Chapter 6 Telecommunications, Networks, and Wireless Computing

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Oct 30, 2013 (3 years and 8 months ago)

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Chapter 6 Telecommunications, Networks, and Wireless Computing

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Telecommunications, Networks,

and Wireless Computing

SESSION 8

Chapter 6 Telecommunications, Networks, and Wireless Computing

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TELECOMMUNICATIONS


Telecommunications:

Communication
of all types of information, including
digital data, voice, fax, sound, and video
from one location to another over some
type of network



Network:

A group of computers and
associated peripheral devices connected
by a communication channel of sharing
information and other resources among
users

Chapter 6 Telecommunications, Networks, and Wireless Computing

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SENDER

RECEIVER

MEDIUM

Basic Communications Model

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Text


Voice


Image


Video

Types of Data

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Three Major Developments Shaping

Contemporary Systems


1.
Client/server computing


2.
Packet switching


3.
TCP/IP and other communications standards


The Corporate Telecommunications System

Features of Contemporary Telecommunications Systems

Chapter 6 Telecommunications, Networks, and Wireless Computing

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The Corporate Telecommunications System

A corporate telecommunications system

Figure 8
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Client/Server Computing



Powerful personal computers connect to network
with one or more server computers



Has extended networking to parts of business
that could not be served by centralized
architecture



Processing load balanced over many smaller
machines

The Corporate Telecommunications System

Features of Contemporary Telecommunications Systems

Chapter 6 Telecommunications, Networks, and Wireless Computing

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Packet Switching



Messages broken into “packets” before
transmission



Packets include destination and error
-
checking
information



Packets travel independently using routers;
reassembled into original message at destination

The Corporate Telecommunications System

Features of Contemporary Telecommunications Systems

Chapter 6 Telecommunications, Networks, and Wireless Computing

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The Corporate Telecommunications System

Packet
-
switched networks and packet communications

Figure 8
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Packet Switching


Packet switching

breaks transmissions into packets


When a packet arrives at a switch, the switch must decide where to
send the packet next

Switch

Switch

A

B

C

D

E

Trunk Line

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TCP/IP

Transmission Control Protocol/Internet Protocol



Open suite of protocols for connectivity
developed in 1970s


Provides standards for breaking messages into
packets, routing them to destination addresses,
and reassembling them at end


Allows for communication regardless of
hardware/software


The Corporate Telecommunications System

Features of Contemporary Telecommunications Systems

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TCP/IP: Four
-
Layer Reference Model

1.
Application layer:

Communication between applications
and other layers


2.
Transport layer:

Acknowledging and sequencing packets
to/from application


3.
Internet layer:

Addressing, routing, packaging data
packets


4.
Network interface layer:

Placing packets on and
receiving them from network medium


The Corporate Telecommunications System

Features of Contemporary Telecommunications Systems

Chapter 6 Telecommunications, Networks, and Wireless Computing

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The Corporate Telecommunications System

The Transmission Control Protocol/Internet Protocol (TCP/IP) reference model

Figure 8
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Communication
Media/Channels


Guided Media:


Twisted Pair


Coaxial Cable


Optical Fiber



Unguided Media:


Microwave


Satellite


Broadcast Radio

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Twisted Pair

Coaxial Cable

Optical Fiber

Guided Media

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Analogue signal: a
continuous wave



Digital: a discrete set of on
(1) and off (0) electronic
bursts rather than a
continuous wave.

+1

0

0

1

1

0

Analog and digital signals

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Chapter 6 Telecommunications, Networks, and Wireless Computing

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Microwave
-

“Line of sight” media:

antennas need to see each other

Unguided Media: Microwave

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Unguided Media: Satellite

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Transmission Speed


Bps:

Bits per second


Baud rate:

Rate of signal changes


One signal change = cycle


Transmission capacity is function of frequency


Bandwidth:

Range of frequencies
accommodated on a particular channel


The Corporate Telecommunications System

Transmission Media

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The Corporate Telecommunications System

Transmission Speed


Transmission Media

Twisted wire

Up to 100 Mbps

Low cost

Microwave

Up to 200+ Mbps

Satellite

Up to 200+ Mbps

Coaxial cable

Up to 200 Mbps

Fiber
-
optic cable

Up to 6+ Tbps

High cost

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By geographic span


Local Area Network (LAN)


Wide Area Network (WAN)


By topology (physical)


Star


Bus


Ring


Mesh


By architecture (logical)


Peer to peer versus client
-
server


Centralized versus distributed versus hybrid

Computer
Networks

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Network Topology: STAR

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Network Topology: Bus

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Network Topology: Ring

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Communications Networks

Network topologies

Figure 8
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Local Area Networks



Encompass a limited distance



Require its own communication channels



Support high volumes of data and
functions requiring high transmission
speed



Gateway, router, Network Operating
System (NOS)

COMMUNICATIONS NETWORKS

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A Local Area Network (LAN)

COMMUNICATIONS NETWORKS

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Wide Area Networks (WANs)



Span large geographical distance



Consist of variety of switched and
dedicated lines, satellite, and microwave
technologies


COMMUNICATIONS NETWORKS

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Use radio waves to connect stations


802.11b:

Current standard; 54 Mbps in 2.4 GHz
range


Infrastructure mode:

Wireless devices
communicate with wired LAN via access points


Ad
-
hoc mode:

Peer
-
to
-
peer mode; wireless
devices communicate with each other directly


Communications Networks

Wireless Networks: Wi
-
Fi and Bluetooth

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Communications Networks

An 802.11 wireless LAN

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Hot spot:

Geographic location in which an
access point provides public Wi
-
Fi network
service



Bluetooth:
Standard for wireless personal area
networks that can transmit up to 722 Kbps
within 10
-
meter area


Communications Networks

Wireless Networks: Wi
-
Fi and Bluetooth

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Is the World Falling for Wi
-
Fi?


Textbook Page 280

Case Analysis

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Frame relay


Asynchronous transfer mode (ATM)


Integrated Services Digital Network (ISDN)


Digital subscriber line (DSL)


T1 line


Network convergence


VAN: Value Added Network

Communications Networks

Broadband Network Services and Technologies

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E
-
mail



Eliminates telephone tag and costly long
-
distance
telephone charges



Groupware



Enables work groups at different locations to
participate in discussion forums and work on
shared documents and projects


Electronic Business and Electronic Commerce Technologies

Electronic Mail and Groupware

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Voice mail


Digitizes spoken message and transmits it over a
network



Fax


Digitizes and transmits documents over telephone
lines


Electronic Business and Electronic Commerce Technologies

Voice Mail and Fax

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Teleconferencing


Ability to confer with a group of people
simultaneously



Data conferencing


Two or more users can edit and modify data files
simultaneously



Videoconferencing


Participants are able to see each other over video
screens


Electronic Business and Electronic Commerce Technologies

Teleconferencing, Dataconferencing, and Videoconferencing

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Digital Information Services
:


Online services providing general and business
information, such as LexisNexis, AOL, Dow
Jones News


Distance learning


Education or training delivered over a distance to
individuals in one or more locations


E
-
learning


Instruction delivered online using the Internet or
private networks


Electronic Business and Electronic Commerce Technologies

Digital Information Services, Distance Learning, and E
-
Learning

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Computer
-
to
-
computer exchange between two
organizations of standard transaction documents,
such as invoices, purchase orders



Minimizes paper
-
handling and data input;
lowers transaction costs



Transmits structured data with fields, unlike e
-
mail

Electronic Business and Electronic Commerce Technologies

Electronic Data Interchange

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Electronic Business and Electronic Commerce Technologies

Electronic data interchange (EDI)

Figure 8
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1.
Distance

2.
Services

3.
Points of access

4.
Utilization

5.
Cost

6.
Security

7.
Connectivity

Developing a Business
-
Driven Telecommunications Plan

Implementation Issues: Seven Factors