Customers getting missed call alerts yet phones are on

[kkagimu]

Hello everyone
We are experiencing a problem in our 3G network where by customers keep getting missed call alerts yet their phones are on and they have good radio conditions. What might be the cause of such a problem and what is the solution?
thanks for your help

[garry]

We need more information. Capacity stats? Is it in an in-building system? is there some active equipment at the location? Has anyone tested the paging channel? BTS vendor? Mast head amp / tower mount amp (depending what you like to call it).

Usually this happens in buildings where the Antenna system is not setup correctly. I can only assume customers are complaining about this in their offices? I've seen and am dealing with, so many cases of a lack of basic amplifier knowledge and people just running amplifiers into saturation. With repeaters and all active systems, the gain need to be correct. UMTS will not work well (if at all) if there is a big UL to DL pathloss imbalance. GSM is tolerant to pathloss indifference, but UMTS is not. And nothing will work if the Amplifier is in saturation!

If it is a passive DAS, check the UL and DL pathloss is the same (some one may have a coupler in the wrong way or other such installation faults). Easiest way to test is to get your favorite drive test kit and head to the problem area. Make a bunch of calls, and see what happens. In particular look at the UMTS UL imbalance by looking at the RACH (Random access channel) data and seeing if there are a high number of Preamble counts (on call setup) that exceed the BTS max preamble config. Or if the other way, check Initial open loop TX power is not more than the closed loop TX power. Actually, you can just get the imbalance from the BTS stats, but best to grab a log and look for all possible issues. There are many causes, but the most common are the most basic RF ones.

Before jumping to conclusions, (like I just did), check the BTS isn't showing any strange behavior.

Cheerio

[plannerguy]

Hi

Check u r paging...

it may be due to costumer moving to 2g network temp and then again camping to 3g ...so in between it may cause paging discards


Regards
Plannerguy

[Chinaman]

This could be caused by a number of issues... Pilot polution is the first one that comes to mind. When the customer is in an area with high interference, the UE cannot decode the paging message and doesn't respond to the incoming call.
Another reason could be paging congestion on the RNC, where the RNC cannot send out all paging messages, hence the call cannot be received by the UE.
To give a more specific suggestion, I'm afriad that I would need more details.....

[gprastomo]

I got this one also in my network.
Even the paging sr is acceptable.
I did trial to increase the power on prach, and it gave improvement on paging sr and there is no complaint.
you can try this also, last time i increased the contstant value

[garry]

I got this one also in my network.
Even the paging sr is acceptable.
I did trial to increase the power on prach, and it gave improvement on paging sr and there is no complaint.
you can try this also, last time i increased the contstant value

Arr, yes, if you are fiddling with the PRACH you have a problem with the link loss in the UL as compared to the DL. Too much loss in the UL and you will have to try and make the open loop power control start higher or try more times.

[elkador]

If you have good paging stats, I would suggest to check MSS and RNC.
Look for Security mode reject : could be one reason...

[electron]

Hi guys,

The problem is comming for ping pong cell IRAT reselection i experienced this problem during roll out on 3G network, Lets define some IRAT relation for the 3G cells which customer is serving by. Problem will disappear.

Cheers

[frenchy]

if the calls go straight to the voice mailbox, it could be paging congestion

this is tricky to find on NSN kit as there is no dedicated KPI

check the PCH load on your RNC, if >100% , then u have paging issues
it can be solved by the 24 kbit/s paging NSN feature (money money) or by splitting the LACs

[brianm]

Had similar problem in our network.

1. Check paging loads
2. Check Paging Delay response
3.Split the LAC - almost guarantee problem will be resolved