HSDPA RAB FAIL and PS Call drop

[khaledkhoudi]

Dear experts,

Can you help me in this problem: the vendor is Huawei

At the busy hour, some cells have the rate VS.HSDPA.RAB.SuccEstab.Rate smaller than 40%. also the PS rab fail is increased in these cells due to VS.RAB.FailEstabPS.Unsp which also power congestion. I tried to increase the ENU (Equivalent user number) to 200 but the problem persist.

I want to add that these cells also have a high PS call drop (more than 10%), so please i need your help urgently.

We're using the BSC version V900R012.

N.B: the DCCC is implemented and also we have problem in synchronization there is no IP clock.

Best regards,

[zeezzoo]

Dear Khaled ,

The counter "VS.RAB.FailEstabPS.Unsp" is also count for the resource congestion .

This is from hedex :

The failure cause is "Requested Traffic Class not Available","Requested Maximum Bit Rate not Available","Requested Maximum Bit Rate for DL not Available","Requested Maximum Bit Rate for UL not Available","Requested Guaranteed Bit Rate not Available","Requested Guaranteed Bit Rate for DL not Available","Requested Guaranteed Bit Rate for UL not Available","Requested Transfer Delay not Achievable" or "No Resource Available".

So the rab failure you have is caused mostly by power congestion .

please check the congestion counters again and let me know what is the main reason for the congestion .

67193613	VS.RAB.FailEstabPS.ULPower.Cong	Number of Failed PS RAB Establishments for Cell (UL Power Congestion)
67192612	VS.RAB.FailEstabPS.DLIUBBand.Cong	Number of Failed PS RAB Establishments for Cell (DL Iub Bandwidth Congestion)
67192613	VS.RAB.FailEstabPS.ULIUBBand.Cong	Number of Failed PS RAB Establishments for Cell (UL Iub Bandwidth Congestion)
67190408	VS.RAB.FailEstabPS.ULCE.Cong	Number of Failed PS RAB Establishments for Cell (UL CE Congestion)
67190409	VS.RAB.FailEstabPS.DLCE.Cong	Number of Failed PS RAB Establishments for Cell (DL CE Congestion)
67179967	VS.RAB.FailEstabPS.Code.Cong	Number of Failed PS RAB Establishments for Cell (Code Congestion)
67193614	VS.RAB.FailEstabPS.DLPower.Cong	Number of Failed PS RAB Establishments for Cell (DL Power Congestion)

[khaledkhoudi]

Dear Zeezoo

The main congestion is comming from the UL power congestion. i already try to change the ENU (Equivalent Number of Users) to 200 but the problem persist.
There is also HS user congestion in all these cells.

Waiting for your feedback.

[jayk]

Dear Zeezoo

The main congestion is comming from the UL power congestion. i already try to change the ENU (Equivalent Number of Users) to 200 but the problem persist.
There is also HS user congestion in all these cells.

Waiting for your feedback.

You Can Disable UL_UU_OLC in problematic cells. This switch will disable UL Power Congestion triggering. It helps.. but keep monitoring your RTWP

[pavi4u]

You Can Disable UL_UU_LDR in problematic cells. It helps.. but keep monitoring your RTWP

can u explain this parameter pls?

[khaledkhoudi]

Dear Jayk,

This parameter is already desactivated and i did not enable it in the first place.

UL_UU_OLC: UL UU overload congestion control algorithm. When the cell is overloaded in UL, this algorithm reduces the cell load in UL by quick TF restriction or UE release.

Waiting your feedback.

[agenov]

Increasing ENU is approach you can use till particular stage in order to avoid UL congestion. Change to the max possible simply means that you allow more and more users i.e incrase more and more the congestion also at the same time compromise RTWP and UL direction, i wouldn't say this is the best thing in this case. What you need to do is to offload the cell ( perform traffic balancing between neighbours) by introducing another carrier, antenna design change (tilt,azimuth etc), change of Idle/Diedicated parameters for reselection/handover or use different load control algorithms that Huawei provided.

BR
alex

[jayk]

Dear Jayk,

This parameter is already desactivated and i did not enable it in the first place.

UL_UU_OLC: UL UU overload congestion control algorithm. When the cell is overloaded in UL, this algorithm reduces the cell load in UL by quick TF restriction or UE release.

Waiting your feedback.

NBMUlCacAlgoSelSwitch should be Algorithm 2 , then Increasing ENU and UL_UU_OLC can help. If UL_UU_OLC is disabled, there will be no more power UL power congestion in cells.

[duman]

I need summ of "number of Failed PS RAB Establishments for Cell" if u know or u have counter could u pls provide.

[duman]

Hi,
Could u pls provide me formula which u calculated VS.HSDPA.RAB.SuccEstab.Rate.