RRC 5G UE -> gNB 3GPP TS 38.331

5G NR - UECapabilityInformation

Uplink NR RRC message used by the UE to report its supported radio capability containers to the gNB.

Message Fact Sheet

Protocol	rrc	Network	5g
Spec	3GPP TS 38.331	Spec Section	5.6.1, 6.2.2, Annex B.1
Direction	UE -> gNB	Message Type	Capability Exchange

Full message name	5G NR - UECapabilityInformation
Protocol	RRC
Technology	5G
Direction	UE -> gNB
Interface	Uu
Signaling bearer / channel	SRB1 / UL-DCCH
Typical trigger	The UE responds to UECapabilityEnquiry by returning the requested capability containers.
Main purpose	Transfers UE radio capability information so the network can build configuration that matches the UE's supported NR features.
Procedures where used	UE Capability Transfer, Connected-Mode Capability Discovery, Capability-Aware RRC Reconfiguration
Related timers	Procedure-specific connected-mode supervision context
Related cause values	No reject cause IE is carried in UECapabilityInformation, Troubleshooting usually depends on capability completeness, parser behavior, and the later network action
Main specification	3GPP TS 38.331, 5.6.1, 6.2.2, Annex B.1

What this message does in simple terms

Uplink NR RRC message used by the UE to report its supported radio capability containers to the gNB.

Transfers UE radio capability information so the network can build configuration that matches the UE's supported NR features.

Why this message matters

UECapabilityInformation is the UE's answer to the network's capability request. It tells the gNB what radio features the UE supports.

Where this message is used

UE Capability Transfer

Call flow position: UE response that carries the requested capability containers back to the gNB.

Typical state: UE is in RRC_CONNECTED and able to return capability information on protected DCCH signaling.

Preconditions:

The gNB sent UECapabilityEnquiry.
The UE can assemble the requested capability information.

Next likely message: Capability-dependent RRCReconfiguration or another network decision based on the reported support

Capability-Aware RRC Reconfiguration

Call flow position: Capability report that the network uses before applying feature-dependent radio configuration.

Typical state: UE is connected and the network is validating supported features before changing configuration.

Preconditions:

The network requested the relevant RAT capability containers.

Next likely message: RRCReconfiguration

Full Procedure Context

Previous message(s): UECapabilityEnquiry

Next message(s): RRCReconfiguration, Capability-aware connected-mode network decision

Message Direction and Transport

Sender and receiver: UE -> gNB

Interface: Uu

Domain: Access-side radio control capability reporting

Signaling bearer: SRB1

Logical channel: UL-DCCH

Transport / encapsulation: RRC over DCCH on SRB1 during connected-mode capability exchange

Security context: Typically exchanged after AS security is active, so it is usually carried as protected connected-mode RRC signaling.

Message Structure Overview

UECapabilityInformation is the payload-heavy half of the capability exchange because it carries the actual reported capability containers.
The key engineering task is to identify which RAT containers are present and whether the reported support matches the later network configuration.
This message should always be interpreted together with the earlier UECapabilityEnquiry and the later capability-dependent RRC behavior.

ASN.1 for 5G NR - UECapabilityInformation

UECapabilityInformation ::= SEQUENCE {
  rrc-TransactionIdentifier RRC-TransactionIdentifier,
  criticalExtensions CHOICE {
    ueCapabilityInformation UECapabilityInformation-IEs,
    criticalExtensionsFuture SEQUENCE {}
  }
}

UECapabilityInformation-IEs ::= SEQUENCE {
  ue-CapabilityRAT-ContainerList UE-CapabilityRAT-ContainerList,
  lateNonCriticalExtension       OCTET STRING OPTIONAL,
  nonCriticalExtension           SEQUENCE {} OPTIONAL
}

How to read this ASN.1

Most of the practical value is inside the returned RAT capability containers. Engineers should inspect what RAT capability blocks are present and whether the network later interprets them correctly.

Decoded Message Dump

UL-DCCH-Message
  message: ueCapabilityInformation
    rrc-TransactionIdentifier: 3
    criticalExtensions:
      ueCapabilityInformation:
        ue-CapabilityRAT-ContainerList:
          - rat-Type: nr
            ueCapabilityRAT-Container: <NR UE Capability container>
        lateNonCriticalExtension: absent
        nonCriticalExtension: absent

How to read this dump

The important part is the returned RAT capability container list.
In practical traces, the NR capability container can be large and deeply structured.
If later configuration fails, compare the network decision against what the UE actually reported here.

Information Elements

IE	Required	Description
`rrc-TransactionIdentifier`	Yes	Transaction identifier used to correlate the UE response with the preceding UECapabilityEnquiry.
`ue-CapabilityRAT-ContainerList`	Yes	List of UE capability containers reported by the UE for the requested RATs.
`lateNonCriticalExtension`	Optional	Extension container used for later release evolution and compatibility handling.
`nonCriticalExtension`	Optional	Forward-compatible extension branch for later additions.

Detailed field explanation

`rrc-TransactionIdentifier`

Transaction identifier used to correlate the UE response with the preceding UECapabilityEnquiry.

Presence: Required

`ue-CapabilityRAT-ContainerList`

List of UE capability containers reported by the UE for the requested RATs.

Presence: Required

`lateNonCriticalExtension`

Extension container used for later release evolution and compatibility handling.

Presence: Optional

`nonCriticalExtension`

Forward-compatible extension branch for later additions.

Presence: Optional

What to check in logs and traces

Confirm the message follows UECapabilityEnquiry and uses SRB1 / UL-DCCH.
Verify the transaction identifier matches the preceding enquiry.
Inspect which RAT capability containers are present.
Check whether the reported capability content is complete and consistent with the scenario.
Correlate the message with the following RRCReconfiguration or other network action.

Common Issues and Troubleshooting

UECapabilityInformation is present but later feature configuration fails.

Likely cause: The network may have misread or misused the reported capability data, or the UE report may be incomplete for the intended feature.

What to inspect: Compare the returned capability containers with the later RRCReconfiguration content.

Next step: Validate that the configured features are actually declared as supported in the UE report.

Capability reporting looks incomplete or missing expected containers.

Likely cause: The enquiry may not have requested the full set needed, the decoder may be incomplete, or the UE may not report the expected capability data.

What to inspect: Check UECapabilityEnquiry first, then compare the requested and returned RAT lists.

Next step: Confirm whether the missing container is truly absent or just not decoded in the current toolchain.

Repeated capability exchange occurs.

Likely cause: The network may be revalidating capability context after context loss, mobility, or implementation-specific behavior.

What to inspect: Check whether the repeated exchange corresponds to a new connected-mode context or procedure restart.

Next step: Determine whether the repeat procedure is expected before treating it as abnormal.

Detailed explanation

5G NR - UECapabilityInformation Message Explained

The UECapabilityInformation message is the NR RRC message the UE uses to report its supported radio capability information back to the gNB in 5G NR.

In simple terms, this is the UE answering the network’s capability question and saying: these are the radio features and capability containers I support.

Why UECapabilityInformation matters

UECapabilityInformation is important because it gives the network the actual data it needs before building capability-dependent configuration.

It matters because it helps the gNB:

confirm UE feature support
avoid unsupported radio configuration
prepare correct connected-mode reconfiguration
troubleshoot capability mismatches using real UE-reported data

If this message is wrong, incomplete, or misinterpreted, the visible failure often shows up later in RRC Reconfiguration.

Where UECapabilityInformation appears in the call flow

A common capability-aware connected-mode path is:

SecurityModeComplete confirms AS security activation
UECapabilityEnquiry from gNB to UE
UECapabilityInformation from UE to gNB
RRC Reconfiguration based on reported support

This means UECapabilityInformation is the practical payload stage of the capability exchange.

Call flow position

UE                               gNB
|                                |
|<---- UECapabilityEnquiry ------|
|                                |
|---- UECapabilityInformation -->|
|                                |
|<------ RRCReconfiguration -----|
|                                |

This sequence shows the normal flow:

UECapabilityEnquiry requests the capability data
UECapabilityInformation returns the UE-reported capability containers
RRC Reconfiguration uses that information to apply supported configuration

Practical troubleshooting guidance

This message is best analyzed together with:

If a later feature configuration fails, the main engineering questions are:

what exactly did the UE report?
did the returned RAT capability containers match what the gNB requested?
did the later reconfiguration respect the reported UE support?

5G NR - UECapabilityEnquiry for the network-side request that starts this exchange
5G NR - RRC Reconfiguration for the later capability-dependent configuration step

Summary

UECapabilityInformation is the UE-side report that carries the actual capability data in the NR RRC capability exchange.

The key engineering points are:

it carries the reported UE capability containers
it answers UECapabilityEnquiry
it often influences the next RRCReconfiguration
it is one of the best places to validate what the UE really declared as supported

FAQ

What does UECapabilityInformation do in 5G NR?

It reports the UE's radio capability information back to the gNB.

Who sends UECapabilityInformation?

The UE sends UECapabilityInformation to the gNB.

What comes before UECapabilityInformation?

UECapabilityEnquiry normally comes immediately before it.

Why is UECapabilityInformation important?

It gives the network the capability data needed to build configuration that the UE can actually support.

Does UECapabilityInformation affect later RRCReconfiguration?

Yes. The reported capabilities often directly influence what the network configures next.

Summary

Uplink NR RRC message used by the UE to report its supported radio capability containers to the gNB.

Advanced Engineer Notes

This page is often more valuable than the enquiry page because the actual reported support appears here.
Large capability containers are easy to decode incorrectly, so tooling and parser confidence matter.
Many advanced feature failures trace back to a mismatch between what the UE reported here and what the gNB tried to configure later.

LTE / 5G / Variant Comparison

Compared with UECapabilityEnquiry

UECapabilityEnquiry asks for capability data. UECapabilityInformation carries the actual UE-reported capability containers.

Related Messages

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.

5G NR - UECapabilityInformation

Message Fact Sheet

What this message does in simple terms

Why this message matters

Where this message is used

UE Capability Transfer

Capability-Aware RRC Reconfiguration

Full Procedure Context

Message Direction and Transport

Message Structure Overview

ASN.1 for 5G NR - UECapabilityInformation

How to read this ASN.1

Decoded Message Dump

How to read this dump

Information Elements

Detailed field explanation

rrc-TransactionIdentifier

ue-CapabilityRAT-ContainerList

lateNonCriticalExtension

nonCriticalExtension

What to check in logs and traces

Common Issues and Troubleshooting

UECapabilityInformation is present but later feature configuration fails.

Capability reporting looks incomplete or missing expected containers.

Repeated capability exchange occurs.

Detailed explanation

5G NR - UECapabilityInformation Message Explained

Why UECapabilityInformation matters

Where UECapabilityInformation appears in the call flow

Call flow position

Practical troubleshooting guidance

Related message pages

Summary

FAQ

What does UECapabilityInformation do in 5G NR?

Who sends UECapabilityInformation?

What comes before UECapabilityInformation?

Why is UECapabilityInformation important?

Does UECapabilityInformation affect later RRCReconfiguration?

Summary

Advanced Engineer Notes

LTE / 5G / Variant Comparison

Compared with UECapabilityEnquiry

Related Messages

Related Procedures

Related Tools

Use This Reference in Practice

`rrc-TransactionIdentifier`

`ue-CapabilityRAT-ContainerList`

`lateNonCriticalExtension`

`nonCriticalExtension`