CS412 Introduction to Computer Networking

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CS412 Introduction to Computer Networking
Telecommunication

• DSL, Cable, and Mobile Telephone System

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Topics

• Digital Subscriber Line
• Cable
• Mobile Telephone System

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Digital Subscriber Lines

• Bandwidth versus distanced over category 3 UTP
  for DSL.

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Digital Subscriber Lines

• Operation of ADSL using discrete multitone
  modulation.

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Figure 9.1 DMT
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Figure 9.2 Bandwidth division
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Digital Subscriber Lines

• A typical ADSL equipment configuration.

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Figure 9.3 ADSL modem
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Figure 9.4 DSLAM
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Wireless Local Loops

• Architecture of an LMDS system.

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Cable Television

• Community Antenna Television
• Internet over Cable
• Spectrum Allocation
• Cable Modems
• ADSL versus Cable

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Community Antenna Television

• An early cable television system.

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Internet over Cable

• Cable television

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Compared to Telephone System

• The fixed telephone system.

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Spectrum Allocation

• Frequency allocation in a typical cable TV system
  used for Internet access

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Cable Modems

• Typical details of the upstream and downstream
  channels in North America.

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Figure 9.8 Cable modem
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Figure 9.9 CMTS
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ADSL versus Cable

• Discussions

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Mobile Telephone System

• First-Generation Mobile Phones
• Analog Voice
• Second-Generation Mobile Phones
• Digital Voice
• Third-Generation Mobile Phones
• Digital Voice and Data

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Advanced Mobile Phone System

• Area is divided into cells with an antenna
  control by a cell office in each cell
• Cell offices communicate with MTSO
• Transmission frequencies cannot be the same in
  adjacent cells
• Cell size is not fixed
• Smaller cells used in higher populated area

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Figure 7-36
Cellular System
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Advanced Mobile Phone System

• (a) Frequencies are not reused in adjacent cells.
• (b) To add more users, smaller cells can be used.

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Figure 17.2 Frequency reuse patterns
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Cellular Transmission

• Traditionally analog
• FM used to minimized noise
• Digital transmission
• CDPD (Cellular Digital Packet Data)
• Low-speed digital service over existing cellular
  network
• Based on OSI Model
• Modem needed

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Cellular System

• Handoff
• When a mobile telephone leaves a cell
• 1. Its base station notices the signal fading out
• 2. The base station asks all the surrounding base
  stations how much power they are getting from it
• 3. Ownership is transferred to the neighbor base
  station that receives strongest power
• 4. The telephone is informed of its new boss
• 5. If a call is in progress, it will be asked to
  switch to a new channel

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Channels

• 832 full-duplex channels
• Each channel consists of 2 simplex channels
• Transmission channels
• (849-824)MHz/30KHz ? 832
• Receiving channels
• (894-869)MHz/30KHz ? 832
• Typically, actual number of voice channel per
  cell ? 45

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Channel Categories

• The 832 channels are divided into four categories
• Control (base to mobile) to manage the system
• Paging (base to mobile) to alert users to calls
  for them
• Access (bidirectional) for call setup and channel
  assignment
• Data (bidirectional) for voice, fax, or data

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Second-Generation Mobile Phones

• D-AMP
• GSM
• CDMA

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D-AMPS Digital Advanced Mobile Phone System

• (a) A D-AMPS channel with three users.
• (b) A D-AMPS channel with six users.

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GSMGlobal System for Mobile Communications

• GSM uses 124 frequency channels, each of which
  uses an eight-slot TDM system

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GSM

• A portion of the GSM framing structure.

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Third-Generation Mobile PhonesDigital Voice and
Data

• Basic services an IMT-2000 network should provide
• High-quality voice transmission
• Messaging
• Replace e-mail, fax, SMS, chat, etc.
• Multimedia
• Music, videos, films, TV, etc.
• Internet access
• Web surfing, w/multimedia
• 2.5G, 4G,