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Positioning</title>
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<h1>Network elements of Support for US Emergency Call (E911)
Positioning</h1>

<p>The whole US emergency call positioning system architecture
can be divided into two parts: the US emergency call positioning part and
the GSM BSS part. The US emergency call positioning system consists of the
control and positioning unit PDE (Positioning Determination Equipment) that
communicates over the Lbis interface with the GSM BSS. The PDE determines
the location estimate with the assistance of the Location Measurement Units
(LMU) under its control.</p>


<p>The Data-Sharing Interface (RDSP link) allows the emergency
call positioning system to fetch certain RN configuration data from the SMLC.
It also allows them to receive notification from the SMLC when data is modified.
The Nokia stand-alone SMLC will support RDSP in SW release 2.2. </p>


<p>In the GSM BSS part, the stand-alone Serving Mobile Location
Center controls the overall locationing procedure and the BSC finds and provides
support information from the radio interface for the emergency call position
part through the stand-alone SMLC. In the BSS, the SMLC manages the location
calculation. The SMLC also contains functionality required to support Location
Services. It manages the overall coordination and scheduling of the resources
required to perform the positioning of a mobile. It also generates the final
location response. In one PLMN there may be more than one SMLC. The stand-alone
SMLC uses the Lb/Lb+ interface to the BSC on the BSS centric architecture.</p>


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<p>In the NSS, the Gateway Mobile Location Center (iGMLC)
contains the functionality required to support Location Services. It provides
the external LCS applications with an interface to the PLMN and authorisation
of the applications. It forwards positioning requests from LCS applications
to the PLMN and sends the location result to the application. In one PLMN
there may be more than one GMLC. The Nokia iGMLC is implemented as a separate
network element.</p>


<p>The MSC is responsible for MS subscription authorisation
and the managing of call-related and non-call related positioning requests
of GSM LCS. The MSC requests the MS location from the BSC. MSC positioning
in the NSS communicates over the A interface with BSS.</p>


<p>In the OSS the Nokia NetAct™ can be used to manage all
the elements of the Nokia LCS solution (Nokia BSS, Nokia stand-alone SMLC,
Nokia MSC, Nokia iGMLC).</p>


<p>Nokia does not implement the U-TDOA method (algorithm)
for positioning in its SMLCs, but supports other vendors' U-TDOA
emergency call positioning through the Lbis interface.</p>
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