Telecommunications and Networks Chapter 6

Principles and Learning Objectives Effective communication is essential to organizational success. –Define the terms communication and telecommunications and describe the components of a telecommunications system.

Principles and Learning Objectives An unmistakable trend of communications technology is that more people are able to send and receive all forms of information over greater distances at a faster rate. –Identify three basic types of communications media and discuss the basic characteristics of each. –Identify several types of telecommunications hardware devices and discuss the role that each plays. –Identify the benefits associated with a telecommunications network. –Name three distributed processing alternatives and discuss their basic features. –Define the term network topology and identify five alternatives.

Principles and Learning Objectives The effective use of telecommunications and networks can turn a company into an agile, powerful, and creative organization, giving it a long-term competitive advantage. –Identify and briefly discuss several telecommunications applications.

Overview of Telecommunications Systems

Communications

Telecommunications

Telecommunications Media

Basic Communications Channel Characteristics Simplex channel Half-duplex Full-duplex channel

Bandwidth The range of frequencies that an electronic signal occupies on a given transmission medium.

Broadband Telecommunications in which a wide band of frequencies is available to transmit information, allowing more information to be transmitted in a given amount of time.

Shannon’s Fundamental Law of Information Theory The information carrying capacity of a channel is directly proportional to its bandwidth - the broader the bandwidth, the more information that can be carried.

Types of Media Twisted-Pair Coaxial Cable Fiber-Optic Cable Microwave Transmission/satellite

Twisted-Pair Wire Cable

Coaxial Cable

Fiber Optic Cable

Microwave Transmission

Satellite Transmission

Cellular Transmission

Infrared transmission –Requires line of sight –Used in lan –To connect to a printer

Telecommunications Devices

Devices Modems: –Analog –Digital Special-purpose modems Multiplexers Front-end processors

Modems

Multiplexers

Front-End Processors

Carriers and Services

Common carriers: long distance telco, Value-added carriers: these cos own pvt networks offer services for a fee Switched and dedicated/leased lines: Private branch exchange (PBX) Wide-area telecommunications service (WATS): for 800/888 number, its cheaper than other billing method Phone and dialing services Digital subscriber line (DSL): 500 kbps plus speed, can use telephone and computer at same time,need a special modem ISDN: simultaneously transmit video, data, voice etc in digital form T1 Carrier: 1.5 mbps speed

Integrated Services Digital Network (ISDN)

Carriers and Services

Networks & Distributed Processing

Basic Processing Strategies Centralized processing Decentralized processing Distributed processing

Network Concepts and Considerations Network topology –Ring network –Bus network –Hierarchical –Star network –Hybrid network Network types –Local Area Networks –Wide Area Networks –International networks –Home and small business networks

Network Topology

Local Area Networks

Wide Area Networks

Home and Small Business Networks

Terminal-to-Host Application and database reside on the host

File Server Application and database reside on the file server. Dbms runs on the end users workstation. The data is manipulated on the users station. File server often sends the entire file not just the requested data. So it creates lot of traffic on the network.

Client/Server The server gets the request from the client. Sends a message to the database server which extracts the data, formats and sends it to the client. Here it doesn’t send the entire file but just the data needed. So far less traffic on the network.

Communications Software and Protocols

Communications Software Network operating systems (NOS) Network management software

Communications Protocols Open Systems Interconnection (OSI) model Transmission Control Protocol/Internet Protocol (TCP/IP) Systems Network Architecture (SNA) Ethernet Asynchronous Transfer Mode (TM) Bluetooth

Open Systems Interconnection (OSI) Model

Network Interconnectivity Technology

Bridge, Routers, and Gateways

Telecommunications and Applications

Voice mail Electronic software distribution Telecommuting Videoconferencing Electronic data interchange (EDI)

Videoconferencing

Electronic Data Interchange (EDI)

Public Network Services

Summary Communications - any process that permits information to pass from a sender to one or more receivers Telecommunications media - twisted-pair wire cable, coaxial cable, and fiber-optic cable Modems - convert signals from digital to analog for transmission, then back to digital Ethernet - the most widely installed local area network (LAN) technology