LIST OF CRITICAL ALARMS

1000 LAPD OML Fault

DESCRIPTION:

The data link layer protocol between the BSC and the BTS is the LAPD protocol. To enable the communication between the data link layers of the BSC and the BTS through the LAPD protocol, the LAPD link should be established. The link carries operation and maintenance information is called OML, or LAPD_OML. This alarm is generated when the BSC detects the LAPD_OML disconnection between the BSC and the BTS or the BSC detects that the handshake with the BTS times out.

Impact on System

All the BTS services are disrupted when the LAPD_OML is disconnected. Fifteen minutes after the LAPD_OML is disconnected, the corresponding BTS

will be reset automatically.

Possible Causes

The transmission device or transmission link between the BSC and the BTS is faulty.

The Abis interfaced board of the BSC is faulty. The BTS experiences power failure. The TMU board or E1 lightning protection board of the BTS is faulty.

Handling Procedure

Check the Abis interface board of the BSC Rectify the fault according to the alarm help. After the trunk parent alarm is

cleared, check whether this alarm is cleared. Check whether the upper-layer BTS reports the following parent alarms Check the Abis interface board of the BSC Check the BTS power supply. Based on the Site No. carried in the alarm location information, check the E1

lightning protection board

405 Cell Out of Service

Description:

The BSC periodically checks the main BCCH TRX and the RSL of the main BCCH TRX. This alarm is generated when the RSL of the main BCCH TRX is faulty or the main BCCH TRX is unavailable for use.

Impact on System

The CS services and PS services of the out-of-service are disrupted.

Possible Causes

Manual block: The cell or BCCH TRX is manually blocked. Other OM operations: This includes manual reset of the BTS or cell, and

automatic BTS reset because of dynamic data configuration (for example, cell deactivation).

BTS power failure: There is power input for the BTS. Other causes: The BTS is unavailable for use for a short period because the LAPD

links or TRX attributes are adjusted; the BTS is reset because of the BSC reset; the BTS is automatically reset; the board is faulty; transmission failure occurs; the data configuration is improper; the BTS boards are reset manually.

Handling Procedure

Check the value of the parameter "out-of-service" in the alarm location information

If the parameter value is "1=other OM operations", check whether operations associated with the reset of the BSC or BTS is performed on the LMT by choosing BSC Maintenance > Maintain Logs > Query Operation Logs Online in the thirty minutes. You can also consult the maintenance personnel to check whether dynamic data configuration is performed.

o If the parameter value is "0=manual block", o If the parameter value is "2=BTS power failure",o If the parameter value is "3=other causes",

Check the loop status of the port and timeslot that carry the RSL of the main BCCH TRX

Check the cell and the main BCCH TRX of the cell. Check the BTS power supply.

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.

Impact on 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.

Handling Procedure

Check whether the primary BCCH is idle after the BCCH mutual aid. Check whether the original primary BCCH is idle. Check the original primary BCCH TRX for alarms. 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. Analysis of the alarm handling. If the BCCH mutual aid occurs because of hardware failure,a 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.

12830 Level 1 VSWR ALARM

Description

This alarm is reported when the VSWR is greater than 1.5.

Impact on System

When the alarm is generated, the output power of the antenna is reduced and the coverage area is reduced.

Possible Causes

The resistances of the antenna system are not matched. The forward and inverse power detection channel parts are faulty or the VSWR is

abnormal due to certain discrete parts. The BTS3900E has interference because of strong signals in the environment. The performance of the antenna system or the duplexer deteriorates.

Handling Procedure

Reset the BTS3900E module. Check whether the alarm is cleared. Check whether the connections between the BTS3900E antenna port and the

antennas are normal Measure the VSWR by using the related instrument at the antenna port. Locate

whether the fault occurs on the jumper, surge protector, feeder, TMA, or the antenna.

12846 E1/T1 Local Failure Alarm

Description

This alarm is reported when the BTS3900 does not receive the correct E1/T1 input signals, which leads to BTS transmission interruption.

Impact on System

When the alarm is generated, the BTS fails to provide services properly, which leads to cells of the BTS out of services, call drops, and handover failures.

System Actions

If the fault due to broken Abis transmission links is not rectified within 15 minutes, the BTS reset is triggered.

Possible Causes

Transmission links over the Abis interface are faulty. Transmission links between the BTS and the BSC are faulty.

Handling Procedure

1. Check the DIP switch2. Check the transmission links of the BTS.3. Check the transmissions at the peer end.

12848 E1/T1 Remote Failure Alarm

Description

This alarm is reported when the E1 chip of the peer equipment does not receive the correct input signals, which leads to BTS transmission interruption.

Impact on System

When the alarm is generated, the BTS fails to provide services properly, which leads to cells of the BTS out of services, call drops, and handover failures.

System Actions

If the fault due to broken Abis transmission links is not rectified within 15 minutes, the BTS reset is triggered.

Possible Causes

The connection of transmission links is abnormal. The BTS hardware is faulty.

Handling Procedure

1. Check the DIP switch on the panel of the BTS3900E.

2. Check the transmission links of the BTS.3. Check the transmissions at the peer end.