Case27: Troubleshooting of HO fail because of wrong eNB-ID

1. Production:

4G Femto V1.7.0

2. Issue Description:

S1 HO failed between two femtocells. Both Femtocells should be HOME eNB.

In eNBConfigurationTransfer and HandoverRequired messages (frames 22, 23, 31,32) the target eNB-ID is sent as a MACRO eNB-ID instead of HOME eNB-ID.

Notes:  neighbourhood relations are not configured in advance in the 2 radios because we want to have the ANR based on mobiles measurements.

3. Issue Troubleshooting:

1- Captured the MME S1 log when trying to do HO.

2- download the device.xml and device.log for both femtos.

4. Root Cause:

The target cellid and TAI requested by the user are not recognized, this failure reason value is returned as follows:

5. Solution:

Because the enbType added by ANR is set to 0 by default.

For home eNB, it can be distinguished whether the newly added neighboring cell is a home enb or not by limited the Range:

Path: Device.Services.FAPService.{i}.SON.ANR

HomeEnbEarfcnRange: 1900..1930   //cuz we used 1925, the range should be set less than 100, so choose 1900..1930 for example.

Notes: If there are both macro and home stations in the environment, and the frequency selection is the same, then only one can be selected for HO. If HO with macro stations (type=0), the default configuration does not need to be changed. If HO with home stations, the range needs to be limited according to the above method, and the types within this range are all 1.

Troubleshooting Methods: Download