Week 1

Things you want to know

Week 1

• This is a series of things you want to know as you walk away from the course.

• What elements make up a communication system?• How do we classify communications systems?• Give examples of each switching technology.• Describe telecom standards bodies, give examples of

standards. • What are the two types of standards?

Elements of a Communication System

• Source - the originator of the message, whether it is a person or machine.

• Transmitter - the equipment that modifies the message (either data or voice) into the form required for transmission.

• Communications channel - the means of carrying the signal from the source to the destination.

Elements of a Communication System

• Transmission media - may be physical, like a copper wire or fiber optic cable, or atmospheric, like radio waves.

• Receiver - is the device that captures the message from the communications channel and converts it into a form that the person or machine at the destination can understand.

• Destination - the person or machine to whom the message is directed

Elements of a Communication System

Flow of Messages

• Simplex - the type of communication in which messages flow in only one direction, from source to destination.

• Half-duplex communication - occurs when messages travel in both directions between the source and the destination, but in only one direction at a time.

• Full-duplex communication - messages can travel over the communications channel in both directions simultaneously.

Flow of Messages

Relative Number of Sources and Destinations

• One-to-one communication - a single source sends information to a single destination.

• One-to-many communication - a single source simultaneously sends information to multiple destinations.

• Many-to-many communication - occurs when many sources issue messages to many destinations.

Relative Number of Sources and Destinations

10

Classification of Data Networksby Ownership

• Public Network– Owned by a common carrier

• Private Network– Built for exclusive use by a single organization

• Virtual Private Network– Encrypted tunnels through a shared private or

public network

11

Classification of Data Networks by Switching Technology

• Circuit Switching– Connection-oriented networks, ideal for real-

time applications, guaranteed quality of service• Message Switching– Store-and-forward system

• Packet Switching– Shared facilities, Used for data communications

• Cell Switching– Fast processing of fixed length cells

12

Classification of Data Networks by Computing Model

• Distributed Computing– Client/Server set-up

• Centralized Computing– Thin-client architecture

• Some Useful Telecom Terms– Scalability: Ability to increase the power and/or

number of users without major redesigns – RAID (Redundant Array of Independent Disks)– UPS (Uninterruptible Power Supply)

13

Classification of Data Networks by Type of Information

• Data Communications– Digital transmission of information

• Voice Communications– Telephone communications

• Video Communications– Cable TV or video conferencing

ANSI

• The ANSI (American National Standards Institute) - an organization composed of over a thousand representatives from industry and government who together determine standards for the electronics industry.

• ANSI does not dictate that manufacturers comply with their standards, but requests them to voluntarily comply.

TIA and EIA

• The EIA (Electronics Industry Alliance) - is a trade organization composed of representatives from electronics manufacturing firms across the United States.

• TIA (Telecommunications Industry Association) - focuses on standards for information technology, wireless, satellite, fiber optics, and telephone equipment.

IEEE

• IEEE (Institute of Electrical and Electronic Engineers) - an international society composed of engineering professionals.

• Its goals are to promote development and education in the electrical engineering and computer science fields.

ATIS

• ATIS (The Association for Telecommunications Industry Solutions) - a North American trade association made of thousands of companies that provide communications equipment and services.

• Its membership reviews emerging technology and agrees on standards and operating procedures to ensure that services and equipment supplied by multiple companies can be easily integrated.

ISO

• ISO (International Organization for Standardization) - a collection of standards organizations representing 130 countries with its headquarters located in Geneva, Switzerland.

• Its goal is to establish international technological standards to facilitate global exchange of information and barrier-free trade.

ITU

• The ITU (International Telecommunications Union) - a specialized United Nations agency that regulates international telecommunication usage, including radio and TV frequencies, satellite and telephony specifications, networking infrastructure, and tariffs applied to global communication.

• Provides developing countries with technical expertise and equipment to advance their technological base.

Standards

• De facto Standards• Open Computing

Week 1 Links

• www.privateline.com/TelephoneHistory/History1.htm• www.bellsystemmemorial.com/westernelectric history.html• www.bellsystemmemorial.com/bellsystem history.html• www.tecomhistory.org• www.museumphones.com/index.html#t• www.althosbooks.com