what happened?

**mhut** · 2012-07-17, 10:59 PM

I'm working with 2G alcatel. I have a problem. After I change BCCH frequency for some cells, the traffic of these cell decrease very strongly (from 45Erl/day to 1 Erl/day), MS can't camp on these cells when you use tems to lock BCCH frequency of these cells, however you can still handover to these cells.
Please share me your experience for this case.
Thanks!

**Finetopix** · 2012-07-17 10:59 PM

**banisha** · 2012-07-18, 08:39 PM

Maybe you have interference/jammer on BCCH frequency you are changing to.

**chefo** · 2012-07-18, 09:11 PM

Check the following:

cell/site alarms;
cell status - "cell barred"?
Immediate Assignment Success Rate;
LAU/RAU SR if on LA/RA border;
SDCCH performance;
Correct cell configuration in the MSC?

what happens when you lock to BCCH in TEMS?

when you HO to this cell, what's the RxLev and RxQual?

**usama0795** · 2012-07-19, 03:32 PM

more probably external interference; check share of UL quality HOs when u change the frequecy and if they are high then need specturm analysis test to detect the source of interfernce.....

**jan74** · 2012-07-19, 05:09 PM

Originally Posted by mhut

I'm working with 2G alcatel. I have a problem. After I change BCCH frequency for some cells, the traffic of these cell decrease very strongly (from 45Erl/day to 1 Erl/day), MS can't camp on these cells when you use tems to lock BCCH frequency of these cells, however you can still handover to these cells.
Please share me your experience for this case.
Thanks!

Check your neighbour definitions are correctly defined and check you don't have 2 neighbours with the same BCCH/BSIC. It sounds obvious but sometimes neighbour definitions are overlooked when changing BCCH.

**usama0795** · 2012-07-19, 06:30 PM

dont think the problem is with neighbor definition he said they checked in TEMS and MS cannot camp on Idle mode.....problem must be with UL Quality since neither of the Timeslots would lie within interence band 1 to 5 resulting in the radio to become inhibited.....check the values of inter_band 5 for the cell and make it 63 then go into the field again to check if MS camps on the cell or not.....

**zloy_qwer** · 2012-07-19, 09:18 PM

Mhh, you mean, that you can go to this cell by handover and cannot registeg under this cell?
Problem in registration procedure. please check if MSC have GCI of this cell.

make sure that no any cell have same bcch.
Just try to restart those cells if nothing help.

**mhut** · 2012-07-19, 11:28 PM

Thanks all for your support.
I told that all paramerters is the same after I change BCCH. So that I exclude paramerters problem (cell bare, CGI in MSC...).
when I plan new BCCH for this cell I checked co-BCCH, BSIC so that this cell and neighbour or 2 neighbours don't have the same BCCH-BSIC.
I think the problem may be:
registration procedure because MS can HO to this cell but not register in this cell. I wil reload data for this cell.
or
External interference because cell have many drop call due to UL quality, I see that BCCH frequency is bad so that I changed BCCH. However cell still has many drop calls due to UL quality after I change it. I don't know how to find the source of this interference.

Today I met some cases need your help:
Case 1: Cell define enough and right relation incoming and out going, however MS can HO from other cell to this cell but can't not HO from this cell to other cells until drop call happens.
Case 2: In idle mode, I lock BCCH of the cell (A), MS will camp on cell A, rxlev is good (-38dBm) and I can make call normally. However when I unlock BCCH of cell A, if MS reselection to other cell (B), MS don't measure cell A (I don't see cell A on measurement report although cell A has very strong rxlev and very near cell A; cell A was define neighbour of cell B)

**Mdaf** · 2012-07-21, 12:24 PM

Hello,
Check ncc PLMN allowed, as u have mentioned cell is not being reported which indicate that the BSIC of this cell is out of the ncc permitted.
Put it 255 to report all BSIC.
secondly have you used a new BSIC range?

Originally Posted by mhut

Thanks all for your support.
I told that all paramerters is the same after I change BCCH. So that I exclude paramerters problem (cell bare, CGI in MSC...).
when I plan new BCCH for this cell I checked co-BCCH, BSIC so that this cell and neighbour or 2 neighbours don't have the same BCCH-BSIC.
I think the problem may be:
registration procedure because MS can HO to this cell but not register in this cell. I wil reload data for this cell.
or
External interference because cell have many drop call due to UL quality, I see that BCCH frequency is bad so that I changed BCCH. However cell still has many drop calls due to UL quality after I change it. I don't know how to find the source of this interference.

Today I met some cases need your help:
Case 1: Cell define enough and right relation incoming and out going, however MS can HO from other cell to this cell but can't not HO from this cell to other cells until drop call happens.
Case 2: In idle mode, I lock BCCH of the cell (A), MS will camp on cell A, rxlev is good (-38dBm) and I can make call normally. However when I unlock BCCH of cell A, if MS reselection to other cell (B), MS don't measure cell A (I don't see cell A on measurement report although cell A has very strong rxlev and very near cell A; cell A was define neighbour of cell B)