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<concept id="GUID-70E1117B-17F0-5CF4-A5D0-35D3BEBB0FEA" xml:lang="en"><title>Position

Area Data Classes</title><shortdesc>This document describes the basic and extended position area data

classes that contain information about the accuracy of the position returned

to an application when it calls <codeph>RPositioner::GetLastKnownPositionArea()</codeph>. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>LBS maintains a cache of previously calculated position fixes. If an application

calls <xref href="GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575.dita#GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575/GUID-BF3BBDC5-8B12-3374-ACEB-4013E9CFEBEF"><apiname>RPositioner::GetLastKnownLocation()</apiname></xref>, LBS returns

the most recently calculated position. If an application calls <xref href="GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575.dita#GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575/GUID-A8484963-B2C4-339D-AF8C-056792444D89"><apiname>RPositioner::GetLastKnownPositionArea()</apiname></xref>,

LBS returns the position fix that is the best match for the current location

of the mobile device. The current location of the mobile device is estimated

from data received from the network. </p>

<p>The Location Acquisition API defines a set of position area data classes

(figure 1). A client application passes an object of one of these classes

as a parameter when it calls <xref href="GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575.dita#GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575/GUID-A8484963-B2C4-339D-AF8C-056792444D89"><apiname>RPositioner::GetLastKnownPositionArea()</apiname></xref>.

The position area data classes are defined in <filepath>LbsAreaInfo.h</filepath>. </p>

<fig id="GUID-898DA2B8-185E-5906-803A-1871320A0F7E">

<title>           Figure 1. Position Area Data Classes.          </title>

<image href="GUID-4930A22F-EF80-5B08-A878-C0DB73929558_d0e266550_href.png" placement="inline"/>

</fig>

<p>A brief description of the classes follows. Follow the links to more detailed

reference documentation. </p>

<ul>

<li id="GUID-6EFEC1C0-FA51-5700-AF45-C25F69C8FF34"><p> <xref href="GUID-4AD8EC91-7272-3ABA-92AB-E299E85FDC6D.dita"><apiname>TPositionAreaInfoBase</apiname></xref> is

the base class of the position area data classes. Applications create an object

of one of the derived classes. </p> </li>

<li id="GUID-0F54B61E-D87A-5014-8808-863323BBD475"><p> <xref href="GUID-5FA78254-70C7-3105-B6CE-E1A294C8F773.dita"><apiname>TPositionAreaInfo</apiname></xref> contains

basic information about the accuracy of a returned position. Its defines an

enumerated type <xref href="GUID-5FA78254-70C7-3105-B6CE-E1A294C8F773.dita#GUID-5FA78254-70C7-3105-B6CE-E1A294C8F773/GUID-3B9DEDE6-8903-3B26-9CE6-19D6B4833309"><apiname>TPositionAreaInfo::_TArea</apiname></xref> that defines

an estimate of how closely the current device position matches the returned

position. The position accuracy estimate can be from country level down to

street level, depending on how much information is available from the network. </p> </li>

<li id="GUID-7ADA8994-7028-5C76-9870-FB0F4AA82F82"><p> <xref href="GUID-BC7DEDAF-80AE-34DC-8FD8-CF77FA511B3D.dita"><apiname>TPositionAreaExtendedInfo</apiname></xref> extends <codeph>TPositionAreaInfo</codeph> to

provide details about how the accuracy estimate of the returned position was

calculated. </p> <p>An accuracy estimate can be obtained from the network

as some combination of the following: </p> <ul>

<li id="GUID-AA4BFDD9-D024-5F1C-873C-55A18AC7EB10"><p>Mobile Country Code </p> </li>

<li id="GUID-7AEE15CD-33B2-5833-BE64-8E2D2C729DF4"><p>Mobile Network Code </p> </li>

<li id="GUID-4666634D-05C4-59C1-AD51-55A28F67DC3B"><p>Location Area Code </p> </li>

<li id="GUID-B3BEE4FC-8955-5FAC-B382-121F49C8D1D7"><p>Cell ID </p> </li>

</ul> <p>LBS uses combinations of the above to derive the accuracy estimate

returned from <xref href="GUID-5FA78254-70C7-3105-B6CE-E1A294C8F773.dita#GUID-5FA78254-70C7-3105-B6CE-E1A294C8F773/GUID-C8B19BA7-72A0-35CD-AF72-AD74E9C0CE5B"><apiname>TPositionAreaInfo::Area()</apiname></xref>. Your application

can find what types of data were used to calculate the accuracy estimate by

passing an object of class <xref href="GUID-BC7DEDAF-80AE-34DC-8FD8-CF77FA511B3D.dita"><apiname>TPositionAreaExtendedInfo</apiname></xref> to <xref href="GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575.dita#GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575/GUID-A00A1673-10F2-357A-A3CA-FFB4E14F2F8D"><apiname>RPositioner::GetLastKnownLocationArea()</apiname></xref> and

then using the methods shown in figure 1 to check for code and ID matches. </p> </li>

</ul>

</conbody><related-links>

<link><linktext/></link>

<link href="GUID-F6B5F777-D12F-5913-AECE-047DF8C72F1F.dita"><linktext>How to Get

Location Information</linktext></link>