1. Definition of Location Dependent Query Processing
The continuous development of wireless networks and mobile devices has motivated an intense
research in mobile data services. The advances in wireless and mobile computing allow a mobile
user to perform a wide range of applications once limited to non-mobile hard wired computing
environments. As the geographical position of a mobile user is becoming more tractable, users
need to pull data which are related to their location, perhaps seeking
information about unfamiliar places or local lifestyle data. In these requests, a location attribute
has to be identified in order to provide more efficient access to location dependent data, whose
value is determined by the location to which it is related. Local yellow pages, local events, and
weather information are some of the examples of these data. There are several methods to
process these data
Location of an object or a person is its geographical position on the earth with respect to a
reference point. This information can be characterized by using a number of different
representations including latitude/longitude/altitude or street addresses, etc. and by giving
granularity, accuracy and rate of change (velocity). With the technological advances in cellular
communications and sensing appliances, location of people has become more realtime and
tractable. Location representation may include timestamp information as it may be related to a
moving object/person, and may be represented in various ways
Introduction of Location Dependent Query Processing
Location can be estimated by using deferent methodologies, and will become information as
common as date information. Location Dependent Data (LDD) is defined as data whose value is
determined by the location to which it is related. Local yellow pages, local events, hotel and
restaurant information are some of the examples of these data. Location dependence in queries
implies that the information asked is related to a location but the location is not explicitly known
when the query is asked. For example, “What are the names and addresses of the restaurants
within 5 miles?" asks to find the restaurants within 5 miles of the current position of the query
issuer. In order to provide the answer to the query, first we have to know the location of the issuer.
Query can then be bound to this location. When we find out the issuer's location, the query
becomes Location Aware since; this special location attribute is explicitly stated to be the issuer's
location. A query including any location related attribute in its predicates is defined as a Location
Aware Query (LAQ). Location Based Services are services which provide value-added
information by considering the location of the mobile users in order to give them customized
information.
Technologies for LBS :
Two types of technologies relevant to LBSs are considered
Enabling technologies
These are technologies which make LBSs possible. They are positioning techniques used to
determine the location of a mobile device. Several positioning methods with differentprecision can
be used. For example, the cell-id technique, also called Cell of Origin (COO) or Cell Global
Identity (CGI), allows one to identify the cell in which a certain wireless device is located. This
method takes advantage of the location data that a wireless infrastructure stores about the mobile
devices it serves. However, the precision of cell-id is usually not enough for the purposes of
existing LBSs, as cells in urban environments have a typical size between 500 m and 2 km. Thus,
there is a myriad of other methods to obtain the location of a mobile device, such as Cell Global
Identity with Timing Advance (CGI+TA), Uplink Time of Arrival (UL-TOA) or (TOA), Angle of Arrival

2. (AOA), Observed Time Difference (OTD) or Enhanced Observed Time Difference (EOTD), Global
Positioning System (GPS), network- Assisted GPS (AGPS). There are also methods based on
infrared/RFID, Ultra-Wideband etc
Facilitating technologies
These are technologies which are complementary technologies that provide the contextual
environment where LBSs can be implemented in a value-added fashion. Four facilitating
technologies for LBS are identified:
v The Wireless Access Protocol (WAP) - It enables the access to information from the Internet
taking into account limitations of mobile devices such as processing power and display size. WAP
is a facilitating technology as it allows the specification of semantic links between locations and
information.
v The General Packet Radio Service (GPRS) or 2.5-generation mobile technology (2.5G) - It is
the successor to GSM, which uses circuit-based connections, and Supports packet-based
connections instead. This minimizes the connection time and allows charging based on data
volume instead of airtime.
v The Universal Mobile Telecommunication System (UMTS) or third-generation mobile
technology (3G) - It also uses packet-based connections, but it provides more bandwidth than
GPRS. This could allow the delivery of enhanced content to the user, such as videos of facilities
in nearby hotels