Data communication refers to the transmission of digital data between computers over a medium like telephone lines. Telecommunication includes both digital and analog transmission of data and voice. Data communication is a subset of telecommunication. A communication network consists of a source that sends messages, a medium like phone lines or fiber optic cables that transmits the data, and a receiver that accepts the messages. Data can be transmitted serially, one bit at a time over a single line, or in parallel, with all bits sent simultaneously over multiple lines.

1. IntroducingIntroducing
Data Communication &Data Communication &
TelecommunicationTelecommunication

2. Data Communication versusData Communication versus
TelecommunicationTelecommunication
• Data communication is the transmission of data from
one place to another (usually computer to computer)
over some type of medium such as telephone line. It
refers specifically to the communication network
which limited in the type of data transmitted
• Telecommunication may includes communication
system that are not considered as data
communication systems. E.g. Telephone

3. Data Communication versusData Communication versus
TelecommunicationTelecommunication
Transm
ission
and
receiptof
Transm
ission
and
receiptofAnalog data
e.g. voice, video, radio, tv
Digital data
(Data processed by
computers)
Telecommunication
Data
Communication

8. Standard OrganizationStandard Organization
 IEEE – Institute of Electrical and Electronics Engineers.
Professional organization whose activities include the
development of communications and network standards.
 ANSI – American National Standards Institute. Voluntary
organization composed of corporate, government, and other
members that coordinates standards-related activities, approves
U.S. national standards, and develops positions for the United
States in international standards organizations.

9. Standard OrganizationStandard Organization
 ISO – International Organization for Standardization.
International organization that is responsible for a wide range
of standards, including those relevant to networking. ISO
developed the OSI reference model, a popular networking
reference model.
 EIA– Electronic Industries Association. Group that specifies
electrical transmission standards. The EIA and TIA have
developed numerous well-known communications standards,
including EIA/TIA-232 and EIA/TIA-449.

10. Standard OrganizationStandard Organization
TIA – Telecommunications Industry Association.
Organization that develops standards relating to
telecommunications technologies. Together, the TIA
and the EIA have formalized standards, such as
EIA/TIA-232, for the electrical characteristics of data
transmission.

11. Basic Components of aBasic Components of a
Communication NetworkCommunication Network
A data communication network is composed of three parts:-
SOURCE – It is a device used to send the message (e.g.
personal computer, telephone or any other device that can
be connected to a network)
MEDIUM – It is a physical path that connects the source
and the receiver and is used to transmit the data (e.g. STP,
UTP, coaxial, fiber optic)
RECEIVER – It is a device that accepts the message and
may not be similar to sender

12. Basic Components of a Communication NetworkBasic Components of a Communication Network

13. Modes of Channel / Data Flow:Modes of Channel / Data Flow:
Simplex, Half- andSimplex, Half- and
Full-Duplex CommunicationsFull-Duplex Communications
• Simplex
- Connection that allows communication in one
direction
• Half-duplex
– Connection that allows communication in two
directions, but not simultaneously
• Full-duplex
– Connection that allows communication in two
directions at once

14. Half- and Full-Duplex CommunicationsHalf- and Full-Duplex Communications
• Benefits of using full duplex:
– Time is not wasted retransmitting frames
because there are no collisions
– Full bandwidth is available in both directions
because the send and receive functions are
separate
– Stations do not have to wait to until other
stations complete their transmission because
there is only one transmitter for each twisted
pair

20. Transmission Modes:Transmission Modes:
Serial and ParallelSerial and Parallel
Data may be transmitted between two points
in two different ways. It can be transmitted as
entire characters or as individual bits.
In computers, these bits may be sent all at
once (in parallel), or one after the other
(serial).

21. Transmission Modes:Transmission Modes:
Serial and ParallelSerial and Parallel
In parallel transmission the entire character is
transmitted all at once
Each bit uses a separate wire. Thus, 8 bits
character require 8 wires.
For serial transmission, each bit is sent over a
single wire, one after the after.