CRH parameter issue

Hello Samer,

What kind of effect are you looking for ?

You should see a decrease of the number of 2G LAU on cells located at lac borders.
However, it might be difficult to see it… because there is still many 2G LAU due to 3G to 2G mobility (at the end of a call with IRAT HO , or Idle mode 3G-2G). So you shouldn’t expect such a huge impact of CRH on the number of 2G LAU. On top of that, CRH will reduce the pingpong 2G LAU, but many MS are really moving from LAC to LAC (physical mobility along highways, roads, rails…), in which case the CRH will only delay the inevitable LAU.

To reduce the 3G2G mobility,
– activate the “fast reselection”,
– inhibit the IRAT HO,
– decrease the qRxlevmin (from -112dBm to -114dBm for example)

Cheers,

pix

hi samer,

ok, so in this case I believe, if I remember correctly, that you need to activate the computation of the C2 criterion.
This is controlled by a radio parameter in ALU. But I need to check it out in E///. I’ll answer more precisely tomorrow.

br /pix

hi,

No, nothing special in E///. CRH and CRO are always active.

BTZ – Ensure that CRH is set to a high value in the neighbours of the cell you are observing.
If CRH(neighbours) is high, that will reduce the number of incoming cell reselections in the serving cell.

I can have a look at your settings if you want ? Please list the parameters values :
CRO
TO
CRH
PT
T3212
ACCMIN
CBQ

br / pix

ok… but exactly, what are you looking at ? can you share some values ?

with a CRH = 14, you should see a huge issue in GPRS mobility (a lot of TBF drops)

you should also see less SDCCH LAU, and a decrease in CSSR, because MS are stuck in their serving cells, without being able to move to (reselect) a better neighbour cell.

With a ACCMIN = 110, the effect should be even more pronounced.

The Ericsson implementation of the CRH is fine, I can see it in the many DT I’ve done, no worry about that aspect.

Let’s do some testings ? select two cells, one from each side of a LAC border.
Put CRH = 0dB on both cells
Put CRO = 10dB on cell A, observe that trafic increases in Cell A
Put CRH = 20dB on cell B, observe that trafic increases (a little) on cell B, and decreases (a little) on cell A. Also, you should not there is less SDCCH LAU in cell A.

Now there is another possibility that the border between cell A and B is very “poor”, meaning that RXLEV dips below -110dBm, in which case the MS will not be using the CRH anymore.
CRH works well if RXLEV at borders are “CRH” dB higher than ACCMIN.

Let me know how it goes…