- This topic has 4 replies, 1 voice, and was last updated 11 years, 11 months ago by Pix.
22nd May 2009 at 13:23 #57227ZGuest
Does anyone have a clue how a trend of an increase in EDGE traffic could cause an increase in Voice Drop Call Rate?
It can be seen in trend during a year, or in a day (drop call increases together with EDGE DL Mbytes in the afternoon, after 4 pm)…
I have suspected on MS GPRS Power Control, but agressive UL GPRS PC even made it worse…22nd May 2009 at 15:44 #57228JackyGuest
Have you checked the PDCH configuration in the network? and which BSS?22nd May 2009 at 17:17 #57229PixGuest
Are you sure the drop is corelated to the GPRS traffic ? What about CS Traffic ?
I would say that at the busy hour (CS and PS), then more radio frequencies are busy, therefore the quality of the air interface is degraded. That leads to higher call drop rate.
If that’s not the case, then let’s assume the GPRS traffic does indeed impact the CS drop. The only thing i can think about is how the capacity is distributed between CS and PS. Perhaps a CS call is trying to perform a HO towards a cell, but this cell can’t accept this incoming HO because all its resources are already occupied. And perhaps the PDCH are not released to make room for the incoming HO (this is a strategy which is vendor dependent).
In order to try out this method, try decreasing the max amount of pdch in the cells, and globally, try making the allocation of CS call more aggressive –> PDCH should be preempted faster.25th May 2009 at 06:14 #57230ZGuest
It’s Ericsson BSS. I’m sure it is corelated to GPRS traffic, since when we implement UMTS technology on the same site, UMTS takes data traffic away from GSM cells, voice traffic remains almost the same and drop call rate is improved… Voice PBH is usually at 11 am, and data traffic starts to grow after 6 pm, when voice traffic is low (but absolute number of drops is very similar to voice PBH number of drops)…25th May 2009 at 08:40 #57231PixGuest
What is the cause of drop?
During GPRS transfer, there is no DL Power control. So basically, the amount of interference increases in the network if there is too much PS Traffic.
UL Power Control is usually not activated neither, so same thing apply in UL as well.
Can you see an increase in the ratio of Quality HO, or Interference HO (especially downlink ?)
You said the GPRS UL PC made it worse. How can GPRS UL PC impact the CS Call drop ?!? GPRS PC and voice PC are different mechanisms, with different parameters.
You can check also something (this is vendor dependent): the PS traffic is perhaps enjoying the best TRXs of the cell (less interference, less hopping, … ?) while the CS traffic is set on the worst TRX ?