Content for TS 23.180 Word version: 18.0.0
10.5 MCPTT service
10.5.1 IOPS group call (IP connectivity functionality)
10.5.1.1 General
10.5.1.2 Information flows
10.5.1.3 IOPS group call setup
10.5.1.4 IOPS emergency group call
10.5.1.5 IOPS group call release
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10.5 MCPTT service p. 31
10.5.1 IOPS group call (IP connectivity functionality) p. 31
10.5.1.1 General p. 31
The support of MCPTT group calls based on the IP connectivity functionality in the IOPS mode of operation enables that the service is provided by the MCPTT clients over the IOPS MC connectivity function. The IOPS MC connectivity function provides IP connectivity for the communication among MCPTT users.
IOPS group calls based on the IP connectivity functionality can use pre-configured information provided to MCPTT clients prior to the IOPS group call. Therefore, when a MCPTT client initiates an IOPS group call it uses the pre-configured IOPS group IP multicast address associated to the target IOPS MCPTT group ID to establish the IOPS group call based on the IP connectivity functionality. The related packets, i.e. signalling and media, of the IOPS group call are transmitted to the IOPS MC connectivity function for distribution to the corresponding discovered MC users of the target IOPS MCPTT group.
The IOPS MC connectivity function can distribute the group session packets to the discovered MC users over MBMS bearers as described in clause 10.4.5.
The IOPS MC connectivity function can also replicate and distribute the group session packets over unicast transmissions to MCPTT UEs associated to the target IOPS MCPTT group. MCPTT UEs receiving the group session packets are associated to discovered MC users that included the target IOPS MCPTT group ID in the IOPS discovery request, as described in clause 10.5.2.3.
The following clauses specify the IOPS group call procedures and information flows for the IP connectivity functionality in the IOPS mode of operation.
10.5.1.2 Information flows p. 31
10.5.1.2.1 IOPS group call announcement p. 31
Table 10.5.1.2.1-1 describes the information flow for the IOPS group call announcement from one MCPTT client to other MCPTT clients. The packet(s) carrying the IOPS group call announcement are transmitted from the originating MCPTT client to the IOPS MC connectivity function for distribution to the target MCPTT clients.
| Information Element | Status | Description |
|---|---|---|
| IOPS MCPTT ID | M | The identity of the calling party |
| IOPS MCPTT group ID | M | The IOPS MCPTT group ID on which the call is to be conducted |
| SDP offer | M | Media parameters of the MCPTT client |
| Announcement period | M | Period of the group call announcement |
| Encryption parameters | O | Encryption parameters to be used for the call, if the call is to be encrypted |
| Confirm mode indicator | O | Indicates whether the MCPTT group call is to be confirmed |
| Emergency indicator | O | Indicates that the MCPTT group call is an MCPTT emergency call |
10.5.1.2.2 IOPS group call response p. 31
Table 10.5.1.2.2-1 describes the information flow for the IOPS group call response from one MCPTT client to other MCPTT clients. The packet(s) carrying the IOPS group call response is transmitted from the called MCPTT client to the IOPS MC connectivity function for distribution to the target MCPTT clients.
| Information Element | Status | Description |
|---|---|---|
| IOPS MCPTT ID | M | The identity of the called party |
| IOPS MCPTT group ID | M | The IOPS MCPTT group ID of the group on which the call is requested |
| SDP answer | M | Media parameters selected |
| Result | M | Result of the group call announcement (success or failure) |
10.5.1.2.3 IOPS emergency group call upgrade p. 32
Table 10.5.1.2.3-1 describes the information flow for the IOPS emergency group call upgrade from one MCPTT client to other MCPTT clients. The packet(s) carrying the IOPS emergency group call upgrade are transmitted from the originating MCPTT client to the IOPS MC connectivity function for distribution to the target MCPTT clients.
| Information Element | Status | Description |
|---|---|---|
| IOPS MCPTT ID | M | The identity of the upgrading MC user |
| IOPS MCPTT group ID | M | The IOPS MCPTT group ID on which the call is to be upgraded to emergency call |
10.5.1.2.4 IOPS emergency group call state cancel p. 32
Table 10.5.1.2.4-1 describes the information flow for the IOPS emergency group call state cancel from one MCPTT client to other MCPTT clients. The packet(s) carrying the IOPS emergency group call state cancel are transmitted from the originating MCPTT client to the IOPS MC connectivity function for distribution to the target MCPTT clients.
| Information Element | Status | Description |
|---|---|---|
| IOPS MCPTT ID | M | The identity of the cancelling MC user |
| IOPS MCPTT group ID | M | The IOPS MCPTT group ID on which the emergency call state is to be cancelled |
10.5.1.3 IOPS group call setup p. 32
The procedure in Figure 10.5.1.3-1 illustrates the procedure for an IOPS MCPTT group call establishment based on the IP connectivity functionality. The procedure describes how an MCPTT client initiates and establishes an IOPS MCPTT group call with other MCPTT clients.
Pre-conditions:
- MCPTT user profile used for the IOPS mode of operation is pre-provisioned in the MCPTT UEs;
- The IOPS MCPTT group ID and its associated IOPS group IP multicast address are pre-configured in the MCPTT clients;
- MCPTT users have an active PDN connection to the IOPS MC connectivity function for the communication based on the IP connectivity functionality;
- MCPTT users affiliated to the target IOPS MCPTT group are discovered by the IOPS MC connectivity function supporting the IP connectivity functionality;
- The IOPC MC connectivity function may have established an MBMS bearer and announced it to the MCPTT clients;
- MCPTT client 1 may have retrieved group connectivity information from the IOPS connectivity client related to the target IOPS MCPTT group;
- MCPTT clients 1, 2 … n are configured within the same IOPS MCPTT group.
Figure 10.5.1.3-1: IOPS group call setup based on the IP connectivity functionality
(⇒ copy of original 3GPP image)
(⇒ copy of original 3GPP image)
Step 1.
The MCPTT user at MCPTT client 1 would like to initiate an IOPS group call with a specific IOPS MCPTT group based on the IP connectivity functionality.
Step 2.
The MCPTT client 1 sends an IOPS group call announcement to the target IOPS MCPTT group. The MCPTT client 1 transmits the group session packets carrying the IOPS group call announcement to the IOPS MC connectivity function for distribution to the corresponding IOPS group IP multicast address.
Step 3.
The IOPS MC connectivity function determines that the received packets correspond to a group session targeting a specific IOPS MCPTT group. The IOPS MC connectivity function decides distributing the received group session packets to the target MCPTT clients over MBMS and/or unicast transmissions.
Step 4.
The IOPS MC connectivity function distributes the group session packets carrying the IOPS group call announcement to the MCPTT clients from the target IOPS MCPTT group.
Step 5.
The MCPTT clients receiving the IOPS group call announcement join the IOPS group call and notify the target MCPTT users about the IOPS group call.
Step 6.
If confirm mode indication is included in the IOPS group call announcement, the receiving MCPTT clients respond to the IOPS MCPTT group indicating the result of the establishment of the announced IOPS group call. The receiving MCPTT clients transmit the group session packets carrying the IOPS group call response to the IOPS MC connectivity function for distribution to the corresponding IOPS group IP multicast address.
Step 7.
The IOPS MC connectivity function determines that the received packets correspond to a group session targeting a specific IOPS MCPTT group. The IOPS MC connectivity function decides distributing the received group session packets to the target MCPTT clients over MBMS and/or unicast transmissions.
Step 8.
The IOPS MC connectivity function distributes the group session packets carrying the IOPS group call response to the MCPTT clients from the target IOPS MCPTT group. The MCPTT clients recognize the IOPS group call originator through the IOPS group call announcement and can check the participants of the IOPS group call through the received response message.
Step 9.
The MCPTT clients have successfully established the IOPS group call with floor control based on the IP connectivity functionality.
10.5.1.4 IOPS emergency group call p. 34
The procedure in Figure 10.5.1.4-1 illustrates the procedure for an IOPS MCPTT emergency group call establishment based on the IP connectivity functionality. The IOPS emergency group call is a special case of the IOPS group call setup procedure described in clause 10.5.1.3, wherein the IOPS group call announcement contains an indication that the IOPS group call is an IOPS emergency group call. The group call participants can become aware of the IOPS MCPTT group's in-progress emergency state based on the emergency indicator.
When an MCPTT client intends to initiate an IOPS emergency group call, the MCPTT client can request higher priority from the IOPS MC connectivity function via the IOPS discovery request.
An IOPS group call in-progress can be upgraded to an IOPS emergency group call by including the emergency indicator within the periodic IOPS group call announcement. An IOPS group call in-progress can also be upgraded by a participating MCPTT client by sending an IOPS emergency group call upgrade to the IOPS group.
The MCPTT user who initiated an IOPS emergency group call, or upgraded an IOPS group call to an emergency group call, or an authorized user can cancel the emergency state of the group call by sending an IOPS emergency group call state cancel to the IOPS MCPTT group. The emergency state of the IOPS group call remains active until the emergency group call ends or the in-progress emergency state is cancelled.
Pre-conditions:
- MCPTT user profile used for the IOPS mode of operation is pre-provisioned in the MCPTT UEs;
- The IOPS MCPTT group ID and its associated IOPS group IP multicast address are pre-configured in the MCPTT clients;
- MCPTT users have an active PDN connection to the IOPS MC connectivity function for the communication based on the IP connectivity functionality;
- MCPTT users affiliated to the target IOPS MCPTT group are discovered by the IOPS MC connectivity function supporting the IP connectivity functionality;
- The IOPC MC connectivity function may have established an MBMS bearer and announced it to the MCPTT clients;
- MCPTT client 1 may have retrieved group connectivity information from the IOPS connectivity client related to the target IOPS MCPTT group;
- MCPTT clients 1, 2 … n are configured within the same IOPS MCPTT group.
Figure 10.5.1.4-1: IOPS emergency group call setup based on the IP connectivity functionality
(⇒ copy of original 3GPP image)
(⇒ copy of original 3GPP image)
Step 1.
The MCPTT user at MCPTT client 1 would like to initiate an IOPS emergency group call with a specific IOPS MCPTT group based on the IP connectivity functionality.
Step 2.
The MCPTT client 1 sends an IOPS group call announcement to the target IOPS MCPTT group. The announcement contains an indication that the call is an IOPS emergency group call. The MCPTT client 1 transmits the group session packets carrying the IOPS group call announcement to the IOPS MC connectivity function for distribution to the corresponding IOPS group IP multicast address.
Step 3.
The IOPS MC connectivity function determines that the received packets correspond to a group session targeting a specific IOPS MCPTT group. The IOPS MC connectivity function decides to distribute the received group session packets to the target MCPTT clients over MBMS and/or unicast transmissions. If the MCPTT client 1 requested a priority state from the IOPS MC connectivity function, the IOPS MC connectivity function distributes the group session packets with higher priority.
Step 4.
The IOPS MC connectivity function distributes the group session packets carrying the IOPS group call announcement to the MCPTT clients from the target IOPS MCPTT group.
Step 5.
The MCPTT clients receiving the IOPS group call announcement with an emergency indicator join the IOPS emergency group call and notify the target MCPTT users about the IOPS emergency group call. The IOPS MCPTT group's emergency state is defined.
Step 6.
If confirm mode indication is included in the IOPS group call announcement, the receiving MCPTT clients respond to the IOPS MCPTT group indicating the result of the establishment of the announced IOPS emergency group call. The receiving MCPTT clients transmit the group session packets carrying the IOPS group call response to the IOPS MC connectivity function for distribution to the corresponding IOPS group IP multicast address.
Step 7.
The IOPS MC connectivity function determines that the received packets correspond to a group session targeting a specific IOPS MCPTT group. The IOPS MC connectivity function decides to distribute the received group session packets to the target MCPTT clients over MBMS and/or unicast transmissions. If any participating MCPTT client of the group call requested a priority state from the IOPS MC connectivity function, the IOPS MC connectivity function distributes the group session packets with higher priority.
Step 8.
The IOPS MC connectivity function distributes the group session packets carrying the IOPS group call response to the MCPTT clients from the target IOPS MCPTT group. The MCPTT clients recognize the IOPS emergency group call originator through the IOPS group call announcement and can check the participants of the IOPS group call through the received response message.
Step 9.
The MCPTT clients have successfully established the IOPS emergency group call based on the IP connectivity functionality.
10.5.1.5 IOPS group call release p. 36
Each MCPTT client may release itself from an ongoing IOPS group call without the transmission of any signalling if the call has been inactive for a specific duration.
