DENSE WAVELENGTH DIVISION MULTIPLEXING

PRESENTED TO DR.SAPNA GAMBHIR ASSOCIATE PROF. CSE DEPTT. YMCAUST.FBD.

PRESENTED

BY PRITI RANI MNW-891-2K11 MTECH(CN) YMCAUST.FBD

CONTENTS

INTRODUCTIONVARIETIES OF WDMDWDM TECHNOLOGYHISTORY OF DWDMDWDM SYSTEM AND COMPONENTSTOPOLOGY

CONT…

TRANSMISSION CHALLENGESMARKET DYNAMICFUTUREAPPLICATIONSBENEFITSREFERNCES

INTRODUCTIONOne of the major issues in the networking industry today is tremendous demand for more and more bandwidth.

With the development of Optical network and the use Dense Wavelength Division Technology, a new and probably, a very

crucial milestone is being reached network evaluation.

OPTICAL NETWORKINGOptical networks are high-capacity telecommunications networks based on optical technologies.

The origin of optical networks is linked to Wavelength Division Multiplexing (WDM) which arose to provide additional capacity on existing fibers.

CLASSIFICATION OF OPTICAL NETWORK

FIRST GENERATION: Networks use microwave technology based.

SECOND GENERATION: Networks use microwave links with optical fibers.

THIRD GENERATION: Networks employ Wavelength Division Multiplexing technology.

What is DWDM?

Dense Wavelength Division Multiplexing (DWDM) is a fiber-optic transmission

technique.

It involves the process of multiplexing many different wavelength signals onto a single fiber. So each fiber has a set of parallel optical channels each using slightly different light wavelengths.

CONT..

It employs light wavelengths to transmit data parallel-by-bit or serial-by-character.

DWDM is a very crucial component of optical networks that will allow the transmission of data: voice, video over the optical layer.

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It transmits multiple data signals using different wavelengths of light through a single fiber.

Incoming optical signals are assigned to specific frequencies within a designated frequency band.

The capacity of fiber is increased when these signals are multiplexed onto one fiber

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Transmission capabilities is 4-8 times of TDM Systems with the help of Erbium doped optical amplifier.EDFA’s : increase the optical signal and don’t have to regenerate signal to boost it strength.

It lengthens the distances of transmission to more than 300 km before regeneration .

Why DWDM?

Unlimited Transmission CapacityTransparencyScalabilityDynamic Provisioning

Is DWDM Flexible?

DWDM is a protocol and bit rate independent hence, data signals such as ATM, SONET and IP can be transmitted through same stream regardless their speed difference.

The signals are never terminated within the optical layer allows the independence of bit rate and protocols,allowing DWDM technology to be integrated with existing equipment in network.

Hence, there’s a flexibility to expand capacity within any portion of their networks.

Is DWDM Expandable?

“ DWDM technology gives us the ability to expand out fiber network rapidly to meet growing demands of our customer”, said Mike Flynn, group President for ALLTEL’s communications operations.

DWDM coupled with ATM simplifies the network, reduce network costs and provide new services.

They can add current and new TDM systems to their existing technology to create a system with virtually endless capacity expansion

DISADVANTAGES

Not cost effective for low channel numbers Sonet/sdh network management system

Are not well equipped to handle dwdm topologies

DWDM SYSTEM

Comparison of TDM, WDM, and DWDM multiplexing capabilities

Multiplex

Scalable

Protocolindependent

Bit rateindependent

Channels peroptical fiber

Opticalsystemcapacity

Equivalent DS-3connections

TDM No No No 1 2.5 Gbit/s

48

WDM Yes Yes Yes 2 5 Gbit/s 96

DWDM Yes Yes Yes 16 N/A atpublication

N/A atpublication

EVOLUTION OF DWDM

A picture representing the really cool analogy

Before

After TDM (cars go faster)

After DWDM (all the lanes are used)

Example of Speeds

Currently Lucent DWDM systems support transmissions of 160 separate wavelengths. Each wavelength is capable of supporting a signal of up to 10 Gbps.

The total combined bandwidth is

1.6 trillion bits per second.

This is greater than the speed of one million T-1 connections.

How DWDM saves $$

In addition to saving money on fiber cables, DWDM also saves money on optical repeating equipment Because one fiber is used instead of many, one

repeater can be used in place of many For example: you need 16 OC-3 carrier lines to go

1000 miles and repeaters are needed every 100 miles…If you didn’t use DWDM, you would need 16

thousand miles of fiber and 160 repeatersWith DWDM, you need only 1 thousand miles of

fiber and 10 repeaters

A picture of How DWDM saves $$

Before DWDM

After DWDM

Signal Quality

Optical Signal to Noise RatioOptical Spectrum Analyzer

Optical Signal

Noise Floor

DWDM Components

Transmitter : - Changes electrical bits to optical pulses- Is frequency specific- Uses a narrowband laser to generate the optical pulse 5.2 Multiplexer/ Demultiplexer:- Combines/separates discrete wavelengths5.3 Amplifier:- Pre-amplifier boosts signal pulses at the receive side- Post-amplifier boosts signal pulses at the transmit side

5.4 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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5.5 Receiver (receive transponder)- Changes optical pulses back to electrical bits- Uses wideband laser to provide the optical pulse

DWDM Mesh Designs

Advantages of DWDM Point to Point Systems

The DWDM point-to-point architecture is simple to build and troubleshoot .It enables protocol transparency, increme-ntal growth, and capacity expansion over time, while dramatically reducing start-up costs. Point-to-point solutions are also extremely efficient.No amplifiers or additional equipment required.

Transmission Challenges

Attenuation Attenuation is caused by :- intrinsic factors primarily scattering and absorption- extrinsic factors, including stress from the manufacturing process, the environment, and physical bendingRayleigh scattering - is an issue at shorter wavelengths

Rayleigh Scattering

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Attenuation due to absorption

- is an issue at longer wavelengths - the intrinsic properties of the material - impurities in the glass, and any atomic defects in the glass.

These impurities absorb the optical energy, causing the light to become dimmer.

Absorption

Dispersion

Dispersion is the spreading of light pulses as they travel down optical fiber. Dispersion results in distortion of the signal, which limits the bandwidth of the fiber.

Two general types of dispersionChromatic Dispersion - is linear Chromatic dispersion occurs because different wavelengths propagate at different speeds. Increases as the square of the bit rate.

Polarization Mode Dispersion - is nonlinear. Polarization mode dispersion (PMD) is caused by ovality of the fiber shape as a result of the manufacturing process or from external stressors.

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Changes over time PMD is generally not a problem at speeds below OC-192.

Smearing of the signal

Fiber Non Linear ties

Because nonlinear effects tend to manifest themselves when optical power is very high, they become important in DWDM.

These nonlinearities fall into two broad groups:

- scattering phenomena

- refractive index phenomena

Future of DWDM

What the future holdsTwo-way video communication Digital video for our everyday use at home and at work.Change from voice telephony to digital data heavy with video to require multiplying backbone transmission capacity.The Ultimate Squeeze - reducing the “space” between wavelengths - expanding the range of transmission wavelengths

- better EDFAs

Develop better equipment for switching and manipulating the various wavelengths after the signal emerges from the optical “pipe.”

WDM is creating huge new information pipelines that will bring better service at lower cost. But the real information revolution won’t come until cheap WDM

pipelines reach individual residences.

Applications of DWDM

DWDM is ready made for long-distance telecommunications operators that use either point-to-point or ring topologies. Building or expanding networks Network wholesalers can lease capacity, rather than entire fibers. The transparency of DWDM systems to various bit rates and protocols.Utilize the existing thin fiber DWDM improves signal transmission

Summary

DWDM was introduced to increase bandwidth by better utilizing existing fiber optic cabling

DWDM is able to place many network formats of different speeds on the same fiber optic cable

Optical Add-Drop Multiplexers and Cross Connects are what places the digital signals on the fiber

Less cable and therefore less optical repeating equipment is needed for DWDM

DWDM SAVES $$$

THANKYOU FOR YOUR ATTENTION