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<div class="div">
<h1>Overview of Dynamic Abis</h1>

<p>Dynamic Abis, introduced in BSS10.5 ED, is an application
software. Note, however, that it is a prerequisite of implementing EGPRS support
in the BSC and in the PCU.</p>


<p>As enhanced data rates per radio time slot can vary between 8.8 and
59.2 kbit/s, traditional static <a href="NED?action=retrieve&amp;identifier=general_glossary&amp;edition=13&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=id06953#id06953" onclick="openSmallPopup(event,'NED?action=retrieve&amp;identifier=general_glossary&amp;edition=13&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=id06953#id06953');return false" shape="rect" target="_blank">Abis</a> allocation
does not use transmission resources efficiently. Dynamic Abis makes it possible
to define common transmission resources for EDGE-capable TRXs situated in
the same Abis external PCM circuit (ET-PCM). This common resource is called
the Dynamic Abis pool (DAP) and it is comprised of consecutive Abis ET-PCM
timeslots. There are fixedly allocated transmission resources for Abis signalling
links and traffic channels in the Abis ET-PCM as before, but additional resources
can be reserved for EGPRS calls from the Dynamic Abis pool when necessary.</p>


<p>Abis channel mapping is arranged so that the standard GSM
TRXs are connected to the BSC in a conventional fashion:</p>


<ul>
<li><p>the radio interface TCHs get a fixed 16 kbps channel allocation</p>
</li>
<li><p>the TRXSIG signalling has a fixed channel of 16, 32, or 64 kbps</p>
</li>
<li><p>the OMUSIG has a fixed channel of 16 or 64 kbps.</p>
</li>
</ul>


<p>These bits are reserved permanently for the TRX signalling (TRXSIG)
and O&amp;M messages (BCFSIG). Dedicated TCH channels are allocated for standard
CS services, such as speech.</p>


<p>The same applies to GSM/EDGE TRXs, but when the radio timeslot
demand (retransmission, buffering, and signalling included) exceeds 16 kbit/s,
MCS-2 or higher is used and the BSC allocates Abis capacity for data calls
from the EGPRS Dynamic Abis pool (<a href="NED?action=retrieve&amp;identifier=general_glossary&amp;edition=13&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=id018267#id018267" onclick="openSmallPopup(event,'NED?action=retrieve&amp;identifier=general_glossary&amp;edition=13&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=id018267#id018267');return false" shape="rect" target="_blank">EDAP</a>). Normal
GPRS calls with CS-2 also need additional transmission capacity from the Dynamic
Abis pool when allocated to EGPRS territory, that is, when EDGE-capable TRXs
are configured to use Dynamic Abis.</p>


<p>EGPRS and Dynamic Abis use a new type of PCU frame to connect
with the Abis L1 interface. Each TCH in the radio interface has one corresponding
fixed sub-timeslot in the Abis 2Mb frame just as in the GSM system. For PSD,
this sub-timeslot is called the PCU master data frame. If necessary, the system
can allocate up to 4 extra PCU slave data frames for a given master data frame
to transfer both GPRS and EGPRS data.</p>


<a name="nov2831442501" shape="rect"></a>
<div>
<img alt="urn:mars:dn02263256:2:en:global:cgm_fixed:data:data" border="0" src="NED?action=retrieve&amp;identifier=dn02263256&amp;edition=2&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /><p class="figure-caption">Figure: Abis PCM structure </p>
</div>


<p>The required EDAP resources for MCSs are allocated according
to the table below. In the downlink direction, the required DAP resources
are allocated with 16 kbps resolution for the CS/MCS. In the uplink direction,
the required DAP resources are always allocated for the maximum CS/MCSs that
can be admitted to an MS.</p>


<a name="nov164913191" shape="rect"></a>
<div>
<p>Table: Usage of PCU slave data frames</p>


<table border="1">
<thead>
<tr align="left" char="" charoff="50" valign="bottom">
<th colspan="1" rowspan="1" valign="top"><p></p>


 </th>
<th colspan="1" rowspan="1" valign="top"><p>No slaves</p>
</th>
<th colspan="1" rowspan="1" valign="top"><p>1 slave</p>
</th>
<th colspan="1" rowspan="1" valign="top"><p>2 slaves</p>
</th>
<th colspan="1" rowspan="1" valign="top"><p>3 slaves</p>
</th>
<th colspan="1" rowspan="1" valign="top"><p>4 slaves</p>
</th>
</tr>
</thead>
<tbody>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>CS-1</p>
</td>
<td colspan="1" rowspan="1"><p>X</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>CS-2</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p>X</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>CS-3</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p>X</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>CS-4</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p>X</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>MCS-1</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>MCS-2</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p>X</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>MCS-3</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p>X</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>MCS-4</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p>X</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>MCS-5</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p>X</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>MCS-6</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p>X</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>MCS-7</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p>X</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>MCS-8</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p>X</p>
</td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>MCS-9</p>
</td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p></p>


 </td>
<td colspan="1" rowspan="1"><p>X</p>
</td>
</tr>
</tbody>
</table>
</div>


<a name="nov26418654" shape="rect"></a>
<div class="topic">
<h2>Capacity restrictions</h2>

<p>The maximum size of an EDAP is 12 PCM timeslots: a single TRX can handle
a maximum of 64 x 16 kbps channels, 16 of which are reserved for CS traffic
or for PCU master channels. This leaves 48 x 16 kbps channels (which equals
12 PCM timeslots) for the EDAP.</p>


<ul>
<li><p>PCU restrictions:</p>


<ul>
<li><p>You can create a maximum 16 DAPs in
one PCU.</p>
</li>
<li><p>There can be a maximum of 256 channels
(including dedicated GPRS + default GPRS + EDAP channels) in one PCU, 204
of which can be EDAP channels.</p>
</li>
</ul>
</li>
<li><p>RNW restrictions:</p>


<ul>
<li><p>The maximum number of DAPs / BSC is
470.</p>
</li>
<li><p>The theoretical maximum number of TRXs
/ DAP is 20. However, since TRXs using DAP resources must be allocated to
the same Abis ETPCM line with EDAP, the maximum TRX count for a DAP is 12
in the ETSI environment and 8 in the ANSI environment.</p>
</li>
<li><p>Each BCF must have a unique DAP pool.</p>
</li>
<li><p>The serving PCU must be the same for
all TRXs under one segment (also including possible DAPs attached).</p>
</li>
<li><p>DAP + TRX signalling link + TCHs must
be located on the same ET-PCM.</p>
</li>
<li><p>The traffic and signalling timeslots
including the dynamic pool for each TRX must be located in one 2Mb frame and
cannot be shared with other 2Mb Abis frames.</p>
</li>
<li><p>When cross-connecting the 2Mb frame
containing the DAP and TRX tied to it towards the BSC, it is recommended to
make the connections either as a single PCM or as a n*64k TSL connection,
so that the transmission equipment complying with the G.796 standard will
maintain the octet sequence integrity of the TSLs carrying the DAP and TRX
traffic.</p>
</li>
</ul>
</li>
</ul>
</div>


<a name="nov2641711341" shape="rect"></a>
<div class="topic">
<h2>Benefits of Dynamic Abis</h2>

<p>The Dynamic Abis transmission feature saves up to 60 percent of the
Abis transmission expansion cost, since it allows Abis dimensioning to be
performed closer to the average data rates instead of at peak rates. This
also applies to the reduced number of 2M <a href="NED?action=retrieve&amp;identifier=general_glossary&amp;edition=13&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=id04439#id04439" onclick="openSmallPopup(event,'NED?action=retrieve&amp;identifier=general_glossary&amp;edition=13&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=id04439#id04439');return false" shape="rect" target="_blank">BSC</a> interfaces
needed.</p>


<p>The implementation of the Dynamic Abis pools is supported by Nokia's
cellular transmission products and can be performed with the NetAct Transmission
Planner tool.</p>
</div>


<a name="oct1441543182" shape="rect"></a>
<div class="topic">
<h2>Requirements</h2>

<p>Dynamic Abis is supported by Nokia UltraSite and MetroSite EDGE BTSs.
In addition, EDGE-capable TRXs are required.</p>
</div>


<a name="oct1441518201" shape="rect"></a>
<div class="topic">
<h2>Interoperability with other SW products</h2>

<p>Dynamic Abis cannot be used together with ISDN Abis because the DAP
timeslots cannot be connected via ISDN connections.</p>


<p>An implementation of (E)GPRS with Dynamic Abis should not be used together
with Satellite Abis due to delays in the satellite connections.</p>
</div>


<a name="dec1821044013" shape="rect"></a>
<dl class="note-notification">
<dt class="note-caption">Note</dt>
<dd>In phase 2, a more effective sub-timeslot usage of the
dynamic pool might be possible where the size of the pool can vary between
the given limits, and the more exact usage of the sub-timeslots might be possible.</dd>
</dl>


<a name="dec284140103" shape="rect"></a>
<div class="topic">
<h2>Dynamic Abis Enhancements</h2>

<p>Dynamic Abis Enhancements, introduced in BSS11.5, improves the performance
of Dynamic Abis allocation by modifying the BSC's internal resource allocation
procedures and algorithms, including PCU and EDAP resources. It enhances the
handling of failures during PSW territory upgrades.</p>


<p>Dynamic Abis Enhancements is an operating software and it is activated
automatically when Dynamic Abis is enabled.</p>
</div>


<a name="dec5291851" shape="rect"></a>
<div class="topic">
<h2>Related
topics</h2>

<ul>
<li><p><a href="NED?action=retrieve&amp;identifier=dn02263232&amp;edition=5&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=dec18218253220#dec18218253220" onclick="sync(this);return true" shape="rect">EGPRS transmission
planning</a></p>
</li>
<li><p><a href="NED?action=retrieve&amp;identifier=dn02242662&amp;edition=5&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=nov22215133515#nov22215133515" onclick="sync(this);return true" shape="rect">Overview of Nokia EDGE</a></p>
</li>
</ul>
</div>
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