SDCCH Drop During Location Update !!

[PaleNxtTel]

Dears ...

I have a problem in the SDCCH Drop in E******* equipment. More than 50% of the SDCCH Drop due to Drop During Location Update. I reduced the coverage area but no results. I tried to play with the CRO and CRH but no effect and still the same issue. The transmission is clear and no HW fault. Could this be related to signaling ? or related to core ? any idea ?


Thanks,

[electron]

Hi,


Do not you have lac island on this cell/site?


Cheers

Dears ...

I have a problem in the SDCCH Drop in E******* equipment. More than 50% of the SDCCH Drop due to Drop During Location Update. I reduced the coverage area but no results. I tried to play with the CRO and CRH but no effect and still the same issue. The transmission is clear and no HW fault. Could this be related to signaling ? or related to core ? any idea ?


Thanks,

[Jerry]

SDCCH congestion may cause the LU failed. Check if it is there.

[PaleNxtTel]

Hi Electron,

what do you mean by "LAC Island" ?

Hi,


Do not you have lac island on this cell/site?


Cheers

[PaleNxtTel]

Hi Jerry,

There is no congestion in the infected cells.

SDCCH congestion may cause the LU failed. Check if it is there.

[chronix_ray]

Hi,

I am also having this same issue. The location update is increased without doing anything any my SDCCH drops increased also. What should I do or check?

Br//

[luganomu]

PalexNxTel

Hw alarm to check if problem is on some cells
1.RF performance alarm
2.VSWR
3. RX cable disconnected

Apart from Alarm please do the following
1. LAC audit- make sure you clear all the planning mistake like
i] introducing one site with different lac with nearby site
ii] Site in improper BSC
2. LAC border review

You should check if the top worst cells in CLUNDROP are either BSC border/ LAC border. remember one BSC can have more than one LAC
BR

[Osman Nayeem]

Dear,

I just want to share something from my experience:

1. SDCCH Drop during LAC update is always close or more than 50% in E/// system in normal situation.
2. If the Cell is in LAC border, shift all the SDCCH TS to CHGR0, you will find good improvement.
3. Please check ICM band for any interference issue.
4. If the cell is not in LAC border, please check the drop rate for each SD TS from MOTS data. And then shift the SDCCH with better performing channel group.

Thanks!

[Optimustron]

Hi, I experienced from 2 or 3 years before that issue like Osman tell you, but some times it's hard to solve, I checked it out all things he mentioned and sometimes it works, i.e. move SDCCH's to CHGR0 and you see immediately the change in performance for SDCCH DROP RATE. At this time I have a sector that is far away from our location that is having this issue and I made all the possible changes to solve the problem, I'll keep trying to solve this and if we finally resolve this problem I'll tell you. By the way try the procedure from Osman because almost all the time it works, Best regards,

[Optimustron]

Hi friends, I finally have good news about the case I told you, almost at the end I reduced the coverage of the sector putting more downtilt to that sector but It did't work then I check again the KPI's, I see that the reasons of SDCCH DROP was "OTHERS", I only have 3 normal reasons, Excesive TA, Low Signal and Bad Quality I don't have the CLUNDROP from the new versions of BSS, then I check the entire parametrization of the sector and I found that somebody put a very high value of ACCMIN and of course BSRXMIN and MSRXMIN, the valuas was 75 for ACCMIN and MSRXMIN and 78 for BSRXMIN, I suspected that these values caused the SDCCH DROP then in despite of the high traffic of the sector I changed it to 90 and voila it works very well. Please check it maybe it's the same case or you can increase the power if you can because is almost the same that changing the ACCMIN to lower values. Best regards,