Low paging success rate – Low e2e-CSSR

It happened since the installation or it started after your changes?

Maybe is a fraud case. Someone is using your card for VoIP. check the MS IMSI/IMEI if it is the same in every failure ban him.

I note your BSC is ALU and your MSC is Ericsson, therefore I deduce there ‘maybe’ an issue with inconsistent parameter settings.
Typically in an Ericsson network, the T3212 parameter should be set relative to MSC parameter BTDM (Base Time Duration), which results in detach.
BTDM is the time supervision for implicit detach and it is crucial for BTDM to be higher than T3212 (i.e. BTDM ≥ T3212) so that the MS is not detach from the network before the period registration kicks in.
If BTDM is less than T3212 (BTDM < T3212), this will result in the MS getting detached earlier than MS doing periodic location update. The typical default values I have seen for T3212 is 30 or 40 (3 – 4 hours), with 40 being the normal default. In Ericsson the units of T3212 and BTDM (for Ericsson MSC) are different as well, i.e. T3212 uses deci-hour and BTDB uses minutes. I am unsure what the settings are in your ALU BSC, however please ensure your T3212 timer in ALU BSC is less than or equal to the BTDM in your Ericsson MSC.

hi

yes, the timers are fine. I’m not familiar with the guard timer (GTDM) though.
It seems quite radical to have T3212 = BTDM. I would allow few more minutes for the BTDM. But anyway, that’s not the problem here.

so let’s focus somewhere else.
perhaps it is due to bad coverage in some areas.. or unstable BTS that provides coverage only once in a while.
before the T3212 expires, the MS is actually ALREADY out of coverage and cannot be reached. During this time, the MSC still has the Ms attached, but physically the Ms is not reachable.
however your timers are already quite short (108mn), which is 3 times less than standard duration. The benefit is that such “unreachable” situation might last ( in the worst case ) 107mn max.

in order to verify this hypothesis, you could try to decrease T3212 and BTDM. If you see an improvement, then… good.

also, do what Smart asked : trace the IMSIs which are unanswered. If they are always the same, then… that gives some pointers.

regards
pix

Configuration of Assocaited HLR on the MSC
Scenrio: having 3 HLR in Pool and .
an associated, to be seeing the HLRs as one on the MSC.

I have configured the M3UA link for the main HLR, am aslo using the links for the 3 HLR as the link for communication to the associated HLR, SCCPGT is configured and the SSN status is allowed

On the VLR request i can find the information of the sub on the MSC. What do u think is the problem?

Ayat,

– what about paging discard on LAPD link? (is your paging load per LAC>80%? if yes you may need to split concerned LACs or add a secondary broadcast channel on heavy cells)
– what is the value of your immediate assignement success rate per LAC as it also happen to reduce PSR? (congestion on signalling channel,…)
– check on the BCCH frequency plan and make sure interferences are minimised.