Handover between two cells that have same BCCH?!

**Areej** · 2012-05-15, 01:36 AM

Hi all,

I am facing a strange case .
working in Huawei vendor, I found 2 handover failures from cell A with (BCCH :72 / BSIC : 5-3) to cell B with (BCCH : 72 / BSIC : 4-3) , I checked if this is fake and searched if cell B is on air and I founded it serving in a near place !!

could that ever happen ?! a HO command between 2 cells that have same BCCH ?!

I am using Actix in my post analysis , could it be a problem in Actix itself or what?

Thanks

**ninjafine** · 2012-05-15, 02:38 AM

Hi! Please follow this discussion with the same question.
http://www.finetopix.com/showthread.php?11820-Same-BCCH

**Areej** · 2012-05-15, 02:51 AM

Thank you , but the thread is closed and my case is different as Iam talking about 2 cells not 3.

**Masood Jan** · 2012-05-20, 07:56 PM

the basic is different so handover will occur

**tremalnike** · 2012-05-20, 11:22 PM

There is noting interesting to discuss about this case. Change BCCH freq - this is the mandatory if two cells are nearly located ! If you can't do that due to contract clause, just adjust HO margin in order to made HO between cells quick as possible. Also you can adjust tilts, in order to made overlap zone smaller.

The reason for problem is:
in border area Cell1 -> Cell2, cell two cause too high interference and MS served by Cell 1 cannot decode HO command.

**Areej** · 2012-05-21, 12:37 AM

Thank you tremalnike for your answer .. I was just asking if that case is possible or I have a problem in my analysis tool.
btw , I am working as an analyst only so I don't have access on the network I just find the problems in logfiles and investigate them and then the report goes to higher engineer that is why I was asking about the possibility of the case only .

sorry if you find the topic not interesting !!

**s52d** · 2012-05-21, 02:05 AM

Hi!
Yes, it is possible: and it is not very big problem.
Let us assimue you have two neighbor cells unsing same BCCH and different BSIC.
There is a region where BCCH is not decodable: but maybe some other is clear, so idle mode works.

For calls using TCH on BCCH TRX this is problem, but if you are hopping over other TRXes, then handovers are fine:
once terminal detects new cell, handover is OK as hopping call is not interfered by BCCH.

Of course, we try to avoid it, and we all know terminals have problems with reporting correct BSIC once you
have two BCCHs too close.

But to answer your question: yes, it works, and consequencies are not as severe as some people feel.

BR
s52d

**electron** · 2012-05-21, 02:20 AM

Originally Posted by s52d

Hi!
Yes, it is possible: and it is not very big problem.
Let us assimue you have two neighbor cells unsing same BCCH and different BSIC.
There is a region where BCCH is not decodable: but maybe some other is clear, so idle mode works.

For calls using TCH on BCCH TRX this is problem, but if you are hopping over other TRXes, then handovers are fine:
once terminal detects new cell, handover is OK as hopping call is not interfered by BCCH.

Of course, we try to avoid it, and we all know terminals have problems with reporting correct BSIC once you
have two BCCHs too close.

But to answer your question: yes, it works, and consequencies are not as severe as some people feel.

BR
s52d

In dense area which site to site distance is less this sever will be more than expectation since FACCH decode success rate will decrease