BASIC WDM OPTICAL
NETWORK
Dara Aulia Feryando
Telecommunication Engineering
Telkom University
2015
What is WDM ???
• WDM (Wavelength Division Multiplexing) is multiplex
technique used in optical network. It’s used to multipex
some of wavelength that come in optical network
• In WDM, one channel is used for only one wavelength like
FDM that only pass one frequency in one channel.
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WDM ARCHITECTURE
• Generally, WDM architecture is classified in two
categories :
1. Broadcast and select WDM network
2. Wavelength routed WDM network.
Broadcast and select WDM network
• It’s the architecture of WDM
network that have a simple
broadcast system
• Star topology is a popular
topology used in this
architecture. Another topology
in this network is bus topology.
How does Broadcast and select WDM
network work??
Different node transmit messages on different
wavelength simultaneously. The star coupler
combines all these messages and then
broadcasts the combined message to all the
nodes. A node selects a desired wavelength
to receive the desired message by tuning its
receiver to that wavelength.
Advantages and Disadvantages of
Broadcast and select WDM network
• Advantages:
Having a simple broadcast system
• Disadvantages:
They have limitations such as large number of wavelength are
required, there is no wavelength reuse in the network. they cannot
span long distances since the transmitted power is split among
various nodes and each node receives only a small fraction of the
transmitted power, which becomes smaller as the number of nodes
increases
Wavelength Routed WDM Network
• There are two main components : Routing node and access node.
• Routing node route the sent messages
• Access node has function as O-E-O converter
How does Routed WDM Network work??
A message is sent from one node to another node using a
wavelength continuous route called a light path. A light path
is an all-optical communication path between two nodes,
established by allocating the same wavelength throughout
the route of the transmitted data.
The Requirements of Light Path
• Wavelength continuity constraint:
The requirement that the same wavelength must be used
on all the links along the selected route
• Distinct wavelength assignment constraint :
Two light paths cannot be assigned the same wavelength
on any fiber.
Advantages and Disadvantages of
Broadcast and select WDM network
• Advantages:
A same wavelength can be used in other different link or we can say a
wavelength can be reused in this network.
• Disadvantages:
Inefficient utilization of wavelength channel, bandwidth loss caused by
the wavelength continuity constraint.
References
• Gond , Vitthal J. and Aditya Goel. “Performance Evaluation of
Wavelength Routed Optical Network with Wavelength Conversion”.
Journal of Telecommunication, vol.2,issue 1, April 2010
• Zheng, Jun and Hussein T. Mouftah. 2004. “Optical WDM Networks:
Concepts and Design Principles”.Institute of Electrical and Electronic
Engineers, Inc.
Thank You . . .