Context-Aware Applications - Guide to Cloud Computing for Business and Technology Managers - page 516

one another are the accuracy they provide and the cost of their imple-
mentation. The most popular network-based positioning techniques are
cell-global-identity (CGI) methods, timing advance (TA), uplink time of
arrival (TOA), and angle of arrival (AOA), while the most popular hand-
set-based positioning techniques are observed time difference of arrival
(OTDOA), enhanced observed time difference (E-OTD), and assisted
Global Positioning System (A-GPS). The accuracy provided by some of
these techniques in different coverage areas of the mobile network is pre-
sented in Tables 23.2 and 23.3.

23.4.2 LBS System Challenges

Despite the appealing idea of using user location information to provide
highly personalized and intelligent services, there are certain challenges
that should be addressed in order for LBS to succeed.
We can divide these challenges into three categories:

1. Technological challenge for LBS is the capability to create easy-to-use
and satisfying services. There is much talk concerning what would
be the most suitable user interface and type of service (pull or push)
in terms of user satisfaction. For example, in the case of push-based
services, a user is not required to manually issue queries in order
to get the information he or she seeks. The system automatically
informs him or her based on the current location and a list of prefer-
ences listed in the user's profile. The problem is that in this way, user
intent cannot be perfectly captured and the user may be frequently
disturbed by out-of-context information. So, despite the easiness of
usage (no or minimal interface), user satisfaction is not assured. On
the other hand, in pull-based LBS, in which clients have to poll the
server for updates, the users may experience difficulties in using
these services because cell phones, PDAs, and wearable computers
are less suitable for browsing and query-based information retrieval
due to their limited input device capabilities. All these restrictions
along with the unpredictability in mobile environments (disconnec-
tions, frequent context differentiations, etc.) have to be taken very
carefully into account when designing LBSs.

Some of the implied requirements are the following:

a. A less intensive use of the mobile network and a minimal vol-
ume of transmitted data

b. The possibility of off-line operation

c. Simple and user-friendly interfaces and limited and well-
specified amounts of presented information content

Therefore, it becomes apparent that LBS will not succeed in attract-
ing users without implementing sophisticated techniques based on