1. Telecommunications System
Telecommunications is the communication of information by electronic means, usually over some distance.
Today, a great deal of telecommunications transmission is digital data transmission, using computers to transmit data from one location to another.
Deregulation of the telecommunications industry and technology advances have led to an explosion of telecommunications products and services that can create the foundation for a digital business environment.
Managers continually will be faced with decisions about selecting telecommunications technologies and services to enhance the performance of their firm and how best to incorporate them into their information systems and business processes.
A telecommunications system is a collection of compatible hardware and software arranged to communicate information from one location to another.
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

2. Telecommunications System (Cont.)
Telecommunications systems can transmit text, graphic images, voice, or video information.
Essential components of a telecommunications system are:
Computers to process information
Terminals or any input/output devices that send or receive data
Communications channels – the links by which data or voice are transmitted between sending and receiving devices in a network
Communications processors (modems, multiplexers, controllers, and front-end processors), which provide support functions for data transmission and reception
Communications software, which controls input and output activities and manages other functions of the communications network
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

3. Kenneth C. Laudon & Jane P. Laudon
Types of Signals
Information travels through a telecommunications system in the form of electromagnetic signals.
Signals are represented in two ways:
Analog signal
Is represented by a continuous waveform that passes through a communications medium
Is used to handle voice communications and to reflect variations in pitch (voice unit)
Digital signal
Is a discrete, rather than a continuous, waveform
Transmits data coded into two discrete states: 1-bits and 0-bits, which are represented as on-off electrical pulses
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

4. Types of Signals (Cont.)
Most computers communicate with digital signals.
All digital signals must be translated into analog signals before they can be transmitted in an analog system.
The device that performs this translation is called a modem (MOdulation/DEModulation.)
A modem translates a computer’s digital signals into analog form for transmission over ordinary telephone lines, or it translates analog signals back into digital form for reception by a computer.
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

5. Communications Channels
Communications channels are the means by which data are transmitted from one device in a network to another.
High-speed transmission media are more expensive in general, but they can handle higher volumes, which reduces the cost per bit.
A channel can use different kinds of telecommunications transmission media:
Twisted wire
Coaxial cable
Fiber optics
Wireless transmission
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

6. Communications Channels (Cont.)
Twisted wire
Consists of thin copper wires twisted in pairs and is an older transmission medium
Is low in cost but relatively slow for transmitting data
Can carry limited amount of data
Coaxial cable
Like that used for cable television, consists of thickly insulated copper wire, which can transmit a larger volume of data than twisted wire
Is a fast and interference-free transmission medium, with speeds of up to 200 megabits per second
Is hard to wire in many buildings, and cannot support analog phone conversations
Must be moved when computers and other devices are moved
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

7. Communications Channels (Cont.)
Fiber optics
Fiber-optic cable
Consists of thin and clear glass fiber, each the thickness of a human hair, which are bound into cables
Can transmit data (transformed into pulses of light)
Sends the data by a laser device at a rate from 500 kilobits to several trillion bits per second
Is considerably faster, lighter, and more durable than wire media, but more difficult to work with, more expensive, and harder to install
Is well suited to systems requiring transfers of large volumes of data
Backbone – the high-speed network
Consists of fiber-optic cable
Is the part of a network that handles the major traffic, and the primary path for traffic flowing to or from other networks
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

8. Communications Channels (Cont.)
Wireless transmission – sending signals through air or space without being tied to a physical line
Microwave systems (such as communication satellites)
Transmit high-frequency radio signals (straight-line signals that do not bend with the curvature of the earth) and are used for high-volume, long-distance, point-to-point communication
Cellular telephones (cellphones)
Work by using radio waves to communicate with radio antennas (towers) placed within very close geographic areas called cells
Personal digital assistants (PDA)
Are small handheld computers capable of entirely digital communications transmission
Can display, compose, send, receive messages, and provide access to the Internet
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

9. Communications Networks
A number of different ways exist to organize telecommunications components to form a network and hence provide multiple ways of classifying networks.
Networks can be classified by their geographic scope and the type of services provided.
Another way of describing networks is by the way their components are connected, or topology.
The three most common topologies are:
The star network
The bus network
The ring network
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

10. Communications Networks (Cont.)
The network consists of a central host computer connected to a number of smaller computers or terminals.
This topology is useful for applications where some processing must be centralized and some can be performed locally.
All communication between points in the network must pass through the central computer.
Communication in the network will come to a standstill if the host computer stops functioning.
The Star Network
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

11. Communications Networks (Cont.)
The Bus Network
The bus network links a number of computers by a single circuit.
All of the signals are broadcast in both directions to the entire network, with special software to identify which components receive each message.
If one of the computers in the network fails, none of the other components in the network are affected.
The channel can handle only one message at a time, so performance can degrade if there is a high volume of network traffic.
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

12. Communications Networks (Cont.)
The Ring Network
The network does not rely on a central host computer and will not necessarily break down if one of the component computers operates incorrectly.
Each computer in the network can communicate directly with any other computer, and each processes its own applications independently.
Data are passed along the ring from one computer to another and always flow in one direction.
Like the bus network, it is used in local area networks (LANs).
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

13. Communications Networks (Cont.)
Local Area Networks (LANs)
A LAN encompasses a limited distance, usually one building or several buildings in close proximity.
LANs often are used to connect PCs in an office to shared printers and other resources or to link computers and computer-controlled machines in factories.
The server acts as a librarian, storing programs and data files for network users.
The network gateway connects the LAN to public networks or to other corporate networks so that the LAN can exchange information with networks external to it.
A router is used to route packets of data through several connected LANs or to a wide area network.
Wireless Fidelity (Wi-Fi) is the standard for high-speed wireless LANs that can transmit up to 11 Mbps within a 100-meter area, providing a low-cost flexible technology for connecting work groups and providing mobile Internet access.
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

14. Communications Networks (Cont.)
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

15. Communications Networks (Cont.)
Private branch exchanges (PBXs)
Are special-purpose computers designed for handling and switching office telephone calls at a company site
Can store, transfer, hold, and redial telephone calls
Can be used to switch digital information among computers and office devices
Bluetooth
Is another wireless networking standard
Is useful primarily for creating small personal area networks linking up to 8 devices within a 10-meter area using low-power radio-based communication
Wide area networks (WANs)
Span broad geographical distances, ranging from several miles to entire continents
May consist of a combination of switched lines (telephone lines) and dedicated lines (non-switched lines), microwave, and satellite communications.
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

16. Kenneth C. Laudon & Jane P. Laudon
Network Services
Digital subscriber line (DSL) technologies - operating over existing copper telephone lines to carry voice, data, and video
Asymmetric digital subscriber line (ADSL) – supporting a transmission rate of 1.5 to 9 megabits per second when receiving data and up to 640 kilobits per second when sending data
Symmetric digital subscriber line (SDSL) – supporting the same transmission rate for sending and receiving data of up to 3 megabits per second
Cable modems
Are modems designed to operate over cable TV lines
Can provide high-speed access to the Web or corporate intranets of up to 4 megabits per second
Use a shared line so that transmission will slow down if there are a large number of local users sharing the cable line
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon

17. Electronic Business Technologies
Videoconferencing: the ability to confer with a group of people simultaneously using video screens over which participants see each other
Distance learning: education or training delivered over a distance to individuals in one or more locations
Electronic learning (E-learning): instruction using purely digital technology such as CD-ROMs, the Internet, or private networks
Electronic data interchange (EDI): a key technology for electronic commerce
Allows the computer-to-computer exchange between two organizations of standard transaction documents such as invoices, bills of lading, or purchase orders
Transmits an actual structured transaction with distinct fields (the transaction date and amount, and recipient’s name)
Management Information Systems (Eighth Edition)
Kenneth C. Laudon & Jane P. Laudon