[UMTS] PS drops on cell reselection

[pUbLIS]

Hello to all RF gurus

I have a doubt that maybe some of you can help me.

I've just got a case of a nB that apparently has a high drop on PS calls on cell reselection.
I've been reading about cell reselection and, as far as I can understand, its a simple handover due to better conditions (radio measurements) on a neighbor cell.

Am I right? Is it a simple HO?

This was what I came up with (@ http://www.umtsworld.com/technology/RCC_states.htm)

States and procedures in the cell reselection process in connected mode

When a cell reselection is triggered, the UE evaluates the cell reselection criteria based on radio measurements, and if a better cell is found that cell is selected, procedure Cell reselection. If the change of cell implies a change of radio access technology, the RRC connection is released, and the UE enters idle mode of the other RAT. If no suitable cell is found in the cell reselection procedure, the UE eventually enters idle mode.

When an Initial cell reselection is triggered, the UE shall use the Initial cell reselection procedure to find a suitable cell. One example where this procedure is triggered is at radio link failure, where the UE may trigger an initial cell reselection in order to request re-establishment of the RRC connection. If the UE is unable to find a suitable cell, the UE eventually enters idle mode.

Cheers

[pUbLIS]

after reading a bit more, apparently it is called "cell reselection" just when passing from UMTS to GSM... is that it?

[Tomas Delgado]

Cell Selection and Reselection only happens if you are in iddle mode, you can select and reselect to a WCDMA cell or reselect to GSM depending on conditions. Handover applies when you are in connected mode.

[pUbLIS]

So... if the reselection happens whenever in idle mode, is impossible to have a drop in that state.

None the less.. I was able to get the RNC counter in which he based his complain:


HS-DSCH Release due to RL failure for interactive..

.. any thoughts?

[pUbLIS]

This is a description of the counter:

[dNoB]

This is a description of the counter:

... seems the user was web-browsing before the failure occured...

[mail2knrp]

Cell reselection and handover both happens to find the better cell.
Assuming the UMTS case,just want to clarify one thing:

Cell Reselection can happen in :
- IDLE (idle mode - no RRC connection)
- Connected mode (CELL_PCH,URA_PCH,CELL_FACH)

Hand Over can happen in CELL_DCH, where you have RRC connection.

After reading the original ticket content,my understaning is that UE must be in CELL_FACH where it might be doing some packet transmission inthe meantime,UE might forced to do a cell reselection(after the weighting factor Treselection FACH time waited).

To answer the radio link failure:
When UE drops a call due to radio link failure, UE shall do a cell reselection,find a better cell and do a cell update with cause (radio link failure) so that the re-establishment can be tried to continue the call.

[finetopicbooks]

If the UE succeeds to re-establish the call through cell_update on a reselected cell, the call is considered to be normal release...and this is how we see improvement in call drop number when we implement RL-Re Establishment feature.