Frequency problem on BCCH or TCH

[electron]

Hi Friends,



What is your tricks to find frequency problem in BCCH or Hopping in a cell(for example it is affected drops)

For example DL bad quality reason in TCH drops will suspects us there is frequency problem so it does not mean 100% problem is on BCCH maybe ther eis interference due to hopping TCHs !!


So how we can identify what exactly is the problem ?

For SDCCH also we can consider...


Thanks

[tsiz]

Hi Friends,



What is your tricks to find frequency problem in BCCH or Hopping in a cell(for example it is affected drops)

For example DL bad quality reason in TCH drops will suspects us there is frequency problem so it does not mean 100% problem is on BCCH maybe ther eis interference due to hopping TCHs !!


So how we can identify what exactly is the problem ?

For SDCCH also we can consider...


Thanks

I have identified issues where co-bcch and co bsic have affected performance. There were no degradations observed but the HO fails were 100%.

As far as co bcch only, I have definetly seen DL drops and also I check if it is causing ICM bands by running the RLCRP command. Also you can try moving the BCCH to a different radio to see if the drops follow.

As far as TCH, can you retune the site with a totally different frequency to see if the drops improve? This has worked for me in the past.

But not all DL quality may be related to frequency. Most of the times this is related to a bad radio. Also a wrong MAIO or different HSN will cause this problem although more of them would be sudden loss drops. You can block down the radio to see if the drops follow.

[RF engineer]

Hi Friends,



What is your tricks to find frequency problem in BCCH or Hopping in a cell(for example it is affected drops)

For example DL bad quality reason in TCH drops will suspects us there is frequency problem so it does not mean 100% problem is on BCCH maybe ther eis interference due to hopping TCHs !!


So how we can identify what exactly is the problem ?

For SDCCH also we can consider...


Thanks

Your hopping is BBH or SFH ,
if BBH you can easily find which one is the problem from drive test you can see C/I for each frequencies.
Or change HSN in cells to non zero you can see the decrement. And for SDCCH shifted to other TRX and see the performance.
BR
RF

[electron]

Thanks for the reply,



Actually in some cases i have seen DL Bad quality reason for TCH drop and i changed BCCH and HSN even in teh condition which there was not Co-BCCH in nearby . In this situation can we conclude there is bad quality on Hopping channels? (MAIO list was correct). Is there another way to identify at first in which CHGR we have bad quality DL ?

What will your recommendation and solution in this cases?



Thanks

[danikd]

Hi Friends,



What is your tricks to find frequency problem in BCCH or Hopping in a cell(for example it is affected drops)

For example DL bad quality reason in TCH drops will suspects us there is frequency problem so it does not mean 100% problem is on BCCH maybe ther eis interference due to hopping TCHs !!


So how we can identify what exactly is the problem ?

For SDCCH also we can consider...


Thanks

Based on your explanation I assume that the network infrastructure is E*******.

The SY hopping implementation in E******* done with two channel groups 1 for Non-hopping BCCH and 2 for hopping TCH.

Since drops are counted on cell level only you can not be sure where it happen.
The most efficient way to investigate channel group performance is MRR.
In MRR (Mobile Reports Recording) you can easily differentiate BCCH and TCH channel groups performance in terms of bad quality for DL and for UL.

In case of BB hopping (all TRXs BCCH and TCH are in the same channel group) MRR will not provide such resolution. In order to investigate BB hopping cell (avoiding intensive drive test), you have to switch off hopping, then change BCCH frequency to best possible frequency (other than current) and then analyse the performance.
Another way for BB hopping is to exclude BCCH from hopping by defining two separate channel groups and using MRR.

Hope this helpful

[tsiz]

Thanks for the reply,



Actually in some cases i have seen DL Bad quality reason for TCH drop and i changed BCCH and HSN even in teh condition which there was not Co-BCCH in nearby . In this situation can we conclude there is bad quality on Hopping channels? (MAIO list was correct). Is there another way to identify at first in which CHGR we have bad quality DL ?

What will your recommendation and solution in this cases?



Thanks

Yes..when you type RLCRP:Cell=xxxxx; this should give you the ICM bands with relation to the CHGR. You can then determine which CHGR is having bad quality.

[icebreaker05]

Based on your explanation I assume that the network infrastructure is E*******.

The SY hopping implementation in E******* done with two channel groups 1 for Non-hopping BCCH and 2 for hopping TCH.

Since drops are counted on cell level only you can not be sure where it happen.
The most efficient way to investigate channel group performance is MRR.
In MRR (Mobile Reports Recording) you can easily differentiate BCCH and TCH channel groups performance in terms of bad quality for DL and for UL.

In case of BB hopping (all TRXs BCCH and TCH are in the same channel group) MRR will not provide such resolution. In order to investigate BB hopping cell (avoiding intensive drive test), you have to switch off hopping, then change BCCH frequency to best possible frequency (other than current) and then analyse the performance.
Another way for BB hopping is to exclude BCCH from hopping by defining two separate channel groups and using MRR.

Hope this helpful


H electron,
This is a network-wise strategy..
If your using the SFH, try to check the network traffic trend vs the network TCH drop in statistics. In most cases, TCH drops increases as your netwrok load increases. If you are aware Fractional loading, you can at least have an overview of the collision in your TCH. Fractional loading determines the probability of collision. For example, I have 30 G900 channels, I have divided the BCCH-TCH into 12-17 and one guard band. Using 1x1 SFH on a 3 trx cell i will have fractional loading of 0.35 and for 4 TRX its 0.52. In order to achieved good quality you should maintain 0.45 or below. Now if you have deployed 444 network wise, you will see that your drops will increase with traffic. Try to reduce config or add more frequency in hopping channels. Remember in E///, we have BSC par called FBCHALLOC which we could to prioritize or hopping TCH rather than our BCCH TCH's. Retuning or changing HSN may not give full benefit network wise. You must consider downtilt first if you a tight frequency re-use. Check MRR frequently.

Hope this gives you a hint, actually we are having investigation on this on our network..


BR,
icebreaker

[electron]

Thanks to all friends for the complete answers.


Regards