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<div class="div">
<h1>Radio Network Maintenance</h1>

<p>Radio network maintenance in the BSC provides facilities
for maintaining the operational status of the radio network system when faults
occur in the base station system (the BSS).</p>


<p>In addition to detection of faults in the BSS, the feature
includes automatic operations that minimise the effect of faults on the quality
of the service. The user is informed of these faults by alarm print-outs (alarm
reports).</p>


<a name="mar154148101" shape="rect"></a>
<div class="topic">
<h2>BTS
Alarm Handling in BSC</h2>

<p>The alarm handling system receives alarm indications from
the following sources in the radio network:</p>


<ul>
<li><p>Alarms from the BTS equipment</p>
</li>
<li><p>External alarms from the BTS site</p>
</li>
<li><p>Alarms concerning PCM lines in the
radio network</p>
</li>
<li><p>Alarms from LAPD links on the Abis
interface</p>
</li>
<li><p>Alarms from Abis interface equipment</p>
</li>
<li><p>Alarms from BSC application programs.</p>
</li>
</ul>


<p>The alarm handling system informs the user of the faults
by actual alarm print-outs. Moreover, the alarm handling system makes decisions
on the basis of alarm indications and activates the radio network recovery
when needed so that the automatic recovery actions are started.</p>


<p>When there are multiple fault indications, the alarm handling
system will attempt to eliminate all other fault indications except the actual
one. Other fault indications may be blocked if a more critical fault has arrived
and is still under process. This procedure is needed in case of alarm bursts.</p>


<p>With the MML interface, the user can:</p>


<ul>
<li><p>Block and unblock alarms &amp; list
blocked alarms</p>
</li>
<li><p>Change alarm class</p>
</li>
<li><p>Cancel alarm</p>
</li>
<li><p>List alarm currently on</p>
</li>
<li><p>List alarm history.</p>
</li>
</ul>
</div>


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<div class="topic">
<h2>BCF
Maintenance Mode</h2>

<p>The main idea of the feature is to provide a way to separate
a particular site from normal alarm surveillance. This makes it possible to
‘isolate’ a site, for example, which is having problems concerning subsequent
alarming or a site, which is still in the hands of commissioning/integration
teams.</p>


<p>The BCF maintenance mode allows the user to block or modify
the BTS alarm handling of a specified BCF. This can be done by MML commands.
The modifiable parameters are:</p>


<ul>
<li><p>RECOVERY</p>
</li>
<li><p>LOCAL PRINT-OUT</p>
</li>
<li><p>NetAct UPDATING</p>
</li>
<li><p>BLOCKED.</p>
</li>
</ul>


<p>The first three have the values ON and OFF. BLOCKED means
that all these functions are disabled, and alarms are not handled at all.</p>


<p>When recovery is disabled and then enabled with the MML,
the default action of the alarm system is to restart the BCF because some
recovery actions may have been lost during the maintenance mode.</p>


<p>When one or several parameters are in the state OFF, the
alarm "BCF MAINTENANCE MODE" is active.</p>
</div>


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<div class="topic">
<h2>BTS
Fault Recovery in BSC</h2>

<p>BTS recovery in the BSC minimises the effect of faults
in the radio network on the service level provided by the BSS. In addition
to performing fault originated recovery actions, the BTS recovery controls
initialisations when there are resets and restarts in the BSS radio network.
The latter includes phasing activities in software and configuration loading.</p>


<p>The type of recovery action depends on the type of the
faulty unit (for example, the FU or CU) and its current channel configuration.
When there are multiple recovery inputs, the BTS recovery system tries to
eliminate all other recovery requests except the actual one. The other recovery
requests can be blocked or ignored if a more crucial fault or initialisation
has occurred and is still underway.</p>


<p>After the faulty unit has been repaired or replaced, and
the operating personnel takes it back to use, or the system cancels the failure,
radio network configuration management allocates the related resources back
to call control purposes.</p>


<p>The BTS recovery system is activated in the following cases:</p>


<ul>
<li><p>DSP/TSL fault</p>
</li>
<li><p>TRX fault</p>
</li>
<li><p>BTS fault</p>
</li>
<li><p>Fault covers the whole BTS site</p>
</li>
<li><p>Failures in transmission network</p>
</li>
<li><p>TRX local blocking/deblocking</p>
</li>
<li><p>Initialisations (resets) in BSS radio
network</p>
</li>
<li><p>Restarts by user commands.</p>
</li>
</ul>
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