IRAT HO Failures (Cause: Configuration Unacceptable)

[yaserahmed25]

We are experiencing IRAT HO failures with the cause "configuration unacceptable":

- Core is HW & ZTE
- Radio is ZTE (2G & 3G) in 2 regions and HW (2G & 3G) in 3rd region
- IRAT failures occur for both CS & PS
- Failures occur for both intra and inter MSC IRAT HOs

- Some IMSI have been traced having high no of IRAT failures
- IMSI Trace in BSC & RNC were done but no difference was found in any message / configuration settings when we compared a successful & failed IRAT HO trace
- The traced UEs are SonyE******* Xperia, Samsung I8150, HTC Incredible S
- We did not find any successful IRAT HO in the traces for these IMSI

- No failures found with Sony E******* Z750 & C702 during drive tests

- One interesting aspect is that the failures disappeared after setting ciphering to A5/0 (no ciphering) at MSC end. When we set them again to A5/1, the failures appeared again.


Looking forward to a good discussion :-)

[EngSoft]

did you check insight Sharpe for HW , check if the failures from few IMSI or its a general issue. usually Config unacceptable reason happen due to IMSI problem or/and not matching in RNC-MSC setting.

after checking the fault record " from RNC " by insight Sharpe you will have a better overview.

[yaserahmed25]

We tested one IMSI with following settings:

1. With SE Xperia Ray, all 3G to 2G HOs failed (configuration unacceptable)
2. With SE C702, all 3G to 2G HOs were successful

So, it seems like handset issue and not IMSI problem.

Now,

1. What could be the configuration mismatches in RNC-MSC causing this ?
2. Can anyone confirm successful 3G to 2G HO for SE Xperia Ray in some other network ?
3. I will check re-selection (3G to 2G).
4. I still need to check Insight Sharpe.

Thanks EngSoft.

[Interface]

Base on my experience, please check the parameter set on MSC: XUDT feature at 3G MSC. If this feature are turn off( using UDT), the long message that Smart phone sent when it procedure IRAT Handover can't not decode at 2G MSC and the HO Fail.

[dacoder]

This problem usually occurs if encryption algorithm is inconsistent in 2G and 3G RAN.

[dacoder]

what is the situation now? Any improvements or still the same problem?

[yaserahmed25]

Problem resolved after enabling encryption at 3G side (integrity already enabled).

2G MSC: A5/1
3G MSC: previous UEA0 only, now UEA0 and UEA1.
SGSN: previous UEA0 only, now UEA0 and UEA1.

special thanks to dacoder!!

[yoursfraz]

Can you also please elaborate why it happens to some particular UEs? As all these UEs are new ones? any particular reason?

[Muhammad Imran Rafique]

Hi Yaserahmed,

It urgetn. Can you please give us details for

UEA0
UEA1

It is required as my back office team is asking for these details

BR//
Imran

[shamim23]

Hi Imran,

Are you interested in what they refer to? Below is semantic description:

UEA0 - The value TRUE means that an unciphered connection after the Security mode control procedure is accepted by the UE


UEA1 - The value TRUE means that UEA1, Kasumi, is supported

Hope this helps.

Thanks.

KR,
Shamim