Problem PS-IRAT 3G (//E W11A) to 2G (HWI R8.1)

We have found the problem of Inter-RAT PS handover success rate from E******* 3G900 to Huawei 2G900. The success rate in Huawei 2G900 area is low (50%) compare with E******* 2G900 area (>85%) in terms of statistics. From drive test, we have found that data service resume in Huawei 2G900 after Inter-RAT PS handover take very long time and sometime data fail to resume compare with data resume in E******* 2G900.
***problems will generate only DTM mobile***

case normal: PS-IRAT 3G (//E) to 2G (//E) is normal step by (with on DTM in 2G, So that LA and RA send follow)

Cell Change Order From UTRAN (DL-DCCH)
Location Updating Request
Immediate Assignment
Classmark Change
Routing Area Update Request
Routing Area Update Request
Classmark Enquiry
Classmark Change
Authentication Request
Authentication Response
Ciphering Mode Command
Ciphering Mode Complete
Routing Area Update Accept
Routing Area Update Complete
Routing Area Update Complete
Location Updating Accept

case not success: PS-IRAT 3G (//E) to 2G (HWI) step by (with on DTM in 2G, So that LA and RA send follow)

Cell Change Order From UTRAN (DL-DCCH)
Location Updating Request
Immediate Assignment
Classmark Change
Routing Area Update Request
Routing Area Update Request
Classmark Enquiry
Classmark Change
Authentication Request
Authentication Response
Ciphering Mode Command
Ciphering Mode Complete
Location Updating Accept

it does not have routing area Accept , so that UE have very long time to retry "Routing Area Update Request".

I can not found "Routing Area Update Request" in 2G-SGSN, I thing BSC does not forward "Routing Area Update Request" to 2G-SGSN.

thank you
aomma

try to tapping GB interface from BSC to SGSN check any routing area update request or not

Hi aomma,
you didn't mention whether the 50% successfull 3G//E -> 2G H has the same sequence than the 3g//E -> 2G//E
Does the //E have its own SGSN ? and thus an inter SGSN handover involved?
Is there SGSN in pool? 50% is such a leading number, are the Routing Areas defined on both?

slán, framesynch