DENSE WAVELENGTH DIVISION MULTIPLEXING

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DENSE WAVELENGTH DIVISION MULTIPLEXING

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

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

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CONTENTS

• INTRODUCTION
• VARIETIES OF WDM
• DWDM TECHNOLOGY
• HISTORY OF DWDM
• DWDM SYSTEM AND COMPONENTS
• TOPOLOGY

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CONT

• TRANSMISSION CHALLENGES
• MARKET DYNAMIC
• FUTURE
• APPLICATIONS
• BENEFITS
• REFERNCES

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INTRODUCTION

• One 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.

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OPTICAL NETWORKING

• Optical 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.

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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.

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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.

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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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CONT..

• 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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CONT..

• Transmission capabilities is 4-8 times of TDM
  Systems with the help of Erbium doped optical
  amplifier.
• EDFAs increase the optical signal and dont
  have to regenerate signal to boost it strength.
• It lengthens the distances of transmission to
  more than 300 km before regeneration .

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Why DWDM?

• Unlimited Transmission Capacity
• Transparency
• Scalability
• Dynamic Provisioning

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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, theres a flexibility to expand capacity
  within any portion of their networks.

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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 ALLTELs 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

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DISADVANTAGES

• Not cost effective for low channel numbers
• Sonet/sdh network management system
• Are not well equipped to handle dwdm topologies

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DWDM SYSTEM
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Comparison of TDM, WDM, and DWDM multiplexing
capabilities
Multiplex Scalable Protocol independent Bit rate independent Channels per optical fiber Optical system capacity Equivalent DS-3 connections
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 at publication N/A at publication
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EVOLUTION OF DWDM
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A picture representing the really cool analogy
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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.

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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 didnt use DWDM, you would need 16
  thousand miles of fiber and 160 repeaters
• With DWDM, you need only 1 thousand miles of
  fiber and 10 repeaters

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A picture of How DWDM saves

• Before DWDM

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Signal Quality

• Optical Signal to Noise Ratio
• Optical Spectrum Analyzer

Optical Signal
Noise Floor
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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 wavelengths
• 5.3 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 144256 fibers

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CONT

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

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DWDM Mesh Designs
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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.

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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 bending
• Rayleigh scattering - is an issue at shorter
  wavelengths

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Rayleigh Scattering
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CONT

• 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.

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Absorption
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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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CONT

• 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

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Future of DWDM

• What the future holds
• Two-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

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• 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 wont come until
  cheap WDM pipelines reach individual residences.

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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

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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

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THANKYOU FOR YOUR ATTENTION