What is Write Replace Warning Request in simple terms?
Write Replace Warning Request is the NGAP warning message sent by the AMF to the NG-RAN node to start or replace public warning broadcast content such as ETWS or CMAS alerts.
Requests NG-RAN to broadcast warning content, replaces an existing warning message when matching identifiers are used, carries warning identification and broadcast-area information, carries warning content or delivery parameters, and allows NG-RAN to report handling result through Write Replace Warning Response.
Why this message matters
Write Replace Warning Request is the AMF telling the gNB to start or replace a public warning broadcast. The most important fields identify the warning, target the area, and control repetition.
ASN.1 for 5G NGAP - Write Replace Warning Request
WriteReplaceWarningRequest ::= SEQUENCE {
protocolIEs ProtocolIE-Container { {WriteReplaceWarningRequest-IEs} },
...
}
WriteReplaceWarningRequest-IEs NGAP-PROTOCOL-IES ::= {
{ ID id-MessageIdentifier CRITICALITY reject TYPE MessageIdentifier PRESENCE mandatory } |
{ ID id-SerialNumber CRITICALITY reject TYPE SerialNumber PRESENCE mandatory } |
{ ID id-WarningAreaList CRITICALITY ignore TYPE WarningAreaList PRESENCE optional } |
{ ID id-RepetitionPeriod CRITICALITY reject TYPE RepetitionPeriod PRESENCE mandatory } |
{ ID id-NumberOfBroadcastsRequested CRITICALITY reject TYPE NumberOfBroadcastsRequested PRESENCE mandatory } |
{ ID id-WarningType CRITICALITY ignore TYPE WarningType PRESENCE optional } |
{ ID id-WarningSecurityInformation CRITICALITY ignore TYPE WarningSecurityInformation PRESENCE optional } |
{ ID id-DataCodingScheme CRITICALITY ignore TYPE DataCodingScheme PRESENCE optional } |
{ ID id-WarningMessageContents CRITICALITY ignore TYPE WarningMessageContents PRESENCE optional } |
{ ID id-ConcurrentWarningMessageInd CRITICALITY ignore TYPE ConcurrentWarningMessageInd PRESENCE optional } |
{ ID id-ExtendedRepetitionPeriod CRITICALITY ignore TYPE ExtendedRepetitionPeriod PRESENCE optional } |
{ ID id-WarningAreaCoordinates CRITICALITY ignore TYPE WarningAreaCoordinates PRESENCE optional } |
{ ID id-SendWriteReplaceWarningIndication CRITICALITY ignore TYPE SendWriteReplaceWarningIndication PRESENCE optional } |
{ ID id-GlobalRANNodeID CRITICALITY ignore TYPE GlobalRANNodeID PRESENCE optional },
...
}
How to read this ASN.1
Decode Message Identifier and Serial Number first, then inspect the target area, repetition controls, content fields, and any security or concurrent-warning indicators. The paired response reports handling result.
Detailed field explanation
Message Type
Identifies the NGAP PDU as WRITE-REPLACE WARNING REQUEST.
Presence: Mandatory
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.
Message Identifier
Mandatory warning message type or category identifier.
Presence: Mandatory
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.
Serial Number
Mandatory warning message instance identifier used for replacement, update, or repeated warning handling.
Presence: Mandatory
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.
Warning Area List
Optional target area where the warning should be broadcast.
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.
Repetition Period
Mandatory timing control for warning broadcast repetition.
Presence: Mandatory
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.
Number of Broadcasts Requested
Mandatory count of requested warning broadcast repetitions.
Presence: Mandatory
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.
Warning Type
Optional ETWS warning type information.
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.
Warning Security Information
Optional security information for warning delivery.
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.
Data Coding Scheme
Optional coding scheme for warning message contents.
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.
Warning Message Contents
Optional warning text or payload to be broadcast.
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.
Concurrent Warning Message Indication
Optional indicator for concurrent warning-message handling.
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.
Extended Repetition Period
Optional extended timing control for longer repetition periods.
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.
Warning Area Coordinates
Optional geographical area information for warning targeting.
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.
Send Write Replace Warning Indication
Optional request for additional indication behavior.
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.
Global RAN Node ID
Optional RAN node identity context.
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.
