| Protocol | rrc | Network | 5g |
|---|---|---|---|
| Spec | 3GPP TS 38.331 | Spec Section | 6.2.2 |
| Direction | UE -> gNB | Message Type | Failure Reporting |
| Full message name | 5G NR - SCG Failure Information |
|---|---|
| Protocol | RRC |
| Technology | 5G |
| Direction | UE -> gNB |
| Interface | Uu |
| Signaling bearer / channel | SRB1 / SRB3 / UL-DCCH |
| Typical trigger | Used when the UE detects SCG failure or PSCell-related failure in a dual-connectivity context. |
| Main purpose | Lets the UE inform the network that the SCG failed so the network can recover, reconfigure, or release the affected dual-connectivity state. |
| Main specification | 3GPP TS 38.331, 6.2.2 |
| Release added | Release 15 |
| Procedures where used | SCG Failure Reporting, Dual Connectivity Recovery |
SCG Failure Information is the NR RRC message used by the UE to report failure related to the secondary cell group.
Lets the UE inform the network that the SCG failed so the network can recover, reconfigure, or release the affected dual-connectivity state.
SCG Failure Information tells the network that the secondary cell group failed.
Call flow position: Sent when the UE reports a failure in the secondary cell group.
Typical state: UE is in connected mode with SCG context.
Preconditions:
Next likely message: Network recovery or reconfiguration
Previous message(s): RRC Reconfiguration
Next message(s): Recovery handling, Reconfiguration, RRC Release
Security context: Sent as protected connected-mode signaling.
SCGFailureInformation ::= SEQUENCE {
failureType OCTET STRING,
...
}
Engineers use this message to connect SCG instability with later recovery actions and measurement context.
UL-DCCH-Message
message: scgFailureInformation
failureType: t310-Expiry
| IE | Required | Description |
|---|---|---|
failureType | Yes | Indicates the failure type relevant to the secondary cell group. |
measResultFreqList | Optional | Optional measurement context useful for failure analysis. |
failureTypeIndicates the failure type relevant to the secondary cell group.
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.
measResultFreqListOptional measurement context useful for failure analysis.
Presence: Optional
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 detected SCG failure and reported it.
What to inspect: Check failure type, measurements, and the later reconfiguration path.
Next step: Compare SCG Failure Information with MCG and generic failure reporting if present.
It is sent when the UE detects a failure affecting the secondary cell group.
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.