The paper is explain in detail about cwdm

1. TRANSMISSION SYSTEMS
1.WDM
2.What is CWDM?
3. CWDM Features
4.WORKING PRINCIPLE OF CWDM
5.Node Control Processor-NCP Board
6. CWDM TOPOLOGY
7. TROUBLE-SHOOTING
8. CWDM APPLICATIONS

2. 1.WDM
FIBER
 Fiber optics, or optical fiber, refers to the medium and the technology
associated with the transmission of information as light pulses along a glass or
plastic strand or fiber.
 In fiber-optic communications, wavelength-division multiplexing (WDM) is a
technology which multiplexes a number of optical carrier signals onto a
single optical fiber by using different wavelengths (i.e., colors) of laser light.
 This technique enables bidirectional(TX/RX) communications over one
strand of fiber, as well as multiplication of capacity.

3. Cont’d…
TWO TYPES OF WDM:
1. CWDM (Course wavelength division multiplexing).
2. DWDM(Dense wavelength division multiplexing).

4. 2.What is CWDM?
Course wavelength division multiplexing (CWDM) is a method of
combining multiple signal at various wavelengths(nm) for transmission
along fiber optic cables.
WAVELENGTH
A wavelength is a measure of distance between two identical peaks (high
points) or troughs (low points) in a wave -- a repeating pattern of traveling
energy like light or sound.
• v is the speed of light
• f is frequency
• λ is wavelength
• The relation is λ= v / f

5. CWDM systems have channels at wavelengths spaced 20 nanometers (nm)
apart.
This allows the use of low-cost, uncooled lasers for CWDM.
In a typical CWDM system, laser emissions occur on eight channels at
eight defined wavelengths: 1611 nm, 1591 nm, 1571 nm, 1551 nm, 1531
nm, 1511 nm, 1491 nm, and 1471nm.
This is also Ethiopian standard.
But up to 18 different channels are allowed, with wavelengths ranging
down to 1271nm.
P1=1471
P2=1491
P3=1511
P4=1531
P5=1551
P6=1571
P7=1591
P8=1611

6. Operating Wavelength
Wavelength(SN) Central Wavelength(nm)
0 1311
1 1471
2 1491
3 1511
4 1531
5 1551
6 1571
7 1591
8 1611
For common fibers ,the ZXMP M600 usually employs
8+1 wavelength with the wavelength spacing of 20 nm.
8 Channels for service
1 Channel for supervision

7. Operating Wavelength
Wavelength(SN) Central Wavelengths(nm) Wavelength(SN) Central Wavelength(nm)
1 1471 10 1291
2 1491 11 1311
3 1511 12 1331
4 1531 13 1351
5 1551 14 1371
6 1571 15 1391
7 1591 16 1411
8 1611 17 1431
9 1271 18 1351
For low water peak fibers the ZXMP M600 usually employs 18
wavelengths with the wavelength spacing of 20 nm.
 17 channels for service
 1 channel for supervision

8. I) Rich service access type:
• Multi-rate services access
• Continuous-rate services access (10 Mbit/s-
2.7 Gbit/s).
• Small granular/small particles service
convergence.
3.CWDM Features

9. II) Transmission Distance
• Transmission distance becomes one of the important technical index of
CWDM system.
• For a 8-λ point to point CWDM network, the optical fiber line
attenuation budget can reach 22.5dB (Distance: 75km @ 0.3dB/km)
• For a 8-λand 9-node ring CWDM network, the optical fiber line
attenuation budget for the whole ring can reach 18dB (perimeter:
60km @ 0.3dB/km)
• For longer transmission distance than the above, the regenerators be
used.
• Signal regeneration is signal processing that restores a signal,
recovering its original characteristics.

10. III) Transparent Transmission
• Transparent transmission is very essential for the various services used
in MAN.
• No cross connection simplifies the equipment and enhances the privacy
of the services.
transparent transmission

11. IV. Flexible and Convenient
• Support replaceable SFP optical modules
• Support mixed plug and hot plug of boards in CWU, and CWE chassis
except the PCW and NCP board.
• Support the front installation and hot plug of fans in the chassis.

12. V. Reliability
• Powerful protection capability (1+1 Path protection)
• Power supply card 1+1 backup and dual power supply modules
Receive one
Send
Together Send
Together

13. 4.WORKING PRINCIPLE OF CWDM
We can divide CWDM into two:
1.CWE
2.CWU
1.CWE has the following elements :
i. OPTICAL MUX/DEMUX (OMD) card.
ii. Line to cwu which carries all wavelengths i.e λ1-λ8
in both direction.
iii. ETMP card.

14. OPTICAL MUX/DEMUX(OMD )
OMD5-1US 1471/1491/1511/1531 1310
OMD4-5U 1551/1571/1591/1611
 OMD board is used to implement the multiplexing and demultiplexing of wavelengths.
 ZXMP M600 provides OMD boards for 8-channel or 18-channel systems.
 OMD5-1/OMD4-5 board adopts the single-fiber unidirectional transmission
mode.
 By combining OMD5-1 and OMD4-5, the multiplexing/demultiplexing of 8+1
wavelengths can be implemented, where +1 indicates 1310nm wavelength and
bears OSC supervision signals.
 Provides an upgrade interface

15. Indoor CWE panel

16. OPERATING PRINCIPLE OF OMD
1471/O
1471/I
1491/O
1491/I
1511/O
1511/I
1531/O
1531/I
LINE/I
LINE/O
1551/O
1551/I
1571/O
1571/I
1591/O
1591/I
1611/O
1611/I
OMD4-5U
OMD4-1US
LINE/I LINE/O
UPGR/O UPGR/I
1311/O
1311/I
Optical
signals on
east line
1471/I
1471/O
1491/I
1491/O
1511/I
1511/O
1531/I
1531/O
LINE/I
1551/I
1551/O
1571/I
1571/O
1591/I
1591/O
1611/I
1611/O
OMD4-5U
OMD4-1US
LINE/I LINE/O
UPGR/O UPGR/I
LINE/O
ETMg
1471nm
L2T
L2R L1T
L1R
ETMg
1491nm
L2T
L2R L1T
L1R
ETMg
1511nm
L2T
L2R L1T
L1R
ETMg
1531nm
L2T
L2R L1T
L1R
ETMg
1551nm
L2T
L2R L1T
L1R
ETMg
1571nm
L2T
L2R L1T
L1R
ETMg
1591nm
L2T
L2R L1T
L1R
ETMg
1611nm
L2T
L2R L1T
L1R
NCP
NCP
1311/I
1311/O
Optical
signals on
west line

17. Cont’d
Remark：Considering the convenience for
maintenance，the maximum amount of the
ETM boards which we install at the upper
CWE in the ring is 4，and then we install
the ETM boards at the below CWE from
λ5(1551).

18. 2.CWU
It is outdoor site CWU panel.
e.g λ1, λ2, λ3, λ4……
We can say it MSAG(MULTI SERVICE ACCESS GATEWAY)
1CWU=1MSAG
Has the following parts.
i. ODF(OPTICAL DISTRIBUTION FRAME)
ii. OAD (OPTICAL ADD/DROP) BOARD
iii. ETMP BOARD
iv. NCP(NETWORK CONTROL PROCESSER)

19. I. Optical Add/Drop (OAD) Board
 Functions:
 Optical Add/Drop (OAD) board implements the
adding/dropping of specific wavelengths in CWDM
system.
 Three wavelengths can be added or dropped at most.
When more than three wavelengths are required to be
added or dropped, OAD board can be cascaded with
OMD board to implement the adding/dropping of them.
 Classification:
 Three kinds of OAD boards are provided (OAD1,
OAD2 and OAD3) to add/drop 1 to 3 wavelengths
respectively.

20. Operating Principle of OAD Board
OAD Unit
Circuit Monitoring Unit
Aline/I
Aline/O
Bline/O
Bline/I
B_ADi
A_ADi i=1，2，3

21. 1. Running indicator (bi-color)
2. Line optical interface in A direction (A-line)
3. Channel optical interface in A/B direction (A-ADn/B_ADn, n=1, 2, 3)
4. Line optical interface in B direction (B-line)
5. Laser warning sign
Front Panel of OAD Card

22. Front Panel of ETM Board
1. Switching indicator
2. Client optical interface indicators
3. Client optical interfaces
4. Line optical interfaces
5. Line optical interface indicators
6. ETH electrical interfaces
7. Laser warning sign

23. ETM Board
 Ethernet Multiplexer (ETM) board
multiplexes two channels of GE
optical signals and one channel of
FE Ethernet electrical signals or
one channel of ETH signals
(supervisory channel) at tributary
side into optical signals with
specific wavelength at aggregate
side in compliance with ITU-T
G.694.2. The aggregate signal
adopts 8B/10B encoding pattern
and its rate is 2.66 Gbit/s. In the
opposite direction, demultiplexing
is implemented
 Eight types of ETM board are
available, as shown in the right
table.
Board Type Description
ETMb
Single-path bidirectional terminal ETM board
without protection function
Its aggregate optical interface uses an
unpluggable optical module.
ETMs
Single-path bidirectional terminal ETM board
without protection function
Its aggregate optical interface uses a
pluggable SFP optical module.
ETMp
Single-path bidirectional terminal ETM board
with protection function
ETMg
Single-path bidirectional regenerator ETM
board without protection function
ETMbf
Single-path bidirectional terminal ETM board
without protection function; aggregate adopts
MSA28 (L1); ETH port is used to access FE
services.
ETMsf
Single-path unidirectional terminal ETM board
without protection function; aggregate adopts
SFP (L2); ETH port is used to access FE
services.
ETMpf
Single-path bidirectional terminal ETM board;
aggregate adopts MSA28 (L1)+SFP (L2); ETH
port is used to access FE services.
ETMgf
Single-path bidirectional regenerator ETM
board; aggregate adopts MSA28 (L1)+SFP (L2);
ETH port is used to access FE services.

24. ETMp ports correspondence
C1R
C2R
C1T
C2T
L1T
L1R
L2T
L2R

25. 5.Node Control Processor-NCP Board
Functions:
• Node Control Processor (NCP) board is a Network
Element (NE) control processor to perform all functions of
NE supervision subsystem:
– Collect and process the alarm and performance information, and
then report them to the network Element Management System
(EMS).
– Capable of saving the configuration data, thus NCP board can
work independently without EMS after setting initial configuration.
– Provide management to multiple subracks.
– Support online download of board programs.

26. ZXMP M600 Network Management and
Supervision Channel
• ZXONM E300 is used as NMS.
• Supervision channel adopts two
wavelengths: 1310nm and 1510nm.

27. NCP Board Panel
1. Dichromatic Indicator
2. RS232 Interface
3. ALM Interface
4. ETHn Interface
5. Ethn Indicator
6. OSC Optical Interface
7. Reset Button
8. Laser Warning Sign

28. 6.CWDM TOPOLOGY
It is ring topology and chain topology.
We use ring topology because when the signal
coming from working direction fails the signal
from protection side will work automatically.
This results as the customers services doesn’t
affected by absence of the system.

29. CONT’D….

30. 7.Trouble-shooting
1. The physical layer first, and then the configuration
Such as：checking the fiber cable and SFP first, then checking the digital
performance at the ports and the OP configuration
2.The external connection first, and then the internal connection
Such as：checking the client ports which were connected with the AG or
IP equipment, and then checking the line side ports(OCH) or OAD/OMD
boards.

31. The step in trouble-shooting
Firstly, master the service flow route:
ETMp_C1R/TETMp_L1R/TOAD_A_AD2_I/OOAD_Aline_I/O|OMD4-
1_Line_I/OOMD4-1_XXXX_I/OETMp_L1R/TETMp_C1R/T
Green for CWU ports,
Blue for CWE ports.
Detailed step：1) Query the alarm at ETMp_C1R/T, ETMp_C1R/T；
Such as：① no input power, input power weak, LOS , we can clean or
change the fiber or the SFP, checking the connection between transmission and AG or IP；
2) Query the alarm at ETMp_L1R/T、ETMp_L1R/T；check the ports and fiber.
Such as：①ETMp_L1R with the alarm “no input power”, “input power weak”, we need to
check all the corresponding ports and fibers in the service flow route(show as red line)
②ETMp_L1R with “no input power”, “input power weak”，the procedure same as the
alarm in ETMp_L1R

32. CONT’D

33. CONT’D
3 .After the checking about the physical layer, the next is checking the configuration and
the digital performance at the ports and the OP configuration.
（I）Checking the receive packet over ETMp_C1R,ETMp_C1R to make that M600 get the
signal from AG and IP normally.
（II) Checking the send packet over ETMp_C1T,ETMp_C1T, the route as shown in the
following figure：
 The trouble reason over ETMp_L1T could be one of the following：
ETMp board fail in CWE；
Nearend loop at ETMp in CWE;
 Over OAD, Line_O, Aline_I, A_AD2_O ,the trouble reason could be one of the following：
fiber cross connection
SFP fail
huge attenuation；
 The trouble reason over ETMp_L1R could be one of the following：
ETMp board fail in CWU；
Nearend loop at ETMp in CWU;
The fiber cross connection over L1R,L1T；

34. 8.CWDM APPLICATIONS
Adding CWDM in the optical transport is:-
 Simple and cost-effective solution for fiber
exhaust relief.
 New services can be added over a single
existing optical fiber, without interrupting service
to existing customers
 From CWDM a customer can get Voice and
data/internet.
e.g. Fixed line telephone
Internet service

35. END!!!!
THANK YOU!!!