ALM-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.

Attribute

Alarm ID	Alarm Severity	Alarm Type
12846	Major	Fault

Parameters

ID	Name	Meaning
1	Site No.	Number of the site where the faulty board or module is located Value range: 0-2047
2	Board Type	Number of the type which the faulty board belongs to. 107:BTS3900E
3	Board No.	Number of the fault board 0-3: BTS3900E
4	PassNo	Number of the passage where the faulty board is located.
5	SubLink No.	Alarm sub-category number 0:E1 port No.0 1:E1 port No. 1
6	Cell Index	Index of the cell where the board or module is located 0-2047: Cell index of the faulty cell in the data configuration 65535: None
7	Site Type	Type of the site where the faulty board is located. 30:BTS3900E;
8	RackNo	Number of the rack where the faulty board is located.
9	BoxNo	Number of the subrack where the faulty board is located.
10	SlotNo	Number of the slot where the faulty board is located.
11	Site Name	Site Name
12	Alarm Attribute	Alarm Character 0:Normal 1:Transient Count
13	E1 Port Number	E1 port number 0:E1 port No.0 1:E1 port No.1

Impact on the 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.
The BTS3900E module is faulty.
The line coding configuration is incorrect.

Procedure

Check the DIP switch on the panel of the BTS3900E.
If the DIP switch is correctly set, check whether the alarm is cleared.

The DIP switch has four bits. Bit 0 and 1 are used to set the BTS/RRU mode, E1 unbalanced mode, E1 balanced mode, and T1 mode.

Bit 0 and Bit 1: 0 refers to the ON status and 1 refers to the OFF status.

If the BTS3900E is set to the E1 unbalanced mode, E1 balanced mode, and T1 mode, you can infer that the BTS3900E is in BTS mode.

The settings of Bit 0 and Bit 1 are as follows:

00: E1 unbalanced mode (75 ohms)

01: E1 balanced mode (120 ohms)

10: T1 mode

11: RRU mode

Y => The alarm is cleared. End the alarm handling.

N =>The alarm is not cleared. Go to procedure 2.
Check the transmission links of the BTS.
Perform the local self-loop on the RX and TX ends of the BTS and check whether the LIU LED on the panel is OFF.

Y=> The LIU LED is OFF. The transmission is recovered. Check whether the alarm is cleared. If yes, end the alarm handling. If no, go to procedure [3].

N=> The LIU LED is ON. Go to procedure 3.
Check the transmissions at the peer end.
Perform self-loop on transmission links from the BSC or upper-level BTSs and check whether the LIU LED of the E1 link at the peer end is OFF.

Y=> The transmission links at the peer end are normal. The cause may be the hardware faults.

Contact Huawei Customer Service Center.

N=> The transmission links at the peer end are abnormal. Repair the link and end the alarm handling.
Replace the E1 cables. Check whether the alarm is cleared.
Y=> The alarm is cleared. End the alarm handling.

N=> The alarm is not cleared. Go to procedure 5.
Replace the BTS3900E.
Replace the BTS3900E Module, and check whether the alarm is cleared.

Y=> The alarm is cleared. End the alarm handling.

N=> The alarm is not cleared. Contact the Huawei Customer Service Center.