8.12 Warning Message Transmission Procedures

36.4133GPPEvolved Universal Terrestrial Radio Access Network (E-UTRAN)Release 17S1 Application Protocol (S1AP)TS

8.12.1 Write-Replace Warning

8.12.1.1 General

The purpose of Write-Replace Warning procedure is to start or overwrite the broadcasting of warning messages.

The procedure uses non UE-associated signalling.

8.12.1.2 Successful Operation

Figure 8.12.1.2-1: Write-Replace Warning procedure. Successful operation.

The MME initiates the procedure by sending a WRITE-REPLACE WARNING REQUEST message to the eNB.

Upon receipt of the WRITE-REPLACE WARNING REQUEST, eNB shall prioritise its resources to process the warning message.

If, in a certain area, broadcast of a warning message is already ongoing and the eNB receives a WRITE-REPLACE WARNING REQUEST message with Message Identifier IE and/or Serial Number IE which are different from those in the warning message being broadcast, and if the Concurrent Warning Message Indicator IE is not present, the eNB shall replace the warning message being broadcast with the newly received one for that area.

If the eNB receives a WRITE-REPLACE WARNING REQUEST message with a warning message identified by the Message Identifier IE and Serial Number IE and if there are no prior warning messages being broadcast in any of warning areas indicated in the Warning Area List IE, the eNB shall broadcast the received warning message for those area(s).

If, in a certain area, broadcast of one or more warning messages are already ongoing and the eNB receives a WRITE-REPLACE WARNING REQUEST message with a Message Identifier IE and/or Serial Number IE which are different from those in any of the warning messages being broadcast, and if the Concurrent Warning Message Indictor IE is present, the eNB shall schedule the received warning message for broadcast, for that area.

If the Concurrent Warning Message Indicator IE is present and if a value “0” is received in the Number of Broadcast Requested IE, the eNB shall broadcast the received warning message indefinitely until requested otherwise to stop broadcasting, except if the Repetition Period IE is set to “0”.

If, in a certain area, broadcast of one or more warning messages are already ongoing and the eNB receives a WRITE-REPLACE WARNING REQUEST message with Message Identifier IE and Serial Number IE which correspond to one of the warning messages already being broadcast in that area, the eNB shall not start a new broadcast or replace an existing one but it shall still reply by sending a WRITE-REPLACE WARNING RESPONSE message which includes the Broadcast Completed Area List IE set according to the ongoing broadcast.

If Warning Area List IE is not included in the WRITE-REPLACE WARNING REQUEST message, the eNB shall broadcast the indicated message in all of the cells within the eNB.

If Warning Type IE is included in WRITE-REPLACE WARNING REQUEST message, the eNB shall broadcast the Primary Notification irrespective of the setting of the Repetition Period IE and the Number of Broadcasts Requested IE, and process the Primary Notification according to TS 36.331 [16].

If the Warning Security Information IE is included in the WRITE-REPLACE WARNING REQUEST message, the eNB shall include this information together with the warning type in the Primary Notification.

If the Data Coding Scheme IE and the Warning Message Contents IE are both included in the WRITE-REPLACE WARNING REQUEST message, the eNB shall schedule a broadcast of the warning message according to the value of the Repetition Period IE and Number of Broadcasts Requested IE and process the warning message according to TS 36.331 [16].

If the Warning Area Coordinates IE is included in the WRITE-REPLACE WARNING REQUEST message, the eNB shall include this information together with the warning message being broadcast according to TS 36.331 [16].

The eNB acknowledges the WRITE-REPLACE WARNING REQUEST message by sending a WRITE-REPLACE WARNING RESPONSE message to the MME.

If the Broadcast Completed Area List IE is not included in the WRITE-REPLACE WARNING RESPONSE message, the MME shall consider that the broadcast is unsuccessful in all the cells within the eNB.

If the Extended Repetition Period IE is included in the WRITE-REPLACE WARNING REQUEST message, the eNB shall ignore the value in the Repetition Period IE.

8.12.1.3 Abnormal Conditions

If the Concurrent Warning Message Indicator IE is not present and if a value “0” is received in the Number of Broadcast Requested IE, the eNB shall not broadcast the received secondary notification.

If Concurrent Warning Message Indicator IE is included and if a value “0” is received in the Repetition Period IE, the eNB shall not broadcast the received warning message except if the Number of Broadcast Requested IE is set to “1”.

If Concurrent Warning Message Indicator IE is not included and if a value “0” is received in the Repetition Period IE, the eNB shall not broadcast the received secondary notification except if the Number of Broadcast Requested IE is set to “1”.

8.12.2 Kill

8.12.2.1 General

The purpose of Kill procedure is to cancel an already ongoing broadcast of a warning message.

The procedure uses non UE-associated signalling.

8.12.2.2 Successful Operation

Figure 8.12.2.2-1: Kill procedure. Successful operation.

The MME initiates the procedure by sending a KILL REQUEST message to the eNB.

If the eNB receives a KILL REQUEST message and broadcast of the warning message identified by the Message Identifier and Serial Number IE is ongoing in an area indicated within the Warning Area List IE, the eNB shall stop broadcasting the warning message within that area and discard the warning message for that area.

If the Warning Area List IE is not included in the KILL REQUEST message, the eNB shall stop broadcasting and discard the warning message identified by the Message Identifier IE and the Serial Number IE in all of the cells in the eNB.

The eNB shall acknowledge the KILL REQUEST message by sending the KILL RESPONSE message, with the Message Identifier IE and the Serial Number IE copied from the KILL REQUEST message and shall, if there is an area to report where an ongoing broadcast was stopped successfully, include the Broadcast Cancelled Area List IE.

If an area included in the Warning Area List IE in the KILL REQUEST message does not appear in the Broadcast Cancelled Area List IE, the MME shall consider that the eNB had no ongoing broadcast to stop for the same Message Identifier and Serial Number in that area.

If the Broadcast Cancelled Area List IE is not included in the KILL RESPONSE message, the MME shall consider that the eNB had no ongoing broadcast to stop for the same Message Identifier and Serial Number.

If the Kill-all Warning Messages Indicator IE is present in the KILL REQUEST message, then the eNB shall stop broadcasting and discard all warning messages for the area as indicated in the Warning Area List IE or in all the cells of the eNB if the Warning Area List IE is not included. The eNB shall acknowledge the KILL REQUEST message by sending the KILL RESPONSE message, with the Message Identifier IE and the Serial Number IE copied from the KILL REQUEST message and shall, if there is area to report where an ongoing broadcast was stopped successfully, include the Broadcast Cancelled Area List IE with the Number of Broadcasts IE set to 0.

8.12.3 PWS Restart Indication

8.12.3.1 General

The purpose of PWS Restart Indication procedure is to inform the MME that PWS information for some or all cells of the eNB are available for reloading from the CBC if needed. The procedure uses non UE-associated signalling.

8.12.3.2 Successful Operation

Figure 8.12.3.2-1: PWS Restart Indication procedure. Successful operation.

The eNB initiates the procedure by sending a PWS RESTART INDICATION message to the MME. On receipt of a PWS RESTART INDICATION message, the MME shall act as defined in TS 23.007 [38].

If the Emergency Area ID is available, the eNB shall also include it in the Emergency Area ID List for Restart IE.

8.12.4 PWS Failure Indication

8.12.4.1 General

The purpose of PWS Failure Indication procedure is to inform the MME that ongoing PWS operation for one or more cells of the eNB has failed. The procedure uses non UE-associated signalling.

8.12.4.2 Successful Operation

Figure 8.12.4.2-1: PWS Failure Indication procedure. Successful operation.

The eNB initiates the procedure by sending a PWS FAILURE INDICATION message to the MME. On receipt of a PWS FAILURE INDICATION message, the MME shall act as defined in TS 23.041 [29].