22-02-2013, 09:55 AM
SEMINAR - ROVER: SCALABLE LOCATION-AWARE COMPUTING
ROVER SCALABLE.pdf (Size: 216.68 KB / Downloads: 44)
Introduction
Everywhere we are surrounded by information, some are
always visible, other need some device to be read. Today
it is possible to be in a place and know exactly the GPS
position we are.
Now imagine situation like to be at museum Louvre of
Paris, visit city like Rome, or just walking in a city. Even
now there are all over the place wireless device that can
communicate with us, and in the near future this will be
the standard.
So come back to the situation of a tour in a city...
Imagine group of tourist walking in the city, if each person
of the group receives a handheld device, with audio,
video and wireless communication capabilities - a normal
model of PDA that it is possible to bought everywhere.
If the city, and the PDA could communicate information,
the tourist could be guided in the tour, they could ask for
some specific information and receive the data that explain
what it is, or where they must go to see it or maybe
reserve a place in a museum or in a restaurant.
These system could also give personal information based
on some personal data (interest, hobby,...) of the user so
that he could be helped to find things that he is interested
on it.
Rover: Scalable Location-Aware
Computing
Rover implemented the initial structure and architecture
to create a system scalability that it is awareness in time,
user preference and client capabilities.
It is clear that such a software architecture could be used
in a very large user populations with lots of options that
every user could use.
Rover service
The system developed by Rover can offer to it user 2 service,
data services or transactional services.
Data service are upon text, graphics, audio and video
format. Using the interface that the PDA or the wireless
client device has, it is possible to interact with the server.
Then the server send the available media format to the
device, tuned for the kind of device it ask the information.
Transactional services are just coordination between
clients and server.
But in a use like this it is important to well defined the
attribute of location.
All object, all the client have a precise location in the
world, so it is important to define a function to estimate
the position with the appropriate error value. Rover use
as object localization the GPS (Global Positioning System)
and the radio frequency techniques based on signal
strength or signal propagation delays. Rover utilise three
parameters, value indicates the position calculated, error
indicates the possible error do in estimation and time
stamp to indicate when the estimation was made. It is
obvious the need of this, depending of the use, an error
of some cm or some meter or even 10-20 meters can be
important. When driving if the navigator give to you an
indication with 5 or 10 meters of error it is not important
and the driver will do the right thing.
Communication Interfaces
For the communication with wireless technology, Rover
choose two kind of link-layer:
IEEE 802.11 and Bluetooth
With Bluetooth it is possible to communicate with a 2
Mbps bandwidths and it has a better functionality with
the client in terms of energy, IEEE 802.11 is not so economics
for energy than Bluetooth but it can communicate
with a 11 Mbps bandwidths.
Rover thinks also for all the place where this kind of technology
is not available, here the client use the most common
communication way: cellular wireless.
In figure 3 shows how the Rover controller use other systems
in the world to communicate with the client.
Initial implementation
The Rover prototype system was developed and tested
at the University of Maryland, College PArk, using as
client Compaq iPAQ model H3650 Pocket PCs running
Linux for PDAs, as wireless communication they use a
IEEE 802.11 wireless LANS. Then all PDA have been
connected with a Garmin e-Trex GPS device so to obtain
a device location with an accuracy of 3 - 4 meters. In figure
4 it is possible to see a iPAQ PDA with a Rover client
display, which marks on the screen different user and the
location in an area map.
Conclusion
Actually Rover system works very well with the technology
available, both indoor that outdoor. All the system
could be improved to obtain a greater precision when trying
to locate a client, to be more independent from the
communication device (using more wireless system, so
that there is always a connection available). With the improvements
of the client PDA, it is clear that it will be
possible to put more application and the PDA will have
more capabilities in text and graphics display. This technology
could be helpful in lots of situation (think of a
museum) and the more it will be used, the more application
will be created for it.