| Protocol | rrc | Network | 5g |
|---|---|---|---|
| Spec | 3GPP TS 38.331 | Spec Section | 6.2.2 |
| Direction | gNB -> UE | Message Type | Segmented Dedicated Control |
| Full message name | 5G NR - DL Dedicated Message Segment |
|---|---|
| Protocol | RRC |
| Technology | 5G |
| Direction | gNB -> UE |
| Interface | Uu |
| Signaling bearer / channel | SRB1 / SRB2 / DL-DCCH |
| Typical trigger | Used when a downlink dedicated RRC payload exceeds the practical size of a single message unit. |
| Main purpose | Lets the network split large dedicated RRC content across multiple downlink segments while keeping the UE aware of sequence and completion. |
| Main specification | 3GPP TS 38.331, 6.2.2 |
| Release added | Release 16 |
| Procedures where used | Large Dedicated RRC Delivery, Segmented RRC Reconfiguration Delivery |
DL Dedicated Message Segment is the NR downlink RRC segmentation container used when a dedicated RRC message is too large to send as a single unit.
Lets the network split large dedicated RRC content across multiple downlink segments while keeping the UE aware of sequence and completion.
DL Dedicated Message Segment is just a way to split a large downlink RRC message into smaller pieces.
Call flow position: Used during delivery of a large dedicated RRC payload that must be segmented.
Typical state: UE is in RRC_CONNECTED.
Preconditions:
Next likely message: Next segment or reassembled final message
Previous message(s): RRC Reconfiguration
Next message(s): Later DL dedicated message segments, Segment reassembly at the UE
Security context: Sent as protected connected-mode signaling.
DLDedicatedMessageSegment ::= SEQUENCE {
segmentNumber INTEGER,
segmentContainer OCTET STRING
}
Segment numbers and the presence of all expected fragments matter more than the outer wrapper itself.
DL-DCCH-Message
message: dlDedicatedMessageSegment
segmentNumber: 1
segmentContainer: present
| IE | Required | Description |
|---|---|---|
segmentNumber | Yes | Identifies the current segment sequence. |
segmentContainer | Yes | Carries the dedicated RRC payload fragment. |
segmentNumberIdentifies the current segment sequence.
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.
segmentContainerCarries the dedicated RRC payload fragment.
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: One or more segments may be missing or reassembly may have failed.
What to inspect: Check segment numbering and whether the final segment arrived.
Next step: Correlate segmentation with any later reject, failure, or missing completion.
The downlink version carries large network-to-UE dedicated messages, while the uplink version carries large UE-to-network dedicated messages.
It is used when a dedicated downlink RRC message is too large to send as one piece.
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.