| Protocol | rrc | Network | 5g |
|---|---|---|---|
| Spec | 3GPP TS 38.331 | Spec Section | 6.2.2 |
| Direction | UE -> gNB | Message Type | MBS Control |
| Full message name | 5G NR - MBS Interest Indication |
|---|---|
| Protocol | RRC |
| Technology | 5G |
| Direction | UE -> gNB |
| Interface | Uu |
| Signaling bearer / channel | SRB1 / UL-DCCH |
| Typical trigger | Used when the UE needs to indicate its interest in MBS service reception. |
| Main purpose | Lets the UE signal its MBS reception interest so the network can make the right service, configuration, or continuity decisions. |
| Main specification | 3GPP TS 38.331, 6.2.2 |
| Release added | Release 17 |
| Procedures where used | MBS Service Interest Signaling |
MBS Interest Indication is the UE-to-network NR RRC message used to indicate interest in MBS services or sessions.
Lets the UE signal its MBS reception interest so the network can make the right service, configuration, or continuity decisions.
MBS Interest Indication tells the network which MBS service the UE is interested in.
Call flow position: Sent when the UE indicates MBS service interest to the network.
Typical state: UE is in connected mode with MBS-related context.
Preconditions:
Next likely message: Network configuration or service handling update
Previous message(s): MBS Broadcast Configuration, MBS Multicast Configuration
Next message(s): MBS configuration update, MBS continuity handling
Security context: Sent as protected connected-mode signaling.
MBSInterestIndication ::= SEQUENCE {
mbsInterestInfo OCTET STRING
}
Engineers usually correlate the message with later MBS configuration or continuity behavior.
UL-DCCH-Message
message: mbsInterestIndication
mbsInterestInfo: present
| IE | Required | Description |
|---|---|---|
mbsInterestInfo | Yes | Carries the UE's MBS interest indication information. |
mbsInterestInfoCarries the UE's MBS interest indication information.
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.
Likely cause: The UE may not have sent the expected interest indication.
What to inspect: Check the content and timing of MBS Interest Indication.
Next step: Compare it with later network-side MBS configuration messages.
It lets the UE tell the network which MBS service or session it is interested in.
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.