- This topic has 15 replies, 1 voice, and was last updated 14 years, 7 months ago by ami.
3rd December 2007 at 06:34 #49919amiGuest
pls any one can give me some solution of my problem?
I am working on Nokia BTS,facing a problem of HO failur beetwen inter BSC.BSC1 is in nokia BSC and BSC2 has been swapped from seimence to nokia,now all HO attempt from some sites of BSC1 are failling with only 5 sites of BCS2,whereas opposite direction HO is succesful.I can checked NCC,BCC,freq,CI and BSC in both BSC it is ok. I am not getting where is the problem.
pls help.3rd December 2007 at 11:55 #49920pixGuest
the problem might be in the NSS : check the definition of the BSC’s and the LAC’s are well done in the MSC.
I’m not expert in NSS, but i noticed that most of these HO interBSC problems are due to wronf settings in NSS.
Pix3rd December 2007 at 18:44 #49921AbdelGuest
This is an inter BSC handover, This kind of handover is controlled by the MSC you have to check your parameters or configuration at the MSC side.
Abdel4th December 2007 at 09:04 #49922amiGuest
hi pix & abdel,
thanks a lot for give your sugestion quickly.
I will check as you suggest,but I thik if there is a problem from MSC end or wrong BSC definition then all handover will fail between inter BSC.
in my case only 5 to 6 site of BSC2 are creating 100% handover fail.
so pls suggest if there is any other problem.4th December 2007 at 20:27 #49923pixGuest
how many cells are having interBSC HO between these two BSC’s ? More than 6, or only 6 ? It’s not very clear.
However, you can have a misconfig only for a certain LAC, or only for certain cells.8th December 2007 at 07:13 #49924amiGuest
there are 23 cell having inter bsc HO b/w these two bsc,and only with 6 cells HO failure is 100%.8th December 2007 at 23:18 #49925pixGuest
ok, you need to investigate further.
1. drive test : are there HO COMMAND sent to the MS when going from BSC1 to BSC2 ?
2. QoS counters or Abis+A interface traces (on both BSC’s) : can you plot the inter-BSC message flow and point out which message is “failing” ?
For instance : does the BSC1 send a HO REQUIRED to the MSC ? Does the MSC sends a HO REQUEST to BSC 2 ?
If you find which message i missing, then you know which equipment is not doing its job properly. Then you know where to check the configuration 🙂
interBSC message flow (p.37) :
http://www.swen.uwaterloo.ca/~knaik/750/gsm+dca.pdf11th December 2007 at 02:59 #49926AbdelGuest
Do you have a test mobile like the Sagem OT260? I think it has the capability of forced handover.If you can find it try the following:
1)Prepare SS7 signalling(BSSAP and MAP) at both the BSCs and the MSC.
2)Go to one of the cells with the 100% HO failure.
3)Try to make a call and then apply the forced handover to one of the cells on the other BSC.
4) If the handover is unsuccessful then go back and see your traces, then you may see the error. If you are unfamiliar with the ss7 messages MAP and BSSAP messages, you can make a handover in a normal cell then record the messages in line. Compare the messages of the faulty cells with the normal and see the difference. Some GSM vendors they decode the messages and it is very easy to understand but I don’t know about Nokia because I don’t have experience on it.
Abdel11th December 2007 at 13:27 #49927pixGuest
Air & A interface are 3GPP standards, only the Abis is not 100% standard.15th December 2007 at 16:03 #49928TNSGuest
Did you resolve your problem?
If yes, what was the problem in fact?
If no – ask someone to check the DPC definition of the cells ( from the swapped BSC ) in the NSS data base.
Wrong DPC for the target cell means 100% unsuccess rate when you try to perform an external BSC HO.
TNS15th December 2007 at 22:30 #49929pixGuest
what’s DPC ?18th December 2007 at 12:19 #49930FroodGuest
DPC= Destination Point Code18th December 2007 at 15:18 #49931pixGuest
thanks frood8th January 2008 at 07:32 #49932amiGuest
hi all thanks for your advice,I have check DCP(actually DCP is in siemens system in nokia it is SCP-signaling code point).it is ok,now we have rehome that site into BSC1 and the problem of 100%failure is solved,but there is still aprox. 50% failure.8th January 2008 at 21:33 #49933AbdelGuest
Did you checked whether you have configured external cells for the adjacent cells of the two BSCs? If not then you have to configure these external cells at both the Nokia and Siemens BSC.