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you should check your BSC’s
(all the cells of the network, or just one or few BSC’s ?)
if ALL the network, then it might be the MSC. Either a MSC board, or a timer that has been modified. The SDCCH is used for exchanging messages between MS and MSC. If it takes longer for the MSC to answer these messages, it might impact the whole network.You could investigate the VLR as well. The VLR is taking part during the authentication. If the VLR is slower, it will increazse the length of the SDCCH, etc.
That’s a very interesting problem, please let me know how it ends !!
Thanks,
pixThank you Pix, I got it. 😉
Hi Pix,
I would like to know,
1.Max MSC Capacity
2.How it is calculated to the from Transcoder capacity to till MSC end.Regards,
Promodi don’t know the MSC, sorry… not my field at all 🙂
Hi Pix!
The sdcch problem has affected most cells, in different BSCs, and different MSCs!
If you talk of the VLR then i will try ask the core engineers to check that for me!
I have been suspecting the LAPD signalling, but now i wonder what could have triggered such a problem in so many cells in different BSCs!Thanks for the other response!
Thanks Guys!
Hi Pix,
Some cells which are facing towards railway line are having high call drops and SDCCH drops.So will you suggest me what could be the reason?
Regards,
Promodto Water
There are some things, that may cause sdcch traffic increasing:
– enabling Check Imei feature in MSC/VLR or increasing it’s frequency per radio event (for example, performing this procedure not only in Location Update cases, but in MOC, MTC, etc. and/or more frequently).
– enabling TMSI reallocation feature in MSC/VLR or increasing it’s frequency per radio event in (see example above)
– enabling authentication feature in MSC/VLR or increasing it’s frequency per radio event (see example above)Promod,
do you suspect the cell is catching railway traffic ? if yes :
– do you want this cell to catch the fast moving traffic ?
–YES : reduce the HO MARGIN, the DL EMERGENCY LEVEL THRESHOLD, disable DL power control, and strongly reuce the averaging windows (to 2, for instance). Drawback : you will impact the slow moving traffic in this cell as well.
— NO : harden the incoming HO from the cells covering the fast moving traffic (higher HO MARGIN(n,s)) and direct this traffic from one “railway” cell to another “railway” cell. You can do this with LINK FACTOR and HO MARGIN (adjacency parameters)
Hi Pix,
1.My Power margin handover is 6db,Level margin handover is 6db and quality margin handover is 0 db.As i guess that is we can change Power margin to 3db so that fast moving mobiles will get immediately handovers
and what is the link factor parameter? In nokia what is the parameter name?Please suggest me which will be the better way?
Regards,
Promodthe power margin is an adjacency parameter, isn’t it ?
in this case you could set :
power margin (railway cell, standard cell) = 12db
power margin (railway cell, railway cell) = 3db
power margin (standard cell, railway cell) = 12dbThat will certainly help. You see the idea behind these values ? Maybe you can use other parameters to achieve the same effects, as I’m not sure what are the nokia’s HO ALGORITHMS.
Regards,
Pix
I don’t know the nokia parameters, sorry.CAN someone brief me what is Mean holding time?
Dears From some weeks ago we faced with SDCCH MHT incremnet while radio team check and confirm that SDCCH traffic is decreased , there wasn’t any change on core side.
would you pleas help me what could be the reason ?
Hello,
If the SDCCH MHT has increased, then the SDCCH traffic must have increased as well !
Traffic = MHT * SDCCH_AttemptsSo unless the overall number of SDCCH_Attempts have decreased, it doesn’t make sense to me.
If attempts have decreased, then something must have occurred ! (for example : less IRAT HO 4G-2G or 3G-2G, or fast reselection to UTRAN/LTE)
You may consider checking the cause of SDCCH establishments (MOC, MTC, LAU, SMS, IRAT reselection, etc) thanks to RAN counters. This may point you to the right direction.
BR / Pix
MHT Mean Holding Time is the average amount of time in seconds on KPI usually that the call was connected before the UE hung up the call, you’d be surprised how short the Mean time is when you see high traffic cells, I see 50 seconds 20 seconds, most people these days call people up and say, ‘hi, be there in 5 minutes’ and hang up so this is why it’s so low these days, but if it’s usually 50 seconds and drops to 10 seconds then you may have a silent call issue or poor call quality issues
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