High CS Call Drops in Metro Cell

**ejamhas** · 2015-01-20, 05:35 PM

Hi All,

I have very high CS Drops in the metro cells. Tried changing below parameters but very little to no improvement observed. Please tell me what else I can do.

2d, 2f parameter made more aggressive.
and RL Power for CS 12.2k increased.
neighbour optimization
Event1A and 1B speedup.
InterFreqRAT Switch changed from INTERFREQRAT to INTERRAT
CPICH is already max.

**Finetopix** · 2015-01-20 05:35 PM

**Boraa** · 2015-01-20, 08:00 PM

try to check the Macro covering the Metro

**ejamhas** · 2015-01-21, 07:01 PM

What to check in the Macro?

**samuraial** · 2015-01-21, 07:32 PM

Do a DT at that area and see the reason from the files.
You can do a CDT trace for the number it is making the DT and check that log also for more information.
Check RTWP in that cell also as it is related directly with the CDR.
See the statistics and see if this CDR was high since the time the site came on-air or started as some specific date.
If second check compare the parameters or see if any changes were made during that time.
Check alarms if any.

B/R

**yassanino** · 2015-01-23, 07:12 PM

is your drop ratio high is busy hour , try to analyse based on number of drops instead , a metro have a high mobility check your capacity 1st then SHO and ISHO params
more details are needed to find your RC
BR

**electron** · 2015-01-23, 10:56 PM

Originally Posted by ejamhas

Hi All,

I have very high CS Drops in the metro cells. Tried changing below parameters but very little to no improvement observed. Please tell me what else I can do.

2d, 2f parameter made more aggressive.
and RL Power for CS 12.2k increased.
neighbour optimization
Event1A and 1B speedup.
InterFreqRAT Switch changed from INTERFREQRAT to INTERRAT
CPICH is already max.

maybe it is happening due to some fast moving users and SHO happening late try to work on individualOffset parameter to maintain the call during mobility between 2 sector if it is hte case

Cheers

**kevin_h811** · 2015-01-24, 07:32 AM

Have you tried to check your Qqualmin...maybe too low...may cause High CS failures...

Originally Posted by ejamhas

Hi All,

I have very high CS Drops in the metro cells. Tried changing below parameters but very little to no improvement observed. Please tell me what else I can do.

2d, 2f parameter made more aggressive.
and RL Power for CS 12.2k increased.
neighbour optimization
Event1A and 1B speedup.
InterFreqRAT Switch changed from INTERFREQRAT to INTERRAT
CPICH is already max.

**shishio** · 2015-01-24, 05:57 PM

Originally Posted by ejamhas

Hi All,

I have very high CS Drops in the metro cells. Tried changing below parameters but very little to no improvement observed. Please tell me what else I can do.

2d, 2f parameter made more aggressive.
and RL Power for CS 12.2k increased.
neighbour optimization
Event1A and 1B speedup.
InterFreqRAT Switch changed from INTERFREQRAT to INTERRAT
CPICH is already max.

dear ejamhas,

call drops occur due to the following reasons;

poor rf conditions (poor rscp or ecno)
external interference (high rtwp)
hardware faults on nodeb or cell
transmission outages affecting nodeb
power system outages on nodeb
configuration setting errors

from what you have tried, i can see that you are basically focused on poor rf conditions and configuration settings, try checking out the other factors that can affect call drops esp transmission problems and external interference.

NB:setting your cpich to max in a metro area is a bad idea, you will cause the cells to overshoot and interfere with other cells (DL interferance, PSC clashes) this could even be the reason for your call drops, try not to exceed 33dbm for cpich if you are using 20w rru in the cell (rule of thumb is to use set cpich to 5-10% of total rru power)