Dr. R. B. Patel
1
CSE
-
302
:
Mobile
Computing
Dr
.
R
.
B
.
Patel
Dr. R. B. Patel
2
Breakthrough
Technology
•
Wireless
communication
networks
–
multiple
networks
“covering”
the
globe
–
world
-
wide
deregulation
and
spectrum
auctions
–
standard
communication
systems
and
air
link
interfaces
•
Portable
information
appliances
–
laptops,
notebooks,
sub
-
notebooks,
and
MNCs
–
hand
-
held
computers
–
PDAs
and
smart
phones
•
Internet
:
–
TCP/
I
P&
de
-
facto
application
protocols
–
ubiquitous
web
content
Dr. R. B. Patel
3
New
Forms
of
Computing
Wireless Computing
Nomadic Computing
Mobile Computing
Ubiquitous
Computing
Pervasive Computing
Invisible Computing
Distributed
Computing
(Client/ Server)
Dr. R. B. Patel
4
Mobile
Computing
Mobile
Computing
•
Using
:
–
small
size
portable
computers,
handheld,
MNC,
and
other
small
wearable
devices,
•
To
run
stand
-
alone
or
network
based
applications
via
:
–
wireless
networks
:
IR,
BlueTooth,
W
-
LANs,
Cellular,W
-
Packet
Data
networks,
SAT,
etc
.
•
By
:
–
nomadic
and
mobile
users
(animals,
agents,
trains,
cars,
cell
phones,
…
.
)
Dr. R. B. Patel
5
Mobile
Computing
•
An
important
question
to
ask
is
which
technology
drove
mobile
computing
to
where
it
is
today?
•
Is
it
the
wireless
network
technology
or
the
miniaturization
and
portable
computing
technology?
•
Unfortunately,
there
is
no
easy
answer
.
An
individual
with
a
Palm
Pilot
will
probably
answer
in
favor
of
the
portable
technology,
whereas
a
UPS
package
delivery
worker
will
be
more
thankful
to
the
wireless
technology
.
•
Whatever
the
right
answer
might
be,
more
important
questions
need
to
be
answered
:
where
are
we
now?
•
And
what
are
the
challenges
and
impediments
facing
mobile
computing?
Dr. R. B. Patel
6
Mobile
computing
•
Mobile
computing
represents
a
shift
in
the
distributed
systems
paradigm
.
•
The
potential
of
decoupled
and
disconnected
operation,
location
-
dependent
computation
and
communication,
and
powerful
portable
computing
devices
gives
rise
to
opportunities
for
new
patterns
of
distributed
computation
that
require
a
revised
view
of
distributed
systems
.
•
However,
factors
such
as
weak
network
connectivity,
energy
constraints,
and
mobility
itself
raise
new
concerns
regarding
the
security,
reliability,
and
even
correct
-
ness
of
a
mobile
computing
system
.
Dr. R. B. Patel
7
Mobile
Computing
•
Migration
is
important
for
survival
•
Mobility
originated
from
the
desire
to
move
either
toward
resource
or
away
from
scarcity
•
Mobile
computing
about
both
physical
and
logical
computing
entities
that
move
•
Physical
entities
are
computers
that
change
locations
•
Logical
entities
are
instances
of
running
user
application
or
a
mobile
agent
•
Mobile
agents
can
migrate
any
where
over
the
Internet
.
•
But
applications
can
only
move
to
a
local
cluster
of
computers
Dr. R. B. Patel
8
Buzzwords
•
Mobile,
ubiquitous,
nomadic,
un
-
tethered
(unsecured),
pervasive
and
any
time,
any
where,
any
person
computing
are
used
by
the
researchers
to
refer
to
computing
that
uses
small
portable
devices
and
wireless
communication
network
.
•
Nomadic
computing
refer
to
limited
migration
–
Migration
is
within
a
building
at
a
pedestrian
speed
–
Interleaved
pattern
of
user
relocation
and
indoor
connections
•
In
the
same
vein,
users
carrying
laptop
with
Dialup
modems
are
engaged
in
nomadic
computing
Dr. R. B. Patel
9
Buzzwords
(contd
...
)
•
Mobile
Computing
requires
:
Wireless
network
to
support
outdoor
mobility
and
handoff
from
one
network
to
the
next
at
a
pedestrian
or
vehicular
speed
•
Traveler
in
car
using
laptop
connected
with
a
GSM
phone
-
engaged
in
mobile
computing
•
Ubiquitous
computing
or
pervasive
computing
refers
to
access
to
computer
network
all
the
time
at
any
location
by
any
person
.
•
Ubiquitous
computing
cannot
be
realized
unless
mobile
computing
matures
.
Dr. R. B. Patel
10
Ubiquitous
Computing
=
Nomadic
Computing
+
Mobile
Computing
No
Network
Fixed
Network
Fixed
Wireless
Network
Wireless
Network
(A)
Wireless
Network
(B)
Nomadic Computing
Mobile Computing
Ubiquitous computing
Dr. R. B. Patel
11
Nomadic
computing
•
It is another name for mobile computing, is the use
of portable computing devices (such as laptop and
handheld computers) in conjunction with mobile
communications technologies to enable users to
access the Internet and data on their home or work
computers from anywhere in the world.
•
People using such a system are sometimes referred
to as
technomads
, and their ability to use that
system as nomadicity.
Dr. R. B. Patel
12
Continued …
•
Nomadicity is the tendency of a person, or group of
people, to move with relative frequency.
•
The need to support today's increasingly mobile workers
with nomadic computing, the use of portable computing
devices and, ideally, constant access to the Internet and
data on other computers.
•
The goal of nomadic computing is to enable a consistent
experience for users anywhere in the world, including as
they travel from one place to another.
Dr. R. B. Patel
13
Continued …
•
A nomadic environment is said to be one that is transparent
to the user, regardless of location, the device and platform
they're using, the available bandwidth, and whether or not
they are in motion at any given time.
•
Standards such as the Internet Engineering Task Force’s
(IETF) Mobile IPv6 standards and Dynamic Host
Configuration Protocol (DHCP) can be said to support
nomadic computing.
Dr. R. B. Patel
14
Ubiquitous Computing
•
Ubiquitous computing names the third wave in
computing, just now beginning.
•
First were mainframes, each shared by lots of
people. Now we are in the personal computing era,
person and machine staring uneasily at each other
across the desktop.
•
Next comes ubiquitous computing, or the age of
calm technology
, when technology recedes into
the background of our lives.
•
This is also called "Third Paradigm" computing.
Dr. R. B. Patel
15
Sentient
computing
•
Sentient computing
is a form of ubiquitous
computing which uses sensors to perceive
its environment and react accordingly.
•
A common use of the sensors is to construct
a world model which allows location
-
aware
or context
-
aware applications to be
constructed.
Dr. R. B. Patel
16
Mobile
Environment
High
-
speed wire
-
line network
Fixed
host
Fixed
host
Fixed
host
Fixed
host
Fixed
host
Fixed
host
Satellite
link
Wireless
radio Cells
Wireless
LAN
Base
station
Mobile
host
Wireless
link
Comm.
cell
Dr. R. B. Patel
17
Wireless
Telecommunication
Networks
Dr. R. B. Patel
18
Emerging
Portable
Information
Devices
Subscriber Identification
Module (SIM)
Motorola
marco
Motorola Envoy
The Pocket PC
The Nokia 9000 Communicator
The Sharp Zaurus
The
Vadem
Clio
Fujitsu Stylistic
2300/ 3400
The First Wrist PC: Ruputer
Japan’s PHS
Phone, Year
2001
Wearable
Computers
The Power
Ring
Dr. R. B. Patel
19
Applications
for
mobile
computing
•
There
are
several
applications
for
mobile
computing
including
wireless
remote
access
by
travelers
and
commuters,
point
of
sale,
stock
trading,
medical
emergency
care,
law
enforcement,
package
delivery,
education,
insurance
industry,
disaster
recovery
and
management,
trucking
industry,
intelligence
and
military
.
•
Most
of
these
applications
can
be
classified
into
:
(
1
)
wireless
and
mobile
access
to
the
Internet,
(
2
)
wireless
and
mobile
access
to
private
Intranets,
and
(
3
)
wireless
and
adhocly
mobile
access
between
mobile
computers
.
Dr. R. B. Patel
20
Beneficiaries
of
ubiquitous
computing
Commuters
Travelers
Stock traders
Medical
Law enforcement
Education
Insurance
Emergency
Trucking
Intelligence
Military
Internet
Intranet
Ad
-
hoc network
Servers
Clients
Dr. R. B. Patel
21
Limitations
of
the
Mobile
Environment
–
Limitations
of
the
Wireless
Network
–
H
eterogeneity
of
fragmented
networks
–
F
requent
disconnections
–
L
imited
communication
bandwidth
–
Limitations
Imposed
by
Mobility
–
Limitations
of
the
Mobile
Computer
Dr. R. B. Patel
22
Continued
…
Frequent
Disconnections
–
Handoff
blank
out
(>
1
ms
for
most
cellular
system)
–
Drained
battery
disconnection
–
Battery
recharge
down
time
–
Voluntary
disconnection
(turned
off
to
preserve
battery
power,
also
off
overnight)
–
Theft
and
damage
(hostile
environment)
–
Roam
-
off
disconnections
Dr. R. B. Patel
23
Continued
…
Limited
Communication
Bandwidth
–
Orders
of
magnitude
slower
than
fixed
network
–
Higher
transmission
bit
error
rates
(BER)
–
Uncontrolled
cell
population
–
Difficult
to
ensure
Quality
of
Service
(QoS)
–
Asymmetric
duplex
bandwidth
–
Limited
communication
bandwidth
exacerbates
the
limitation
of
battery
lifetime
.
Dr. R. B. Patel
24
Continued
…
Limitations
of
the
Mobile
Computer
–
Short
battery
lifetime
(max
~
5
hours)
–
Subject
to
theft
and
destruction
=>
unreliable
–
Highly
unavailable
(normally
powered
-
off
to
conserve
battery)
–
Limited
capability
(display,
memory,
input
devices,
and
disk
space)
–
Lack
of
de
-
facto
general
architecture
:
Handheld,
communicators,
laptops,
and
other
devices
Dr. R. B. Patel
25
Continued
…
Limitations
Imposed
by
Mobility
Lack
of
mobility
-
awareness
by
applications
–
inherently
transparent
programming
model
(object
-
,components
-
oriented,
but
not
aspect
-
oriented)
–
lack
of
environment
test
and
set
API
support
Dr. R. B. Patel
26
Continued
…
Lack
of
mobility
-
awareness
by
the
system
–
networ
k
:
existing
transport
protocols
are
inefficient
to
use
across
heterogeneous
mix
of
fixed/wireless
networks
–
session
and
presentatio
n
:
inappropriate
for
the
wireless
environment
and
for
mobility
–
operating
system
s
:
lack
of
environment
related
conditions
and
signals
–
client/serve
r
:
unless
changed,
inappropriate
and
inefficient
Dr. R. B. Patel
27
Continued
…
Mobile
and
Wireless
Networking
Issues
–
Mobile
IP
–
Wireless
Transport
–
Ad
-
Hoc
Networks
–
Location
Management
–
Wireless
Network
Benchmarking
–
Ad
-
Hoc
Network
Simulation
–
Wireless
Link
Simulation
Dr. R. B. Patel
28
Continued
…
Wireless
and
Mobile
Computing
Models
–
Mobility
-
aware
Client/
Server
using
Proxies
–
Disconnected
Operations
–
Application
-
aware
Adaptations
–
Mobile
Agents
and
Objects
–
Thin
Client/
Server
–
Mobile
Caching
and
Replication
–
Broadcast
Disks
–
Service
Advertisement
and
Brokering
–
Smart
Pones
Dr. R. B. Patel
29
Continued
…
Mobile
file
and
Database
Systems
–
Wireless
File
System
Access
–
Disconnected
File
Systems
–
Mobile
Access
to
C/
S
or
Distributed
Databases
–
Ad
-
Hoc
Database
Systems
–
Checkpointing
–
Database
recovery
–
Mobile
Database
Design
Dr. R. B. Patel
30
Continued
…
Mobile
Transaction
and
Workflow
–
ACID
Relaxation
–
Mobile
Transaction
Models
–
Optimistic
Data
Replication
–
Semantic
-
based
Conflict
Resolution
–
Consensus
in
Mobile
Environment
Dr. R. B. Patel
31
Continued
…
Wireless
and
Mobile
Applications
and
Services
–
Application
Design
for
Wireless
networks
–
Application
Design
for
Mobility
–
Wireless
WWW
Access
–
Active
Badges
(Teleporting)
–
Wireless
Classroom
(Wireless
Campus!)
–
Mobile
Groupware
–
Location
-
sensitive
Yellow
Service
–
Pervasive
Computing
and
Smart
spaces
–
•
.
.
.
.
.
Dr. R. B. Patel
32
Continued
…
Performance
and
QoS
–
QoS
Measures
in
Wireless
and
Mobile
Environments
–
QoS
Guarantees
–
Simulators
and
Emulaors
of
Wireless
Links
–
Simulators
of
Mobile
and
Ad
-
hoc
Networks
–
Wireless
Networking
Benchmarking
Dr. R. B. Patel
33
Continued
…
Emerging
Standards
–
The
802
.
11
b
–
The
BlueTooth
Standard
–
The
Wireless
Application
Protocol
(WAP)
–
The
CompactHTML
–
The
Network
Computer
Reference
Specification
–
Telecom
Standards
:
UMTS
–
…
Dr. R. B. Patel
34
Continued
…
Commuters
Travelers
Stock traders
Medical
Law enforcement
Intranet
Education
Insurance
Emergency
Trucking
Intelligence
Military
Internet
Intranet
Ad
-
hoc network
Servers
Clients
Dr. R. B. Patel
35
Challenges
•
Mobility/context
aware
applications
•
Naming
and
locating
•
Routing
data
and
messages
•
Reliability
in
presence
of
disconnection
•
Data
management
•
Transaction
models
•
Security
Dr. R. B. Patel
36
Continued
…
•
Mobile
computing
affects
entire
spectrum
of
issues
in
computing
•
First
of
all
it
is
distributed
+
mobile
computing
•
Distributed
computing
as
we
know
works
on
static
wired
network
•
Node
may
initiate
computation
somewhere
and
migrate
to
another
place
.
•
So
two
major
problems
that
arise
due
to
mobility
–
Searching
for
current
location
of
a
mobile
node
–
To
impose
a
communication
structure
among
nodes
Dr. R. B. Patel
37
Continued
…
•
Physical
location
of
mobile
host
is
not
the
network
address,
so
how
do
we
route
the
message
to
a
mobile
host
.
•
This
question
is
being
addressed
by
two
different
communities
-
Internet
community
and
cellular
community
•
Work
of
Internet
community
involves
Mobile
IP
–
Aims
at
standards
that
can
extend
IP
in
order
to
deal
with
location
of
mobile
host
–
Mobile
IP
work
assumes
connectionless
packet
switching
scenario
Dr. R. B. Patel
38
Continued
…
•
Cellular
community’s
effort
based
on
location
management
of
cellular
phone
users
•
It
deals
with
connection
-
oriented
communication,
since
it
is
motivated
by
issues
in
call
-
setup
in
telephony
•
Main
problem
in
mobility
management
is
to
find
an
appropriate
tradeoff
between
searching
and
informing
•
Searching
is
performed
when
address
of
the
message
recipient
is
not
known
-
at
least
not
known
precisely
Dr. R. B. Patel
39
Continued
…
•
Informing
is
a
responsibility
of
the
mobile
host
when
it
migrates
•
Extreme
situations
can
be
1.
Mobile
host
never
informs
-
works
for
hosts
receiving
few
messages
and
for
hosts
which
do
not
move
during
receiving
2.
Always
informs
–
works
well
for
hosts
receiving
messages
frequently
Dr. R. B. Patel
40
Continued
…
•
Ad
hoc
network
routing
is
the
ultimate
challenge
•
Ad
hoc
networks
arise
in
rapid
development
scenarios
1.
Emergency
disaster
management
2.
Military
operation
in
remote
sites
3.
Business
meeting
venues
without
infrastructure
support
•
Many
routing
algorithms
are
designed
:
such
as
fisheye,
state
routing,
dynamic
source
routing,
ad
hoc
on
demand
routing,
etc
.
•
There
are
interesting
application
of
conventional
graph
theoretic
problems
in
ad
hoc
network
routing
Dr. R. B. Patel
41
Continued
…
(a) Infrastructure
-
based wireless network
(b)
Ad
hoc
network
Dr. R. B. Patel
42
Continued
…
•
Main
cause
of
loss
of
packets
in
wired
network
is
congestion
because
error
rates
are
very
low
•
In
wireless
network
congestion
still
remains
a
problem,
but
the
situation
is
somewhat
reversed
•
Wired
and
wireless
network
require
different
techniques
to
achieve
reliability
and
flow
control
•
TCP
works
is
unsuitable
for
wireless
network
as
it
interprets
errors
packets
loss
Dr. R. B. Patel
43
Continued
…
ITCP
(split/indirect
TCP)
splits
TCP
into
two
parts
–
One
between
sender
and
local
MSS
of
the
recipient
–
The
other
between
local
MSS
and
recipient
–
If
MH
switches
cell
during
lifetime
of
a
ITCP
connection
center
point
of
connection
moves
to
new
MSS
sender
remains
completely
unaware
about
it
Dr. R. B. Patel
44
Continued
…
•
Disconnection/weak
connection
support
is
important
•
CODA
file
system
provides
support
for
this
•
It
is
implemented
as
client
side
cache
management
system
•
The
issue
concerns
making
a
file
system
highly
available
while
maintaining
consistency
•
Caching
in
mobile
environment
is
quite
different
.
MSS
cannot
keep
state
information
(due
to
scale)
for
all
clients
.
So
invalidation
by
notification
Dr. R. B. Patel
45
Continued
…
•
Categories
of
information
dissemination
1.
Wide
area
services
–
such
as
stock
quotes
on
national
scale
2.
Macro
services
-
such
weather
on
a
regional
scale
3.
Micro
services
-
traffic
condition
is
an
immediate
vicinity
•
Can
be
extend
to
even
picocells
–
such
finding
a
parking
slot
Dr. R. B. Patel
46
Continued
…
Proving
services
will
require
addressing
of
following
new
issues
–
Interoperability
and
adaptability
to
network
environments
ranging
from
high
to
low
bandwidths
and
infrared
communication
links
–
Energy
efficient
data
access
–
Support
for
mobility
and
disconnection
–
Support
for
active
services,
triggers
(even
notification),
and
periodic
data
delivery
.
Dr. R. B. Patel
47
Continued
…
•
Two
modes
of
information
dissemination
are
1.
Publish
2.
Provide
on
demand
•
Publish
data
is
filtered
by
client
and
server
provides
directory
information
for
assisting
the
filtering
•
Advantages
of
information
dissemination
by
publishing
are
–
Hot
spots
can
be
broadcast
frequently
-
which
saves
energy
at
client,
avoid
congestion
–
Directory
helps
client
to
tune
in
selectively
Dr. R. B. Patel
48
Continued
…
•
Handoff
management
–
an
MH
moves
from
one
cell
to
another
while
being
connected
•
Desirable
features
are
–
Probability
of
call
dropping
is
minimized
–
Ping
-
pong
handoffs
avoided
–
Interruption
is
minimized
Dr. R. B. Patel
49
Mobile
Computing
Models
•
The
following
models
of
computing
in
the
mobile
environment
are
currently
being
researched
and
investigated
:
–
Client/Server
–
Client/Proxy/server
–
Disconnected
Operation
–
Mobile
Agents
–
The
Thin
Client
Model
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