5.10 Sidelink

36.3313GPPEvolved Universal Terrestrial Radio Access (E-UTRA)Protocol specificationRadio Resource Control (RRC)Release 15TS

5.10.1 Introduction

The sidelink communication and associated synchronisation resource configuration applies for the frequency at which it was received/ acquired. Moreover, for a UE configured with one or more SCells, the sidelink communication and associated synchronisation resource configuration provided by dedicated signalling applies for the PCell/ the primary frequency. The sidelink discovery and associated synchronisation resource configuration applies for the frequency at which it was received/ acquired or the indicated frequency in the configuration. For a UE configured with one or more SCells, the sidelink discovery and associated synchronisation resource configuration provided by dedicated signalling applies for the PCell/ the primary frequency / any other indicated frequency.

NOTE 1: Upper layers configure the UE to receive or transmit sidelink communication on a specific frequency, to monitor or transmit non-PS related sidelink discovery announcements on one or more frequencies or to monitor or transmit PS related sidelink discovery announcements on a specific frequency, but only if the UE is authorised to perform these particular ProSe related sidelink activities.

NOTE 2: It is up to UE implementation which actions to take (e.g. termination of unicast services, detach) when it is unable to perform the desired sidelink activities, e.g. due to UE capability limitations.

Sidelink communication consists of one-to-many and one-to-one sidelink communication. One-to-many sidelink communication consists of relay related and non-relay related one-to-many sidelink communication. One-to-one sidelink communication consists of relay related and non-relay related one-to-one sidelink communication. In relay related one-to-one sidelink communication the communicating parties consist of one sidelink relay UE and one sidelink remote UE.

Sidelink discovery consists of public safety related (PS related) and non-PS related sidelink discovery. PS related sidelink discovery consists of relay related and non-relay related PS related sidelink discovery. Upper layers indicate to RRC whether a particular sidelink announcement is PS related or non-PS related.

Upper layers indicate to RRC whether a particular sidelink procedure is V2X related or not.

The specification covers the use of UE to network sidelink relays by specifying the additional requirements that apply for a sidelink relay UE and a sidelink remote UE. I.e. for such UEs the regular sidelink UE requirements equally apply unless explicitly stated otherwise.

5.10.1a Conditions for sidelink communication operation

When it is specified that the UE shall perform sidelink communication operation only if the conditions defined in this clause are met, the UE shall perform sidelink communication operation only if:

1> if the UE’s serving cell is suitable (RRC_IDLE or RRC_CONNECTED); and if either the selected cell on the frequency used for sidelink communication operation belongs to the registered or equivalent PLMN as specified in TS 24.334 [69] or the UE is out of coverage on the frequency used for sidelink communication operation as defined in TS 36.304 [4], clause 11.4; or

1> if the UE is camped on a serving cell (RRC_IDLE) on which it fulfils the conditions to support sidelink communication in limited service state as specified in TS 23.303 [68], clause 4.5.6; and if either the serving cell is on the frequency used for sidelink communication operation or the UE is out of coverage on the frequency used for sidelink communication operation as defined in TS 36.304 [4], clause 11.4; or

1> if the UE has no serving cell (RRC_IDLE);

5.10.1b Conditions for PS related sidelink discovery operation

When it is specified that the UE shall perform PS related sidelink discovery operation only if the conditions defined in this clause are met, the UE shall perform PS related sidelink discovery operation only if:

1> if the UE’s serving cell is suitable (RRC_IDLE or RRC_CONNECTED); and if either the selected cell on the frequency used for PS related sidelink discovery operation belongs to the registered or other PLMN as specified in TS 24.334 [69] or the UE is out of coverage on the frequency used for PS related sidelink discovery operation as defined in TS 36.304 [4], clause 11.4; or

1> if the UE is camped on a serving cell (RRC_IDLE) on which it fulfils the conditions to support sidelink discovery in limited service state as specified in TS 23.303 [68], clause 4.5.6; and if either the serving cell is on the frequency used for PS related sidelink discovery operation or the UE is out of coverage on the frequency used for PS related sidelink discovery operation as defined in TS 36.304 [4], clause 11.4; or

1> if the UE has no serving cell (RRC_IDLE);

5.10.1c Conditions for non-PS related sidelink discovery operation

When it is specified that the UE shall perform non-PS related sidelink discovery operation only if the conditions defined in this clause are met, the UE shall perform non-PS related sidelink discovery operation only if:

1> if the UE’s serving cell (RRC_IDLE) or PCell (RRC_CONNECTED) is suitable; and if the selected cell on the frequency used for non-PS related sidelink discovery operation belongs to the registered or other PLMN as specified in TS 24.334 [69].

5.10.1d Conditions for V2X sidelink communication operation

When it is specified that the UE shall perform V2X sidelink communication operation only if the conditions defined in this clause are met, the UE shall perform V2X sidelink communication operation only if:

1> if the UE’s serving cell is suitable (RRC_IDLE or RRC_CONNECTED); and if either the selected cell on the frequency used for V2X sidelink communication operation belongs to the registered or equivalent PLMN as specified in TS 24.334 [69] or the UE is out of coverage on the frequency used for V2X sidelink communication operation as defined in TS 36.304 [4], clause 11.4; or

1> if the UE’s serving cell (for RRC_IDLE or RRC_CONNECTED) fulfils the conditions to support V2X sidelink communication in limited service state as specified in TS 23.285 [78], clause 4.4.8; and if either the serving cell is on the frequency used for V2X sidelink communication operation or the UE is out of coverage on the frequency used for V2X sidelink communication operation as defined in TS 36.304 [4], clause 11.4; or

1> if the UE has no serving cell (RRC_IDLE);

5.10.2 Sidelink UE information

5.10.2.1 General

Figure 5.10.2-1: Sidelink UE information

The purpose of this procedure is to inform E-UTRAN that the UE is interested or no longer interested to receive sidelink communication or discovery, to receive V2X sidelink communication, as well as to request assignment or release of transmission resources for sidelink communication or discovery announcements or V2X sidelink communication or sidelink discovery gaps, to report parameters related to sidelink discovery from system information of inter-frequency/PLMN cells and to report the synchronization reference used by the UE for V2X sidelink communication.

5.10.2.2 Initiation

A UE capable of sidelink communication or V2X sidelink communication or sidelink discovery that is in RRC_CONNECTED may initiate the procedure to indicate it is (interested in) receiving sidelink communication or V2X sidelink communication or sidelink discovery in several cases including upon successful connection establishment, upon change of interest, upon change to a PCell broadcasting SystemInformationBlockType18 or SystemInformationBlockType19 or SystemInformationBlockType21 including sl-V2X-ConfigCommon. A UE capable of sidelink communication or V2X sidelink communication or sidelink discovery may initiate the procedure to request assignment of dedicated resources for the concerned sidelink communication transmission or discovery announcements or V2X sidelink communication transmission or to request sidelink discovery gaps for sidelink discovery transmission or sidelink discovery reception and a UE capable of inter-frequency/PLMN sidelink discovery parameter reporting may initiate the procedure to report parameters related to sidelink discovery from system information of inter-frequency/PLMN cells.

NOTE 1: A UE in RRC_IDLE that is configured to transmit sidelink communication / V2X sidelink communication / sidelink discovery announcements, while SystemInformationBlockType18/ SystemInformationBlockType19/ SystemInformationBlockType21 including sl-V2X-ConfigCommon or SystemInformationBlockType26 does not include the resources for transmission (in normal conditions), initiates connection establishment in accordance with 5.3.3.1a.

Upon initiating the procedure, the UE shall:

1> if SystemInformationBlockType18 is broadcast by the PCell:

2> ensure having a valid version of SystemInformationBlockType18 for the PCell;

2> if configured by upper layers to receive sidelink communication:

3> if the UE did not transmit a SidelinkUEInformation message since last entering RRC_CONNECTED state; or

3> if since the last time the UE transmitted a SidelinkUEInformation message the UE connected to a PCell not broadcasting SystemInformationBlockType18; or

NOTE 2: After handover/ re-establishment from a source PCell not broadcasting SystemInformationBlockType18 the UE repeats the same interest information that it provided previously as such a source PCell may not forward the interest information.

3> if the last transmission of the SidelinkUEInformation message did not include commRxInterestedFreq; or if the frequency configured by upper layers to receive sidelink communication on has changed since the last transmission of the SidelinkUEInformation message:

4> initiate transmission of the SidelinkUEInformation message to indicate the sidelink communication reception frequency of interest in accordance with 5.10.2.3;

2> else:

3> if the last transmission of the SidelinkUEInformation message included commRxInterestedFreq:

4> initiate transmission of the SidelinkUEInformation message to indicate it is no longer interested in sidelink communication reception in accordance with 5.10.2.3;

2> if configured by upper layers to transmit non-relay related one-to-many sidelink communication:

3> if the UE did not transmit a SidelinkUEInformation message since last entering RRC_CONNECTED state; or

3> if since the last time the UE transmitted a SidelinkUEInformation message the UE connected to a PCell not broadcasting SystemInformationBlockType18; or

3> if the last transmission of the SidelinkUEInformation message did not include commTxResourceReq; or if the information carried by the commTxResourceReq has changed since the last transmission of the SidelinkUEInformation message:

4> initiate transmission of the SidelinkUEInformation message to indicate the non-relay related one-to-many sidelink communication transmission resources required by the UE in accordance with 5.10.2.3;

2> else:

3> if the last transmission of the SidelinkUEInformation message included commTxResourceReq:

4> initiate transmission of the SidelinkUEInformation message to indicate it no longer requires non-relay related one-to-many sidelink communication transmission resources in accordance with 5.10.2.3;

2> if configured by upper layer to transmit relay related one-to-many sidelink communication:

3> if the UE did not transmit a SidelinkUEInformation message since entering RRC_CONNECTED state; or

3> if since the last time the UE transmitted a SidelinkUEInformation message the UE connected to a PCell not broadcasting SystemInformationBlockType18, connected to a PCell not broadcasting SystemInformationBlockType19 or broadcasting SystemInformationBlockType19 not including discConfigRelay; or

3> if the last transmission of SidelinkUEInformation message did not include commTxResourceReqRelay; or if the information carried by the commTxResourceReqRelay has changed since the last transmission of the SidelinkUEInformation message:

4> if the UE is acting as sidelink relay UE:

5> initiate transmission of the SidelinkUEInformation message to indicate the relay related one-to-many sidelink communication transmission resources required by the UE in accordance with 5.10.2.3;

2> else:

3> if the last transmission of the SidelinkUEInformation message included commTxResourceReqRelay:

4> initiate transmission of the SidelinkUEInformation message to indicate it no longer requires relay related one-to-many sidelink communication transmission resources in accordance with 5.10.2.3;

2> if configured by upper layers to transmit non-relay related one-to-one sidelink communication:

3> if the UE did not transmit a SidelinkUEInformation message since last entering RRC_CONNECTED state; or

3> if since the last time the UE transmitted a SidelinkUEInformation message the UE connected to a PCell not broadcasting SystemInformationBlockType18 or connected to a PCell broadcasting SystemInformationBlockType18 not including commTxResourceUC-ReqAllowed; or

3> if the last transmission of the SidelinkUEInformation message did not include commTxResourceReqUC; or if the information carried by the commTxResourceReqUC has changed since the last transmission of the SidelinkUEInformation message:

4> if commTxResourceUC-ReqAllowed is included in SystemInformationBlockType18:

5> initiate transmission of the SidelinkUEInformation message to indicate the non-relay related one-to-one sidelink communication transmission resources required by the UE in accordance with 5.10.2.3;

2> else:

3> if the last transmission of the SidelinkUEInformation message included commTxResourceReqUC:

4> initiate transmission of the SidelinkUEInformation message to indicate it no longer requires non-relay related one-to-one sidelink communication transmission resources in accordance with 5.10.2.3;

2> if configured by upper layers to transmit relay related one-to-one sidelink communication:

3> if the UE did not transmit a SidelinkUEInformation message since last entering RRC_CONNECTED state; or

3> if since the last time the UE transmitted a SidelinkUEInformation message the UE connected to a PCell not broadcasting SystemInformationBlockType18, connected to a PCell not broadcasting SystemInformationBlockType19 or broadcasting SystemInformationBlockType19 not including discConfigRelay; or

3> if the last transmission of the SidelinkUEInformation message did not include commTxResourceReqRelayUC; or if the information carried by the commTxResourceReqRelayUC has changed since the last transmission of the SidelinkUEInformation message:

4> if the UE is acting as sidelink relay UE; or

4> if the UE has a selected sidelink relay UE; and if SystemInformationBlockType19 is broadcast by the PCell and includes discConfigRelay; and if the sidelink remote UE threshold conditions as specified in 5.10.11.5 are met;

5> initiate transmission of the SidelinkUEInformation message to indicate the relay related one-to-one sidelink communication transmission resources required by the UE in accordance with 5.10.2.3;

2> else:

3> if the last transmission of the SidelinkUEInformation message included commTxResourceReqRelayUC:

4> initiate transmission of the SidelinkUEInformation message to indicate it no longer requires relay related one-to-one sidelink communication transmission resources in accordance with 5.10.2.3;

1> if SystemInformationBlockType19 is broadcast by the PCell:

2> ensure having a valid version of SystemInformationBlockType19 for the PCell;

2> if configured by upper layers to receive sidelink discovery announcements on a serving frequency or on one or more frequencies included in discInterFreqList, if included in SystemInformationBlockType19 of the PCell:

3> if the UE did not transmit a SidelinkUEInformation message since last entering RRC_CONNECTED state; or

3> if since the last time the UE transmitted a SidelinkUEInformation message the UE connected to a PCell not broadcasting SystemInformationBlockType19; or

3> if the last transmission of the SidelinkUEInformation message did not include discRxInterest:

4> initiate transmission of the SidelinkUEInformation message to indicate it is interested in sidelink discovery reception in accordance with 5.10.2.3;

2> else:

3> if the last transmission of the SidelinkUEInformation message included discRxInterest:

4> initiate transmission of the SidelinkUEInformation message to indicate it is no longer interested in sidelink discovery reception in accordance with 5.10.2.3;

2> if the UE is configured by upper layers to transmit non-PS related sidelink discovery announcements on the primary frequency or on one or more frequencies included in discInterFreqList, if included in SystemInformationBlockType19 of the PCell, with discTxResourcesInterFreq included within discResourcesNonPS and not set to noTxOnCarrier:

3> if the UE did not transmit a SidelinkUEInformation message since last entering RRC_CONNECTED state; or

3> if since the last time the UE transmitted a SidelinkUEInformation message the UE connected to a PCell not broadcasting SystemInformationBlockType19 or connected to a PCell broadcasting SystemInformationBlockType19 not including discTxResourcesInterFreq within discResourcesNonPS or discTxResourcesInterFreq did not include all frequencies for which the UE will request resources; or

3> if the last transmission of the SidelinkUEInformation message did not include discTxResourceReq; or if the non-PS related sidelink discovery announcement resources required by the UE have changed (i.e. resulting in a change of discTxResourceReq) since the last transmission of the SidelinkUEInformation message:

4> initiate transmission of the SidelinkUEInformation message to indicate the non-PS related sidelink discovery announcement resources required by the UE in accordance with 5.10.2.3;

2> else:

3> if the last transmission of the SidelinkUEInformation message included discTxResourceReq:

4> initiate transmission of the SidelinkUEInformation message to indicate it no longer requires non-PS related sidelink discovery announcement resources in accordance with 5.10.2.3;

2> if configured by upper layers to transmit PS related sidelink discovery announcements on the primary frequency or, in case of non-relay PS related sidelink discovery announcements, on a frequency included in discInterFreqList, if included in SystemInformationBlockType19, with discTxResourcesInterFreq included within discResourcesPS and not set to noTxOnCarrier:

3> if the UE did not transmit a SidelinkUEInformation message since last entering RRC_CONNECTED state; or

3> if since the last time the UE transmitted a SidelinkUEInformation message the UE connected to a PCell not broadcasting SystemInformationBlockType19, connected to a PCell broadcasting SystemInformationBlockType19 not including discConfigPS, or in case of non-relay PS related transmission: (connected to a PCell broadcasting SystemInformationBlockType19 not including discTxResourcesInterFreq within discResourcesPS or for which discTxResourcesInterFreq did not include all frequencies for which the UE will request resources), or in case of relay related PS sidelink discovery announcements: (connected to a PCell broadcasting SystemInformationBlockType19 not including discConfigRelay) sidelink; or

3> if the last transmission of the SidelinkUEInformation message did not include discTxResourceReqPS; or if the PS related sidelink discovery announcement resources required by the UE have changed (i.e. resulting in a change of discTxResourceReqPS) since the last transmission of the SidelinkUEInformation message:

4> if configured by upper layers to transmit non-relay PS related sidelink discovery announcements; or

4> if the UE is acting as sidelink relay UE; and if SystemInformationBlockType19 includes discConfigRelay; and if the sidelink relay UE threshold conditions as specified in 5.10.10.4 are met; or

4> if the UE is selecting a sidelink relay UE / has a selected sidelink relay UE; and if SystemInformationBlockType19 includes discConfigRelay; and if the sidelink remote UE threshold conditions as specified in 5.10.11.5 are met:

5> initiate transmission of the SidelinkUEInformation message to indicate the PS related sidelink discovery announcement resources required by the UE in accordance with 5.10.2.3;

2> else:

3> if the last transmission of the SidelinkUEInformation message included discTxResourceReqPS:

4> initiate transmission of the SidelinkUEInformation message to indicate it no longer requires PS related sidelink discovery announcement resources in accordance with 5.10.2.3;

2> if configured by upper layers to monitor or transmit sidelink discovery announcements; and if the UE requires sidelink discovery gaps, to perform such actions:

3> if the UE did not transmit a SidelinkUEInformation message since last entering RRC_CONNECTED state; or

3> if since the last time the UE transmitted a SidelinkUEInformation message the UE connected to a PCell not broadcasting SystemInformationBlockType19 or connected to a PCell broadcasting SystemInformationBlockType19 not including gapRequestsAllowedCommon while at the same time the UE was not configured with gapRequestsAllowedDedicated; or

3> if the last transmission of the SidelinkUEInformation message did not include the gaps required to monitor or transmit the sidelink discovery announcements (i.e. UE requiring gaps to monitor discovery announcements while discRxGapReq was not included or UE requiring gaps to transmit discovery announcements while discTxGapReq was not included); or if the sidelink discovery gaps required by the UE have changed (i.e. resulting in a change of discRxGapReq or discTxGapReq) since the last transmission of the SidelinkUEInformation message:

4> if the UE is configured with gapRequestsAllowedDedicated set to true; or

4> if the UE is not configured with gapRequestsAllowedDedicated and gapRequestsAllowedCommon is included in SystemInformationBlockType19:

5> initiate transmission of the SidelinkUEInformation message to indicate the sidelink discovery gaps required by the UE in accordance with 5.10.2.3;

2> else:

3> if the last transmission of the SidelinkUEInformation message included discTxGapReq or discRxGapReq:

4> initiate transmission of the SidelinkUEInformation message to indicate it no longer requires sidelink discovery gaps in accordance with 5.10.2.3;

2> if the UE acquired the relevant parameters from the system information of one or more cells on a carrier included in the discSysInfoToReportConfig and T370 is running:

3> if the UE has configured lower layers to transmit or monitor the sidelink discovery announcements on those cells:

4> initiate transmission of the SidelinkUEInformation message to report the acquired system information parameters and stop T370;

1> if SystemInformationBlockType21 including sl-V2X-ConfigCommon is broadcast by the PCell:

2> ensure having a valid version of SystemInformationBlockType21 and SystemInformationBlockType26, if broadcast, for the PCell;

2> if configured by upper layers to receive V2X sidelink communication on a primary frequency or on one or more frequencies included in v2x-InterFreqInfoList, if included in SystemInformationBlockType21 or SystemInformationBlockType26 of the PCell:

3> if the UE did not transmit a SidelinkUEInformation message since last entering RRC_CONNECTED state; or

3> if since the last time the UE transmitted a SidelinkUEInformation message the UE connected to a PCell not broadcasting SystemInformationBlockType21 including sl-V2X-ConfigCommon; or

3> if the last transmission of the SidelinkUEInformation message did not include v2x-CommRxInterestedFreqList; or if the frequency(ies) configured by upper layers to receive V2X sidelink communication on has changed since the last transmission of the SidelinkUEInformation message:

4> initiate transmission of the SidelinkUEInformation message to indicate the V2X sidelink communication reception frequency(ies) of interest in accordance with 5.10.2.3;

2> else:

3> if the last transmission of the SidelinkUEInformation message included v2x-CommRxInterestedFreqList:

4> initiate transmission of the SidelinkUEInformation message to indicate it is no longer interested in V2X sidelink communication reception in accordance with 5.10.2.3;

2> if configured by upper layers to transmit V2X sidelink communication on a primary frequency or on one or more frequencies included in v2x-InterFreqInfoList, if included in SystemInformationBlockType21 or SystemInformationBlockType26 of the PCell:

3> if the UE did not transmit a SidelinkUEInformation message since last entering RRC_CONNECTED state; or

3> if since the last time the UE transmitted a SidelinkUEInformation message the UE connected to a PCell not broadcasting SystemInformationBlockType21 including sl-V2X-ConfigCommon; or

3> if the last transmission of the SidelinkUEInformation message did not include v2x-CommTxResourceReq; or if the information carried by the v2x-CommTxResourceReq has changed since the last transmission of the SidelinkUEInformation message:

4> initiate transmission of the SidelinkUEInformation message to indicate the V2X sidelink communication transmission resources required by the UE in accordance with 5.10.2.3;

2> else:

3> if the last transmission of the SidelinkUEInformation message included v2x-CommTxResourceReq:

4> initiate transmission of the SidelinkUEInformation message to indicate it no longer requires V2X sidelink communication transmission resources in accordance with 5.10.2.3;

5.10.2.3 Actions related to transmission of SidelinkUEInformation message

The UE shall set the contents of the SidelinkUEInformation message as follows:

1> if the UE initiates the procedure to indicate it is (no more) interested to receive sidelink communication or discovery or receive V2X sidelink communication or to request (configuration/ release) of sidelink communication or V2X sidelink communication or sidelink discovery transmission resources (i.e. UE includes all concerned information, irrespective of what triggered the procedure):

2> if SystemInformationBlockType18 is broadcast by the PCell:

3> if configured by upper layers to receive sidelink communication:

4> include commRxInterestedFreq and set it to the sidelink communication frequency;

3> if configured by upper layers to transmit non-relay related one-to-many sidelink communication:

4> include commTxResourceReq and set its fields as follows:

5> set carrierFreq to indicate the sidelink communication frequency i.e. the same value as indicated in commRxInterestedFreq if included;

5> set destinationInfoList to include the non-relay related one-to-many sidelink communication transmission destination(s) for which it requests E-UTRAN to assign dedicated resources;

3> if configured by upper layers to transmit non-relay related one-to-one sidelink communication; and

3> if commTxResourceUC-ReqAllowed is included in SystemInformationBlockType18:

4> include commTxResourceReqUC and set its fields as follows:

5> set carrierFreq to indicate the one-to-one sidelink communication frequency i.e. the same value as indicated in commRxInterestedFreq if included;

5> set destinationInfoList to include the non-relay related one-to-one sidelink communication transmission destination(s) for which it requests E-UTRAN to assign dedicated resources;

3> if configured by upper layers to transmit relay related one-to-one sidelink communication; and

3> if SystemInformationBlockType19 is broadcast by the PCell including discConfigRelay; and

3> if the UE is acting as sidelink relay UE; or if the UE has a selected sidelink relay UE; and if the sidelink remote UE threshold conditions as specified in 5.10.11.5 are met:

4> include commTxResourceReqRelayUC and set its fields as follows:

5> set destinationInfoList to include the one-to-one sidelink communication transmission destination(s) for which it requests E-UTRAN to assign dedicated resources;

4> include ue-Type and set it to relayUE if the UE is acting as sidelink relay UE and to remoteUE otherwise;

3> if configured by upper layers to transmit relay related one-to-many sidelink communication; and

3> if SystemInformationBlockType19 is broadcast by the PCell including discConfigRelay; and

3> if the UE is acting as sidelink relay UE:

4> include commTxResourceReqRelay and set its fields as follows:

5> set destinationInfoList to include the one-to-many sidelink communication transmission destination(s) for which it requests E-UTRAN to assign dedicated resources;

4> include ue-Type and set it to relayUE;

2> if SystemInformationBlockType19 is broadcast by the PCell:

3> if configured by upper layers to receive sidelink discovery announcements on a serving frequency or one or more frequencies included in discInterFreqList, if included in SystemInformationBlockType19:

4> include discRxInterest;

3> if the UE is configured by upper layers to transmit non-PS related sidelink discovery announcements:

4> for each frequency on which the UE is configured to transmit non-PS related sidelink discovery announcements that concerns the primary frequency or that is included in discInterFreqList with discTxResourcesInterFreq included within discResourcesNonPS and not set to noTxOnCarrier:

5> for the first frequency, include discTxResourceReq and set it to indicate the number of discovery messages for sidelink discovery announcement(s) for which it requests E-UTRAN to assign dedicated resources as well as the concerned frequency, if different from the primary;

5> for any additional frequency, include discTxResourceReqAddFreq and set it to indicate the number of discovery messages for sidelink discovery announcement(s) for which it requests E-UTRAN to assign dedicated resources as well as the concerned frequency;

3> if configured by upper layers to transmit PS related sidelink discovery announcements; and

3> if the frequency on which the UE is configured to transmit PS related sidelink discovery announcements either concerns the primary frequency or, in case of non-relay PS related sidelink discovery announcements, is included in discInterFreqList with discTxResources InterFreq included within discResourcesPS and not set to noTxOnCarrier:

4> if configured by upper layers to transmit non-relay PS related sidelink discovery announcements and SystemInformationBlockType19 includes discConfigPS; or

4> if the UE is acting as sidelink relay UE; and if SystemInformationBlockType19 includes discConfigRelay; and if the sidelink relay UE threshold conditions as specified in 5.10.10.4 are met; or

4> if the UE is selecting a sidelink relay UE / has a selected sidelink relay UE; and if SystemInformationBlockType19 includes discConfigRelay; and if the sidelink remote UE threshold conditions as specified in 5.10.11.5 are met:

5> include discTxResourceReqPS and set it to indicate the number of discovery messages for PS related sidelink discovery announcement(s) for which it requests E-UTRAN to assign dedicated resources as well as the concerned frequency, if different from the primary;

2> if SystemInformationBlockType21 is broadcast by the PCell and SystemInformationBlockType21 includes sl-V2X-ConfigCommon:

3> if configured by upper layers to receive V2X sidelink communication:

4> include v2x-CommRxInterestedFreqList and set it to the frequency(ies) for V2X sidelink communication reception;

3> if configured by upper layers to transmit V2X sidelink communication:

4> if configured by upper layers to transmit P2X related V2X sidelink communication:

5> include p2x-CommTxType set to true;

4> include v2x-CommTxResourceReq and set its fields as follows for each frequency on which the UE is configured for V2X sidelink communication transmission:

5> set carrierFreqCommTx to indicate the frequency for V2X sidelink communication transmission;

5> set v2x-TypeTxSync to the current synchronization reference type used on the associated carrierFreqCommTx for V2X sidelink communication transmission;

5> set v2x-DestinationInfoList to include the V2X sidelink communication transmission destination(s) for which it requests E-UTRAN to assign dedicated resources;

1> else if the UE initiates the procedure to request sidelink discovery transmission and/ or reception gaps:

2> if the UE is configured with gapRequestsAllowedDedicated set to true; or

2> if the UE is not configured with gapRequestsAllowedDedicated and gapRequestsAllowedCommon is included in SystemInformationBlockType19:

3> if the UE requires sidelink discovery gaps to monitor the sidelink discovery announcements the UE is configured to monitor by upper layers:

4> include discRxGapReq and set it to indicate, for each frequency that either concerns the primary frequency or is included in discInterFreqList on which the UE is configured to monitor sidelink discovery announcements and for which it requires sidelink discovery gaps to do so, the gap pattern(s) as well as the concerned frequency, if different from the primary;

3> if the UE requires sidelink discovery gaps to transmit the sidelink discovery announcements the UE is configured to transmit by upper layers:

4> include discTxGapReq and set it to indicate, for each frequency that either concerns the primary or is included in discInterFreqList on which the UE is configured to transmit sidelink discovery announcements and for which it requires sidelink discovery gaps to do so, the gap pattern(s) as well as the concerned frequency, if different from the primary;

1> else if the UE initiates the procedure to report the system information parameters related to sidelink discovery of carriers other than the primary:

2> include discSysInfoReportFreqList and set it to report the system information parameter acquired from the cells on those carriers;

The UE shall submit the SidelinkUEInformation message to lower layers for transmission.

5.10.3 Sidelink communication monitoring

A UE capable of sidelink communication that is configured by upper layers to receive sidelink communication shall:

1> if the conditions for sidelink communication operation as defined in 5.10.1a are met:

2> if in coverage on the frequency used for sidelink communication, as defined in TS 36.304 [4], clause 11.4:

3> if the cell chosen for sidelink communication reception broadcasts SystemInformationBlockType18 including commRxPool:

4> configure lower layers to monitor sidelink control information and the corresponding data using the pool of resources indicated by commRxPool;

NOTE 1: If commRxPool includes one or more entries including rxParametersNCell, the UE may only monitor such entries if the associated PSS/SSS or SLSSIDs is detected. When monitoring such pool(s), the UE applies the timing of the concerned PSS/SSS or SLSS.

2> else (i.e. out of coverage on the sidelink carrier):

3> configure lower layers to monitor sidelink control information and the corresponding data using the pool of resources that were preconfigured (i.e. preconfigComm in SL-Preconfiguration defined in 9.3);

NOTE 2: The UE may monitor in accordance with the timing of the selected SyncRef UE, or if the UE does not have a selected SyncRef UE, based on the UE’s own timing.

5.10.4 Sidelink communication transmission

A UE capable of sidelink communication that is configured by upper layers to transmit non-relay related sidelink communication and has related data to be transmitted or a UE capable of relay related sidelink communication that is configured by upper layers to transmit relay related sidelink communications and satisfies the conditions for relay related sidelink communication specified in this clause shall:

1> if the conditions for sidelink communication operation as defined in 5.10.1a are met:

2> if in coverage on the frequency used for sidelink communication, as defined in TS 36.304 [4], clause 11.4:

3> if the UE is in RRC_CONNECTED and uses the PCell for sidelink communication:

4> if the UE is configured, by the current PCell/ the PCell in which physical layer problems or radio link failure was detected, with commTxResources set to scheduled:

5> if T310 or T311 is running; and if the PCell at which the UE detected physical layer problems or radio link failure broadcasts SystemInformationBlockType18 including commTxPoolExceptional; or

5> if T301 is running and the cell on which the UE initiated connection re-establishment broadcasts SystemInformationBlockType18 including commTxPoolExceptional:

6> configure lower layers to transmit the sidelink control information and the corresponding data using the pool of resources indicated by the first entry in commTxPoolExceptional;

5> else:

6> configure lower layers to request E-UTRAN to assign transmission resources for sidelink communication;

4> else if the UE is configured with commTxPoolNormalDedicated or commTxPoolNormalDedicatedExt:

5> if priorityList is included for the entries of commTxPoolNormalDedicated or commTxPoolNormalDedicatedExt:

6> configure lower layers to transmit the sidelink control information and the corresponding data using the one or more pools of resources indicated by commTxPoolNormalDedicated or commTxPoolNormalDedicatedExt i.e. indicate all entries of this field to lower layers;

5> else:

6> configure lower layers to transmit the sidelink control information and the corresponding data using the pool of resources indicated by the first entry in commTxPoolNormalDedicated;

3> else (i.e. sidelink communication in RRC_IDLE or on cell other than PCell in RRC_CONNECTED):

4> if the cell chosen for sidelink communication transmission broadcasts SystemInformationBlockType18:

5> if SystemInformationBlockType18 includes commTxPoolNormalCommon:

6> if priorityList is included for the entries of commTxPoolNormalCommon or commTxPoolNormalCommonExt:

7> configure lower layers to transmit the sidelink control information and the corresponding data using the one or more pools of resources indicated by commTxPoolNormalCommon and/or commTxPoolNormalCommonExt i.e. indicate all entries of these fields to lower layers;

6> else:

7> configure lower layers to transmit the sidelink control information and the corresponding data using the pool of resources indicated by the first entry in commTxPoolNormalCommon;

5> else if SystemInformationBlockType18 includes commTxPoolExceptional:

6> from the moment the UE initiates connection establishment until receiving an RRCConnectionReconfiguration including sl-CommConfig or until receiving an RRCConnectionRelease or an RRCConnectionReject;

7> configure lower layers to transmit the sidelink control information and the corresponding data using the pool of resources indicated by the first entry in commTxPoolExceptional;

2> else (i.e. out of coverage on sidelink carrier):

3> if priorityList is included for the entries of preconfigComm in SL-Preconfiguration defined in 9.3:

4> configure lower layers to transmit the sidelink control information and the corresponding data using the one or more pools of resources indicated preconfigComm i.e. indicate all entries of this field to lower layers and in accordance with the timing of the selected SyncRef UE, or if the UE does not have a selected SyncRef UE, based on the UEs own timing;

3> else:

4> configure lower layers to transmit the sidelink control information and the corresponding data using the pool of resources that were preconfigured i.e. indicated by the first entry in preconfigComm in SL-Preconfiguration defined in 9.3 and in accordance with the timing of the selected SyncRef UE, or if the UE does not have a selected SyncRef UE, based on the UEs own timing;

The conditions for relay related sidelink communication are as follows:

1> if the transmission concerns sidelink relay communication; and the UE is capable of sidelink relay or sidelink remote operation:

2> if the UE is in RRC_IDLE; and if the UE has a selected sidelink relay UE: configure lower layers to transmit the sidelink control information and the corresponding data using the resources, as specified previously in this clause, only if the following condition is met:

3> if the sidelink remote UE threshold conditions as specified in 5.10.11.5 are met; and if the UE configured lower layers with a pool of resources included in SystemInformationBlockType18 (i.e. commTxPoolNormalCommon, commTxPoolNormalCommonExt or commTxPoolExceptional); and commTxAllowRelayCommon is included in SystemInformationBlockType18;

2> if the UE is in RRC_CONNECTED: configure lower layers to transmit the sidelink control information and the corresponding data using the resources, as specified previously in this clause, only if the following condition is met:

3> if the UE configured lower layers with resources provided by dedicated signalling (i.e. commTxResources); and the UE is configured with commTxAllowRelayDedicated set to true;

5.10.5 Sidelink discovery monitoring

A UE capable of non-PS related sidelink discovery that is configured by upper layers to monitor non-PS related sidelink discovery announcements shall:

1> for each frequency the UE is configured to monitor non-PS related sidelink discovery announcements on, prioritising the frequencies included in discInterFreqList, if included in SystemInformationBlockType19:

2> if the PCell or the cell the UE is camping on indicates the pool of resources to monitor sidelink discovery announcements on by discRxResourcesInterFreq in discResourcesNonPS within discInterFreqList in SystemInformationBlockType19:

3> configure lower layers to monitor sidelink discovery announcements using the pool of resources indicated by discRxResourcesInterFreqin discResourcesNonPS within SystemInformationBlockType19;

2> else if the cell used for sidelink discovery monitoring broadcasts SystemInformationBlockType19:

3> configure lower layers to monitor sidelink discovery announcements using the pool of resources indicated by discRxPool in SystemInformationBlockType19;

2> if the UE is configured with discRxGapConfig and requires sidelink discovery gaps to monitor sidelink discovery announcements on the concerned frequency;

3> configure lower layers to monitor the concerned frequency using the sidelink discovery gaps indicated by discRxGapConfig;

2> else:

3> configure lower layers to monitor the concerned frequency without affecting normal operation;

A UE capable of PS related sidelink discovery that is configured by upper layers to monitor PS related sidelink discovery announcements shall:

1> if out of coverage on the frequency, as defined in TS 36.304 [4], clause 11.4:

2> configure lower layers to monitor sidelink discovery announcements using the pool of resources that were preconfigured (i.e. indicated by discRxPoolList within preconfigDisc in SL-Preconfiguration defined in 9.3);

1> else if configured by upper layers to monitor non-relay PS related discovery announcements; and if the PCell or the cell the UE is camping on indicates a pool of resources to monitor sidelink discovery announcements on by discRxResourcesInterFreq in discResourcesPS within discInterFreqList in SystemInformationBlockType19:

2> configure lower layers to monitor sidelink discovery announcements using the pool of resources indicated by discRxResourcesInterFreq in discResourcesPS in SystemInformationBlockType19;

1> else if configured by upper layers to monitor PS related sidelink discovery announcements; and if the cell used for sidelink discovery monitoring broadcasts SystemInformationBlockType19:

2> configure lower layers to monitor sidelink discovery announcements using the pool of resources indicated by discRxPoolPS in SystemInformationBlockType19;

1> if the UE is configured with discRxGapConfig and requires sidelink discovery gaps to monitor sidelink discovery announcements on the concerned frequency;

2> configure lower layers to monitor the concerned frequency using the sidelink discovery gaps indicated by discRxGapConfig;

1> else:

2> configure lower layers to monitor the concerned frequency without affecting normal operation;

NOTE 1: The requirement not to affect normal UE operation also applies for the acquisition of sidelink discovery related system and synchronisation information from inter-frequency cells.

NOTE 2: The UE is not required to monitor all pools simultaneously.

NOTE 3: It is up to UE implementation to decide whether a cell is sufficiently good to be used to monitor sidelink discovery announcements.

NOTE 4: If discRxPool, discRxPoolPS or discRxResourcesInterFreq includes one or more entries including rxParameters, the UE may only monitor such entries if the associated SLSSIDs are detected. When monitoring such pool(s) the UE applies the timing of the corresponding SLSS.

5.10.6 Sidelink discovery announcement

A UE capable of non-PS related sidelink discovery that is configured by upper layers to transmit non-PS related sidelink discovery announcements shall, for each frequency the UE is configured to transmit such announcements on:

NOTE: In case the configured resources are insufficient it is up to UE implementation to decide which sidelink discovery announcements to transmit.

1> if the frequency used to transmit sidelink discovery announcements concerns the serving frequency (RRC_IDLE) or primary frequency (RRC_CONNECTED):

2> if the UE’s serving cell (RRC_IDLE) or PCell (RRC_CONNECTED) is suitable as defined in TS 36.304 [4]:

3> if the UE is in RRC_CONNECTED (i.e. PCell is used for sidelink discovery announcement):

4> if the UE is configured with discTxResources set to scheduled:

5> configure lower layers to transmit the sidelink discovery announcement using the assigned resources indicated by scheduled in discTxResources;

4> else if the UE is configured with discTxPoolDedicated (i.e. discTxResources set to ue-Selected):

5> select an entry of the list of resource pool entries in discTxPoolDedicated and configure lower layers to use it to transmit the sidelink discovery announcements as specified in 5.10.6a;

3> else if T300 is not running (i.e. UE in RRC_IDLE, announcing via serving cell):

4> if SystemInformationBlockType19 of the serving cell includes discTxPoolCommon:

5> select an entry of the list of resource pool entries in discTxPoolCommon and configure lower layers to use it to transmit the sidelink discovery announcements as specified in 5.10.6a;

1> else if, for the frequency used to transmit sidelink discovery announcements on, the UE is configured with dedicated resources (i.e. with discTxResources-r12, if discTxCarrierFreq is included in discTxInterFreqInfo, or with discTxResources within discTxInfoInterFreqListAdd in discTxInterFreqInfo); and the conditions for non-PS related sidelink discovery operation as defined in 5.10.1c are met:

2> if the UE is configured with discTxResources set to scheduled:

3> configure lower layers to transmit the sidelink discovery announcement using the assigned resources indicated by scheduled in discTxResources;

2> else if the UE is configured with discTxResources set to ue-Selected:

3> select an entry of the list of resource pool entries in ue-Selected and configure lower layers to use it to transmit the sidelink discovery announcements as specified in 5.10.6a;

1> else if the frequency used to transmit sidelink discovery announcements on is included in discInterFreqList within SystemInformationBlockType19 of the serving cell/ PCell, and discTxResourcesInterFreq within discResourcesNonPS in the corresponding entry of discInterFreqList is set to discTxPoolCommon (i.e. serving cell/ PCell broadcasts pool of resources) and the conditions for non-PS related sidelink discovery operation as defined in 5.10.1c are met; or

1> else if discTxPoolCommon is included in SystemInformationBlockType19 acquired from cell selected on the sidelink discovery announcement frequency; and the conditions for non-PS related sidelink discovery operation as defined in 5.10.1c are met:

2> select an entry of the list of resource pool entries in discTxPoolCommon and configure lower layers to use it to transmit the sidelink discovery announcements as specified in 5.10.6a;

1> if the UE is configured with discTxGapConfig and requires sidelink discovery gaps to transmit sidelink discovery announcements on the concerned frequency;

2> configure lower layers to transmit on the concerned frequency using the sidelink discovery gaps indicated by discTxGapConfig,

1> else:

2> configure lower layers to transmit on the concerned frequency without affecting normal operation;

A UE capable of PS related sidelink discovery that is configured by upper layers to transmit PS related sidelink discovery announcements shall:

1> if out of coverage on the frequency used to transmit PS related sidelink discovery announcements as defined in TS 36.304 [4], clause 11.4, and the conditions for PS-related sidelink discovery operation as defined in 5.10.1b are met:

2> if configured by upper layers to transmit non-relay PS related sidelink discovery announcements; or

2> if the UE is selecting a sidelink relay UE/ has a selected sidelink relay UE:

3> configure lower layers to transmit sidelink discovery announcements using the pool of resources that were preconfigured and in accordance with the following;

4> randomly select, using a uniform distribution, an entry of preconfigDisc in SL-Preconfiguration defined in 9.3;

4> using the timing of the selected SyncRef UE, or if the UE does not have a selected SyncRef UE, based on the UEs own timing;

1> else if the frequency used to transmit sidelink discovery announcements concerns the serving frequency (RRC_IDLE) or primary frequency (RRC_CONNECTED) and the conditions for PS related sidelink discovery operation as defined in 5.10.1b are met:

2> if configured by upper layers to transmit non-relay PS related sidelink discovery announcements; or

2> if the UE is acting as sidelink relay UE; and if the UE is in RRC_IDLE; and if the sidelink relay UE threshold conditions as specified in 5.10.10.4 are met; or

2> if the UE is acting as sidelink relay UE; and if the UE is in RRC_CONNECTED; or

2> if the UE is selecting a sidelink relay UE / has a selected sidelink relay UE; and if the sidelink remote UE threshold conditions as specified in 5.10.11.5 are met:

3> if the UE is configured with discTxPoolPS-Dedicated; or

3> if the UE is in RRC_IDLE; and if discTxPoolPS-Common is included in SystemInformationBlockType19:

4> select an entry of the list of resource pool entries and configure lower layers to use it to transmit the sidelink discovery announcements as specified in 5.10.6a;

3> else if the UE is configured with discTxResourcesPS set to scheduled:

4> configure lower layers to transmit the sidelink discovery announcement using the assigned resources indicated by scheduled in discTxResourcesPS;

1> else if, for the frequency used to transmit sidelink discovery announcements on, the UE is configured with dedicated resources (i.e. with discTxResourcesPS in discTxInterFreqInfo within sl-DiscConfig); and the conditions for PS related sidelink discovery operation as defined in 5.10.1b are met:

2> if configured by upper layers to transmit non-relay PS related sidelink discovery announcements:

3> if the UE is configured with discTxResourcesPS set to scheduled:

4> configure lower layers to transmit the sidelink discovery announcement using the assigned resources indicated by scheduled in discTxResourcesPS;

3> else if the UE is configured with discTxResourcesPS set to ue-Selected:

4> select an entry of the list of resource pool entries in ue-Selected and configure lower layers to use it to transmit the sidelink discovery announcements as specified in 5.10.6a;

1> else if the frequency used to transmit sidelink discovery announcements on is included in discInterFreqList within SystemInformationBlockType19 of the serving cell/ PCell, while discTxResourcesInterFreq within discResourcesPS in the corresponding entry of discInterFreqList is set to discTxPoolCommon (i.e. serving cell/ PCell broadcasts pool of resources) and the conditions for PS related sidelink discovery operation as defined in 5.10.1b are met:

2> if configured by upper layers to transmit non-relay PS related sidelink discovery announcements:

3> select an entry of the list of resource pool entries in discTxPoolCommon and configure lower layers to use it to transmit the sidelink discovery announcements as specified in 5.10.6a;

1> else if discTxPoolPS-Common is included in SystemInformationBlockType19 acquired from cell selected on the sidelink discovery announcement frequency; and the conditions for PS related sidelink discovery operation as defined in 5.10.1b are met:

2> if configured by upper layers to transmit non-relay PS related sidelink discovery announcements:

3> select an entry of the list of resource pool entries in discTxPoolPS-Common and configure lower layers to use it to transmit the sidelink discovery announcements as specified in 5.10.6a;

1> if the UE is configured with discTxGapConfig and requires gaps to transmit sidelink discovery announcements on the concerned frequency;

2> configure lower layers to transmit on the concerned frequency using the gaps indicated by discTxGapConfig,

1> else:

2> configure lower layers to transmit on the concerned frequency without affecting normal operation;

5.10.6a Sidelink discovery announcement pool selection

A UE that is configured with a list of resource pool entries for sidelink discovery announcement transmission (i.e. by SL-DiscTxPoolList) shall:

1> if poolSelection is set to rsrpBased:

2> select a pool from the list of pools the UE is configured with for which the RSRP measurement of the reference cell selected as defined in 5.10.6b, after applying the layer 3 filter defined by quantityConfig as specified in 5.5.3.2, is in-between threshLow and threshHigh;

1> else:

2> randomly select, using a uniform distribution, a pool from the list of pools the UE is configured with;

1> configure lower layers to transmit the sidelink discovery announcement using the selected pool of resources;

NOTE 1: When performing resource pool selection based on RSRP, the UE uses the latest results of the available measurements used for cell reselection evaluation in RRC_IDLE/ for measurement report triggering evaluation in RRC_CONNECTED, which are performed in accordance with the performance requirements specified in TS 36.133 [16].

5.10.6b Sidelink discovery announcement reference carrier selection

A UE capable of sidelink discovery that is configured by upper layers to transmit sidelink discovery announcements shall:

1> for each frequency the UE is transmitting sidelink discovery announcements on, select a cell to be used as reference for synchronisation and DL measurements in accordance with the following:

2> if the frequency concerns the primary frequency:

3> use the PCell as reference;

2> else if the frequency concerns a secondary frequency:

3> use the concerned SCell as reference;

2> else if the UE is configured with discTxRefCarrierDedicated for the frequency:

3> use the cell indicated by this field as reference;

2> else if the UE is configured with refCarrierCommon for the frequency:

3> use the serving cell (RRC_IDLE)/ PCell (RRC_CONNECTED) as reference;

2> else:

3> use the DL frequency paired with the one used to transmit sidelink discovery announcements on as reference;

5.10.7 Sidelink synchronisation information transmission

5.10.7.1 General

Figure 5.10.7.1-1: Synchronisation information transmission for sidelink communication or V2X sidelink communication, in (partial) coverage

Figure 5.10.7.1-2: Synchronisation information transmission for sidelink communication or V2X sidelink communication / sidelink discovery, out of coverage

Figure 5.10.7.1-3: Synchronisation information transmission for sidelink discovery, in (partial) coverage

The purpose of this procedure is to provide synchronisation information to a UE. For sidelink discovery, the synchronisation information concerns a Sidelink Synchronisation Signal (SLSS) and, in case of PS related discovery, also timing information and some additional configuration parameters (i.e. the MasterInformationBlock-SL message), while for sidelink communication or V2X sidelink communication it concerns an SLSS and the MasterInformationBlock-SL or MasterInformationBlock-SL-V2X message. A UE transmits synchronisation information either when E-UTRAN configures it to do so by dedicated signalling (i.e. network based), or when not configured by dedicated signalling (i.e. UE based) and E-UTRAN broadcasts (in coverage) or pre-configures a threshold (out of coverage).

The synchronisation information transmitted by the UE may be derived from information/ signals received from E-UTRAN (in coverage) or received from a UE acting as synchronisation reference for the transmitting UE or received from GNSS. In the remainder, the UE acting as synchronisation reference is referred to as SyncRef UE.

5.10.7.2 Initiation

A UE capable of SLSS transmission shall, when transmitting sidelink discovery announcements in accordance with 5.10.6 and when the following conditions are met:

1> if in coverage on the frequency used for sidelink discovery, as defined in TS 36.304 [4], clause 11.4:

2> if in RRC_CONNECTED; and if networkControlledSyncTx is configured and set to on; or

2> if networkControlledSyncTx is not configured; and syncTxThreshIC is included in SystemInformationBlockType19; and the RSRP measurement of the reference cell, selected as defined in 5.10.6b, is below the value of syncTxThreshIC:

3> if the sidelink discovery announcements are not PS related; or if syncTxPeriodic is not included:

4> transmit SLSS on the frequency used for sidelink discovery in accordance with 5.10.7.3 and TS 36.211 [21];

3> else:

4> transmit SLSS on the frequency used for sidelink discovery in accordance with 5.10.7.3 and TS 36.211 [21];

4> transmit the MasterInformationBlock-SL message on the frequency used for sidelink discovery, in the same subframe as SLSS, and in accordance with 5.10.7.4;

1> else (i.e. out of coverage, PS):

2> if syncTxThreshOoC is included in the preconfigured sidelink parameters (i.e. SL-Preconfiguration defined in 9.3); and the UE has not selected SyncRef UE or the S-RSRP measurement result of the selected SyncRef UE is below the value of syncTxThreshOoC:

3> transmit SLSS on the frequency used for sidelink discovery in accordance with 5.10.7.3 and TS 36.211 [21];

3> transmit the MasterInformationBlock-SL message on the frequency used for sidelink discovery, in the same subframe as SLSS, and in accordance with 5.10.7.4;

A UE capable of sidelink communication that is configured by upper layers to transmit sidelink communication shall, irrespective of whether or not it has data to transmit:

1> if the conditions for sidelink communication operation as defined in 5.10.1a are met:

2> if in RRC_CONNECTED; and if networkControlledSyncTx is configured and set to on:

3> transmit SLSS in accordance with 5.10.7.3 and TS 36.211 [21];

3> transmit the MasterInformationBlock-SL message, in the same subframe as SLSS, and in accordance with 5.10.7.4;

A UE shall, when transmitting sidelink communication in accordance with 5.10.4 and when the following conditions are met:

1> if in coverage on the frequency used for sidelink communication, as defined in TS 36.304 [4], clause 11.4:

2> if the UE is in RRC_CONNECTED; and networkControlledSyncTx is not configured; and syncTxThreshIC is included in SystemInformationBlockType18; and the RSRP measurement of the cell chosen for sidelink communication transmission is below the value of syncTxThreshIC; or

2> if the UE is in RRC_IDLE; and syncTxThreshIC is included in SystemInformationBlockType18; and the RSRP measurement of the cell chosen for sidelink communication transmission is below the value of syncTxThreshIC:

3> transmit SLSS in accordance with 5.10.7.3 and TS 36.211 [21];

3> transmit the MasterInformationBlock-SL message, in the same subframe as SLSS, and in accordance with 5.10.7.4;

1> else (i.e. out of coverage):

2> if syncTxThreshOoC is included in the preconfigured sidelink parameters (i.e. SL-Preconfiguration defined in 9.3); and the UE has no selected SyncRef UE or the S-RSRP measurement result of the selected SyncRef UE is below the value of syncTxThreshOoC:

3> transmit SLSS in accordance with 5.10.7.3 and TS 36.211 [21];

3> transmit the MasterInformationBlock-SL message, in the same subframe as SLSS, and in accordance with 5.10.7.4;

A UE capable of V2X sidelink communication and SLSS/PSBCH transmission shall, when transmitting non-P2X related V2X sidelink communication in accordance with 5.10.13, and if the conditions for V2X sidelink communication operation as defined in 5.10.1d are met and when the following conditions are met:

1> if in coverage on the frequency used for V2X sidelink communication, as defined in TS 36.304 [4], clause 11.4; and has selected GNSS or the cell as synchronization reference as defined in 5.10.13.3; or

1> if out of coverage on the frequency used for V2X sidelink communication, as defined in TS 36.304 [4], clause 11.4, and the frequency used to transmit V2X sidelink communication is included in v2x-InterFreqInfoList in RRCConnectionReconfiguration or in v2x-InterFreqInfoList within SystemInformationBlockType21 or SystemInformationBlockType26 of the serving cell/ PCell; and has selected GNSS or the cell as synchronization reference as defined in 5.10.13.3:

2> if syncFreqList is not included in RRCConnectionReconfiguration nor in SystemInformationBlockType26; or

2> if syncFreqList is included in RRCConnectionReconfiguration or in SystemInformationBlockType26; and if none of the frequency(ies) selected as specified in TS 36.321 [6] is included in the syncFreqList or the concerned frequency is selected as the synchronisation carrier frequency in accordance with 5.10.8a; or

2> if syncFreqList and slss-TxMultiFreq are included in RRCConnectionReconfiguration or in SystemInformationBlockType26; and if the UE has selected a frequency other than the concerned frequency as the synchronisation carrier frequency; and if slss-TxDisabled corresponding to the concerned frequency is not configured in RRCConnectionReconfiguration; and if the concerned frequency has been selected for V2X sidelink communication transmission as specified in TS 36.321 [6] and is included in syncFreqList; and if UE is capable of SLSS/PSBCH transmission on the concerned frequency:

3> if in RRC_CONNECTED; and if networkControlledSyncTx is configured and set to on; or

3> if networkControlledSyncTx is not configured; and for the concerned frequency syncTxThreshIC is configured; and the RSRP measurement of the reference cell, selected as defined in 5.10.13.3, for V2X sidelink communication transmission is below the value of syncTxThreshIC:

4> transmit SLSS on the frequency used for V2X sidelink communication in accordance with 5.10.7.3 and TS 36.211 [21];

4> transmit the MasterInformationBlock-SL-V2X message on the frequency used for V2X sidelink communication, in the same subframe as SLSS, and in accordance with 5.10.7.4;

1> else:

2> for the frequency used for V2X sidelink communication, if syncOffsetIndicators is included in SL-V2X-Preconfiguration:

3> If syncFreqList is not included in SL-V2X-Preconfiguration; or

3> if syncFreqList is included in SL-V2X-Preconfiguration, and if none of the frequency(ies) selected as specified in TS 36.321 [6] is included in the syncFreqList or the concerned frequency is selected as the synchronisation carrier frequency in accordance with 5.10.8a; or

3> if syncFreqList and slss-TxMultiFreq are included in SL-V2X-Preconfiguration, and if the UE has selected a frequency other than the concerned frequency as the synchronisation carrier frequency; and if slss-TxDisabled corresponding to the concerned frequency is not configured in SL-V2X-Preconfiguration; and if the concerned frequency has been selected for V2X sidelink communication transmission as specified in TS 36.321 [6] and included in syncFreqList; and if the UE is capable of SLSS/PSBCH transmission on the frequency:

4> if syncTxThreshOoC is included in SL-V2X-Preconfiguration; and the UE is not directly synchronized to GNSS, and the UE has no selected SyncRef UE or the S-RSRP measurement result of the selected SyncRef UE is below the value of syncTxThreshOoC; or

4> if the UE selects GNSS as the synchronization reference source:

5> transmit SLSS in accordance with 5.10.7.3 and TS 36.211 [21];

5> transmit the MasterInformationBlock-SL-V2X message, in the same subframe as SLSS, and in accordance with 5.10.7.4;

NOTE 1: In the case of limited transmission capabilities on multiple carrier frequencies, when the UE is configured with syncFreqList, whether to transmit SLSS/PSBCH on a frequency, which is selected for V2X sidelink communication transmission as specified in TS 36.321 [6] and is other than the synchronisation carrier frequency, is up to UE implementation.

5.10.7.3 Transmission of SLSS

The UE shall select the SLSSID and the subframe in which to transmit SLSS as follows:

1> if triggered by sidelink discovery announcement and in coverage on the frequency used for sidelink discovery, as defined in TS 36.304 [4], clause 11.4:

2> select the SLSSID included in the entry of discSyncConfig included in the received SystemInformationBlockType19, that includes txParameters;

2> use syncOffsetIndicator corresponding to the selected SLSSID;

2> for each pool used for the transmission of discovery announcements (each corresponding to the selected SLSSID):

3> if a subframe indicated by syncOffsetIndicator corresponds to the first subframe of the discovery transmission pool;

4> if discTxGapConfig is configured and includes the concerned subframe; or the subframe is not used for regular uplink transmission:

5> select the concerned subframe;

3> else

4> if discTxGapConfig is configured and includes the concerned subframe; or the subframe is not used for regular uplink transmission:

5> select the subframe indicated by syncOffsetIndicator that precedes and which, in time domain, is nearest to the first subframe of the discovery transmission pool;

3> if the sidelink discovery announcements concern PS; and if syncTxPeriodic is included:

4> additionally select each subframe that periodically occurs 40 subframes after the selected subframe;

1> if triggered by sidelink communication and in coverage on the frequency used for sidelink communication, as defined in TS 36.304 [4], clause 11.4:

2> select the SLSSID included in the entry of commSyncConfig that is included in the received SystemInformationBlockType18 and includes txParameters;

2> use syncOffsetIndicator corresponding to the selected SLSSID;

2> if in RRC_CONNECTED; and if networkControlledSyncTx is configured and set to on:

3> select the subframe(s) indicated by syncOffsetIndicator;

2> else (when transmitting communication):

3> select the subframe(s) indicated by syncOffsetIndicator within the SC period in which the UE intends to transmit sidelink control information or data;

1> if triggered by V2X sidelink communication and in coverage on the frequency used for V2X sidelink communication, as defined in TS 36.304 [4], clause 11.4; or

1> if triggered by V2X sidelink communication, and out of coverage on the frequency used for V2X sidelink communication, and the concerned frequency is included in v2x-InterFreqInfoList in RRCConnectionReconfiguration or in v2x-InterFreqInfoList within SystemInformationBlockType21 of the serving cell/ PCell;

2> if the UE has selected GNSS as synchronization reference in accordance with 5.10.8.2:

3> select SLSSID 0;

3> use syncOffsetIndicator included in the entry of v2x-SyncConfig corresponding to the concerned frequency in v2x-InterFreqInfoList or within SystemInformationBlockType21, that includes txParameters and gnss-Sync;

3> select the subframe(s) indicated by syncOffsetIndicator;

2> if the UE has selected a cell as synchronization reference in accordance with 5.10.8.2:

3> select the SLSSID included in the entry of v2x-SyncConfig configured for the concerned frequency in v2x-InterFreqInfoList or within SystemInformationBlockType21, that includes txParameters and does not include gnss-Sync;

3> use syncOffsetIndicator corresponding to the selected SLSSID;

3> select the subframe(s) indicated by syncOffsetIndicator;

1> else if triggered by V2X sidelink communication and the UE has GNSS as the synchronization reference:

2> select SLSSID 0;

2> if syncOffsetIndicator3 is configured for the frequency used for V2X sidelink communication in SL-V2X-Preconfiguration:

3> select the subframe(s) indicated by syncOffsetIndicator3;

2> else:

3> select the subframe(s) indicated by syncOffsetIndicator1;

1> else:

2> select the synchronisation reference UE (i.e. SyncRef UE) as defined in 5.10.8;

2> if the UE has a selected SyncRef UE and inCoverage in the MasterInformationBlock-SL or MasterInformationBlock-SL-V2X message received from this UE is set to TRUE; or

2> if the UE has a selected SyncRef UE and inCoverage in the MasterInformationBlock-SL or MasterInformationBlock-SL-V2X message received from this UE is set to FALSE while the SLSS from this UE is part of the set defined for out of coverage, see TS 36.211 [21]:

3> select the same SLSSID as the SLSSID of the selected SyncRef UE;

3> select the subframe in which to transmit the SLSS according to the syncOffsetIndicator1 or syncOffsetIndicator2 included in the preconfigured sidelink parameters (i.e. preconfigSync in SL-Preconfiguration or v2x-CommPreconfigSync in SL-V2X-Preconfiguration defined in 9.3) corresponding to the concerned frequency, such that the subframe timing is different from the SLSS of the selected SyncRef UE;

2> else if the UE has a selected SyncRef UE and the SLSS from this UE was transmitted on the subframe indicated by syncOffsetIndicator3 that is included in the syncOffsetIndicators in SL-V2X-Preconfiguration, and is corresponding to the frequency used for V2X sidelink communication:

3> select SLSSID 169;

3> select the subframe(s) indicated by syncOffsetIndicator2;

2> else if the UE has a selected SyncRef UE:

3> select the SLSSID from the set defined for out of coverage having an index that is 168 more than the index of the SLSSID of the selected SyncRef UE, see TS 36.211 [21];

3> select the subframe in which to transmit the SLSS according to syncOffsetIndicator1 or syncOffsetIndicator2 included in the preconfigured sidelink parameters (i.e. preconfigSync in SL-Preconfiguration or v2x-CommPreconfigSync in SL-V2X-Preconfiguration defined in 9.3), such that the subframe timing is different from the SLSS of the selected SyncRef UE;

2> else (i.e. no SyncRef UE selected):

3> if triggered by V2X sidelink communication, randomly select, using a uniform distribution, an SLSSID from the set of sequences defined for out of coverage except SLSSID 168 and 169, see TS 36.211 [21];

3> else, randomly select, using a uniform distribution, an SLSSID from the set of sequences defined for out of coverage, see TS 36.211 [21];

3> select the subframe in which to transmit the SLSS according to the syncOffsetIndicator1 or syncOffsetIndicator2 (arbitrary selection between these) included in the preconfigured sidelink parameters (i.e. preconfigSync in SL-Preconfiguration or v2x-CommPreconfigSync in SL-V2X-Preconfiguration defined in 9.3);

5.10.7.4 Transmission of MasterInformationBlock-SL or MasterInformationBlock-SL-V2X message

The UE shall set the contents of the MasterInformationBlock-SL or MasterInformationBlock-SL-V2X message as follows:

1> if in coverage on the frequency used for the sidelink operation that triggered this procedure as defined in TS 36.304 [4], clause 11.4:

2> set inCoverage to TRUE;

2> set sl-Bandwidth to the value of ul-Bandwidth as included in the received SystemInformationBlockType2 of the cell chosen for the concerned sidelink operation;

2> if tdd-Config is included in the received SystemInformationBlockType1:

3> set subframeAssignmentSL to the value representing the same meaning as of subframeAssignment that is included in tdd-Config in the received SystemInformationBlockType1;

2> else:

3> set subframeAssignmentSL to none;

2> if triggered by sidelink communication; and if syncInfoReserved is included in an entry of commSyncConfig from the received SystemInformationBlockType18:

3> set reserved to the value of syncInfoReserved in the received SystemInformationBlockType18;

2> if triggered by sidelink discovery; and if syncInfoReserved is included in an entry of discSyncConfig from the received SystemInformationBlockType19:

3> set reserved to the value of syncInfoReserved in the received SystemInformationBlockType19;

2> if triggered by V2X sidelink communication; and if syncInfoReserved is included in an entry of v2x-SyncConfig from the received SystemInformationBlockType21 or SystemInformationBlockType26:

3> set reserved to the value of syncInfoReserved in the received SystemInformationBlockType21 or SystemInformationBlockType26;

2> else:

3> set all bits in reserved to 0;

1> else if out of coverage on the frequency used for V2X sidelink communication as defined in TS 36.304 [4], clause 11.4; and the concerned frequency is included in v2x-InterFreqInfoList in RRCConnectionReconfiguration or in v2x-InterFreqInfoList within SystemInformationBlockType21 or SystemInformationBlockType26 of the serving cell/ PCell:

2> set inCoverage to TRUE;

2> set sl-Bandwidth to the value of the corresponding field included in v2x-InterFreqInfoList;

2> set subframeAssignmentSL and reserved to the value of the corresponding field included in the preconfigured sidelink parameters (i.e. v2x-CommPreconfigGeneral in SL-V2X-Preconfiguration defined in 9.3);

1> else if out of coverage on the frequency used for V2X sidelink communication as defined in TS 36.304 [4], clause 11.4; and the UE selects GNSS timing as the synchronization reference source and syncOffsetIndicator3 is not included in SL-V2X-Preconfiguration:

2> set inCoverage to TRUE;

2> set sl-Bandwidth, subframeAssignmentSL and reserved to the value of the corresponding field included in the preconfigured sidelink parameters (i.e. v2x-CommPreconfigGeneral in SL-V2X-Preconfiguration defined in 9.3);

1> else if the UE has a selected SyncRef UE (as defined in 5.10.8) and if the SyncRef UE is selected on the concern frequency:

2> set inCoverage to FALSE;

2> set sl-Bandwidth, subframeAssignmentSL and reserved to the value of the corresponding field included in the received MasterInformationBlock-SL or MasterInformationBlock-SL-V2X;

1> else:

2> set inCoverage to FALSE;

2> set sl-Bandwidth, subframeAssignmentSL and reserved to the value of the corresponding field included in the preconfigured sidelink parameters (i.e. preconfigGeneral in SL-Preconfiguration or v2x-CommPreconfigGeneral in SL-V2X-Preconfiguration defined in 9.3);

1> set directFrameNumber and directSubframeNumber according to the subframe used to transmit the SLSS, as specified in 5.10.7.3;

1> submit the MasterInformationBlock-SL or MasterInformationBlock-SL-V2X message to lower layers for transmission upon which the procedure ends;

5.10.7.5 Void

5.10.8 Sidelink synchronisation reference

5.10.8.1 General

The purpose of this procedure is to select a synchronisation reference and used a.o. when transmitting sidelink communication, V2X sidelink communication, sidelink discovery or synchronisation information.

5.10.8.2 Selection and reselection of synchronisation reference

The UE shall:

1> if triggered by V2X sidelink communication, and in coverage on the frequency for V2X sidelink communication; or

1> if triggered by V2X sidelink communication, and out of coverage on the frequency for V2X sidelink communication, and the frequency used to transmit V2X sidelink communication is included in v2x-InterFreqInfoList in RRCConnectionReconfiguration or in v2x-InterFreqInfoList within SystemInformationBlockType21 or SystemInformationBlockType26 of the serving cell/ PCell:

2> If syncFreqList is not included in RRCConnectionReconfiguration nor in SystemInformationBlockType26; or

2> If syncFreqList is included in RRCConnectionReconfiguration or in SystemInformationBlockType26, and none of the frequency(ies) selected as specified in TS 36.321 [6] is included in the syncFreqList; or

2> If syncFreqList is included in RRCConnectionReconfiguration or in SystemInformationBlockType26, and no synchronisation carrier frequency is selected as specified in 5.10.8a:

3> if typeTxSync is configured for the concerned frequency and set to enb:

4> select a cell as the synchronization reference source as defined in 5.10.13.3;

3> else if typeTxSync for the concerned frequency is not configured or is set to gnss, and GNSS is reliable in accordance with TS 36.101 [42] and TS 36.133 [16]:

4> select GNSS as the synchronization reference source;

3> else (i.e., there is no GNSS which is reliable in accordance with TS 36.101 [42] and TS 36.133 [16]):

4> search SLSSID=0 on the concerned frequency to detect candidate SLSS, in accordance with TS 36.133 [16];

4> when evaluating the detected SLSS, apply layer 3 filtering as specified in 5.5.3.2 using the preconfigured filterCoefficient as defined in 9.3, before using the S-RSRP measurement results;

4> if the S-RSRP of the SyncRef UE identified by the detected SLSS exceeds the minimum requirement defined in TS 36.133 [16]:

5> select the SyncRef UE;

4> else (i.e., no SLSSID=0 detected):

5> select a cell as the synchronization reference source as defined in 5.10.13.3;

2> If syncFreqList is included in RRCConnectionReconfiguration or in SystemInformationBlockType26, and the UE has selected a synchronisation carrier frequency as specified in 5.10.8a:

3> consider the synchornisation reference source (i.e. eNB, GNSS or SyncRef UE) that is selected on the synchronisation carrier frequency as the synchronization reference;

1> else, if triggered by V2X sidelink communication, and out of coverage on the frequency for V2X sidelink communication, and for the frequency used for V2X sidelink communication, if syncPriority in SL-V2X-Preconfiguration is set to gnss and GNSS is reliable in accordance with TS 36.101 [42] and TS 36.133 [16]:

2> select GNSS as the synchronization reference source;

1> else, for the frequency used for sidelink communication, V2X sidelink communication or sidelink discovery, if out of coverage on that frequency as defined in TS 36.304 [4], clause 11.4:

2> if triggered by sidelink communication or sidelink discovery; or

2> if triggered by V2X sidelink communication, and syncFreqList is not included in SL-V2X-Preconfiguration; or

2> If triggered by V2X sidelink communication, and syncFreqList is included in SL-V2X-Preconfiguration, and none of the frequency(ies) selected as specified in TS 36.321 [6] is included in the syncFreqList; or

2> If triggered by V2X sidelink communication, and syncFreqList is included in SL-V2X-Preconfiguration, and no synchronisation carrier frequency is selected as specified in 5.10.8a:

3> perform a full search (i.e. covering all subframes and all possible SLSSIDs) to detect candidate SLSS, in accordance with TS 36.133 [16]

3> when evaluating the one or more detected SLSSIDs, apply layer 3 filtering as specified in 5.5.3.2 using the preconfigured filterCoefficient as defined in 9.3, before using the S-RSRP measurement results;

3> if the UE has selected a SyncRef UE:

4> if the S-RSRP of the strongest candidate SyncRef UE exceeds the minimum requirement TS 36.133 [16] by syncRefMinHyst and the strongest candidate SyncRef UE belongs to the same priority group as the current SyncRef UE and the S-RSRP of the strongest candidate SyncRef UE exceeds the S-RSRP of the current SyncRef UE by syncRefDiffHyst; or

4> if the S-RSRP of the candidate SyncRef UE exceeds the minimum requirement TS 36.133 [16] by syncRefMinHyst and the candidate SyncRef UE belongs to a higher priority group than the current SyncRef UE; or

4> if GNSS becomes reliable in accordance with TS 36.101 [42] and TS 36.133 [16], and GNSS belongs to a higher priority group than the current SyncRef UE; or

4> if the S-RSRP of the current SyncRef UE is less than the minimum requirement defined in TS 36.133 [16]:

5> consider no SyncRef UE to be selected;

3> if the UE has selected GNSS as the synchronization reference for V2X sidelink communication:

4> if the S-RSRP of the candidate SyncRef UE exceeds the minimum requirement defined in TS 36.133 [16] by syncRefMinHyst and the candidate SyncRef UE belongs to a higher priority group than GNSS; or

4> if GNSS becomes not reliable in accordance with TS 36.101 [42] and TS 36.133 [16]:

5> consider GNSS not to be selected;

3> if the UE has not selected a SyncRef UE and has not selected GNSS as synchronization reference source:

4> if not concerning V2X sidelink communication, and if the UE detects one or more SLSSIDs for which the S-RSRP exceeds the minimum requirement defined in TS 36.133 [16] by syncRefMinHyst and for which the UE received the corresponding MasterInformationBlock-SL message (candidate SyncRef UEs), select a SyncRef UE according to the following priority group order:

5> UEs of which inCoverage, included in the MasterInformationBlock-SL message received from this UE, is set to TRUE, starting with the UE with the highest S-RSRP result (priority group 1);

5> UEs of which SLSSID is part of the set defined for in coverage, starting with the UE with the highest S-RSRP result (priority group 2);

5> Other UEs, starting with the UE with the highest S-RSRP result (priority group 3);

4> for V2X sidelink communication, if the UE detects one or more SLSSIDs for which the S-RSRP exceeds the minimum requirement defined in TS 36.133 [16] by syncRefMinHyst and for which the UE received the corresponding MasterInformationBlock-SL-V2X message (candidate SyncRef UEs), or if the UE detects GNSS that is reliable in accordance with TS 36.101 [42] and TS 36.133 [16], select a synchronization reference according to the following priority group order:

5> if syncPriority corresponding to the concerned frequency in SL-V2X-Preconfiguration is set to enb:

6> UEs of which SLSSID is part of the set defined for in coverage, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to TRUE, starting with the UE with the highest S-RSRP result (priority group 1);

6> UE of which SLSSID is part of the set defined for in coverage, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to FALSE, starting with the UE with the highest S-RSRP result (priority group 2);

6> GNSS that is reliable in accordance with TS 36.101 [42] and TS 36.133 [16] (priority group 3);

6> UEs of which SLSSID is 0, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to TRUE, or of which SLSSID is 0 and SLSS is transmitted on subframes indicated by syncOffsetIndicator3, starting with the UE with the highest S-RSRP result (priority group 4);

6> UEs of which SLSSID is 0 and is not transmitted on subframes indicated by syncOffsetIndicator3, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to FALSE, starting with the UE with the highest S-RSRP result (priority group 5);

6> UEs of which SLSSID is 169, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to FALSE, starting with the UE with the highest S-RSRP result (priority group 5);

6> Other UEs, starting with the UE with the highest S-RSRP result (priority group 6);

5> if syncPriority corresponding to the concerned frequency in SL-V2X-Preconfiguration is set to gnss:

6> GNSS that is reliable in accordance with TS 36.101 [42] and TS 36.133 [16] (priority group 1);

6> UEs of which SLSSID is part of the set defined for in coverage, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to TRUE, starting with the UE with the highest S-RSRP result (priority group 2);

6> UEs of which SLSSID is 0, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to TRUE, or of which SLSSID is 0 and SLSS is transmitted on subframes indicated by syncOffsetIndicator3, starting with the UE with the highest S-RSRP result (priority group 2);

6> UE of which SLSSID is part of the set defined for in coverage, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to FALSE, starting with the UE with the highest S-RSRP result (priority group 3);

6> UEs of which SLSSID is 0 and is not transmitted on subframes indicated by syncOffsetIndicator3, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to FALSE, starting with the UE with the highest S-RSRP result (priority group 3);

6> UEs of which SLSSID is 169, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to FALSE, starting with the UE with the highest S-RSRP result (priority group 3);

6> Other UEs, starting with the UE with the highest S-RSRP result (priority group 4);

2> If triggered by V2X sidelink communication, and syncFreqList is included in SL-V2X-Preconfiguration, and the UE has selected a synchronisation carrier frequency as specified in 5.10.8a;

3> consider the synchornization reference source (i.e. eNB, GNSS or SyncRef UE) that selected on the synchronisation carrier frequency as the synchronization reference;

5.10.8a Selection and reselection of synchronisation carrier frequency

For the frequency(ies) which are in coverage for the UE as defined in TS 36.304 [4], clause 11.4 and which have been selected for V2X sidelink communication as specified in TS 36.321 [6], and/or for the frequency(ies) which are out of coverage for the UE and included in v2x-InterFreqInfoList within RRCConnectionReconfiguration or SystemInformationBlockType21 or SystemInformationBlockType26 of the serving cell/ PCell and which have been selected for V2X sidelink communication as specified in TS 36.321 [6], the UE capable of V2X sidelink communication and synchronisation carrier frequency selection shall:

1> If syncFreqList is included in RRCConnectionReconfiguration or in SystemInformationBlockType26, and includes at least one of the concerned frequency(ies):

2> if no synchronisation carrier frequency is selected:

3> If typeTxSync is configured for the concerned frequency(ies) and set to enb; or

3> if typeTxSync for the concerned frequency(ies) is not configured or is set to gnss, and GNSS is reliable in accordance with TS 36.101 [42] and TS 36.133 [16]:

4> select one frequency from the concerned frequency(ies) which are included in syncFreqList as the synchronisation carrier frequency.

3> else (i.e., there is no GNSS which is reliable in accordance with TS 36.101 [42] and TS 36.133 [16]):

4> select the synchronisation reference source(s) on the concerned frequency(ies) which are included in syncFreqList according to 5.10.8.2:

4> if SyncRef UE(s) with SLSSID=0 is detected on at least one frequency from the concerned frequency(ies):

5> select one frequency from the concerned frequency(ies) with the SyncRef UE(s) with SLSSID=0 detected as the synchronisation carrier frequency;

4> else (i.e., no SLSSID=0 detected and UE selects a cell as the synchronisation reference source):

5> select one frequency from the concerned frequencies which are included in syncFreqList as the synchronisation carrier frequency;

2> else (i.e. the synchronisation carrier frequency is selected):

3> If the UE selects GNSS as the synchronisation reference source, and GNSS is unreliable in accordance with TS 36.101 [42] and TS 36.133 [16]; or

3> If the UE selects a cell as the synchronisation reference source, and the cell cannot fulfil the S criterion in accordance with TS 36.304 [4]; or

3> If the UE selects a SyncRef UE and the S-RSRP of the current SyncRef UE is less than the minimum requirement defined in TS 36.133 [16]; or

3> If the synchronisation carrier frequency is not selected for V2X sidelink communication as specified in TS 36.321 [6]:

4> consider no synchronisation carrier frequency is selected;

For the frequency(ies) which are out of coverage for the UE and not included in v2x-InterFreqInfoList within RRCConnectionReconfiguration nor SystemInformationBlockType21 nor SystemInformationBlockType26 of the serving cell/ PCell and which have been selected for V2X sidelink carrier communication as specified in TS 36.321 [6], the UE capable of V2X sidelink communication and selection of synchronisation carrier frequency selection shall:

1> If syncFreqList is included in SL-V2X-Preconfiguration, and at least one of the concerned frequency(ies) is included in syncFreqList:

2> if no synchronisation carrier frequency is selected:

3> if syncPriority in SL-V2X-Preconfiguration is set to gnss and GNSS is reliable in accordance with TS 36.101 [42] and TS 36.133 [16]:

4> select one frequency from the concerned frequency(ies) which are included in syncFreqList as the synchronisation carrier frequency.

3> else:

4> select the synchronisation reference source(s) on the concerned frequency(ies) which are included in SyncFreqList according to 5.10.8.2;

4> select the frequency with the highest synchronisation reference source priority as the synchronisation carrier frequency, according to the following priority gourp order:

5> if syncPriority corresponding to the concerned frequency(ies) in SL-V2X-Preconfiguration is set to enb:

6> the frequency(ies) with SyncRef UE of which SLSSID is part of the set defined for in coverage, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to TRUE (priority group 1);

6> the frequency(ies) with SyncRef UE of which SLSSID is part of the set defined for in coverage, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to FALSE (priority group 2);

6> the frequency(ies) using GNSS as synchronisation reference source (priority group 3);

6> the frequency(ies) with SyncRef UE of which SLSSID is 0, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to TRUE, or of which SLSSID is 0 and SLSS is transmitted on subframes indicated by syncOffsetIndicator3 (priority group 4);

6> the frequency(ies) with SyncRef UE of which SLSSID is 0 and is not transmitted on subframes indicated by syncOffsetIndicator3, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to FALSE (priority group 5);

6> the frequency(ies) with SyncRef UE of which SLSSID is 169, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to FALSE (priority group 5);

6> the frequency(ies) with other SyncRef UE (priority group 6);

5> if syncPriority corresponding to the concerned frequency(ies) in SL-V2X-Preconfiguration is set to gnss:

6> the frequency(ies) with SyncRef UE of which SLSSID is part of the set defined for in coverage, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to TRUE (priority group 1);

6> the frequency(ies) with SyncRef UE of which SLSSID is 0, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to TRUE, or of which SLSSID is 0 and SLSS is transmitted on subframes indicated by syncOffsetIndicator3 (priority group 1);

6> the frequency(ies) with SyncRef UE of which SLSSID is part of the set defined for in coverage, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to FALSE (priority group 2);

6> the frequency(ies) with SyncRef UE of which SLSSID is 0 and is not transmitted on subframes indicated by syncOffsetIndicator3, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to FALSE (priority group 2);

6> the frequency(ies) with SyncRef UE of which SLSSID is 169, and inCoverage, included in the MasterInformationBlock-SL-V2X message received from this UE, is set to FALSE (priority group 2);

6> the frequency(ies) with other SyncRef UE (priority group 3);

2> else (i.e. the synchronisation carrier frequency is selected):

3> If the UE selects GNSS as the synchronisation reference source, and GNSS is unreliable in accordance with TS 36.101 [42] and TS 36.133 [16]; or

3> If the UE selects a SyncRef UE and the S-RSRP of the current SyncRef UE is less than the minimum requirement defined in TS 36.133 [16]; or

3> If the synchronisation carrier frequency is not selected for V2X sidelink communication as specified in TS 36.321 [6]:

4> consider no synchronisation carrier frequency is selected;

NOTE 1: If more than one selected carrier frequencies satisfy the condition as the synchronisation carrier frequency for V2X sidelink communication, how to select one synchronisation carrier frequency is up to UE implementation.

NOTE 2: All concerned carrier frequency(ies) have the same typeTxSync and syncPriority configured.

5.10.9 Sidelink common control information

5.10.9.1 General

The sidelink common control information is carried by a single message, the MasterInformationBlock-SL (MIB-SL) message for sidelink discovery and sidelink communication or the MasterInformationBlock-SL-V2X (MIB-SL-V2X) message for V2X sidelink communication. The MIB-SL or MIB-SL-V2X includes timing information as well as some configuration parameters and is transmitted via SL-BCH.

The MIB-SL for sidelink discovery and sidelink communication uses a fixed schedule with a periodicity of 40 ms without repetitions. In particular, the MIB-SL is scheduled in subframes indicated by syncOffsetIndicator-r12 i.e. for which (10*DFN + subframe number) mod 40 = syncOffsetIndicator-r12.

The MIB-SL-V2X for V2X sidelink communication uses a fixed schedule with a periodicity of 160 ms without repetitions. In particular, the MIB-SL-V2X is scheduled in subframes indicated by SL-OffsetIndicatorSync i.e. for which (10*DFN + subframe number) mod 160 = SL-OffsetIndicatorSync.

The sidelink common control information may change at any transmission i.e. neither a modification period nor a change notification mechanism is used.

A UE configured to receive or transmit sidelink communication or PS related sidelink discovery shall:

1> if the UE has a selected SyncRef UE, as specified in 5.10.8.2:

2> ensure having a valid version of the MasterInformationBlock-SL message of that SyncRefUE;

A UE configured to receive or transmit V2X sidelink communication shall:

1> if the UE has a selected SyncRef UE, as specified in 5.10.8.2:

2> ensure having a valid version of the MasterInformationBlock-SL-V2X message of that SyncRefUE;

5.10.9.2 Actions related to reception of MasterInformationBlock-SL/ MasterInformationBlock-SL-V2X message

Upon receiving MasterInformationBlock-SL or MasterInformationBlock-SL-V2X, the UE shall:

1> apply the values of sl-Bandwidth, subframeAssignmentSL, directFrameNumber and directSubframeNumber included in the received MasterInformationBlock-SL or MasterInformationBlock-SL-V2X message;

5.10.10 Sidelink relay UE operation

5.10.10.1 General

This procedure is used by a UE supporting sidelink relay UE operation and involves evaluation of the AS-layer conditions that need to be met in order for upper layers to configure a sidelink relay UE to receive/ transmit relay related PS sidelink discovery/ relay related sidelink communication. The AS-layer conditions merely comprise of being configured with radio resources that can be used for transmission.

A UE that fulfils the criteria specified in 5.10.10.2 and 5.10.10.3 and that is configured by higher layers accordingly is acting as a sidelink relay UE.

5.10.10.2 AS-conditions for relay related sidelink communication transmission by sidelink relay UE

A UE capable of sidelink relay UE operation shall inform upper layers that it is configured with radio resources that can be used for relay related sidelink communication transmission if the following conditions are met:

1> if in RRC_CONNECTED; and if the UE is configured with commTxResources; and the UE is configured with commTxAllowRelayDedicated set to true;

5.10.10.3 AS-conditions for relay PS related sidelink discovery transmission by sidelink relay UE

A UE capable of sidelink relay UE operation shall inform upper layers that it is configured with radio resources that can be used for relay PS related sidelink discovery transmission if the following conditions are met:

1> if in RRC_IDLE; and if the UE’s serving cell is suitable as defined in TS 36.304 [4]; and if SystemInformationBlockType19 includes discConfigPS including discTxPoolPS-Common and discConfigRelay; and if the sidelink relay UE threshold conditions as specified in 5.10.10.4 are met;

1> else if in RRC_CONNECTED; and if discTxResourcesPS is configured;

5.10.10.4 Sidelink relay UE threshold conditions

A UE capable of sidelink relay UE operation shall:

1> if the threshold conditions specified in this clause were not met:

2> if neither threshHigh nor threshLow is included in relayUE-Config within SystemInformationBlockType19:

3> consider the threshold conditions to be met (entry);

2> else if threshHigh is not included in relayUE-Config within SystemInformationBlockType19; or the RSRP measurement of the PCell, or the cell on which the UE camps, is below threshHigh by hystMax (also included within relayUE-Config); and

2> if threshLow is not included in relayUE-Config within SystemInformationBlockType19; or the RSRP measurement of the PCell, or the cell on which the UE camps, is above threshLow by hystMin (also included within relayUE-Config):

3> consider the threshold conditions to be met (entry);

1> else:

2> if threshHigh is included in relayUE-Config within SystemInformationBlockType19; and the RSRP measurement of the PCell, or the cell on which the UE camps, is above threshHigh (also included within relayUE-Config); or

2> if threshLow is included in relayUE-Config within SystemInformationBlockType19; and the RSRP measurement of the PCell, or the cell on which the UE camps, is below threshLow (also included within relayUE-Config);

3> consider the threshold conditions not to be met (leave);

5.10.11 Sidelink remote UE operation

5.10.11.1 General

This procedure is used by a UE supporting sidelink remote UE operation and involves evaluation of the AS-layer conditions that need to be met in order for upper layers to configure a sidelink remote UE to receive/ transmit relay related sidelink PS discovery/ relay related sidelink communication. The AS-layer conditions merely comprise of being configured with radio resources that can be used for transmission, as well as whether or not having a selected sidelink relay UE.

5.10.11.2 AS-conditions for relay related sidelink communication transmission by sidelink remote UE

A UE capable of sidelink remote UE operation shall inform upper layers whether it is configured with radio resources that can be used for relay related sidelink communication transmission if the following conditions are met:

1> if the UE is out of coverage; and is preconfigured with SL-Preconfiguration including discTxPoolList and preconfigRelay;

1> else if in RRC_IDLE; and if the UE’s serving cell is suitable as defined in TS 36.304 [4]; and if SystemInformationBlockType18 includes commTxPoolNormalCommon and commTxAllowRelayCommon; and if SystemInformationBlockType19 includes discConfigRelay; and if the sidelink remote UE threshold conditions as specified in 5.10.11.5 are met;

1> else if in RRC_CONNECTED; and if the UE is configured with commTxResources; and the UE is configured with commTxAllowRelayDedicated set to true;

5.10.11.3 AS-conditions for relay PS related sidelink discovery transmission by sidelink remote UE

A UE capable of sidelink remote UE operation shall inform upper layers whether it is configured with radio resources that can be used for relay PS related sidelink discovery transmission if the following conditions are met:

1> if the UE is out of coverage; and is preconfigured with SL-Preconfiguration including discTxPoolList and preconfigRelay;

1> else if in RRC_IDLE; and if the UE’s serving cell is suitable as defined in TS 36.304 [4]; and if SystemInformationBlockType19 includes discConfigPS including discTxPoolPS-Common and discConfigRelay; and if the sidelink remote UE threshold conditions as specified in 5.10.11.5 are met;

1> else if in RRC_CONNECTED; and if discTxResourcesPS is configured;

5.10.11.4 Selection and reselection of sidelink relay UE

A UE capable of sidelink remote UE operation that is configured by upper layers to search for a sidelink relay UE shall:

1> if out of coverage on the frequency used for sidelink communication, as defined in TS 36.304 [4], clause 11.4; or

1> if the serving frequency is used for sidelink communication and the RSRP measurement of the cell on which the UE camps (RRC_IDLE)/ the PCell (RRC_CONNECTED) is below threshHigh within remoteUE-Config :

2> search for candidate sidelink relay UEs, in accordance with TS 36.133 [16]

2> when evaluating the one or more detected sidelink relay UEs, apply layer 3 filtering as specified in 5.5.3.2 across measurements that concern the same ProSe Relay UE ID and using the filterCoefficient in SystemInformationBlockType19 (in coverage) or the preconfigured filterCoefficient as defined in 9.3(out of coverage), before using the SD-RSRP measurement results;

NOTE 1: The details of the interaction with upper layers are up to UE implementation.

2> if the UE does not have a selected sidelink relay UE:

3> select a candidate sidelink relay UE which SD-RSRP exceeds q-RxLevMin included in either reselectionInfoIC (in coverage) or reselectionInfoOoC (out of coverage) by minHyst;

2> else if SD-RSRP of the currently selected sidelink relay UE is below q-RxLevMin included in either reselectionInfoIC (in coverage) or reselectionInfoOoC (out of coverage); orif upper layers indicate not to use the currently selected sidelink relay: (i.e. sidelink relay UE reselection):

3> select a candidate sidelink relay UE which SD-RSRP exceeds q-RxLevMin included in either reselectionInfoIC (in coverage) or reselectionInfoOoC (out of coverage) by minHyst;

2> else if the UE did not detect any candidate sidelink relay UE which SD-RSRP exceeds q-RxLevMin included in either reselectionInfoIC (in coverage) or reselectionInfoOoC (out of coverage) by minHyst:

3> consider no sidelink relay UE to be selected;

NOTE 2: The UE may perform sidelink relay UE reselection in a manner resulting in selection of the sidelink relay UE, amongst all candidate sidelink relay UEs meeting higher layer criteria, that has the best radio link quality. Further details, including interaction with upper layers, are up to UE implementation.

5.10.11.5 Sidelink remote UE threshold conditions

A UE capable of sidelink remote UE operation shall:

1> if the threshold conditions specified in this clause were not met:

2> if threshHigh is not included in remoteUE-Config within SystemInformationBlockType19; or

2> if threshHigh is included in remoteUE-Config within SystemInformationBlockType19; and the RSRP measurement of the PCell, or the cell on which the UE camps, is below threshHigh by hystMax (also included within remoteUE-Config):

3> consider the threshold conditions to be met (entry);

1> else:

2> if threshHigh is included in remoteUE-Config within SystemInformationBlockType19; and the RSRP measurement of the PCell, or the cell on which the UE camps, is above threshHigh (also included within remoteUE-Config):

3> consider the threshold conditions not to be met (leave);

5.10.12 V2X sidelink communication monitoring

A UE capable of V2X sidelink communication that is configured by upper layers to receive V2X sidelink communication shall:

1> if the conditions for sidelink operation as defined in 5.10.1d are met:

2> if in coverage on the frequency used for V2X sidelink communication, as defined in TS 36.304 [4], clause 11.4:

3> if the frequency used to receive V2X sidelink communication is included in v2x-InterFreqInfoList within RRCConnectionReconfiguration or in v2x-InterFreqInfoList within SystemInformationBlockType21 or SystemInformationBlockType26 of the serving cell/Pcell, and v2x-CommRxPool is included in SL-V2X-InterFreqUE-Config within v2x-UE-ConfigList in the entry of v2x-InterFreqInfoList for the concerned frequency:

4> configure lower layers to monitor sidelink control information and the corresponding data using the pool of resources indicated in v2x-CommRxPool;

3> else:

4> if the cell chosen for V2X sidelink communication reception broadcasts SystemInformationBlockType21 including v2x-CommRxPool in sl-V2X-ConfigCommon or,

4> if the UE is configured with v2x-CommRxPool included in mobilityControlInfoV2X in RRCConnectionReconfiguration:

5> configure lower layers to monitor sidelink control information and the corresponding data using the pool of resources indicated in v2x-CommRxPool;

2> else (i.e. out of coverage on the frequency used for V2X sidelink communication, as defined in TS 36.304 [4], clause 11.4):

3> if the frequency used to receive V2X sidelink communication is included in v2x-InterFreqInfoList within RRCConnectionReconfiguration or in v2x-InterFreqInfoList within SystemInformationBlockType21 or SystemInformationBlockType26 of the serving cell/PCell, and v2x-CommRxPool is included in SL-V2X-InterFreqUE-Config within v2x-UE-ConfigList in the entry of v2x-InterFreqInfoList for the concerned frequency:

4> configure lower layers to monitor sidelink control information and the corresponding data using the pool of resources indicated in v2x-CommRxPool;

3> else:

4> configure lower layers to monitor sidelink control information and the corresponding data using the pool of resources that were preconfigured (i.e. v2x-CommRxPoolList in SL-V2X-Preconfiguration defined in 9.3);

5.10.13 V2X sidelink communication transmission

5.10.13.1 Transmission of V2X sidelink communication

A UE capable of V2X sidelink communication that is configured by upper layers to transmit V2X sidelink communication and has related data to be transmitted shall:

1> if the conditions for sidelink operation as defined in 5.10.1d are met:

2> if in coverage on the frequency used for V2X sidelink communication as defined in TS 36.304 [4], clause 11.4; or

2> if the frequency used to transmit V2X sidelink communication is included in v2x-InterFreqInfoList in RRCConnectionReconfiguration or in v2x-InterFreqInfoList within SystemInformationBlockType21 or SystemInformationBlockType26:

3> if the UE is in RRC_CONNECTED and uses the PCell or the frequency included in v2x-InterFreqInfoList in RRCConnectionReconfiguration for V2X sidelink communication:

4> if the UE is configured, by the current PCell with commTxResources set to scheduled:

5> if T310 or T311 is running; and if the PCell at which the UE detected physical layer problems or radio link failure broadcasts SystemInformationBlockType21 including v2x-CommTxPoolExceptional in sl-V2X-ConfigCommon, or v2x-CommTxPoolExceptional is included in v2x-InterFreqInfoList for the concerned frequency in SystemInformationBlockType21 or SystemInformationBlockType26 or RRCConnectionReconfiguration; or

5> if T301 is running and the cell on which the UE initiated connection re-establishment broadcasts SystemInformationBlockType21 including v2x-CommTxPoolExceptional in sl-V2X-ConfigCommon, or v2x-CommTxPoolExceptional is included in v2x-InterFreqInfoList for the concerned frequency in SystemInformationBlockType21 or SystemInformationBlockType26; or

5> if T304 is running and the UE is configured with v2x-CommTxPoolExceptional included in mobilityControlInfoV2X in RRCConnectionReconfiguration or in v2x-InterFreqInfoList for the concerned frequency in RRCConnectionReconfiguration:

6> configure lower layers to transmit the sidelink control information and the corresponding data based on random selection using the pool of resources indicated by v2x-CommTxPoolExceptional as defined in TS 36.321 [6];

5> else:

6> configure lower layers to request E-UTRAN to assign transmission resources for V2X sidelink communication;

4> else if the UE is configured with v2x-CommTxPoolNormalDedicated or v2x-CommTxPoolNormal or p2x-CommTxPoolNormal in the entry of v2x-InterFreqInfoList for the concerned frequency in sl-V2X-ConfigDedicated in RRCConnectionReconfiguration:

5> if the UE is configured to transmit non-P2X related V2X sidelink communication and a result of sensing on the resources configured in v2x-CommTxPoolNormalDedicated or v2x-CommTxPoolNormal in the entry of v2x-InterFreqInfoList for the concerned frequency in RRCConnectionReconfiguration is not available in accordance with TS 36.213 [23]; or

5> if the UE is configured to transmit P2X related V2X sidelink communication and selects to use partial sensing according to 5.10.13.1a, and a result of partial sensing on the resources configured in v2x-CommTxPoolNormalDedicated or p2x-CommTxPoolNormal in the entry of v2x-InterFreqInfoList for the concerned frequency in RRCConnectionReconfiguration is not available in accordance with TS 36.213 [23]:

6> if v2x-CommTxPoolExceptional is included in mobilityControlInfoV2X in RRCConnectionReconfiguration (i.e., handover case); or

6> if v2x-CommTxPoolExceptional is included in the entry of v2x-InterFreqInfoList for the concerned frequency in RRCConnectionReconfiguration; or

6> if the PCell broadcasts SystemInformationBlockType21 including v2x-CommTxPoolExceptional in sl-V2X-ConfigCommon or v2x-CommTxPoolExceptional in v2x-InterFreqInfoList for the concerned frequency or broadcasts SystemInformationBlockType26 including v2x-CommTxPoolExceptional in v2x-InterFreqInfoList for the concerned frequency:

7> configure lower layers to transmit the sidelink control information and the corresponding data based on random selection using the pool of resources indicated by v2x-CommTxPoolExceptional as defined in TS 36.321 [6];

5> else if the UE is configured to transmit P2X related V2X sidelink communication:

6> select a resource pool according to 5.10.13.2;

6> perform P2X related V2X sidelink communication according to 5.10.13.1a;

5> else if the UE is configured to transmit non-P2X related V2X sidelink communication:

6> configure lower layers to transmit the sidelink control information and the corresponding data based on sensing (as defined in TS 36.321 [6] and TS 36.213 [23]) using one of the resource pools indicated by v2x-commTxPoolNormalDedicated or v2x-CommTxPoolNormal in the entry of v2x-InterFreqInfoList for the concerned frequency, which is selected according to 5.10.13.2;

3> else:

4> if the cell chosen for V2X sidelink communication transmission broadcasts SystemInformationBlockType21 or SystemInformationBlockType26:

5> if the UE is configured to transmit non-P2X related V2X sidelink communication, and if SystemInformationBlockType21 includes v2x-CommTxPoolNormalCommon or v2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency, or SystemInformationBlockType26 includes v2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency, and if a result of sensing on the resources configured in v2x-CommTxPoolNormalCommon or v2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency is available in accordance with TS 36.213 [23]:

6> configure lower layers to transmit the sidelink control information and the corresponding data based on sensing (as defined in TS 36.321 [6] and TS 36.213 [23]) using one of the resource pools indicated by v2x-CommTxPoolNormalCommon or v2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency, which is selected according to 5.10.13.2;

5> else if the UE is configured to transmit P2X related V2X sidelink communication, and if SystemInformationBlockType21 includes p2x-CommTxPoolNormalCommon or p2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency, or SystemInformationBlockType26 includes p2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency, and if the UE selects to use random selection according to 5.10.13.1a, or selects to use partial sensing according to 5.10.13.1a and a result of partial sensing on the resources configured in p2x-CommTxPoolNormalCommon or p2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency is available in accordance with TS 36.213 [23]:

6> select a resource pool from p2x-CommTxPoolNormalCommon or p2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency according to 5.10.13.2, but ignoring zoneConfig in SystemInformationBlockType21 or SystemInformationBlockType26;

6> perform P2X related V2X sidelink communication according to 5.10.13.1a;

5> else if SystemInformationBlockType21 includes v2x-CommTxPoolExceptional in sl-V2X-ConfigCommon or v2x-CommTxPoolExceptional in v2x-InterFreqInfoList for the concerned frequency, or SystemInformationBlockType26 includes v2x-CommTxPoolExceptional in v2x-InterFreqInfoList for the concerned frequency:

6> from the moment the UE initiates connection establishment until receiving an RRCConnectionReconfiguration including sl-V2X-ConfigDedicated, or until receiving an RRCConnectionRelease or an RRCConnectionReject; or

6> if the UE is in RRC_IDLE and a result of sensing on the resources configured in v2x-CommTxPoolNormalCommon or v2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency in Systeminformationblocktype21 or v2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency in Systeminformationblocktype26 is not available in accordance with TS 36.213 [23]; or

6> if the UE is in RRC_IDLE and UE selects to use partial sensing according to 5.10.13.1a and a result of partial sensing on the resources configured in p2x-CommTxPoolNormalCommon or p2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency in Systeminformationblocktype21 or v2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency in Systeminformationblocktype26 is not available in accordance with TS 36.213 [23]:

7> configure lower layers to transmit the sidelink control information and the corresponding data based on random selection (as defined in TS 36.321 [6]) using the pool of resources indicated in v2x-CommTxPoolExceptional;

2> else:

3> configure lower layers to transmit the sidelink control information and the corresponding data based on sensing (as defined in TS 36.321 [6] and TS 36.213 [23]) using one of the resource pools indicated by v2x-CommTxPoolList in SL-V2X-Preconfiguration in case of non-P2X related V2X sidelink communication, which is selected according to 5.10.13.2, or using one of the resource pools indicated by p2x-CommTxPoolList in SL-V2X-Preconfiguration in case of P2X related V2X sidelink communication, which is selected according to 5.10.13.2, and in accordance with the timing of the selected reference as defined in 5.10.8;

The UE capable of non-P2X related V2X sidelink communication that is configured by upper layers to transmit V2X sidelink communication shall perform sensing on all pools of resources which may be used for transmission of the sidelink control information and the corresponding data. The pools of resources are indicated by SL-V2X-Preconfiguration, v2x-CommTxPoolNormalCommon, v2x-CommTxPoolNormalDedicated in sl-V2X-ConfigDedicated, or v2x-CommTxPoolNormal in v2x-InterFreqInfoList for the concerned frequency, as configured above.

5.10.13.1a Transmission of P2X related V2X sidelink communication

A UE configured to transmit P2X related V2X sidelink communication shall:

1> if partialSensing is included and randomSelection is not included in resourceSelectionConfigP2X of the pool selected; or

1> if both partialSensing and randomSelection are included in resourceSelectionConfigP2X of the pool selected, and the UE selects to use partial sensing:

2> configure lower layers to transmit the sidelink control information and the corresponding data based on partial sensing (as defined in TS 36.321 [6] and TS 36.213 [23]) using the selected resource pool, if the UE supports partial sensing;

1> if partialSensing is not included and randomSelection is included in resourceSelectionConfigP2X of the pool selected.

2> configure lower layers to transmit the sidelink control information and the corresponding data based on random selection (as defined in TS 36.321 [6] and TS 36.213 [23]) using the selected resource pool;

1> if both partialSensing and randomSelection is included in resourceSelectionConfigP2X of the pool selected, and the UE selects to use random selection:

2> configure lower layers to transmit the sidelink control information and the corresponding data based on random selection using the selected resource pool and indicates to lower layers that transmissions of multiple MAC PDUs are allowed (as defined in TS 36.321 [6] and TS 36.213 [23]).

NOTE: If both partialSensing and randomSelection is included in resourceSelectionConfigP2X of the pool selected, the selection between partial sensing and random selection is left to UE implementation.

5.10.13.2 V2X sidelink communication transmission pool selection

For a frequency used for V2X sidelink communication, if zoneConfig is not ignored as specified in 5.10.13.1, the UE configured by upper layers for V2X sidelink communication shall only use the pool which corresponds to geographical coordinates of the UE, if zoneConfig is included in SystemInformationBlockType21 or SystemInformationBlockType26 of the serving cell (RRC_IDLE)/ PCell (RRC_CONNECTED) or in RRCConnectionReconfiguration for the concerned frequency, and the UE is configured to use resource pools provided by RRC signalling for the concerned frequency; or if zoneConfig is included in SL-V2X-Preconfiguration for the concerned frequency, and the UE is configured to use resource pools in SL-V2X-Preconfiguration for the frequency, according to 5.10.13.1. The UE shall only use the pool which is associated with the synchronization reference source selected in accordance with 5.10.8.2.

1> if the UE is configured to transmit on p2x-CommTxPoolNormalCommon or on p2x-CommTxPoolNormal in v2x-InterFreqInfoList in SystemInformationBlockType21 or on p2x-CommTxPoolNormal in v2x-InterFreqInfoList in SystemInformationBlockType26 according to 5.10.13.1; or

1> if the UE is configured to transmit on p2x-CommTxPoolList-r14 in SL-V2X-Preconfiguration according to 5.10.13.1; or

1> if zoneConfig is not included in SystemInformationBlockType21 and the UE is configured to transmit on v2x-CommTxPoolNormalCommon or v2x-CommTxPoolNormalDedicated; or

1> if zoneConfig is included in SystemInformationBlockType21 and the UE is configured to transmit on v2x-CommTxPoolNormalDedicated for P2X related V2X sidelink communication and zoneID is not included in v2x-CommTxPoolNormalDedicated; or

1> if zoneConfig is not included in the entry of v2x-InterFreqInfoList for the concerned frequency and the UE is configured to transmit on v2x-CommTxPoolNormal in v2x-InterFreqInfoList or p2x-CommTxPoolNormal in v2x-InterFreqInfoList in RRCConnectionReconfiguration; or

1> if zoneConfig is included in the entry of v2x-InterFreqInfoList for the concerned frequency and the UE is configured to transmit on p2x-CommTxPoolNormal in v2x-InterFreqInfoList in RRCConnectionReconfiguration and zoneID is not included in p2x-CommTxPoolNormal; or

1> if zoneConfig is not included in SL-V2X-Preconfiguration for the concerned frequency and the UE is configured to transmit on v2x-CommTxPoolList in SL-V2X-Preconfiguration for the concerned frequency:

2> select a pool associated with the synchronization reference source selected in accordance with 5.10.8.2;

NOTE 0: If multiple pools are associated with the selected synchronization reference source, it is up to UE implementation which resource pool is selected for V2X sidelink communication transmission.

1> if zoneConfig is included in SystemInformationBlockType21 and the UE is configured to transmit on v2x-CommTxPoolNormalCommon or v2x-CommTxPoolNormalDedicated for non-P2X related V2X sidelink communication; or

1> if zoneConfig is included in SystemInformationBlockType21 and the UE is configured to transmit on v2x-CommTxPoolNormalDedicated for P2X related V2X sidelink communication and zoneID is included in v2x-CommTxPoolNormalDedicated; or

1> if zoneConfig is included in the entry of v2x-InterFreqInfoList for the concerned frequency and if the UE is configured to transmit on v2x-CommTxPoolNormal in v2x-InterFreqInfoList or is configured to transmit on p2x-CommTxPoolNormal in v2x-InterFreqInfoList in RRCConnectionReconfiguration and zoneID is included in p2x-CommTxPoolNormal; or

1> if zoneConfig is included in SL-V2X-Preconfiguration for the concerned frequency and the UE is configured to transmit on v2x-CommTxPoolList in SL-V2X-Preconfiguration for the concerned frequency:

2> select the pool configured with zoneID equal to the zone identity determined below and associated with the synchronization reference source selected in accordance with 5.10.8.2;

The UE shall determine an identity of the zone (i.e. Zone_id) in which it is located using the following formulae, if zoneConfig is included in SystemInformationBlockType21 or SystemInformationBlockType26 or in SL-V2X-Preconfiguration:

x1= FLOOR (x / L) Mod Nx;

y1= FLOOR (y / W) Mod Ny;

Zone_id = y1 * Nx + x1.

The parameters in the formulae are defined as follows:

L is the value of zoneLength included in zoneConfig in SystemInformationBlockType21 or SystemInformationBlockType26 or in SL-V2X-Preconfiguration;

W is the value of zoneWidth included in zoneConfig in SystemInformationBlockType21 or SystemInformationBlockType26 or in SL-V2X-Preconfiguration;

Nx is the value of zoneIdLongiMod included in zoneConfig in SystemInformationBlockType21 or SystemInformationBlockType26 or in SL-V2X-Preconfiguration;

Ny is the value of zoneIdLatiMod included in zoneConfig in SystemInformationBlockType21 or SystemInformationBlockType26 or in SL-V2X-Preconfiguration;

x is the geodesic distance in longitude between UE’s current location and geographical coordinates (0, 0) according to WGS84 model [80] and it is expressed in meters;

y is the geodesic distance in latitude between UE’s current location and geographical coordinates (0, 0) according to WGS84 model [80] and it is expressed in meters.

The UE shall select a pool of resources which includes a zoneID equals to the Zone_id calculated according to above mentioned formulae and indicated by v2x-CommTxPoolNormalDedicated, v2x-CommTxPoolNormalCommon, v2x-CommTxPoolNormal in v2x-InterFreqInfoList or p2x-CommTxPoolNormal in v2x-InterFreqInfoList in RRCConnectionReconfiguration, or v2x-CommTxPoolList according to 5.10.13.1.

NOTE 1: The UE uses its latest geographical coordinates to perform resource pool selection.

NOTE 2: If geographical coordinates are not available and zone specific TX resource pools are configured for the concerned frequency, it is up to UE implementation which resource pool is selected for V2X sidelink communication transmission.

5.10.13.3 V2X sidelink communication transmission reference cell selection

A UE capable of V2X sidelink communication that is configured by upper layers to transmit V2X sidelink communication shall:

1> for each frequency used to transmit V2X sidelink communication, select a cell to be used as reference for synchronisation and DL measurements in accordance with the following:

2> if the frequency concerns the primary frequency:

3> use the PCell (RRC_CONNECTED) or the serving cell (RRC_IDLE) as reference;

2> else if the frequency concerns a secondary frequency:

3> use the concerned SCell as reference;

2> else if the UE is in coverage of the concerned frequency:

3> use the DL frequency paired with the one used to transmit V2X sidelink communication as reference;

2> else (i.e., out of coverage on the concerned frequency):

3> use the PCell (RRC_CONNECTED) or the serving cell (RRC_IDLE) as reference, if needed;

5.10.14 DFN derivation from GNSS

When the UE selects GNSS as the synchronization reference source, the DFN used for V2X sidelink communication is derived from the current UTC time, by the following formulae:

DFN= FLOOR (0.1*(TcurrentTref–offsetDFN)) mod 1024

SubframeNumber= FLOOR (TcurrentTref–offsetDFN) mod 10

Where:

Tcurrent is the current UTC time that obtained from GNSS. This value is expressed in milliseconds;

Tref is the reference UTC time 00:00:00 on Gregorian calendar date 1 January, 1900 (midnight between Thursday, December 31, 1899 and Friday, January 1, 1900). This value is expressed in milliseconds;

OffsetDFN is the value offsetDFN if configured, otherwise it is zero. This value is expressed in milliseconds.

NOTE: In case of leap second change event, how V2X UE obtains the scheduled time of leap second change to adjust Tcurrent correspondingly is left to UE implementation. How V2X UE handles the sudden discontinuity of DFN is left to UE implementation.