10.6.5 Emergency alert cancellation

23.2833GPPMission Critical Communication Interworking with Land Mobile Radio SystemsRelease 18TS

10.6.5.1 Emergency alert cancellation of an LMR user

In this procedure, an LMR user is cancelling the emergency alert. Figure 10.6.5.1-1 shows the procedure for emergency alert cancellation of a user in the LMR system. This subclause is based upon subclause for MCPTT emergency alert cancel in 3GPP TS 23.379 [7], subclause 10.6.2.6.3.2.

Pre-conditions:

1. The MC service group information is available at the IWF, including information that the MC service group is an interworking group (defined in the LMR system or the MC system).

2. The LMR user had previously successfully initiated an emergency alert via the IWF.

3. The MC service client 1 and MC service client 2 are affiliated to the MC service group.

4. The MC service server may have carried out an explicit or implicit affiliation procedure of the LMR user to the MC service group.

5. The mapping relationship of group and user identities between the MC system and the LMR system has been configured at the IWF.

6. The LMR user initiates an emergency alert cancel.

NOTE 1: For all the signalling messages passing through the IWF between the MC system and the LMR system, the IWF performs the identity conversion and protocol translation.

Figure 10.6.5.1-1 MC service emergency alert cancellation of an LMR user

1. The IWF sends an IWF emergency alert cancel request to the MC service group to which the IWF had previously successfully sent the IWF emergency alert request on behalf of the LMR user.

NOTE 2: The IWF emergency alert cancel request may carry an indication to also request that the in-progress emergency state on the group is to be cancelled.

2. The MC service server sends the IWF emergency alert cancel response to the IWF to confirm the IWF emergency alert cancellation.

3. The MC service server sends an MC service emergency alert cancel request to the MC service clients of the affiliated MC service group members.

4. MC service users are notified of the MC service emergency alert cancellation of the LMR user.

5. The receiving MC service clients send the MC service emergency alert cancel response to the MC service server to acknowledge the MC service emergency alert cancel request. For a multicast call scenario, these acknowledgements are not sent.

NOTE 3: Steps 2 and 3 can be performed in which ever order.

10.6.5.2 Emergency alert cancellation of an MC service user

In this procedure, an MC service user is cancelling the emergency alert. Figure 10.6.5.2-1 shows the procedure for emergency alert cancellation from a user in the MC system. This subclause is based upon subclause for MCPTT emergency alerts in 3GPP TS 23.379 [7], subclause 10.6.2.6.3.2.

Pre-conditions:

1. The MC service group information is available at the IWF, including information that the MC service group is an interworking group (defined in the LMR system or the MC system).

2. The MC service client 1 had previously successfully initiated an MC service emergency alert request.

3. The MC service client 1 is still in the emergency state.

4. The MC service client 2 is affiliated to the MC service group.

5. The MC service server may have carried out an explicit or implicit affiliation procedure of the LMR user with the MC service group.

6. The mapping relationship of group and user identities between the MC system and the LMR system has been configured at the IWF.

NOTE 1: For all the signalling messages passing through the IWF between the MC system and the LMR system, the IWF performs the identity conversion and protocol translation.

Figure 10.6.5.2-1 MC service emergency alert cancellation of an MC service user

1. The user at the MC service client 1 initiates an emergency alert cancel.

NOTE 2: The MC service emergency alert cancel request may carry an indication that the in-progress emergency state on the group is to be cancelled.

2. MC service client 1 requests the MC service server to send an MC service emergency alert cancel to the MC service group to which MC service client 1 had previously sent the emergency alert request. The MC service server resolves the group ID, determines the affiliation status of the group members and checks whether the IWF should be informed. In this scenario, the group has affiliated members that are homed on the IWF, thus the IWF shall be involved.

3. The MC service server sends the MC service emergency alert cancel response to the MC service client 1 to confirm the MC service emergency alert cancel request. MC service client 1 resets its emergency state.

4. The MC service server sends an IWF emergency alert cancel request(s) to the IWF. If the IWF has affiliated to this group on behalf of the group’s LMR users, only one IWF emergency alert cancel request message is sent to the IWF. If the MCPTT server has received individual affiliations from the group’s LMR users, an individual IWF emergency alert cancel request message is sent to the IWF for each affiliated LMR user.

5. The IWF sends an IWF emergency alert cancel response(s) to the MC service server to acknowledge the IWF emergency alert cancel request(s).

6. The MC service server sends an MC service emergency alert cancel request towards the MC service clients of the affiliated MC service group members.

7. MC service users are notified of the MC service emergency alert cancellation of MC service client 1.

8. The receiving MC service clients send the MC service emergency alert cancel response to the MC service server to acknowledge the MC service emergency alert cancel request. For a multicast call scenario, these acknowledgements are not sent.

NOTE 3: Steps 3 and 4 can be performed in which ever order.