ALM-12826 Radio Link Abnormal Alarm

Description

This alarm is reported when the BTS detects continuous abnormal radio links. The following cases may lead to abnormal radio links: 1. Abnormal channel activation: The channel type or status of the BSC is inconsistent with that of the BTS. 2. Abnormal channel release: The ratio of abnormal radio channel release exceeds the alarm threshold. 3. Warning alarm of no traffic on the main BCCH: No traffic is detected on the main BCCH within the continuous detection period. The period is four hours by default can be set as required. 4. Imbalanced uplink and downlink levels: The uplink RX level measured by the BTS and the downlink RX level reported by the MS differ greatly.

Attribute

Alarm ID	Alarm Severity	Alarm Type
12826	Warning	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:Warning of abnormal channel activation 1:Warning of abnormal channel release 2:Warning of no traffic on the main BCCH 3:Warning of imbalanced uplink and downlink levels
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	Cause of the Fault	Cause of the fault 0:warning for abnormal channel activation 1:warning for abnormal channel release 2:warning for no traffic on main BCCH 3:warning for power level imbalance between UL and DL

Impact on the System

Warning for abnormal channel activation (sub-category 0)
The BTS fails to respond or has no respond to channel activation. In this case, call failures occur and traffic measurements are affected.
Warning for abnormal channel release (sub-category 1)
When the uplink or downlink link is faulty, proper interaction cannot be implemented on the radio interface. After channel activation, this channel fails to perform normal communication on the Um interface, which leads to release of the channel by the BSC.
Warning for no traffic on the main BCCH (sub-category 2)
Access or handover to this cell does not occur.
Warning for power level imbalance between uplink and downlink (sub-category 3)
When the uplink RX channel or downlink TX channel of the BTS is faulty, the traffic measurements are directly affected.
If the downlink TX channel of the main BCCH is faulty, the coverage and traffic of the cell are reduced.
If the downlink TX channel of the non main BCCH is faulty, the coverage of the BTS is reduced. If the channel is assigned to this BTS, the assignment failure may occur and handover success rate is lowered.
If the uplink RX channel of the main BCCH is faulty, within the coverage of this cell, MSs can have signals but fail to make calls. Therefore, traffic is reduced and handover success rate is lowered.
If the uplink RX channel of the non main BCCH is faulty and the channel is assigned to this BTS, the assignment failure may occur and handover success rate is lowered.

System Actions

The system starts auto detection after the alarm is generated. The alarm will disappear when the conditions are met.

Possible Causes

The channel types or channel states between BTS and BSC are not consistent.
The proportion of abnormal channel release exceeds the relevant alarm threshold.
There is no traffic detected on the main BCCH within the set period.
The BTS detects that the UL power level and the DL power level deviate from each other greatly.

Procedure

Check the channel configuration of the main BCCH.
Check whether the main BCCH is configured with the TCH channels.

Y => Go to procedure 2.

N => Check whether the TCHs are converted to the PDCHs. If yes, the alarm handling is complete. If not, go to procedure [2].
Originate a call through the main BCCH.
Lock the frequency of the test MS to the frequency of the main BCCH and originate a call. Check whether the alarm is cleared:

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

N => The alarm is not cleared. Go to procedure 3.
Reset the BTS.
Reset the Site in Level 4 on the BSC or the LMT. Check whether the alarm is cleared.

Y => The alarm is cleared. No further action is required.

N => The alarm is not cleared. Go to procedure 4.
Replace the BTS3900E module.
Replace the 3900E Module that is faulty. Check whether the alarm is cleared.

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

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