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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
Classification of Data Networks
by 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
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Classification of Data Networks
by Switching Technology
• Circuit Switching
– Connection-oriented networks, ideal for realtime 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
11
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)
12
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
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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
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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