Multiplexing, how they work ?

1. MULTIPLEXING
Submitted by – Rama Chandra Dey
Roll Number - CS/08/22
Class - 1st Year MCA
Guided by – Dr. Minati Mishra
Department Of Computer Science

2. CONTENT
 What is Multiplexing ?
 Why Multiplexing ?
 History of Multiplexing
 Concept of Multiplexing
 Advantages of Multiplexing
 Types of Multiplexing
Frequency Division Multiplexing
Wavelength Division Multiplexing
Time Division Multiplexing

3. MULTIPLEXING
 Multiplexing is a method of combining and transmitting several data
streams across a single media.
 It is the process in which multiple signals coming from multiple
sources are combined and transmitted over a single communication
or Physical line.
 The hardware device which is used for multiplexing is known as a
Multiplexer(MUX).
 Multiplexer combines ‘n’ input lines to generate a single output line.
It follows many to one i.e. n input line and one output line.
 Demultiplexer is a device that separates multiple signals into its
component signals. It follows one to many approach.

5. Why Multiplexing ?
 The transmission medium is used to send the signal from
sender to receiver. The medium can only have one signal at a
time.
 If there are multiple signals to share one medium, then the
medium must be divided in such a way that each signal is
given some portion of the bandwidth.
 If there are 10 signals and bandwidth of medium is 100 units,
then the 10 unit is shared by each signal.
 When multiple signals share the common medium, there is a
possibility of collision. Multiplexing concept is used to avoid
such collision.

6. History of Multiplexing
 Multiplexing originated in telegraphy in the early
1870s and is now widely used in communication.
 George Owen Squier developed the telephone
carrier multiplexing in 1910.

7. Concept Of Multiplexing
 The ‘n’ input lines are transmitted through a multiplexer
and multiplexer combines the signals to form a composite
signal.
 The composite signal is passed through a Demultiplexer
and demultiplexer separates a signal to component signals
and transfers them to their respective destinations.

8. Types of Multiplexing
Multiplexing
Frequency
Division
Multiplexing
Wavelength
Division
Multiplexing
Time Division
Multiplexing
Synchronous
TDM
Asynchronous
TDM

9. Frequency Division Multiplexing
 Frequency Division Multiplexing is an analogue technique
that divides the available bandwidth of a single transmission
medium into several channels.
 Modulation methods are used to convert the input signals
into frequency bands, which are then merged by a
multiplexer to produce a composite signal.
 Here, there are 3 devices which sends analogue signals to
the multiplexer through modulator with the help of
transmission media.
 By the multiplexer device, signals are combined to form
composite signals.
 The carriers which are used for modulating the signals are
known as Sub-carriers. They are represented as f1,f2,…fn.

10. Frequency Division Multiplexing
 With the help of Demultiplexer, the composite signals are
sub-divided into different frequency channels and allocate
them to different respected devices.
 This technique is widely used in Telecommunication
networks, Wireless Networks, FM radio etc.

11. Frequency Division Multiplexing
Advantages
 It is used for analogue signals.
 FDM process is very simple and
easy modulation as compared
to other multiplexing system.
 A large number of signals can
be sent through the FDM
simultaneously.
 It does not require any
synchronization between
sender and receiver.
Disadvantages
 FDM technique is used only when
low speed of channels are required.
 It suffers the problem of crosstalk.
 A large number of modulators are
required.
 It requires a high bandwidth
channel.

12. Wavelength Division Multiplexing
 Wavelength Division Multiplexing is similar to FDM except that the
optical signals are transmitted through the fibre optic cable.
 It is used to utilize the high data rate capability of fibre optic cable.
 Optical signals from different source are combined to form a wider
band of light with the help of multiplexer.
 At the receiving end, demultiplexer separates the signals to transmit
them to their respective destinations.
 Multiplexing and demultiplexing can be achieved by using a prism.
 Prism can perform a role of multiplexer by combining the various
optical signals to form a composite signal, and the composite signal
is transmitted through a fibre optical cable.
 Prism also perform a reverse operation i.e. demultiplexing the
signals.

14. Wavelength Division Multiplexing
Advantages
 With the aid of WDM, several
signals may be sent at the
same time.
 This method is less costly,
and system expansion is
simple.
 This method is highly secure.
 Because optical fibre is used
in WDM, optical components
are more dependable and
provide more bandwidth.
Disadvantages
 Because optical equipment is
used, the cost rises.
 Because of poor bandwidth
use, wavelength adjustment
might be challenging.
 This technique’s major issue
is scalability.