Inter RAT HO Preparation Success (UTRAN with SRVCC)

[ank707]

Hi Guys,

We are having poor value of the KPI RNC_6106a ( Inter RAT HO Preparation Success UTRAN with SRVCC) in our Network. We have feature LTE3290 (SRVCC delay timer) on the RAN side and RObust SRVCC (E******* Core) activated. Pre-alerting is supported.

Delay timer value on the RAN as well as Core side was optimised with quite high values as well but no impact was seen. Can anyone guide me if the timers on the MME side can help such as srvccPsToCsComplete timer or SRVCC RESPONSE OR ACK MESSAGE.

Appreciate your help.

[djordjebeg]

Hi Guys,

We are having poor value of the KPI RNC_6106a ( Inter RAT HO Preparation Success UTRAN with SRVCC) in our Network. We have feature LTE3290 (SRVCC delay timer) on the RAN side and RObust SRVCC (E******* Core) activated. Pre-alerting is supported.

Delay timer value on the RAN as well as Core side was optimised with quite high values as well but no impact was seen. Can anyone guide me if the timers on the MME side can help such as srvccPsToCsComplete timer or SRVCC RESPONSE OR ACK MESSAGE.

Appreciate your help.
Hi ,

check this out

I have thoroughly checked the traces only to confirm that there is no abnormality in any of them. Each and every SRVCC from LTE to WCDMA is successful but the counter is still incremented. No abnormality is found from the internal logs of the automatically collected snapshots, either.

I then searched for similar cases again to see if such an issue has recently been reported by others. It has not. I did find one very similar case but it was an UE issue which is not your case (I have verified it from the logs).

Then I looked into the internal description of counters (which I already did at the very beginning) just to find that the M8006C273 counter definition has recently been updated with the highlighted note below:

Note: In case in the network environment there is an E******* MME used the counter is erroneously pegged when E-RABs are not admitted with a cause 'successful-handover', but in fact in the "E-RABs to Release List" IE of the S1AP:HANDOVER COMMAND message they were accepted by the MME.

file:///C:/Users/DJ8A05~1.BEG/AppData/Local/Temp/msohtmlclip1/01/clip_image001.jpg
so it is up to E/// and seems false triger...

[ank707]

Thanks Man. Can you please post the image again as it is not visible ? And which version are you referring to ? Untill LTE19a , there is no mention of this note. So which version is this ?

And my bad...something I forgot to mention. This degradation in LTE6106a (Inter RAT HO prep UTRAN with SRVCC) started after they started to activate Robust SRVCC in the E******* MMEs

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[djordjebeg]

Hello,
sorry for answering lately. we are using FL19B sw .
I hope picture is visible now.

Br,



file:///C:/Users/DJ8A05~1.BEG/AppData/Local/Temp/msohtmlclip1/01/clip_image001.jpg

[ank707]

It is still not visible. Are you using the "insert image" option ?
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