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Reply To: HO failure cause congestion

#61343
pix
Guest

and do you see congestion on the 3 sectors ?

– from which cell are those HO coming from ? (that’s for you, I don’t need this answer 🙂 )

– could you check the indicator
RTCH_allocated_peak (GTCTRCAMN) per hour, and see if the max number of TCH TS are used ?

what we could try to do is share the incoming HO among the 3 sectors. We can do that by ensuring the 3 sectors are defined as neighbours with the serving cell.

Do that first, if it wasn’t done… And wait.

If it doesn’t work then it becomes complicated because the load evaluation is done every 5s. But let’s try :

In the serving cell and in the 3 neighbours:
CELL_EV = GRADE
EN_LOAD_ORDER = ENABLE
LINKfactor(0,n) = 0

And in the 3 neighbours
—————-
Load_Factor_1 = -10
Load_Factor_2 = -14
Load_Factor_3 = -16
Load_Factor_4 = -18
Load_Factor_5 = -20
—————-
Loadlevel_1 = 40%
Loadlevel_2 = 50%
Loadlevel_3 = 60%
Loadlevel_4 = 70%

By doing this, the BSC will quickly consider the “best” neighbour as loaded. The 2 further neighbours will gradually become more attractive.
It will work only if all inc HO are not coming exactly at the same time.

To avoid the second neighbour to send the traffic to the 1st neighbour (as a kind of ping pong situation), you should activate the Traffic HO between the 3 sectors :
with “i” and “k” from 1 to 3
EN_TRAFFIC_HO(ni, nk) = Enable
DELTA DEC HO MARGIN(ni) = 20dB
DELTA INC HO MARGIN(ni) = 20dB
HIGH_TRAFFIC_LOAD(ni) = 70%
A_TRAFFIC_LOAD(ni) = 1 (5s)
N_TRAFFIC_LOAD(ni) = 1 (5s)

Those settings are a test. They might generate unexpected behaviour… Be ready to rollback to default values.

This is a little weird, perhaps dangerous, but it will work IF you are in a rural area with almost no “static” traffic.

For the UL LEV and UL QUAL HO, you might also check the PATH BALANCE and the RMS of the serving cell.
Are there interference ? Or a bad coverage ?

cheers