Computer Communications
‹ Lecturer
Introduction
– Damian Bourke
‹ E-mail:
[email protected]
‹ Course
Book -
‹ This
course is concerned with the
communications problem:
“How can two remote entities communicate
with each other effectively and efficiently”
» DATA AND COMPUTER
COMMUNICATIONS
– William Stallings
– Prentice Hall International Edition
1
History of Telecommunications
‹
2
Cave Painting - 40,000 to 10,000 BC
Human communication is not limited to verbal interaction
nor to the use of body language. Other non-verbal
interactions include:
– Cave paintings
– The Sumerian System
– The Egyptian System
‹
The speed and range of communication has increased due to:
» The development of the printing press (15th century)
» The development of the railway (19th century)
» The Definition of Time act (1880)
Lascaux, France
3
Sumerian Cuneiform - 3000 BC
4
Hieroglyphic Text
Inscriptions from the Behistun Rock (Western Iran)
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6
1
Model of Communications System
The Telegraph System – The Victorian Internet
‹
Commenced in 1837 (London to Camden)
‹
A key feature is the encoding of text and messages
into dots and dashes
‹
Standardisation was required within each country
Source
Transmitter
» However, incompatibilities existed between countries
Transmission
System
Receiver
Destination
» These were addressed with the introduction of Morse
Code in the 1850’s
‹
To further develop international standards The
International Telegraph Union was set-up in 1865
» Now called the International Telecommunications Union
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8
Complexity in Comupter Networks
Communications Model Components
‹ Source:
Device that generates data
Transforms and encodes data
‹ Transmission System: The physical system
connecting the source and destination
devices
‹ Receiver: Performs reverse function of
Transmitter
‹ Destination: Receives the incoming data
‹ Computer
‹ Transmitter:
9
Course Topics
‹
Introduction
» Communications
Model/Tasks
‹
Signal Analysis
» Signalling concepts
» Bandwidth concepts
» Relationship between Data
Rate and Bandwidth
‹
‹
– Many standards
– Many interconnection technologies
‹ There
is no single underlying theory or
model
– Some models are too complex or too simplistic
‹ There
is a whole raft of TLAs to learn
10
Course Topics
‹
‹
‹
Channel capacity
Transmission Media
‹
Flow Control techniques
» Wired/Wireless
‹
Error detection techniques
‹
Error Control techniques
‹
Sample Link Protocol
‹
Multiplexing
Data Encoding
» Digital/Analogue Data onto
Digital/Analogue signals etc.
‹
‹
Data Transmission concepts
» Digital versus analogue
data/signals/systems
networking is a complex subject:
– Many network technologies
Synchronous / Asynchronous
Transmission Line / Interfacing
configurations
» EIA-232-F/V.24 standards
‹
ISDN interface standards
» Digital/Analogue
Techniques
Transmission Impairments
» Attenuation/Distortion/Noise
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