Wireline and Wireless Technologies Telecommunications and Mobile Commerce.

Wireline and Wireless Technologies

Telecommunications andMobile Commerce

Learning ObjectivesUnderstand the basic telecommunications systemRecognize the differences between analog and digital

signalsDescribe the processes used by modems to send and

receive informationDescribe the major types of transmission technologiesDescribe the major types of networksDiscuss today’s wireless devices and wireless

transmission mediaDescribe wireless networks according to their effective

distanceDefine mobile computing and mobile commerceDiscuss the major m-commerce applications

The Telecommunications SystemA telecommunication system consists of

hardware and software that transmit information from one location to another

These systems can transmit text, data, graphics, voice, documents, or full-motion video information

They transmit this information with two basic types of signals, analog and digital

Analog vs. Digital SignalsAnalog signals are continuous waves that

transmit information by altering the characteristics of the waves

The characteristics include the wave’s amplitude and frequency

The human voice is an example of an analog signal

Digital signals are discrete pulses that are either on or off, representing a series of bits (0s and 1s)

This quality allows them to convey information in a binary form that can be clearly interpreted by computers

Analog and Digital Signals

Communications Processors

Communications processors are hardware devices that support data transmission and reception across a telecommunications system

One of these devices is a modem whose function is to convert digital signals to analog signals (modulation) and convert analog signals to digital signals (demodulation)

Examples are dial-up, DSL, and cable modems

Modem TypesThe U.S. public telephone system was originally designed

as an analog network to carry voice signals or soundsIn order for this type of circuit to carry digital information,

that information must be converted into an analog wave pattern by a relatively slow dial-up modem

Cable modems operate over coaxial cable (for example, cable TV) and they offer higher speeds than dial-up

A disadvantage is that they use a shared line which may slow transmission speed when large numbers of users access the same modem

DSL modems operate on the same lines as voice telephones and dial-up modems, but DSL signals do not interfere with voice service and they always maintain a connection

Communications Media and ChannelsFor data to be communicated from one

location to another, some form of pathway or medium must be used

These pathways are called communications channels

Examples of wireline media include:Twisted-pair wireCoaxial cableFiber-optic cable

Each type of wireline media has relative advantages and disadvantages

Twisted-Pair Wire

Coaxial Cable

Fiber-Optic Cable

Advantages and Disadvantages of Wireline Communications Channels

Channel Advantages Disadvantages

Twisted-pair wire InexpensiveWidely availableEasy to work with

Slow (low bandwidth)Subject to interferenceEasily tapped (low security)

Coaxial cable Higher bandwidth than twisted-pairLess susceptible to electromagnetic interference

Relatively expensive and inflexibleEasily tapped (low-to-medium security)Somewhat difficult to work with

Fiber-optic cable Very high bandwidthRelatively inexpensiveDifficult to tap (good security)

Difficult to work with (difficult to splice)

Transmission SpeedBandwidth is a measure of channel capacity (and

potential speed of transmission)Why is this an important issue?Analog signal speed is measured in hertz (Hz)Digital signal speed is measured in bits per second

(bps)The speed of particular communication channels

are as follows:Twisted-pair wire: up to 1 Gbps (billion bits per

second)Coaxial cable: up to 1 GbpsFiber-optic cable: more than 40 Tbps in a laboratory

(trillion bits per second)

Types of NetworksA computer network is a system that connects

computers via communications media so that data can be transmitted among them

Computer networks are essential to modern organizations for many reasonsEnable organizations to be more flexible to adapt to

changing business conditionsEnable companies to share hardware, software, and data

across the organization and among different organizationsMake it possible for geographically dispersed employees

and work groups to share documents and ideasAnd they are a critical link between businesses and

customers

Types of NetworksThere are various types of computer

networks, ranging from small to worldwideTypes of networks include:

Local area networks (LANs) – connect two or more devices in a limited geographic region, usually within the same building

Wide area networks (WANs) – networks that cover large geographic areas and are often provided by common carriers such as telephone companies and the international networks of global communications service providers

The Internet

Wireless DevicesIndividuals are finding it convenient and productive

to use wireless devices for several reasons:Can make productive use of time that was formerly

wastedTheir work locations are becoming much more flexibleEnables them to allocate their working time around

personal and professional obligationsThe Wireless Application Protocol (WAP) is the

standard that enables wireless devices to access Web-based information and services

Microbrowsers can work with smaller screen sizes and lower bandwidth

Wireless Transmission MediaWireless media, or broadcast media,

transmit signals without wires over the air or in space

The major types of wireless media are:MicrowaveSatelliteRadioInfrared

Each of these media has relative advantages and disadvantages

Advantages and Disadvantages of Wireless Media

Channel Advantages Disadvantages

Microwave High bandwidthRelatively inexpensive

Must have unobstructed line of sightSusceptible to environmental interference

Satellite High bandwidthLarge coverage area

ExpensiveMust have unobstructed line of sightSignals experience propagation delayMust use encryption for security

Radio High bandwidthSignals pass through wallsInexpensive and easy to install

Creates electrical interference problemsSusceptible to snooping unless encrypted

Infrared Low to medium bandwidthUsed only for shot distances

Must have unobstructed line of sight

SatelliteSatellite transmission systems make use of

communication satellitesThree types of satellites around the earth include:

Geostationary (GEO) – TV signalsMedium earth orbit (MEO) – GPSLow earth orbit (LEO) – Telephone

The characteristics of these systems are described in Table 7.3

A major limitation of GEO satellites is that their transmissions take a quarter of a second to send and return

Under what circumstances would this propagation delay matter?

Global Positioning System (GPS)

The GPS is a wireless system that uses satellites to enable users to determine their position anywhere on earth

GPS is supported by 24 MEO shared satellites

Internet over SatelliteIn many regions of the world, Internet over

Satellite (IoS), is the only option available for Internet connections

Installing cables is either too expensive or physically impossible

IoS enables users to access the Internet via GEO satellites from a dish mounted on the side of their homes

Drawbacks are that there is propagation delay and signals can be disrupted by environmental influences such as thunderstorms

Mobile CommerceMobile commerce (m-commerce) refers to

e-commerce transactions that are conducted in a wireless environment

The development of m-commerce is driven by the following factors:Widespread availability of wireless devicesNo need for a PCThe “cell phone culture”Declining pricesBandwidth improvement

M-Commerce ApplicationsFinancial services

Banking and paymentIntrabusiness applications

Content, services, and voice communication portals

Location-based applicationsShopping, location-based services and

advertisingTelemedicineWhat are some other potential m-

commerce applications?How is m-commerce different from

traditional PC-based e-commerce channels?