Low CS & PS CSSR due to Packet Loss Rate

[mitch_jones02]

hi guys,
wud like to ask if you encounter low CS and PS CSSR? No congestion or fails in RRC and RAB (only the most common Uu no reply).
Site is IP already. No packet loss IPPATHPING.MEANLOST or JITTER or DELAY or FWDCONG was seen.
Modified QRxLevmin but no improvement in KPI at all.
When I checked VS.IPPM.FORWORD.DROPMEANS, it shows packet loss up to 25%. When requested to NOC for checking and PING test, all is fine.
Can anybody have a resolved for this?

[rfsupp]

Please show me the counters for RRC and RAB Reject to understand better your situation.

[captain_jejemon]

We have the same issue here. We just endorse to Transport/Transmission/Microwave team.

[mitch_jones02]

We have the same issue here. We just endorse to Transport/Transmission/Microwave team.

Did you know find out the real problem is?

[fine_topix]

UU No reply can come from poor coverage UEs. Check from Call History Records if the source is one or multiple IMSIs.
Also the propagation delay if RRC attempts are coming from faraway users.

[captain_jejemon]

That is not RF part to solve transmission problem but you can check RAB access failure due to RNL. if the counts in these counter are increased mostly transmission prob.

[fine_topix]

That is not RF part to solve transmission problem but you can check RAB access failure due to RNL. if the counts in these counter are increased mostly transmission prob.

RNL: is Radio Network Layer. The transmission one is TNL: is Transmission Network Layer. Nevertheless, it worth knowing why UU interface is not responding to the RNC. If the UU interface is poor then it is normal to see loss in packets.

[mitch_jones02]

Please show me the counters for RRC and RAB Reject to understand better your situation.

I checked all the RRC/RAB reject..
For RRC, only uu no reply. For RAB, only RNL (around 12 for RAB CS and 150 for RAB PS).

I believe it's not the RNL bcoz I also encounter RNL failures before (up to 800) but the CSSR is good.

[fine_topix]

I checked all the RRC/RAB reject..
For RRC, only uu no reply. For RAB, only RNL (around 12 for RAB CS and 150 for RAB PS).

I believe it's not the RNL bcoz I also encounter RNL failures before (up to 800) but the CSSR is good.

Here, I think it is not a fair comparison to say that it is not related to radio because in the past you got 800 UU no reply and CSSR was good, because CSSR is a ratio KPI so you need to consider the number of attempts and how many out of them failed. I am afraid for your case you have low number of attempts (statistically low). Can you see the propagation delay of users? If they are faraway from the cell. Also their RSCP/EcN0/CQI distributions. Then we can isolate if it is a radio problem or not. Also you can see from RNC logs the detailed reasons for failure (not only from counters). You can consider doing a trace for users or cell level...

[mitch_jones02]

tp up to 2 only.. i mean up to around 750m. traffic is high as well. kpi good if traffic is low.

[captain_jejemon]

The site is laready IP or TDM? check IPPM Packet Loss. more than 5 % of peak forard packet loss affect CSFR and Troughput.

[mitch_jones02]

The site is laready IP or TDM? check IPPM Packet Loss. more than 5 % of peak forard packet loss affect CSFR and Troughput.

yes i agree with you. site is ip already. i only get ippm average forward packet loss and its up to 15-30%(im sure peak forward packet loss is even greater than this right?) . it greatly affects cssr.

[fine_topix]

Do you have repeaters? How is RTWP?

[mitch_jones02]

RTWP is within normal range, around -100 to -103 due to high traffic.. no repeaters!

[captain_jejemon]

yes i agree with you. site is ip already. i only get ippm average forward packet loss and its up to 15-30%(im sure peak forward packet loss is even greater than this right?) . it greatly affects cssr.

Yes it more higher. If you reduce the packet loss I'm sure CSFR will improves

[mitch_jones02]

yes that's correct.

[adriansyah]

Just try to help.

If we are sure there is problem in IP Transmission as per your mention, might be additional counter can be refer : VS.SCTP.RETX.PKGNUM / T6007:Number of Packets Resent on the SCTP Link