1. Telecommunications and Mobile Commerce
Wireline and Wireless Technologies

2. Learning Objectives Understand the basic telecommunications system
Recognize the differences between analog and digital signals
Describe the processes used by modems to send and receive information
Describe the major types of transmission technologies
Describe the major types of networks
Discuss today’s wireless devices and wireless transmission media
Describe wireless networks according to their effective distance
Define mobile computing and mobile commerce
Discuss the major m-commerce applications

3. The Telecommunications System
A 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

4. Analog vs. Digital Signals
Analog 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

5. Analog and Digital Signals

6. 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

7. Modem Types
The U.S. public telephone system was originally designed as an analog network to carry voice signals or sounds
In 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

8. Communications Media and Channels
For 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 wire
Coaxial cable
Fiber-optic cable
Each type of wireline media has relative advantages and disadvantages

9. Twisted-Pair Wire

10. Coaxial Cable

11. Fiber-Optic Cable

12. Advantages and Disadvantages of Wireline Communications Channels
Twisted-pair wire
Inexpensive
Widely available
Easy to work with
Slow (low bandwidth)
Subject to interference
Easily tapped (low security)
Coaxial cable
Higher bandwidth than twisted-pair
Less susceptible to electromagnetic interference
Relatively expensive and inflexible
Easily tapped (low-to-medium security)
Somewhat difficult to work with
Fiber-optic cable
Very high bandwidth
Relatively inexpensive
Difficult to tap (good security)
Difficult to work with (difficult to splice)

13. Transmission Speed
Bandwidth 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 Gbps
Fiber-optic cable: more than 40 Tbps in a laboratory (trillion bits per second)

14. Types of Networks
A 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 reasons
Enable organizations to be more flexible to adapt to changing business conditions
Enable companies to share hardware, software, and data across the organization and among different organizations
Make it possible for geographically dispersed employees and work groups to share documents and ideas
And they are a critical link between businesses and customers

15. Types of Networks
There are various types of computer networks, ranging from small to worldwide
Types 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

16. Wireless Devices
Individuals are finding it convenient and productive to use wireless devices for several reasons:
Can make productive use of time that was formerly wasted
Their work locations are becoming much more flexible
Enables them to allocate their working time around personal and professional obligations
The 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

17. Wireless Transmission Media
Wireless media, or broadcast media, transmit signals without wires over the air or in space
The major types of wireless media are:
Microwave
Satellite
Radio
Infrared
Each of these media has relative advantages and disadvantages

18. Advantages and Disadvantages of Wireless Media
Channel
Advantages
Disadvantages
Microwave
High bandwidth
Relatively inexpensive
Must have unobstructed line of sight
Susceptible to environmental interference
Satellite
Large coverage area
Expensive
Signals experience propagation delay
Must use encryption for security
Radio
Signals pass through walls
Inexpensive and easy to install
Creates electrical interference problems
Susceptible to snooping unless encrypted
Infrared
Low to medium bandwidth
Used only for shot distances

19. Satellite
Satellite transmission systems make use of communication satellites
Three types of satellites around the earth include:
Geostationary (GEO) – TV signals
Medium earth orbit (MEO) – GPS
Low 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?

20. 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

21. Internet over Satellite
In 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

22. Mobile Commerce
Mobile 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 devices
No need for a PC
The “cell phone culture”
Declining prices
Bandwidth improvement

23. M-Commerce Applications
Financial services
Banking and payment
Intrabusiness applications
Content, services, and voice communication portals
Location-based applications
Shopping, location-based services and advertising
Telemedicine
What are some other potential m-commerce applications?
How is m-commerce different from traditional PC-based e- commerce channels?