what is the problem?

[mhut]

Dear all,
I have a problem which want every body discuss and share your experience.
As we know, SDCCH mean holding time is about 3-6s while TCH mean holding time is about 25-30s.
So that normally SDCCH drop rate is less than TCH drop rate.
Now in my 2g E******* network, SDCCH is higher than TCH drop rate, what is the problem?
Thanks!

[Handover24]

it is strange and it is not clear to me...so few particulars.
Add more details and maybe we could discuss better...

[mhut]

It happens on all BSC and have 40% number cell have SDCCH drop rate higher than TCH drop rate.
I caculated average SDCCH drop rate of this group cell is 1.2% while TCH drop rate is only 0.6%.
If you want any more information, I can provide.
Thanks!

[Handover24]

Do you have other counters which explain you the cause of SDCCH drop ?
Try to check them...is a drop during a location ? A MOC...an SMS sent ?
Regards

[mhut]

Do you have other counters which explain you the cause of SDCCH drop ?
Try to check them...is a drop during a location ? A MOC...an SMS sent ?
Regards
Hi friend,
80% SDCCH drop is CLUNDROP. So that Drop during location update is the main reason.

[Ahmed.]

So it means your cell is doing a lot of location updates. You need to check the following:

1. Check the MRR stats to see if the cell is serving far away (TA samples). Down tilt the cell if you feel its overshooting.
2. Check to see its HO pattern with the NBR cells of the other LAC (You may be able to judge where the overlap is the most).
3. Temporarily, try giving it a negative CRO (PT = 31). Also, change the CRH (re-selection hysteresis) of the the cells to which you suspect it is performing location updates.
4. Check your LAC plan, check the roads & everything. Maybe, it is in a slow busy road where it gets some ping pong re-selections. You may have to change it. (An example is the rail roads where there are massive LAC updates).

[Ahmed.]

Ok, so you are having high drops. Are the drops due to Low SS, excessive TA? I think the cell is overshooting & you may have to down tilt it. Is it a rural cell?

[bvelev]

I had similar problem two times and it was due to unsuccesful location updates. It was caused by a single faulty MS which couldn't register to the network.

[Optimustron]

I had similar problem two times and it was due to unsuccesful location updates. It was caused by a single faulty MS which couldn't register to the network.
We have this kind of problems then I moved the SDCCH from CHGR=x to CHGR=0 you know the command RLCCC:CELL=YYYYYYY,CHGR=x,SDCCH=0; then RLCCC:CELL=XXXXXXX,CHGR=0,SDCCH=4,TN=1&&4; for example, please check if the final number of SDCCH are well with command RLCRP and RXCDP, wait 5 minutes, the check again your SDCCHs, if it's not well then reduce by one the number of SDCCH from 4 to 3 for example and then put 1 to other CHGR, finally check your statistics, I see a drasctic reduction on SDCCH DROP rate in my network, I hope this works well for you, best regards,

[Shakeel_15]

Hello,

First of all do not correlate SD Mean holding time/TCH mean holding time with the SD Drop rate and TDR. They are two seprate KPI which caluclates failures over request. At leasr read it in details.

In your case SDR is high check the breakdiown either what bad coverage, quality and a you menioned location updates so do all optimization check and change the CRH parameters to more stronger values and see the impact.

BR

Dear all,
I have a problem which want every body discuss and share your experience.
As we know, SDCCH mean holding time is about 3-6s while TCH mean holding time is about 25-30s.
So that normally SDCCH drop rate is less than TCH drop rate.
Now in my 2g E******* network, SDCCH is higher than TCH drop rate, what is the problem?
Thanks!