Transcript Mobile and ubiquitous computing

Mobile and ubiquitous
computing
Chapter 16 Distributed systems, concepts and
design, 4th edition, 2005, Coulouris et al
Gabriella Hammarin
Ylva-Li
Lindh
• 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
scalabilityCommunication 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