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SDCCH Mean Holding Time

pix - 10th January 2008  (10:59 GMT)

i don't know the MSC, sorry... not my field at all :)

Promod - 10th January 2008  (10:41 GMT)

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.


rala - 10th January 2008  (04:14 GMT)

Thank you Pix, I got it. ;)

Pix - 9th January 2008  (16:33 GMT)

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 !!


pix - 9th January 2008  (16:29 GMT)

2nd part of the post :
typical duration of sdcch :

LU is short
TC is short

OC is long
SMS is long


pix - 9th January 2008  (16:27 GMT)


This is not SDCCH DURATION !!

SDCCH duration starts at IMMEDIATE ASGNMENT COMMAND and finishes when the SDCCH is released (switch to TCH, end of location update request, end of SMS, drop, etc...)

Water - 9th January 2008  (14:39 GMT)

Hi guys, please help me.
some three weeks ago, we started experiencing an increase in sdcch traffic, meanholding time, sdcch drop,sdcch congestion in almost every cell in our network.
I checked whether sms trends have changed some how, but there hasn't been any changes.
What could be the cause of such an increase in sdcch measurements.


rala - 9th January 2008  (07:21 GMT)

Dear Pix,
In your point of view,
if the LU requires SDCCH = 3 s.,
how about the call set up?

I try to find out these time from TEMS, the time from "Immediate Assignment request" to "Immediate Assignment complete" of call set up and LU is about 2 s..


Pix - 9th January 2008  (05:55 GMT)

yes, it's shorter. as i said, it's about 3 seconds...

rala - 9th January 2008  (04:38 GMT)

One more thing that I see after split the LAC is the Location update in the cell that have the SDCCH MHT decreased is very high.

How long time the location update use the SDCCH channel when compare to the others(MOC, MTC)? Is it shorter?
(If it is shorter it might be the cause of the SDCCH MHT decreasing.)


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