6 VAE procedures

24.4863GPPProtocol aspectsRelease 17Stage 3TSVehicle-to-Everything (V2X) Application Enabler (VAE) layer

6.1 General

6.2 V2X UE registration procedure

6.2.1 Client procedure

Upon receiving a request from a V2X application to register for receiving V2X messages from the V2X AS, the VAE-C shall generate an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response message for V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <registration-info> element in the <VAE-info> root element:

1) shall include a <V2X-UE-id> element set to the identity of the UE which requests the registration;

2) shall include a <reception-uri> element set to the URI for subsequent messages to the VAE-C; and

3) shall include one or more <V2X-service-id> element(s), each element set to the V2X service ID which the V2X UE is interested in receiving; and

d) shall send the HTTP POST request towards the VAE-S according to IETF RFC 7231 [19].

6.2.2 Server procedure

Upon reception of an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <registration-info> element in the <VAE-info> root element

the VAE-S:

a) shall store the received registration information;

b) shall generate an HTTP 200 (OK) response according to IETF RFC 7231 [19]. In the HTTP 200 (OK) response message, the VAE-S:

1) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

2) shall include an application/vnd.3gpp.vae-info+xml MIME body and in the <VAE-info> root element:

i) shall include a <registration-info> element with a <result> child element set to the value "success" or "failure" indicating success or failure of the registration; and

ii) if success and if the V2X service IDs as present in the <registration-info> element of the received HTTP POST request is not fully acceptable to the VAE-S, the VAE-S may change the V2X service IDs to a subset and shall include one or more <V2X-service-id> child elements set to the identities of the new V2X service IDs; and

c) shall send the HTTP 200 (OK) response towards the VAE-C.

6.3 V2X UE de-registration procedure

6.3.1 Client procedure

Upon receiving a request from a V2X application to de-register for receiving certain V2X service-IDs from the V2X AS, the VAE-C shall send an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response message for V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <de-registration-info> element in the <VAE-info> root element:

1) shall include a <V2X-UE-id> element set to the identity of a UE which requests the de-registration; and

2) shall include one or more <V2X-service-id> child element(s), each element set to the V2X service ID that the UE is no longer interested in receiving; and

d) shall send the HTTP POST request towards the VAE-S according to IETF RFC 7231 [19].

6.3.2 Server procedure

Upon reception of an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <de-registration-info> element in the <VAE-info> element in the <VAE-info> element,

the VAE-S:

a) shall remove the received V2X service IDs from registration information corresponding to the V2X UE;

b) shall generate an HTTP 200 (OK) response according to IETF RFC 7231 [19]. In the HTTP 200 (OK) response message, the VAE-S:

1) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

2) shall include an application/vnd.3gpp.vae-info+xml MIME body and in the <VAE-info> root element:

i) shall include a <de-registration-info> element with a <result> child element set to the value "success" or "failure" indicating success or failure of the de-registration; and

c) shall send the HTTP 200 (OK) response towards the VAE-C.

6.4 Application level location tracking procedure

6.4.1 Client procedure

Upon entering a new geographical area if the V2X UE has been provisioned with geographical identifier groups (see clause 7) and the V2X UE has subscribed to a certain geographical area identifier group in order to receive V2X messages from the V2X AS for this area, the VAE-C shall send an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response message for V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

c) shall include an application/vnd.3gpp.vae-info+xml MIME body and in the <location-tracking-info> element in the <VAE-info> root element:

1) shall include a <V2X-UE-id> element set to the identity of the UE that subscribes to a geographical area;

2) shall include a <geo-id> element set to the identity of the geographical area to be subscribed, i.e. the new geographical area where the UE entered; and

3) shall include an <operation> element set to "subscribe".

Upon a successful subscription to a geographical area, the VAE-C shall send an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response message for the V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

c) shall include an application/vnd.3gpp.vae-info+xml MIME body and in the <location-tracking-info> element in the <VAE-info> root element:

1) shall include a <V2X-UE-id> element set to the identity of the UE that unsubscribes to a geographical area;

2) shall include a <geo-id> element set to the identity of the geographical area to be unsubscribed, i.e. the old geographical area where the UE exited; and

3) shall include an <operation> element set to "unsubscribe".

6.4.2 Server procedure

Upon reception of an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <VAE-info> root element with a <location-tracking-info> element with a <V2X-UE-id> element and an <operation> element set to "subscribe",

the VAE-S:

a) shall store the received geographical area information and associate this area with the UE identity provided in the <V2X-UE-id> element;

b) shall generate an HTTP 200 (OK) response according to IETF RFC 7231 [19]. In the HTTP 200 (OK) response message, the VAE-S:

1) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

2) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <location-tracking-info> element in the <VAE-info> root element:

i) shall include a <result> child element set to the value "success" or "failure" indicating success or failure of the subscription; and

ii) shall include an <operation> element set to "subscribe"; and

c) shall send the HTTP 200 (OK) response towards the VAE-C.

Upon reception of an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.VAE-registration-+xml MIME body with a <VAE-info> root element with a <location-tracking-info> element with an <V2X-UE-id> element and an <operation> element set to "unsubscribe",

the VAE-S:

a) shall remove the received geographical area information associated with the UE identity provided in the <V2X-UE-id> element;

b) shall generate an HTTP 200 (OK) response according to IETF RFC 7231 [19]. In the HTTP 200 (OK) response message, the VAE-S:

1) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

2) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <location-tracking-info> element in the <VAE-info> root element:

i) shall include a <result> child element set to the value "success" or "failure" indicating success or failure of the unsubscription; and

ii) shall include an <operation> element set to "unsubscribe"; and

c) shall send the HTTP 200 (OK) response towards the VAE-C.

6.5 V2X message delivery procedure

6.5.1 Client procedure

6.5.1.1 Reception of a V2X message

Upon receiving an HTTP POST request containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <payload>element included in the <message-info> element in the <VAE-info> root element;

the VAE-C:

a) shall provide the received information to the V2X application identified by the service indicated in the V2X message, if the identity or group of theV2X message matches the identity of the V2X UE or the group of the VAE client; and

b) shall send a V2X message reception report as specified in clause 6.5.1.3 if the <message-reception-ind> element and <message-reception-uri> element are included in the received V2X message.

6.5.1.2 Reception of a V2X message reception report

Upon receiving an HTTP POST request containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <result> element included in the <message-info> root element;

the VAE-C:

a) evaluates the content of the <result> element.

6.5.1.3 Sending of a V2X message reception report

In order to send a V2X message reception report, the VAE-C shall generate an HTTP 200(OK) response message according to procedures specified in IETF RFC 7231 [19]. In the HTTP 200(OK) message, the VAE-C:

a) shall set the Request-URI to the URI included in the <message-reception-uri> element in the received HTTP POST request message for the V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <reception-report> element included in the <VAE-info> root element. In the <reception-report> element, the VAE-C:

1) shall include a <result> element set to a value "success" or "fail" indicating success or failure of the V2X message reception.

6.5.1.4 Sending of a V2X message

In order to send a V2X message, the VAE-C shall send an HTTP POST request message according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request message, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response message for V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

c) shall include an application/vnd.3gpp.vae-info+xml MIME body and in the <message-info> element in the <VAE-info> root element:

1) shall include a <V2X-UE-id> element set to the identity of the UE which requests the sending of the V2X message;

2) shall include a <V2X-service-id> element set to the identity of the V2X service which is interested in sending the V2X message;

3) may include one or more <geo-id> element(s), each element set to the identity of the geographical area containing the location of the V2X UE;

4) may include a <message-reception-ind> element to indicate to the VAE server that a reception report is required; and

5) if a <message-reception-ind> element is included, shall include a <message-reception-uri> element set to the URI for a response to the VAE-C.

6.5.2 Server procedure

6.5.2.1 Reception of a V2X message

Upon receiving an HTTP POST request containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <payload> element included in the <message-info> element in the <VAE-info> root element;

the VAE-S:

a) shall provide the received information to the V2X application server identified by the service indicated in the V2X message; and

b) shall send a V2X message reception report as specified in clause 6.5.2.3 if the <message-reception-ind> element and <message-reception-uri> element are included in the received V2X message.

6.5.2.2 Reception of a V2X message reception report

Upon receiving an HTTP POST request containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <result> element included in the <message-info> element in the <VAE-info> root element;

the VAE-S:

a) evaluates the content of the <result> element.

6.5.2.3 Sending of a V2X message reception report

In order to send a V2X message reception report, the VAE-S shall send a HTTP POST request message according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request message, the VAE-S:

a) shall set the Request-URI to the URI included in the <message-reception-uri> element in the received HTTP POST request message for reception of a V2X message (see clause 6.5.2.1);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

c) shall include an application/vnd.3gpp.vae-info+xml MIME body and a <result> element of the <message-info> element set to a value "success" or "fail".

6.5.2.4 Sending of a V2X message to target geographical areas

In order to send a V2X message received from a V2X application server to target geographical areas, the VAE-S shall send a HTTP POST request message to each VAE-C associated with the target geographical area according to procedures specified in IETF RFC 7231 [19]. In each HTTP POST request message, the VAE-S:

a) shall set the Request-URI to the URI included in the received HTTP response message for V2X UE registration procedure (see clause 6.2) for the VAE-C identified by a <V2X-UE-id> element, determined by association from the target geographical area indicated by the V2X application server;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

c) shall include an application/vnd.3gpp.vae-info+xml MIME body and in the <message-info> element in the <VAE-info> root element:

1) shall include a <V2X-UE-id> element set to the identity of the UE to receive the V2X message, determined by association from the target geographical area indicated by the V2X application server;

2) shall include a <V2X-service-id> element set to the identity of the V2X service which is interested in sending the V2X message;

3) may include a <geo-id> element set to the identity of the geographical area containing the location of the V2X UE;

4) may include a <message-reception-ind> element to indicate to the VAE server that a reception report is required; and

5) if a <message-reception-ind> element is included, shall include a <message-reception-uri> element set to the URI for a response to the VAE-S.

6.5.2.5 Sending of a V2X message to a V2X group

In order to send a V2X message received from a V2X application server, the VAE-S shall send a HTTP POST request message according to procedures specified in IETF RFC 7231 [19] to each VAE-C which has registered for the V2X message delivery service. In the HTTP POST request message, the VAE-S:

a) shall set the Request-URI to the URI of each VAE-C registered for V2X message delivery service (see clause 6.2);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

c) shall include an application/vnd.3gpp.vae-info+xml MIME body and in the <message-info> root element:

1) shall include a <V2X-group-id> child element set to the V2X group identity of the VAE-C to receive the V2X message, determined by registration with the identity of the V2X group indicated by the V2X application server;

2) shall include a <V2X-service-id> element set to the identity of the V2X service which is interested in sending the V2X message;

3) may include a <geo-id> element set to the identity of the geographical area applicable for the V2X message;

4) may include a <message-reception-ind> element to indicate to the VAE-C that a reception report is required; and

5) if a <message-reception-ind> element is included, shall include a <message-reception-uri> element set to the URI for a response to the VAE-C.

6.6 V2X service discovery procedure

6.6.1 Client procedure

In order to discover V2X service information from a VAE-S (e.g. available VAE services identified by V2X service identities), the VAE-C shall send an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-C:

a) shall set the Request-URI to the URI received in the VAE client UE configuration document via the SCM-S;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

c) shall include an application/vnd.3gpp.vae-info+xml MIME body and in the <service-discovery-info> element in the <VAE-info> root element:

1) shall include a <V2X-UE-id> element set to the identity of the UE which requests the service discovery.

6.6.2 Server procedure

Upon reception of an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <service-discovery-info> element in the <VAE-info> root element,

the VAE-S:

a) shall generate an HTTP 200 (OK) response according to IETF RFC 7231 [19]. In the HTTP 200 (OK) response message, the VAE-S:

1) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

2) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <service-discovery-info> element in the <VAE-info> root element:

i) shall include a <result> child element set to the value "success" or "failure" indicating success or failure of getting the service discovery information; and

ii) if <result> element is set to "success", shall include a <service-discovery-data> element with one or more <V2X-service-map> element(s), each <V2X-service-map> element shall include:

A) one or more <V2X-service-id> element(s) set to the identities of the available V2X service IDs; and

B) a <V2X-AS-address> element set to the V2X AS address; and

b) shall send the HTTP 200 (OK) response towards the VAE-C.

6.7 V2X service continuity procedure

6.7.1 Client procedure

In order to obtaining dynamic local V2X service information from a VAE-S, the VAE-C shall send an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response message for V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

c) shall include an application/vnd.3gpp.vae-info+xml MIME body and in the <local-service-info> element in the <VAE-info> root element:

1) shall include a <V2X-UE-id> element set to the identity of the UE which requests the local service information; and

2) shall include a <geo-id> element set to the identity of the geographical area for which the local service information is requested.

6.7.2 Server procedure

Upon reception of an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with an <V2X-UE-id> element and a <geo-id> element in the <local-service-info> element in the <VAE-info> root element;

the VAE-S:

a) shall determine the local service information (e.g. V2X server USD(s), V2X USD) corresponding to the geographical location information received in <geo-id>; and

b) shall generate an HTTP 200 (OK) response according to IETF RFC 7231 [19]. In the HTTP 200 (OK) response message, the VAE-S:

1) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

2) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <local-service-info> element in the <VAE-info> root element:

i) shall include a <result> child element set to the value "success" or "failure" indicating success or failure of getting the local service information; and

ii) if the result is "success", the VAE-S shall include a <local-service-info-content> element which provides the local service information to the VAE-C; and

c) shall send the HTTP 200 (OK) response towards the VAE-C.

6.8 Dynamic group management procedure

6.8.1 On-network dynamic group creation procedure

6.8.1.1 Server procedure

Upon receiving a Configure Dynamic Group request from a V2X application specific server (see 3GPP TS 29.486 [22]) the VAE-S shall assign a ProSe Layer-2 Group ID to the received dynamic group information from the available ProSe Layer-2 Group ID pool. Then the VAE-S shall generate an HTTP PUT request message according to procedures specified in IETF RFC 7231 [19]. In the HTTP PUT request message, the VAE-S:

a) shall include a Request-URI set to the URI corresponding to the identity of the VAE-C of the group leader;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info +xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <layer2-group-id-mapping> element in the <VAE-info> root element which shall include:

1) a <dynamic-group-info> element which shall include:

i) a <dynamic-group-id> element set to the identity of the dynamic group;

ii) a <group-definition> element set to information about the V2X group; and

iii) a <group-leader-id> element set to the identity of the group leader; and

2) a <prose-layer2-group-id> element corresponding to the dynamic group information; and

d) shall send the HTTP PUT request message towards the VAE-C according to IETF RFC 2616 [19].

6.8.1.2 Client procedure

Upon receiving an HTTP PUT request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info +xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <layer2-group-id-mapping> element in the <VAE-info> root element;

the VAE-C shall store the content of the <layer2-group-id-mapping> element and 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.

6.8.2 On-network dynamic group notification procedure

6.8.2.1 Client procedure

Once the on-network dynamic group is created as defined in clause 6.8.1, if the group changes (i.e. UE joins or leaves the group), the VAE-C shall generate an HTTP POST request message according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-C:

a) shall include a Request-URI set to the URI corresponding to the identity of the VAE-S;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info +xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with an <id-list-notification> element in the <VAE-info> root element which shall include:

1) a <dynamic-group-id> element set to the identity of the dynamic group; and

2) one or more <group-member-id> element(s), each of which contains a <V2X-UE-id> child element set to the identity of the joined or left V2X UE and a <group-scope> child element that has the value "joined" or "left"; and

d) shall send the HTTP POST request message towards the VAE-S according to IETF RFC 7231 [19].

6.8.2.2 Server procedure

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info +xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with an <id-list-notification> element in the <VAE-info> root element;

the VAE-S shall send Notify Dynamic Group request (see 3GPP TS 29.486 [22]) towards the V2X application specific server according to IETF RFC 7231 [19].

6.8.3 VAE client initiated on network dynamic group information update procedure

6.8.3.1 Client procedure

In oder to update dynamic group information of an on-network V2X dynamic group, the VAE-C shall generate an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response message for the V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <dynamic-group-update-info> element included in the <VAE-info> root element which:

1) shall include a <dynamic-group-info> element which shall include at least one of the followings;

i) a <dynamic-group-id> element set to the identity of the dynamic group;

ii) a <group-definition> element set to information about the V2X group; and

iii) a <group-leader-id> element set to the identity of the new group leader; and

2) shall include an <endpoint-info> element set to the end point information to which response has to be sent;

d) shall send the HTTP POST request towards the VAE-S according to IETF RFC 7231 [19].

6.8.3.2 Server procedure

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info +xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with an <dynamic-group-update-info> element in the <VAE-info> root element;

the VAE-S:

a) shall check for the V2X user authorization to update the group information, and

1) if the authorization fails or if the updated group information is not valid, respond with a HTTP 403 (Forbidden) response to the HTTP POST request and skip rest of the steps;

b) if the update in group information requires consent from other group member(s), shall obtain the consent from the user as specified in clause 6.8.5;

c) shall generate an HTTP 200 (OK) response according to IETF RFC 7231 [19]. In the HTTP 200 (OK) response message, the VAE-S:

1) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

2) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <dynamic-group-update-info> element in the <VAE-info> root element which:

i) shall include a <result> child element set to the value "success" or "failure" indicating success or failure of the Dynamic group information update request;

Editor’s note: Suggestions for the updated group information is FFS.

d) shall send the HTTP 200 (OK) response towards the VAE-C; and

e) shall update the group document as specified in clause 6.2.5.1 of TS 24.544 [9].

6.8.4 VAE server initiated on network dynamic group information update procedure

6.8.4.1 Client procedure

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info +xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with an <dynamic-group-info-update-indication> element in the <VAE-info> root element;

the VAE-C:

a) shall notify the V2X application specific client about the possible update to group information.

6.8.4.2 Server procedure

In oder to update dynamic group information of an on-network V2X dynamic group, if the update in group information requires consent from the group member(s), the VAE-S shall obtain the consent from the user as specified in clause 6.8.5 and shall generate an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-S:

a) shall include a Request-URI set to the URI corresponding to the identity of the VAE-C;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info +xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <dynamic-group-info-update-indication> element in the <VAE-info> root element which shall include:

1) a <dynamic-group-info> element which shall include:

i) a <dynamic-group-id> element set to the identity of the dynamic group;

ii) a <group-definition> element set to information about the V2X group; and

iii) a <group-leader-id> element set to the identity of the new group leader;

d) shall send the HTTP POST request message towards the VAE-C according to IETF RFC 7231 [19]; and

e) shall update the group document as specified in clause 6.2.5.1 of TS 24.544 [9].

6.8.5 VAE Server taking consent from user procedure

6.8.5.1 Client procedure

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info +xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with an <dynamic-group-update-consent-info> element in the <VAE-info> root element;

the VAE-C:

a) shall notify the V2X application specific client about the dynamic group information update consent request.

Upon receiving the result of dynamic group information update consent request from the V2X application specific client, the VAE-C:

b) shall send an HTTP 200(OK) response message including a <dynamic-group-update-consent-info> element with a <result> child element set to "accept" or "reject" in the <VAE-info> root element indicating acceptance or rejection of the request by the V2X user.

6.8.5.2 Server procedure

If the update in group information requires consent from other group member(s), the VAE-S shall generate an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-S:

a) shall include a Request-URI set to the URI corresponding to the identity of the VAE-C;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info +xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <dynamic-group-update-consent-info> element in the <VAE-info> root element which shall include:

1) a <dynamic-group-info> element which shall include:

i) a <dynamic-group-id> element set to the identity of the dynamic group;

ii) a <group-definition> element set to information about the V2X group; and

iii) a <group-leader-id> element set to the identity of the group leader; and

d) shall send the HTTP POST request message towards the VAE-C according to IETF RFC 7231 [19].

6.9 Network monitoring by the V2X UE procedure

6.9.1 V2X UE subscription for network monitoring information

6.9.1.1 Client procedure

In order to subscribe for the network monitoring information from the VAE-S, the VAE-C shall send an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-C:

a) shall set the Request-URI to the URI corresponding to the identity of the VAE-S;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <network-monitoring-subscription-info> element in the <VAE-info> root element:

1) shall include a <V2X-UE-id> element set to the identity of the UE which requests the registration;

2) shall include a <subscription-events> element with one or more <event> child element set to the network monitoring events (e.g. uplink degradation, congestion, overload, coverage) to be subscribed; and

3) shall include a <triggering-criteria> element set to the criteria to indicate when the VAE-S sends the monitoring reports to the VAE-C.

6.9.1.2 Server procedure

Upon reception of an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <network-monitoring-subscription-info> element in the <VAE-info> root element;

the VAE-S:

a) shall store the received subscription information if the VAE-C is authorized and allowed to access the network monitoring information;

b) shall generate an HTTP 200 (OK) response according to IETF RFC 7231 [19]. In the HTTP 200 (OK) response message, the VAE-S:

1) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

2) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <network-monitoring-subscription-info> element in the <VAE-info> root element:

i) shall include a <V2X-UE-id> element set to the identity of the V2X UE subscribing the network monitoring information; and

ii) shall include a <result> child element set to the value "success" or "failure" indicating success or failure of subscribing the network monitoring information; and

c) shall send the HTTP 200 (OK) response towards the VAE-C.

6.9.2 Notifications for network monitoring information

6.9.2.1 Server procedure

Based on the UE subscription for network monitoring information, the VAE-S shall generate an HTTP POST request message according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-S:

a) shall include a Request-URI set to the URI corresponding to the identity of the VAE-C;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info +xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <network-monitoring-info-notification> element in the <VAE-info> root element which shall include:

1) a <V2X-UE-id> element set to the identity of the subscribed V2X UE;

2) a <network-monitoring-info> element, which:

i) shall include one or more <trigger-id> elements set to the identity of the triggering criteria that resulted in the VAE-S sending the monitoring report to the VAE-C;

ii) may include an <uplink-quality-level> element set to the uplink quality level;

iii) may include a <congestion-info> element set to the congestion value;

iv) may include a <geographical-area> element which shall include at least one of the followings:

A) <cell-area>, an element specifying an NCGI which when entered triggers a request for a location report coded as specified in clause 19.6A in 3GPP TS 23.003 [2] for which the monitoring applies; and

B) <tracking-area>, an element specifying a tracking area identity coded as specified in clause 19.4.2.3 in 3GPP TS 23.003 [2] for which the monitoring applies;

v) may include a <time-validity> element set to the period for which the monitoring applies; and

vi) may include an <MBMS-level> element, which may include:

A) an <MBMS-coverage-level> element set to the coverage level for MBMS; and

B) an <MBMS-bearer-level-event> element set to the MBMS bearer level events; and

d) shall send the HTTP POST request message towards the VAE-C according to IETF RFC 7231 [19].

6.10 PC5 Provisioning in multi-operator V2X scenarios procedure

6.10.1 Client procedure

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <PC5-provisioning-status-info> element;

the VAE-C shall generate an HTTP 200(OK) response message according to IETF RFC 7231procedures specified in  [19]. In the HTTP 200(OK) response, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response for the V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <PC5-provisioning-status-info> element included in the <VAE-info> root element which:

1) shall include a <result> element set to the value "success" or "failure" indicating success or failure of the PC5 provisioning status request; and

2) shall include a <PC5-policy-status-report> corresponding to the PC5 policy status request; and

d) shall send the HTTP 200(OK) response towards the VAE-S according to IETF RFC 7231 [19].

6.10.2 Server procedure

Upon receiving a V2X PC5 provisioning requirement from the V2X application specific server, the VAE-S:

a) may generate an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-S:

1) shall set the Request-URI to the URI corresponding to the identity of the V2X UE;

2) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

3) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <PC5-provisioning-status-info> element in the <VAE-info> root element which:

A) shall include a <VAE-server-id> element set to the identity of the VAE server which is requester of the PC5 parameters status;

B) shall include a <V2X-service-id> element set to the identity of the V2X service for which the VAE server’s request corresponds to; and

C) may include a <PC5-provisioning-status-report-configuration> element set to the configuration of the VAE-client reporting related to the PC5 Policy status, and optionally PC5 events like PC5 unavailability, PQI load info; and

4) shall send the HTTP POST request towards the VAE-C according to IETF RFC 7231[19];

NOTE: if step a) is performed, the VAE-S shall wait the response of step a) from the VAE-C and then perform step b).

6.11 Obtaining dynamic information of the UEs in proximity range procedure

6.11.1 Client procedure

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <subscribe-dynamic-info> element;

the VAE-C shall generate an HTTP 200(OK) response message according to procedures specified in IETF RFC 7231  [19]. In the HTTP 200(OK) response, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response for the V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <subscribe-dynamic-info> element included in the <VAE-info> root element which:

1) shall include a <result> element set to the value "success" or "failure" indicating success or failure of the subscribe dynamic information request; and

2) shall include a <configuration-report> element corresponding to the <reporting-configuration> element; and

d) shall send the HTTP 200(OK) response towards the VAE-S according to IETF RFC 7231 [19].

6.11.2 Server procedure

In order to manage the dynamic UE location group, the VAE-S shall generate an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-S:

a) shall set the Request-URI to the URI corresponding to the identity of the V2X UE;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <subscribe-dynamic-info> element in the <VAE-info> root element which:

1) shall include a <V2X-UE-id> element set to the identity of the UE who are part of the dynamic UE location group; and

2) shall include a <reporting-configuration> element indicating which configuration the UE should report (e.g. frequency of reporting, event based); and

d) shall send the HTTP POST request towards the VAE-C according to IETF RFC 7231 [19].

6.12 V2X groupcast/broadcast configuration by VAE layer procedure

6.12.1 Client procedure

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <V2X-groupcast/broadcast-configuration-info> element;

the VAE-C shall generate an HTTP 200(OK) response message according to procedures specified in IETF RFC 7231 [19]. In the HTTP 200(OK) response, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response for the V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <V2X-groupcast/broadcast-configuration-info> element included in the <VAE-info> root element which:

1) shall include a <result> element set to the value "success" or "failure" indicating success or failure of the V2X groupcast/broadcast configuration request; and

d) shall send the HTTP 200(OK) response towards the VAE-S according to IETF RFC 7231 [19].

6.12.2 Server procedure

Upon receiving an V2V configuration requirement request from the V2X application specific server, the VAE-S shall generate an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-S:

a) shall set the Request-URI to the URI corresponding to the identity of the V2X UE;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <V2X-groupcast/broadcast-configuration-info> element in the <VAE-info> root element which:

1) shall include a <V2X-server-id> element set to the identity of the VAE server which is requester of the V2X groupcast/broadcast configuration;

2) shall include a <V2X-group-id> element set to the V2X group identity for which the V2X groupcast/broadcast configuration is requested;

3) shall include a <V2X-service-id> element set to the V2X service ID for which the groupcast/broadcast configuration is requested;

4) shall include a <PC5-provisioning-policies> element indicating the PC5 provisioning policies/parameters to be used by the V2X-UEs within the V2X service;

5) may include a <relay-V2X-UE-id-list> element which shall include one or more <V2X-UE-id> child element(s), each of which set to the identity of the V2X UE to serve as application layer relays; and

6) may include a <minimum-number-of-transmissions> element set to the minimum number of allowed re-transmissions for the V2X message delivery; and

d) shall send the HTTP POST request towards the VAE-C according to IETF RFC 7231 [19].

6.13 Session-oriented services procedure

6.13.1 Client procedure

6.13.1.1 UE initiated session-oriented service establishment

In order to establish a session-oriented service with one or more V2X UEs (remote vehicle), the VAE-C (acting as remote controller) shall generate an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response for the V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-service-trigger-info> element included in the <VAE-info> root element which:

1) shall include a <V2X-UE-id> element set to the identity of the V2X UE which is the remote vehicle;

2) shall include a <V2X-service-id> element set to the V2X service ID for which application requirement corresponds to;

3) shall include a <V2X-application-specific-server-id-info> element set to the identity information of the V2X application specific server;

4) may include a <session-id> element set to the session identifier to be used for the session-oriented service; and

5) may include a <V2X-application-QoS-requirements> element indicating the application QoS requirements (reliability, delay, jitter) for the session-oriented service; and

d) shall send the HTTP POST request towards the VAE-S according to IETF RFC 7231 [19].

6.13.1.2 UE initiated session-oriented service update

In order to update a session-oriented service with one or more V2X UEs (remote vehicle), the VAE-C (acting as remote controller) shall generate an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response for the V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-change-trigger-info> element included in the <VAE-info> root element which shall include:

1) a <session-id> element set to the session identifier of the session-oriented service; and

2) a <V2X-application-QoS-requirements> element indicating the application QoS requirements (reliability, delay, jitter) for the session-oriented service that is to be updated; and

d) shall send the HTTP POST request towards the VAE-S according to IETF RFC 7231 [19].

6.13.1.3 UE initiated session-oriented service termination

In order to terminate a session-oriented service with one or more V2X UEs (remote vehicle), the VAE-C (acting as remote controller) shall generate an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response for the V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-termination-trigger-info> element included in the <VAE-info> root element which shall include:

1) a <session-id> element set to the session identifier of the session-oriented service that is to be terminated; and

d) shall send the HTTP POST request towards the VAE-S according to IETF RFC 7231 [19].

6.13.1.4 Session-oriented service establishment

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-service-info> element;

the VAE-C shall generate an HTTP 200(OK) response message according to procedures specified in IETF RFC 2616 [19]. In the HTTP 200(OK) response, the VAE-C:

a) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

b) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-service-info> element included in the <VAE-info> root element which shall include:

1) an <acknowledgement> element indicating the acknowledgement for the request; and

c) shall send the HTTP POST request towards the VAE-S according to IETF RFC 2616 [19] and send a session-oriented service establish notification to the V2X application-specific client.

6.13.1.5 Session-oriented service update

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-change-info> element;

the VAE-C shall generate an HTTP 200(OK) response message according to procedures specified in IETF RFC 2616 [19]. In the HTTP 200(OK) response, the VAE-C:

a) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

b) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-change-info> element included in the <VAE-info> root element which shall include an <acknowledgement> child element indicating the acknowledgement for the change request; and

c) shall send the HTTP POST request towards the VAE-S according to IETF RFC 2616 [19] and send a session-oriented service change notification to the V2X application-specific client.

6.13.1.6 Session-oriented service termination

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-termination-info> element;

the VAE-C shall generate an HTTP 200(OK) response message according to procedures specified in IETF RFC 2616 [19]. In the HTTP 200(OK) response, the VAE-C:

a) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

b) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-termination-info> element included in the <VAE-info> root element which shall include an <acknowledgement> element indicating the acknowledgement for the termination request; and

c) shall send the HTTP POST request towards the VAE-S according to IETF RFC 2616 [19] and send a session-oriented service termination notification to the V2X application-specific client.

6.13.2 Server procedure

6.13.2.1 UE initiated session-oriented service establishment

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-service-trigger-info> element,

the VAE-S shall generate an HTTP 200(OK) response message according to procedures specified in IETF RFC 7231 [19]. In the HTTP 200(OK) response, the VAE-S:

a) shall set the Request-URI to the URI corresponding to the identity of the V2X UE;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-service-trigger-info> element in the <VAE-info> root element which shall include an <acknowledgement> element indicating the acknowledgement for the request; and

d) shall send the HTTP POST request towards the VAE-C according to IETF RFC 7231 [19].

If the VAE-S acknowleges the request, the VAE-S shall perform the procedure to establish session oriented service with VAE client (e.g. remote vehicle).

Editor’s note: It is FFS to specify the procedure for VAE-S to establish session oriented service with VAE client (e.g. remote vehicle).

6.13.2.2 UE initiated session-oriented service update

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-service-change-info> element,

the VAE-S shall generate an HTTP 200(OK) response message according to procedures specified in IETF RFC 7231 [19]. In the HTTP 200(OK) response, the VAE-S:

a) shall set the Request-URI to the URI corresponding to the identity of the V2X UE;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-service-change-info> element in the <VAE-info> root element which shall include an <acknowledgement> element indicating the acknowledgement for the request; and

d) shall send the HTTP POST request towards the VAE-C according to IETF RFC 7231 [19].

If the VAE-S acknowleges the request, the VAE-S shall perform the procedure to change session oriented service with VAE client (e.g. remote vehicle).

Editor’s note: It is FFS to specify the procedure for VAE-S to change session oriented service with VAE client (e.g. remote vehicle).

6.13.2.3 UE initiated session-oriented service termination

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-service-termination-info> element,

the VAE-S shall generate an HTTP 200(OK) response message according to procedures specified in IETF RFC 7231 [19]. In the HTTP 200(OK) response, the VAE-S:

a) shall set the Request-URI to the URI corresponding to the identity of the V2X UE;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-service-termination-info> element in the <VAE-info> root element which shall include a <result> element indicating success or failure to terminate the session-oriented service; and

d) shall send the HTTP POST request towards the VAE-C according to IETF RFC 7231 [19].

If the VAE-S terminates the requested session successfully, the VAE-S shall perform the procedure to terminate session oriented service with VAE client (e.g. remote vehicle).

Editor’s note: It is FFS to specify the procedure for VAE-S to terminate session oriented service with VAE client (e.g. remote vehicle).

6.13.2.4 Session-oriented service establishment

Upon the request from the V2X application specific server or from the VAE client, in order to establish a session-oriented service with one or more VAE clients, the VAE-S shall generate an HTTP POST request according to procedures specified in IETF RFC 2616 [19]. In the HTTP POST request, the VAE-S:

a) shall set the Request-URI to the URI corresponding to the identity of the V2X UE;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-service-info> element in the <VAE-info> root element which:

1) shall include a <VAE-client-id> element set to the identity of the VAE client;

2) shall include a <V2X-service-id> element set to the V2X service ID for which application requirement corresponds to;

3) may include a <session-id> element set to the session identifier to be used for the session-oriented service; and

4) shall include a <reporting-configuration> element indicating which configuration the UE should report (e.g. frequency of reporting, event based); and

d) shall send the HTTP POST request towards the VAE-C according to IETF RFC 2616 [19].

6.13.2.5 Session-oriented service update

Upon the request from the V2X application specific server or from the VAE client, in order to update a session-oriented service with one or more VAE clients, the VAE-S shall generate an HTTP POST request according to procedures specified in IETF RFC 2616 [19]. In the HTTP POST request, the VAE-S:

a) shall set the Request-URI to the URI corresponding to the identity of the V2X UE;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-change-info> element in the <VAE-info> root element which:

1) shall include a <session-id> element set to the session identifier of the session-oriented service that is to be updated; and

2) may include a <V2X-application-QoS-requirements> element indicating the application QoS requirements (reliability, delay, jitter) for the session-oriented service that is to be updated;

3) may include a <network-info> element indicating the change of network; and

4) may include a <server-info> element indicationg the change of server; and

d) shall send the HTTP POST request towards the VAE-C according to IETF RFC 2616 [19].

6.13.2.6 Session-oriented service termination

Upon the request from the V2X application specific server or from the VAE client, in order to terminate a session-oriented service with one or more VAE clients, the VAE-S shall generate an HTTP POST request according to procedures specified in IETF RFC 2616 [19]. In the HTTP POST request, the VAE-S:

a) shall set the Request-URI to the URI corresponding to the identity of the V2X UE;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <session-oriented-termination-info> element in the <VAE-info> root element which shall include a <session-id> element set to the session identifier of the session-oriented service that is to be terminated; and

d) shall send the HTTP POST request towards the VAE-C according to IETF RFC 2616 [19].

6.14 Switching modes of operations for V2V communications procedure

6.14.1 Client procedure

Upon receiving an HTTP POST request message containing:

a) a Content-Type header field set to "application/vnd.3gpp.vae-info+xml"; and

b) an application/vnd.3gpp.vae-info+xml MIME body with an <communication-status-info> element;

the VAE-C shall generate an HTTP 200(OK) response message according to procedures specified in IETF RFC 7231 [19]. In the HTTP 200(OK) response, the VAE-C:

a) shall set the Request-URI to the URI included in the received HTTP response for the V2X service discovery procedure (see clause 6.6);

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <communication-status-info> element included in the <VAE-info> root element which:

1) shall include a <V2X-UE-id> element set to the identity of the V2X UE;

2) shall include a <V2V-communication-mode> element indicating which V2V communication mode supported by the V2X UE;

3) may include a <V2X-service-id> element corresponding to the communication status;

4) may include a <cell-info> element indicating the cell information of which the V2X UE is located; and

5) may include a <communication-link-status-info> element indicating the communication status of the V2X UE; and

d) shall send the HTTP 200(OK) response towards the VAE-S according to IETF RFC 7231 [19].

6.14.2 Server procedure

In oder to provide the assistance for V2V communication mode switching, the VAE-S may have acquired the application requirement from the V2X application specific server and may generate an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-S:

a) shall set the Request-URI to the URI corresponding to the identity of the V2X UE;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <communication-status-info> element in the <VAE-info> root element which:

1) shall include a <V2X-UE-id> element set to the identity of the V2X UE; and

2) may include a <V2X-service-id> element set to the identity of the V2X service being requested; and

d) shall send the HTTP POST request towards the VAE-C according to IETF RFC 7231 [19].

Based on the reception of the network monitoring information from the 3GPP network or the communication status information from the <communication-link-status-info> element of an HTTP 200(OK) response, the VAE-S may generate an HTTP POST request according to procedures specified in IETF RFC 7231 [19]. In the HTTP POST request, the VAE-S:

a) shall set the Request-URI to the URI corresponding to the identity of the V2X UE;

b) shall include a Content-Type header field set to "application/vnd.3gpp.vae-info+xml";

c) shall include an application/vnd.3gpp.vae-info+xml MIME body with a <V2V-communication-assistance-info> element in the <VAE-info> root element which:

1) shall include a <V2X-UE-id> element set to the identity of the V2X UE;

2) may include a <V2X-service-id> element set to the identity of the V2X service corresponding to the recommendation information; and

3) shall include a <V2V-communication-assistance> element indicating the assistance information for V2V communication mode switching to the V2X UE; and

d) shall send the HTTP POST request towards the VAE-C according to IETF RFC 7231 [19].