Disabling Direct Transition "Cell_DCH to Cell_PCH" (NSN RU30)

[Faze3]

Hello Experts,

I am facing a weird situation in my network, After disabling the direct transition from DCH to PCH, the UE is transiting as expected between the 3 stats "DCH, FACH & PCH", KPI's are showing improvement in the PS CDR, unfortunately Complaints have been increased about 0 DL throughput "mainly with USB dongles" that can be only solved by unplug and replug the dongle!!

Rolling back to direct transition activation, the complaints have been reduced as before!! Any ideas??

[djordjebeg]

Hello,

i have faced this issue as well. in fact some UEs are started looping cell_PCH-->cell_DCH and again and again until RL fails at the end.

the problem is solved partially by implementing PRFILE:
RNC_L3_Control_016 to 1.

But there are still some Ues with problem. NSN says that the problem will be fullly solve din RN6.0.2.4 ( September ) or RU40 :-(.

In RU30, RNC moves UE to Cell_PCH from Cell_DCH instead of going via FACH but some UEs have then problem although RNC is doing exactly as in the 3GPP. After state transition from Cell DCH to Cell PCH for HSPA call, if next transition is attempted from Cell PCH to Cell DCH and UE makes cell reselection same time, then the call goes into signalling loop with some UEs (CellUpdate-CellUpdateConfirm loop). The UE cannot recover from the signalling and it gets stuck until RNC releases the call. The problem is seen with certain chipset vendors only and different release UE using that chipset vendor can get stuck causing the PS throughput to stuck and finally RNC pegs drop due to UE counter.

The actual problem cannot be recovered from NW by any means. NW! can only release the RRC Connection of such UE to avoid user ! from hanging for long time.

A workaround has been made under prfile which will help in UE from not getting stuck into the signaling loop. The workaround tries to avoid the situation where UE would end up in this problem. If the prfile is active, NW will send Cell_FACH parameters to the UE during transition to Cell_PCH so that NW does not need to re-send those parameters in the scenario where UE cannot recover.

Please let me know if we can close this cas



regards,

[Faze3]

Thanks djordjebeg for the answer, but I think you are talking about the case when the Direct transition in already enabled, and so the UE goes from Cell_DCH to Cell_PCH directly. am I right?

Actually my current issue has appeared after DISABLING this Direct transition and the UE is going from Cell_DCH to Cell_FACH then to Cell_PCH, so are we talking about the same issue>?

[Faze3]

this disabling has been done through the Prfile parameter RN40_MAINT_037.

[Faze3]

Also, I couldnt find any description of the mentioned Prfile parameter, can you please send its Id or other name to search for it?

[babak1349]

Hello guys,
I am not expert in NSN but the description sounds like as a feature in E*******/ Huawei which is fast Dormancy (moving form Cell-DCH to Cell-PCH directly)
djordjebeg (http://www.finetopix.com/member.php?27247-djordjebeg) description Was pretty good. just to add someting, Cell update is done to get user to FACH state. right? as from URA-PCH user should go first to FACH and then to DCH So it might be the problem of getting user to FACH state and it can happen in highly loaded cells due to FACH/RACH overload is it the same case ?

In NSN when you are activating URA-PCH , you don't need to modify your CDR formula? Anyway drop call in URA-PCH doesn't have any meaning as there is no RAB

Cheers


Also, I couldnt find any description of the mentioned Prfile parameter, can you please send its Id or other name to search for it?

[Faze3]

Thanks Babak, The fast dormancy feature is mainly with Smart phones, my issue is with USB keys.

[saifadin]

Hi
How i can find this parameter in NSN Dump? Prfile parameter RN40_MAINT_037? or do i need MML Command?

[gaz_0001]

Hi
How i can find this parameter in NSN Dump? Prfile parameter RN40_MAINT_037? or do i need MML Command?

ZWOI to interrogate it
ZWOC to change it

You can find out more information in the the PRFILE PDF available on NOLS or NED.