Telecommunications and Mobile Commerce Wireline and Wireless Technologies

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

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

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

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 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

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

Twisted-Pair Wire

Coaxial Cable

Fiber-Optic Cable

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)

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)

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

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

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

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

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

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?

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 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

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

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?