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

Stoc

k Pr

ice

Information

Data Information Knowledge

Data

Information

Summarizing the dataAveraging the dataSelecting part of the dataGraphing the dataAdding contextAdding value

Data Information KnowledgeInformation

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 interchangeableBut “data” will be often preferredLet’s focus on “data” vs. “signal”

From now on

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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….

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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

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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

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analog signal Analog signal changes over time and takes an

infinite number of values

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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?