High PS Failure but excellent CS retainability

[tthach830]

Hi all,

I have been chasing this problem for almost a week now and could not find what the problem is:

Problem: My stat is showing very high PS drops on 3 sites; however CS failures is very low. I have check hardware and could not find any issue. The nbr sites are not affected by this stat.

This problem come and go. It also seems to go away for a day after a site restart.

This problem started a few weeks ago.
Any guidance to where else to look at would be greatly appreicated.

[MONEY]

Hi all,

I have been chasing this problem for almost a week now and could not find what the problem is:

Problem: My stat is showing very high PS drops on 3 sites; however CS failures is very low. I have check hardware and could not find any issue. The nbr sites are not affected by this stat.

This problem come and go. It also seems to go away for a day after a site restart.

This problem started a few weeks ago.
Any guidance to where else to look at would be greatly appreicated.

Run a UE trace & find out is it the Ps fail coz by single UE?
is the UL RSSI ok?
how bout CC Irat succ count?

[tthach830]

RSSI is ok. If it is then it would affect voice too.

CC IRAT Success is low;however this is normal.
The hourly stat as of today is good. I am not seeing dramatic PS retainability issue.

[anita_2k]

Hi all,

I have been chasing this problem for almost a week now and could not find what the problem is:

Problem: My stat is showing very high PS drops on 3 sites; however CS failures is very low. I have check hardware and could not find any issue. The nbr sites are not affected by this stat.

This problem come and go. It also seems to go away for a day after a site restart.

This problem started a few weeks ago.
Any guidance to where else to look at would be greatly appreicated.


Which vendor? check the attempts/traffic both for CS/PS if still normal.

[tthach830]

Which vendor? check the attempts/traffic both for CS/PS if still normal.


E///. Attemtps and traffic are normal.

HS Drops is normal too; so R99 is the culprit. I am assuming PS_Drops = HS + R99.

[chaosnoise]

E///. Attemtps and traffic are normal.

HS Drops is normal too; so R99 is the culprit. I am assuming PS_Drops = HS + R99.

Do you have Uu, Iu-ps logs? I can take a look at them if you donot mind.

[tthach830]

After further analysis, most of the drops are due to downgrading or switch from HS to R99. Most of attempts are 99% HS and less than 1% R99; however most of the PS drops are on R99.

So how do I find out what causing this R99 drops with voice accessibility/retainility are great? Is there a flowchart for how this R99 dropsped counter is pegged?

[the.rf.consultant]

try to look at what services R99 was utilizing (maybe data call) and how it is utilizing the network PS channel resources.

ultimately you have to review the RNC ChannelSwitching parameters that might have settings too stringent for the downswitching of HS to R99 causing the failure.

[tthach830]

This doesn't happened everyday. In fact it's been working fine for the last 2 days now. It's an intermitten issue.

I am now looking at the flowchart for downswitch counters and see how the counters are pegged.

Any further suggestion would be appreciated.

[adewijaya]

you have 1 carrier or 2 carrier and what kind layering strategy?

[zee86]

After further analysis, most of the drops are due to downgrading or switch from HS to R99. Most of attempts are 99% HS and less than 1% R99; however most of the PS drops are on R99.

So how do I find out what causing this R99 drops with voice accessibility/retainility are great? Is there a flowchart for how this R99 dropsped counter is pegged?

u r talking about one site or hole area
if this happen in area please check if there is any upgrade done in your area
second please check the hard handovers if you using HS and DCH loadsharing
same thing happen with me when we switched to HS and DCH loadsharing

[Kamil Koc]

Hi,

It may be a transmission problem (not physical) only you met this as R99 PS drops. If you are using ATM, there should be used AAL2PATH Logical paths with a special VPI and VCI that you should check transmissions ATM configurations for NodeB side, RNC side and transmission Elements between RNC and NodeB. I think there is a problem in logic path (AAL2PATH) definition that carries R99 PS Services.

It is same in IP transmission there are special logic paths that carry different Services. In this case you should check the VLAN in each transmission node.

[oswe]

If there´s a border, then it could be related to IUR. If it were TX problem, then you´d have the problem in Accessibility rather than in Retainability.
check if you have CELL_FACH enabled. Making drive test will certainly help a lot....

I believe is neighbor inter-RAT related.... (to be sure you need drive test)

you dont see it in CS cause you have soft handover.

[rffreeconsult]

Check your transport side. Verify if the Iub-Iur interfaces are dimensioned correctly (I would say, check your RAX board count too..but I refrain because u have written that u already verified the HW)...I have met the same kind of issues when sites with 2 C have low Drop rate (retainability in umts parlance), low accessibility but high on PS (bot drops & access). It turns out after many days of investigation that the transport pipe is not sized up enough to handle all the traffic after opto & 2C installation.