Transcript Communication and Networks: A historical perspective

Communication and
Networks: A historical
perspective
EPL 324
Andreas Pitsillides
Epl324 Networks: A historical
perspective
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Communicating Humans
From human presence on earth: Some selected examples
• Sign language? ---first (?) intelligent form of communication?
– Allows communicaiton, BUT
– Limited by distance (100’s of meters), coded and limited by lack of
richness of language – Quality of Communication poor.
• Speech
– Richness of language, more natural, but limited by distance (100s of
meters), could be corrupted by noise, i.e many people talking together (a
‘protocol’ or ‘code of conduct’ is required).
• Written
– Richness of language, not necessarily limited by distance, limited by
encrypted form (must know script form). Must have pen and paper (not so
natural). Can be corrupted by e.g. ‘bad’ handwriting or spilling coffee on
the paper (noise)
• Pigeon
– Not limited by distance much, but limited by volume,
– unreliable - message could easily be lost
– (pigeon is not necessarily reliable — could go elsewhere, be eaten by a
vulture, etc.)
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Communicating Humans (cont.)
• Smoke signals
– Limited by distance, limited by
volume (rate of information transfer),
limited by vocabulary-Smoke
ON/Smoke OFF
– [is this a big problem? Recall
digital/binary communication]
– limited by encrypted form (not many
are smoke signal readers—could be
an advantage. When?),
– can be corrupted by wind
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Communicating Humans (cont.)
• Morse code over electrical wires
– Not limited as much by distance,
– limited by volume over a given time
period (information rate),
– limited by encrypted form (not many are
Morse code readers),
– can be corrupted by electromagnetic
noise, but not as easily as the smoke
signal
• Radio signal (as in radio and TV)
– Not limited as much by distance,
– not limited as much by volume,
– not limited by encrypted form, but it is
encoded (modulated),
– can be corrupted by electromagnetic
noise (it touches upon quality of signal).
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Communicating Humans and
communication channels
• Radio signals bounced on upper layers of
atmosphere, or even satellites
– Not limited by distance--universe, not limited
a lot by volume, can be influenced by
weather conditions, can be influenced by
position of satellite (geostationary, etc…)
• Binary (digital) computer signals
– Not limited by distance by using repeaters,
not limited a lot by volume, limited by
encrypted form (not many are data signal
code readers), not as easily corrupted by
noise (if properly designed), offers reliable /
dependable quality
• Light signals (optical fibers)
– Not limited by distance, not limited (at all) by
volume, limited by encrypted form, not
corrupted by e-m noise, offers reliable /
dependable quality
• Power lines
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Some indicative early systems
• Polybius (203-120 BC)
– Coding: B=21, S=34
– 2 sets of 5 torches behind
screens
– 2 torches up = Ready-to-send /
Clear-to-send
– Left screen, then right screen
– Bandwidth: ~ 2 words/minute
– Remained ‘state-of-the-art’ for
roughly 2000 years
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Some indicative early systems
• Claude Chappe (1763-1805)
• 1792: Optical semaphore (arms &
telescopes)
• 2 arms x 7 positions x 4 bar positions =
196 symbols
• Operated by two people
• Can run full-duplex (but hard!)
• Delay: Paris-Lille (190km) in 32 minutes
• Bandwidth: ~ 15 bits/minutes
• Most of the features of modern networks
(routing, error correction, flow control)
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Some indicative early systems
• Electrical Telegraph Morse code
–
–
–
–
–
1837: Cooke and Wheatstone
25 characters/minute
1851: Paris – London cable
1852: 6400km cable in England
1866: London – New York
– 20 words for $100
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Some indicative early systems
• Telephony (“voice over
wires”)
– Reiss (1863), Bell
(1876),Gray(1876),
Edison(1877), Siemens (1878),
....
– “This ‘phone’ has way too many
shortcomings to consider it as a
serious way of communicating.
The unit is worthless to us.”
[Western Union,1876]
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Communicating Humans and
communication channels (cont.)
• What do the earlier examples have in common?
– Human adaptability and ingenuity in finding different (often
‘unnatural’) ways to communicate
– Different channels (guides) have been used (wind, air-space for
pigeons, line-of-sight for smoke signals, radio waves, electricity
signals, e-m waves, microwave guides, light (optical) waves
– Often to surpass limitations of the medium, encryption and noise
cancelling techniques are used. At times information is piggybacked on other more convenient signal (e.g radio modulation)
– Offered quality of service must be at acceptable levels
To achieve our goal of effective and reliable
communication, from anywhere, we need to study
communication and networking (starting with the
fundamentals)
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Networks
• So far we considered communication between 2
points.
• What if we need to communicate with many? Do
we need to establish one-to-one communication
channels with each one? Is this
efficient/practical/feasible?
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Networks
• Previous discussion focused on point-to-point
communication.
• To be more effective and adaptable with our
communication needs and to utilise resources efficiently,
communication networks have been invented (recall other
man made networks).
• Main innovation is
– aspect of sharing a common channel (e.g. in a Local Area
Network) or a number of common resources (e.g. channels /
nodes) and
– relaying (i.e. cooperating) messages for others (e.g. in the first
Telephone system using (manual) switches, in the Internet using
routers, in adhock (e.g. VANETS) and sensor networks with
cooperation between the nodes)
– A world of interconnected IP (internet) devices leading to concepts
such as the Internet of Things, Ambient Intelligence , etc...
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Networks
• Again, as in the choice of appropriate channels, whenever the need
arises, different communication networks have been used, as
the current needs dictate. Examples of different types of networks still
in use:
–
–
–
–
–
–
The Telephone network,
The cellular mobile Telephone Network (GSM, GPRS, UMTS, LTE, 4G)
The Internet
Cable networks
Local Area Networks, Wireless Local Area Networks
Sensor networks, Body Area Networks, Personal Area Networks, Vehicle
Adhoc networks (VANETS), Home Area Networks, …
– etc…
• These networks may use different technologies,
BUT fundamentals remain the same
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Networks
• Different networks and technologies require openness,
interoperability, standards, protocols, etc…
•
Above will be part of the networking course
•
Note: for each one of the above volumes have been written, thousands of
man-years invested by the community in research and development, but the
results today have proven the worth of the investment. Notable examples
include:
– The telephone network which has enabled people to communicate from every part
of the globe
– The Internet (a global network) which allows open access by the world community,
from anywhere in the world
– Worth pointing out that the internet is the most complex-large scale man-made
system
– A view of the evolution of interconnected devices
– And to come, the Internet of Things and ambient intelligence
• Our aim is to cover the fundamentals, touch upon the
technology, brief introduction to analysis of networks, hint upon
traffic engineering and design issues, and open research
questions and challenges. Most of our examples will be drawn
from the internet.
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End
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Point to point connection
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Broadband over power lines ?
IEEE spectrum Dept 2004
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Shared channel Network
Home
WLAN
network
Adhoc
network
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Switching Systems
• Manual control—Switch/cord boards
Off-Hook Indicator
Tip
Ring
Patch Cord
Pairs
Manual Ring
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Network
Common resources
(e.g. routers)
Users
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routers
Cost?
From a few dollars to
millions of dollars
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Internet devices
JPL:
Sensor
Webs
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Internet Map
This graph is using over 5
million edges and has an
estimated 50 million hop
count.
http://www.opte.org/maps/
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Communicating vehicles (Vehicle Adhoc NetworksVANETs)
Wireless links to other cars within hundreds of meters
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Sensor Nodes
UC Berkeley: COTS Dust
UCLA: WINS
UC Berkeley:
UC Berkeley: COTS Dust
Smart Dust
JPL: Sensor Webs
Rockwell: WINS
Many (could be thousands) nodes interconnected via short range radio connections and relaying of messages
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Internet of Things
Smart home
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Intel’s networking
evolution perspective
http://www.bitrebels.com/technology/
the-internet-of-things-every-devicethat-connects-us-infographic/
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