IRAT Failure: Returned to old physical channel

[ritgail]

Hi,

In our network we have faced a serious IRAT failure issue. the counter returned to old physical channel pegging is proportional to the irat failure. After doing GPEH analysis, we found out that it is cause mainly by iPhone5. Vendor is E*******.
Also, in a single UE context there is multiple failure, UE returning to 3G before timer expires for IRAT HO to 2G.

Does someone has some insight about it?

Thanks

[fon909]

Could you please confirm whether IRAT failures is dominant in CS or PS or both?

[ritgail]

We are concerned about CS, IRAT for PS call is disabled.

[babak1349]

Hello,
as far as I know in order to disable the Inter-RAT handover for specific RAB type you have to disable gsmHoAllowed in UeRc Am I right? But as default it is enabled So you need to check if for all RAB type except for CS call , it is disabled
So could you please check the value of the following counters:
pmNoOutIratCcReturnOldCh
pmNoFailOutIratHoSpeechReturnOldChPhyChFail

Please note IRAT Failure doesn't mean Drop call, the UE may come back to Original WCDMA cell. Returning to original cell can happen due to different problems:
1) Radio condition
2) HW problem in GSM cell
3) in concentric cell it may happen as the UE can be assigned to upper layer


please note pmNoFailOutIratHoSpeechReturnOldChPhyChFail also includes Multi-RAB which have speech
So you have mainly problem with Iphone which normally have PS connected So that's why I asked to check UeRc as well

Cheers

We are concerned about CS, IRAT for PS call is disabled.

[m121]

Hi, has someone managed to solve this iPhone 5 issue? We are also facing the same issue (Vendor NSN).

[khaldounh]

Hi, we are facing the same issue on Irat failure revision to old channel with Iphone 5 , E******* vendor. One IMSI tries 20 times on the same 2G cell even with parameter gsmAmountPropRepeat is set to 1.

[electron]

Check CIPHERING algorithm consistency in both 2G and 3G nodes

Hi, we are facing the same issue on Irat failure revision to old channel with Iphone 5 , E******* vendor. One IMSI tries 20 times on the same 2G cell even with parameter gsmAmountPropRepeat is set to 1.

[khaldounh]

Hi, It is not related to Ciphering issue, i have checked this, where did you observe this issue of Iphone 5, on which county? for me it is observed in Lebanon

[tharinduwije]

Did anyone find out a solution for this?

[khaldounh]

Did anyone find out a solution for this?

I remember that Huawei already provide a solution for this and I believe somebody in this forum has posted the solution which was in the MSC side.

Cheers

Khaldounh