SDCCH dimensioning for HR environment

Hi!
We have Alcatel BTS use Sattelite Abis. please tell me:
Do we need use GPS to synchronise or not?
Now we set Free running, I don’t know about stabilisation.
Thank

Hi after implementin AMR half rate in our network TCH and SD completion rates has gone very bad in our network for sites carrying more than 30% of AMR half rate traffic.

Also if i enable the FACCH call setup parameter in BSC ,will it reduce the SD congestion .And also if we make trx signalling for such sites to 48kbps.Is going to help us

hi balenseng,

frequency hopping and a slow call setup/cell reselection are probably not related. On which indicators are you basing this study ?

Is it statistical or only drive-tests results ?

Balanseng,

I would recommend you also have a look to QoS statistics, to confirm that there is actually a difference between “before hopping activation” and “after hopping activation”. you might get a clearer picture of what is really going on, and whether the issue occured right at the time of the hopping activation or not.

however, if you’re sure of yourself, you must contact your vendor (which brand is it ?), so they can check the frequency hopping is working well in your release.

frankly, unless there is an issue in your network software, because i can’t see how frequeny hopping can relate to call setup and handover delays… but i don’t know… i simply never experienced that or heard about it, and i can’t even imagine what could be the problem.

good luck ! and tell us which vendor is it…

hello ravi,

i think you’re referring to a possible issue when using the power control and you’re locating very close to the BTS. The power attenuation beween different TRX and even different timeslots of the same TRX can be up to 30dB…

Normally, it should work fine, but if you’re having a doubt, why not simply deactivate the downlink power control ?

I use a GSM 900 Ericsson systems, but suddenly there are slow handovers and high cell re-selection. Dynamic MS and BTS Power control are both activated.
This causes inteference problems as a mobile take long while camping on a worst cell.

hello tranhung,

what is the cause of HO failure G900 to G1800 ?

if it is congestion, then i would say it is normal. the preferred band HO will push MS from G900 to G1800, leading to HO failure due to congestion. It is a normal behaviour, a “wanted” behaviour (preferred band HO will push the MS…)

if it is “radio failures”, then i would check your HO tresholds, especially the l_rxlev_cpt_ho and the traffic condition (any load ?) to perform the “preferred band ho”.