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<concept id="GUID-BA49FDC0-808B-5E05-81AC-98637214F304" xml:lang="en"><title>LBS

Quick Start</title><shortdesc>Location Based Services (LBS) provides location information for

installed applications and for remote services via a network. Location information

can be used for location stamping artefacts such as photographs and memos,

finding nearby services and facilities, navigation, and the ability for remote

parties to discover the user's whereabouts. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>Location-based services (LBS) use coordinates from the World Geodetic System

(WGS 84), which is also used as a reference system by the Global Positioning

System (GPS). </p>

<p>The coordinates are based on values for latitude, longitude, and altitude

(elevation above sea level). </p>

<p>The North Pole is 90 degrees North (+90 degrees) and the South Pole is

90 degrees South (-90 degrees). The Equator is defined as 0 degrees; locations

above it have positive latitudes (0 to +90 degrees); those below (0 to -90

degrees) negative ones.</p>

<p>There are two definitions of North Pole; Magnetic North Pole and True (Geographical)

North Pole. Any application with a compass must check how the API defines

North Pole.</p>

<p>The Magnetic North Pole is the point to which compasses point. The True

North Pole defines latitude as +90 degrees. </p>

<p>Meridians are constant longitudinal (north-south) values. The Prime (Greenwich)

Meridian’s value is 0 degrees. WGS84, which LBS use, defines its zero meridian

some 100 meters east of the Prime one. Locations east of the Prime Meridian

have positive longitudinal values (0 to +180 degrees), those west (0 to -180

degrees) have negative ones. </p>

<p>As seen in the figure below, latitude lines are smaller near the poles.

At the equator, one degree of longitude is roughly 111.3 km, whereas at 60

degrees of latitude one degree of longitude is only 55.8 km, which is more

difficult to see.</p>

<fig id="GUID-D98458F6-8EBD-43B9-9C3C-5204BD837D2D">

<image href="GUID-0C01305E-9E73-4E44-BD13-361C93CC5E79_d0e413519_href.png" placement="inline"/>

</fig>

<section id="GUID-D4201DF5-26DD-5E46-B228-A3CAA467C7C6"><title>Getting started

with LBS</title> <p>This section provides links to the most important documentation.</p> <p><b>For

application developers</b> </p> <p>The <xref href="GUID-D0318BB6-0B9F-5A1C-AB0B-61BA22D28661.dita">Location

Acquisition API</xref> is the interface that programmers use to create location-aware

applications. The API gives developers the ability to get location fixes and

to obtain information about the positioning technologies available to the

mobile device. </p> <p><b>For device creators</b> </p> <p>Conceptual information about LBS can be

found in the following documents: </p> <ul>

<li id="GUID-750236F9-A90D-553C-AFA3-3FA2D34897B7"><p><xref href="GUID-7233BC33-6060-5D6B-A5D2-01135F059337.dita">LBS

Architecture Overview</xref> describes the components of the LBS subsystem. </p> </li>

<li id="GUID-4716C614-21DA-586C-874A-24FFA1CBAB0C"><p><xref href="GUID-D18B4715-3942-52EA-9D2F-E145037FA47A.dita">LBS

Integration and Configuration Guide</xref> provides information about the

tasks required to integrate and configure LBS in a device. </p> </li>

</ul> <p>Information about the components

and APIs of the LBS subsystem can be found in the following documents: </p> <ul>

<li id="GUID-06073555-CED8-5204-BC80-446A951CEF28"><p><xref href="GUID-D0318BB6-0B9F-5A1C-AB0B-61BA22D28661.dita">Location

Acquisition API</xref> describes how to create location-aware applications. </p> </li>

<li id="GUID-374A06B3-D988-5B36-A4A3-C64C974159B1"><p><xref href="GUID-CDE5CC9D-F6DE-5A21-97C3-59A2F3398A15.dita">Privacy

requests</xref> explains how LBS protects user privacy when location requests

are received from the network. </p> </li>

<li id="GUID-5B48C1E2-6714-5899-922D-88A5C97A7E6E"><p><xref href="GUID-90757A79-A001-52BF-81D9-CFA02FDDE1BE.dita">Sending

location to a third party</xref> explains how a user can send their location

to a contact or service. The Transmit Location API allows developers to write

applications that allow users to send their location across the network. </p> </li>

<li id="GUID-174B48F4-6125-5A3E-976E-08C09FA33A69"><p><xref href="GUID-23BBC1D8-B3A0-5148-A4F1-22ECF3043E4E.dita">LBS

Administration</xref> explains how to configure LBS settings by using the

LBS Administration API or by configuring a repository initialisation file.

The Administration API provides a means for licensees to write 'control panel'

type applications to permit users to configure LBS behaviour at runtime. </p> </li>

<li id="GUID-DC86A608-1FC6-548F-898F-789D4A797659"><p><xref href="GUID-8F2BA0D3-1549-5837-A105-3AB484CDB80B.dita">A-GPS

Location Data Source API</xref> describes the API that a device creator uses

to build a GPS/A-GPS Positioning Module. It also describes the Symbian A-GPS

Integration Module reference implementation which interfaces with SiRF GPS

hardware. </p> <p><xref href="GUID-B66A425F-3C65-5BF5-ADA2-E25EB7267681.dita">A-GPS

Reference Module </xref> describes the design of the Symbian reference A-GPS

module implementation, which interfaces with SiRF GPS hardware. </p> </li>

<li id="GUID-8E81D82B-4702-5484-9BDE-6B438B1EA696"><p><xref href="GUID-8985B028-4BCD-5858-B22F-EECC52B7B9EB.dita">Network

Protocol Module API</xref> describes the API that a device creator uses to

build a Network Protocol Module. </p> <p>Symbian provides the <xref href="GUID-816334A7-488B-5F91-8C2E-47076D875013.dita">SUPL

Protocol Module</xref> to enable LBS to use the SUPL (Secure User Plane Location)

architecture. </p> </li>

</ul> </section>

<section id="GUID-7ECDED41-D560-4B9A-B0A8-5C9DE379971A"><title>Architecture</title> <p>See <xref href="GUID-7233BC33-6060-5D6B-A5D2-01135F059337.dita">LBS Architecture Overview</xref> for

more information about the LBS architecture. </p> <p>Figure 1 shows the LBS

system model - a component deployment view of LBS. </p> <fig id="GUID-9CA16CBE-F877-5567-9B95-4343049EC809">

<title>              Figure 1. LBS System Model            </title>

<image href="GUID-C5E7D88B-C73D-56D8-A8F4-2393E5EEDC8E_d0e413643_href.png" placement="inline"/>

</fig> </section>

<section id="GUID-CA5D2674-B469-44D8-9255-1F35CA7B8D41"><title>Technologies</title> <p>The

main technologies enabled on the Symbian platform by the LBS subsystem are

as follows: </p> <ul>

<li id="GUID-62F84865-11D4-50BA-A139-7EEA7232BC8F"><p>Global Positioning System

(GPS) </p> <p>The GPS system provides accurate, worldwide positioning. The

main disadvantage of GPS is the long time required to obtain a position fix

when the GPS hardware is first powered. LBS supports Assisted GPS (A-GPS)

to reduce the time required to get a position fix. </p> </li>

<li id="GUID-64669486-6B59-5AE4-A337-E9E50C3C3F1E"><p>Network based positioning </p> <p>Network

based positioning is typically less accurate than GPS, but often provides

a faster fix of adequate accuracy for some applications. </p> </li>

<li id="GUID-05A9FF0E-A974-5CD7-A854-784CB23AA2A4"><p>Secure User Plane Location

(SUPL) v1.0 </p> <p>SUPL defines an architecture for supporting Location Based

Services using IP bearers to connect handsets and network hosts. The Symbian

LBS subsystem contains a SUPL Protocol Module to support SUPL. </p> </li>

</ul><fig id="GUID-52D81395-87C4-4706-97E5-84336EA53C69">

<image href="GUID-0CCCF088-E636-4C12-AA5E-3E2CB04424AD_d0e413682_href.png" placement="inline"/>

</fig><p>The above figure illustrates how the location information can be

provided to the device. Access to these location methods is provided through

the positioning modules.</p> </section>