8 ? ???(Multiplexing)

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8 ? ???(Multiplexing)

• 8.1 Many to One/One to Many
• 8.2 Type of Multiplexing
• 8.3 Multiplexing Application Telephone system
• 8.4 ??

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???(Multiplexing)

• ???(Multiplexing)
• is the set of techniques that allows the
  simultaneous transmission of multiple signals
  across a single data link.

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???(Multiplexing)

• Multiplexing vs. No Multiplexing

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8.1 Many to One/One to Many

• ????(Multiplexer)
• transmission streams combine into a single
  stream(many to one)
• ?? ???(Demultiplexer)
• stream separates into its component
  transmission(one to many) and directs them to
  their intended receiving devices

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8.2 Types of Multiplexing

• Categories of Multiplexing

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Types of Multiplexing(contd)

• FDM(Frequency-Division Multiplexing)
• is an analog technique that can be applied
  when the bandwidth of a link is greater them the
  combined bandwidths of the signals to be
  transmitted

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Types of Multiplexing(contd)

• FDM process
• each telephone generates a signal of a similar
  frequency range
• these signal are modulated onto different carrier
  frequencies(f1, f2, f3)

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Types of Multiplexing(contd)

• FDM multiplexing process, time-domain

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Types of Multiplexing(contd)

• FDM multiplexing process, frequency-domain

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Types of Multiplexing(contd)

• Demultiplexing
• separates the individual signals twin their
  carries and passes them to the waiting receivers.

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Types of Multiplexing(contd)

• FDM demultiplexing process, time-domain

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Types of Multiplexing(contd)

• FDM demultiplexing, frequency-domain

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Types of Multiplexing(contd)

• Example Cable Television
• coaxial cable has a bandwidth of approximately
  500Mhz
• individual television channel require about 6Mhz
  of bandwidth for transmission
• can carry 83 channels theoretically

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Types of Multiplexing(contd)

• TDM(Time-Division Multiplexing)
• is a digital process that can be applied when
  the data rate capacity of the transmission medium
  is greater that the data rate required by the
  sending and receiving device

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Types of Multiplexing(contd)

• TDM

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Types of Multiplexing(contd)

• TDM can be implemented in two ways
• Synchronous TDM
• Asynchronous TDM

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Types of Multiplexing(contd)

• Synchronous TDM
• the multiplex allocates exactly the same time
  slot to each device at all times, whether or not
  a device has anything to transmit.

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Types of Multiplexing(contd)

• Frame
• Time slots are grouped into frame
• A frame consists of one complete cycle of time
  slots, including one or more slots dedicated to
  each sending device, plus framing bits.

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Types of Multiplexing(contd)

• Synchronous TDM

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Types of Multiplexing(contd)

• Interleaving
• switch moves from device to device at a
  constant rate and in a fixed order

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Types of Multiplexing(contd)

• Demultiplexer decomposes each frame by discarding
  the framing bits and extracting each character in
  turn
• Synchronous TDM, demultiplexing process

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Types of Multiplexing(contd)

• Framing bits
• allows the demultiplexer to synchronize with
  the incoming stream so that it can separate the
  time slots accurately
• (ex 01010101 .)

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Types of Multiplexing(contd)

• Synchronous TDM Example

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Types of Multiplexing(contd)

• Asynchronous TDM

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Types of Multiplexing(contd)

• Examples of asynchronous TDM frames
• a. Case 1 Only three lines sending data

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Types of Multiplexing(contd)

• b. Case 2 Only four lines sending data

1 2 3 4 5
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Types of Multiplexing(contd)

• c. Case 3 All five lines sending data

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Types of Multiplexing(contd)

• Inverse Multiplexing
• takes the data stream from one high-speed line
  and breaks it into portion that can be sent
  across several lower speed lines simultaneously,
  with no loss in the collective data rate

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Types of Multiplexing(contd)

• Multiplexing and inverse multiplexing

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Types of Multiplexing(contd)

• Why do we need inverse multiplexing?
• wants to send data, voice, and video each of
  which requires a different data rate.
• example
• voice - 64 Kbps link
• data - 128 Kbps link
• video - 1,544 Mbps link

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8.3 Multiplexing application Telephone system

• Telephone Network

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Multiplexing application(contd)

• Common Carrier Services

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Multiplexing application(contd)

• Analog Service

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Multiplexing application(contd)

• Analog Switched Service
• is the familiar dial-up service most often
  encountered when using a home telephone
• (PSTN Public Switched Telephone Network)

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Multiplexing application(contd)

• Analog Leased Service
• offers customers the opportunity to lease
  line(dedicated line), that is permanently
  connected to another customer.

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Multiplexing application(contd)

• Analog Hierarchy
• To maximize the efficiency of their
  infrastructure, telephone companies have
  traditionally multiplexed signals from lower
  bandwidth lines onto higher bandwidth lines.

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Multiplexing application(contd)

• Analog hierarchy

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Multiplexing application(contd)

• Digital Services
• advantage
• - less sensitive than analog service to noise
• - lower cost

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Multiplexing application(contd)

• Categories of digital service

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Multiplexing application(contd)

• Switched/56 service
• is the digital version of an analog switched
  line
• allows data rates of up to 56Kbps

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Multiplexing application(contd)

• DDS(Digital Data Service)
• is the digital version of an analog leased
  line (maximum speed 56Kbps)

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Multiplexing application(contd)

• DS(Digital Signal) Service
• is a hierarchy of digital signal

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Multiplexing application(contd)

• DS Service
• DS-0 single digital channel of 64Kbps
• DS-1 1,544Mbps,
• 24?? 64Kbps 8Kbps? overhead
• DS-2 6,312Mbps,
• 96?? 64Kbps168Kbps? overhead
• DS-3 44,376Mbps,
• 672?? 64Kbps1,368Mbps? overhead
• DS-4 274,176Mbps,
• 4032??64Kbps16,128Mbps? overhead

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Multiplexing application(contd)

• T Lines

Service
Line
Rate(Mbps)
Voice Channels
DS-A DS-2 DS-3 DS-4
T-1 T-2 T-3 T-4
1,544 6,312 44,736 274,176
24 96 672 4032
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Multiplexing application(contd)

• T line for Analog Transmission

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Multiplexing application(contd)

• T-1 frame structure

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Multiplexing application(contd)

• Fractional T Lines

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Multiplexing application(contd)

• E Lines
• Europeans use a version of T lines called E lines

Voice Channels
Rate(Mbps)
Service
E-1 E-2 E-3 E-4
2,048 8,448 34,368 139,264
30 120 480 1920
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Multiplexing application(contd)

• Other Multiplexing Service
• ISDN(Integrated Service Digital Network)
• SONET(Synchronous Optical Network)
• ATM(Asynchronous Transfer Mode)