Mobile_Computing_621351271

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Transcript Mobile_Computing_621351271

Mobile Computing
What is Mobile Computing
• It is use of a wireless network infrastructure
to provide anytime, anywhere,
communications and access to information.
Wireless communication
• Wireless communication is the transfer of information
over a distance without the use of electrical conductors
or wires. The distances involved may be short (a few
meters as in television remote control) or long
(thousands or millions of kilometers for radio
communications).
• The term "wireless" has become a generic and allencompassing word used to describe communications in
which electromagnetic waves or RF (rather than some
form of wire) carry a signal over part or the entire
communication path.
Electromagnetic spectrum (RF Waves) band width
• The electromagnetic signals are generated by the combination of
electrical and magnetic fields
3KHz
300GHz
Radio Communication
Radio, Microwave, Satellite
VLF
LF
MF
HF
VHF
UHF
400THz
Infrared
SHF
EHF
900THz
Light
Waves
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VLF:-Very Low Frequency rang between 3 KHz to 30 KHz
LF:- Low Frequency rang between 30 KHz to 300 KHz
MF:-Middle Frequency rang between 300 KHz to 3 MHz
HF:-High Frequency rang between 3 MHz to 30 MHz
VHF:-Very High Frequency rang between 30 MHz to 300 MHz
UHF:-Ultra High Frequency rang between 300 MHz to 3 GHz
SHF:-Super High Frequency rang between 3 GHz to 30 GHz
EHF:-Extreme High Frequency rang between 30 GHz to 300 GHz
Waves (electromagnetic signals)
Waves (electromagnetic signals) play a very important role as
far as wireless communication is concerned. For a example
when one is talking to somebody a distance away using a cell
phone, the sound waves with which one speaks are converted
into an electrical signal within the cell phone, then the antenna
of the cell phone converts the electrical signal into
electromagnetic waves which are propagated in space either
uni directionally or omni directional depending on the type of
antenna in use. The antenna on the receiving end captures the
electromagnetic waves and converts them into electrical waves
which are further converted into audible sound waves to the
receiving cell phone.
Signals Propagation
• There are three ways for propagation of
signals from source to destination:
 Ground Propagation (Radio Waves)
 Sky Propagation (High Frequency radio
Waves)
 Line of Sight Propagation (High
Frequency Waves)
Mobile Computing Principles
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Decentralization
Diversification
Connectivity
Simplicity
Decentralization
• Mobile computing goes one step further and
distributes the responsibilities between a
variety of small devices.
• Synchronization of information
• Managing Applications
• Development of Heterogeneous System
Diversification
• It affects the functionality of computer system.
• Each device perform specific tasks and
functionalities.
• Devices offer a highly customized functionality
for a particular application context.
• Aim of devices is to best meeting the requirements
of a specific group of users for a specific purpose.
Connectivity
• Mobile computing devices are seamlessly
integrated in an IT world without
boundaries. Emails can be exchanged
between heterogeneous devices, cellular
phones.
• All devices are agreed on common
standards like WAP, UMTS, Bluetooth.
Simplicity
• Information access and management from
these devices is easy.
• User Friendly
• Convenient
Information Architecture in Mobile
Computing
Store &
Process
Information
Servers
Workstations
Devices
Control &
Manage
Information
Create &
Access
Information
Services: Contents, Communication, Access
Standards: Java, HTML, WAP, XML, Bluetooth, GSM
Mobile Computing Devices
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Information Access devices
Intelligent Appliances
Smart Controls
Entertainment Systems
Information Access devices
• Carry around Information and are able to
intermittently plug into intelligent network.
• Include various applications, calendar, Address
book, and mail functionality
• Ex. Handheld Computers
Sub- Notebooks
Cellular Phones
Smart Phones
Handheld Computers
•Handheld computers comprise the largest
group of internet connectable pervasive
devices.
•They are small lightweight and fit into
packets.
•A stylus is used to tap on a touch screen to
activate applications or enter data. On the
basis of operating systems applied on
handheld devices there can be three categories
of handheld computers:

Palm OS-Based Devices

Windows CE-Based

EPOC Based-Handheld Computers
Palm i705
Psion Series 5mx
Device
Class
Palm
Pocket PC
EPOC
A Sample
Product
Palm i705
Casio E-200
Psion Series 5mx
Operating
System
Palm OS 4.1
PocketPC 2002
EPOC
Size
8*12*2 cm
13*7.8*1.6 cm
17*9*2 cm
Display Size
7.8 cm
21-25 cm
12-14 cm
RAM
8 MB
64MB
16 MB
Battery Charge
>10 hours
12 hours
>10 hours
Applications
PIM, Email
PIM, Office suit, Media
Player
PIM, Database spreadsheet, WAP
Intelligent Appliances
• Cover a broad scope of familiar appliances, which are
enhanced by embedding more intelligence and
connectivity using pervasive technologies.
• Sensors are available for air temperature, pressure and to
detect various gases.
• Actuator are controlled electrical switches that are used for
switching lights and appliances on and off.
• Ex. Retail Kiosks, point of sale terminals, Infotainment.
Intelligent Appliances
• Ariston Digital has introduced
First digitally enabled Washing
Machine
• Accepts command through
either internet or through cell
phone.
• Interact with external
telecommunication network
through a special device known
as Telelink.
Merloni Margherita 2000
Smart Controls
• Smart controls are represented by tiny intelligent controls
for thermostats, gas pumps. They are connected to
networks and managed from remote.
• Smart Cards evolved from plastic identification and
magnetic stripe cards through adding a secure temper
resistant single chip microcomputer (25 mm2)
• Smart label is a smart card chip, attached to a radio
frequency antenna coil can hold more information then a
bar code. Data can be written on them and read from them.
Smart Phones
• Combination of Cellular phone &
handheld Computers.
• Ex. Nokia 5800
• Touch screen 3.5G smartphone with GPS,
3.2 megapixel camera with autofocus,
video calling, MP3 player, FM radio,
memory card, Bluetooth™ & WiFi .
Nokia
5800
Entertainment Systems
• These devices offer a combination of
applications and provide improved audio
and video quality.
• Ex. Set-top boxes, Digital Camera, MP3
Player, Intelligent Toys, Game Console.
Software (Languages)
• Java is used because of the platform independency of the
compiled code.
• Many features of Java focus explicitly on small devices:
 Simple & readable
 Secure Language
 Object oriented
Various editions of Java are available :
 J2SE(Standard Edition)
 J2EE(Enterprise Edition)
 J2ME (Micro Edition)
J2ME
• Java Platform, Micro Edition (Java ME) provides a robust,
flexible environment for applications running on mobile
and other embedded devices—mobile phones, personal
digital assistants (PDAs), TV set-top boxes, and printers.
• Java ME includes flexible user interfaces, robust security,
built-in network protocols, and support for networked and
offline applications that can be downloaded dynamically.
• Applications based on Java ME are portable across many
devices, yet leverage each device's native capabilities.
Software (Operating System)
• Windows CE
• Palm OS (latest version 4.0) provides enhanced
security features, Enhanced wireless Internet &
email Access
• Symbian OS (Latest version 7) Real time,
multitasking operating system
• Java Card (smart card operating system) allowa
the applications on a smart card to be written in
Java.
Security
Various Cryptographic patterns and methods are used:
•
Symmetric Cryptographic Algorithms

Data Encryption Standard (DES)

Advanced Encryption Standards (AES)

RC2, RC4, RC5
• Asymmetric Cryptographic Algorithms

RSA Algorithm

Digital Signature Algorithm (DSA)

MD2, MD4, MD5
Connecting The World
Internet protocols and format
• HTTP
• HTML
• XML
Mobile Internet
Two Standards were are established to bring
the benefits of the internet to the mobile
world.
• WAP ( Wireless Application Protocol)
• i-mode (It is introduced by NTT, Docomo in
Japan. It uses cHTML (Compact HTML)
WAP
• WAP is an open technology based on Internet technologies
Allows competition - lower cost
• WAP is backed by major vendors Nokia, Ericsson,
Motorola, Microsoft, IBM.
• WAP supports several wireless systems GSM, IS-136,
CDMA, PDC etc
• Two versions are available WAP 1.1 & WAP 1.2
What can be done with WAP
• Information services
–Similar to web browsing
• Small downloadable programs
–WAP script language is based on JavaScript™
–XML based markup language ( WML )
–Scripting ( WMLS )
WAP Architecture
Web Server
WAP Gateway
WML
WML Encoder
WMLScript
WSP/WTP
WMLScript
Compiler
HTTP
CGI
Scripts
etc.
WTAI
Protocol Adapters
Etc.
Content
WML Decks
with WML-Script
Client
Internet and WAP architecture
Internet
Wireless Application Protocol
HTML
JavaScript™
Other Services and
Applications
Wireless Application
Environment (WAE)
Wireless Session Layer (WSP)
HTTP
Wireless Transaction Protocol (WTP)
TLS - SSL
Wireless Transport Layer Security (WTLS)
TCP/IP
UDP/IP
Wireless Datagram Protocol (WDP)
Bearers:
SMS
USSD
CSD
R-Data
Packet
UDP
PDC-P
Etc...
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