<?xml version="1.0" encoding="utf-8" standalone="yes"?><html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Dynamic Abis calculation method</title>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type" />
<meta content="text/css" http-equiv="Content-Style-Type" />
<script src="NED?action=retrieve&amp;identifier=dn00188761&amp;edition=1&amp;language=none&amp;coverage=global&amp;encoding=javascript&amp;component=data&amp;item=data" type="text/javascript" xml:space="preserve">
</script>
<?conversion name="Pub2XHTML" version="2.0" source="urn:mars:dn02263232:5:en:global:publishing_online_1_0:data:data:*:*:*" date="2005-02-21T13:13:48Z"?>
<link href="NED?action=retrieve&amp;identifier=dn01158124&amp;edition=1&amp;language=en&amp;coverage=global&amp;encoding=css&amp;component=data&amp;item=data" rel="stylesheet" title="Nokia Networks default online style" type="text/css" />
<meta content="draft" name="status" />
<?conversion name="SplitHTML" version="1.9" source="urn:mars:dn02263232:5:en:global:publishing_online_1_0:data:data:46:*:*" date="2005-02-21T13:13:48Z"?>
</head>
<body lang="en" xml:lang="en">
<p><a name="dec1721235114" shape="rect"></a>
<a name="ned_2" shape="rect"></a></p>

<div class="div">
<table width="100%">
<tr>
<td align="center" colspan="1" rowspan="1" width="20%"><?NED5 annotation?>
<br clear="none" /><?NED5 printview?>
</td>
<td align="center" colspan="1" rowspan="1" width="20%"></td>
<td align="center" colspan="1" rowspan="1" width="20%"></td>
<td align="center" colspan="1" rowspan="1" width="20%"><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=ned_1#ned_1" onclick="sync(this);return true" shape="rect">EGPRS transmission planning</a></td>
<td align="center" colspan="1" rowspan="1" width="20%"><a href="NED?action=retrieve&amp;identifier=dn02263232_about&amp;edition=5&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=ned_top#ned_top" onclick="openSmallPopup(event,'NED?action=retrieve&amp;identifier=dn02263232_about&amp;edition=5&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=ned_top#ned_top');return false" shape="rect" target="_blank"><img alt="Document information" border="0" class="Metainfo" src="NED?action=retrieve&amp;identifier=dn01158003&amp;edition=1&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /></a></td>
</tr>
</table>


<div class="div">
<h2>Dynamic Abis calculation method</h2>

<p>Use the Dynamic Abis calculation method to calculate the
transmission capacity on the Abis and Gb interface and to dimension the BSC
and SGSN capacities.</p>


<p>Before calculating the necessary transmission capacities
for Abis, Ater, and Gb interfaces, define the structure of the traffic by
dividing it into circuit switched traffic and the common and/or dedicated
packet switched data timeslots:</p>


<ul>
<li><p>The number of the allocated <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=id04070#id04070" 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=id04070#id04070');return false" shape="rect" target="_blank">TCH</a>s
in the radio interface must be defined separately for each traffic type before
calculating the required traffic for Voice, <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=id04656#id04656" 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=id04656#id04656');return false" shape="rect" target="_blank">CSD</a>,
and PSD.</p>
</li>
<li><p>The structure of the traffic mix is normally obtained from radio
frequency planning.</p>
</li>
</ul>


<p>The following parameters are required during the EDGE transmission
dimensioning process to calculate the capacities for the Abis, Ater, and Gb
interfaces.</p>


<ul>
<li><p>number of subscribers/BTS sector</p>
</li>
<li><p>total number of BTSs</p>
</li>
<li><p>number of BTSs/BSC area</p>
</li>
<li><p>number of TRXs/BTS</p>
</li>
<li><p>number of common and dedicated EGPRS
traffic channels/BTS </p>
</li>
<li><p>number of voice/CSD traffic channels/BTS</p>
</li>
<li><p>blocking rate of the radio interface
(for example, 1-2%)</p>
</li>
<li><p>blocking rate of the Ater interface
(for example, 0,1%)</p>
</li>
<li><p>packet size of the Gb interface (for
example, 512 bits)</p>
</li>
<li><p>used MCS rate (1-9)/BTS </p>
</li>
<li><p>throughput target of the radio interface
TCHs /Cell (kbps)</p>
</li>
<li><p>Dynamic Abis Pool overflow probability
(%) (Abis loss target)</p>
</li>
<li><p>size of the EDAP.</p>
</li>
</ul>


<p>When dimensioning non-real time traffic, maximum peak rates
are not normally required. The Abis interface can therefore be dimensioned
closer to the average data rates instead of peak rates, using the “Binomial
distribution” formula. With this formula, you can calculate the probability
of a successful call if you want to overdimension the transmission network
with the assumption that the radio interface is not fully loaded all the time.</p>


<p>Here, the basic idea is to compare the number of the radio
interface TCHs against the available/necessary timeslots in the Abis frame.
The value resulting from the calculation is the number of timeslots in the
Abis frame that are required to fulfill the given targets for pool overflow,
throughput, and used MCS rate. After the calculation, we know the Abis structure
and requirements for the cross-connection tables.</p>


<p>The timeslot allocation in the 2Mb frame must be known
before the Abis overflow and benefit of the pool can be calculated. The advantage
of the dynamic pool is the compromise of its configuration, blocking, throughput,
and usage of the pool. The calculation of the pool overflow/blocking requires
knowledge of the planned 2Mb -path system.</p>


<p>When defining the throughput target of the radio interface
TCHs (channel utilisation), take into account the following:</p>


<ul>
<li><p>re-transmission</p>
</li>
<li><p>buffering </p>
</li>
<li><p>possible link management</p>
</li>
<li><p>Q1</p>
</li>
<li><p>pilot bit timeslot in 2M PCM frame.</p>
</li>
</ul>


<p>The throughput target of the radio interface TCH is also
required for the BSC, SGSN, Gb interface, and for the core/Backbone Network
dimensioning.</p>


<p>We can calculate the Abis overflow (blocking) value when
we know the size of the pool and the number of the radio interface TCHs that
are competing for the usage of the pool. Only a low pool overflow (that is,
0,1%) should be allowed because the system should not be limited by transmission.</p>


<p>The theoretical probability of successful trials per each
call can be calculated with the binomial distribution formula, as shown below:</p>


<ul>
<li><p>B = Probability of pool overflow (blocking)</p>
</li>
<li><p>N =is the available pool size </p>
</li>
<li><p>p = is the channel utilisation of the EGPRS channels</p>
</li>
<li><p>n = EGPRS radio interface TCHs in use</p>
</li>
</ul>


<a name="dec18218372627" shape="rect"></a>
<div>
<img alt="urn:mars:dn02263295:1:en:global:tiff:data:data" border="0" src="NED?action=retrieve&amp;identifier=dn02263295&amp;edition=1&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /></div>


<a name="nov3041220445" shape="rect"></a>
<div>
<h6>Example</h6>



<p>The figure <em>Dynamic Abis pooling </em>
shows an example of Dynamic Abis pooling.</p>


<a name="jan941246302" shape="rect"></a>
<div>
<img alt="urn:mars:dn02242647:2:en:global:cgm_fixed:data:data" border="0" src="NED?action=retrieve&amp;identifier=dn02242647&amp;edition=2&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /><p class="figure-caption">Figure: Dynamic Abis pooling</p>
</div>



<p>To calculate the maximum size of the DAP you need to know:</p>


<ul>
<li><p>how many TRXs are connected to the chosen ET_PCM</p>
</li>
<li><p>what kind of signalling is used in the hosting BTSs.</p>
</li>
</ul>



<p>The example below shows an EDGE BTS 2+2+2 configuration,
with a throughput target of 32 kbps per radio interface TCH.</p>


<a name="dec18218293523" shape="rect"></a>
<div>
<img alt="urn:mars:dn02263268:1:en:global:cgm_fixed:data:data" border="0" src="NED?action=retrieve&amp;identifier=dn02263268&amp;edition=1&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /><p class="figure-caption">Figure: Traffic mix example of 2+2+2 EDGE BTS</p>
</div>



<p>In this case, we have reserved 12 TSLs from the pool with
the target to support 32 kbps throughput for EGPRS channels. The figure <em>Example of 2+2+2 EDGE having 18 air TCH against 12 TSL for EDAP
2</em> shows how the radio interface TCHs are inserted into the Abis frame. </p>


<a name="dec18218304824" shape="rect"></a>
<div>
<img alt="urn:mars:dn02263283:1:en:global:cgm_fixed:data:data" border="0" src="NED?action=retrieve&amp;identifier=dn02263283&amp;edition=1&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /></div>


<a name="nov2831454283" shape="rect"></a>
<div>
<img alt="urn:mars:dn02264325:4:en:global:cgm_fixed:data:data" border="0" src="NED?action=retrieve&amp;identifier=dn02264325&amp;edition=4&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /><p class="figure-caption">Figure:  Example of 2+2+2 EDGE having 18 Air-TCH against 12 TSL for EDAP
2 </p>
</div>
</div>
</div>
</div>
</body>
</html>