What is UL Information Transfer IRAT r16 in LTE?
It is the uplink LTE RRC message the UE uses to transfer dedicated information associated with inter-RAT handling.
| Protocol | lte-rrc | Network | lte |
|---|---|---|---|
| Spec | 3GPP TS 36.331 | Spec Section | 5.6, 6.2.2 |
| Direction | UE -> eNodeB | Message Type | Dedicated Transfer / IRAT |
| Full message name | LTE RRC UL Information Transfer IRAT r16 |
|---|---|
| Protocol | LTE-RRC |
| Technology | LTE |
| Direction | UE -> eNodeB |
| Interface | Uu |
| Signaling bearer / channel | SRB1 / UL-DCCH |
| Typical trigger | Triggered when the UE needs to deliver dedicated information associated with an inter-RAT branch. |
| Main purpose | Carries UE-originated dedicated information for inter-RAT handling so the network can continue the IRAT branch correctly. |
| Main specification | 3GPP TS 36.331, 5.6, 6.2.2 |
| Release added | Release 16 |
| Procedures where used | Inter-RAT dedicated information transfer |
Uplink LTE RRC message used to transfer dedicated information in inter-RAT related contexts.
Carries UE-originated dedicated information for inter-RAT handling so the network can continue the IRAT branch correctly.
UL Information Transfer IRAT r16 is the LTE UE message used to carry dedicated inter-RAT information to the network.
Call flow position: UE message carrying dedicated information during an inter-RAT branch.
Typical state: The message transports information needed for IRAT handling rather than commanding the mobility step itself.
Preconditions:
Next likely message: Later IRAT handling or mobility continuation
Call flow position: Uplink transfer step used when the UE needs to send inter-RAT specific dedicated content.
Typical state: The message is best read as a wrapper for the dedicated inter-RAT payload.
Preconditions:
Next likely message: Forwarding, processing, or later inter-RAT continuation
Previous message(s): RRCConnectionReconfiguration, Inter-RAT preparation
Next message(s): Network-side IRAT handling
Security context: Sent as protected connected-mode signaling.
ULInformationTransferIRAT-r16 ::= SEQUENCE {
criticalExtensions CHOICE {
c1 CHOICE {
ulInformationTransferIRAT-r16 ULInformationTransferIRAT-r16-IEs,
spare3 NULL,
spare2 NULL,
spare1 NULL
},
criticalExtensionsFuture SEQUENCE {}
}
}
Read the message through the dedicated inter-RAT container it carries and the branch around it.
UL-DCCH-Message
message c1 : ulInformationTransferIRAT-r16 : {
criticalExtensions c1 : ulInformationTransferIRAT-r16 : {
dedicatedInfoType-r16 present
}
}
| IE | Required | Description |
|---|---|---|
dedicatedInfoType-r16 | Yes | Carries the inter-RAT related dedicated payload type. |
dedicatedInfoType-r16Carries the inter-RAT related dedicated payload type.
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 uplink inter-RAT information transfer may be missing, delayed, or carrying unexpected content.
What to inspect: Check whether UL Information Transfer IRAT r16 appears and what payload it carries.
Next step: Treat the issue as dedicated payload transport or interpretation before assuming the mobility command itself failed.
It is the uplink LTE RRC message the UE uses to transfer dedicated information associated with inter-RAT handling.
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.