Multiplexing

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Multiplexing

Group members
Harpreet kaur
Amandeep kaur
Sunnia kataria
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What is Multiplexing It is the process of
sending signals from two or more different
sources simultaneously over a single
communication channel. Multiplexing is
done by using a device called multiplexer(MUX)
that combines n input lines to gernate one output
line i.e (many to one).Therefore multiplexer
(MUX) has serval inputs one output.
At the receiving end , a device demultiplexer
(DEMUX) is used that separtes signal into its
components.so DEMUX has one input ans seval
outputs.
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• Types of Multiplexing
• Frequency Division Multiplexing (FDM)
• Wave Division Multiplexing (WDM)
• Time Division Multiplexing (TDM)

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• Frequency Division Multiplexing
• It is analog technique.
• In FDM, signals of different frequencies are
  combined into a single composite signal and is
  transmitted on single link.
• FDM requires that the bandwidth of a link should
  be greater than the combined bandwidths of
  various signals to be transmitted.
• Thus each signal having different frequency from
  a particular logical channel on the link and
  follow this channel only.
• These channels are then separeted by the strips
  of unused bandwidth called gurad band.These gurad
  bands band prevent the signals from overlapping.

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• Frequency Division Multiplexing
• In FDM signals to be transmitted must be analog
  signals. Thus digital signals need to be
  converted to analog form, if they are to use FDM.

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• Applications of FDM
• FDM is used for FM AM radio broadcasting. Each
  AM FM radio stations uses a different carries
  frequency .
• FDM is used in television broadcasting.
• First generation cellular telephone also uses
  FDM.

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• Wave Division Multiplexing
• WDM is the analog multiplexing technique.WDM is
  conceptually similar to FDM, in sense that it
  combines different signals of different signals
  of different frequencies into single composite
  signal and transmit it on a single link.
• In WDM the different signals are optical or
  light signals that are transmitted through
  optical fiber.Wavelength goes up down and
  vice-verse.
• In WDM various waves from different sources are
  combined to form composite light signal that is
  transmitted across the channels to the different
  receiver.

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• Wave Division Multiplexing
• At the receiver side, this composite light
  signal is broken into different light waves by
  demultiplexer.
• This combines and splitting of light waves is
  not by using a prism.
• One prism is used at the sender side to perform
  multiplexing and another prism is used at
  receiver side that perform demultiplexing.
• The basic principal behind the usage of prism is
  that,the prism bends a beam of light based on the
  angle of incidence and the frequency of light
  wave.

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• Applications of WDM
• WDM is used in SONET(Synchronous Optical
  Network).It makes use of multiple optical fiber
  lines which are multiplexed demultiplexed.

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• Time Division Multiplexing
• TDM is a digital multiplexing technique.
• In TDM, the channels is not divided on the basis
  of frequency but on the basic of time.
• Total time available in the channel is divided
  between serveral users.
• Each time is allotted a particular a time
  interval called time slot during which the data
  is transmitted by that user.
• Each sending device takes control of entire
  bandwidth .

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• Time Division Multiplexing
• There are two types of TDM
• Synchronous TDM Asynchronous TDM

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• Synchronous TDM
• Multiplexer allots the same time slot to each
  device at all time either device having data or
  not.
• If there are n input lines then there are n
  slots in one frame. Number of slots No of input
  lines.
• Synchronous TDM does not give guarantee that
  full capacity of link is used .
• The no of time slot in a frame is always based
  on no of input devices .
• The time slots are fixed and predefined.

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• Asynchronous TDM
• It is also known as STATISTICAL TDM.
• Multiplexer does not allots same time slot to
  each device at all time . Time slots are flexible
  and not fixed.
• If there are n input lines then there are m
  slots perform. m is less than n.
• Asynchronous TDM give guarantee that full
  capacity of link is used .
• The no of time slot in a frame is always based
  on statistical analysis of no of input devices.
• The time slots are not fixed and predefined.

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• Reference
• Charanjeet singh
• 
  (kalyani Publisher)