Chapter 4

Telecommunications and Networking

The McGraw-Hill Companies, Inc. 2002. All rights reserved. Irwin/McGraw-Hill

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Chapter Objectives

• To understand the basic performance characteristics of telecommunications and networking technologies.

• To have an appreciation for the trends in telecommunications technologies and how they influence technology options and decisions.

• To understand how it is possible to view telecommunications as an enabler of organizational communications.

• To appreciate the potential for distortion in organizational communications, and how information and telecommunication technologies may help to reduce distortion.

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Organizational Communication

• Communication is the sharing of information between two or more entities.

• Organizational Communication is the sharing of information related to an organization activity between two or more individuals or organizational units.– Sharing of information implies, collection, analysis,

and transmission of information.

– Formal and Informal Communication

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Communication Dyads

• A communication network is made of a series of communication dyads.

• A dyad consists of – Sender– Receiver– Message– Channel– Medium

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Distortion in Communication

• Communication Distortion is the transformation of the meaning of a message by intentionally or unintentionally altering its content.– Lost

– Destroyed

– Modified or Altered

• Noise consists of disturbances in the communication process that interferes with the intended effect of the message.

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Types of Distortion

• Distortion– Routing – the message gets routed to the wrong

receiver or not at all.– Delaying the message – Modifying it the content of the message– Summarizing

• Intentional • Unintentional

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Distortion

Type Intentional Unintentional

Routing Sending a message to wrong person; news leaks

Not knowing where to send message; sending to wrong address

Delaying Purposely waiting for a deadline to go by

Not being able to send message due to overload

Modifying Changing the message; destroying data

Forgetting to include some material in message

Summarizing Leaving negative data out

Not having time to integrate all available material

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Analog and Digital Data

• Analog signals are transmitted as sound waves along a channel such as a copper telephone wire

• Digital signals are transmitted as a series of bits or on/off signals

• A modem converts digital signals into analog signals and another modem can be used to convert analog signals back to digital signals.

• See Figure 4.6

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Telecommunications

• Voice communications require:1. A source device2. A switching system3. A data channel4. A destination device

• Data communications is used to refer to telecommunications involving computerized data.

• Data traffic on the Internet doubles every 100 days.

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• Bandwidth is used to describe the capacity of a communications medium

• bps, bits per second

• kHz, kilohertz and MHz, megahertz

– Narrowband (transmission speeds of 64 kbps or less)

– Wideband (transmission speeds between 64 kbps and 1.544 Mbps)

– Broadband (transmission rates of 1.544 Mbps or higher)

Data Channels

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Data Channels

• Wireline– Twisted pair copper

– Coaxial cable (cable television)

– Fiber-optic cable

• Wireless– Infrared light

– Cellular telephone (analog or digital)

– Microwave

– Satellite (geostationary or low-earth)

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Communication Protocol

• A communication protocol is essentially a set of codes or conventions used for facilitating communications between hardware and software.– IP or Internet Protocol directs packets on the Internet.

– TCP or Transmission control protocol puts the packets in their correct sequence.

– HTTP or hyper text transfer protocol is used to transmit web pages over the Internet.

– Mobile IP provides IP routing for mobile devices.

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Telecommunications

• ISDN or Integrated Services Digital Network is a set of standards that provide additional capabilities for copper wire.

• DSL or digital subscriber line technology refers to a a group of methods for transmitting at speeds up to 8 Mbps over copper wire.

• Cable Modems allow transmission of Internet traffic through the cable TV network.

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Telecommunications

• T-carrier systems are digital transmission systems that take analog voice circuits and converts them to digital form for transmission. Companies typically lease T lines.

• Frame relay carries data packets over the system that vary in length and are referred to as frames.

• Fast Ethernet is a protocol that was designed originally local area networks.

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Networks

• A computer network is used to connect multiple uses and computing devices together, using telecommunications technologies.

• Three classes of networks– Local Area Network (LAN)– Metropolitan Area Network (MAN)– Wide Area Network (WAN)

• Two types of networks– Server-based networks– Peer-to-peer networks

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LAN Components

• LANs employ both wireline and wireless communications– Wireline

• Twisted pair cable, Coaxial cable, & Fiber optical cable

– Wireless• Infrared light, & Radio waves

• A bridge connects two networks of the same type• A router connects several networks• A gateway is used to connect different types of

networks.

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LAN Protocols

• Other Network Protocols– Token ring protocol

• Used in wired LANs

– IEEE 802.11 (WI-FI) • Several variations designed for used in medium range, higher

data rate applications. • Range less than 150 yards and 22 Mbps are possible.

– Bluetooth is a radio frequency technology designed to provide wireless connectivity to a broad range of devices.

• Uses less power than most wireless LAN technologies• Named for Danish King

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LAN Topologies

• Topology is the configuration of the LAN (See Figure 4.15)– Star, Ring, Bus

• Performance can be measured by the mode of the connection.– Simplex transmission, messages can be carried in only

one direction.– Half-duplex, messages can be carried in both directions

just not simultaneously.– Full-duplex, messages can be carried in both directions

simultaneously.

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Intranets and Extranets

• An Intranet is a controlled, self contained grouping of information resources that can be accessed using Web browsers.

• An Extranet is similar to an Intranet but is designed to facilitate communications between two or more business partners.