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<h2>GSM-WCDMA handover process</h2>

<p>Nokia GSM-WCDMA Inter-System Handover includes handovers
for coverage and load reasons. The measurement parameters of the WCDMA RAN
neighbour cells are sent to the dual mode GSM/WCDMA mobiles in the Measurement
Information messages.</p>


<p>The BSC performs the evaluation of a handover from GSM
to WCDMA RAN after the evaluation of a downlink level handover.</p>


<p>The following prerequisites must be fulfilled in order
to enable an inter-system handover from GSM to WCDMA RAN:</p>


<ul>
<li><p>The target cell candidates (WBTSs)
are defined as neighbour WCDMA RAN cells for the serving GSM cell in the BSC.</p>
</li>
<li><p>The mobiles (which are in the dedicated
state) are allowed to measure the neighbour WCDMA RAN cells of the serving
GSM cell.</p>


<p>Define the measuring threshold by the parameter <span class="parameter-sem">Threshold
For Multi-RAT MS</span>.</p>
</li>
<li><p>The mobile has sent the neighbour WCDMA
RAN cell measurements to the BSC.</p>
</li>
<li><p>Early classmark sending is allowed
for mobiles in the serving GSM cell.</p>


<p>You can control the early classmark sending by the parameter <span class="parameter-sem">Early Sending Indication</span>.</p>


<p>For more information, see <em>Base Transceiver
Station Handling in BSC</em> and <em>BSS Radio Network Parameter
Dictionary</em> in BSC/TCSM documentation.</p>
</li>
<li><p>The mobile has sent the UTRAN CLASSMARK
CHANGE message to the BSC.</p>


<p>A dual mode GSM/WCDMA mobile sends a UTRAN CLASSMARK CHANGE
message to the BSC if the early classmark sending is allowed in the serving
GSM cell. The content of the message is required by an RNC which controls
the target WCDMA RAN cell of the inter-system handover attempt.</p>
</li>
<li><p>The connection-specific penalty timer
for inter-system handover attempts has been expired.</p>
</li>
</ul>


<p>The BSC initiates an inter-system handover attempt to the
WCDMA RAN if:</p>


<ul>
<li><p>A neighbour WCDMA RAN cell is available
(coverage).</p>


<p>The cell-specific penalty timer does not exist in the BSC
for the WCDMA RAN cell.</p>


<p>Ec/No measured by the mobile has to exceed the handover
threshold <span class="parameter-sem">Minimum CPICH Ec/Io Level</span>.</p>
</li>
<li><p>Traffic load of the serving GSM cell
exceeds the threshold (load).</p>


<p>The load threshold is defined by the following parameter:</p>


<ul>
<li><p><span class="parameter-sem">Min Traffic Load
For Speech Call</span></p>
</li>
</ul>


<p>The use of load threshold is also influenced by the service
priority which is sent by the MSC.</p>


<p>The procedure of the traffic load checking is similar compared
to the BSC-initiated Traffic Reason Handover. The BSC initiates only as many
inter-system handovers as the number of ongoing calls in the serving GSM cell
is over the traffic load threshold. This means that the serving GSM cell is
not emptied into the WCDMA RAN.</p>
</li>
</ul>


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<img alt="urn:mars:dn02247572:2:en:global:cgm_fixed:data:data" border="0" src="NED?action=retrieve&amp;identifier=dn02247572&amp;edition=2&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /><p class="figure-caption">Figure: GSM-WCDMA inter-system handover process</p>
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<h3>Inter-system
handover for speech connection</h3>

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<h6>Example</h6>



<p>The parameter <span class="parameter-sem">Min Traffic Load For
Speech Call</span> has the value 60 (60 %) and the parameter <span class="parameter-sem">Minimum
CPICH Ec/Io Level</span> has the value 18 (-15 dB). </p>



<p>In addition to above, the BSC has received and averaged
measurement results for the neighbour WCDMA RAN cell and calculated the traffic
load of the serving GSM cell:</p>


<ol class="type-odd">
<li type="1"><p>The traffic load of the serving GSM
cell is 45 % and the averaged Ec/No of the WCDMA RAN cell has the value 18
(the averaged Ec/Io level is smaller than -15.5 dB).</p>


<p>In this case the inter-system handover attempt is not possible
due to too low traffic load and low signal quality.</p>
</li>
<li type="1"><p>The traffic load of the serving GSM
cell is 45 % and the averaged Ec/No of the WCDMA RAN cell has the value 19
(the averaged Ec/Io is equal or greater than -15 dB).</p>


<p>In this case the inter-system handover attempt is not possible
due to too low traffic load.</p>
</li>
<li type="1"><p>The traffic load of the serving GSM
cell is 65 % and the averaged Ec/No of the WCDMA RAN cell has the value 19
(the averaged Ec/Io is equal or greater than -15 dB).</p>


<p>In this case, the inter-system handover attempt is possible.</p>
</li>
</ol>
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<p><a href="NED?action=retrieve&amp;identifier=dn03530043&amp;edition=3&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=ned_6#ned_6" onclick="sync(this);return true" shape="rect">Inter-System Direct Access</a></p>


<p><a href="NED?action=retrieve&amp;identifier=dn03530043&amp;edition=3&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=ned_7#ned_7" onclick="sync(this);return true" shape="rect">Inter-System handover penalties and timers</a></p>


<p><a href="NED?action=retrieve&amp;identifier=dn03530043&amp;edition=3&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=ned_8#ned_8" onclick="sync(this);return true" shape="rect">IMSI Based GSM-WCDMA Handover</a></p>
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