CHAPTER 3 Lecturer Complete

8/3/2019 CHAPTER 3 Lecturer Complete

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Wavelength

Division

Multiplexer

Wavelength

Division

Demultiplexer1A

2B

1 X

2Y1 + 2

Fibre

Wavelength Division Multiplexing

Multiple channels of information carried over the same fibre, eachusing an individual wavelength

Typically one channel utilises 1320 nm and the other 1550 nm

Broad channel spacing, several hundred nm


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Wavelength

Division

Multiplexer

Wavelength

Division

Demultiplexer1A

23

B

C

1X

23

Y

Z1 + 2 + 3

Fibre

Dense Wavelength DivisionMultiplexing

Multiple channels of information carried over the same fibre, each using anindividual wavelength

DWDM is WDM utilising closely spaced channels

Channel spacing reduced to 1.6 nm and less

Cost effective way of increasing capacity without replacing fibre

Commercial systems available with capacities of 32 channels and upwards; >80 Gb/s per fibre


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WDM vs DWDM

WDM DWDM

Channel spacing Broad spacing

Cost per channel Low high

Number of channels

delivered

2 Hundreds of

channels

Best application PON Long haul


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Channel frequency (wavelength) &

spacingBand Wavelength (nm)

820 - 900

1260 1360

New Band 1360 1460

S-Band 1460 1530

C-Band 1530 1565L-Band 1565 1625

U-Band 1625 1675


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Main component in DWDMsystem

Terminal multiplexer

Intermediate line repeater

Optical add/drop multiplexer (optical odm)

Terminal demultiplexer

Optical supervisory channel (osc)


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The terminal multiplexer

actually contains one

wavelength converting

transponder for each

wavelength signal it will

carry.

WavelengthsConverted viaTransponders

WavelengthMultiplexedSignals

DWDMMux


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The terminal also

contains other modules

as the Optical

Supervisory Channel

(OSC), Automatic Laser

Control (ALC), Line

Amplifier (LOFA) andthe Band Mux/Demux,

splitter and filters


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Transponder

Converts broadband optical signals to a

specific wavelength via optical to electrical to

optical conversion (O-E-O)

Low Cost

IR/SR Optics

Wavelengths

Converted

1

From OpticalOLTE

To DWDM MuxOEO

OEO

OEO

2

n


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Transponder

Luminet DWDM

Transponder


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Intermediate line repeater

is placed approx. every 80 100 km for

compensating the loss in optical power,

while the signal travels along the fiber.

The signal is amplified by an EDFA, whichusually consists of several amplifier

stages.

Optical Amplifier

(EDFA)


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Optical add/drop multiplexer(OADM)

It is often desirable to be able to remove

or insert one or more wavelengths at

some point along this span.

the OADM can remove some wavelength

while passing others on.


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Optical add/drop multiplexer(OADM)

DropChannel

AddChannel

Add &Drop

channel

OADMs allow flexible add/drop of channels


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Terminal demultiplexer

The terminal

demultiplexer breaks

the multi-wavelength

signal back intoindividual signals and

outputs them on

separate fibres forclient-layer systems

(such as SONET/SDH)

to detect

DWDM

Demux

WavelengthMultiplexedSignals

Wavelengthsseparated intoindividual ITUSpecificlambdas


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Optical supervisory channel(OSC)

The OSC carries information about the multi-wavelength optical signal as well as remoteconditions at the optical terminal.

The outofband Optical Supervisory Channel(OSC) allows the supervision of all the NEsalong the WDM path.

Moreover it gives some orderwires (data

channel and voice channel) to the users. Out-of-band, means the OSC is using a different bandthan the DWDM system is normally running in, whichnormally would be the U-band (1625 1675 nm).


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DWDM System

Transmitters

DWDM

Multiplexer

Line

Repeater

DWDMDeMultiplexer

ReceiversAdd/Drop

Mux/Demux

Optical

fibre


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SONET/SDH

SDH (Synchronous Digital Hierarchy) and SONET(Synchronous Optical NETwork) are standards forinterfacing optical networks.

Simple multiplexing processes Easy access to various signals in a multiplexed high bit rate

signal A flexible and efficient way of networking Network Distribution: Add/Drop capability Network survivability: APS (Automatic Protection

Switching)

Traffic Cross connection: capacity management,bandwidth management and protection route diversity Support advance Network Management System (OAM&P)

Overhead bits for Fault, Configuration, PerformanceMonitoring, Security and Accounting management

Standardized interface can support multi vendor

interworking, international connection and many differentservices; i.e. ATM, IP


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SONET/SDH Characteristic

OpticalLevel

SONETElectrical

Level

SDHEquivalent

Line Rate(Mbps)

PayloadRate

(Mbps)

OverheadRate

(Mbps)

SONETCapacity

SDHCapacity

OC-1 STS-1 51.840 50.112 1.728 28 DS-1s or 1 DS-3

21 E1s

OC-3 STS-3 STM-1 155.520 150.336 5.184 84 DS-1s or 3 DS-3s

63 E1s or1 E4

OC-12 STS-12 STM-4 622.080 601.344 20.736 336 DS-1s or 12 DS-3s

252 E1s or4 E4s

OC-48 STS-48 STM-16 2488.320 2405.376 82.944 1,344 DS-1s or 192 DS-3s

1,008 E1s or16 E4s

OC-192 STS-192 STM-64 9953.280 9621.504 331.776 5,376 DS-1s or 192 DS-3s

4,032 E1s or64 E4s

Note:Although an SDH STM-1 has the same bit rate as the SONET STS-3, the two signals contain different frame structures.STM = Synchronous Transport Module (ITU-T)STS = Synchronous Transfer Signal (ANSI)OC = Optical Carrier (ANSI)


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SONET

Synchronous Optical NETwork

Standard for digital optical transmission

Standardized by ANSI T1X1 North American TDM physical layer

standard for optical fiber communications

8000 frames/sec. (Tframe = 125 sec) Compatible with North American digital

hierarchy


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SDH

SDH (Synchronous Digital Hierarchy)elsewhere

Needs to carry E1 and E3 signals

Compatible with SONET at higher speeds

Greatly simplifies multiplexing in networkbackbone

OA&M support to facilitate networkmanagement

Protection & restoration


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What is different about SDHvs. SONET?

Together they are a set of global standards that interfaceequipment from different vendors. SDH is basically theinternational version of SONET, and SONET can be thought ofas the North American version of SDH.

There are some slight differences between SONET and SDH.

The main differences are in the basic SDH and SONET frameformats, but SDH and SONET are essentially identical beyondthe STS-3 signal level. The base signal for SONET is STS-1and the base signal for SDH is STM-1. STS-3c is equivalent to

STM-1 and the lower tributaries can be mapped interchangeablybetween the two formats from that point on.


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What is different about SDHvs. SONET? (Cont)

In SDH, both electrical and optical signals are referred to asSTM signals.

In SONET, however, electrical signals are called STS and

optical signals are referred to as OC.


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SONET network


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SONET/SDH signals

Identify SONET/SDH signals???STM = Synchronous Transport Module (ITU-T)STS = Synchronous Transfer Signal (ANSI)OC = Optical Carrier (ANSI)


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SONET/SDH rates

SDHSDHSDHSDH Bit RateBit RateBit RateBit Rate SONETSONETSONETSONET

STM-1STM-1STM-1STM-1

STM-64STM-64STM-64STM-64 OC-192OC-192OC-192OC-192

OC-3OC-3OC-3OC-3

9.95Gb/s9.95Gb/s9.95Gb/s9.95Gb/s

155Mb/s155Mb/s155Mb/s155Mb/s

STM-4STM-4STM-4STM-4 OC-12OC-12OC-12OC-12622Mb/s622Mb/s622Mb/s622Mb/s

STM-16STM-16STM-16STM-16 OC-48OC-48OC-48OC-482.48Gb/s2.48Gb/s2.48Gb/s2.48Gb/s

STM-0STM-0STM-0STM-0 OC-1OC-1(STS-1)(STS-1)OC-1OC-1(STS-1)(STS-1)51Mb/s51Mb/s51Mb/s51Mb/s


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SONET/SDH devices STS MUX/DEMUX

Multiplexer equipments are one of the baseelements of the network.

The role of a multiplexer equipment is to insert

low bit rate tributaries inside the SDH/SONETframe (mapping process) and conversely todrop the tributaries from the SDH/SONET frame(demapping process).

It is necessary to check that no error occursduring the mapping/demapping process and thatthe integrity of the tributary is guaranteed.


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SONET/SDH devices STS MUX/DEMUX


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SONET/SDH devices Regenerator

Digital signal regeneration

Simplest SONET element. Perform 3R

regeneration

Allows to overcome distance limit at the physicallayer

Receives the input stream, and regenerates the

section overhead before retransmitting theframe. Does not modify Line and Path overhead

(behaves differently from an Ethernet repeater)


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SONET/SDH devices ADD/DROP MUX

Dropping and inserting tributaries

Multiplexes different tributaries over a single

OCN

The add/drop operation allows to elaborate,add/drop only signal that must be managed

Transit traffic is forwarded without the need of

particular operation.

It manages alternate routing in case of fault


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SONET/SDH devices ADD/DROP MUX


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SONET/SDH devices Terminal

(de-)multiplexes between multiple low-

speed signals and a high-speed signal

CHAPTER 3 Lecturer Complete

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