Chi-Cheng Lin, Winona State University

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 PhonesAnalog Voice

Second-Generation Mobile PhonesDigital Voice

Third-Generation Mobile PhonesDigital 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

Figure 7-36

WCB/McGraw-Hill The McGraw-Hill Companies, Inc., 1998

Cellular System

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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 analogFM used to minimized noise

Digital transmissionCDPD (Cellular Digital Packet Data)

Low-speed digital service over existing cellular network

Based on OSI ModelModem needed

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Cellular System Handoff

When a mobile telephone leaves a cell1. Its base station notices the signal fading out2. 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 boss5. If a call is in progress, it will be asked to

switch to a new channel

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Channels

832 full-duplex channelsEach channel consists of 2 simplex

channelsTransmission 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 categoriesControl (base to mobile) to manage

the systemPaging (base to mobile) to alert users

to calls for themAccess (bidirectional) for call setup

and channel assignmentData (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 Phones:Digital Voice and Data

Basic services an IMT-2000 network should provideHigh-quality voice transmissionMessaging

Replace e-mail, fax, SMS, chat, etc.

Multimedia Music, videos, films, TV, etc.

Internet accessWeb surfing, w/multimedia

2.5G, 4G, …