dwdm technology

1. DWDM, SDH
NETWORK
NOC

2. The DWDM technology is this kind of fiber
communication technology: Transmitting multiple
optical carriers with information (analog or digital) on
one fiber and expanding system only through
wavelength (channel) increase. It can combine
(multiplex) optical signals with different wavelengths
and then transmit them. After the transmission, it
can separate (de-multiplex) the combined optical
signals and then send them to different
communication terminals. In other words, it can
provide multiple virtual fiber channels on one
physical fiber.
DWDM

3. • An international standard for high-speed optical /
electrical telecommunication networks.
• A synchronous digital transport system with a built-
in
• management channel for remote management of
complex topologies.
• High transmission rates.
• Lower level signals embedded that are identified
from the higher level (much simpler Add & Drop)
• Optical standard.
• Can be introduced into existing networks.
SDH(SONET)

4. Both DWDM system and SDH system belong to the transmission
network layer. They are the transmission means established on the
fiber transport media
1. The SDH system implements multiplexing, cross-connection and
networking on the electrical channel layer. The WDM system
implements multiplexing, cross-connection and networking on the
optical domain
2. Multiplexing modes of DWDM and SDH for carrier signals
The SDH is the TDM system based on a single wavelength (one fiber
transmitting one wavelength channel). When the transmission rate
exceeds 10 Gbit/s, the system dispersion and other negative influences
will increase the difficulty of long-distance transmission.
The DWDM technology simultaneously transmits multiple optical
carrier signals of different wavelengths in the same fiber, fully utilizing
the bandwidth resources of fiber and increasing system transmission
capacity.
3. DWDM capable of transmitting different types of signals
At present, most customer-layer signals in the DWDM system are SDH
signals. But the wavelengths used in the DWDM system are mutually
separated and irrelated with the service signal formats, so each
wavelength can transmit the optical signals with totally different
features, for the sake of hybrid transmission of multiple kinds of signals.
Relationship between DWDM and SDH

5. VIETTEL PERU NETWORK

6. The quartz fiber has three low-loss windows: 860 nm, 1310 nm and 1550
nm, as shown in Fig 1.
C band (1530 nm ~ 1565 nm): It is often used as the working wavelength
area of the DWDM system under 40 waves (with band interval as 100
GHz), DWDM system under 80 waves (with band interval as 50 GHz) and
SDH system.
Operation Wavelength Range
0
0.5
1.0
1.5
2.0
2.5
3.0
800 1000 1200 1400 1600
Wavelength (nm)
Loss (dB/km)
~140THz
~50THz
OH- absorption peak
OH- absorption
peak
OH- absorption
peak
O E S C L

7. • Fully utilizing fiber bandwidth resources and featuring large
transmission capacity
• Super-long transmission distance
• Abundant service access types
• Saving fiber resource
• Smooth upgrading and expansion
• Standar G.655 (non-zero dispersion shifted SMF)
In the 1550 nm window, the absolute value of its dispersion is not zero
and within a certain range (ensuring smallest loss and small dispersion
in this window).
It is applicable to the high-rate and long-distance optical communication
system. In addition, non-zero dispersion suppresses the influence of
non-linear FWM over DWDM system. Therefore, this kind of fiber is
usually used in the DWDM system.
DWDM Features and Advantages

8. Based on multiplexing channel quantity and frequency interval of the
DWDM system, the working wavelengths of the systems below 40
wavelengths.
8/16/32/40-wavelength system
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)
Introduction to Working Wavelength Area

9.  The DWDM system multiplexes several or dozens of optical channel
signals with different nominal wavelengths to one fiber for
transmission, with each optical channel bearing one service signal.
 The basic structure of a unidirectional DWDM system is shown in Fig 2
Basic Structure of DWDM System
Receiver/transmitter of
optical supervision channel
 n
2
1
3
G.692
...
Optical
transponder
OM OBA OLA OPA
Receiver of optical
supervision channel
Transmitter of optical
supervision channel
OD
 n
3
2
1
...
Optical transmitter Optical receiver
Optical relay amplifier
TX1
TX2
TX3
TXn
RX1
RX2
RX3
RXn
Optical
transponder
Optical
transponder
Optical
transponder
Optical
transponder
Optical
transponder
Optical
transponder
Optical
transponder

12. SUMARY
OTN: Optical Transport Network
OUT: Optical Transponder Unit
WDM: Wavelength Division Multiplexing
OLA: Optical Line Amplifier
OPA: Optical Preamplifier Amplifier
OADM: Optical Add/Drop Multiplexer
EDFA: Erbium Doped Fiber Amplifier
DWDM: Dense Wavelength Division Multiplexing
SDH: Synchronous Digital Hierarchy
OBA: Optical Booster Amplifier