5G RRC Messages – Complete NR RRC Message List & Procedures
5G NR RRC, or Radio Resource Control, is the control-plane protocol between the UE and the gNB. Defined in 3GPP TS 38.331, RRC controls connection establishment, system information, security activation, radio bearer configuration, measurements, mobility, reestablishment, resume, release, sidelink, IAB, NTN, MBS, and other radio access procedures.
Use this page to search or browse 5G RRC messages by procedure category. Each message page explains where the message appears in the call flow, which side sends it, why it matters, and how engineers use it during trace analysis and troubleshooting.
Based on 3GPP TS 38.331
Start typing to search message names, slugs, categories, descriptions, and acronyms.
Broadcast & System Information Messages
Broadcast messages and system information blocks used by the UE to acquire cell access, configuration, mobility, slicing, NTN, and MBS information.
MIB
Master Information Block carrying essential cell access information.
SIB1
System Information Block 1 with initial access, scheduling, and cell selection information.
System Information
Carries scheduled system information blocks beyond MIB and SIB1.
System Information Request
Requests on-demand system information from the network.
Dedicated SIB Request
Requests dedicated delivery of selected system information.
SIB2
Cell reselection and intra-frequency related system information.
SIB3
Intra-frequency cell reselection system information.
SIB4
Inter-frequency cell reselection system information.
SIB5
Inter-RAT or neighboring frequency related system information.
SIB6
LTE inter-RAT cell reselection information.
SIB7
UTRA inter-RAT cell reselection information.
SIB8
CDMA2000 or inter-RAT system information.
SIB9
Time and system information broadcast support.
SIB10
Warning and public safety related system information.
SIB11
Additional warning or ETWS related broadcast information.
SIB12
CMAS or public warning related broadcast information.
SIB13
Advanced broadcast or service-specific system information.
SIB14
Extended system information for specialized NR features.
SIB15
Positioning or advanced system information broadcast.
SIB16
Time and positioning related system information.
SIB17
Advanced system information for release-specific features.
SIB18
Sidelink or V2X related system information.
SIB19
NTN related system information for non-terrestrial access.
SIB20
MBS broadcast related system information.
SIB21
Release-specific advanced system information.
SIB22
Release-specific advanced system information.
SIB23
Release-specific advanced system information.
SIB24
Release-specific advanced system information.
SIB25
Release-specific advanced system information.
RRC Setup Messages
Initial RRC connection establishment messages used when the UE moves from idle/inactive access toward connected-mode signalling.
RRC Setup Request
Starts initial RRC connection establishment from the UE.
RRC Setup
Configures the initial signalling radio bearer for connected-mode access.
RRC Setup Complete
Confirms setup completion and can carry the initial NAS message.
RRC Reject
Rejects initial RRC connection establishment with wait handling.
Security Messages
Messages used to activate or reject AS security mode during connected-mode setup.
NAS / Information Transfer Messages
RRC containers used to transfer NAS or dedicated information between UE and network.
DL Information Transfer
Carries downlink NAS or dedicated information to the UE.
UL Information Transfer
Carries uplink NAS or dedicated information from the UE.
DL Dedicated Message Segment
Segments large downlink dedicated RRC or NAS payloads.
UL Dedicated Message Segment
Segments large uplink dedicated RRC or NAS payloads.
Dedicated NAS Message
Dedicated NAS payload carried inside RRC information transfer messages.
Coming soonDL Information Transfer MRDC
Downlink information transfer used in MR-DC contexts.
UL Information Transfer IRAT
Uplink information transfer for inter-RAT context.
Reconfiguration & Bearers Messages
Messages used for connected-mode configuration, bearer changes, measurements, mobility configuration, and feature activation.
RRC Reconfiguration
Configures radio bearers, measurements, mobility, and feature-specific parameters.
RRC Reconfiguration Complete
Confirms successful application of RRC reconfiguration.
RRC Reconfiguration Failure
Reports failed application of RRC reconfiguration.
Coming soonCounter Check
Requests PDCP count verification for security and integrity checking.
Counter Check Response
Returns counter check information from the UE.
UE Capability Enquiry
Requests UE radio capability information.
UE Capability Information
Reports UE radio access capability information.
Logged Measurement Configuration
Configures logged measurement collection at the UE.
Logged Measurement Report
Reports logged measurement information collected by the UE.
Coming soonMeasurement Configuration
Configures measurement objects, report configs, and measurement identities.
Measurements & Mobility Messages
Measurement and mobility-control messages used for reporting radio conditions and steering UE movement.
Measurement Report
Reports serving and neighbor cell measurement results.
Measurement Report AppLayer
Reports application-layer measurement information.
Mobility From NR Command
Commands mobility from NR to another RAT or target system.
Conditional Reconfiguration
Provides conditional mobility or reconfiguration commands.
Coming soonConditional Reconfiguration Complete
Confirms completion of a conditional reconfiguration branch.
Coming soonHandover Preparation Information
Carries handover preparation information used during mobility.
Coming soonHandover Command
Commands the UE to execute mobility to the target cell.
Coming soonUE Information Request
Requests UE information such as failure or logged measurement details.
UE Information Response
Returns requested UE information to the network.
Location Measurement Indication
Indicates location measurement information.
Reestablishment Messages
Messages used when the UE attempts to recover from radio link failure or similar connected-mode failure.
RRC Reestablishment Request
Starts RRC recovery after radio link failure or similar failure.
RRC Reestablishment
Accepts and configures RRC reestablishment.
RRC Reestablishment Complete
Confirms successful RRC reestablishment.
RRC Reestablishment Reject
Rejects the RRC reestablishment attempt.
Coming soonResume Messages
Messages used to resume a suspended or inactive RRC context.
Release Messages
Messages used to release or move the UE out of active connected signalling.
Failure & Assistance Messages
Messages used by the UE or network to report radio failures, configuration problems, or assistance information.
UE Assistance Information
Reports UE assistance preferences and constraints.
Failure Information
Reports radio or configuration failure information.
MCG Failure Information
Reports master cell group failure information.
SCG Failure Information
Reports secondary cell group failure information.
SCG Failure Information NR
Reports NR secondary cell group failure information.
Coming soonSCG Failure Information EUTRA
Reports E-UTRA secondary cell group failure information.
UL Information Transfer MRDC
Carries uplink information in MR-DC failure or coordination contexts.
InDeviceCoexIndication
Reports in-device coexistence assistance information.
Coming soonOverheating Assistance
Reports UE overheating assistance information.
Coming soonIDC Assistance
Reports interference or coexistence assistance information.
Coming soonIndirect Path Failure Information
Reports indirect path failure information.
UE Positioning Assistance Info
Provides UE positioning assistance information.
Sidelink / V2X Messages
RRC messages and configurations related to NR sidelink, V2X, and PC5 operation.
Sidelink UE Information NR
Reports NR sidelink information and resource needs.
Sidelink UE Information EUTRA
Reports E-UTRA sidelink information and resource needs.
Coming soonSidelinkPreconfigNR
Preconfigured NR sidelink parameters.
Coming soonSidelinkPreconfigEUTRA
Preconfigured E-UTRA sidelink parameters.
Coming soonSL-UEInformationNR
NR sidelink UE information message.
Coming soonSL-UEInformationEUTRA
E-UTRA sidelink UE information message.
Coming soonSIB18
Sidelink or V2X related system information.
IAB Messages
Integrated Access and Backhaul RRC messages and information for IAB nodes.
IAB Other Information
Carries IAB-related information for integrated access and backhaul nodes.
IAB Other Information Request
Requests IAB other information from an IAB node.
Coming soonIAB Node Information
Reports IAB node information.
Coming soonIAB Release
Releases IAB-related RRC context or configuration.
Coming soonIAB TNL Address Request
Requests IAB transport network layer address information.
Coming soonIAB TNL Address Response
Returns IAB transport network layer address information.
Coming soonNTN Messages
Non-terrestrial network related RRC messages and system information.
NTN System Information
NTN system information carried through SIB19.
NTN Assistance Information
UE or network assistance information for NTN operation.
Coming soonSIB19
NTN related system information for non-terrestrial access.
MBS / Broadcast Messages
Multicast and broadcast service related RRC messages, including MBS broadcast acquisition and service control.
SIB20
MBS broadcast related system information.
MBS Broadcast Configuration
Configures MBS broadcast reception and service acquisition.
MBS Multicast Configuration
Configures MBS multicast reception.
MBS Interest Indication
Reports UE interest in MBS services.
MBS Session Information
Provides MBS session information.
Coming soonMCCH Message
Carries multicast control channel information.
Coming soonMTCH Configuration
Configures multicast traffic channel reception.
Coming soonMost Used RRC Messages
Common RRC Procedure Flows
RRC Setup Flow
RRC Setup Request -> RRC Setup / RRC Reject -> RRC Setup Complete
Security Activation Flow
Security Mode Command -> Security Mode Complete / Security Mode Failure
RRC Reconfiguration Flow
RRC Reconfiguration -> RRC Reconfiguration Complete / RRC Reconfiguration Failure
RRC Reestablishment Flow
RRC Reestablishment Request -> RRC Reestablishment / RRC Reestablishment Reject -> RRC Reestablishment Complete
RRC Resume Flow
RRC Resume Request -> RRC Resume -> RRC Resume Complete
System Information Flow
MIB -> SIB1 -> System Information
FAQ
What is RRC in 5G NR?
RRC, or Radio Resource Control, is the control-plane protocol between the UE and the gNB. It controls radio connection setup, security activation, configuration, mobility, measurements, system information, release, resume, and reestablishment.
Which specification defines 5G NR RRC?
5G NR RRC is defined in 3GPP TS 38.331.
What are the most important 5G RRC messages?
The most commonly analyzed 5G RRC messages include MIB, SIB1, RRC Setup Request, RRC Setup, RRC Setup Complete, RRC Reconfiguration, Measurement Report, RRC Reestablishment Request, RRC Resume Request, and RRC Release.
What is the difference between RRC Setup and RRC Reconfiguration?
RRC Setup establishes initial connected-mode signalling, mainly SRB1. RRC Reconfiguration is used later to modify radio bearers, measurements, mobility, and feature-specific configuration.
What is the difference between RRC Release and RRC Resume?
RRC Release moves the UE out of active connected-mode signalling. RRC Resume is used when a UE resumes a previously suspended or inactive context.
What are SIB messages in 5G?
SIB messages are System Information Blocks broadcast by the cell to provide access, mobility, slicing, positioning, NTN, MBS, and other system-level information to UEs.
References
- 3GPP TS 38.331 – NR; Radio Resource Control (RRC); Protocol specification
- 3GPP TS 38.300 – NR and NG-RAN overall description
- 3GPP TS 38.304 – NR UE procedures in idle and inactive states