Post on 11-Jan-2016
Info and comm: terminology
tkkwon@snu.ac.kr
Outline
Data vs. Information Data vs. signal Communications Networks Service Protocol Convergence
Data vs. Information
Data raw facts no context just numbers and
text
Information data with context processed data value-added to data
summarized organized analyzed
Data vs. Information
Data: 51007 Information:
5/10/07 May 10th in 2007. $51,007 The average starting salary of an accounting major. 51007 Zip code of Bronson, Iowa.
Data vs. Information
Data 6.34 6.45 6.39 6.62 6.57 6.64 6.71 6.82 7.12 7.06
1 2 3 4 5 6 7 8 9 10 $5.60
$5.80
$6.00
$6.20
$6.40
$6.60
$6.80
$7.00
$7.20
$7.40
Company A
Last 10 Days
Sto
ck P
rice
Information
Data Information Knowledge
Data
Information
Summarizing the data
Averaging the data
Selecting part of the data
Graphing the data
Adding context
Adding value
Data Information Knowledge
Information
Knowledge
How is the info tied to outcomes?
Are there any patterns in the info?
What info is relevant to the problem?
How does this info effect the system?
What is the best way to use the info?
How can we add more value to the info?
“Data” and “information” are interchangeable
But “data” will be often preferred
Let’s focus on “data” vs. “signal”
From now on
9
Analog data vs. digital data
Analog data – data has continuous values, e.g. sound, image,… Depending on storage format: LP, VHS magnetic tape Natural phenomenon
Digital data – data has discrete values e.g. text, integers,… Depending on storage/device: DVD, digital camera Most computing devices
Analog-to-Digital Converter (ADC)
Due to information technologies VLSI, DSP, digital communications, …
Digital data
Bit Nibble Byte (octet) Any binary stream …
Now almost every kind of data is converted to digital….
12
Image as digital data
an artifact, usually two-dimensional, that has a similar appearance to some subject
a pixel (picture element) is the smallest piece of information in an image
A pixel is one bit long in black and white A pixel requires much longer bits in color
systems E.g. red, green, and blue
Other digital data
text Voice? Audio/sound? Video? Binary code
14
Data vs. signal
Digital data vs. analog data Digital signal vs. analog signal Data are symbols like numbers that carry info.
while a signal refers to physical representation of data, electrically or electromagnetically
signal
A signal is a time-varying value (electric or electromagnetic representation) or event that conveys information from a transmitter to a receiver
16
analog signal
Analog signal changes over time and takes an infinite number of values
17
Digital signal
Digital signal changes over time and takes a limited number of values
0 1 11 0 0 0 1 0
Analog signal
A continuous function of time and location An analog signal can be represented by a sum of
periodic signals within a relatively small range Why?
Signal 101
function of time and location parameters of periodic signals:
period T, frequency f=1/T, amplitude A, phase shift E.g., sinewave is expressed as
s(t) = At sin(2 ft t + t)
Any signal can be represented by a sum of periodic signals
: phi [fee]
signal
Different representations of signals Amplitude over time (time domain) frequency spectrum (frequency domain)
phase state diagram (amplitude M and phase in polar coordinates)
f [Hz]
A [V]
I= M cos
Q = M sin
A [V]
t[s]
Analog signal is the winner
Analog signal occupies less frequency spectrum High frequency component suffers from high
attenuation
In data domain, digital is the winner
That’s why there are so many modems
Modem: modulator and demodulator DSL modem, CATV modem, LTE modem, WiFi
modem…
Advantages of Digital (data) Transmission
Digital technology Low cost LSI/VLSI technology
Data integrity Longer distances over lower quality lines
Capacity utilization High bandwidth links economical High degree of multiplexing easier with digital techniques
Security & Privacy Encryption
communications
a process of transferring information from one entity to another via a medium/channel
Transmission and reception Data – signal - data
(computer) networks
a group of interconnected computing devices Medium
Wire vs. wireless
Scale BAN, PAN, LAN, MAN, WAN
Relationship Client-server, peer-to-peer
Topology Tree, bus, star,…
Network operator * Why switches/routers?
* source, sink, origin, destination, sender, transmitter, receiver
protocol
A protocol is a set of rules which is used by computers to communicate with each other across a network
A protocol is a convention or standard that controls or enables the connection and data transfer between computing endpoints
service
the provision of functions within a systems environment
a mechanism to enable access to one or more capabilities, where the access is provided using a prescribed interface and is exercised with constraints and policies as specified by the service description
a network service is an application running at the network application layer and above, that provides functionalities like storage, manipulation, presentation, communication
A service provider is an entity that provides services to other entities. ISP, NO, CP, …
Players in Mobile Networks
Customer Mobile network operator (MNO)
Also called wireless internet service provider (ISP) Mobile virtual network operator (MVNO)
Content provider (CP) In-house vs. third party
Equipment vendor Also called Manufacturer
CATV: System operator (SO), network operator (NO), program provider (PP), MSO (multiple SO)
Internet: ISP, NO, MVNO, CP
convergence
Convergence (telecommunications): the combination of multiple services through lines of telecommunication from a single provider Triple play service Quadruple play service
Technological convergence: a trend where some technologies having distinct functionalities evolve to technologies that overlap E. g. Mobile phones are another good example, in
that they increasingly incorporate digital cameras, mp3 players, camcorders, voice recorders, and other devices.
More heterogeneous case?