What is SCG Failure Information NR r15 in LTE?
It is the uplink LTE RRC message used to report failure affecting the NR secondary cell group in an LTE master context.
| Protocol | lte-rrc | Network | lte |
|---|---|---|---|
| Spec | 3GPP TS 36.331 | Spec Section | 5.6, 6.2.2 |
| Direction | UE -> eNodeB | Message Type | Failure Reporting |
| Full message name | LTE RRC SCG Failure Information NR r15 |
|---|---|
| Protocol | LTE-RRC |
| Technology | LTE |
| Direction | UE -> eNodeB |
| Interface | Uu |
| Signaling bearer / channel | SRB1 / SRB3 / UL-DCCH |
| Typical trigger | Triggered when the UE detects failure on the NR secondary side of an EN-DC style branch. |
| Main purpose | Lets the LTE master side know that the NR secondary branch failed so EN-DC recovery, reconfiguration, or release handling can continue. |
| Main specification | 3GPP TS 36.331, 5.6, 6.2.2 |
| Release added | Release 15 |
| Procedures where used | EN-DC failure reporting, NR secondary recovery |
Uplink LTE RRC message used in E-UTRA master / NR secondary contexts when the UE reports failure affecting the NR-side secondary cell group.
Lets the LTE master side know that the NR secondary branch failed so EN-DC recovery, reconfiguration, or release handling can continue.
SCG Failure Information NR r15 tells the LTE master side that the NR secondary cell group failed.
Call flow position: UE report sent when the NR-side SCG fails in an LTE master context.
Typical state: The LTE master node learns that the NR secondary branch needs recovery or release handling.
Preconditions:
Next likely message: Later EN-DC recovery or reconfiguration
Call flow position: Failure report used by the LTE master side before deciding how to recover from NR secondary-branch problems.
Typical state: The report narrows the problem to the NR secondary side instead of the LTE master side.
Preconditions:
Next likely message: Recovery handling or NR secondary release
Previous message(s): RRCConnectionReconfiguration, EN-DC continuation
Next message(s): NR-side recovery handling, RRCConnectionReconfiguration, RRCConnectionRelease
Security context: Sent as protected connected-mode signaling.
SCGFailureInformationNR-r15 ::= SEQUENCE {
criticalExtensions CHOICE {
c1 CHOICE {
scgFailureInformationNR-r15 SCGFailureInformationNR-r15-IEs,
spare3 NULL,
spare2 NULL,
spare1 NULL
},
criticalExtensionsFuture SEQUENCE {}
}
}
Read it as an LTE-master-side failure report for the NR secondary branch.
UL-DCCH-Message
message c1 : scgFailureInformationNR-r15 : {
criticalExtensions c1 : scgFailureInformationNR-r15 : {
failureType-r15 t310-Expiry
}
}
| IE | Required | Description |
|---|---|---|
failureType-r15 | Yes | Indicates the reported NR-side SCG failure type. |
failureType-r15Indicates the reported NR-side SCG failure type.
Presence: Required
In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.
Likely cause: The UE may have reported SCG Failure Information NR r15 for the failing NR secondary branch.
What to inspect: Check the message timing, reported failure type, and later EN-DC recovery action.
Next step: Treat the issue as NR secondary failure first, not as full LTE master failure.
It is the uplink LTE RRC message used to report failure affecting the NR secondary cell group in an LTE master context.
Decode this message with the 3GPP Decoder, inspect the related message database, or open the matching call flow to see where this signaling step fits in the full procedure.