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call drop analysis

Publication Date:  2016-04-26 Views:  633 Downloads:  0
Issue Description
Australia custom use our GSM-R solution for their railway, but in the test ,there have a call drop issue
Alarm Information
BTS have no alarm, BSC have no alarm also
Handling Process

Oatly Call Drop analysis

From the trace, we can see the PTP call setup successfully, the user’s TMSI is AC907E89:

Suddenly, the uplink RXLev/RXQual became -110/7 at 13:55:10(560),after fourteen measure reports time, BTS set connection failure , then call drop. Before 13:55:10(560), the RXLev and RXQual is very good. So, first, we can eliminate the radio environment reason.

During the poor RXQual time, another Channel Required message received in this cell, it means the BTS is working  normal. So we can the eliminate the network’s reason:

 also we can see,  the Cab Radio raised a Location Updating process after the call drop,, the LU type is imsi-attach, that means the Cab Radio was dropped from the network,  then it registering network again. The user’s TMSI is AC907E89,  it is the generation of dropped calls Cab Radio

So,based on the above analysis , this call drop was caused by the Cab Radio

We hope Funkwerk can continue  analysis in the further and find  the root cause.Huawei would like give any support if Customers or Funkwerk need .

2Sydenham South Call Drop analysis

Root Cause: RXLev= -108dbm,Coverage is too bad

Root Cause
Cab Radio’s off  network caused  call drop

check the cab radio and replace a new one

In the GSM-R solution, it integrates many third-party equipment, when the issue happened,customer always asked us to help them to handle the issue. Because third-party equipment, we do not have the ability to deal it, narrow the scope of the exclusion and address the causes of our equipment to help customers deal with the problem is necessary