2

Configurable

OADM :1 or2

1 12 2 2 2

1 1

fixed OADM:

2

OADM : Optical Add/Drop Multiplexer

Terminal Equipt Terminal EquiptIn-Line Amplifier


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OADM Connectivity

29 express ch

32 ch

WDM

Omnibus

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 ---> Limited Nes -->

Alarm Storm


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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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OPTICAL NETWORK ELEMENTS

TP

TP OA

ODEM

UX

OMUX

OADM OXC


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TRANSPONDER / TRANSLATOR /

WAVELENGTH CONVERTOR

O/E E/OElectricalREGENERATION

OPTIONAL

REGENERATOR


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Optical Multiplexers & Filters

W\L FILTER

W\L

MULTIPLEXER

W\L ROUTER


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OPTICAL ADD DROP MUX

COUPLER

D M

CIRCULATOR


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OPTICAL CROSSCONNECT

SWITCH

MATRIX

TTTT

T

TTT

WAVELENGTH

ADAPTATIONTRIBUTARY

LINKS

INPUT

FIBRE

LIN

KS


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OPTICAL AMPLIFIERS

Pump

laser

Pump

laser

Erbium-doped

Fiber-(10-50 m)

Isolator

Coupler Coupler

Isolator


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NMS FOR DWDM SYSTEMS

NMS IN CONVENTIONAL SDH SYSTEMS:

DCC: TIME SLOTS

DWDMNO 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 In-line Amplifier

Tx 1

Tx 2

Tx 3

Tx 4

Tx 5

Tx 6

Tx 7

Tx 8

D

ATAIN

1

2

3

4

5

6

7

8

Rx

Rx

Rx

Rx

Rx

Rx

Rx

Rx

1

2

3

4

5

6

7

8

Line Terminal Equipment

+ supervisory

Tx sup

System Control

Processor

Rx Tx

OSC

Network Management Network Management

System Control

Processor

Rx sup


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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 spacings of 200, 100, 50 GHz for different applications


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ITU-T BAND ALLOCATION

Optical

Supervisory

channel

1500 1520 1530 1542 1547 1560 1620

RED

BAND

C BAND L BAND

BLUE

BAND

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.

ITU T G 692 Frequency Grid


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Monday, May 20, 2013 ALTTC / TX-1 / WDMD N Sahay 29

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 1539.77 193.4 1550.12

ITUT G.692 Frequency Grid


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LIMITATIONS

DWDM TRANSMISSION IS ANALOG.THE IN LINE AMPLIFIERS AREALSO ANALOG.THIS IMPLIES THAT THE SIGNAL TO

NOISE RATIO WORSENS WITHDISTANCE.

TO KEEP THE BER WITHIN LIMITS,THE SIGNALS ARE REQUIRED TO BE

3R PROCESSED IN ELECTRICALDOMAIN.

FIBRE DISPERSION IS ANOTHERLIMITATION.


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LIMITATIONS

THE MAXIMUM DISTANCE IS 640 KmsMADE OF 8 SPANS OF 80 Kms. THE

ASSUMPTIONS ARE:

* FIBRE ATT INCLUDING SPLICELOSS IS 0.28 dB/km

* SPAN LOSS OF 22 dB.

* TOTAL DISPERSION IS LESSTHAN 12800 ps/nm.


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Long DistanceLonger Regenerator spacing: Hundreds toThousands 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

New Applications with DWDM


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Metropolitan Area Network

Unlimited Bandwidth, bit rate and format

transparencyEfficient Bandwidth use and Management



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High speed parallel Data TransportCertain Computer Applications Require that

Computer Centres 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 Benefitsall Delay Sensitive Applications



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Wavelength LeasingNetwork 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 Customers Bandwidth requirements arecleanly separated from the providers core

Network Needs.



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Monday May 20 2013 ALTTC / TX 1 / WDM 36

Thank You

Dwdm Introduction

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