LTE - RRCConnectionReconfigurationComplete

Message Fact Sheet

Protocol	lte-rrc	Network	lte
Spec	3GPP TS 36.331	Spec Section	5.3.5, 6.2.2
Direction	UE -> eNodeB	Message Type	Connected-mode Control

Full message name	LTE - RRCConnectionReconfigurationComplete
Protocol	LTE-RRC
Technology	LTE
Direction	UE -> eNodeB
Interface	Uu
Signaling bearer / channel	SRB1 / UL-DCCH
Typical trigger	The UE successfully applies RRCConnectionReconfiguration and is ready to acknowledge the update.
Main purpose	Confirms that the UE applied the connected-mode LTE RRC reconfiguration so the network can continue with the updated bearer, measurement, mobility, or handover path.
Main specification	3GPP TS 36.331, 5.3.5, 6.2.2
Release added	Release 8
Procedures where used	Connected-mode Reconfiguration, Measurement Control, LTE Handover, Bearer Modification
Related timers	T304 in handover-related cases
Related cause values	There is no reject cause in this success-path message

What is RRCConnectionReconfigurationComplete in simple terms?

Uplink LTE RRC message sent by the UE to confirm successful handling of RRCConnectionReconfiguration.

Confirms that the UE applied the connected-mode LTE RRC reconfiguration so the network can continue with the updated bearer, measurement, mobility, or handover path.

Why this message matters

RRCConnectionReconfigurationComplete is the UE telling the network that the LTE connected-mode update was applied successfully.

Where this message appears in the call flow

Connected-mode continuation

LTE connected-mode flow showing RRCConnectionReconfiguration, RRCConnectionReconfigurationComplete, and later connected signaling — In connected-mode continuation, RRCConnectionReconfigurationComplete confirms that the LTE update was applied before later signaling continues.

Call flow position: UE confirmation message sent after a connected-mode radio update.

Typical state: UE is in RRC_CONNECTED and has applied the received configuration.

Preconditions:

RRCConnectionReconfiguration has been received.
The UE could apply the populated configuration blocks successfully.

Next likely message: Later connected-mode signaling using the updated configuration

LTE handover

Call flow position: Completion step used after mobility-related reconfiguration in handover cases.

Typical state: UE is in connected mode and is confirming that the mobility-related update was applied.

Preconditions:

The handover-related reconfiguration was received.
The UE could proceed with the mobility update.

Next likely message: Target-side continuation or later connected signaling

Call flow position

Previous message(s): RRCConnectionReconfiguration

Next message(s): Later connected-mode LTE RRC signaling, Target cell continuation in handover-related cases

Message direction and transport

Sender and receiver: UE -> eNodeB

Interface: Uu

Domain: Access-side radio control

Signaling bearer: SRB1

Logical channel: UL-DCCH

Transport / encapsulation: RRC over DCCH on SRB1 in connected mode

Security context: Normally carried after LTE AS security activation, so it confirms completion of protected dedicated LTE RRC signaling.

Message Structure Overview

RRCConnectionReconfigurationComplete is a compact confirmation message.
Its main practical value is correlation with the earlier reconfiguration and the procedure state that follows.
If this message is missing, the network should not assume the connected-mode update completed successfully.

ASN.1 for LTE - RRCConnectionReconfigurationComplete

RRCConnectionReconfigurationComplete ::= SEQUENCE {
  rrc-TransactionIdentifier RRC-TransactionIdentifier,
  criticalExtensions CHOICE {
    c1 CHOICE {
      rrcConnectionReconfigurationComplete-r8 RRCConnectionReconfigurationComplete-r8-IEs,
      spare3 NULL,
      spare2 NULL,
      spare1 NULL
    },
    criticalExtensionsFuture SEQUENCE {}
  }
}

RRCConnectionReconfigurationComplete-r8-IEs ::= SEQUENCE {
  nonCriticalExtension RRCConnectionReconfigurationComplete-v8a0-IEs OPTIONAL
}

How to read this ASN.1

The main analysis path is transaction correlation with RRCConnectionReconfiguration and the updated connected-mode behavior that follows.

Decoded Message Dump

UL-DCCH-Message
  message c1 : rrcConnectionReconfigurationComplete : {
    rrc-TransactionIdentifier 3,
    criticalExtensions c1 : rrcConnectionReconfigurationComplete-r8 : {
    }
  }

How to read this dump

The transaction identifier should match the preceding reconfiguration.
This message is structurally simple, so its practical value comes from sequence position and what follows after it.
In handover-related cases, correlate it with the target-side continuation.

Important Information Elements

IE	Required	Description
`rrc-TransactionIdentifier`	Yes	Transaction identifier matching the preceding RRCConnectionReconfiguration.
`criticalExtensions`	Yes	Versioned wrapper carrying the completion payload.
`nonCriticalExtension`	Optional	Release-extension branch used for later additions.

Detailed field explanation

`rrc-TransactionIdentifier`

Transaction identifier matching the preceding RRCConnectionReconfiguration.

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.

`criticalExtensions`

Versioned wrapper carrying the completion payload.

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.

`nonCriticalExtension`

Release-extension branch used for later additions.

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.

What to check in logs and traces

Confirm the message follows RRCConnectionReconfiguration.
Verify the transaction identifier matches the reconfiguration message.
Check whether later connected behavior reflects the newly applied configuration.
In mobility cases, correlate it with the handover continuation.

Common Issues and Troubleshooting

RRCConnectionReconfiguration is present but the complete message never appears.

Likely cause: The UE may have failed to apply one or more populated configuration blocks.

What to inspect: Check the preceding reconfiguration content, UE capability alignment, and whether the procedure switched into failure handling.

Next step: Use the missing completion as the boundary marker, then inspect the downlink reconfiguration in detail.

The complete message is present but later behavior is still wrong.

Likely cause: The configuration may have been accepted formally but may still lead to unexpected measurement, bearer, or mobility behavior.

What to inspect: Compare the updated behavior against the applied reconfiguration content.

Next step: Move forward into the next connected-mode messages and radio behavior.

Handover still fails after the complete message.

Likely cause: The mobility update may have been acknowledged, but the target-side continuation can still fail later.

What to inspect: Correlate the completion message with the target continuation and measurement history.

Next step: Continue into the mobility path instead of stopping at the confirmation.

LTE / 5G / Variant Comparison

Compared with RRCConnectionReconfiguration

RRCConnectionReconfiguration carries the connected-mode update. RRCConnectionReconfigurationComplete is the UE confirmation that the update was applied.

Compared with NR RRCReconfigurationComplete

LTE and NR use the same completion pattern for connected-mode updates, but the surrounding procedures and configuration containers differ between TS 36.331 and TS 38.331.

FAQ

What is RRCConnectionReconfigurationComplete in LTE?

It is the uplink LTE RRC message the UE sends to confirm successful handling of RRCConnectionReconfiguration.

What comes after RRCConnectionReconfigurationComplete?

Later connected-mode LTE RRC signaling continues using the updated configuration, or target-side continuation follows in handover-related cases.

What should I inspect first in RRCConnectionReconfigurationComplete?

Start with the transaction identifier and its correlation with the earlier reconfiguration.

Why is RRCConnectionReconfigurationComplete important?

It confirms whether the connected-mode LTE update actually completed, which is critical for mobility, bearer, and measurement troubleshooting.

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.