Transcript CS412 Computer Networks - Computer Science | Winona State

CS412 Introduction to
Computer Networking &
Telecommunication
DSL, Cable, and Mobile
Telephone System
Chi-Cheng Lin, Winona State University
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
WCB/McGraw-Hill
Cellular System
 The McGraw-Hill Companies, Inc., 1998
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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GSM
Global 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 Phones:
Digital 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, …
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