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Reply To: HO failure cause congestion

#61337
pix
Guest

too many questions….

-SLIM-

in case of intra-BSC HO, the T7 method is not used. Sorry for my error. The target cells are tested one by one immediately by the BSC, as soon as HO is detected. In the nextr SACCH period if HO is still detected, the BSC will again try all candidate cells, until one of them is *not* congested.

now, for inter-BSC HO, during T7, if the best cell has changed before T7 expiry, the new candidate cell is sent to the MSC (new message “HO REQUIRED”). It is then up to the MSC to forward the HO REQ to the target BSC, etc. The new cell should supersede the old cell.

– SERGIO / BHT / LILY –
It is a common mistake : DO NOT USE HO Congestion in the TCH Congestion formula. It makes it artificially High. You should rather use the TCH “Normal Assignment” Congestion (TCNACGR), which is the proper way to monitor the congestion.
HO Congestion does not represent the reality, because BSC will attempt the HO so many times automatically !

But reducing the number of HO by increazsing the avg window is a great idea. The less the number of HO, the better.
A_PBGT_HO = 16
A_LEV_HO = 8
etc.

– LILY –

You misread the documents. The GRADE evaluation is WAY WAY WAY WAY better than the Order Evaluation.

In the serving cell :

CELL_EV = GRADE
EN_LOAD_ORDER = ENABLE
LINKfactor(0,n) = 0 (unless you want to give a static penalty or bonus to cell(n) )

And the load protection is done with those :
—————-
Load_Factor_1 = -2
Load_Factor_2 = -6
Load_Factor_3 = -9
Load_Factor_4 = -12
Load_Factor_5 = -15
—————-
Loadlevel_1 = 50%
Loadlevel_2 = 60%
Loadlevel_3 = 70%
Loadlevel_4 = 90%
—————-

I’m sure you understand how they work and how to tune them… The values I gave are tuneable, of course !

Why not “ORDER” ? Because you must tune each setting depending on the number of free TS left in the cell. Different cells with different number of TRX –> Different settings. Very tiresome to followup. Here, the Grade is using the “TCH Load”. It is smarter, nicer, cleaner, easier to follow-up.

Cheers
pix