Mismatch lac in MSC/BSC question

**Mr_Piongly** · 2011-12-21, 04:59 AM

Hi

I know that in BSC we define for each cells the lac ( or more precisely the cgi)

but that info is also specified in the MSC ?

The corresponding MSC of a BSC has to know the lac of its cells?

What happens if there is a mismatch about lac between msc/bsc ?

thx for your attention

**Finetopix** · 2011-12-21 04:59 AM

**rfoptman** · 2011-12-21, 05:03 AM

This mismatching will cause the Call setup failure, while handover still will be done!

**sabila** · 2011-12-21, 07:33 AM

call setup ail
offcourse handover failed to i think my bro.
because if cannot call what will "handover" to other cell/site

**rfoptman** · 2011-12-21, 11:53 AM

If call started in a Cell A (without mismatching LAC in BSC/MSC) successfully and then handover intra MSC to Cell B (With mismatching LAC in BSC/MSC), then the call will be continued still.

**mkmittal21** · 2011-12-21, 08:10 PM

You can not be able to call setup.

**Mr_Piongly** · 2011-12-22, 03:32 AM

Please,
could you explain the reasons why we have call setup failure?
thx a lot

**louvre** · 2011-12-22, 03:45 AM

Hi,

its basics of GSm, During the call setup many protocol negotiation are done with MSC one of the key way of identification of a cell in network is cell id but as per spec it doesn't need to be unique in which case vendor use LAC-CI for identification as, as per specs CI has to be unique in a LAC, which is part of CGI which is again unique in the network. so if the CGI in the BSC doesn't match with CGI in the MSC then MSC doesn't recognize the BSC cell during call setup as MSC doesn't find any reference of the CGI presented by the BSC, but during HO CGI is not involved and within a MSC, HO never use MSC as BSC is sufficient to negotiate the HO. Hope this clear your doubt. for further reference please look at the call setup flow you will come to know what protocol messages are exchanged between MSC and BSC during setup. Also a key point if you switch off and switch on a mobile it can be possible the mobile will show network coverage.. so its imperative that this definition is correct and always allinged.