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Spider
2011-12-12, 09:50 PM
We faced several complaints concerning some subscribers receiving missed call alerts while connected to the network. PSR in 3G is around 91% and we are sending twice the paging based on TMSI with 8s interval. The 3G was newly launched and we need any suggestions about this issue.

Any suggestions for investigation?

louvre
2011-12-13, 01:43 AM
Due you have isho enabled if yes then check your setting for cell reselection between WCDMA and GSM.. Most of the likely hood problem is that the mobile is ping - ponging between 3G and 2G this will cause miss call and voice mail problem.. also could you be more specific about vendor. further patch / workaround can be figured out based on vendor.

Spider
2011-12-13, 03:35 AM
Thanks for your reply, actually we are with Ericsonn Utran and CN and isho is enabled, could you tell me please what are the parameters to be checked? Another Thing i checked for several cases from IU and A interface tracing that the subscriber was on 3G only.

kevin_h811
2011-12-13, 11:27 AM
Hi Spider,

Is this for one NodeB only or a cluster of NodeBs.From there you can compare settings parameters.

Regards//

Spider
2011-12-13, 04:12 PM
Hi Kevin,

The problem is that problem is very sporadic and hard to detect, that's why i'm trying to get suggestions for troubleshooting.

Br.

maahsan
2011-12-13, 06:46 PM
Try to check if this problem is related to some particular type of handset.

Spider
2011-12-13, 07:18 PM
As i said, it's sporadic and not easy to detect and based on some complaints, from Iu traces i detected that the paging was sent withtout response from the mobile, and no activity on 2G side was detected. I'm still investigating... any ideas?

plannerguy
2011-12-13, 07:39 PM
Hi

u have to look into timers for cell reselection as cells gets reselected it has do LA updation ..

so mean while u will miss paging..

Regards
Plannerguy

Moon
2011-12-15, 04:58 AM
Hi,

If you are pushing all UE in idle mode to 3G, you will end up with high number of UEs going from 3G to 2G (as your 3G layer is "small" than 2G layer), in this case & after disconnecting your calls in 2G you will need to do 2G cell reselection & LU then start measuring 3G cells; during this period of 2G cell reselection, LU (which is taking between 20 to 30 s) your UE will not be reachable. You may need to delay ISHO (EcNo to -14/-16, RSCP to -105) to minise going from 3G to 2G, also check cell reselection & make sure you are not doing Ping Pong betwen 3g to 2G (Qqualmin=-18 dB, SsearchRAT=2dB,FDDQMIN=-14,QSI=7)

Regards

Spider
2011-12-16, 07:44 PM
Actually we are implementing Directed retry, to favorize voice call on 2G layer, but i think it couldn't be the cause for this issue?

ninjafine
2012-04-15, 09:34 PM
Directed retry could be the cause if the settings is very aggressive. Imagine subscriber A calls to B saying "call me back" or something ending call in 2G due DR. B make an attempt to call but A is not reachable. One of the solution is to have common LAC in 2 and 3G.

rsv12
2012-04-16, 12:45 AM
Hi,
Check Open Loop Power Control parameters. Sometimes it could be the reason for missed calls. Do you know how many rach messages usually should be send in your network before UE get the answer from NodeB?

elkador
2012-04-16, 08:17 PM
Have you verified if complaints where coming from customers owning the same type of UE? This problem can be UE-driven as well...

sekit
2012-04-16, 10:06 PM
Try to set treselection parameter on 1s. It's e******* parameter.

Spider
2012-04-17, 11:33 AM
Back again, actually this problem was not related to some UE, from our analysis we deduced that it could be related to some paging messages discarded on RAN Level for some capacity issues, can anyone tell me what is the maximum capacity for one Node B regarding how many paging/s could be handled?

elkador
2012-04-17, 08:38 PM
Usually Paging congestion will appear per LAC. Paging Load should be less than 60%.
If not the case, then you will need to trace a missed call in the RNC and MSS. Likely a bug fix, your vendor is likely to help on this matter...

acronopio
2012-05-28, 12:56 AM
Hello:

Did you solved your issue ? , we faced a similar problem here with similar CS Paging Success Rates in fact I noticed from your post that 91% is actualy a low value we had missing calls issue under 96% .

We did a long investigation and we found out that the PS Paging was so huge that was filling up the paging channels in radio so there was no room for CS Paging ( may be that´s why you see paging coming out but there is no answer in our case that paging message was not reaching the user at all)

The main reason behind this was the use of Smartphones with Fast Dormancy Features that takes them into idle very quickly creating this huge PS Paging situation. Bottom line we took all the Iphones into private ip addresses ( and NAT of course) , this reduced the PS Paging and increased the CS Paging Success Rate and now there are no more missing calls

hope this helps
BR

Spider
2012-05-28, 01:12 AM
Hi Acronopio, thank you for your reply actually i changed work on another network! where we face low paging SR and high MP load on RNC due to signaling for paging and fast dormancy of mobiles, but i didn't understand well the solution that you did, can you give me more details on your methodology!

Reputation already given :)

acronopio
2012-05-29, 06:17 AM
Hi Acronopio, thank you for your reply actually i changed work on another network! where we face low paging SR and high MP load on RNC due to signaling for paging and fast dormancy of mobiles, but i didn't understand well the solution that you did, can you give me more details on your methodology!

Reputation already given :)


Hello Spider :

The Paging is caused by incoming traffic when the UEs are idle , meaning that if a lot of Smartphones are using Fast Dormancy and some traffic is coming in from the Internet it will create huge PS Paging traffic . In our case this situation congested the paging channels leaving no room for CS Paging and creating a Low Succes Rate for CS Paging ...our solution was simple , to avoid this incoming traffic ,how ? moving all the smartphones to private ip addressing in the GGSNs ( in the PS Core ) , so there is no way that incoming unsolicited traffic comes in. This solution requires a NAT device at the network edge (may be a Cisco Router or a Firewall in the Internet access from the operator).

We really solved the issue with this set up , and now the CS Paging success is high and there are no more missing calls anymore !

The thing here is that there is a lot of unsolicited traffic coming in from Internet ( just like in your internet router in your house) , everytime you see people trying to reach the UEs , and the UEs don´t answer most of the time but this situation will trigger paging ( to find the Smartphone that is Idle)

When you define private ip addressing for the Smatphones only solicited traffic ( meaning traffic that the Smartphone was requesting for) is allowed to get in

hope this helps

BR
Alexi

Spider
2012-05-29, 11:16 AM
Thanks a lot, i'll try to discuss this with PS core guys :)