pervasive computing unit i part a -...
TRANSCRIPT
M.SARAVANA KARTHIKEYAN
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PERVASIVE COMPUTING
Unit I
Part A 1. What is pervasive computing?
Pervasive Computing is a technology that pervades the users‟ environment by making use of
multiple independent information devices (both fixed and mobile, homogeneous or heterogeneous)
interconnected seamlessly through wireless or wired computer communication networks which are
aimed to provide a class of computing / sensory / communication services to a class of users, preferably
transparently and can provide personalized services while ensuring a fair degree of privacy / non-
intrusiveness.
Pervasive computing integrates computation into the environment, rather than having computers
which are distinct objects. Pervasive computing is the trend towards increasingly ubiquitous an
information environment in which users have access to ICTs throughout the environment. This trend is
particularly associated with the growth of wireless technologies that allow users to access online
information and services remotely and synchronize data between different computers.
2. State Moore’s law
Moore’s law states that, ―For every 18 months, the number of transistors in an integrated electronic
circuit gets doubled with increased performance and without any increase in size‖.
3. What are the principles of pervasive computing?
Decentralization
Diversification
Connectivity
Simplicity
4. What are the basic aspects or of a Pervasive Computing environment?
Multiple devices like car key, mobile phones, car audio system, and navigation system
are integrated in the system.
A large number of different interfaces are used to build an optimized user interface.
There is a concurrent operation of offline, and temporary online systems.
A large number of specialized computer systems are interconnected via local buses and
the internet.
Short range and wide area wireless communication are integrated.
Security element provide unauthorized access.
5. List the characteristics of a Pervasive Computing?
Privacy & Security
Effectiveness of Approach Across Networks
Economic considerations
Quality considerations
Monitoring mechanisms
Adaptability and Flexibility
Practicability
Sustainability
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6. List the characteristics of a pervasive computing environment
Minimal user distraction
Collaborative interaction
User mobility
Context awareness (user/time/location)
Resource and location discovery
Ambient information, calm technology
Event notification
Adaptive interfaces
Invisibility—everyday object augmentation
Anytime/anywhere
7. Define ubiquitous computing.
Mark D.Weiser defined ubiquitous computing as ,―The most profound technologies are those
that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable
from it‖.
This invisible computing is accomplished by means of "embodied virtuality," the process of drawing
computers into the physical world which in turn made computing, omnipresent and appears everywhere
all the time.
8. List the issues involved in pervasive computing technology?
Feature-specific issues
Form-factor-(size)-specific issues
Power-provisioning issues
Weight-specific issues
Shape-specific issues
Cooling-specific issues
Connectivity-specific issues
User Interface-specific issues
Body-safety-specific issues <not for all devices>
Security-specific issues
Processor-choice-specific issues
Operating System-specific issues
Development and execution-environment-specific issues
Cost-specific issues
9. What are the hardware Device Technology for Pervasive Computing?
Power-provisioning technologies
Display technologies
Memory technologies
Communication technologies
Processor technologies
Interfacing technologies
Sensor Technologies
Authentication Technologies
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10. Define Low-power Device Technologies?
Technology that supports device performance with optimized resources in all aspects is said to
be low power device technology. As many of the devices involved in the pervasive computing
environment may have to be small in size and may have to live on their battery / power units,
consumption of lower power, extension of power provisioning period etc. assume critical significance.
In addition, prevention from excessive heating also requires attention. Power requirements can be
reduced by several means right from material selection and chip-level designing to software designing
and communication system designing. Power provisioning technology including the Battery design
technology plays a very important role in the process.
11. List the major display device technologies in pervasive computing?
Cathode Ray Tube based Displays (CRTs)
Liquid Crystal Displays (LCDs)
Active Matrix Displays
Thin Film Transistor Displays (TFTs)
Passive Matrix displays
Single Scan Displays (Colour Super-Twist Nematic: CSTNs)
Dual Scan Displays (Dual Super-Twist Nematic: DSTN)
High-Performance Addressing displays (HPAs)
Light Emitting Diode based Displays (LEDs)
Organic LED based Displays (OLEDs)
Light-Emitting Polymer based Displays (LEPs)
Chip-on-Glass Displays (CoGs)
Liquid Crystal on Glass Displays (LCoGs)
12. What are all the major hardware components considered while designing a pervasive device?
The pervasive computing devices are needed to be small, less power consuming, highly human
interacted. So the following the components are targeted..
Battery (Nickel Cadmium,Nickel Metal Hydride,Lithium-ion)
Displays (CRT,LCD,LED,OLED,CoG,LCoG)
Memory (SRAM,DRAMUt-RAM,MRAM,FRAM)
Processors (Intel SpeedStep Technology,Crusoe processor)
13. What is the latest technology emerged in batteries?
The latest in battery technology is the emergence of lithium polymer cells, which use a gel
material for the electrolyte. The batteries are made from a few thin and flexible layers, and do
not require a leak-proof casing. This means the batteries can be made in any shape or size.
14. Define Crusoe processor.
The Crusoe processor consists mostly of software. The relatively small processor is designed as a
128-bit very long instruction word processor capable of executing up to four operations per cycle.
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15. List the human machine interfaces associated with mobile and pervasive computing devices.
Navigation keys
Haptic interfaces
Keyboards
Handwriting recognition
Speech recognition
Touch screen technology
16. What do you mean by ―Fitaly‖?
The fitaly keyboard arranges the letters based on their individual frequency and the probability of
transitions in the English language. The name is derived from the orders of letters in one of the top rows
of the layout, just as the QWERTY layout.
17. What is an Octave?.
Another approach to enter a text without real or on-screen keyboard is used by octave from e-
acute. Octave maps each letter of the alphabet to one of eight unique strokes. The strokes are based on a
common characteristics part of the letters they represent and are located around the tips of a star shaped
pattern.
18. What is meant by Bio-Metrics?
Biometrics is the science and technology of measuring and analyzing biological data. In
information technology, biometrics refers to technologies that measure and analyze human body
characteristics, such as DNA, fingerprints, eye retinas and irises, voice patterns, facial patterns
and hand measurements, for authentication purposes.
19. List the operating systems available for mobile computing devices like PDA, other embedded
systems.
Palm OS
EPOC OS
WINDOWS CE OS
QNX NEUTRINO
BeOS
EMBEDDED LINUX
20. What is PALM OS?
Palm OS is the computer operating system that provides a software platform for the Palm
series of handheld personal digital assistants (PDAs) made by Palm Inc. According to Palm,
Palm OS was designed from the beginning to fit into a palm-size device of a specific size and
with a specific display size.
21. Explain briefly about BE OS.
BeOS is a powerful OS designed primarily for Multimedia desktop use. Originally BeOS
was designed for a custom computer system known as the BeBox that had special multimedia
input/output features, and was later ported to the Macintosh, and finally ported to the PC.
22. What are all the device characteristics which require J2me?
Small amount of available memory (128-512kb)
Limited energy (battery operated)
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Connected to a network
Restricted graphical display capabilities
23. List the configuration and technologies available for pervasive devices based on J2me?
Connected device configuration
Connected , Limited device configuration
Embedded Java
Java card
Real time java
24. Define Roaming Environment?
Roaming Environment: An environment that allows connectivity and communication to
the services outside the home zone is called a Roaming Environment. Some sample devices that
may involve Roaming-based access <fixed / mobile roaming>:
PDAs / Palmtops / Pocket PCs / Cell phones / Smart phones / WAP phones
Laptops / Tablet PCs / Notebook PCs
Desktop PCs / Servers / Web TVs
Kiosks
Invisible computing devices / Smart interactive posters
Wearable computers
25. What are the components of pervasive computing?
Components of Infrastructure for Pervasive Computing include Mobile computing
devices, Fixed computing devices, Multimode RF Mobile communication infrastructure <Fixed-
to- Mobile and Mobile-to- Fixed communication system interfaces>, Trust system (security and
privacy), Protocol stacks and Personalized service frameworks.
26. How does mobile internet protocol overcome the address problems of IPv4?
To overcome the address problems of IPv4 for mobile nodes mobile IP uses two IP
addresses: a fixed home address and care of address that changes at each new point of
attachment.
27. What are three steps involved in the process of Synchronization?
Pre synchronization: Prepare for actual synchronization, i.e. authentication,
authorization ,determination of device characteristics
Synchronization: Local IDs are mapped to Global IDs, and data are exchanged.
Post synchronization: Clean up tasks are performed, update the mapping tables.
28. List the characteristics of IrDA.
Frequency band
Security
Transmitting capabilities
Bandwidth
Speech
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29. List the basic security concepts involved in pervasive computing applications.
Identification
Authentication
Authorization
Transaction authorization
Digital signature endorsed by password
Transaction authentication number
Non repudiation
30. List the Challenges of device management in Pervasive Computing?
Tracking the device location
Device user relationship
Version control of devices and software that are out in the field
Software updates of existing devices
Installation of new software on existing devices.
Part B
1. Describe the principles of pervasive computing with examples.
<First list the principles one by one>
Decentralization
Diversification
Connectivity
Simplicity
<Then explain each topic in connection to pervasive computing >
Decentralization
Distributed systems
Having logic, database, control in a distributed style, not in a single machine-
centralized controller.
Synchronizing Information
Use applications on mobile devices and related data to be updated with networked
systems
Managing Applications
For example cellular phone network, tracking and billing are very essential
processes. Scalable managing application server and high end backend systems
are deployed.
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Diversification
Targeting specific needs
Clear move from universal computers (all in one) to diversified devices
challenging performance, price and functionality.
Diversified devices are aim at best meeting the requirements of a specific
group of users for a specific purpose.
Four alternatives to surf the web
Several tools might have some overlap in functionality: preferred tools for each
specific purpose.
1. One can use internet screen phone at home and enjoy multimedia effects.
2. For mobile internet access, a wireless connected handheld computer is the
choice even it has less graphical capabilities and small display.
3. Third one is WAP phone, a ultra-light and very handy and can’t enjoy
multimedia effects.
4. PC with single OS with multiple functionalities and work load can be
used for the same purpose ., but memory requirement is high when
compared to others…such case windows CE version can be employed
which requires a feasible memory capacity.
Managing the Diversity
It’s a challenge to manage device diversity, since each with different capabilities. The
delivery platform as many difficulties in providing common applications.
For example in case of e- shopping website in a WAP phone, user cannot see the
images representing services or objects.
Connectivity
A vision of boundless connectivity
Manifold devices are seamlessly integrated in an IT world without boundaries.
Exchange information through infra-red, data cable, Bluetooth.
Cellular phones with GSM, CDMA also involved in the environment.
Real life obstacles
Platform specific issues: obstacle for application and information exchange.
Devices with different persistent storage ranging from kilobytes(smart card) to
gigabytes(multimedia systems)
Different OS and variety of processors put various restrictions.
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Agreeing on common standards
Achieving connectivity and interoperability between devices is possible only when the
objects are supposed to follow common standards (ISO-OSI, etc…).
When it comes to application data exchange across devices, JAVA is the path finder,
since JAVA is platform independent.
Representation of data in variety of devices of multiple characteristics is resolved by the
introduction of XML.
Concepts like jini or UPnP help devices to discover suitable services in a network to
which they can delegate specific tasks. Automatic reconfiguration based on self-attach
and detach (plug & play capability) implies self-explained and easy usage of network-
connected utilities. With jini, networks turn into a dynamic and distributed system.
Simplicity
Device operations need to be easy, so that the user shall feel comfort with his
needs.
User Interfaces should not have complicated operations.
At present ―one touch ―keys are designed for user easiness.
Touch screen with relevant symbols, images help user to interact well.
Handwriting recognition, speech recognition enabled interfaces, simplifies the
user actions and makes him comfort with the system.
2. With neat diagram explain Biometrics system.
BIOMETRICS is not limited to fingerprint, it involves face recognition, DNA, Palm print,
hand geometry, iris recognition, which has largely replaced retina, and odor/scent.
Related to the behavior of a person. Examples include, but are not limited to typing rhythm,
gait, and voice. Some researchers have coined the term behaviometrics for this class of
biometrics.
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In this system, the user characteristic (fingerprint, voice…) is captured using a specific sensor
and its features are extracted to have a template .This template will be stored in the database
for reference.
In a simple system, when a user provides the characteristic like fingerprint, the system
extracts the features and compares it with the template stored earlier. If it is same the system
allows him.
Generation of reference value at the time of extracting features and template designing and
also at the time of comparison is subject to distortion.so there is always a possibility of
biometric system authentication failure.
FAR: False Acceptance Rate-probability that the system accepts the wrong user.
FRR: False Rejection Rate-probability that the system rejects correct user.
So we can have a combination of both SIM card (user id module) and bio-feature in the
system.
Here the FAR, FRR are very very low.
Key features of Biometrics:
•Universality – each person should have the characteristic.
•Uniqueness – is how well the biometric separates individuals from another.
•Collectability – ease of acquisition for measurement.
•Performance – accuracy, speed, and robustness of technology used.
•Acceptability – degree of approval of a technology.
3. Explain the Palm OS architecture and development cycle
Palm OS
Most successful OS for PDA
Available with palm, handspring, IBM, Sony..
Optimized limited number of features
Low (memory, CPU usage):leads to longer battery life
Version 3.5(256 colors)
Version 4.0(65k colors, Bluetooth support)
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OS features: User management: used as personal device with single user operating
system Task management: one application at a time and one can call other
application Power management: sleep/doze/running mode OS size:V3.5/1.4 MB/runtime memory:64kb User Interface: handwriting recognize/single button access Memory management: dynamic heap/storage
Development cycle
Supports c, c++(c almost/c++ a little)\
C-best choice for performance critical applications
C-simple and fast, Extensive system library
Free SDK based on GNU for windows,Mac,Linux
Commercial IDE –Metro codewarrior (editor, compiler,debugger,visual
graphical user interface constructor)
Palm applications are event-driven and synchronous
Several VM available KVM (Sun),J9 (IBM),WabaVM(Wabasoft)
Palm emulator: emulates a Palm H/W in a PC
Code is compiled –run-debug-edit-compiled
Until a ultimate program is achieved
Finalized code is downloaded to Palm from the emulator
4. Write short notes on
a.J2EE
In today's heterogeneous environment, enterprise applications have to integrate
services from a variety of vendors with a diverse set of application models and other
standards. They require bringing together a variety of skill sets and resources, legacy data
and legacy code.
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The J2EE platform breaks the barriers inherent between current enterprise
systems. The unified J2EE standard wraps and embraces existing resources required by
multitier applications with a unified, component-based application model.
Key features:
Java™ Database Connectivity (JDBC™) API
Transaction Service
Java Naming and Directory Interface™ (JNDI) API
Java™ Message Service (JMS) API
JavaMail™ API
b.J2ME
J2ME stands for Java 2 Platform, Micro Edition. The edition is targeted at small,
standalone or connectable consumer and embedded devices. The J2ME
technology consists of a virtual machine and a set of APIs suitable for tailored
runtime environments for these devices. The J2ME technology has two primary
kinds of components – configurations and profiles.
The configuration and technologies available for pervasive devices based on J2me:
Connected device configuration
Connected , Limited device configuration
Embedded Java
Java card
Real time java
c. Real time Java
Direct memory access: Java RTS allows direct access to physical memory,
making it similar to J2ME. One of the main target platforms of real-time Java is
embedded systems. This means that now you can create device drivers written in
pure Java. Java RTS defines a new class that allows programmers byte-level
access to physical memory, as well as a class that allows the construction of
objects in physical memory.
Asynchronous communications: Java RTS provides two forms of asynchronous
communication: asynchronous event handling, and asynchronous transfer of
control. Asynchronous event handling means the developer can now schedule the
response to events coming from outside the JVM. Asynchronous transfer of
control provides a carefully controlled way for one thread to interrupt another
thread in a safe manner.
High-resolution Timing: There are several ways of specifying high-resolution
time including absolute and relative time. Nanosecond accuracy is available for
time scheduling and measurements.
Memory management: There are two new types of memory areas, immortal
memory and scoped memory. Immortal memory holds objects without destroying
them, except when the program ends. Scoped memory is used only while a
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process works within a particular section, or scope, of the program (such as in a
method). Objects are automatically destroyed when the process leaves the scope.
5. Explain Mobile IP
Mobile IP was developed as a means for transparently dealing with problems of
mobile users which enables hosts to stay connected to the Internet regardless of their
location.
Enables hosts to be tracked without needing to change their IP address
Requires no changes to software of non-mobile hosts/routers
Requires addition of some infrastructure
Have no geographical limitations
Requires no modifications to IP addresses or IP address format
Supports security
Mobile IP Entities
Mobile Node (MN)
The entity that may change its point of attachment from network to network in the
Internet
Detects it has moved and registers with ―best‖ FA
Assigned a permanent IP called its home address to which other hosts send
packets regardless of MN’s location
Since this IP doesn’t change it can be used by long-lived applications as MN’s
location changes
Home Agent (HA)
This is a router with additional functionality
Located on home network of MN
Does mobility binding of MN’s IP with its COA (care of address)
Forwards packets to appropriate network when MN is away
Does this through encapsulation
Foreign Agent (FA)
Another router with enhanced functionality
If MN is away from HA then it uses an FA to send/receive data to/from HA
Advertises itself periodically
Forward’s MN’s registration request
De-capsulate messages for delivery to MN
Care-of-address (COA)
Address which identifies MN’s current location
Sent by FA to HA when MN attaches
Usually the IP address of the FA
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Correspondent Node (CN)
End host to which MN is corresponding (eg. a web server)
Mobile IP Support Services
Agent Discovery
HA’s and FA’s broadcast their presence on each network to which they are
attached
Beacon messages via ICMP Router Discovery Protocol (IRDP)
MN’s listen for advertisement and then initiate registration
Registration
When MN is away, it registers its COA with its HA
Typically through the FA with strongest signal
Registration control messages are sent via UDP to well-known port
Encapsulation – just like standard IP only with COA
Decapsulation – again, just like standard IP
Mobile IP Operation
A MN listens for agent advertisement and then initiates registration
If responding agent is the HA, then mobile IP is not necessary
After receiving the registration request from a MN, the HA acknowledges and
registration is complete
Registration happens as often as MN changes networks
HA intercepts all packets destined for MN
This is simple unless sending application is on or near the same network as the MN
HA masquerades as MN
There is a specific lifetime for service before a MN must re-register
There is also a de-registration process with HA if an MN returns home
Registration Process
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Tables maintained on routers
Mobility Binding Table Visitor List
IP Tunneling
Data packets addressed to the Mobile Node are routed to its home network, where the
Home Agent now intercepts and tunnels them to the care-of address toward the
Mobile Node. Tunneling has two primary functions: encapsulation of the data packet
to reach the tunnel endpoint, and decapsulation when the packet is delivered at that
endpoint. The default tunnel mode is IP Encapsulation within IP Encapsulation.
6. Write a detailed note on device connectivity protocols
Wireless protocols: suitable for small hand held devices (PDA, mobile phones)
WAP (Wireless Application Protocol)
OBEX
IrDA
Bluetooth
IEEE802.11B(11Mbps)
WAP
Leading standard for information services on wireless terminals like digital
mobile phones.
WAP standard is based on Internet standards (HTML, XML and TCP/IP)
WAP consists of a WML language specification, a WMLScript (a light JavaScript
language) specification & Wireless Telephony Application Interface (WTAI)
specification.
WAP is published by the WAP Forum, founded in 1997 by Ericsson, Motorola,
Nokia, and Unwired Planet.
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Object Exchange (OBEX)
Devices can use this to exchange data objects. Designed to enable devices
supporting infrared communication to exchange a wide variety of data and
commands
An object pushes of business cards to someone
Synchronizing calendars on multiple devices using OBEX
Enables applications to work over the Bluetooth technology protocol stack as well
as the IrDA stack
RFCOMM is used as the main transport layer for OBEX.
Devices using the OBEX:
PC
Notebook
PDA
Mobile Phone
Bluetooth
Bluetooth wireless technology is a short-range communications technology
Key features of Bluetooth technology are robustness, low power, and low cost.
Can connect to other Bluetooth enabled devices located in proximity to one another.
Piconets are established dynamically and automatically as Bluetooth enabled devices
enter and leave radio proximity
A Piconet (can constitute 7 devices )
A device belong to several piconets
Features: Range of Bluetooth technology is application specific
Bandwidth upto 1 Mbps and operates in 2.4 GHz (ISM band)
Supports three digital speech channels simultaneously
a minimum range of 10 meters or 30 feet
Version 4.0 Low Energy, adopted December 2009
Version 3.0 High Speed (HS), adopted April 2009
Version 2.1 Enhanced Data Rate (EDR), adopted July, 2007
1 Mbps for Bluetooth low energy technology
1 Mbps for Version 1.2; Up to 3 Mbps supported for Version 2.0 EDR
Up to 24 Mbps supported for Version 3.0 HS