UMTS IFHO Analysis from DT and related parameters

[theumar@hotmail.com]

Dear All,

Please help in questions relating IFHO DT analysis and related controlling parameters in Huawei.

In our network we are testing a scenario temporarily to rule out external interference case and there is IFHO border between F1 of RNC1 and F1 of RNC2.
Initially IFHO was disabled but for this trial we have enabled IFHO between border cells.

While analyzing logfiles to check if HHO performance is fine, it was observed commonly that call dragged on border cells and even it enters into 2nd tier without triggering compressed mode. Event2DRSCP threshold for CS/PS is -95 and -92 and ECIO for CS/PS is -14 and -12 respectively and border is at urban/suburban mix area where average intersite distance is around 700 to 800m). Questions that I am unable to find answers are

1. From DT layer 3 messages after compressed mode activation, RNC sends measurement control message. My understanding is that RNC transfer the NBR cells info including PSC of nbrs to active cell for measurement. For the above mentioned case I am unable to find the specific target cell PSC xxx in that layer3 measurement control message. PSC xxx cell is defined as interfrequency nbr.

2. Is it possible if we can restrict compressed mode initiation based on RSCP or EcIo?

3. How to check what gsm cells and interfrequency cells UE is monitoring?

Thanks,

Ha3k

[mihail]

Dear All,

Please help in questions relating IFHO DT analysis and related controlling parameters in Huawei.

In our network we are testing a scenario temporarily to rule out external interference case and there is IFHO border between F1 of RNC1 and F1 of RNC2.
Initially IFHO was disabled but for this trial we have enabled IFHO between border cells.

While analyzing logfiles to check if HHO performance is fine, it was observed commonly that call dragged on border cells and even it enters into 2nd tier without triggering compressed mode. Event2DRSCP threshold for CS/PS is -95 and -92 and ECIO for CS/PS is -14 and -12 respectively and border is at urban/suburban mix area where average intersite distance is around 700 to 800m). Questions that I am unable to find answers are

1. From DT layer 3 messages after compressed mode activation, RNC sends measurement control message. My understanding is that RNC transfer the NBR cells info including PSC of nbrs to active cell for measurement. For the above mentioned case I am unable to find the specific target cell PSC xxx in that layer3 measurement control message. PSC xxx cell is defined as interfrequency nbr.

2. Is it possible if we can restrict compressed mode initiation based on RSCP or EcIo?

3. How to check what gsm cells and interfrequency cells UE is monitoring?

Thanks,

Ha3k

Hi theumar@hotmail.com,

From what you have mentioned initially you are not speaking about IFHO, you are rather speaking about IntraFreq HHO on the same Frequency F1 betwoeen cells belonging to two different RNCs (RNC1 and RNC2) which do not have an Iur connection between them. Please precize if this is your case or not. More exactelly the border cells from one RNC (RNC1) are working on frequency F1 but the other border cells belonging to RNC2 are working on the same frequency F1 or on a different frequency F2? If the cells belonging to RNC2 are working on different frequency F2 then you should have a standard InterFrequency HHO process in place but if it is the same Frequency F1 then you should have a normal SHO if there is an Iur link between RNC1 and RNC2 or a HHO between one border cell (A) belonging to RNC1 and another border cell (B) belonging to RNC2 if there is no Iur between RNC1 and RNC2. So what is your case?!

[theumar@hotmail.com]

thank you mihail for replying, RNC1 ARFCN is different and RNC2 F1 ARFCN is different, there is no SHO at RNC boundary happening at the moment.

[mihail]

thank you mihail for replying, RNC1 ARFCN is different and RNC2 F1 ARFCN is different, there is no SHO at RNC boundary happening at the moment.

Hello theumar,

Once again I guess it is a wrong usage of the standard terms used by you, therefore you need to be more precised.

In 2G it should be used the term of ARFCN (BCCH) while in 3G you should use the term UARFCN (that is the UMTS Absolute Frequency Channel Number).

You need to precize if the UARFCN (F1) used for RNC1 is the same or different with the UARFCN (F2) used in RNC2.

After you precise if F1=F2 or F1<>F2 then we may understand better your case...

[theumar@hotmail.com]

:( sorry mihail for confusing things, I meant UARFCN here and F1 <> F2, for example assume that there is only one carrier in network and RNC1 cells is operating at XXXXX while RNC2 cells operating at YYYYY UARFCNs and both these RNCs are part of same PLMN and adjacent to each other.

Recently I drive tested RNC border by moving from RNC1 to RNC2 to check IFHO performance and observed that in some cases call dragged even near RNC2 cells, UE was connected to RNC1 cell and finally IRAT HO triggered, but logically IFHO should triggered before? I want to see RSCP and EcIo of IF NBR cell of RNC2 but I can not find option to check it Genex Assistant.

[mihail]

Hi theumar,

The things are clear now; you should have a standard InterFrequency HHO process when the UE should be in compressed mode before HHO and deliver the measurements reports [containing the values of EcNo / RSCP from the cells belonging to RNC2 (when moving from RNC1 to RNC2)].

What you should verify in the first instance:
1) Check that the cells belonging to border RNC2 are declared as neighbors to the border cells belonging to RNC1;
2) Check which are the thresholds values for e2d / e2f (for EcNo and RSCP) which are triggering the "alarm" criteria that means when the mobile should enter into compressed mode (CM) in order to measure the cells from the other frequency;
3) If you have the drive test log file from the UE you may check the list of the cells neighbors related to RNC2 which RNC1 is transmitting to the UE (while still under RNC1 cell coverage) before the command of entering into CM; this info you should see into the DL "measurement control" message received by the mobile before entering into CM;

In case you want to trigger quickly the IFHO while moving from RNC1 to RNC2 you should modify the e2d/e2f theresholds associated to the border cells; example EcNo: -12/-10, RSCP: -90/-85

I hope this may help you...