FACH Congestion

[gunpowder]

Dears,

How can i monitor FACH congestion in Huawei RAN 14 as i can't find any counter in M2000 related to this issue

Thanks

[giegala]

Hi,

from some old HW doc, the load of FACH should be calculated accordingly:

One SCCPCH:
FACH Utililization = VS.CRNCIubBytesFACH.Tx*8 / ((60*<SP>*168*1/0.01)* VS.PCH.Bandwidth.UsageRate*6/7 + (60*<SP>*360*1/0.01)*(1- VS.PCH.Bandwidth.UsageRate*6/7))
Two SCCPCHs:
FACH Utility Ratio = VS.CRNCIubBytesFACH.Tx*8 ((60*<SP>*360*1/0.01)*
Where:
<SP> is the performance statistics period and the unit is 1 minute.
VS.PCH.Bandwidth.UsageRate is a calculated value, which is equal to <VS.CRNCIubBytesPCH.Tx>/(<VS.CRNC.IUB.PCH.Bandwidth>)*<SP>*60.
Because VS.CRNCIubBytesPCH.Tx includes PICH（40bit）and PCH（240bit）are accumulated, PICH load has has to be substracted.

cheers!

[khurrambilal01]

Dears,

How can i monitor FACH congestion in Huawei RAN 14 as i can't find any counter in M2000 related to this issue

Thanks

There are different counters to monitor FACH Congestion.
Below are counters to see either the congestion on FACH is due to traffic DCCH or signaling CCCH.

VS.FACH.DTCH.CONG.TIME
VS.FACH.DCCH.CONG.TIME
VS.FACH.CCCH.CONG.TIME

If flow control is enabled on RNC level for RRC then you might face FACH congestion during peak time due to CPU usage or high users. Below counter:

VS.RRC.FC.Num.FACH.Cong

VS.CRNC.IUB.FACH.Bandwidth shows you the bandwidth which is configured for FACH.

[saurabh.chauhan123]

hi

how much value of "VS.FACH.DTCH.CONG.TIME" is considered as High fach congestion or is there any way to calcualate Fach congestion % ?

Please also share wayz to reduce fach congestion ,i mean reduce "VS.FACH.DTCH.CONG.TIME" .

[P.T.E.]

u can use second SCCPCH for FACH or Iub expansion or both of them

[vaampeere]

hi

how much value of "VS.FACH.DTCH.CONG.TIME" is considered as High fach congestion or is there any way to calcualate Fach congestion % ?

Please also share wayz to reduce fach congestion ,i mean reduce "VS.FACH.DTCH.CONG.TIME" .

Anything above 40s for FAH DTCH.CONG.TIME is congestion imo.

There are many way in algo switches which you can use to reduce FACH congestion.

You can use F2D or D2F timer value adjustment, or you can also allow F2P direct. Best way is to add one more SCCPCH where ever necessary.The above formula looks a bit complicated for calculating FACH utilisation.I remember seeing a straightforward one before, but it was for RAN 13.I understand what you mean for the counter name changes in RAN14.Its a drag!

[rumy]

What was the thing that came into ur attention when u started looking for FACH congestion? do u have HS over FACH enabled?

[khurrambilal01]

What was the thing that came into ur attention when u started looking for FACH congestion? do u have HS over FACH enabled?

When Fast Dormancy is enabled and you are experiencing FACH congestion then definitely your user is being affected, Normally if there is FACH Congestion, RRC success rate is affected too.

[rumy]

When Fast Dormancy is enabled and you are experiencing FACH congestion then definitely your user is being affected, Normally if there is FACH Congestion, RRC success rate is affected too.

Well that's a bit tricky...we can see on some sites FACH congestion (already 2 SCCPCHs) but RRC SR is above 99%; on the other hand, if u have RRC ReEst ON you can have FACH issues on some poor coverage cells.
What type of Fast Dormancy do u have? I don't have to much expertise on HW but with NSN you can limit the FACH usage by directly switch form DCH->PCH.

[saurabh.chauhan123]

Thank you for your sugestion ,second sccpch already added (in my case) .....

Anything above 40s for FAH DTCH.CONG.TIME is congestion imo.

There are many way in algo switches which you can use to reduce FACH congestion.

You can use F2D or D2F timer value adjustment, or you can also allow F2P direct. Best way is to add one more SCCPCH where ever necessary.The above formula looks a bit complicated for calculating FACH utilisation.I remember seeing a straightforward one before, but it was for RAN 13.I understand what you mean for the counter name changes in RAN14.Its a drag!