SDCCH blocking is high

Hi Dirty,

T3212 = 4 hours (default)
every 4 hours, a mobile will send a location update message to its BSS, using a SDCCH subchannel for 3 seconds 🙂

increase T3212 : instead of every 4 hours, maybe do every 6 hours.
It reduces the amount of location updates in your network, reducing the SDCCH load (and TCU load as well)
drawback : there is a timer in the NSS that can expire. If the NSS receives a LU before the expiry, then the timer is restarted. Otherwise, the mobile becomes “IMSI DETACH”-ed. So ensure that your NSS timer is well defined.
There must be another drawback, but I can’t remember…

Decrease T3212 : instead of 4 hours, do 2 hours. That will double the amount of periodic LU in your network, overloading TCUs and SDCCHs.

Regards,

Hello Da Architect,

If you urge so badly, I’d rather tell you now then 🙂

…

Ok, i’ve been looking for the name of the parameter for 30 minutes now. And I just can’t find it ! NSS is so obscure, it is scary.

However the 3GPP doc confirms what I said earlier :

“2.4.2 Implicit IMSI detach
Implicit IMSI detach operation is the action taken by the VLR to mark an MS as detached when there has been no successful contact between the MS and the network for a time determined by the implicit detach timer. The value of the implicit detach timer is derived from the periodic location updating timer. During an established radio contact, the implicit detach timer shall be prevented from triggering implicit detach. At the release of the radio connection, the implicit detach timer shall be reset and restarted. Implicit IMSI detach shall also be performed in the case of a negative response to an IMEI check.”

(ref : Location registration procedures
(GSM 03.12 version 7.0.0 Release 1998)

I’m sorry, I really can’t find its name. But if you find it, PLEASE share it with me 🙂

Regards,

Plz tell me the reason for high sdcch blocking in showcase even if traffic is less?

I am having problems with our network on SDCCH. Two sites are having low SDCCH accessiblity and the company has a threshold of 97%.
please can you tell me what are the possible cause for this drop

Gerald can you post the formula you using

hi
plz tell me if utilization is high will it lead to SD blocking.some of my cells have utilization above 200% but no SD Blocking n few with 150% have SD blocking up to 25% even if SD available is same for both case.

The answer is in this post, keep looking. It’s a bit in the past.