Summary
IUB congestion will cause low
CSSR of both CS and PS service. We can use NodeB counters to calculate IUB
utility ratio.
If average utility ratio is
more than 70%, IUB expansion is recommended for this site.
Related counter
We can find IUB congestion by
counters as below:
UL
IUB congestion: VS.RRC.Rej.ULIUBBandCong+VS.RAB.FailEstab.CS.ULIUBBand.Cong+ VS.RAB.FailEstab.PS.ULIUBBand.Cong+ VS.RAC.SHO.Fail.ULIub.Cong+ VS.RAC.HHO.Fail.ULIub.Cong
DL IUB congestion:
VS.RRC.Rej.DLIUBBandCong+VS.RAB.FailEstab.CS.DLIUBBand.Cong+ VS.RAB.FailEstab.PS.DLIUBBand.Cong+ VS.RAC.SHO.Fail.DLIub.Cong+ VS.RAC.HHO.Fail.DLIub.Cong
Solution
The best solution is to
expand the IUB band. Other solutions are just temporary methods to remain the KPI.
When IUB congestion is
detected, first we need check the IUB utility ratio, if utility ratio is very
small but still congestion, it may caused by wrong transmission configuration.
Usually we can modify the FTI
of the congested NodeB. MML is as follow:
1. Find the FTI of the NodeB.
ADD ADJNODE: ANI=33, NAME="nodeB",
NODET=IUB, NODEBID=1111, TRANST=ATM;
ADD ADJMAP: ANI=33, ITFT=IUB,
TRANST=ATM, CNMNGMODE=SHARE, TMIGLD=1, TMISLV=2, TMIBRZ=1, FTI=101;
2.
Change the FTI of
the NodeB to 20.
MOD ADJMAP: ANI=33, ITFT=IUB,
TRANST=ATM, CNMNGMODE=SHARE, TMIGLD=1, TMISLV=2, TMIBRZ=1, FTI=20;
Note: We configured FTI=20 dedicated for relieving the IUB
congestion. If after modification still congestion, we can also new a specific FTI.
