PDA

View Full Version : Roaming Issue : 3G Ue camping forever on VPLMN



elkador
2010-07-18, 10:44 PM
Hi Experts,

Some background info : we are speaking UMTS/HSPA network here.

Anybody could bring me light on this issue :
- We have a roaming agreement with another operator (not seamless, our UE have to get out of our coverage, drop, and then register on the VPLMN).
- We set the T3212 to minimal value (6 minutes) in order to get our customers back as soon as we can.
- Problem : we are seing UEs in idle mode still camping for a very long time on the VPLMN (more than 20mins) instead of going back on the HPLMN...

Any hints to share?
Could it be UE dependant? Is there any specific parameter that could explain such a behaviour?

Thanks for your help!

kamy
2010-07-18, 10:50 PM
Hi Experts,

Some background info : we are speaking UMTS/HSPA network here.

Anybody could bring me light on this issue :
- We have a roaming agreement with another operator (not seamless, our UE have to get out of our coverage, drop, and then register on the VPLMN).
- We set the T3212 to minimal value (6 minutes) in order to get our customers back as soon as we can.
- Problem : we are seing UEs in idle mode still camping for a very long time on the VPLMN (more than 20mins) instead of going back on the HPLMN...

Any hints to share?
Could it be UE dependant? Is there any specific parameter that could explain such a behaviour?

Thanks for your help!

the fact that, you can not decide for both sides instead of the other

elkador
2010-07-18, 11:59 PM
the fact that, you can not decide for both sides instead of the other
You mean that the Roaming Operator could set a different value for the T3212 timer, and then the UE would use this value to try to register back on our network?

kamy
2010-07-19, 12:46 AM
You mean that the Roaming Operator could set a different value for the T3212 timer, and then the UE would use this value to try to register back on our network?

when you are being in someone house, you are controlled by the owner. My network is as the same yours

elkador
2010-07-19, 01:12 AM
when you are being in someone house, you are controlled by the owner. My network is as the same yours
So I guess the only way to quickly move our UEs back on our network would be to ask the Roaming Operator to disable roaming on selected sites (typically where our respective coverage overlaps)... Thanks anyway for your input, it's really appreciated!

s52d
2010-07-19, 02:19 AM
Wow, T3212 on 6 minutes, you really have empty network and happy phone charging users.
Any complains like: my batteries are gone much faster in this network compared to VPLMN?


T3212 is just "guard" parameter: if terminal is destroyed, battery removed etc, take it out of VLR.
When judging benefit of accurate VLR dB (paging success) versus signalling load/battery consumption we decided to keep it on 12 hours: some terminals just never do periodic
location area updates here.
When we suspect VLR corruption, T3212 is set to 30 minutes for a while.


Now, in real roaming, the only trigger to do PLMN reselection is loss of serving PLMN signal.
For national roaming, you can enable SIM card parameter named like HOMEPLMNSEARCH or simmilar - it tells terminals how often they should saearch for your network while camping
on another network with same MCC-MNC.

We did some tests years ago, and some terminals simply ignored this settings.

BR
s52d




Hi Experts,

Some background info : we are speaking UMTS/HSPA network here.

Anybody could bring me light on this issue :
- We have a roaming agreement with another operator (not seamless, our UE have to get out of our coverage, drop, and then register on the VPLMN).
- We set the T3212 to minimal value (6 minutes) in order to get our customers back as soon as we can.
- Problem : we are seing UEs in idle mode still camping for a very long time on the VPLMN (more than 20mins) instead of going back on the HPLMN...

Any hints to share?
Could it be UE dependant? Is there any specific parameter that could explain such a behaviour?

Thanks for your help!

elkador
2010-07-19, 02:57 AM
Wow, T3212 on 6 minutes, you really have empty network and happy phone charging users.
Any complains like: my batteries are gone much faster in this network compared to VPLMN?


T3212 is just "guard" parameter: if terminal is destroyed, battery removed etc, take it out of VLR.
When judging benefit of accurate VLR dB (paging success) versus signalling load/battery consumption we decided to keep it on 12 hours: some terminals just never do periodic
location area updates here.
When we suspect VLR corruption, T3212 is set to 30 minutes for a while.


Now, in real roaming, the only trigger to do PLMN reselection is loss of serving PLMN signal.
For national roaming, you can enable SIM card parameter named like HOMEPLMNSEARCH or simmilar - it tells terminals how often they should saearch for your network while camping
on another network with same MCC-MNC.

We did some tests years ago, and some terminals simply ignored this settings.

BR
s52d
Yup. totally agree on the battery issue. Since we are not officially commercial we can still pay this price.

Concerning the HOMEPLMNSEARCH setting : indeed it seems we have different behaviour depending of the UE (especially USB Aircard), so I was wondering if we could use an alternative way...

s52d
2010-07-19, 03:09 AM
Once again:
- T3212 is unrelated to moving of terminals
- it is SIM card parameter, on top of terminal.

Not being commercial: Wellcome to the club! It is allways fun to build new network!




Yup. totally agree on the battery issue. Since we are not officially commercial we can still pay this price.

Concerning the HOMEPLMNSEARCH setting : indeed it seems we have different behaviour depending of the UE (especially USB Aircard), so I was wondering if we could use an alternative way...

wolverine
2010-07-19, 07:19 PM
s52d is right, you should use the homePLMN timer on the SIM/USIM card to control when the handset scans for the HPLMN not T3212. If some handsets are not obeying this timer you should raise it as a defect with the supplier via your terminals dept.

elkador
2010-07-19, 11:50 PM
Just to keep you informed : the HPLMNSP is currently set to 6 min.
But we are still seing strange behaviour from the UEs...
Could it be something like :
UE would better stick to the GSM roaming network instead of going to 3G HPLMN when the HPLMNSP expires?

manson
2010-07-20, 01:11 AM
[QUOTE=elkador;92812]Hi Experts,

Please... share 3G E******* optimization cases

s52d
2010-07-20, 01:55 AM
Test with VPLMN SIM how it works for their SIMs to move to their 3G.
Same terminals, of course. Different brands(chipsets).

It might depend on BSS parameters defining when 3G is good enough to move.

Now... I recall years ago we overlooked some parameters, and users were locked to BSS
Not even ideal EcNo was good enough - but even 3GPP specs has changed, and
not many terminals are pure R99 anymore.

If you prefer measuring/experimenting to reading docs, try to compare two cases:

Case A: VPLM BSS is 20 dB better as your 3G. You have -80 dBm and excellent EcNo.

Case B: go close to your site, far from VPLM. Your pilot is stronger as VPLMN BCCH,
EcNo is excellent.

Any difference?

On top of it: even in good old W-CDMA networks, over 10% of voice calls end up on GSM.
(number_of_handovers_3g_to_2g devided with nr_of_CS_calls_on_UTRAN).

BR
s52d










Just to keep you informed : the HPLMNSP is currently set to 6 min.
But we are still seing strange behaviour from the UEs...
Could it be something like :
UE would better stick to the GSM roaming network instead of going to 3G HPLMN when the HPLMNSP expires?

boring
2010-07-20, 02:19 AM
Just to keep you informed : the HPLMNSP is currently set to 6 min.
But we are still seing strange behaviour from the UEs...
Could it be something like :
UE would better stick to the GSM roaming network instead of going to 3G HPLMN when the HPLMNSP expires?

when this timer expires it forces the UE to do (home)PLMN selection which means that UE must find a suitable cell to camp. hence the cell must meet minimum RSCP and EcNo requirements.

in your cases, are you sure 3G radio is sufficient to camp?

elkador
2010-07-20, 03:50 AM
HPLMN 3G network is definitively good at our test point : we are supplying dedicated inbuilding coverage. I would say Ec = -80 dBm, Ec/No = -7dB.

We just found some interesting stuff : one UE (garmin not to name it) was having a hidden PDP context activated on the VPLMN with data, When we switched offf manually in the UE data connection, it went straight to our network...

boring
2010-07-20, 04:00 AM
this PDP context changes everything because UE now follows 2G-3G cell reselection which means that 3G must be better than 2G (assuming default params setting) before going to 3G...

very interesting case...

thanh_qlktnv
2010-12-25, 11:09 PM
Someone can suggest us for national roaming. My subscriber still camp on VPLMN more than 1 hour. I am sure HPMNSP=6 minutes.May be 2G -3 G cell selection is accounted for that problem ?
Here link for useful roaming Roaming (http://www.scribd.com/doc/36740489/Roaming)
Someone can give a hint
By the way How I can download some useful docs here? Pls help me.

leo.ashu
2010-12-26, 01:54 PM
T3212 is for periodic locn update. There is another timer for Home PLMN selection. You may set that to 6 minutes(not setting would mean the Home PLMN timer = 30mins). Periodic Locn update timer value = 6 mins is absurd. Home PLMN selection timer = 6 minutes is working fine in many networks with Intra circle roaming agreements.

zhanglw268
2010-12-26, 07:57 PM
The timer VPLMN T is programed at the USIM, not a timer controlled by RNC SIBs, Also T3212 at your network can only control the mobile when it is in your network, when the Mobiles move to VPLMN, they are controlled by VPLMN's T3212, this T3212 won't help you to move back to HPLMN.

What you can do to reduce the roaming to VPLMN is to modify certain parameters at 3G to make the cell resection more difficult. These parameters are:
SsearchRATm,Qrxlevmin ,Qqualmin and Treselections.

You can set the first 3 parameters to minimum value and set the Treselections larger, this might ease the situation but it won't control the roaming times which mobiles spend at the VPLMN.

As the VPLMN is a mature network, you can talk/discuss with VPLMN engineers to make the 3G cell reselection more easily by setting FDD_Qmin and FDD_QOFFSET lower, qsearch_i to 7 (always searching 3G) if you have only one-way roaming agreement, otherwise VPLMN won't want their mobiles roaming in your network.

The best way is to program the USIM VPLMN T timer to 6 minutes etc. to let mobiles reselect back to HPLMN more quickly once they are in VPLMN.

Regards

Zhanglw268

Someone can suggest us for national roaming. My subscriber still camp on VPLMN more than 1 hour. I am sure HPMNSP=6 minutes.May be 2G -3 G cell selection is accounted for that problem ?
Here link for useful roaming Roaming (http://www.scribd.com/doc/36740489/Roaming)
Someone can give a hint
By the way How I can download some useful docs here? Pls help me.

thanh_qlktnv
2010-12-27, 11:02 AM
hi, Zang

Thanks for your quick reply. I wonder HPLMNSP -6 minutes and VPMLN T ? when my subscriber roaming into VPLMN- 2G network after 6 minutes my subs will search HPLMN but nothing happen. Maybe after 6 minutes my subscriber check my 3G network but not enough to return my 3G network. 2G 3G cell reselection and PLMN selection ??? what is first ?

thanh_qlktnv
2010-12-27, 12:42 PM
hi,all
We just found down something. If subscriber roaming into 3G VPLMN then VPLMN send a "LA not allow", CELL selection takes places not PLMN selection. We will check and let you know.

zhanglw268
2010-12-28, 09:06 PM
I guess that you think HPLMNSP is the VPLMN T, from the scenario that you described, I have doubt that they are the same. It is most likely that the timer T for searching HPLMN isn't programmed on the USIM so the default value is 60 minutes per the 3GPP Specs, the reason is that you said that the mobile would come back to your network around 60 minutes. Anyway, you need to set this value to a proper value when system is launched to reserve the Mobile battery life.

Regarding PLMN re-selection or cell recelection, The mobile will do the cell reselection first if the HPLMN selection timer doesn't time out. If the HPLMN selection timer is timeout, the PLMN selection will be first.

As you are in the test stage of the system launch, I would suggest that you try to find out what reasons caused mobiles going to VPLMN at the first place, like lost coverage temporarily due to NodeB link down, alarms, RNC, MSC/VLR and HLR etc. problems, then address them, then the UE camping on VPLMN issue will be reduced or disappeared if the system becomes stable.

Regards

Zhanglw268


hi, Zang

Thanks for your quick reply. I wonder HPLMNSP -6 minutes and VPMLN T ? when my subscriber roaming into VPLMN- 2G network after 6 minutes my subs will search HPLMN but nothing happen. Maybe after 6 minutes my subscriber check my 3G network but not enough to return my 3G network. 2G 3G cell reselection and PLMN selection ??? what is first ?

luganomu
2010-12-31, 03:38 PM
Hi expert

here is my roaming issue, in my network we are using NSN( Nokia flex) when roamer came to our network they are able to hook to our net but it is impossible to make call, what could be a problem

thanks in advance

zhanglw268
2011-01-04, 11:54 PM
Hi expert

here is my roaming issue, in my network we are using NSN( Nokia flex) when roamer came to our network they are able to hook to our net but it is impossible to make call, what could be a problem

thanks in advance
What does your "hook" mean? Do you mean that the mobile camps on the cell freely or with limited access ?