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Content for  TS 23.287  Word version:  17.2.0

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5.4  QoS handling for V2X communicationWord‑p. 25

5.4.1  QoS handling for V2X communication over PC5 reference pointWord‑p. 25

5.4.1.1  QoS modelWord‑p. 25

5.4.1.1.1  General overviewWord‑p. 25
For LTE based PC5, the QoS handling is defined in TS 23.285, based on ProSe Per-Packet Priority (PPPP) and ProSe Per-Packet Reliability (PPPR).
For NR based PC5, a QoS model similar to that defined in TS 23.501 for Uu reference point is used, i.e. based on 5QIs, with additional parameter of Range as described in clause 5.4.2, clause 5.4.3 and clause 5.4.4. For the V2X communication over NR based PC5 reference point, a PC5 QoS Flow is associated with a PC5 QoS Rule and the PC5 QoS parameters as defined in clause 5.4.2. A set of standardized PC5 5QIs (PQI) are defined in clause 5.4.4. The UE may be configured with a set of default PC5 QoS parameters to use for the V2X service types, as defined in clause 5.1.2.1. For NR based unicast, groupcast and broadcast mode communication over PC5, Per-flow QoS model for PC5 QoS management shall be applied. Figure 5.4.1.1.1-1 illustrates an example mapping of Per-flow QoS model for NR PC5. Details of PC5 QoS Rules and PFI related operations are described in clause 5.4.1.1.2 and clause 5.4.1.1.3.
Copy of original 3GPP image for 3GPP TS 23.287, Fig. 5.4.1.1.1-1: Per-Flow PC5 QoS Model for NR PC5
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The following principles apply when the V2X communication is carried over PC5 reference point:
  • Application layer may set the V2X Application Requirements for the V2X communication, using either TS 23.285 defined PPPP and PPPR model or the PQI and Range model as described in clause 5.4.4. Depending on the type of PC5 reference point, i.e. LTE based or NR based, selected for the transmission, the UE may map the application layer provided V2X Application Requirements to the suitable QoS parameters to be passed to the lower layer. The mapping between the two QoS models is defined in clause 5.4.2. For V2X communication over NR based PC5, different V2X packets may require different QoS treatments. In that case, the V2X packets shall be sent from the V2X layer to the Access Stratum layer within PC5 QoS Flows identified by different PFIs.
  • When groupcast mode of V2X communication over NR based PC5 is used, a Range parameter is associated with the QoS parameters for the V2X communication. The Range may be provided by V2X application layer or use a default value mapped from the V2X service type based on configuration as defined in clause 5.1.2.1. The Range indicates the minimum distance that the QoS parameters need to be fulfilled. The Range parameter is passed to AS layer together with the QoS parameters for dynamic control.
  • NR based PC5 supports three communication modes, i.e. broadcast, groupcast, and unicast. The QoS handling of these different modes are described in clause 5.4.1.2 to clause 5.4.1.4.
  • The UE may handle traffic using broadcast, groupcast, and unicast mode communication by taking all their priorities, e.g. indicated by PQIs, into account as described in clause 5.4.3.3.
  • For broadcast and groupcast modes of V2X communication over NR based PC5, standardized PQI values are applied by the UE, as there is no signalling over PC5 reference point for these cases.
  • When network scheduled operation mode is used, the UE-PC5-AMBR for NR based PC5 applies to all types of communication modes, and is used by NG-RAN for capping the UE's NR based PC5 transmission in the resources management. The UE-PC5-AMBR shall be set to the sum of the aggregate maximum bit rate of all types of communication (i.e. unicast, groupcast and broadcast modes) over PC5 reference point.
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5.4.1.1.2  Deriving PC5 QoS parameters and assigning PFI for PC5 QoS FlowWord‑p. 27
The following description applies to for both network scheduled operation mode and UE autonomous resources selection mode.
When a service data packet or request from the V2X application layer is received, the UE determines if there is any existing PC5 QoS Flow matching the service data packet or request, i.e. based on the PC5 QoS Rules for the existing PC5 QoS Flow(s).
If there is no PC5 QoS Flow matching the service data packet or request, the UE derives PC5 QoS parameters defined in clause 5.4.2 as below:
  • If the application layer provides the V2X Application Requirements for the V2X service type (e.g. priority requirement, reliability requirement, delay requirement, range requirement), the V2X layer determines the PC5 QoS parameters based on the V2X Application Requirements;
  • Otherwise, the V2X layer determines the PC5 QoS parameters based on the mapping of the V2X service type to PC5 QoS parameters defined in clause 5.1.2.1.
After deriving the PC5 QoS parameters, the UE performs the following:
  • If there is no existing PC5 QoS Flow that fulfils the derived PC5 QoS parameters:
    • The UE creates a new PC5 QoS Flow for the derived PC5 QoS parameters; and
    • The UE then assigns a PFI and derives PC5 QoS Rule for this PC5 QoS Flow.
  • Otherwise, the UE updates the PC5 Packet Filter Set in the PC5 QoS Rule for such PC5 QoS Flow.
For V2X communication over NR PC5 reference point, the PC5 QoS Flow is the finest granularity of QoS differentiation in the same destination identified by Destination Layer-2 ID. User Plane traffic with the same PFI receives the same traffic forwarding treatment (e.g. scheduling, admission threshold). The PFI is unique within a same destination.
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5.4.1.1.3  Handling of PC5 QoS Flows based on PC5 QoS RulesWord‑p. 27
For each communication mode (e.g. broadcast, groupcast, unicast), the UE maintains the PC5 QoS Context and PC5 QoS Rule(s) for each PC5 QoS Flow identified by a PC5 QoS Flow Identifier (PFI) per destination identified by Destination Layer-2 ID.
The following information is maintained in the V2X layer of the UE:
  • A PC5 QoS Context includes the following information:
    • PFI;
    • PC5 QoS parameters (i.e. PQI and conditionally other parameters such as MFBR/GFBR, Range, etc.) as defined in clause 5.4.2; and
    • the V2X service type(s).
  • One or more PC5 QoS Rule(s). Each PC5 QoS Rule contains the following information:
    • PFI;
    • a PC5 Packet Filter Set as defined in clause 5.4.1.1.4; and
    • a precedence value. The precedence value determines the order in which the PC5 QoS Rules are evaluated. The PC5 QoS Rule with lower precedence value is evaluated before those with the higher precedence values.
When the UE assigns a new PFI for V2X service type, the UE stores it with the corresponding PC5 QoS Context and PC5 QoS Rule(s) for the destination. When the UE releases the PFI, the UE removes the corresponding PC5 QoS Context and PC5 QoS Rule(s) for the destination. For unicast, the Unicast Link Profile defined in clause 5.2.1.4 contains additional information mapped from PFI for unicast operation.
The V2X layer provides information for PC5 QoS operations per destination (e.g. identified by Destination Layer-2 ID) to AS layer for Per-flow QoS model operations as below:
  1. To add a new PC5 QoS Flow or to modify any existing PC5 QoS Flow, the V2X layer provides the following information for the PC5 QoS Flow to AS layer.
    • the PFI;
    • the corresponding PC5 QoS parameters; and
    • source/destination Layer-2 IDs for broadcast and groupcast mode communication, or the PC5 Link Identifier for unicast.
  2. To remove any existing PC5 QoS Flow, the V2X layer provides the following information for the PC5 QoS Flow to AS layer.
    • the PFI; and
    • source/destination Layer-2 IDs for broadcast and groupcast mode communication, or the PC5 Link Identifier for unicast.
In addition, the V2X layer also provides the communication mode (e.g. broadcast, groupcast, unicast) and radio frequencies to the AS layer for the PC5 operation. The radio frequencies are determined based on the V2X service type. The V2X layer ensures that V2X service types associated with different radio frequencies are classified into distinct PC5 QoS Flows.
Figure 5.4.1.1.3-1 illustrated an example of the classification and marking of user plane traffic using the PC5 QoS Rules, and the mapping of PC5 QoS Flows to radio resources at access stratum layer.
Copy of original 3GPP image for 3GPP TS 23.287, Fig. 5.4.1.1.3-1: Handling of PC5 QoS Flows based on PC5 QoS Rules
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As illustrated in Figure 5.4.1.1.3-1, for a given pair of source and destination Layer-2 IDs, there can be multiple radio bearers, each corresponding to a different PC5 QoS level. The AS layer can determine the mapping of multiple PC5 QoS Flows to the same radio bearer based on the information provided. For broadcast and groupcast mode communication, the L2 link goes to all UEs in proximity identified by the destination Layer-2 ID.
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5.4.1.1.4  PC5 Packet Filter SetWord‑p. 29
PC5 Packet Filter Set supports two types of packet filters, i.e. the V2X IP Packet Filter Set and the V2X Packet Filter Set. A PC5 QoS Rule contains either the V2X IP Packet Filter Set or the V2X Packet Filter Set.
The V2X IP Packet Filter Set has the same format as the IP Packet Filter Set defined in clause 5.7.6.2 of TS 23.501.
The V2X Packet Filter Set shall support Packet Filters based on at least any combination of:
  • V2X service type;
  • Source/Destination Layer-2 ID;
  • Application Layer ID (e.g. Station ID).
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5.4.1.2  QoS handling for broadcast mode V2X communication over PC5 reference pointWord‑p. 29

When PC5 broadcast is used for the transmission of V2X service data, the following principles are followed for both network scheduled operation mode and UE autonomous resources selection mode:
  • PC5 QoS parameters defined in clause 5.4.2 are applied.
  • The V2X layer determines the PC5 QoS parameters based on the V2X Application Requirements (if available) or the mapping of the V2X service type to PC5 QoS parameters, as defined in clause 5.4.1.1.2.
  • The V2X layer assigns a PC5 QoS Flow Identifier (PFI) and derives the PC5 QoS Rule for the PC5 QoS Flow, and associates the PC5 QoS parameters to the PFI.
  • The V2X layer provides the PFI and the associated PC5 QoS parameters to AS layer for Per-flow QoS model operations.
  • The V2X layer determines the PFI based on the PC5 QoS Rule for the V2X service data from the V2X application layer, and passes the V2X service data along with PFI to the AS layer for transmission.
When the autonomous resources selection mode is used, following additional principle applies:
  • The UE can use the PC5 QoS parameters for PC5 QoS handling.
When the network scheduled operation mode for NR PC5 is used, the following additional principles apply:
  • The UE provides PC5 QoS information (related to PC5 QoS parameters), Destination Layer-2 ID(s) and communication mode to the NG-RAN and NG-RAN may provide AS layer configurations and configure the mapping of PC5 QoS flow to radio bearer as defined in TS 38.331 and TS 36.331.
  • The UE provides PC5 QoS information (related to PC5 QoS parameters) and Destination information (related to Destination Layer-2 ID(s)) to the NG-RAN for resource request as defined in TS 38.331 and TS 36.331.
  • The NG-RAN authorizes the UE-provided PC5 QoS information based on PCF-provisioned PC5 QoS parameters as defined in clause 6.5.7.
  • The NG-RAN uses UE-PC5-AMBR for capping the UE PC5 transmission in the resources management.
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5.4.1.3  QoS handling for groupcast mode V2X communication over PC5 reference pointWord‑p. 30

The QoS handling described in clause 5.4.1.2 is applied.

5.4.1.4  QoS handling for unicast mode V2X communication over PC5 reference pointWord‑p. 30

The QoS handling described in clause 5.4.1.2 is applied with the following additions:
  • The PFI and PC5 QoS parameters are negotiated during the Layer-2 link establishment procedure, as described in clause 6.3.3.1, or during the Layer-2 link modification procedure, as described in clause 6.3.3.4.
When the network scheduled operation mode for NR PC5 is used, following additional principle applies:
  • NG-RAN uses the PC5 LINK-AMBR for capping the UE PC5 unicast link transmission in the resources management.
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5.4.2  PC5 QoS parametersWord‑p. 30

5.4.2.1  PQIWord‑p. 30

A PQI is a special 5QI, as defined in clause 5.7.2.1 of TS 23.501, and is used as a reference to PC5 QoS characteristics defined in clause 5.4.3, i.e. parameters that control QoS forwarding treatment for the packets over PC5 reference point.
Standardized PQI values have one-to-one mapping to a standardized combination of PC5 QoS characteristics as specified in Table 5.4.4-1.
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5.4.2.2  PC5 Flow Bit RatesWord‑p. 30

For GBR QoS Flows only, the following additional PC5 QoS parameters exist:
  • Guaranteed Flow Bit Rate (GFBR);
  • Maximum Flow Bit Rate (MFBR).
The GFBR and MFBR as defined in clause 5.7.2.5 of TS 23.501 are used for bit rate control on PC5 reference point over the Averaging Time Window. For PC5 communication, the same GFBR and MFBR are used for both directions.

5.4.2.3  PC5 Link Aggregated Bit RatesWord‑p. 31

A PC5 unicast link is associated with the following aggregate rate limit QoS parameter:
  • per link Aggregate Maximum Bit Rate (PC5 LINK-AMBR).
The PC5 LINK-AMBR limits the aggregate bit rate that can be expected to be provided across all Non-GBR QoS Flows with a peer UE over PC5 unicast link. The PC5 LINK-AMBR is measured over an AMBR averaging window which is a standardized value. The PC5 LINK-AMBR is not applicable to GBR QoS Flows. PC5 LINK-AMBR is applied to one PC5 unicast link, which means aggregate bit rate of one PC5 unicast link should not exceed PC5 LINK-AMBR.
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5.4.2.4  RangeWord‑p. 31

The Range value indicates the applicability of the PC5 QoS parameters in PC5 communication, i.e. when the receiving UEs are not within the Range specified distance from the transmitting UE, the communication is best effort. Lower layer (PHY/MAC layer) may use the Range to determine the corresponding packet handling, e.g. HARQ as defined in TS 38.300, to achieve the QoS guarantee indicated by PC5 QoS parameters.
Range is in the unit of meters. The UE is configured with the maximum Range value it can use for a particular V2X service. A V2X service may request a different range value, and the V2X layer ensures that it does not exceed the maximum Range value.
Range is only used for groupcast mode communication over PC5 reference point.
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5.4.2.5  Default ValuesWord‑p. 31

A UE may be configured with default values for PC5 QoS parameters for a particular V2X service type as specified in clause 5.1.2.1. The default value will be used if the corresponding PC5 QoS parameter is not provided by upper layer.

5.4.3  PC5 QoS characteristicsWord‑p. 31

5.4.3.1  GeneralWord‑p. 31

This clause specifies the PC5 QoS characteristics associated with PQI. The following characteristics defined in TS 23.501 applies, with differences explained in following clauses:
  1. Resource Type (GBR, Delay critical GBR or Non-GBR);
  2. Priority Level;
  3. Packet Delay Budget;
  4. Packet Error Rate;
  5. Averaging window (for GBR and Delay-critical GBR resource type only);
  6. Maximum Data Burst Volume (for Delay-critical GBR resource type only).
Standardized or pre-configured PC5 QoS characteristics, are indicated through the PQI value.
V2X layer may derive non-standardized PC5 QoS characteristics by overriding the standardized or pre-configured value of PC5 QoS characteristics based on V2X Application Requirements from V2X application layer and provide the whole set of non-standardized PC5 QoS characteristics to AS layer.
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5.4.3.2  Resource TypeWord‑p. 31

Resource Type is defined in clause 5.7.3.2 of TS 23.501.

5.4.3.3  Priority LevelWord‑p. 32

The Priority Level for NR PC5 has the same format and meaning as the Priority value of the ProSe Per-Packet Priority (PPPP) for LTE PC5 defined in TS 23.285. For LTE PC5, the PPPP value also reflects the latency requirement and the PDB derivation is according to TS 23.285, i.e. the low PDB is mapped to the high priority PPPP value. On the other hand, for NR PC5, the PDB is derived from the PQI Table as defined in clause 5.4.4.
The Priority Level shall be used to different treatment of V2X service data across different modes of communication, i.e. broadcast, groupcast, and unicast. In the case when all QoS requirements cannot be fulfilled for all the PC5 service data associated with that PC5 reference point, the Priority Level shall be used to select for which PC5 service data the QoS requirements are prioritized such that a PC5 service data packet with Priority Level value N is prioritized over a PC5 service data packet with higher Priority Level values, i.e. N+1, N+2, etc. (lower number meaning higher priority).
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5.4.3.4  Packet Delay BudgetWord‑p. 32

The Packet Delay Budget (PDB) associated with the PQI is equivalent to the PDB defined in clause 5.7.3.4 of TS 23.501. However, when used for PC5 communication, the PDB associated with the PQI defines an upper bound for the time that a packet may be delayed between sending UE and receiving UE(s) over PC5 reference point.

5.4.3.5  Packet Error RateWord‑p. 32

The Packet Error Rate (PER) is defined in clause 5.7.3.5 of TS 23.501.

5.4.3.6  Averaging WindowWord‑p. 32

The Averaging Window is defined in clause 5.7.3.6 of TS 23.501.

5.4.3.7  Maximum Data Burst VolumeWord‑p. 32

Maximum Data Burst Volume (MDBV) is defined in clause 5.7.3.7 of TS 23.501.
MDBV denotes the largest amount of data that the PC5 reference point is required to serve within a period of PDB of the PQI.
The MDBV may also be indicated by upper layer, it shall be used instead of the default value.

5.4.4  Standardized PQI to QoS characteristics mappingWord‑p. 32

The one-to-one mapping of standardized PQI values to PC5 QoS characteristics is specified in Table 5.4.4-1.
PQI Value Resource Type Default Priority Level Packet Delay Budget Packet Error Rate Default Maximum Data Burst Volume Default Averaging Window Example Services
21GBR
(NOTE 1)
320 ms10-4N/A2000 msPlatooning between UEs - Higher degree of automation;
Platooning between UE and RSU - Higher degree of automation
22450 ms10-2N/A2000 msSensor sharing - higher degree of automation
233100 ms10-4N/A2000 msInformation sharing for automated driving - between UEs or UE and RSU - higher degree of automation
55Non-GBR310 ms10-4N/AN/ACooperative lane change - higher degree of automation
56620 ms10-4N/AN/APlatooning informative exchange - low degree of automation;
Platooning - information sharing with RSU
57525 ms10-1N/AN/ACooperative lane change - lower degree of automation
584100 ms10-1N/AN/A Sensor information sharing - lower degree of automation
596500 ms10-2N/AN/APlatooning - reporting to an RSU
90Delay Critical GBR (NOTE 1)310 ms10-42000 bytes2000 msCooperative collision avoidance;
Sensor sharing - Higher degree of automation;
Video sharing - higher degree of automation
9123 ms10-52000 bytes2000 msEmergency trajectory alignment; Sensor sharing - Higher degree of automation
NOTE:
GBR and Delay Critical GBR PQIs can only be used for unicast PC5 communications.
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5.4.5  QoS handling for V2X communication over Uu reference pointWord‑p. 34

5.4.5.1  GeneralWord‑p. 34

The V2X service data can be delivered via Non-GBR QoS Flow as well as GBR QoS Flow (i.e. using the GBR resource type or the Delay-critical GBR resource type) as specified in TS 23.501.

5.4.5.2  Notification on QoS Sustainability Analytics to the V2X Application ServerWord‑p. 34

5.4.5.2.1  GeneralWord‑p. 34
A V2X Application Server may request notifications on QoS Sustainability Analytics for an indicated geographic area and time interval in order to adjust the application behaviour in advance with potential QoS change. The V2X Application Server may also request past statistical information for the purposes of adjustment of the application, how V2X Application Server makes use of such data is outside of 3GPP scope. Clause 6.4.1 describes the procedure for such notification from 5GS.
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5.4.5.2.2  Functional descriptionWord‑p. 34
The potential QoS change to assist application adjustment is based on the notification of QoS Sustainability Analytics defined in clause 6.9 of TS 23.288. The V2X Application Server acting as an Application Function communicates with the NEF which corresponds to the NF consumer in clause 6.9.4 of TS 23.288.
The V2X Application Server can either subscribe to notifications from the NEF (i.e., a Subscribe-Notify model) or request a single notification from the NEF (i.e. a Request-Response model). The V2X Application Server request contains the following parameters:
  • Analytics ID = "QoS Sustainability";
  • Target of Analytics Reporting: "any UE";
  • Analytics Filter Information:
    • Optional maximum number of objects;
    • QoS requirements:
      • 5QI (standardized or pre-configured), and applicable additional QoS parameters and the corresponding values (conditional, i.e., it is needed for GBR 5QIs to know the GFBR); or
      • the QoS Characteristics attributes including Resource Type, PDB and PER and their values;
    • Location information (the details are specified in clause 6.9.1 of TS 23.288);
    • S-NSSAI (optional, if available in the V2X Application Server).
    • Analytics target period (the details are specified in clause 6.9.1 of TS 23.288);
    • Reporting Threshold(s) (the details are specified in clause 6.9.1 of TS 23.288);
    • In a subscription, the Notification Correlation Id and the Notification Target Address.
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5.4.5.3  QoS Change based on Extended NG-RAN Notification to support Alternative Service RequirementsWord‑p. 34

To support V2X applications that can operate with different configurations (e.g. different bitrates or delay requirements), the V2X Application Server (V2X AS), acting as the Application Function, can provide, in addition to the requested level of service requirements, Alternative Service Requirements to the 5GS. This enables the 5GS to act on the Alternative Service Requirements and apply them for the extended NG-RAN notification, as described in TS 23.501 and TS 23.503.
The V2X AS can use the related procedures specified in clause 4.15.6.6 of TS 23.502 to influence the QoS provided to the V2X service. If so, the V2X AS includes Alternative Service Requirements as specified in clause 6.1.3.22 of TS 23.503 when providing service information to the PCF.
The QoS change based on extended NG-RAN notification operates within the 5GS QoS model as specified in TS 23.501 and TS 23.503.
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5.5  Subscription to V2X servicesWord‑p. 35

The user's profile in the UDM contains the subscription information to give the user permission to use V2X services.
At any time, the operator can remove the UE subscription rights for V2X services from user's profile in the UDM, and revoke the user's permission to use V2X services.
The following subscription information is defined for V2X services:
  1. whether the UE is authorized to perform V2X communication over PC5 reference point as Vehicle UE, Pedestrian UE, or both, including for LTE PC5 and for NR PC5.
  2. UE-PC5-AMBR per PC5 RAT, including UE-PC5-AMBR for LTE PC5 and UE-PC5-AMBR for NR PC5.
  3. the list of the PLMNs where the UE is authorized to perform V2X communication over PC5 reference point. For each PLMN in the list, the RAT(s) over which the UE is authorized to perform V2X communications over PC5 reference point.
  4. PC5 QoS parameters as defined in clause 5.4.2 used by NG-RAN.
The UDM may retrieve a) and b) from the UDR. a) and b) are provided by the UDM to the AMF during UE Registration procedure as defined in clause 4.2.2.2 of TS 23.502 using Nudm_SDM service for Subscription data type "V2X Subscription data" and the AMF provides a) and b) to NG-RAN as part of the UE context information.
c) and d) are provided by the UDR to the PCF during the UE Policy Association Establishment procedure as defined in clause 4.16.11 of TS 23.502 and UE Policy Association Modification procedure as defined in clause 4.16.12 of TS 23.502 using Nudr service for Data Set "Policy Data" and Data Subset "Policy Set Entry". If the subscription information provided to the PCF from UDR is changed (e.g., PC5 QoS related parameters, the list of PLMNs where the UE is authorized to perform V2X communication over PC5 reference point), the PCF initiates the UE Configuration Update procedure as specified in clause 6.2.2.
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5.6  IdentifiersWord‑p. 35

5.6.1  Identifiers for V2X communication over PC5 reference pointWord‑p. 35

5.6.1.1  GeneralWord‑p. 35

Each UE has one or more Layer-2 IDs for V2X communication over PC5 reference point, consisting of:
  • Source Layer-2 ID(s); and
  • Destination Layer-2 ID(s).
Source and destination Layer-2 IDs are included in layer-2 frames sent on the layer-2 link of the PC5 reference point identifying the layer-2 source and destination of these frames. Source Layer-2 IDs are always self-assigned by the UE originating the corresponding layer-2 frames.
The selection of the source and destination Layer-2 ID(s) by a UE depends on the communication mode of V2X communication over PC5 reference point for this layer-2 link, as described in clause 5.6.1.2, clause 5.6.1.3, and clause 5.6.1.4. The source Layer-2 IDs may differ between different communication modes.
When IP-based V2X communication is supported for broadcast and groupcast modes of V2X communication over PC5 reference point, the source IP address is allocated as described in clause 5.2.1.5.
If the UE has an active V2X application that requires privacy support in the current Geographical Area, as identified by configuration described in clause 5.1.2.1, in order to ensure that a source UE (e.g. vehicle) cannot be tracked or identified by any other UEs (e.g. vehicles) beyond a certain short time-period required by the application, the source Layer-2 ID shall be changed over time and shall be randomized. For IP-based V2X communication over PC5 reference point, the source IP address shall also be changed over time and shall be randomized. The change of the identifiers of a source UE must be synchronized across layers used for PC5, (e.g. when the Application Layer ID changes, the source Layer-2 ID and the source IP address need to be changed).
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5.6.1.2  Identifiers for broadcast mode V2X communication over PC5 reference pointWord‑p. 36

For broadcast mode of V2X communication over PC5 reference point, the UE is configured with the destination Layer-2 ID(s) to be used for V2X services. The destination Layer-2 ID for a V2X communication is selected based on the configuration as described in clause 5.1.2.1.
The UE self-selects a source Layer-2 ID. The UE may use different source Layer-2 IDs for different types of PC5 reference points, i.e. LTE based PC5 and NR based PC5.
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5.6.1.3  Identifiers for groupcast mode V2X communication over PC5 reference pointWord‑p. 36

For groupcast mode of V2X communication over PC5 reference point, the V2X application layer may provide group identifier information. When the group identifier information is provided by the V2X application layer, the UE converts the provided group identifier into a destination Layer-2 ID. When the group identifier information is not provided by the V2X application layer, the UE determines the destination Layer-2 ID based on configuration of the mapping between V2X service type and Layer-2 ID, as specified in clause 5.1.2.1.
The UE self-selects a source Layer-2 ID.
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5.6.1.4  Identifiers for unicast mode V2X communication over PC5 reference pointWord‑p. 36

For unicast mode of V2X communication over PC5 reference point, the destination Layer-2 ID used depends on the communication peer. The Layer-2 ID of the communication peer, identified by the Application Layer ID, may be discovered during the establishment of the PC5 unicast link, or known to the UE via prior V2X communications, e.g. existing or prior unicast link to the same Application Layer ID, or obtained from application layer service announcements. The initial signalling for the establishment of the PC5 unicast link may use the known Layer-2 ID of the communication peer, or a default destination Layer-2 ID associated with the V2X service type configured for PC5 unicast link establishment, as specified in clause 5.1.2.1. During the PC5 unicast link establishment procedure, Layer-2 IDs are exchanged, and should be used for future communication between the two UEs, as specified in clause 6.3.3.1.
The Application Layer ID is associated with one or more V2X applications within the UE. If UE has more than one Application Layer IDs, each Application Layer ID of the same UE may be seen as different UE's Application Layer ID from the peer UE's perspective.
The UE maintains a mapping between the Application Layer IDs and the source Layer-2 IDs used for the PC5 unicast links, as the V2X application layer does not use the Layer-2 IDs. This allows the change of source Layer-2 ID without interrupting the V2X applications.
When Application Layer IDs change, the source Layer-2 ID(s) of the PC5 unicast link(s) shall be changed if the link(s) was used for V2X communication with the changed Application Layer IDs.
Based on privacy configuration as specified in clause 5.1.2.1, the update of the new identifiers of a source UE to the peer UE for the established unicast link may cause the peer UE to change its Layer-2 ID and optionally IP address/prefix if IP communication is used as defined in clause 6.3.3.2.
A UE may establish multiple PC5 unicast links with a peer UE and use the same or different source Layer-2 IDs for these PC5 unicast links.
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5.7  Support for V2X communication for UEs in limited service stateWord‑p. 37

For UE in limited service state, as defined in TS 23.122, V2X communication is only allowed over PC5 reference point.
UEs that are authorized to use V2X communication over PC5 reference point shall be able to use V2X communication over PC5 reference point when in limited service state following the principles defined in clause 5.1.2.2 for V2X communication over PC5 reference point when the UE enters in limited service state in 5GS:
  • because UE cannot find a suitable cell of the selected PLMN as described in TS 23.122; or
  • as the result of receiving one of the following reject reasons defined in TS 23.122:
    • a "PLMN not allowed" response to a registration request or;
    • a "5GS services not allowed" response to a registration request or service request.
A UE in limited service state shall only use the radio resources and procedure available in CM-IDLE mode for V2X communication over PC5 reference point, for details see TS 36.300 and TS 38.300.
UEs shall not use V2X communication over PC5 reference point using the "operator-managed" radio resources, as specified in clause 5.1.2.1, if the UE has entered in limited service state due to all other situations (e.g. no SIM in the MS, an "illegal MS" or "illegal ME" response to a registration request, or an "IMSI unknown in HLR" response to a registration request) defined in TS 23.122, where the UE is unable to obtain normal service from a PLMN. The UEs may use V2X communication over PC5 reference point using the "non-operator-managed" radio resources, as specified in clause 5.1.2.1, according to the principles defined in clause 5.1.2.2.
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5.8  Interworking between EPS V2X and 5GS V2XWord‑p. 37

5.8.1  V2X Policy and parameter provisioningWord‑p. 37

When the UE is in 5GS or EPS, the UE shall use the valid V2X policy and parameters provisioned by the PCF in 5GC or by the V2X Control Function in EPC for V2X communication. The V2X related parameters for EPS defined in TS 23.285 can be either provided by the PCF or by the V2X Control Function, while the V2X policy and parameters involving 5GS are provided by the PCF only. If the UE does not have valid V2X policy and parameters, the UE shall request the network to provision the V2X policy and parameters.
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5.8.2  PC5 OperationWord‑p. 37

PC5 communication can be supported with proper UE configurations by taking into account e.g. regional regulations, deployments, and UE support for LTE PC5 and/or NR PC5 RATs.
V2X communication over NR PC5 reference point in network scheduled operation mode is supported in EPS (i.e. EN-DC architecture defined in TS 37.340) as defined in TS 23.285 and TS 36.331.
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5.8.3  Mobility between EPS and 5GS over UuWord‑p. 37

Interworking specified in clause 5.17 of TS 23.501 and clause 4.11 of TS 23.502 is applied to mobility between EPS and 5GS over Uu reference point with the following additions:
  • For N26 based handover, V2X related data including the "V2X services authorized" indication per PC5 RAT, UE-PC5-AMBR per PC5 RAT, and PC5 QoS parameters are transferred between AMF and MME, and are included in Handover Request message sent to the target RAN node.
Any Unstructured type PDU Session established in 5GC based on the UE configuration as described in clause 5.1.3.1 is allowed to be transferred to EPC as non-IP PDN connection when non-IP PDN type is supported by UE and EPC as specified in clause 5.17.2.1 of TS 23.501.
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5.9  Support of QoS aware NR PC5 power efficiency for pedestrian UEs |R17|Word‑p. 38

For NR based unicast, groupcast and broadcast mode communication over PC5 reference point, PC5 DRX operations are supported to enable pedestrian UE power saving.
The V2X layer determines the respective V2X service types, and derives the corresponding PC5 QoS parameters based on either the mapping of V2X service types to PC5 QoS parameters, or the V2X Application Requirements for the V2X service type provided by the application layer. The V2X layer passes the PC5 QoS parameters and destination Layer-2 ID to the AS layer as specified in clauses 6.3.1, 6.3.2 and 6.3.3.
For broadcast and groupcast, the V2X layer determines the NR Tx Profile for the respective V2X service type based on the configuration described in clause 5.1.2.1 and provides the NR Tx Profile to the AS layer as specified in clauses 6.3.1 and 6.3.2.
Support for PC5 DRX operations in the AS layer is specified in TS 38.300.
When the PC5 DRX operation is needed, e.g. based on the NR Tx Profile in case of broadcast or groupcast, the AS layer determines the PC5 DRX parameter values for V2X communication over PC5 reference point, taking into account, e.g., PC5 QoS parameters and/or destination Layer-2 ID provided by the V2X layer.
For unicast, two UEs may negotiate the PC5 DRX configuration in the AS layer, and the PC5 DRX parameter values can be configured per a pair of source and destination Layer-2 IDs and per direction in the AS layer.
For broadcast and groupcast when the UE is "not served by E-UTRA" and "not served by NR", the UE uses the provisioned PC5 DRX configuration for PC5 DRX operation as specified in clause 5.1.2.1.
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