DWDM Transmission System.pptx

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.
lN
l2
l1
lN
l2
l1
lN
l2
l1
OMU ODU
OA

 The capacity expansion over TDM is more and more
close to the limitation the technology can afford;
 The high chromatic dispersion of laid G.652 optical
fiber restricts the transmission of systems over
10Gbit/s;
 The fast development of optical devices, esp. the
large scale commercialization of EDFA, brought
quick use of DWDM.
 From both technical and economic aspects, DWDM
is the most cost-effective capacity expansion
technology at present.
3
DWDM Background

 DWDM: Dense Wavelength Division
Multiplexing
 The wavelength division multiplexing
(WDM) multiplexes several or dozens of
optical signals with different wavelength
and transmits them in a same fiber
 Each optical path carries an SDH or other
signal.
4
DWDM

Basic Theory
power（dBm)
1530 - 1560nm wavelength λ
wavelength interval ：0.8～2nm

6
DWDM Structure
Optical
Repeater 1
┇
Input
Channel 1
Channel N
Channel 1
Channel N
λ1
λn
Optical
Repeater n
Optical
Multiplexer
BA LA PA
Optical
Demultiplexer
λ1
λn
Receiving
1
┇
Receiving
n
λs λs λs λs
Optical
Monitoring
Channel
R/T
Optical Monitoring
Channel Transmitter
Optical Monitoring
Channel Receiver
Output
Network
Management
System
Optical Transmitter Optical Trunk Amplification Optical Receiver

 Super-large capacity transmission
 Saving the fiber resources
 Transparent transmission of each path and
smooth scaling and expansion
 Super-long distance transmission based
on EDFA technology
 No special requirement on fiber chromatic
dispersion
 Basis of future optical network
7
DWDM Characteristics

 Everything over DWDM
8
DWDM’s Position in Network
IP
ATM
SDH
DWDM
Optical Fiber Physical Layer
Open Optical Interface
SDH ATM IP Other
s

9
DWDM Evolution
OADM.
3. Variable
Wavelength
OADM for
ring
network
4. Optical
network
with OXC
OTM OTM
1. DWDM P2P
Transmission
System
OTM OTM
OADM.
2. Fixed Wavelength
OADM for wavelength
adding/dropping

 Integrated and Open DWDM System
 Working Wavelength
 Main Optical Parameter
Quality and Process-Quality Circle
P_0010
DWDM Technical Specifications

P_0011
Integrated System & Open System
Integrated
O
M
U
G.692
Open
O
T
U
G.692
155MSDH
622MSDH
2.5G SDH
10G SDH
PDH
IP
ATM
155MSDH
622MSDH
2.5G SDH
10G SDH
PDH
IP
ATM
OTU: Optical Transponder Unit
OMU: Optical Multiplexing Unit

 DWDM Operating wavelength:
C - band & L - band
 C - band coverage: 1528-1561nm
 L - band coverage: 1577-1603nm
 As G.692 required, the channel distance is an
integral multiple of 100GHZ (about 0.8nm).
12
DWDM Operating Wavelength

 Rated frequency difference between two
adjacent multiplexer channels
 As G.692 required, the channel distance is
an integral multiple of 100GHZ.
13
Channel Distance

 Working wavelength range: C band (1530 nm ~ 1565 nm)
 Frequency range: 192.1 THz ~ 196.0 THz
 Channel interval: 100 GHz
 Central frequency offset: ±20 GHz (at rate lower than 2.5
Gbit/s); ±12.5 GHz (at rate 10 Gbit/s)
P_0014
Working Wavelength of DWDM System
8/16/32/40-wavelength system

P_0015
Wavelength Allocation of 40CH/100GHz Interval

P_0016
Wavelength Allocation of 40CH/100GHz Interval

 Light source
 Multiplexing/Demultiplexing
 Optical amplification
 Optical add/drop multiplexing
 Optical path monitoring
17
DWDM Key Technologies

 Detection, Control and Management are the
basic requirement of all the network operations
 To ensure effective management over the WDM
system the monitoring system is designed
separately from working channels and devices
 Used to transmit the NE management and
supervision information
18
Optical Supervision Technology

 Fault alarm
 Fault Location
 Quality parameter supervision in the operation
 Control over backup line upon line interruption
 EDFA supervision
P_0019
Function of OSC

 It can’t restrict the optical wavelength s of the pump light
source in OA
 It can’t restrict the transmission distance between two
line amplifiers
 It can’t restrict the services on future 1310nm
wavelength
 It should be Available upon failure of line amplifier
 OSC transmission is bidirectional to ensure the
supervision information can be received by the line
terminal when one fiber is broken
 OSC transmission segment can be dropped on each OA
relay station and system office station and added with
new supervision signals
20
Requirements of OSC

P_0021
Optical Supervision Control (OSC)
OSC OSC OSC OSC
OMU OBA OLA OLA OPA OMU
ODU OPA OLA OLA OBA OMU

 Monitoring Wavelength: 1510nm
 Signal speed : 2.048Mb/s
 Receiving sensitivity : -48dbm
 Transmission power : 0 ~ -7 dbm
OSC Parameters
22

P_0023
Overview of Protection in DWDM
System

 OCH - Optical Channel layer: support the transmission of single-wavelength
signals in DWDM system
 OMS - Optical Multiplex Section layer: support the transmission of multiplexed
signal
 OTS - Optical Transmission Section layer: transmit optical signals over optical
cables
 OAC - Optical Access layer: support the access of various client signals
P_0024
Hierarchical Architecture of DWDM System
G.692
...
OTU
OTU
OTU
OTU
Mux OBA OLA OPA
De
Mux
...
OTU
OTU
OTU
OTU
OTM OTM
OLA
TX1
TX2
TX3
TXn
RX1
RX2
RX3
RXn
OTS OTS
OMS
OCH
OAC OAC
OSC (T)
OSC
(R)
OSC (R/T)
1
l
...
...
2
l
3
l
n
l
1
l
2
l
3
l
n
l

 1+1 Protection
 The optical signals are simultaneously transmitted on
working and protection lines
 At received side selectively connects with the line with
better signal quality
 Link 1+1 protection
 Ring 1+1 protection
 1: N Protection
25
Protection of DWDM System

P_0026
1+1 protection OCH

P_0027
1+1 protection OCH

 Non-redundant Path 1+1 Protection:
 Advantage: Less OTU card, Low cost
 Disadvantage: LOF, SD in the path and OTU
card fail cannot activate switching
 Only LOS can activate switching
 Redundant Path 1+1 Protection:
 Advantage: LOS, LOF, SD in the path and
OTU card can activate switching
 Disadvantage: More OTU card, High cost
P_0028
Comparison

P_0029
Multiplex Section 1+1 Protection

P_0030
1+1 protection OMS
O
M
D
O
P
O
P
Direction A
line 1
l
O
D
U
O
D
U
O
M
U
OTU
OTU
OTU
OTU
l
l
ln
l
OTU
OTU
OTU
OTU
l
l
ln
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
l
l
l
ln
l
l
l
ln
Direction A
line 2
Direction B
line 1
Direction B
line 2
OBA
OBA
OPA
OPA
Line 1 is the working path Line 2 is the protecting path

 The protection channel and the working channel reaches
the receiving end through different routes
P_0031
Ring 1+1 protection
D
B
C A
Protection
Channel
Working
Channel

P_0032
Ring 1+1 protection of OCH
O
M
U
O
P
OTU
OTU
O
D
U
O
M
U
O
D
U
ODU
OMU
ODU
OMU
O
P
OTU
OTU
Working Channel
Protection Channel
Site A Site B

 In 1:N protection changeover, N multiplex working lines share
one protection line
 The protection function monitors and judges the received
signal status
P_0033
1:N Protection Principle
Protection Line
Working Line 1
Working Line 2
Working Line 3
Protection Line
Working Line 1
Working Line 2
Working Line 3
Service can be
transmitted

 Up on deterioration or failure of service signals on the
working line, changeover the service to the protection line
 When multiple lines of services are faulty at the same time,
the service in high priority will take priority of protection
P_0034
1:N Protection Principle
Protection Line
Working Line 1
Working Line 2
Working Line 3
Protection Line
Working Line 1
Working Line 2
Working Line 3
This Service is
discarded
Changeover
Protocol

35
1:N Protection on Multiplexing Layer
OMU OLA
。
ODU
。
Rx11
Rx12
Rx1m
Tx11
Tx12
Tx1m
WDM Working System
1
OMU
。
ODU
。
Rx21
Rx22
Rx2m
Tx21
Tx22
Tx2m
WDM Working System
2
OMU
。
ODU
。
Rxn1
Rn12
Rxnm
Txn1
Txn2
Txnm
WDM Working System
n
OMU
。
ODU
。
Rxp1
Rxp2
Rxpm
Txp1
Txp2
Txpm
WDM Protection System 1
。
。
。
。
OLA
OLA
OLA
1:N protection on
Multiplexing layer

1+1 protection
 Protection line is special and
can’t be shared with other
working lines
 Signaling support isn’t
required
 Easily implemented
 It can be used in any
network structure
 Its Bandwidth utilization ratio
is low and cost is high
Features of 1+1 and 1:N protection
P_00
36
1:N protection
 Protection line is shared by
multiple working lines
 Signaling support is
required
 Relatively complicated
implementation process
 It can be used in ring
network structure
 Its Bandwidth utilization
ratio is high but protection
reliability is low

37
DWDM Signal Flow
Line Amplifier
Terminal
BA
OMU
EDFA Power
Amplifier
O
M
U
EDFA
Preamplifier
R
ODU
OTU
2
S2
l2
OTU
n-1
ln-1
OTU
1
S1
l1
OTU
n
Sn
ln
Sn-1
OSC
RX/TX
O
D
U
SD1
SD1
SDn-1
SDn
R1
R2
Rn-1
Rn
PA
OMU
ODU
Optical
Monitoring
Channel
EDFA Line
Amplifier
LA
ODU
OMU
LA
OSC RX/TX
MPI-S
R'
MPI-R S'
OSC RX/TX
OADM
G.652
Fiber
MPI-S
R'
MPI-R S'
OM
U
OD
U
OADM
O
R
O
R
O
M
U
OD
U
OADM
O
R
O
R
BA
OMU
O
M
U
R
ODU
OSC
RX/TX
O
D
U
PA
Terminal
SD1
SD1
SDn-1
SDn
R1
R2
Rn-1
Rn
OTU
2
S2
l2
OTU
n-1
ln-1
OTU
1
S1
l1
OTU
n
Sn
ln
Sn-1
EDFA Line
Amplifier
EDFA
Preamplifier
EDFA Power
Amplifier
G.652
Fiber
Optical
Monitoring
Channel
Optical
Monitoring
Channel Optical
Monitoring
Channel
OR: Optical Repeater

 Uses ring topology
 B/s to protect services.
 One link for working other for protection.
 Optical fiber is the medium for
communication
P_0038
WR DWDM TOPOLOGY

P_0039

P_0040
GENERAL GATEWAY

ABOUT FIVE GATEWAYS ARE THERE
1. BOLE(FINFINNEE)---BR
2. MEKELLE---BR
3. DIRE DAWA---BR
4. SHASHAMMANNE---BR
5. BAHIR DAR---BR
ALL NETWORKED TO EACH OTHER BY
MEANS OF MESH.
P_0041
ETHIOPIAN NETWORK GATEWAY

WR(NEKEMTE) HAS ABOUT FIVE BB LINKS
1) ONE BY MW FROM BAKO
2) ONE BY DWDM FROM BAKO
3) THREE BY OTN i.e.
A. FROM BAKO
B. FROM GIDA
C. FROM BEDELE
P_0042
WR BB LINKS

BR(GW)
TXN
CR
TXN
ER(T-160)
TXN
T-64(SWITCH/AGG)
P_0043
NETWORK STRUCTURE

DWDM Transmission System.pptx

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