6 V2X communication

24.3863GPPProtocol aspectsRelease 17Stage 3TSUser Equipment (UE) to V2X control function

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

6.1 V2X communication over PC5

6.1.1 General

This subclause describes the procedures at the UE, and between UEs, for V2X communication over PC5.

The UE shall support requirements for securing V2X communication over PC5 as specified in 3GPP TS 33.185 [20]. The UE shall support a privacy protection for the V2X communication over PC5 subject to regional regulatory requirements and/or operator policy for a V2X application as specified in 3GPP TS 33.185 [20], subclause 6.1.2.4.Both IP based and non-IP based V2X communication over PC5 are supported. For IP based V2X communication, only IPv6 is used. IPv4 is not supported in this release of the present document.

6.1.2 Transmission of V2X communication over PC5

6.1.2.1 Initiation

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 PC5. 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);

d) if the V2X message contains non-IP data, the V2X message family (see subclause 7.1) of data in the V2X message;

e) the V2X message priority; and

f) optionally the ProSe Per-Packet Reliability (PPPR) value.

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 PC5, if the UE is configured with V2X service identifier to V2X frequency mapping rules for V2X communication over PC5 as specified in subclause 5.2.4 and there is one or more V2X frequencies associated with the V2X service identifier of the V2X service for the V2X message in the current the geographical area, pass the one or more V2X frequencies associated with the V2X service identifier of the V2X service for the V2X message to the lower layers. Then, the UE shall proceed as follows:

a) if the following conditions are met:

1) the UE is served by E-UTRAN for V2X communication;

2) the UE intends to use the radio resources (i.e. carrier frequency) provided by an E-UTRAN cell;

3) the registered PLMN is in the list of PLMNs in which the UE is authorized to use V2X communication over PC5 when the UE is served by E-UTRAN for V2X communication as specified in subclause 5.2.4; and

4) the V2X service identifier of the V2X service is included in the list of V2X services authorized for V2X communication over PC5 as specified in subclause 5.2.4 or the UE is configured with a default destination Layer-2 ID for V2X communication over PC5 as specified in subclause 5.2.4;

then the UE shall:

1) request radio resources for V2X communication over PC5 as specified in 3GPP TS 24.334 [4] subclause 10.2.2. When requesting the radio resources for V2X communication over PC5, if:

A) a ProSe Per-Packet Reliability (PPPR) value is received from the upper layers; and

B) one of the following conditions is met:

i) the list of the V2X services authorized for ProSe Per-Packet Reliability (PPPR) is not configured; or

ii) the V2X service identifier of the V2X service for the V2X message and the received ProSe Per-Packet Reliability (PPPR) value are included in an entry of the list of the V2X services authorized for ProSe Per-Packet Reliability (PPPR);

then the UE shall indicate to lower layers the received ProSe Per-Packet Reliability (PPPR) value; and

2) perform transmission of V2X communication over PC5 as specified in subclause 6.1.2.2; and

b) if the following conditions are met:

1) the UE is:

A) not served by E-UTRAN for V2X communication;

B) in limited service state as specified in 3GPP TS 23.122 [9], if the reason for the UE being in limited service state is one of the following;

i) the UE is unable to find a suitable cell in the selected PLMN as specified in 3GPP TS 36.304 [10];

ii) the UE received an ATTACH REJECT message or a TRACKING AREA UPDATE REJECT message or a SERVICE REJECT message with the EMM cause #11 "PLMN not allowed" as specified in 3GPP TS 24.301 [11] or a LOCATION UPDATING REJECT message or a GPRS ATTACH REJECT message or a ROUTING AREA UPDATE REJECT message or SERVICE REJECT message with the EMM cause #11 "PLMN not allowed" as specified in 3GPP TS 24.008 [12]; or

iii) the UE received an ATTACH REJECT message or a TRACKING AREA UPDATE REJECT message or a SERVICE REJECT message with the EMM cause #7 "EPS services not allowed" as specified in 3GPP TS 24.301 [11] or a LOCATION UPDATING REJECT message or a GPRS ATTACH REJECT message or a ROUTING AREA UPDATE REJECT message or a SERVICE REJECT message with the EMM cause #7 "GPRS services not allowed" as specified in 3GPP TS 24.008 [12]; or

C) in limited service state as specified in 3GPP TS 23.122 [9] for reasons other than i), ii) or iii) above, and located in a geographical area for which the UE is provisioned with "non-operator managed" radio parameters as specified in subclause 5.2.4;

2) the UE is authorized to use V2X communication over PC5 when the UE is not served by E-UTRAN for V2X communication as specified in subclause 5.2.4; and

3) the V2X service identifier of the V2X service is included in the list of V2X services authorized for V2X communication over PC5 as specified in subclause 5.2.4 or the UE is configured with a default destination Layer-2 ID for V2X communication over PC5 as specified in subclause 5.2.4;

then the UE shall:

1) select radio resources for V2X communication over PC5 as specified in subclause 6.1.2.3; and

2) perform transmission of V2X communication over PC5 as specified in subclause 6.1.2.2;

else the UE shall not perform transmission of V2X communication over PC5.

If the UE is camped on an E-UTRAN cell indicating that V2X communication over PC5 is supported by the network, but not broadcasting any carrier frequencies and radio resources for V2X communication over PC5 as specified in 3GPP TS 36.331 [23], the UE shall request radio resources for V2X communication over PC5 as specified in 3GPP TS 24.334 [4] subclause 10.2.2.

6.1.2.2 Transmission

The UE shall include the V2X message in a protocol data unit and pass it to the lower layers for transmission along with the following parameters:

a) a Layer-3 protocol data unit type (see 3GPP TS 36.323 [8]) set to:

1) IP packet, if the V2X message contains IP data; or

2) non-IP packet, if the V2X message contains non-IP data;

b) the source Layer-2 ID set to the Layer-2 ID self-assigned by the UE for V2X communication over PC5;

c) the destination Layer-2 ID set to:

1) the destination Layer-2 ID associated with the V2X service identifier of the V2X service in this list of V2X services authorized for V2X communication over PC5 as specified in subclause 5.2.4, if the V2X service identifier of the V2X service is included in the list of V2X services authorized for V2X communication over PC5 as specified in subclause 5.2.4; or

2) the default destination Layer-2 ID configured to the UE for V2X communication over PC5 as specified in subclause 5.2.4, if the V2X service identifier of the V2X service is not included in the list of V2X services authorized for V2X communication over PC5 and the UE is configured with a default destination Layer-2 ID for V2X communication over PC5;

d) if the V2X message contains non-IP data, an indication to set the non-IP type field of the non-IP type PDU to the value corresponding to the V2X message family (see subclause 7.1) used by the V2X service as indicated by upper layers;

e) if the V2X message contains IP data, the source IP address set to the source IP address self-assigned by the UE for V2X communication over PC5;

f) the ProSe Per-Packet Priority set to the value corresponding to the V2X message priority received from upper layers. The mapping of V2X message priority to ProSe Per-Packet Priority is configured on the UE and is out of the scope of this specification;

g) if the UE is configured with PDB (Packet Delay Budget)-to-ProSe Per-Packet Priority mapping rules for V2X communication over PC5 as specified in subclause 5.2.4, the PDB associated with the ProSe Per-Packet Priority as specified in subclause 5.2.4;

h) if:

1) a ProSe Per-Packet Reliability (PPPR) value is received from the upper layers; and

2) one of the following conditions is met:

A) the list of the V2X services authorized for ProSe Per-Packet Reliability (PPPR) is not configured; or

B) the V2X service identifier of the V2X service for the V2X message and the received ProSe Per-Packet Reliability (PPPR) value are included in an entry of the list of the V2X services authorized for ProSe Per-Packet Reliability (PPPR);

then the ProSe Per-Packet Reliability (PPPR) value; and

i) if the UE is configured with V2X service identifier to Tx Profile mapping rules for V2X communication over PC5 as specified in subclause 5.2.4, the Tx Profile associated with the V2X service identifier as specified in subclause 5.2.4.

If the UE has an emergency PDN connection, the UE shall send an indication to the lower layers to prioritize transmission over the emergency PDN connection as compared to transmission of V2X communication over PC5.

6.1.2.3 Procedure for UE to use provisioned radio resources for V2X communication over PC5

When the UE is not served by E-UTRAN for V2X communication, the UE shall select the radio parameters to be used for V2X communication over PC5 as follows:

– if the UE can determine itself located in a geographical area, and the UE is provisioned with radio parameters for the geographical area, the UE shall select the radio parameters associated with that geographical area; or

– in all other cases, the UE shall not initiate V2X communication over PC5.

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, e.g. Global Navigation Satellite System (GNSS). The UE shall not consider user provided location as a valid input to locate itself in a specific geographical area.

If the UE intends to use "non-operator managed" radio parameters as specified in subclause 5.2.4, the UE shall initiate V2X communication over PC5 with the selected radio parameters.

If the UE intends to use "operator managed" radio parameters as specified in subclause 5.2.4, before initiating V2X communication over PC5, the UE shall check with lower layers whether the selected radio parameters can be used in the current location without causing interference to other cells as specified in 3GPP TS 36.331 [22], and:

– if the lower layers indicate that the usage would not cause any interference, the UE shall initiate V2X communication over PC5; or

NOTE: If the lower layers find that there exists a cell operating the provisioned radio resources (i.e., carrier frequency), and the cell belongs to the registered PLMN or a PLMN equivalent to the registered PLMN, and the UE is authorized for V2X communication over PC5 in this PLMN, the UE can use the radio parameters indicated by the cell as specified in 3GPP TS 36.331 [22].

– else if the lower layers report that one or more PLMNs operate in the provisioned radio resources (i.e. carrier frequency) then:

a) if the following conditions are met:

1) none of the PLMNs reported by the lower layers is the registered PLMN or equivalent to the registered PLMN;

2) at least one of the PLMNs reported by the lower layers is in the list of authorized PLMNs for V2X communication over PC5 and provides radio resources for V2X communication over PC5 as specified in 3GPP TS 36.331 [22]; and

3) the UE does not have an emergency PDN connection;

then the UE shall:

1) if in EMM-IDLE mode, perform PLMN selection triggered by V2X communication over PC5 as specified in 3GPP TS 23.122 [9]; or

2) else if in EMM-CONNECTED mode, either:

i) perform a detach procedure as specified in 3GPP TS 24.301 [11] and then perform PLMN selection triggered by V2X communication over PC5 as specified in 3GPP TS 23.122 [9]; or

ii) not initiate V2X communication over PC5.

Whether the UE performs i) or ii) above is left up to UE implementation; or

b) else the UE shall not initiate V2X communication over PC5.

If the registration to the selected PLMN is successful, the UE shall proceed with the procedure to initiate V2X communication over PC5 as specified in subclause 6.1.2.1.

If the UE is performing V2X communication over PC5 using radio parameters associated with a geographical area and moves out of that geographical area, the UE shall stop performing V2X communication over PC5 and then:

– if the UE is not served by E-UTRAN for V2X communication or the UE intends to use radio resources for V2X communication over PC5 other than those operated by the serving E-UTRAN cell, the UE shall select appropriate radio parameters for the new geographical area as specified above; or

– if the UE is served by E-UTRAN for V2X communication and intends to use radio resources for V2X communication over PC5 operated by the serving E-UTRAN cell, the UE shall proceed with the procedure to initiate V2X communication over PC5 when served by E-UTRAN for V2X communication.

6.1.2.4 Privacy of V2X transmission over PC5

Upon initiating transmission of V2X communication over PC5, if:

– the V2X service identifier of a V2X service requesting transmission of V2X communication over PC5 is in the list of of V2X services which require privacy for V2X communication over PC5 as specified in subclause 5.2.4; and

– the UE is located in a geographical area in which this V2X service requires privacy for V2X communication over PC5 as specified in subclause 5.2.4, or the UE is not provisioned any geographical areas in which this V2X services requires privacy for V2X communication over PC5,

the UE shall proceed as follows:

– if timer T5000 is not running, start timer T5000;

– upon:

a) getting an indication from upper layers that the application layer identifier has been changed; or

b) timer T5000 expiration,

then:

a) change the value of the source Layer-2 ID self-assigned by the UE for V2X communication over PC5;

b) if the V2X message contains IP data, change the value of the source IP address self-assigned by the UE for V2X communication over PC5;

c) provide an indication to upper layers that the source Layer-2 ID and/or the source IP address are changed; and

d) restart timer T5000; and

– upon stopping transmission of V2X communication over PC5, stop timer T5000.

6.1.3 Reception of V2X communication over PC5

The UE can be configured by upper layers with one or more destination Layer-2 ID(s) for reception of V2X messages over PC5. For each received protocol data unit over PC5, the receiving UE shall check if the destination Layer-2 ID of the received protocol data unit matches one of the configured destination Layer-2 IDs. If yes, the UE shall then check whether the protocol data unit type as defined 3GPP TS 36.323 [8] provided by the lower layers for the received packet is set to IP packet or non-IP packet, and pass the protocol data unit to the corresponding upper layer entity.

6.2 V2X communication over LTE-Uu

6.2.1 General

Procedures for V2X communication over LTE-Uu for V2X services not identified by a V2X service identifier are out of scope of the present version of the present specification. Security procedures specified in 3GPP TS 33.401 [21] for LTE-Uu, and application layer security as defined in other SDOs (e.g. IEEE or ETSI ITS) apply, as stated in 3GPP 3GPP TS 33.185 [20].

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 LTE-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 LTE-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 subclause 7.1) of data in the V2X message.

Upon a request from upper layers to send a V2X message of a V2X service using V2X communication over LTE-Uu:

a) if the registered PLMN of the UE is not in the list of PLMNs in which the UE is authorized to use V2X communication over LTE-Uu as specified in subclause 5.2.5, the UE shall determine that the transmission of V2X communication over LTE-Uu from UE to V2X application server is not authorized and shall not continue with the rest of the steps; and

b) if the V2X service is identified by a V2X service identifier:

1) if:

A) the type of data in the V2X message is non-IP; or

B) the type of data in the V2X message is IP, and the V2X service identifier is not included in the list of V2X service identifiers of the V2X services authorized for V2X communication over LTE-Uu using existing unicast routing as specified in subclause 5.2.5;

then:

A) the UE shall discover the V2X application server address as described in subclause 6.2.6. If the V2X application server address cannot be discovered, the UE shall determine that the transmission of V2X communication over LTE-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 [18]. 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:

i) 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

ii) the UE shall generate one or more TCP message(s) as described in IETF RFC 793 [rfc793]. 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;

2) if the type of data in the V2X message is IP, and the V2X service identifier is included in the list of V2X service identifiers of the V2X services authorized for V2X communication over LTE-Uu using existing unicast routing as specified in subclause 5.2.5, then the UE shall send the V2X message using existing unicast routing.

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

The V2X application server shall be configured with one or more UDP ports, one or more TCP ports for bidirectional transport or both of them, for reception of the V2X communication over LTE-Uu from the UE.

If the V2X application server is configured with a UDP port, the following applies:

a) 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.

b) 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.

c) The V2X application server shall extract a V2X message of a V2X service from a UDP message received on a local IP address and a UDP port configured for the V2X service.

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).

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

The V2X application server shall be configured with a multicast IP address and one or more UDP ports for transport of the V2X communication over LTE-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 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 for V2X messages of different V2X message families.

In order to transport a V2X message of a V2X service identified by a V2X service identifier via an MBMS bearer, the V2X application server shall generate a UDP message. In the UDP message, 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 UDP port to the configured multicast 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 BM-SC for transport via the MBMS bearer.

6.2.5 Reception of V2X communication over LTE-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 LTE-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 subclause 7.1) of data in the V2X message to be received.

Upon a request from upper layers to receive a V2X message of a V2X service using V2X communication over LTE-Uu:

a) if the registered PLMN of the UE is not in the list of PLMNs in which the UE is authorized to use V2X communication over LTE-Uu as specified in subclause 5.2.5, the UE shall determine that the transmission of V2X communication over LTE-Uu Uu from V2X application server to UE is not authorized and shall not continue with the rest of the steps; and

b) if the V2X service is identified by a V2X service identifier:

1) the UE shall discover one or more V2X MBMS configuration(s) for receiving V2X communication over LTE-Uu using MBMS as described in subclause 6.2.7;2) if the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS is discovered:

A) if the type of data is IP, the UE shall listen for a UDP packet:

i) with the destination IP address set to the IP address indicated in the "c=" line applicable for the "m=" line with the application/vnd.3gpp.v2x media type with the type parameter indicating IP in the SDP body of the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS; and

ii) with the destination UDP port set to the port indicated in the "m=" line with the application/vnd.3gpp.v2x media type with the type parameter indicating IP in the SDP body of the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS;

received via an MBMS bearer corresponding to the TMGI, the list of SAIs and the frequency of the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS. If several V2X MBMS configurations for receiving V2X communication over LTE-Uu using MBMS were discovered, the UE shall perform this action once per each discovered V2X MBMS configurations for receiving V2X communication over LTE-Uu using MBMS;

B) if the type of data is non-IP, the UE shall listen for a UDP packet:

i) with the destination IP address set to the IP address indicated in the "c=" line applicable for the "m=" line with the application/vnd.3gpp.v2x media type with:

– the type parameter indicating non-IP; and

– the v2x-message-family parameter indicating the V2X message family;

in the SDP body of the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS; and

ii) with the destination UDP port set to the port indicated in the "m=" line with the application/vnd.3gpp.v2x media type with:

– the type parameter indicating non-IP; and

– the v2x-message-family parameter indicating the V2X message family;

in the SDP body of the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS;

C) the UE shall extract the V2X message from the data octets field of the received UDP message as described in IETF RFC 768 [18] and pass the V2X message to upper layers. ; ands

3) if the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS is not discovered:

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

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

i) 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

6.2.6 V2X application server discovery

6.2.6.1 General

Before initiating V2X communication over LTE-Uu, the UE needs to discover the V2X application server to which the V2X messages shall be sent. The UE shall proceed as follows, in priority order:

a) if the serving PLMN is associated with a V2X AS MBMS configuration for receiving V2X application server information using MBMS in the configuration parameters for V2X communication over LTE-Uu provisioned to the UE as specified in subclause 5.2.5, the UE shall perform the procedure in subclause 6.2.6.2 to discover the V2X application server;

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 IP address and a UDP port or TCP port for bidirectional transport in the list of V2X services authorized for V2X communication over LTE-Uu for the serving PLMN and the geographical area in which the UE is located as specified in subclause 5.2.5, the UE shall use the IP address and the UDP or TCP port for V2X communication over LTE-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 FQDN and a UDP port or a TCP for bidirectional transport in the list of V2X services authorized for V2X communication over LTE-Uu for the serving PLMN and the geographical area in which the UE is located as specified in subclause 5.2.5, the UE shall perform DNS lookup as specified in IETF RFC 1035 [13], then use the resulting IP address and the configured UDP or TCP port for V2X communication over LTE-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 IP address and a UDP port or a TCP port for bidirectional transport in the list of V2X services authorized for V2X communication over LTE-Uu for the serving PLMN as specified in subclause 5.2.5, the UE shall use the IP address and the UDP or TCP port for V2X communication over LTE-Uu;

e) 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 or a TCP port for bidirectional transport in the list of V2X services authorized for V2X communication over LTE-Uu for the serving PLMN as specified in subclause 5.2.5, the UE shall perform DNS lookup as specified in IETF RFC 1035 [13], then use the resulting IP address and the configured UDP or TCP port for V2X communication over LTE-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 subclause 5.2.5 is configured and contains an IP address and a UDP port 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 LTE-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, the geographical area in which the UE is located and the IP type of data as specified in subclause 5.2.5 is configured and contains an FQDN and a UDP port or a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [13], and shall use the resulting IP address and the UDP or TCP port for V2X communication over LTE-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 the serving PLMN and the IP type of data as specified in subclause 5.2.5 is configured and contains an IP address and a UDP port or a TCP port for bidirectional transport, then the UE shall use the IP address and the UDP or the TCP port for V2X communication over LTE-Uu;

i) 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 subclause 5.2.5 is configured and contains an FQDN and a UDP port or a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [13], and shall use the resulting IP address and the UDP port or TCP port for V2X communication over LTE-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 subclause 5.2.5 is configured and contains an IP address and a UDP port 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 LTE-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, the geographical area in which the UE is located and the V2X message family of the non-IP data as specified in subclause 5.2.5 is configured and contains an FQDN and a UDP port or a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [13], and shall use the resulting IP address and the UDP or TCP port for V2X communication over LTE-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 subclause 5.2.5 is configured and contains an IP address and a UDP port 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 LTE-Uu;

m) 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 subclause 5.2.5 is configured and contains an FQDN and a UDP port or a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [13], and shall use the resulting IP address and the UDP or TCP port for V2X communication over LTE-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 IP address for the serving PLMN and the geographical area in which the UE is located as specified in subclause 5.2.5, the UE shall use this IP address for V2X communication over LTE-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 FQDN for the serving PLMN and the geographical area in which the UE is located as specified in subclause 5.2.5, the UE shall perform DNS lookup as specified in IETF RFC 1035 [13], then use the resulting IP address for V2X communication over LTE-Uu;

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 IP address for the serving PLMN as specified in subclause 5.2.5, the UE shall use this IP address for V2X communication over LTE-Uu; and

q) 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 subclause 5.2.5, the UE shall perform DNS lookup as specified in IETF RFC 1035 [13], then use the resulting IP address for V2X communication over LTE-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 TCP port for bidirectional transport in the list of V2X services authorized for V2X communication over LTE-Uu for the serving PLMN and the geographical area in which the UE is located as specified in subclause 5.2.5, the UE shall use this IP address and the TCP port for V2X communication over LTE-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 TCP port for bidirectional transport in the list of V2X services authorized for V2X communication over LTE-Uu for the serving PLMN and the geographical area in which the UE is located as specified in subclause 5.2.5, the UE shall perform DNS lookup as specified in IETF RFC 1035 [13], then use the resulting IP address and the TCP port for V2X communication over LTE-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 TCP port for bidirectional transport in the list of V2X services authorized for V2X communication over LTE-Uu for the serving PLMN as specified in subclause 5.2.5, the UE shall use this IP address and the TCP port for V2X communication over LTE-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 TCP port for bidirectional transport in the list of V2X services authorized for V2X communication over LTE-Uu for the serving PLMN as specified in subclause 5.2.5, the UE shall perform DNS lookup as specified in IETF RFC 1035 [13], then use the resulting IP address and the TCP port for V2X communication over LTE-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 subclause 5.2.5 is configured and contains an IP address and a TCP port for bidirectional transport, then the UE shall use the IP address and the TCP port for V2X communication over LTE-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 subclause 5.2.5 is configured and contains an FQDN and a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [13], and shall use the resulting IP address and the TCP port for V2X communication over LTE-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 subclause 5.2.5 is configured and contains an IP address and a TCP port for bidirectional transport, then the UE shall use the IP address and the TCP port for V2X communication over LTE-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 subclause 5.2.5 is configured and contains an FQDN and a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [13], and shall use the resulting IP address and the TCP port for V2X communication over LTE-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 subclause 5.2.5 is configured and contains an IP address and a TCP port for bidirectional transport, then the UE shall use the IP address and the TCP port for V2X communication over LTE-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 subclause 5.2.5 is configured and contains an FQDN and a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [13], and shall use the resulting IP address and the TCP port for V2X communication over LTE-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 subclause 5.2.5 is configured and contains an IP address and a TCP port for bidirectional transport, then the UE shall use the IP address and the TCP port for V2X communication over LTE-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 subclause 5.2.5 is configured and contains an FQDN and a TCP port for bidirectional transport, then the UE shall perform DNS lookup of the FQDN as specified in IETF RFC 1035 [13], and shall use the resulting IP address and the TCP port for V2X communication over LTE-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.

6.2.6.2 V2X application server discovery using MBMS

6.2.6.2.1 General

The purpose of the V2X application server discovery using MBMS procedure is to allow the UE to receive the V2X application server information over MBMS bearers.

The UE shall only initiate the V2X application server discovery using MBMS procedure if:

a) the UE is authorized for V2X communication over LTE-Uu in the serving PLMN as specified in subclause 5; and

b) the serving PLMN is associated with a V2X AS MBMS configuration for receiving V2X application server information using MBMS in the configuration parameters for V2X communication over LTE-Uu provisioned to the UE as specified in subclause 5.2.5.

The UE should use the V2X application server information received over MBMS bearers for transmission of V2X communication over LTE-Uu using unicast only when the UE is registered in the PLMN from which this V2X application server information was received.

6.2.6.2.2 Procedure for V2X application server discovery using MBMS

The UE shall proceed as follows:

a) the UE shall start listening to the MBMS bearer corresponding to the TMGI, list of SAIs and frequency included in the V2X AS MBMS configuration associated with the serving PLMN in the configuration parameters for V2X communication over LTE-Uu provisioned to the UE as specified in subclause 5.2.5

b) the UE shall use the IP multicast address and port included in the V2X AS MBMS configuration associated with the serving PLMN in the configuration parameters for V2X communication over LTE-Uu provisioned to the UE as specified in subclause 5.2.5 to receive the V2X local service information. The V2X local service information is encoded as specified in subclause 7.4; and

NOTE: The UE can be in MBMS receive only mode for obtaining the V2X application server information.

c) If the V2X service identifier of the V2X service requesting V2X communication over LTE-Uu maps to a V2X application server FQDN in the V2X application server information obtained at step 2, the UE shall perform DNS lookup as specified in IETF RFC 1035 [13] to resolve the IP address(es) of the V2X application server.

6.2.7 V2X MBMS parameter discovery

Before receiving a V2X communication over LTE-Uu using MBMS bearer, the UE needs to discover the V2X MBMS parameters via which the V2X communication is to be received.

The UE shall proceed as follows, in priority order:

a) if the V2X message to be received is of IP type of data, the V2X service of the V2X message to be received is identified by a V2X service identifier, and this V2X service identifier is associated with a V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS in the list of V2X services authorized for V2X communication over LTE-Uu for the registered PLMN of the UE and the SDP body of the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS contains a "m=" line of the application/vnd.3gpp.v2x media type with the type parameter indicating IP, the UE shall use the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS. If several such V2X MBMS configurations are configured, the UE shall use all such V2X MBMS configurations for receiving V2X communication over LTE-Uu using MBMS;

b) else if the V2X message to be received is of non-IP type of data, the V2X message to be received is of V2X message family, the V2X service of the V2X message to be received is identified by a V2X service identifier, and this V2X service identifier is associated with a V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS in the list of V2X services authorized for V2X communication over LTE-Uu for the registered PLMN of the UE and the SDP body of the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS contains a "m=" line of the application/vnd.3gpp.v2x media type with:

1) the type parameter indicating non-IP; and

2) the v2x-message-family parameter indicating the V2X message family;

the UE shall use the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS. If several such V2X MBMS configurations are configured, the UE shall use all such V2X MBMS configurations for receiving V2X communication over LTE-Uu using MBMS;

c) else if the V2X message to be received is of IP type of data, the V2X service of the V2X message to be received is identified by a V2X service identifier, and the default V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS as specified in subclause 5.2.5 is configured and the SDP body of the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS contains a "m=" line of the application/vnd.3gpp.v2x media type with the type parameter indicating IP, the UE shall use the default V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS. If several such V2X MBMS configurations are configured, the UE shall use all such V2X MBMS configurations for receiving V2X communication over LTE-Uu using MBMS;

d) else if the V2X message to be received is of non-IP type of data, the V2X message to be received is of V2X message family, the V2X service of the V2X message to be received is identified by a V2X service identifier, and the default V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS as specified in subclause 5.2.5 is configured and the SDP body of the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS contains a "m=" line of the application/vnd.3gpp.v2x media type with:

1) the type parameter indicating non-IP; and

2) the v2x-message-family parameter indicating the V2X message family;

the UE shall use the default V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS. If several such V2X MBMS configurations are configured, the UE shall use all such V2X MBMS configurations for receiving V2X communication over LTE-Uu using MBMS; and

e) else if the V2X service of the V2X message to be received is not identified by a V2X service identifier, and the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS as specified in subclause 5.2.5 is configured, the UE shall use the V2X MBMS configuration for receiving V2X communication over LTE-Uu using MBMS. If several such V2X MBMS configurations are configured, the UE shall use all such V2X MBMS configurations for receiving V2X communication over LTE-Uu using MBMS.