PS Drop Call after Cell Update Process (RIP Cause)

[aleon23]

Hi expert,

In my network I have experienced the next problem in PS Drop Call:
After UE changes from DCH to FACH, in FACH sate there are a lot Cell Update Request, some of them are response successfully, but 50% of them are not.
In the image you can see, Cell Update Request by UE, in this message there is information about (u_RNTI - srnc_Identity / s_RNTI), then RNC acknowledges the message by RRC Cell Update Confirm with new c-RNTI, but after this no response from UE, after send twice Cell Update there is a Iu Release with cause 14 (Failure in the Radio Interface Procedure).

Can you help me with ideas to find where the problem is.

Thanks in advance engineers!!

L3.png

CU.png

CUConfirm.png

[linhhy]

Could you give the log file? It's better for analysis

[aleon23]

Could you give the log file? It's better for analysis

Hi linhhy,

Attached you can find 2 log file, because the one of the images is based on another toold that I cannot export it.

Regards,

[linhhy]

Hi linhhy,

Attached you can find 2 log file, because the one of the images is based on another toold that I cannot export it.

Regards,

I dont see any issue with cell_FACH state. The problem comes frome cell_PCH. After UE changed to Cell_PCH, it had a lot of Cell Update caused by Cell reselection, and the system release UE out of Cell_PCH to Idle. Let me check Huawei algorithm for this issue and come back later.

[aleon23]

I dont see any issue with cell_FACH state. The problem comes frome cell_PCH. After UE changed to Cell_PCH, it had a lot of Cell Update caused by Cell reselection, and the system release UE out of Cell_PCH to Idle. Let me check Huawei algorithm for this issue and come back later.

Thanks for your reply linhhy,

Actually the problems are in FACH and PCH, exactly, with a lot cell update with cause "cellreselection", also all these fails are mapped random for all the network.

I appreciate for you kindly help.

I'll waiting for your answer!

Thanks in advance.

[linhhy]

Thanks for your reply linhhy,

Actually the problems are in FACH and PCH, exactly, with a lot cell update with cause "cellreselection", also all these fails are mapped random for all the network.

I appreciate for you kindly help.

I'll waiting for your answer!

Thanks in advance.

Sorry brother, I cant find real root cause for this case. But in the logfile I think it's not network problem. I may be cause from Smartphone UE, I mean UE initial release PS connection in cell_PCH to save power. (signallingConnectionReleaseIndicationCause: 0 ( uERequestedPSDataSessionEnd))

What's your vendor and what is release version? Do you have Enhanced Fast Dormancy Feature?

[aleon23]

Sorry brother, I cant find real root cause for this case. But in the logfile I think it's not network problem. I may be cause from Smartphone UE, I mean UE initial release PS connection in cell_PCH to save power. (signallingConnectionReleaseIndicationCause: 0 ( uERequestedPSDataSessionEnd))

What's your vendor and what is release version? Do you have Enhanced Fast Dormancy Feature?

The vendor is HW, R16, EFD actually enable man.

But it is a release from the system but after all these cellupdate, that is the strange in this case.

Regards

[linhhy]

The vendor is HW, R16, EFD actually enable man.

But it is a release from the system but after all these cellupdate, that is the strange in this case.

Regards

It's quite strange. I dont find any special event within DL-DCCH CellUpdateConfirm messeage, that indicate RRC dropped actually.