Transcript No Slide Title

ECE-641
FIBER OPTICS AND OPTICAL COMMUNICATIONS
WINTER 2003
CLASS PROJECT
COMPARATIVE STUDY ON CWDM AND DWDM
PRESENTER: FREDRICK KETANGENYI
INSTRUCTOR: DR. TIM KURZWEIG
7/17/2015
ECE 641 PROJECT: STUDY ON
CWDM AND DWDM
PRESENTATION
OUTLINE
1:
-
OVERVIEW
2:
-
MEANING OF WDM.
3:
-
IMPLEMENTATION OF DWDM.
4:
-
IMPLEMENTATION OF CWDM.
5:
-
DIFFERENCES BETWEEN CWDM AND DWDM.
6:
-
CONCLUSION.
7/17/2015
ECE 641 PROJECT: STUDY ON
CWDM AND DWDM
1:
PAPER OVERVIEW
THIS PAPER BRINGS TO LIGHT ONE OF THE MANY METHODS AVAILABLE
IN THE QUEST TO PUSH MORE DATA THROUGH EXISTING SIGNAL
TRANSMISSION LINES.
THIS IS WAVELENGTH DIVISION MULTIPLEXING - WDM, WHICH IN ESSENCE
IS ANALOGOUS TO FDM(frequency division multiplexing) SINCE EVERY
FREQUENCY CORRESPONDS TO A DIFFERENT WAVELENGTH.
DISCUSSION IS ON THE CHARACTERISTICS OF DWDM AND CWDM, WHICH
HAVE BEEN DERIVED FROM WDM , AND FACTORS BEHIND THEIR
DIFFERENT APPLICATIONS IN OPTICAL NETWORKS.
7/17/2015
ECE 641 PROJECT: STUDY ON
CWDM AND DWDM
2:
WHAT IS WDM ?
IT IS A MULTIPLEXING TECHNIQUE THAT ENABLES MANY OPTICAL SIGNALS,
EACH OF DEFFERENT WAVELENGTH TO PROPAGATE DOWN A SINGLE FIBER.
WDM OVERLAYS SIGNALS ONTO A SINGLE MODE FIBER OPERATING ON
WAVELENGTH CENTERED AT 1550nm. THE WAVELENGTHS ARE WIDE SPREAD WITH
2 TO 16 CHANNELS IN NORMAL DEPLOYMENTS. DISTANCE IS LIMITED TO 100km.
FILTERS ARE USED IN MULTIPLEXING(add) AND DEMULTIPLEXING(drop) OF
OPTICAL SIGNALS.
FIGURE-1 BELOW IS A SCHEMATIC OF A BASIC WDM SYSTEM WITH .
Fig.-1
Wavelength Multiplexing by a filter.
7/17/2015
ECE 641 PROJECT: STUDY ON
CWDM AND DWDM
2-1:
COMPONENTS OF WDM
A BASIC WDM SYSTEM CONSISTS OF THE FOLLOWING COMPONENTS:
i) AN OPTICAL LASER(transmitter) .
ii) AN OPTICAL DETECTOR(receiver)
iii) OPTICAL FILTERS FOR MULTIPLEXING(add) AND DEMULTIPLEXING(drop)OADM.
iv) OPTICAL AMPLIFIER FOR DISTANCE EXTENSION.
OPTICAL LASER AND OPTICAL DETECTOR ARE INTEGRATED INTO ONE
TRANSCEIVER, THUS OPERATING AT THE SAME WAVELENGTH.
FIGURE-2 SHOWS THE COMPONENTS OF A WDM SYSTEM.
Fig.-2 : A WDM system.
7/17/2015
ECE 641 PROJECT: STUDY ON
CWDM AND DWDM
3:
IMPLEMENTATION OF WDM BY DWDM
DENSE-WDM IS THE SUMPERIMPOSITION ON A SINGLE FIBER, OF MANY OPTICAL
SIGNALS A DIFFERENT WAVELENGTHS(lambda), CLOSELY SPACED AT 0.8nm - 2nm.
DWDM DELIVERS DATA RATES OF UP TO 10Gbps(OC-192) OVER A FIBER, WITH
CURRENT SYTEMS SUPPORTING OVER 128lambdas. WINDOW OF OPERATION IS BETWEEN
1530nm and 1560nm,
COOLED LASERS ARE USED IN ORDER TO PREVENT WAVELENGTH DRIFTS THAT
WOULD EVENTUALLY CAUSE INTERFERENCE AMONG THE DENSELY PACKED
WAVELENGTHS.
A NON-ZERO DISPERSION SHIFTED FIBER CENTERED AT 1545nm IS USED AND OPTICAL
AMPLIFIERS AND REGENERATORS ARE USED ALONG THE ROUTE.
DWDM IS STANDARDISED BY ITU-T RECOMMENDATION G.694.1 FOR USE IN LONG
HAUL TRANSMISSION.
Figure-3 on the right depicts a pair
of mux/demux with ILAs
between the two ends.
Fig.-3
7/17/2015
ECE 641 PROJECT: STUDY ON
CWDM AND DWDM
4:
IMPLEMENTATION OF WDM BY CWDM
IN COURSE-WDM THE WAVELENGTHS ARE SPACED FARTHER APART WITH
CHANNEL SEPARATIONS OF 20nm BEING DEPLOYED.
UNCOOLED LASERS ARE USED AS SOURCE , THUS ALLOWING WAVELENGTHS TO
DRIFT WITHOUT FEAR OF INTERFERENCE. THE WIDE CHANNEL SEPARATION
PROVIDES THE LAXITY.
THE WAVELENGTH WINDOW IS EXTENDED TO BETWEEN 1270nm and 1610nm.
DATA RATES OF UP TO 2.5Gps WITH A TRANSMISSION DISTANCE LIMITED TO
ABOUT 31km. 18 DIFFERENT CHANNELS ARE SUPPORTED BY CWDM.
CWDM IS REGULATED BY ITU-T RECOMMENDATION G.694.2.
Figure-4 on the left shows an
8 channel CWDM system
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ECE 641 PROJECT: STUDY ON
CWDM AND DWDM
5:
DIFFERENCE BETWEEN CWDM AND DWDM
CWDM
DWDM
•
USES UNCOOLED LASERS FOR
SIGNAL LAUNCH.
•
USES THERMALLY CONTROLED(cooled)
LASERS FOR SIGNAL LAUNCH.
•
PACKS LESS WAVELENGTHS,
CURRENTLY UP TO 32.
•
PACKS MORE WAVELENGTHS PER
FIBER TRANSMISSION CHANNEL, UP TO
128.
•
MOSTLY PASSIVE COMPONENTS
ARE EMPLOYED, LIMITING ITS
APPLICATION TO ETHERNETWANs.
•
ACTIVE COMPONENTS ARE USED,
THUS CAN EXTEND DISTANCE FOR
LONG HAUL TRANSMISSION.
•
DATA RATES ARE LOWER, UP TO
2.5Gbps(OC-48).
•
DATA RATES ARE COMPARABLY
HIGHER TO THE ORDER OF 10Gbps(OC192)
•
WIDER WINDOW OF OPERATION,
1270nm TO 1610nm.
•
WINDOW OF OPERATION IS BETWEEN
1530nm AND 1560nm.
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ECE 641 PROJECT: STUDY ON
CWDM AND DWDM
6:
CONCLUSION
BOTH CWDM AND DWDM DELIVER MORE DATA RATE THAN THE BASIC
WDM.
HOWEVER, THESE TWO TECHIQUES HAVE DIFFERENT APPLICATIONS IN THE
OPTICAL NETWORK, MAINLY DUE TO THEIR DIFFERENCE IN IMPLEMENTATION.
THE DWDM IS PREFERRED FOR LONG HAUL TRANSMISSION SYSTEMS WHERE
AS CWDM IS MOSTLY PREFERRED FOR MAN/WAN IMPLEMENTATIONS.
THE REASONS FOR THIS CLASSIFICATION IS BASED ON TWO REASONS:
i) ECONOMIC AND BUDGETARY- IT IS NOT FEASIBLE TO DEPLOY CWDM FOR
LONG HAUL SINCE THIS WILL REQUIRE LOTS OF ACTIVE COMPONENTS ALONG
THE WAY JUST TO DELIVER A FEW NUMBER OF CHANNELS. ALSO UNCOOLED
FIBER IS CHEAPER COMPARED TO THERMAL CONTROLED FIBER USED FOR
DWDM. ON THE OTHER HAND, IT IS OF FEASIBLE TO DEPLOY DWDM FOE
LAONG HAUL.
ii) IMPELEMENTATION/TECHNOLOGY - THE USE OF UNCOOLED LASERS
MAKES CWDM IMPOSSIBLE FOR LONG HAUL SINCE THE WIDE SEPARATION
BETWEEN THE SIGNALS WILL EVENTUALLY CAUSE INTERFERENCE.
7/17/2015
ECE 641 PROJECT: STUDY ON
CWDM AND DWDM