401 BCCH Mutual Aid in a Cell

Description

This alarm is reported when the primary BCCH is switched to another TRX because the TRX carrying the primary BCCH is faulty. The BCCH mutual aid ensures that the disrupted services in a cell are restored within a short period of time.

Attribute

Alarm ID	Alarm Severity	Alarm Type
401	Major	Event

Parameters

ID	Name	Meaning
1	Cell Index.	Index of the cell where BCCH mutual aid occurs.
2	Cell Name	Name of the cell where BCCH mutual aid occurs
3	Cell CGI	Cell Global Identifier of the cell where BCCH mutual aid occurs
4	Site No.	Number of the site where the cell generating an alarm is located
5	Site Name	Name of the site where the cell generating an alarm is located
6	Alarm Attribute	0=Normal, Alarms period are longer than the Transient Threshold. 1=Transient Count, The times and the period of the alarms whose periods are shorter than the Transient Threshold are summed up. If the sum result is longer than the Alarm Occurrence Period Threshold or Alarm Occurrence Times Threshold, an alarm so called Transient Count Alarm is triggered. Because Transient Count Alarm is based on accumulative result, the recovery of the alarm may occur at least one Summing Cycle later. The Summing Cycle can be query by MML "LST STATSLDWIN".

Impact on the System

When the cell is re-initialized, the traffic over the cell resume normal operation after being disrupted for no more than 10 seconds.

System Actions

When this alarm is reported, the system detects available TRXs in this cell and selects one as the new primary BCCH TRX. The system assigns the primary BCCH to this TRX and reinitializes the cell. A switchback occurs under the following situations:
The former TRX carrying the primary BCCH is restored.
The management status of the primary BCCH is Unblocked.
TRX Aiding Function Control is set to Allowed Recover Immediately.

Possible Causes

The TRX carrying the primary BCCH is unblocked manually.
The primary BCCH is unblocked manually.
The TRX carrying the primary BCCH is faulty because of a hardware failure of the primary BCCH TRX.

Procedure

Check whether the primary BCCH is idle after the BCCH mutual aid.
Y=> The primary BCCH is idle. The BCCH mutual aid is successful. Go to 2;

N=> The Primary BCCH is not idle. The BCCH mutual aid fails. Another BCCH mutual aid occurs. If no other available TRX exists, contact Huawei Customer Service Center, and replace the faulty TRX.
Check whether the original primary BCCH is idle.
Y=> The primary BCCH is idle. Go to 3;

N=> The primary BCCH is not idle. Go to 4.
Check the original primary BCCH TRX for alarms.
Y=> The alarm is generated. Go to 5;

N=> The alarm is not generated. Go to 4.
View the status of the TRXs or channels, and check whether the BCCH mutual aid is caused by the manual blocking of the BCCH TRX.
Y=> The BCCH mutual aid is caused by the manual blocking of the BCCH TRX. The alarm handling is complete;

N=> The BCCH mutual aid is not caused by the manual blocking of the BCCH TRX. Contact Huawei Customer Service Center.
Analysis of the alarm handling.
If the BCCH mutual aid occurs because of hardware failure, replace the faulty TRX;

If the TRX board is not securely inserted or the connection between the power cables of the TRX and the cabinet is improper, the communication between the TMU and TRX is abnormal. Power on the TRX again.