Co BCCH-TCH

[justdream]

Frineds,
can you tell me from your experience, what's the effect of having Co BCCH-TCH?
as all people here just care about Co BCCH-BCCH and Co TCH-TCH...

so pleas ehelp me to understand in more details the effect of Co BCCH-TCH????

[RF engineer]

Frineds,
can you tell me from your experience, what's the effect of having Co BCCH-TCH?
as all people here just care about Co BCCH-BCCH and Co TCH-TCH...

so pleas ehelp me to understand in more details the effect of Co BCCH-TCH????
This problem come from the frequency planning strategy .
no dedicated band for BCCH and TCH separately so it makes high interference on both side especially from BCCH because they are not using DTX and Power control so all time TCH frequency with the same BCCH frequency is interfered and make high call drop and SDCCH drop,TCH congestion, Handover failure and so on.
BR
RF

[justdream]

Thanks, but I would like to clarify that I'm speaking about Co BCCH-TCH neighbours which menas

two sites shooting to each ohters and defined as neighbours while one of them use BCCH 'x1' and the facing one use TCH also 'x1'

[ghassen]

Thanks, but I would like to clarify that I'm speaking about Co BCCH-TCH neighbours which menas

two sites shooting to each ohters and defined as neighbours while one of them use BCCH 'x1' and the facing one use TCH also 'x1'

i think that this frequency planning problem two sites with same frequency one for bcch and the other with tch and they have same bsic but power is too much that the bts or msn cannot distinguish between tch and bcch this from my point of you i don't know if other share the same idea because i've never seen something like that

[justdream]

No, I didn't say that they have the same BSIC,
they are two neighbour sites, one use the same BCCH 'x1' the ohter use 'x1' as TCH

[ghassen]

No, I didn't say that they have the same BSIC

did you mean that BCCH and TCH frequencies are overlaping ???
are these two channel on the same trx and same site or comming from diferent sites? plz answer me

[justdream]

That's what I mean...and sorry if I wasn't clear

[ghassen]

That's what I mean...and sorry if I wasn't clear

try to find out something about power control sincerely I've never seen something like that

[justdream]

try to find out something about power control sincerely I've never seen something like that

Please tell me exactly: what do you want regarding power control?

[ghassen]

Please tell me exactly: what do you want regarding power control?

one site with bcch at the frequency number 48 and the other site with tch on 48 but the power of the tch is too high and then it comes that the tch is overlaping with bcch ms cannot destinguish between both

[justdream]

very good, my man........
That's what I search about

[apo7]

If the TCH is overlapping with the BCCH most probably, the BSIC will not be decoded and the MS cannot distinguish between the sites or there will be handover failure.

[ghassen]

If the TCH is overlapping with the BCCH most probably, the BSIC will not be decoded and the MS cannot distinguish between the sites or there will be handover failure.

if the bsic is not decoded and we have co bcch-tch then the system will distinguish between the too cells with their timing advance and the nearest one will be chosen causing problem to the guy using the tch

[hassen]

Hi
If you complies with the conditions of Multiple Reuse Patterns there is no problem.
and of course as you know :time slot 0 is used for BCCH and for the same frequency
time slot 1,2....7 are used for Tch.but The problem that we can meet ,when 2 sites are not really synchronized.
if your BTS are synchronized using GPS your are lucky
if no avoid .
Br Hassen

[venom]

Frineds,
can you tell me from your experience, what's the effect of having Co BCCH-TCH?
as all people here just care about Co BCCH-BCCH and Co TCH-TCH...

so pleas ehelp me to understand in more details the effect of Co BCCH-TCH????

Brother, you can not define Co-BCCH and TCH in database for SIEMENS. I am sure this is an internal check for other vendors as well. Obviously the Database will give you an error of "Already defined frequency" if you try to re-define it in your TCH/MAL list. The logic behind is that BCCH is defined on a seperate TRX where as the hopping trx of the similar cell will give you an error if the frequency is assigned on any other TRXs (whether it is bcch or fixed or baseband, which means you can not use it in a synthesized hopping).

Now if i change your question in a way like there is a three sector site and every cell is having a different MAL List, for example

Cell A : 78,79,80,81,82,83,84,85,86
Cell B : 63,64,65,66,67,68,69,70,71
Cell C : 72,73,74,75,76,77,78,79,80

and now you have assigned the BCCH like

Cell A: 63 (because it is not used in its MAL List, the system will accept it)
Cell B: 73 (similar case)
Cell C: 70 (similar case).

In such scenario the system will accept the frequencies but the co and adjacent effect will remain on the BCCH all the time without considering the effect of the neighboring sites. By doing this we are creating the internal interference on the BCCH and it will give you a bad DL quality and also the Drop Call rate would be high. I hope it helps

[ghassen]

Brother, you can not define Co-BCCH and TCH in database for SIEMENS. I am sure this is an internal check for other vendors as well. Obviously the Database will give you an error of "Already defined frequency" if you try to re-define it in your TCH/MAL list. The logic behind is that BCCH is defined on a seperate TRX where as the hopping trx of the similar cell will give you an error if the frequency is assigned on any other TRXs (whether it is bcch or fixed or baseband, which means you can not use it in a synthesized hopping). I hope it helps !

yes this true you cannot even define a same arfcn in the neighbour cell with siemens

[venom]

yes this true you cannot even define a same arfcn in the neighbour cell with siemens

In SIEMENS you have some idiot checks as well, you also can not define the Co-BCCH Neighbors with different BSICs. Which is really stupid !!

In my previous example, just ignore the fact of Neighbors because i just gave the answer to ur query which effect of Co BCCH and TCH of same Cell.

Thanks

[ghassen]

In SIEMENS you have some idiot checks as well, you also can not define the Co-BCCH Neighbors with different BSICs. Which is really stupid !!

In my previous example, just ignore the fact of Neighbors because i just gave the answer to ur query which effect of Co BCCH and TCH of same Cell.

Thanks

can you explain why you try to do this co bcch?

[venom]

can you explain why you try to do this co bcch?

Sure brother, In SIEMENS we have some stupid and good healthy checks. The sites are always planned in phases, so obviously the number of sites increases with the period of time (phases). Nowadays, the optimization and planning both are different departments so suppose a new site came to a heavily urban area where the optimization engineer have not audited the neighbors and frequency planning engineer tried to reuse the frequency but due to the OLD-created neighbor the frequency does not get set. This obviously creates frustration because the concept of planning is not to look for the neighboring frequencies but to assume the frequencies that will hit your serving cell. For that Drive Test, Scan drive is very important. In many cases when you try to do automatic frequency planning the output plan is not good if your neighbors are not audited. The system always assumes that if you have created the neighbor then the site is withing the range, whereas it is not always the case !

In simple words, co-bcch neighbors check is good but sometimes it also creates difficulties. If you take my opinion then system should accept the values of Co-BCCH if the bsics are different. The check is good if you are assigning Co-BCCH and Co-BSIC. Obviously the planner or AFP tools are not stupid enough to give the logical co-bcch neighbors !!

[khoibt]

Frineds,
can you tell me from your experience, what's the effect of having Co BCCH-TCH?
as all people here just care about Co BCCH-BCCH and Co TCH-TCH...

so pleas ehelp me to understand in more details the effect of Co BCCH-TCH????

CO-BCCH mean BCCH and TCH used a frequence, co TCH-TCH is too.
sorry, my enlisgh is bad!

[mp9413]

No, I didn't say that they have the same BSIC,
they are two neighbour sites, one use the same BCCH 'x1' the ohter use 'x1' as TCH


Hi justdream,

If you have plenty of spectrum, just avoid co BCCH-TCH.

It's not easy to give a general description. Depends on the number of TRX of the cells, the performance will be different.

You should find that the handover success rate between the pair is lower than normal figures.

If the handover count is small, it means the coverage overlapping is relative small and Co-BCCH TCH is possble. Otherwise, the overlapping region should have quality issue.

Besides, the Co-TCH cell may also cause false measurment for the CO-BCCH Cell in MS close to the cells and hence false handover may occur.

Hope I make myself clear.

[bushdary]

the bsci is on the tch