6.2 V2X communication over Uu

24.5873GPPRelease 18Stage 3TSVehicle-to-Everything (V2X) services in 5G System (5GS)

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

6.2.1 General

This clause describes the procedures at the UE and the V2X application server, for V2X communication over Uu.

There are no additional security or privacy procedures of V2X communication over Uu beyond those specified in 3GPP TS 33.501 [21] for Uu connectivity with 5GCN.

Both IP based and non-IP based V2X communication over Uu are supported.

V2X messages carried over Uu are sent or received over unicast only in this release of the specification. Furthermore, V2X messages are carried over Uu using user data over user plane. For this, the UE first performs the UE-requested PDU session establishment procedure to establish user-plane resouces as specified in 3GPP TS 24.501 [6].

Procedures for V2X communication over Uu for V2X services not identified by a V2X service identifier are out of scope of the present version of the present specification.

NOTE: The upper layers are responsible for re-assembly of V2X messages and that is out of scope of 3GPP.

6.2.2 Transmission of V2X communication over Uu from UE to V2X application server

The upper layers can request the UE to send a V2X message of a V2X service identified by a V2X service identifier using V2X communication over Uu. The request from the upper layers includes:

a) the V2X message;

b) the V2X service identifier of the V2X service for the V2X message;

c) the type of data in the V2X message (IP or non-IP); and

d) if the V2X message contains non-IP data, the V2X message family (see clause 9.2) of data in the V2X message.

Upon a request from upper layers to send a V2X message of a V2X service identified by a V2X service identifier using V2X communication over Uu:

a) if the registered PLMN of the UE is not in the list of PLMNs in which the UE is configured to use V2X communication over Uu as specified in clause 5.2.4, the UE shall determine that the transmission of V2X communication over Uu from UE to V2X application server is not configured and shall not continue with the rest of the steps; and

b) if the V2X service identifier is included in the list of V2X service identifier to PDU session parameters mapping rules specified in clause 5.2.4;

then:

1) the UE shall determine the mapping rule in the list of V2X service identifier to PDU session parameters mapping rules specified in clause 5.2.4, such that the mapping rule contains the V2X service identifier provided by upper layers;

2) the UE shall consider the PDU session type, the SSC mode (if indicated in determined mapping rule), an S-NSSAI (if indicated in determined mapping rule) and a DNN (if indicated in determined mapping rule) indicated in the determined mapping rule as the UE local configuration and request information of the PDU session via which to send a PDU according to 3GPP TS 24.526 [22]. The UE shall use the transport layer protocol, if indicated in the determined mapping rule, to transport the V2X message;

3) if the PDU session is of "IPv4", "IPv6" or "IPv4v6" PDU session type:

i) if the V2X service identifier is included in the list of V2X service identifier to V2X application server address mapping rules as specified in clause 5.2.4, then:

A) the UE shall discover the V2X application server address for uplink transport as described in clause 6.2.6. If the V2X application server address cannot be discovered, the UE shall determine that the transmission of V2X communication over Uu from UE to V2X application server is not possible and shall not continue with the rest of the steps;

B) if UDP is to be used for the determined V2X application server address, the UE shall generate a UDP message as described in IETF RFC 768 [14]. In the UDP message, the UE shall include the V2X message provided by upper layers in the data octets field. The UE shall send the UDP message to the determined V2X application server address; and

C) if TCP is to be used for the determined V2X application server address:

1) if a TCP connection with the determined V2X application server address is not established yet, the UE shall establish a TCP connection with the determined V2X application server address; and

2) the UE shall generate one or more TCP message(s) as described in IETF RFC 793 [25]. In the one or more TCP message(s), the UE shall include the V2X message provided by upper layers in the data octets filed. The UE shall send the one or more TCP message(s) to the determined V2X application server address via the TCP connection; and

4) if the PDU session is of "Unstructured" PDU session type and the type of data in the V2X message is non-IP, the UE shall generate a UDP message as described in IETF RFC 768 [14]. In the UDP message, the UE shall encapsulate the V2X message provided by upper layers in the data octets field. The UE shall send the UDP message to the determined V2X application server address.

6.2.3 Reception of V2X communication over Uu from UE to V2X application server

If the V2X application server is configured with one or more UDP ports for uplink transport or one or more TCP ports for bidirectional transport, of V2X message(s) of V2X service(s) identified by V2X service identifier(s) using the V2X communication over Uu as specified in clause 6.2.7:

1) if the V2X application server is configured with a UDP port for uplink transport, the V2X application server shall extract a V2X message of the V2X service from a UDP message received on a local IP address and a UDP port; and

2) if the V2X application server is configured with a TCP port for bidirectional transport, the V2X application server shall listen for incoming TCP connection(s) on a local IP address and the TCP port, shall accept the incoming TCP connection(s), shall receive one or more TCP message(s)via the accepted TCP connection(s) and shall extract a V2X message of the V2X service from the received one or more TCP message(s).

If the V2X application server is configured to handle data of "Unstructured" PDU Session type for transport of V2X message(s) of V2X service(s) identified by V2X service identifier(s) using V2X communication over Uu as specified in clause 6.2.7, the V2X application server shall receive one or more UDP message(s) as data of a point-to-point tunnel established over N6 and shall extract a V2X message and a V2X message family (if the V2X message is non-IP based) from the received UDP message.

6.2.4 Transmission of V2X communication over Uu from V2X application server to UE

The V2X application server shall be configured with UDP port(s), TCP port(s) or any combination of them for transport of the V2X communication over Uu to the UE.

If the V2X application server supports V2X messages of IP type of data and of non-IP type of data, then the V2X application server shall be configured with different UDP ports or TCP ports for V2X messages of different types of data.

If the V2X application server supports V2X messages of several V2X message families, then the V2X application server shall be configured with different UDP ports or TCP ports for V2X messages of different V2X message families.

If the V2X application server determines to use UDP for transmission of the V2X message identified by a V2X service identifier, the V2X application server shall generate a UDP message. If the V2X message is of "Unstructured" PDU Session type, then the V2X application server shall encapsulate the V2X message into IP type data. In the UDP message, the V2X application server:

a) shall set data octets field to the V2X message if the V2X message is of IP type;

a) shall set data octets field to the encapsulated IP type data if the V2X message is of "Unstructured" PDU Session type; and

c) shall set the destination IP address and the destination UDP port to the UE’s IP address and the configured UDP port associated the type of data of the V2X message and the V2X message family of the data of the V2X message (in case of non-IP).

The V2X application server sends the UDP message as the user plane data to the UE.

If the V2X application server determines to use TCP for transmission of the V2X message identified by a V2X service identifier, the V2X application server establishes a TCP connection with the UE if no TCP connection exists, then the V2X application server shall generate one or more TCP message(s). In the one or more TCP message(s), the V2X application server:

a) shall set data octets field to the V2X message; and

b) shall set the destination IP address and the destination TCP port to the UE’s IP address and the configured TCP port associated the type of data of the V2X message and the V2X message family of the data of the V2X message (in case of non-IP).

The V2X application server sends the one or more TCP message(s) as the user plane data to the UE.

6.2.5 Reception of V2X communication over Uu from V2X application server to UE

The upper layers can request the UE to receive a V2X message of a V2X service identified by a V2X service identifier using V2X communication over Uu. The request from the upper layers includes:

a) the V2X service identifier of the V2X service for the V2X message to be received;

b) the type of data in the V2X message to be received (IP or non-IP); and

c) if the V2X message to be received contains non-IP data, the V2X message family (see clause 9.2) of data in the V2X message to be received.

Upon a request from upper layers to receive a V2X message of a V2X service identified by a V2X service identifier using V2X communication over Uu:

a) if the registered PLMN of the UE is not in the list of PLMNs in which the UE is configured to use V2X communication over Uu as specified in clause 5.2.4, the UE shall determine that the transmission of V2X communication over Uu from V2X application server to UE is not configured and shall not continue with the rest of the steps; and

b) if the V2X service identifier is included in the list of V2X service identifier to PDU session parameters mapping rules specified in clause 5.2.4;

then:

2) the UE shall establish a PDU session with the PDU session type, the SSC mode (if indicated in determined mapping rule), an S-NSSAI (if indicated in determined mapping rule) and a DNN (if indicated in determined mapping rule) indicated in the determined mapping rule, if such PDU session does not exist yet. The UE shall use the transport layer protocol, if indicated in the determined mapping rule, to receive the V2X message;

3) if the PDU session is of "IPv4", "IPv6" or "IPv4v6" PDU session type:

i) if the V2X service identifier is included in the list of V2X service identifier to V2X application server address mapping rules as specified in clause 5.2.4, then:

A) the UE shall discover the V2X application server address for downlink transport as described in clause 6.2.6. If the V2X application server address cannot be discovered, the UE shall determine that the transmission of V2X communication over Uu from V2X application server to UE is not possible and shall not continue with the rest of the steps. If the V2X service identifier is not included in the list of V2X service identifier to V2X application server address mapping rules as specified in clause 5.2.4, the UE shall continue with the rest of the steps; and

B) if UDP is to be used for the determined V2X application server address:

1) the UE shall select the UDP port for downlink transport based on configuration parameters for V2X communication as defined in clause 5.2.4; and

2) the UE shall listen for UDP packets over the determined UDP port, and provide the UDP packets to the upper layers if received; and

C) if TCP is to be used for the determined V2X application server address:

1) if a TCP connection with the determined V2X application server address is not established yet, the UE shall establish a TCP connection with the determined V2X application server address; and

2) the UE shall listen for TCP packets over the established TCP connection, and provide the TCP packets to the upper layers if received; and

4) if the PDU session is of "Unstructured" PDU session type and the type of data in the V2X message is non-IP, the UE shall proceed as UDP is to be used for the determined V2X application server address with the exeption that the V2X message is encapsulated as IP type data packets.

6.2.6 V2X application server discovery

Before initiating V2X communication over Uu, the UE needs to discover the V2X application server to which the V2X messages shall be sent or received.

To discover the V2X application server address for uplink transport, the UE shall proceed as follows, in priority order:

a) if the V2X service of the V2X message is identified by a V2X service identifier and this V2X service identifier is associated with a V2X application server IP address and a UDP port for uplink transport or a TCP port for bidirectional transport in the list of V2X service identifier to V2X application server address mapping rules for the serving PLMN and the geographical area in which the UE is located as specified in clause 5.2.4, the UE shall use this IP address and the UDP or TCP port for V2X communication over Uu;

b) else if the V2X service of the V2X message is identified by a V2X service identifier and this V2X service identifier is associated with a V2X application server FQDN and a UDP port for uplink transport or a TCP port for bidirectional transport in the list of V2X service identifier to V2X application server address mapping rules for the serving PLMN and the geographical area in which the UE is located as specified in clause 5.2.4, the UE shall perform DNS lookup as specified in IETF RFC 1035 [19], then use the resulting IP address and the UDP or TCP port for V2X communication over Uu;

c) else if the V2X service of the V2X message is identified by a V2X service identifier and this V2X service identifier is associated with a V2X application server IP address and a UDP port for uplink transport or a TCP port for bidirectional transport in the list of V2X service identifier to V2X application server address mapping rules for the serving PLMN as specified in clause 5.2.4, the UE shall use this IP address and the UDP or TCP port for V2X communication over Uu;

d) else if the V2X service of the V2X message is identified by a V2X service identifier and this V2X service identifier is associated with a V2X application server FQDN and a UDP port for uplink transport or a TCP port for bidirectional transport in the list of V2X service identifier to V2X application server address mapping rules for the serving PLMN as specified inclause 5.2.4, the UE shall perform DNS lookup as specified in IETF RFC 1035 [19], then use the resulting IP address and the UDP or TCP port for V2X communication over Uu;

e) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains IP data, and the default V2X application server address applicable for the serving PLMN, the geographical area in which the UE is located and the IP type of data as specified in clause 5.2.4 is configured and contains an IP address and a UDP port for uplink transport or a TCP port for bidirectional transport, then the UE shall use the IP address and the UDP or TCP port for V2X communication over Uu;

f) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains IP data, and the default V2X application server address applicable for the serving PLMN, the geographical area in which the UE is located and the IP type of data as specified in clause 5.2.4 is configured and contains an FQDN and a UDP port for uplink transport or a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [19], and shall use the resulting IP address and the UDP or TCP port for V2X communication over Uu;

g) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains IP data, and the default V2X application server address applicable for the serving PLMN and the IP type of data as specified in clause 5.2.4 is configured and contains an IP address and a UDP port for uplink transport or a TCP port for bidirectional transport, then the UE shall use the IP address and the UDP or TCP port for V2X communication over Uu;

h) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains IP data, and the default V2X application server address applicable for the serving PLMN and the IP type of data as specified in clause 5.2.4 is configured and contains an FQDN and a UDP port for uplink transport or a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [19], and shall use the resulting IP address and the UDP or TCP port for V2X communication over Uu;

i) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains non-IP data, and the default V2X application server address applicable for the serving PLMN, the geographical area in which the UE is located and the V2X message family of the non-IP data as specified in clause 5.2.4 is configured and contains an IP address and a UDP port for uplink transport or a TCP port for bidirectional transport, then the UE shall use the IP address and the UDP or TCP port for V2X communication over Uu;

j) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains non-IP data, and the default V2X application server address applicable for the serving PLMN, the geographical area in which the UE is located and the V2X message family of the non-IP data as specified in clause 5.2.4 is configured and contains an FQDN and a UDP port for uplink transport or a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [19], and shall use the resulting IP address and the UDP or TCP port for V2X communication over Uu;

k) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains non-IP data, and the default V2X application server address applicable for the serving PLMN and the V2X message family of the non-IP data as specified in clause 5.2.4 is configured and contains an IP address and a UDP port for uplink transport or a TCP port for bidirectional transport, then the UE shall use the IP address and the UDP or TCP port for V2X communication over Uu;

l) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains non-IP data, and the default V2X application server address applicable for the serving PLMN and the V2X message family of the non-IP data as specified in clause 5.2.4 is configured and contains an FQDN and a UDP port for uplink transport or a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [19], and shall use the resulting IP address and the UDP or TCP port for V2X communication over Uu;

m) else if the V2X service of the V2X message is not identified by a V2X service identifier and the UE is configured with a V2X application server IP address for the serving PLMN and the geographical area in which the UE is located as specified in clause 5.2.4, the UE shall use this IP address for V2X communication over Uu;

n) else if the V2X service of the V2X message is not identified by a V2X service identifier and the UE is configured with a V2X application server FQDN for the serving PLMN and the geographical area in which the UE is located as specified in clause 5.2.4, the UE shall perform DNS lookup as specified in IETF RFC 1035 [19], then use the resulting IP address for V2X communication over Uu;

o) else if the V2X service of the V2X message is not identified by a V2X service identifier and the UE is configured with a V2X application server IP address for the serving PLMN as specified in clause 5.2.4, the UE shall use this IP address for V2X communication over Uu; and

p) else if the V2X service of the V2X message is not identified by a V2X service identifier and the UE is configured with a V2X application server FQDN for the serving PLMN as specified in clause 5.2.4, the UE shall perform DNS lookup as specified in IETF RFC 1035 [19], then use the resulting IP address for V2X communication over Uu.

NOTE: It is out of scope of the present specification to define how the UE can locate itself in a specific geographical area. When the UE is in coverage of a 3GPP RAT it can for example use information derived from the serving PLMN. When the UE is not in coverage of a 3GPP RAT it can use other techniques.

To discover the V2X application server address for downlink transport, the UE shall proceed as follows, in priority order:

a) if the V2X service of the V2X message is identified by a V2X service identifier and this V2X service identifier is associated with a V2X application server IP address and a UDP port for downlink transport or a TCP port for bidirectional transport in the list of V2X service identifier to V2X application server address mapping rules for the serving PLMN and the geographical area in which the UE is located as specified in clause 5.2.4, the UE shall use this IP address and the UDP or TCP port for V2X communication over Uu;

b) else if the V2X service of the V2X message is identified by a V2X service identifier and this V2X service identifier is associated with a V2X application server FQDN and a UDP port for downlink transport or a TCP port for bidirectional transport in the list of V2X service identifier to V2X application server address mapping rules for the serving PLMN and the geographical area in which the UE is located as specified in clause 5.2.4, the UE shall perform DNS lookup as specified in IETF RFC 1035 [19], then use the resulting IP address and the UDP or TCP port for V2X communication over Uu;

c) else if the V2X service of the V2X message is identified by a V2X service identifier and this V2X service identifier is associated with a V2X application server IP address and a UDP port for downlink transport or a TCP port for bidirectional transport in the list of V2X service identifier to V2X application server address mapping rules for the serving PLMN as specified in clause 5.2.4, the UE shall use this IP address and the UDP or TCP port for V2X communication over Uu;

d) else if the V2X service of the V2X message is identified by a V2X service identifier and this V2X service identifier is associated with a V2X application server FQDN and a UDP port for downlink transport or a TCP port for bidirectional transport in the list of V2X service identifier to V2X application server address mapping rules for the serving PLMN as specified in clause 5.2.4, the UE shall perform DNS lookup as specified in IETF RFC 1035 [19], then use the resulting IP address and the UDP or TCP port for V2X communication over Uu;

e) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains IP data, and the default V2X application server address applicable for the serving PLMN, the geographical area in which the UE is located and the IP type of data as specified in clause 5.2.4 is configured and contains an IP address and a UDP port for downlink transport or a TCP port for bidirectional transport, then the UE shall use the IP address and the UDP or TCP port for V2X communication over Uu;

f) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains IP data, and the default V2X application server address applicable for the serving PLMN, the geographical area in which the UE is located and the IP type of data as specified in clause 5.2.4 is configured and contains an FQDN and a UDP port for downlink transport or a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [19], and shall use the resulting IP address and the UDP or TCP port for V2X communication over Uu;

g) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains IP data, and the default V2X application server address applicable for the the serving PLMN and the IP type of data as specified in clause 5.2.4 is configured and contains an IP address and a UDP port for downlink transport or a TCP port for bidirectional transport, then the UE shall use the IP address and the UDP or TCP port for V2X communication over Uu;

h) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains IP data, and the default V2X application server address applicable for the serving PLMN and the IP type of data as specified in clause 5.2.4 is configured and contains an FQDN and a UDP port for downlink transport or a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [19], and shall use the resulting IP address and the UDP or TCP port for V2X communication over Uu;

i) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains non-IP data, and the default V2X application server address applicable for the serving PLMN, the geographical area in which the UE is located and the V2X message family of the non-IP data as specified in clause 5.2.4 is configured and contains an IP address and a UDP port for downlink transport or a TCP port for bidirectional transport, then the UE shall use the IP address and the UDP or TCP port for V2X communication over Uu;

j) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains non-IP data, and the default V2X application server address applicable for the serving PLMN, the geographical area in which the UE is located and the V2X message family of the non-IP data as specified in clause 5.2.4 is configured and contains an FQDN and a UDP port for downlink transport or a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [19], and shall use the resulting IP address and the UDP or TCP port for V2X communication over Uu;

k) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains non-IP data, and the default V2X application server address applicable for the serving PLMN and the V2X message family of the non-IP data as specified in clause 5.2.4 is configured and contains an IP address and a UDP port for downlink transport or a TCP port for bidirectional transport, then the UE shall use the IP address and the UDP or TCP port for V2X communication over Uu; and

l) else if the V2X service of the V2X message is identified by a V2X service identifier, the V2X message contains non-IP data, and the default V2X application server address applicable for the serving PLMN and the V2X message family of the non-IP data as specified in clause 5.2.4 is configured and contains an FQDN and a UDP port for downlink transport or a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [19], and shall use the resulting IP address and the UDP or TCP port for V2X communication over Uu.

If multiple V2X application servers are discovered, the V2X application server to be used is selected by the V2X application layer.

The UE shall perform V2X application server discovery again when the UE changes its registered PLMN.

If the V2X application server used by the UE is associated with a particular geographical area, the UE shall perform V2X application server discovery again when the UE moves out of that geographical area.

6.2.7 V2X application server configuration

For transport of V2X message(s) of V2X service(s) identified by V2X service identifier(s) using V2X communication over Uu, the V2X application server shall be configured:

a) with one or more UDP ports for uplink transport;

b) with one or more UDP ports for downlink transport;

c) with one or more TCP ports for bidirectional transport;

d) to handle data of "Unstructured" PDU Session type; or

e) any combination of the above.

If the V2X application server is configured with one or more UDP ports for uplink transport of V2X message(s) of a V2X service(s) identified by V2X service identifier(s) using V2X communication over Uu:

1) if the V2X application server supports V2X messages of IP type of data and of non-IP type of data, then the V2X application server shall be configured with different UDP ports for V2X messages of different types of data; and

2) if the V2X application server supports V2X messages of several V2X message families, then the V2X application server shall be configured with different UDP ports for V2X messages of different V2X message families.