Introduction - Ubiquitous Positioning - page 12

infrastructure is in place there is virtually no limit to the number of simultaneous
users. The downside is that there is considerable complexity at the user end. The
trend in distributed computing, however, is to push intelligence to the edge of
networks so it is likely that the autonomous approach will dominate. Drane [3]
makes the point that a hybrid approach is probably optimal.
1.4.5 The Inadequacies of GPS
Given the dominance of GPS it is a good place to start when considering
Whereness. GPS was such an important milestone that it is now hard to imagine a
world without it, but there are, however, some concerns and limitations. Perhaps
the biggest concern is not about the technology per se, but about ownership and
control of the service. Apart from the user groups for whom it is operated, there
are no service-level agreements in place for anyone else. For an increasingly
global economy with more people dependent on GPS in more countries, it is not
surprising that the political control of GPS raises doubts about its value. One way
around the problem has been proposals and deployments of GPS-like systems
from other power blocks.
GPS is dependent on a network of fixed ground stations for monitoring and
control. While it would be unhelpful for one of the 24 individual satellites to fail,
it would be much more of a problem if an overall system failure occurred. Civilian
aircraft may not use GPS as their only navigation device because of this
vulnerability. Another good reason to have parallel deployment of systems such as
GLONASS and Galileo is to provide system diversity (using multistandard
receivers).
Although GPS works well in many environments outdoors, it has only limited
coverage indoors. It would be useful if there could be methods to provide
positioning of similar performance (i.e., better than 10m accuracy, where sight of
the sky is not possible). Although conventional radio systems such as cellular
radio and broadcasting services can all be used for positioning indoors, there is
little prospect of achieving GPS-like accuracy or better. Given the small scales of
indoor “geography” it would be useful to have better than GPS accuracy. So is
there any prospect of solving the indoor positioning problem? Since the early
1990s ubiquitous computing researchers have been using techniques that, if
adopted universally, would give an adequate performance indoors, and some are
now beginning to become available in devices that are part of the ICT market.
1.4.6 Ubiquitous Computing
Whereness is dependent upon the future of ICT and the digital networked
economy. We must therefore consider where the Internet, telecommunications,
computing (both hardware and software), wireless, sensor and sensing systems,
maps, and GIS are all headed. Although the desktop PC, mobile phone, and the
portable music player are truly ubiquitous, there are (only) about 1 billion PCs