LTE RRC SCG Failure Information NR r15

Message Fact Sheet

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

What is LTE RRC SCG Failure Information NR r15 in simple terms?

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.

Why this message matters

SCG Failure Information NR r15 tells the LTE master side that the NR secondary cell group failed.

Where this message appears in the call flow

NR secondary cell group failure reporting

LTE flow showing SCG Failure Information NR r15 after NR secondary cell group failure — In an LTE master and NR secondary branch, the UE reports NR-side SCG failure so the LTE master node can continue EN-DC recovery handling.

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:

An NR secondary cell group context exists.

Next likely message: Later EN-DC recovery or reconfiguration

EN-DC failure recovery

LTE flow showing SCG Failure Information NR r15 before later EN-DC recovery handling — The message marks the NR secondary branch as failed and helps the network decide how to recover or release that EN-DC path.

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:

The UE detected failure tied to the NR SCG.

Next likely message: Recovery handling or NR secondary release

Call flow position

Previous message(s): RRCConnectionReconfiguration, EN-DC continuation

Next message(s): NR-side recovery handling, RRCConnectionReconfiguration, RRCConnectionRelease

Message direction and transport

Sender and receiver: UE -> eNodeB

Interface: Uu

Domain: Access-side radio control and EN-DC failure reporting

Signaling bearer: SRB1 / SRB3

Logical channel: UL-DCCH

Transport / encapsulation: Protected LTE RRC signaling in connected mode

Security context: Sent as protected connected-mode signaling.

Message Structure Overview

SCGFailureInformationNR-r15 is the LTE-side report for NR secondary cell group failure in EN-DC style operation.

ASN.1 for LTE RRC SCG Failure Information NR r15

SCGFailureInformationNR-r15 ::= SEQUENCE {
  criticalExtensions CHOICE {
    c1 CHOICE {
      scgFailureInformationNR-r15 SCGFailureInformationNR-r15-IEs,
      spare3 NULL,
      spare2 NULL,
      spare1 NULL
    },
    criticalExtensionsFuture SEQUENCE {}
  }
}

How to read this ASN.1

Read it as an LTE-master-side failure report for the NR secondary branch.

LTE RRC SCG Failure Information NR r15 - Example Dump

UL-DCCH-Message
  message c1 : scgFailureInformationNR-r15 : {
    criticalExtensions c1 : scgFailureInformationNR-r15 : {
      failureType-r15 t310-Expiry
    }
  }

How to read this dump

The message becomes useful when you read it against the surrounding EN-DC branch.

Important Information Elements

IE	Required	Description
`failureType-r15`	Yes	Indicates the reported NR-side SCG failure type.

Detailed field explanation

`failureType-r15`

Indicates 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.

What to check in logs and traces

Confirm that the failing side is NR secondary rather than the LTE master side.
Check the reported failure type.
Follow the later EN-DC recovery or release path.

Common Issues and Troubleshooting

The NR secondary branch drops while LTE master signaling stays alive.

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.

FAQ

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.

Related message pages

Related Procedures

Related Tools

Use This Reference in Practice

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.