Case 2: nCELL- Femto - UE Register Failure

Issue Description:

Same UE terminal can register under M4370, same SIM card can register under Femto when it’s installed in BTI CPE CPX60P-A, but can’t register under Femto when it’s installed in Zebra Tablets.

Though there is only 1 UE terminal is on (zebra tablet), but several UEs were observed keep trying to attach. Keep connecting and releasing.

Suggested Troubleshooting Methods:
a) Collect signal plane log to analyze.
b) Configuration parameter check by web check and xml comparation.
c) Gather log +Signal plane + FAPI log analysis.

Troubleshooting Procedures:

a) From logs, UE not responds UE capability information and gNodeB respond initial contextSetupFailure.

b) Check the configuration and compare xml files, no abnormalities were found.
c) Collect Gatherlog and signal plane logs at same time, from the log, gNb handle UE capability timeout, It could be that UE not sent out or gNodeB cant handle.

"2022/09/06 CST 11:29:17.479952 cpcellapp0[25148] DEBUG 2862690 UeState.cc:3647
UeAwaitCapability::handleUeCapabilityReTxTimeout UeId[105] crnti[7261]--------------
------------------
2022/09/06 CST 11:29:17.479952 cpcellapp0[25148] DEBUG 2862691 UeClass.h:2976
UeClass::startUeTimerEvent[UEDEFAULTTIMEOUT] with timer[RRCUECAP_TIMER: 0
seconds 500000 useconds] now"
Collect the access signal plane log of same UE terminal under M4370 for comparation.
The packet size of UE capability information is more than default MSS 1500.

M4370 not enquiry capability of EN-DC, but Femto enquiry the capability of EN-DC.
Collect the fapi3 log when pre-schedule is enabled, can observe the UE capability information were reported to gNodeB, but failed to wrap due to big package size. Need develop a new version to remove the enquiry of EN-DC capability.

After upgrade new version which remove the capability enquiry of EN-DC, UE (Zebra tablets) registered successfully.

Conclusion.
The UE Terminal supports EN-DC and Femto also enquiry the capability of EN_DC, the big size packet of UE capability information can’t be handled by existing Femto version. The latest version 5GNR_fa.tdd.fr1.2.3.0_457 has fixed it.

Please refer to Documentation for more details: Download