RRC 5G UE -> gNB 3GPP TS 38.331

5G NR - Measurement Report AppLayer

Measurement Report AppLayer is the NR RRC message used by the UE to report application-layer measurements to the network.

Message Fact Sheet

Protocol	rrc	Network	5g
Spec	3GPP TS 38.331	Spec Section	5.5, 6.2.2
Direction	UE -> gNB	Message Type	Measurement Reporting

Full message name	5G NR - Measurement Report AppLayer
Protocol	RRC
Technology	5G
Direction	UE -> gNB
Interface	Uu
Signaling bearer / channel	SRB1 / UL-DCCH
Typical trigger	Used when app-layer measurement reporting has been configured and a report must be sent.
Main purpose	Provides a dedicated reporting path for configured app-layer measurements, usually when radio measurements alone are not enough.
Main specification	3GPP TS 38.331, 5.5, 6.2.2
Release added	Release 16
Procedures where used	Application-Layer Measurement Reporting, Optimization and MDT Workflows

What is Measurement Report AppLayer in simple terms?

Measurement Report AppLayer is the NR RRC message used by the UE to report application-layer measurements to the network.

Provides a dedicated reporting path for configured app-layer measurements, usually when radio measurements alone are not enough.

Why this message matters

Measurement Report AppLayer carries app-layer measurements from the UE to the network.

Where this message appears in the call flow

Application-Layer Measurement Reporting

Call flow position: Sent when the UE reports app-layer measurement results configured by the network.

Typical state: UE is in connected mode with app-layer reporting context.

Preconditions:

App-layer reporting has been configured.

Next likely message: Network optimization or service handling based on the report

Call flow position

Previous message(s): RRC Reconfiguration, Logged Measurement Configuration

Next message(s): Network-side app-layer evaluation

Message direction and transport

Sender and receiver: UE -> gNB

Interface: Uu

Domain: Access-side radio control with app-layer reporting

Signaling bearer: SRB1

Logical channel: UL-DCCH

Transport / encapsulation: Dedicated protected RRC signaling

Security context: Sent as protected connected-mode signaling.

Message Structure Overview

This is not a classic radio-measurement report. It is app-layer oriented and should be read in that context.

ASN.1 for 5G NR - Measurement Report AppLayer

MeasurementReportAppLayer ::= SEQUENCE {
  appLayerMeasurementInfo OCTET STRING
}

How to read this ASN.1

The practical difference from a normal measurement report is the source and meaning of the measurements: application-layer rather than radio-layer.

5G NR - Measurement Report AppLayer - Example Dump

UL-DCCH-Message
  message: measurementReportAppLayer
    appLayerMeasurementInfo: present

How to read this dump

Correlate the report with the configured app-layer measurement workflow, not only radio events.

Important Information Elements

IE	Required	Description
`appLayerMeasurementInfo`	Yes	Carries the application-layer measurement results reported by the UE.

Detailed field explanation

`appLayerMeasurementInfo`

Carries the application-layer measurement results reported by the UE.

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

Check that app-layer measurement reporting was configured first.
Separate app-layer reporting from radio measurement reporting in the trace.

Common Issues and Troubleshooting

The network never receives the expected app-layer report.

Likely cause: App-layer reporting may not have been configured or triggered correctly.

What to inspect: Check the earlier configuration and whether this message was sent.

Next step: Compare it with normal Measurement Report to avoid mixing the two workflows.

FAQ

How is Measurement Report AppLayer different from Measurement Report?

Measurement Report is mainly radio-layer mobility reporting, while Measurement Report AppLayer carries application-layer measurement results.

Related message pages

Related Procedures

5G RRC Reconfiguration

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.