RRC 5G gNB -> UE 3GPP TS 38.331

5G NR - RRC Release

RRC Release is the downlink NR RRC message used by the network to release the connected-mode context and move the UE out of active connected signaling.

Message Fact Sheet

Protocol	rrc	Network	5g
Spec	3GPP TS 38.331	Spec Section	5.3.8, 6.2.2
Direction	gNB -> UE	Message Type	Connection Release

Full message name	5G NR - RRC Release
Protocol	RRC
Technology	5G
Direction	gNB -> UE
Interface	Uu
Signaling bearer / channel	SRB1 / DL-DCCH
Typical trigger	Used when the network decides to release the active RRC connection.
Main purpose	Ends the current connected RRC context while optionally providing information relevant to idle, inactive, redirection, or release handling.
Main specification	3GPP TS 38.331, 5.3.8, 6.2.2
Release added	Release 15
Procedures where used	RRC Release, Connected-to-Idle Transition, Connected-to-Inactive Transition
Related timers	T320 when redirection or priority context applies
Related cause values	None highlighted

What is RRC Release in simple terms?

RRC Release is the downlink NR RRC message used by the network to release the connected-mode context and move the UE out of active connected signaling.

Ends the current connected RRC context while optionally providing information relevant to idle, inactive, redirection, or release handling.

Why this message matters

RRC Release tells the UE to leave the current connected RRC state.

Where this message appears in the call flow

RRC Release

Call flow position: Network command that ends the connected RRC context.

Typical state: UE is in RRC_CONNECTED.

Preconditions:

The network has decided to release or deactivate the current context.

Next likely message: Idle or inactive behavior, or later access signaling

Call flow position

Previous message(s): RRC Reconfiguration, Paging response path

Next message(s): RRC_IDLE, RRC_INACTIVE, Redirection or later access

Message direction and transport

Sender and receiver: gNB -> UE

Interface: Uu

Domain: Access-side radio control

Signaling bearer: SRB1

Logical channel: DL-DCCH

Transport / encapsulation: Dedicated protected RRC signaling

Security context: Sent as protected connected-mode signaling before the UE leaves the connected state.

Message Structure Overview

RRC Release is not always a simple drop; it can also carry redirection or inactive-related context.

ASN.1 for 5G NR - RRC Release

RRCRelease ::= SEQUENCE {
  criticalExtensions CHOICE {
    rrcRelease RRCRelease-IEs,
    ...
  }
}

How to read this ASN.1

The main engineering checks are whether the release is a plain release, an inactive-style release, or a redirection release.

Decoded Message Dump

DL-DCCH-Message
  message: rrcRelease
    suspendConfig: present

How to read this dump

The presence of suspend or redirection information changes what the UE is expected to do next.

Important Information Elements

IE	Required	Description
`redirectedCarrierInfo`	Optional	Provides redirection information if the UE should move to another carrier or system.
`suspendConfig`	Optional	Provides suspend or inactive-related information when that path is used.

Detailed field explanation

`redirectedCarrierInfo`

Provides redirection information if the UE should move to another carrier or system.

Presence: Optional

`suspendConfig`

Provides suspend or inactive-related information when that path is used.

Presence: Optional

What to check in logs and traces

Check whether the release carries suspend or redirection context.
Correlate the release with later paging, resume, or fresh setup behavior.

Common Issues and Troubleshooting

The UE is released but its later behavior looks wrong.

Likely cause: The release context may indicate a different next-state path than expected.

What to inspect: Check suspendConfig, redirection information, and the next UE action.

Next step: Follow whether the UE resumed, reselected, or started a fresh setup.

Detailed explanation

5G NR - RRC Release Explained

RRC Release is a 5G NR RRC message reference page for engineers who need to understand what the message carries, where it fits in the procedure, and what to inspect in traces when behavior does not match expectation.

RRC Release is the downlink NR RRC message used by the network to release the connected-mode context and move the UE out of active connected signaling. Ends the current connected RRC context while optionally providing information relevant to idle, inactive, redirection, or release handling.

What is RRC Release in simple terms?

RRC Release is the downlink NR RRC message the network sends to the UE when this specific procedure step needs to be controlled, configured, or completed.

Ends the current connected RRC context while optionally providing information relevant to idle, inactive, redirection, or release handling.

Why this message matters

it directly affects RRC Release, Connected-to-Idle Transition and the surrounding RRC workflow
The UE is released but its later behavior looks wrong
Used when the network decides to release the active RRC connection

Where this message appears in the call flow

RRC Release is typically seen during RRC Release. Engineers usually read it together with the messages just before and just after it so they can tell whether the procedure is progressing normally or drifting into a fallback or failure path.

The UE is usually in in RRC_CONNECTED when engineers evaluate this message in traces. In the main procedure context, it appears network command that ends the connected RRC context. Before this message appears, the important preconditions are The network has decided to release or deactivate the current context..

Simplified sequence:

UE                       gNB / Network
|                        |
|--- RRC Reconfiguration ----------->|
|<-- RRC Release -----------|
|--- RRC_IDLE ----------->|

Message direction and transport

sender: gNB
receiver: UE
interface: Uu
signaling bearer: SRB1
signaling channel: DL-DCCH
transport type: Dedicated protected RRC signaling
domain: Access-side radio control
security context: Sent as protected connected-mode signaling before the UE leaves the connected state.

Important Information Elements

IE	Why it matters
`redirectedCarrierInfo`	Provides redirection information if the UE should move to another carrier or system.
`suspendConfig`	Provides suspend or inactive-related information when that path is used.

Example message dump

DL-DCCH-Message
  message: rrcRelease
    suspendConfig: present

How to read this dump

The presence of suspend or redirection information changes what the UE is expected to do next.

FAQ

Does RRC Release always mean the UE goes idle?

Not always. It can also lead to inactive behavior or redirection depending on the included context.

Summary

RRC Release is the downlink NR RRC message used by the network to release the connected-mode context and move the UE out of active connected signaling.

Advanced Engineer Notes

The message often looks simple, but the optional release context defines what happens next.

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.