Presentation is loading. Please wait.

Presentation is loading. Please wait.

Fiber Systems Dense Wavelength Division Multiplexing (DWDM) Alpina Kulkarni Optical Communications (EE566) Dr. Paolo Liu Electrical UB.

Similar presentations


Presentation on theme: "Fiber Systems Dense Wavelength Division Multiplexing (DWDM) Alpina Kulkarni Optical Communications (EE566) Dr. Paolo Liu Electrical UB."— Presentation transcript:

1 Fiber Systems Dense Wavelength Division Multiplexing (DWDM) Alpina Kulkarni Optical Communications (EE566) Dr. Paolo Liu Electrical UB

2 Brief Overview ► Problems with increasing network demands ► Solutions proposed & their limitations ► Evolution of DWDM ► Technical details ► Drawbacks ► Ongoing Research ► Conclusion

3 Growing Network Usage Patterns ► Issues  Exponential  Exponential increase in user demand for bandwidth ► Doubling ► Doubling of bandwidth requirement every 6-9 months  Consistency  Consistency in quality of services provided  Keeping  Keeping the cost of solutions at bay ► Solutions  Increase  Increase channel capacity: TDM, WDM  Statistical  Statistical multiplexing of users: Multiple optical fibers

4 Another glimpse at the solutions ► WDM ► WDM (Wavelength Division Multiplexing)  Use  Use of optical fibers to achieve higher speeds  Utilize  Utilize wavelengths to multiplex users  Allow  Allow continuous channel allocation per user  Increases  Increases the effective bandwidth of existing fiber ► TDM ► TDM (Time Division Multiplexing)  Slotting  Slotting of channels simultaneous users  Increasing  Increasing bit rate to maximize utilization of given bandwidth

5 Limitations of current solutions ► WDM  Inefficient  Inefficient usage of full capacity of the optical fiber  Capability  Capability of carrying signals efficiently over short distances only ► Improvements in optical fibers and narrowband lasers  Birth of Dense WDM (DWDM) ► TDM  Dependency  Dependency of Mux-Demux on bit rate  Limitations  Limitations on bit rates ► how ► how fast can we go? (Decides how small the time slots can be)

6 Evolution of DWDM Late 1990’s 1996 DWDM Early 1990’s Narrowband WDM 1980’s Wideband WDM 16+ channels 100~200 GHz spacing 2~8 channels 200~400 GHz spacing 2 channels 1310nm, 1550nm 64+ channels 25~50 GHz spacing

7 What is DWDM? ► Definition  Dense wavelength division multiplexing (DWDM) is a fiber-optic transmission technique that employs light wavelengths to transmit data parallel-by-bit or serial-by-character

8 How does DWDM fair better? ► No O-E-O required ► Protocol & Bit Rate independence ► Increased overall capacity at much lower cost  Current fiber plant investment can be optimized by a factor of at least 32 ► Transparency  Physical layer architecture  supports both TDM and data formats such as ATM, Gigabit Ethernet, etc. ► Scalability  Utilize abundance of dark fibers in metropolitan areas and enterprise networks

9 Capacity Expansion

10 Basic Components & Operation ► Transmitting Side  Lasers with precise stable wavelengths  Optical Multiplexers ► On the Link  Optical fiber  Optical amplifiers ► Receiving Side  Photo detectors  Optical Demultiplexers ► Optical add/drop multiplexers

11 Optical Amplifier ► Eliminates O-E-O conversions ► More effective than electronic repeaters ► Isolator prevents reflection ► Light at 980nm or 1480nm is injected via the pump laser ► Gains ~ 30dB; Output Power ~ 17dB

12 Drawbacks ► Dispersion  Chromatic dispersion  Polarization mode dispersion ► Attenuation  Intrinsic: Scattering, Absorption, etc.  Extrinsic: Manufacturing Stress, Environment, etc. ► Four wave mixing  Non-linear nature of refractive index of optical fiber  Limits channel capacity of the DWDM System

13 Ongoing Developments ► Nortel Networks  Metro DWDM  OPTera Long Haul 5000 Optical Line System ► Cisco Systems  ONS Metro DWDM Solution ► Lucent Technologies  LambdaXtreme Transport  WaveStar OLS 1.6T ► Agility Communications & UC Santa Barbara  Tunable Lasers used for multiple wavelengths

14 Conclusion ► Robust and simple design ► Works entirely in the Optical domain ► Multiplies the capacity of the network many fold ► Cheap Components ► Handles the present BW demand cost effectively ► Maximum utilization of untapped resources ► Best suited for long-haul networks

15 References [1] Introducing DWDM [2] Fundamentals of DWDM Technology [3] Dense Wavelength Division Multiplexing (DWDM) [4] Dense Wavelength Division Multiplexing (DWDM) Testing [5] “Fiber-Optic Communications Technology” by D.K. Mynbaev, L.L. Scheiner, Pearson Education Asia, 2001 edition [6] “Dense wave nets' future is cloudy” by Chappell Brown, EETimes [7] Cisco Systems de09186a bb.html de09186a bb.html de09186a bb.html [8] Lucent Technologies LOCL+1,00.html LOCL+1,00.html [9] Nortel Networks: “OPTera Long Haul” & “Metro DWDM” (http://www.nortelnetworks.com/products/01/optera/long_haul/dwdm/) & (http://www.nortelnetworks.com/products/library/collateral/ pdf) [10] Agility Communications

16


Download ppt "Fiber Systems Dense Wavelength Division Multiplexing (DWDM) Alpina Kulkarni Optical Communications (EE566) Dr. Paolo Liu Electrical UB."

Similar presentations


Ads by Google