Mobile and ubiquitous computing

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21 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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Mobile and ubiquitous
computing

Chapter

16
Distributed

systems,
concepts

and
design, 4th edition, 2005,
Coulouris

et al

Ylva
-
Li

Lindh

Gabriella Hammarin


Mobile computing:

How to handle connectedness
of mobile devices




Ubiquitous computing:
Ubiquitous computing is
the method of
enhancing computer
use by
making many computers
available throughout
the
physical environment, but making
them
effectively
invisible to the user.






Mark Weiser






the
“father”
of
ubiquitous
computing


Properties


From the
point

of
view

of
distributed

systems,
there

is
no
essential

difference

between

mobile and ubiquitous
computing


Volatility

is not a
definining

property

of m and u
systems,
other

systems
have

that
property

as
well
.
But

mobile and ubiquitous computing is
concerned

about

all kinds of
volatility
:


failures

of
devices

and
communication

links


changes

in the
characteristics

of
communication

such

as
bandwidht


the
creation

and
destruction

of associations


logical

communication

relationships

between

software
components

resident on the
devices




Mobile Computing: issues


Continuous connectivity


Wireless communication
without

infrastructure



Location awareness and resource discovery


Security



Mobile computing:
Continuous

connectivity

Issues: How to stay connected when moving
between networks or when external factors
such as weather or environment interfere with
signal reception, or nodes are removed


Possible solution: Solution exists to some of the
problems but development is still in progress


which way is the most efficient?


Mobile computing: Wireless
communication

without

infrastructure



Issue: different networks use different
infrastructures and standards to structure its
inhabitant devices. As an outsider enters, it
might be hard to find, recognize and interact
with other devices in the network.


Possible solution: Standard protocols for
association

Ubiquitous computing

Ubiquitous computing is the method of
enhancing computer use by making many
computers available throughout the physical
environment, but making them effectively
invisible to the user.

Mark Weiser, the “father” of

ubiquitous computing


Ubiquitous computing: issues


Localized scalability. Communication over
small and big distances.


Invisibility/visibility. To find all relevant devices
in a ”smart space” and only the relevant


Resource constraints. E g size, battery limits,
cost


Ad hoc networks and topology control

Ubiquitous computing:
Invisibility/visibility

Issue 1: to integrate devices in our environment to such
degree that we no longer are aware of them


Issue 2: To find all relevant devices in a ”smart space” and only
the relevant devices


Possible solution 2: The boundary principle: smart systems
need to have system boundaries that correspond accurately
to meaningful spaces as they are normally defined
territorially and administratively.


Also, Discovery services, a directory service in which
services in a smart space are registered and looked up by
their attributes .

Ubiquitous computing: Localized
scalability
-


Communication over small and big
distances


Issue
: A
greater

distance

between

nodes

leads

to
weaker

communication

because

it’s

more

failure

prone



Possible

solution: Ad hoc
networks

which

not
includes

an access
point

or
base

station.
They

are
built

”on the fly” as a
result

of the
mutual

detection

of
two

or
more

mobile
devices

with
wireless interfaces on the same
vicinity
.

Resource constraints: size, battery
limits, cost…


Issues
:
Both

mobile and
devices

in a smart
space

need

to be small (to be mobile and to
be
invisible
)
which

makes
battery

time
decrease
.
Also

the
range
,
cost

and
maintaining

the
connection

is
important
. With and
increased

number

of
nodes
,
there

will

be a
higher

pressure on the
network
,
causing

negative
effects

on
it’s

bandwith
.



Possible

solution: …

Ad hoc
networks

and
topology

control

issues


1.
How to reach nodes which are out of range


ad hoc networks, a combination of several
smaller networks

2.
Which devices should know about each
other? Hierarchy, should all devices be aware
of all other?

Security

Issues
:

-
What

basis of trust
can

there

be
between

components

that are
able

to
associate

spontaneously
? (man in the
middle
)

-
Privacy

is a major
issue

for
users

who
may

distrust systems
because

of
their

sensing

abilities
.

-
Users

might

not
always

be
aware

of
being

sensed
. (Big
brother

problem/surveillance
).

Security: types of attack

http://searchmobilecomputing.techtarget.com/searchMobileC
omputing/downloads/Mobile_Computing_chp18.pdf

The End