9.12 Dynamic group management

23.2863GPPApplication layer support for Vehicle-to-Everything (V2X) servicesFunctional architecture and information flowsRelease 18TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

9.12.1 General

Some of the V2X scenarios require group-based communication (e.g. platooning). Unlike V2X communication for safety scenarios where all V2X UEs in the communication range receive broadcasted communication, the group-based communication is expected to be received only by the V2X UEs of the members of that group. However in some scenarios the V2X UEs are required to be determined dynamically (with the assistance of the V2X application server or independently by the V2X UEs when they are not connected to the network) during the operation. Also each V2X application group has to be mapped to a ProSe Layer-2 group ID in order to avoid any interference during PC5 communications for the V2X application groups. The ProSe Layer-2 Group ID is only used in PC5 V2X group communication (without the involvement of the V2X application server).

9.12.2 Information flows

9.12.2.1 Push Layer-2 group ID mapping

Table 9.12.2.1-1 describes the information flow push layer-2 group ID mapping from the VAE server to the VAE client and between the VAE clients.

Editor’s note: Whether the procedures and information flows for dynamic group management are to be moved to SEAL is FFS.

Table 9.12.2.1-1: Push Layer-2 group ID mapping

Information element	Status	Description
Dynamic group information	M	Group information including dynamic group ID, group definition, group leader ID
ProSe Layer-2 Group ID	M	ProSe Layer-2 Group ID corresponding to the dynamic group information

9.12.2.2 Configure dynamic group request

Table 9.12.2.2-1 describes the information flow for configure dynamic group request from the V2X application specific sever to the VAE server.

Table 9.12.2.2-1: Configure dynamic group request

Information element	Status	Description
Dynamic group information	M	Group information including dynamic group ID, group definition, group leader ID
Endpoint information	M	End point information to which the configure dynamic group notification has to be sent

9.12.2.3 Configure dynamic group response

Table 9.12.2.3-1 describes the information flow for configure dynamic group response from the VAE server to the V2X application specific sever.

Table 9.12.2.3-1: Configure dynamic group response

Information element	Status	Description
Result	M	Result from the VAE server in response to the configure dynamic group request.

9.12.2.4 Configure dynamic group notification

Table 9.12.2.4-1 describes the information flow for configure dynamic group notification from the VAE server to the V2X application specific sever.

Table 9.12.2.4-1: Configure dynamic group notification

Information element	Status	Description
Dynamic group information	M	Group information including dynamic group ID, UE ID (joined or left UE(s))

9.12.2.5 Identity list notification

Table 9.12.2.5-1 describes the information flow identity list notification from the VAE client to the VAE server.

Table 9.12.2.5-1: Identity list notification

Information element	Status	Description
Dynamic group information	M	Group information including dynamic group ID, UE ID (joined or left UE(s))

9.12.2.6 Dynamic group information update request

Table 9.12.2.6-1 describes the information flow for dynamic group information update request from the VAE Client to the VAE server.

Table 9.12.2.6-1: Dynamic group information update request

Information element	Status	Description
Dynamic group information to update	M	Dynamic group information to update, e.g. group leader ID
Endpoint information	M	End point information to which response has to be sent

9.12.2.7 Dynamic group information update response

Table 9.12.2.7-1 describes the information flow for dynamic group information update response from the VAE server to the VAE client.

Table 9.12.2.7-1: Dynamic group information update consent response

Information element	Status	Description
Result	M	Result from the VAE server in response to the Dynamic group information update request.

9.12.2.8 Dynamic group information update consent request

Table 9.12.2.8-1 describes the information flow for dynamic group information update consent request from the VAE Server to the VAE client from whom consent is required.

Table 9.12.2.8-1: Dynamic group information update consent request

Information element	Status	Description
Information for consent	M	Dynamic group information for consent, e.g. group leader ID

9.12.2.9 Dynamic group information update consent response

Table 9.12.2.9-1 describes the information flow for dynamic group information update consent response from the VAE client to the VAE server.

Table 9.12.2.9-1: Dynamic group information update consent response

Information element	Status	Description
Result	M	Result from the VAE server in response to the Dynamic group information update consent request.

9.12.2.10 Dynamic group information update notification

Table 9.12.2.10-1 describes the information flow for dynamic group information update notification from the VAE server to the V2X application specific sever.

Table 9.12.2.10-1: Dynamic group information update notification

Information element	Status	Description
Dynamic group information	M	Dynamic group information which has been updated, e.g. group leader ID

9.12.2.11 Dynamic group information update indication

Table 9.12.2.11-1 describes the information flow for group information update indication from the VAE server to the VAE client.

Table 9.12.2.11-1: Dynamic group information update notification

Information element	Status	Description
Dynamic group information	M	Dynamic group information for which update request has been received, e.g. group leader ID

9.12.2.12 Dynamic group information update consent request (Off network)

Table 9.12.2.12-1 describes the information flow for group information update request from the VAE client to the VAE client.

Table 9.12.2.12-1: Group information update request

Information element	Status	Description
Information for consent	M	Dynamic group information for consent, e.g. group leader ID

9.12.2.13 Dynamic group information update consent response (Off network)

Table 9.12.2.13-1 describes the information flow for group information update consent response from the VAE client to the VAE server.

Table 9.12.2.13-1: Dynamic group information update consent response

Information element	Status	Description
Result	M	Result from the VAE server in response to the Dynamic group information update consent request.

9.12.3 On-network dynamic group creation

9.12.3.1 General

The V2X application specific server is responsible for V2X dynamic group formation (including information like group ID assignment, group definition), membership management (e.g. user authorization). VAE layer supports V2X UEs in the Uu communication range assigning a ProSe Layer-2 Group ID for application layer V2X dynamic group formation.

9.12.3.2 Procedure

The procedure for on-network dynamic group creation is illustrated in figure 9.12.3.2-1.

Pre-condition:

1. V2X application dynamic group is defined at the V2X application specific server with V2X UE assigned as dynamic group leader.

2. VAE server has a pool of the ProSe Layer-2 Group IDs that can be assigned to dynamic groups

Figure 9.12.3.2-1: On-network dynamic group creation

1. The V2X application specific server requests the VAE server to configure dynamic group corresponding to the dynamic group information (e.g. dynamic group ID, group definition, group leader).

2. To enable PC5 communication, the VAE server assigns ProSe Layer-2 Group ID to the received dynamic group information from the available ProSe Layer-2 Group ID pool.

3. The VAE server responds to the V2X application specific server for the request to configure dynamic group.

4. The VAE server triggers a push request including ProSe Layer-2 Group ID corresponding to the dynamic group information to the VAE client.

5. The VAE client stores the received PC5 communication parameters corresponding to the dynamic group information received from the VAE server.

NOTE 1: The VAE client may further announce the dynamic group information including the corresponding ProSe Layer-2 Group ID to the other VAE clients within the PC5 communication proximity on a PC5 channel dedicated for V5-AE communications, enabling more V2X UEs to join the dynamic group.

NOTE 2: When there is loss of connectivity with the network by the V2X UEs, service continuity is ensured by the V2X UEs switching to PC5 communication using the VAE server assigned ProSe Layer-2 Group ID corresponding to the dynamic group formation.

9.12.4 Off-network dynamic group creation

9.12.4.1 General

The V2X application specific client is responsible for V2X dynamic group information (including information like group ID assignment, group definition). VAE layer on the client supports assigning a ProSe Layer-2 Group ID for application layer V2X dynamic group formation.

9.12.4.2 Procedure

The procedure for off-network dynamic group creation is illustrated in figure 9.12.4.2-1.

Pre-condition:

1. VAE clients are provisioned ProSe Layer-2 Group ID(s) generation rules corresponding to the group information or

2. VAE client(s) are configured with the unique pool of ProSe Layer-2 Group IDs, when they are in coverage area of the VAE server.

Figure 9.12.4.2-1: Off-network dynamic group creation

1. The V2X application specific client 2 requests the VAE client 2 to configure dynamic group corresponding to the dynamic group information (e.g. dynamic group ID, group definition, group leader).

2. Each VAE client generates ProSe Layer-2 Group ID independently based on the provisioned ProSe Layer-2 Group ID(s) generation rules for its group information or the VAE client 2 assigns ProSe Layer-2 Group ID from the pool of configured ProSe Layer-2 Group IDs.

3. VAE client may further announce the dynamic group information including the corresponding ProSe Layer-2 Group ID to the other VAE clients within the PC5 communication proximity on a PC5 channel dedicated for V5-AE communications, enabling more V2X UEs to join the dynamic group.

4. The VAE client stores the PC5 communication parameters corresponding to the dynamic group information received from another VAE client.

9.12.5 On-network dynamic group notification

9.12.5.1 General

Once the on-network dynamic group is created as defined in subclause 9.12.3, the VAE client notifies the VAE server about changes in the group (i.e. UE joins or leaves the group) and finally the V2X application specific server is notified with such information.

9.12.5.2 Procedure

The procedure for on-network dynamic group notification is illustrated in figure 9.12.5.2-1.

Pre-condition:

1. V2X application dynamic group is created as defined in subclause 9.12.3.

Figure 9.12.5.2-1: On-network dynamic group notification

1. The VAE client sends identity list notification to the VAE server about group member changes.

2. Upon receipt of the identity list notification from the VAE client, the VAE server further notifies the V2X application specific server about the newly joined or left group member(s).

9.12.6 On network dynamic group information update procedure

9.12.6.1 General

This subclause provides procedures to update dynamic group information of an on-network V2X dynamic group.

9.12.6.2 VAE client initiated on network dynamic group information update procedure

The procedure for on-network dynamic group information (e.g. group leader) update is illustrated in figure 9.12.6.2-1.

Pre-conditions:

1. The on network dynamic group has already been defined and V2X UE A and V2X UE B are members of the group;

2. V2X UE A is the current group leader; and

3. The V2X application specific client in V2X UE A has determined to update the group information (e.g., update group leader ID from identity of V2X UE A to identity of V2X UE B) and informed the updates and other relevant information about the update (e.g. if the update is temporary, like time bound, or permanent) to VAE client A to update the group information.

Figure 9.12.6.2-1: VAE client initiated on network dynamic group information update procedure

1. The VAE client A sends a Dynamic group information update request to the VAE server. The request includes the group-ID of the group for which group information update request is sent. The request also includes the updated group information (e.g. identity of V2X UE B as group leader ID) and other relevant information about the update (e.g. if the update to the group information are temporary and time bound or permanent).

2. Upon receiving the Dynamic group information update request from VAE client A, the VAE server checks for the V2X user authorization to update the group information. If required, the VAE server also checks validity of the updated group information (e.g. if the request is to update the group leader ID to V2X UE B, the VAE server checks with V2X application specific server about the capabilities of the proposed group leader V2X UE B to ensure it is capable of sufficient fuel, sensors and applications to communicate and coordinate with other group members to act as group leader). If required, then the VAE server consults with V2X application specific server to ratify the updated group information or seek changes to the requested update (e.g. a different V2X UE as group leader). If the authorization fails or if the updated group information is not valid, then steps 3 to 6 are skipped.

3. If the request from the VAE client is authorized and the updated group information is valid, the VAE server acknowledges the VAE client A.

4. If the update in group information requires consent from other group member(s) (e.g. consent from the proposed new group leader, V2X UE B, to accept the role of group leader), then the VAE server obtains the consent from the user as specified in clause 9.12.6.4. This step is skipped if user consent is not required.

5. The VAE server sends the Dynamic group information update change response to VAE client A indicating success or failure. If:

– the request was authorized but the updated group information was not valid, as determined in step 2; or

– a reject response to the Dynamic group information update consent request was received from VAE client B;

then, the VAE server may include suggestions for the updated group information (e.g. identity of the V2X UE C as potential group leader). These suggestions are based on consultation with the V2X application specific server.

6. If the group information update request was successful, the VAE server updates the group document.

7. Upon successful update of the group document, the VAE server triggers a group information update notification to other group members and to the V2X application specific server.

9.12.6.3 VAE server initiated on network dynamic group information update procedure

The procedure for on-network dynamic group information (e.g. group leader) update is illustrated in figure 9.12.6.3-1.

Pre-conditions:

1. The on network dynamic group has already been defined and V2X UE A and V2X UE B are members of the group;

2. V2X UE A is the current group leader; and

3. The V2X application specific server has determined to update the group information (e.g., update group leader ID from identity of V2X UE A to identity of V2X UE B) and informed the updates and other relevant information about the update (e.g. if the update is temporary, like time bound, or permanent) to the VAE server to update the group information.

Figure 9.12.6.3-1: VAE server initiated on network dynamic group information update procedure

1. If the update in group information requires consent from the group member(s) (e.g. consent from the proposed new group leader, V2X UE B, to accept the role of group leader), then the VAE server obtains the consent from the user as specified in clause 9.12.6.4. This step is skipped if user consent is not required.

2. If required (e.g. when group leader ID is being changed from V2X UE A to V2X UE B), the VAE server sends Dynamic group information update indication to the VAE client A about the possible update to group information.

NOTE: Step 1 and step 2 can happen in parallel.

3. Upon receiving the indication from the VAE server, the VAE client A notifies the V2X application specific client A about the possible update to group information.

4. If group leader information update request is successful, the VAE server updates the group document.

5. Upon successful update of the group document, the VAE server triggers a Dynamic group information update notification to other group members and to the V2X application specific server.

9.12.6.4 VAE Server taking consent from user

The procedure for the VAE server to take consent form the user is illustrated in figure 9.12.6.4-1.

Pre-conditions:

1. VAE client A has initiated dynamic group information update procedure as specified in clause 9.12.6.2, or the V2X application specific server has determined to update the dynamic group information.

Figure 9.12.6.4-1: VAE Server taking consent from user procedure

1. If the update in group information requires consent from other group member(s) (e.g. consent from the proposed new group leader, V2X UE B, to accept the role of group leader), then the VAE server sends a dynamic group information update consent request to VAE client B. The request includes the group-ID of the group for which the request is sent. The request also includes other relevant information about the update (e.g. if the update to the group information are temporary and time bound or permanent).

2. The VAE client B notifies the V2X application specific client B about the Dynamic group information update consent request. The V2X application specific client or the V2X user decides to accept or reject the request.

3. The VAE client B sends a Dynamic group information update consent response to the VAE server. The response includes the decision whether the request is accepted or rejected.

9.12.7 Off network dynamic group information update procedure

This subclause provides procedures to update dynamic group information of an off-network V2X dynamic group.

The procedure for off-network dynamic group information update procedure is illustrated in figure 9.12.7-1.

Pre-conditions:

1. The off network dynamic group has already been defined and V2X UE A and V2X UE B are members of the group;

2. V2X UE A is the current group leader;

Figure 9.12.7-1: Off network dynamic group information update procedure

1. If the update in group information requires consent from other group member(s) (e.g. consent from the proposed new group leader, V2X UE B, to accept the role of group leader), then the VAE client sends a dynamic group information update consent request to VAE client B. The request includes the updated group information along with the group-ID of the group. The request also includes other relevant information about the update (e.g. if the update to the group information are temporary and time bound or permanent).

2. The VAE client B notifies the V2X application specific client B about the Dynamic group information update consent request and the V2X application specific client or the V2X user decides to accept or reject the request.

3. The VAE client B sends a Dynamic group information update response to the VAE client A. The response includes the decision whether the request is accepted or rejected.

4. If the group information update consent request is successful, then the VAE client A sends notification to other group members.