Content for TS 38.321 Word version: 18.3.0

1… 4… 5… 5.1.2… 5.2… 5.4… 5.4.4… 5.5… 5.9… 5.18… 5.18.18… 5.19… 5.22… 5.22.1.4… 5.22.2… 5.23… 6… 6.1.3… 6.1.3.8… 6.1.3.11… 6.1.3.17… 6.1.3.21… 6.1.3.26… 6.1.3.31… 6.1.3.37… 6.1.3.42… 6.1.3.49… 6.1.3.53… 6.1.3.59… 6.1.3.64… 6.1.3.70… 6.1.3.74… 6.1.3.79… 6.1.4… 6.2… 7…

5.23 SL-BCH data transfer 5.23.1 SL-BCH data transmission 5.23.2 SL-BCH data reception 5.24 Handling of PRS Processing Window 5.25 Positioning Measurement Gap Activation/Deactivation Request 5.26 Positioning SRS transmission in RRC_INACTIVE 5.26.1 General 5.26.2 TA validation for SRS transmission in RRC_INACTIVE 5.27 Small Data Transmission 5.27.1 General 5.27.2 TA Validation for CG-SDT 5.28 Sidelink Discontinuous Reception (DRX) 5.28.1 General 5.28.2 Behaviour of UE receiving SL-SCH Data 5.28.3 Behaviour of UE transmitting SL-SCH Data 5.29 Activation/Deactivation of SCG 5.30 Handling of FR2 UL gap 5.31 Sidelink LBT operation 5.31.1 General 5.31.2 Sidelink LBT failure detection and recovery procedure 5.32 SRS for positioning Tx frequency hopping 5.33 RACH-less initial UL transmission 5.34 Cell-Level Energy Saving 5.34.1 General 5.34.2 Cell Discontinuous Transmission 5.34.3 Cell Discontinuous Reception
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5.23 SL-BCH data transfer |R16| p. 194

5.23.1 SL-BCH data transmission p. 194

When instructed to send SL-BCH, the MAC entity shall:

1 >

obtain the MAC PDU to transmit from SBCCH;

1 >

deliver the MAC PDU to the physical layer and instruct it to generate a transmission.

5.23.2 SL-BCH data reception p. 194

When the MAC entity needs to receive SL-BCH, the MAC entity shall:

1 >

receive and attempt to decode the SL-BCH;

1 >

if a TB on the SL-BCH has been successfully decoded:

2 >

deliver the decoded MAC PDU to upper layers.

5.24 Handling of PRS Processing Window |R17| p. 195

When PPW is activated and PRS has higher priority than DL channel and signals, for the affected symbols within the PPW according to clause 5.1.6.5 in TS 38.214, the MAC entity shall:

1 >

if the ra-ResponseWindow or the ra-ContentionResolutionTimer or the msgB-ResponseWindow is running:

2 >

monitor the PDCCH as specified in clauses 5.1.4 and 5.1.5.

1 >

else:

2 >

not receive DL-SCH;

2 >

not receive PDCCH.

5.25 Positioning Measurement Gap Activation/Deactivation Request |R17| p. 195

If the UE is configured with pre-configured positioning measurement gap and the request of the activation/deactivation of the positioning measurement gap by UL MAC CE, the UE may request the network to activate or deactivate the Positioning measurement gap with UL MAC CE for Positioning Measurement Gap Activation/Deactivation Request in clause 6.1.3.40.

The MAC entity shall, when triggered by the upper layer to send Positioning Measurement Gap Activation/Deactivation Request, cancel the triggered Positioning Measurement Gap Activation/Deactivation Request, if any and trigger another Positioning Measurement Gap Activation/Deactivation Request according to the upper layer's request.

The MAC entity shall,

1 >

if Positioning Measurement Gap Activation/Deactivation Request MAC CE has been triggered, and not cancelled:

2 >

if indication from upper layer has been received that the triggered Positioning Measurement Gap Activation/Deactivation Request MAC CE should be cancelled; or

2 >

if the pre-configured measurement gap indicated in the Positioning Measurement Gap Activation/Deactivation Request MAC CE has already been activated/deactivated according to clause 5.18.20:

3 >

cancel the triggered Positioning Measurement Gap Activation/Deactivation Request MAC CE.

2 >

if UL-SCH resources are available for a new transmission and these UL-SCH resources can accommodate the Positioning Measurement Gap Activation/Deactivation Request MAC CE plus its subheader as a result of logical channel prioritization:

3 >

instruct the Multiplexing and Assembly procedure to generate the Positioning Measurement Gap Activation/Deactivation Request MAC CE according to the upper layer's request;

3 >

cancel triggered Positioning Measurement Gap Activation/Deactivation Request MAC CE.

2 >

else:

3 >

trigger a Scheduling Request for Positioning Measurement Gap Activation/Deactivation Request MAC CE as specified in clause 5.4.4.

5.26 Positioning SRS transmission in RRC_INACTIVE |R17| p. 195

5.26.1 General p. 195

Periodic and semi-persistent Positioning SRS with or without positioning SRS bandwidth aggregation can be configured for Positioning SRS transmission in RRC_INACTIVE.

SRS for positioning Tx frequency hopping as in clause 5.32 can also be configured for Positioning SRS transmission in RRC_INACTIVE.

The MAC entity shall,

1 >

if the TA of the configured Positioning SRS is valid according to clause 5.26.2, and the conditions for positioning SRS transmission in clause 7.3.1 of TS 38.213 and clause 6.2.1.4 of TS 38.214 are satisfied:

2 >

if the UE is configured with UTW and the UplinkTimeWindowTimer is running according to clause 5.32; or

2 >

if the UE is not configured with UTW:

3 >

instruct to the lower layer according to TS 38.214 to transmit Positioning Periodic SRS or Semi-Persistent SRS that is activated according to clause 5.18.17 or clause 5.18.37.

5.26.2 TA validation for SRS transmission in RRC_INACTIVE p. 196

RRC configures the following parameters for validation for SRS transmission in RRC_INACTIVE:

inactivePosSRS-RSRP-ChangeThreshold: RSRP threshold for the increase/decrease of RSRP for time alignment validation.

The MAC entity shall:

1 >

if the UE receives configuration for SRS transmission in RRC_INACTIVE:

2 >

store the RSRP of the downlink pathloss reference with the current RSRP value of the downlink pathloss reference as in TS 38.331.

1 >

else if the UE is configured with SRS transmission in RRC_INACTIVE:

2 >

if Timing Advance Command MAC CE is received as in clause 5.2, or;

2 >

if Timing Advance Command or Absolute Timing Advance Command is received for Random Access procedure that is successfully completed:

3 >

update the stored the RSRP of the downlink pathloss reference with the current RSRP value of the downlink pathloss reference.

2 >

if the UE is configured with SRS with validity area and the upper layer indicates the MAC to update the stored RSRP:

3 >

update the RSRP of the downlink pathloss reference with the current RSRP value of the downlink pathloss reference of the camped cell as specified in TS 38.331.

The MAC entity shall consider the TA to be valid when the following conditions are fulfilled:

1 >

compared to the stored downlink pathloss reference RSRP value, the current RSRP value of the downlink pathloss reference of the camped cell as specified in TS 38.331 has not increased/decreased by more than inactivePosSRS-RSRP-ChangeThreshold, if configured; and

1 >

inactivePosSRS-TimeAlignmentTimer is running or inactivePosSRS-ValidityAreaTAT is running when positioning validity area is configured.

5.27 Small Data Transmission |R17| p. 196

5.27.1 General p. 196

The MAC entity may be configured by RRC with SDT and the SDT procedure may be initiated by RRC layer for MO-SDT or MT-SDT. The SDT procedure initiated for MO-SDT can be performed either by Random Access procedure with 2-step RA type or 4-step RA type (i.e., RA-SDT) or by configured grant Type 1 (i.e., CG-SDT). The SDT procedure initiated for MT-SDT cannot be performed by RA-SDT (i.e., RA-SDT is not applicable as specified in clause 5.1.1b), but can be performed either by Random Access procedure (i.e., with 2-step RA type or 4-step RA type) or by configured grant Type 1 (i.e., CG-SDT).

RRC configures the following parameters for SDT procedure:

sdt-DataVolumeThreshold: data volume threshold for the UE to determine whether to perform SDT procedure initiated for MO-SDT;
sdt-RSRP-Threshold: RSRP threshold for UE to determine whether to perform SDT procedure initiated for MO-SDT;
mt-SDT-RSRP-Threshold: RSRP threshold for UE to determine whether to perform SDT procedure initiated for MT-SDT;
cg-SDT-RSRP-ThresholdSSB: an RSRP threshold configured for SSB selection for CG-SDT;
cg-MT-SDT-MaxDurationToNextCG-Occasion: time threshold which is used by the UE to determine whether to perform CG-SDT for MT-SDT;
cg-SDT-MaxDurationToNextCG-Occasion: time threshold configured per logical channel which is used by the UE to determine whether to perform CG-SDT for MO-SDT;
sdt-BeamFailureRecoveryProhibitTimer: prohibit timer to avoid frequent triggering of Random Access procedure due to beam failure recovery during RA-SDT procedure or during MT-SDT procedure initiated by Random Access procedure.

The following UE variable is used for the SDT procedure:

MAX_DURATION_TO_NEXT_CG_OCCASION;
RSRP_THRESHOLD.

The MAC entity shall, if initiated by the upper layers for SDT procedure:

1 >

if SDT procedure is initiated for MO-SDT as specified in TS 38.331:

2 >

set the MAX_DURATION_TO_NEXT_CG_OCCASION to the shortest value of cg-SDT-MaxDurationToNextCG-Occasion, if configured, among all the logical channels configured with this parameter by upper layer and having data for transmission;

2 >

set the RSRP_THRESHOLD to the value of sdt-RSRP-Threshold, if configured.

1 >

else if SDT procedure is initiated for MT-SDT as specified in TS 38.331:

2 >

set the MAX_DURATION_TO_NEXT_CG_OCCASION to the value of cg-MT-SDT-MaxDurationToNextCG-Occasion, if configured;

2 >

if mt-SDT-RSRP-Threshold is configured:

3 >

set the RSRP_THRESHOLD to the value of mt-SDT-RSRP-Threshold.

2 >

else if sdt-RSRP-Threshold is configured:

3 >

set the RSRP_THRESHOLD to the value of sdt-RSRP-Threshold.

1 >

if the SDT procedure is initiated for MO-SDT as specified in TS 38.331, and the data volume of the pending UL data across all RBs configured for SDT is less than or equal to sdt-DataVolumeThreshold, or if the SDT procedure is initiated for MT-SDT as specified in TS 38.331; and

1 >

if the RSRP of the downlink pathloss reference is higher than RSRP_THRESHOLD or if RSRP_THRESHOLD is not set:

2 >

if the Serving Cell is configured with supplementary uplink as specified in TS 38.331; and

2 >

if the RSRP of the downlink pathloss reference is less than rsrp-ThresholdSSB-SUL:

3 >

select the SUL carrier.

2 >

else:

3 >

select the NUL carrier.

2 >

if CG-SDT is configured on the selected UL carrier, and TA for CG-SDT is valid according to clause 5.27.2 in the first available CG occasion for initial CG-SDT transmission with CCCH message according to clause 5.8.2; and

2 >

if the SDT procedure is initiated for MO-SDT as specified in TS 38.331, and, for each RB having data available for transmission, configuredGrantType1Allowed, if configured for CG-SDT, is configured with value true for the corresponding logical channel, or if the SDT procedure is initiated for MT-SDT as specified in TS 38.331; and

2 >

if at least one SSB configured for CG-SDT with SS-RSRP above cg-SDT-RSRP-ThresholdSSB is available, and if either the time gap between the initiation of the SDT procedure and first available CG occasion for initial CG-SDT transmission with CCCH message according to clause 5.8.2 is less than MAX_DURATION_TO_NEXT_CG_OCCASION, or if the MAX_DURATION_TO_NEXT_CG_OCCASION is not set:

3 >

indicate to the upper layers that the conditions for initiating SDT procedure are fulfilled;

3 >

perform CG-SDT procedure on the selected UL carrier according to clause 5.8.2.

2 >

else if a set of Random Access resources for RA-SDT is configured and can be selected according to clause 5.1.1b on the selected UL carrier on the BWP configured by initialUplinkBWP-RedCap, if configured for an (e)RedCap UE; otherwise, on the BWP configured by initialUplinkBWP; or

2 >

if the SDT procedure is initiated for MT-SDT as specified in TS 38.331:

3 >

if cg-SDT-TimeAlignmentTimer is running, consider cg-SDT-TimeAlignmentTimer as expired and perform the corresponding actions in clause 5.2;

3 >

indicate to the upper layers that the conditions for initiating SDT procedure are fulfilled.

2 >

else:

3 >

indicate to the upper layers that the conditions for initiating SDT procedure are not fulfilled.

1 >

else:

2 >

indicate to the upper layers that the conditions for initiating SDT procedure are not fulfilled.

If Random Access procedure is selected above for SDT procedure initiated for MO-SDT or MT-SDT and after the Random Access procedure is successfully completed (see clause 5.1.6), the UE monitors PDCCH addressed to C-RNTI received in random access response until the SDT procedure is terminated. If CG-SDT is selected above and after the initial transmission for CG-SDT is performed, the UE monitors PDCCH addressed to C-RNTI as stored in UE Inactive AS context as specified in TS 38.331 and CS-RNTI until the SDT procedure is terminated.

The MAC entity shall:

1 >

if sdt-BeamFailureRecoveryProhibitTimer is configured and not running; and

1 >

if RA-SDT procedure for MO-SDT or MT-SDT procedure initiated by Random Access procedure is ongoing:

2 >

if SS-RSRP of the SSB selected in the last successfully completed Random Access procedure during ongoing RA-SDT procedure or ongoing MT-SDT procedure initiated by Random Access procedure is less than rsrp-ThresholdSSB:

3 >

start the sdt-BeamFailureRecoveryProhibitTimer;

3 >

initiate a Random Access procedure (see clause 5.1).

5.27.2 TA Validation for CG-SDT p. 199

RRC configures the following parameters for TA validation for CG-SDT:

cg-SDT-RSRP-ChangeThreshold: RSRP threshold for the increase/decrease of RSRP for time alignment validation.

The MAC entity shall, upon the reception of CG-SDT configuration:

1 >

store the current RSRP of the downlink pathloss reference for TA validation as defined in clause 5.7.17 of TS 38.331.

The MAC entity shall consider the TA of the initial CG-SDT transmission with CCCH message to be valid when the following conditions are fulfilled:

1 >

The RSRP values for the stored downlink pathloss reference and the current downlink pathloss reference are valid according to TS 38.133; and

1 >

Compared to the stored downlink pathloss reference RSRP value, the current RSRP value of the downlink pathloss reference calculated as specified in TS 38.133 has not increased/decreased by more than cg-SDT-RSRP-ChangeThreshold, if configured; and

1 >

cg-SDT-TimeAlignmentTimer is running.

5.28 Sidelink Discontinuous Reception (DRX) |R17| p. 199

5.28.1 General p. 199

The MAC entity may be configured by RRC with an SL DRX functionality that controls the UE's SCI (i.e., 1st stage SCI and 2nd stage SCI) monitoring activity for unicast, groupcast and broadcast. When using SL DRX operation, the MAC entity shall also monitor SCI (i.e., 1st stage SCI and 2nd stage SCI) according to requirements found in other clauses of this specification.

Sidelink DRX and UE procedure on SL-PRS Dedicated resource pool are not applied at the same time.

RRC controls Sidelink DRX operation by configuring the following parameters:

sl-drx-onDurationTimer/sl-DRX-GC-BC-OnDurationTimer: the duration at the beginning of an SL DRX cycle;
sl-drx-SlotOffset: the delay before starting the sl-drx-onDurationTimer/sl-DRX-GC-BC-OnDurationTimer;
sl-drx-InactivityTimer/sl-DRX-GC-InactivityTimer (except for the SL broadcast communication): the duration after the first slot of SCI (i.e., 1st stage SCI and 2nd stage SCI) reception in which an SCI indicates a new SL transmission for the MAC entity;
sl-drx-RetransmissionTimer/sl-DRX-GC-RetransmissionTimer (per Sidelink process except for the SL broadcast process): the maximum duration until an SL retransmission is received;
sl-drx-StartOffset: the slot where the SL DRX cycle starts;
sl-drx-Cycle/sl-DRX-GC-BC-Cycle: the Sidelink DRX cycle;
sl-drx-HARQ-RTT-Timer/sl-DRX-GC-HARQ-RTT-Timer (per Sidelink process except for the SL broadcast process): the minimum duration before an SL HARQ retransmission is expected by the MAC entity.

5.28.2 Behaviour of UE receiving SL-SCH Data p. 200

When SL DRX is configured, the Active Time includes the time while:

sl-drx-onDurationTimer/sl-DRX-GC-BC-OnDurationTimer or sl-drx-InactivityTimer/sl-DRX-GC-InactivityTimer is running; or
sl-drx-RetransmissionTimer/sl-DRX-GC-RetransmissionTimer is running; or
period of sl-LatencyBoundCSI-Report configured by RRC in case SL-CSI reporting MAC CE is not received; or
the time between the transmission of the request of SL-CSI reporting and the reception of the SL-CSI reporting MAC CE in case SL-CSI reporting MAC CE is received; or
Slot(s) associated with the announced periodic transmission(s) by the UE transmitting SL-SCH Data; or
the time between transmission/reception of Direct Link Establishment Request message (TS 24.587) or ProSe Direct Link Establishment Request message (TS 24.554) and reception of RRCReconfigurationSidelink message including initial DRX configuration or the link establishment procedure being aborted by upper layer; or
the time between transmission of RRCReconfigurationSidelink message including initial DRX configuration and reception of corresponding RRCReconfigurationCompleteSidelink or RRCReconfigurationFailureSidelink message.

When one or multiple SL DRX is configured, the MAC entity shall:

1 >

if a single sl-DRX-GC-BC-Cycle that is mapped with one or multiple SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List or a single sl-DRX-GC-BC-Cycle that is configured in sl-DefaultDRX-GC-BC and cannot be mapped with any SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List is associated to a Destination and the associated cast type is groupcast or broadcast:

2 >

select the sl-DRX-GC-BC-Cycle that is mapped with one or multiple SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List or the sl-DRX-GC-BC-Cycle configured in sl-DefaultDRX-GC-BC associated with the Destination.

1 >

else if multiple sl-DRX-GC-BC-Cycle that include one or multiple sl-DRX-GC-BC-Cycle that are mapped with one or multiple SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List and, if applicable, one sl-DRX-GC-BC-Cycle that is configured in sl-DefaultDRX-GC-BC and cannot be mapped with any SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List are associated to a Destination Layer-2 ID and the associated cast type groupcast or broadcast:

2 >

select the sl-DRX-GC-BC-Cycle whose length is the shortest one among multiple sl-DRX-GC-BC-Cycle that are mapped with one or multiple SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List and sl-DRX-GC-BC-Cycle configured in sl-DefaultDRX-GC-BC associated with the Destination Layer-2 ID.

1 >

if a single sl-DRX-GC-BC-OnDurationTimer that is mapped with one or multiple SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List or a single sl-DRX-GC-BC-OnDurationTimer that is configured in sl-DefaultDRX-GC-BC and cannot be mapped with any SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List is associated to a Destination and the associated cast type is groupcast or broadcast:

2 >

select the sl-DRX-GC-BC-OnDurationTimer that is mapped with one or multiple SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List or the sl-DRX-GC-BC-OnDurationTimer configured in sl-DefaultDRX-GC-BC associated with the Destination.

1 >

else if multiple sl-DRX-GC-BC-OnDurationTimer that include one or multiple sl-DRX-GC-BC-OnDurationTimer that are mapped with one or multiple SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List and, if applicable, one sl-DRX-GC-BC-OnDurationTimer that is configured in sl-DefaultDRX-GC-BC and cannot be mapped with any SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List are associated to a Destination Layer-2 ID and the associated cast type is groupcast or broadcast:

2 >

select the sl-DRX-GC-BC-OnDurationTimer whose length is the longest one among multiple sl-DRX-GC-BC-OnDurationTimer that are mapped with one or multiple SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List and sl-DRX-GC-BC-Cycle configured in sl-DefaultDRX-GC-BC associated with the Destination Layer-2 ID.

1 >

if a single sl-DRX-GC-InactivityTimer that is mapped with one or multiple SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List or a single sl-DRX-GC-InactivityTimer that is configured in sl-DefaultDRX-GC-BC and cannot be mapped with any SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List is associated to a Destination and the associated cast type is groupcast:

2 >

select the sl-DRX-GC-InactivityTimer that is mapped with one or multiple SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List or the sl-DRX-GC-InactivityTimer configured in sl-DefaultDRX-GC-BC associated with the Destination:

1 >

else if multiple sl-DRX-GC-InactivityTimer that include one or multiple sl-DRX-GC-InactivityTimer that are mapped with one or multiple SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List and, if applicable, one sl-DRX-GC-InactivityTimer that is configured in sl-DefaultDRX-GC-BC and cannot be mapped with any SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List of a Destination Layer-2 ID and the associated cast type is groupcast:

2 >

select sl-DRX-GC-InactivityTimer whose length is the longest one among multiple sl-DRX-GC-InactivityTimer that are mapped with one or multiple SL-QoS-Profile in sl-DRX-GC-BC-PerQoS-List and sl-DRX-GC-InactivityTimer configured in sl-DefaultDRX-GC-BC associated with the Destination Layer-2 ID.

1 >

if an sl-drx-HARQ-RTT-Timer expires:

2 >

if the data of the corresponding Sidelink process was not successfully decoded or if the HARQ feedback (i.e., negative acknowledgement) is not transmitted for unicast due to UL/SL prioritization:

3 >

start the sl-drx-RetransmissionTimer/sl-DRX-GC-RetransmissionTimer for the corresponding Sidelink process in the first slot after the expiry of sl-drx-HARQ-RTT-Timer.

When the cast type is groupcast or broadcast as indicated by upper layer, or the cast type is unicast for the reception of Direct Link Establishment Request message [28] or ProSe Direct Link Establishment Request message [29] as indicated by upper layer, or for the reception of discovery message [26], the sl-drx-StartOffset and sl-drx-SlotOffset are derived from the following equations:

sl-drx-StartOffset (ms) = Destination Layer-2 ID modulo sl-DRX-GC-BC-Cycle (ms).

sl-drx-SlotOffset (ms) = (Destination Layer-2 ID modulo the number of slots in one subframe)

/ (the number of slots in one subframe) (ms).

1 >

if the SL DRX cycle is used, and [(DFN × 10) + subframe number] modulo (sl-drx-Cycle or sl-DRX-GC-BC-Cycle) = sl-drx-StartOffset:

2 >

start sl-drx-onDurationTimer/sl-DRX-GC-BC-OnDurationTimer after sl-drx-SlotOffset from the beginning of the subframe.

1 >

if an SL DRX is in Active Time:

2 >

monitor the SCI (i.e., 1st stage SCI and 2nd stage SCI).

2 >

if the SCI indicates a new SL transmission:

3 >

if Source Layer-1 ID of the SCI is equal to the 8 LSB of the intended Destination Layer-2 ID and Destination Layer-1 ID of the SCI is equal to the 16 LSB of the intended Source Layer-2 ID and the cast type indicator in the SCI is set to unicast:

4 >

start or restart sl-drx-InactivityTimer for the corresponding Source Layer-2 ID and Destination Layer-2 ID pair in the first slot after SCI reception.

3 >

if Destination Layer-1 ID of the SCI (i.e., 2nd stage SCI) is equal to the 16 LSB of the intended Destination Layer-2 ID and the cast type indicator in the SCI is set to groupcast:

4 >

start or restart sl-DRX-GC-InactivityTimer for the corresponding Destination Layer-2 ID in the first slot after SCI reception.

2 >

if the SCI indicates an SL transmission:

3 >

if a next retransmission opportunity is indicated in the SCI:

4 >

derive the sl-drx-HARQ-RTT-Timer from the retransmission resource timing of the next retransmission resource in the SCI.

3 >

else if PSFCH resource is configured for the SL grant associated to the SCI:

4 >

set the sl-drx-HARQ-RTT-Timer based on sl-drx-HARQ-RTT-Timer1 configured by upper layer if the cast type associated with the SCI is unicast or sl-DRX-GC-HARQ-RTT-Timer1 configured by upper layer if the cast type associated with the SCI is groupcast when HARQ feedback is enabled, or based on sl-drx-HARQ-RTT-Timer2 configured by upper layer if the cast type associated with the SCI is unicast or sl-DRX-GC-HARQ-RTT-Timer2 configured by upper layer if the cast type associated with the SCI is groupcast when HARQ feedback is disabled, for resource pool configured with PSFCH.

3 >

else (i.e., if PSFCH resource is not configured for the SL grant associated to the SCI):

4 >

set the sl-drx-HARQ-RTT-Timer as 0 slots.

3 >

if PSFCH resource is not configured for the SL grant associated to the SCI:

4 >

start the sl-drx-HARQ-RTT-Timer for the corresponding Sidelink process in the slot following the end of PSSCH transmission (i.e., currently received PSSCH).

3 >

if PSFCH resource is configured for the SL grant associated to the SCI:

4 >

if HARQ feedback is enabled by the SCI and the cast type associated with the SCI is unicast:

5 >

if sl-NumPSFCH-Occasions is configured as specified in TS 38.331:

6 >

start the sl-drx-HARQ-RTT-Timer for the corresponding Sidelink process in the first slot after the end of corresponding PSFCH transmission carrying the SL HARQ Feedback when the SL HARQ feedback is successfully transmitted in one of PSFCH occasions from sl-NumPSFCH-Occasions; or

6 >

start the sl-drx-HARQ-RTT-Timer for the corresponding Sidelink process in the first slot after the end of the last PSFCH occasion for the SL HARQ Feedback when the SL HARQ feedback is not transmitted in all PSFCH occasions from sl-NumPSFCH-Occasions.

5 >

else:

6 >

start the sl-drx-HARQ-RTT-Timer for the corresponding Sidelink process in the first slot after the end of the corresponding PSFCH transmission carrying the SL HARQ feedback; or

6 >

start the sl-drx-HARQ-RTT-Timer for the corresponding Sidelink process in the first slot after the end of the corresponding PSFCH resource for the SL HARQ feedback when the SL HARQ feedback is not transmitted due to UL/SL prioritization or SL LBT failure.

4 >

if HARQ feedback is enabled by the SCI and the cast type associated with the SCI is groupcast and positive-negative acknowledgement is selected:

5 >

if sl-NumPSFCH-Occasions is configured as specified in TS 38.331:

6 >

start the sl-drx-HARQ-RTT-Timer for the corresponding Sidelink process in the first slot after the end of the last PSFCH occasion for the SL HARQ Feedback.

5 >

else:

6 >

start the sl-drx-HARQ-RTT-Timer for the corresponding Sidelink process in the first slot after the end of the corresponding PSFCH transmission carrying the SL HARQ feedback; or

6 >

4 >

if HARQ feedback is enabled by the SCI and the cast type associated with the SCI is groupcast and negative-only acknowledgement is selected;

5 >

start the sl-drx-HARQ-RTT-Timer for the corresponding Sidelink process in the first slot after the end of the corresponding PSFCH transmission carrying the SL HARQ feedback; or

5 >

4 >

if HARQ feedback is disabled by the SCI and the resource(s) for one or more retransmission opportunities is not scheduled in the SCI:

5 >

if sl-NumPSFCH-Occasions is configured as specified in TS 38.331:

6 >

start the sl-drx-HARQ-RTT-Timer for the corresponding Sidelink process in the first slot after the end of the last PSFCH occasion.

5 >

else:

6 >

start the sl-drx-HARQ-RTT-Timer for the corresponding Sidelink process in the slot following the end of PSFCH resource.

4 >

if HARQ feedback is disabled by the SCI and the resource(s) for one or more retransmission opportunities is scheduled in the SCI:

5 >

start the sl-drx-HARQ-RTT-Timer for the corresponding Sidelink process in the slot following the end of PSSCH transmission (i.e., currently received PSSCH).

3 >

stop the sl-drx-RetransmissionTimer/sl-DRX-GC-RetransmissionTimer for the corresponding Sidelink process.

1 >

if an SL DRX Command MAC CE is received for the Source Layer-2 ID and Destination Layer-2 ID pair of a unicast:

2 >

stop sl-drx-onDurationTimer for the Source Layer-2 ID and Destination Layer-2 ID pair of a unicast;

2 >

stop sl-drx-InactivityTimer for the Source Layer-2 ID and Destination Layer-2 ID pair of a unicast.

5.28.3 Behaviour of UE transmitting SL-SCH Data p. 203

The UE transmitting SL-SCH Data should keep aligned with its intended UE receiving the SL-SCH Data regarding the SL DRX Active time as specified in clause 5.28.2.

Furthermore, the UE transmitting SL-SCH Data determines the SL DRX Active time based on SL DRX timers that are running (e.g., sl-drx-onDurationTimer/sl-DRX-GC-BC-OnDurationTimer, sl-drx-InactivityTimer/sl-DRX-GC-InactivityTimer, sl-drx-RetransmissionTimer/sl-DRX-GC-RetransmissionTimer) or will be running in the future (e.g., sl-drx-onDurationTimer/sl-DRX-GC-BC-OnDurationTimer, sl-drx-InactivityTimer/sl-DRX-GC-InactivityTimer, sl-drx-RetransmissionTimer/sl-DRX-GC-RetransmissionTimer) at the UE(s) receiving SL-SCH data. The UE may select resource for the initial transmission of groupcast within the time when sl-DRX-GC-BC-OnDurationTimer or sl-DRX-GC-InactivityTimer of the destination is running.

The MAC entity shall for each Destination Layer-2 ID associated with groupcast that is interested in NR sidelink transmision:

1 >

if the SCI indicates a new transmission where the cast type is set to groupcast is transmitted:

2 >

start or restart sl-DRX-GC-InactivityTimer for the corresponding Destination Layer-2 ID in the first slot after SCI transmission.

The MAC entity shall for each pair of the Source Layer-2 ID and the Destination Layer-2 ID corresponding to each PC5-RRC connection which has been established by upper layers:

1 >

if the SL DRX Command indication has been triggered by the UE:

2 >

if the MAC entity has SL resources allocated for new transmission and the SL-SCH resources can accommodate the SL DRX Command MAC CE and its subheader as a result of logical channel prioritization:

3 >

instruct the Multiplexing and Assembly procedure to generate a Sidelink DRX Command MAC CE as defined in clause 6.1.3.52;

3 >

cancel the triggered SL DRX Command indication.

2 >

else if the MAC entity has been configured with Sidelink resource allocation mode 1:

3 >

trigger a Scheduling Request.

5.29 Activation/Deactivation of SCG |R17| p. 204

The network may activate and deactivate the configured SCG.

The MAC entity shall for the configured SCG:

1 >

if upper layers indicate that SCG is activated:

2 >

if BFI_COUNTER ≥ beamFailureInstanceMaxCount for the PSCell or the timeAlignmentTimer associated with PTAG is not running:

3 >

indicate to upper layers that a Random Access Procedure (as specified in clause 5.1.1) is needed for SCG activation.

2 >

activate the SCG according to the timing defined in TS 38.133.

2 >

(re-)initialize any suspended configured uplink grants of configured grant Type 1 associated with this PSCell according to the stored configuration, if any, and to start in the symbol according to rules in clause 5.8.2.2;

2 >

apply normal SCG operation including:

3 >

SRS transmissions on the PSCell;

3 >

CSI reporting for the PSCell;

3 >

PDCCH monitoring on the PSCell;

3 >

PUCCH transmissions on the PSCell;

3 >

transmit on RACH on the PSCell;

3 >

initialize Bj for each logical channel to zero.

1 >

else if upper layers indicate that the SCG is deactivated:

2 >

deactivate all the SCells of the SCG according to clause 5.9;

2 >

deactivate SCG according to the timing defined in TS 38.133;

2 >

clear any configured downlink assignment and any configured uplink grant Type 2 associated with the PSCell respectively;

2 >

suspend any configured uplink grant Type 1 associated with the PSCell;

2 >

reset MAC according to clause 5.12;

2 >

flush all HARQ buffers associated with the PSCell.

1 >

if the SCG is deactivated:

2 >

not transmit SRS on the PSCell;

2 >

not report CSI for the PSCell;

2 >

not transmit on UL-SCH on the PSCell;

2 >

not transmit PUCCH on the PSCell;

2 >

not transmit on RACH on the PSCell;

2 >

not monitor the PDCCH on the PSCell.

5.30 Handling of FR2 UL gap |R17| p. 205

During the FR2 UL gap configured by ul-GapFR2-Config as specified in TS 38.331, the MAC entity shall, on the Serving Cell(s) of FR2 single CC and intra-band CA, or on the Serving Cell(s) of FR2 inter-band CA where UE does not support tx-Support-UL-GapFR2:

1 >

only perform transmission of:

2 >

PRACH preamble as specified in clause 5.1.2 and 5.1.2a;

2 >

UL-SCH for Msg3 or the MSGA payload as specified in clause 5.4.2.2;

2 >

UL-SCH for configured grant;

2 >

the valid CSI report during SCell activation procedure where the valid CSI report is valid CQI with non-zero CQI index defined in clause 5.2.2.1 of TS 38.214, when the time period between UL gap colliding with CSI report of non-zero CQI and the slot where the SCell activation MAC CE or CSI report activation command is received is no less than 10 ms;

2 >

the valid L1 RSRP report during SCell activation procedure, where the valid L1 RSRP report is non lowest L1 RSRP defined in clause 10.1.6 of TS 38.133, when the time period between UL gap colliding with L1 RSRP reporting and the slot where the SCell activation MAC CE or CSI report activation command is received is no less than 10 ms;

2 >

the PUCCH transmission for SR, and link recovery request (LRR) defined in clause 8.5 of TS 38.133.

5.31 Sidelink LBT operation |R18| p. 205

5.31.1 General p. 205

The lower layer may perform an SL LBT procedure, see TS 37.213, according to which a transmission is not performed by lower layers if the channel is identified as being occupied. When lower layer performs an SL LBT procedure before a transmission and the transmission is not performed, an SL LBT failure indication is sent to the MAC entity from lower layers. Unless otherwise specified, when SL LBT procedure is performed for a transmission, actions as specified in this specification are performed regardless of if an SL LBT failure indication is received from lower layers. When SL LBT is not performed by the lower layers, SL LBT failure indication is not received from lower layers.

5.31.2 Sidelink LBT failure detection and recovery procedure p. 205

The MAC entity may be configured by RRC with a Sidelink consistent LBT failure detection and recovery procedure. Sidelink consistent LBT failure is detected per RB set by counting SL LBT failure indications, for all SL transmissions, from the lower layers to the MAC entity.

RRC configures the following parameters in the sl-lbt-FailureRecoveryConfig:

sl-lbt-FailureInstanceMaxCount for the Sidelink consistent LBT failure detection;
sl-lbt-FailureDetectionTimer for the Sidelink consistent LBT failure detection;
sl-LBT-RecoveryTimer for recovery of the triggered Sidelink consistent LBT failure.

The following UE variable is used for the Sidelink consistent LBT failure detection procedure:

SL_LBT_COUNTER (per RB set): counter for SL LBT failure indication which is initially set to 0.

For activated SL BWP configured with sl-lbt-FailureRecoveryConfig, the MAC entity shall:

1 >

if SL LBT failure indication has been received from lower layers for an RB set of the configured pool(s) of resources in the SL BWP:

2 >

start or restart the sl-lbt-FailureDetectionTimer for the RB set;

2 >

increment SL_LBT_COUNTER for the RB set by 1;

2 >

if SL_LBT_COUNTER ≥ sl-lbt-FailureInstanceMaxCount:

3 >

trigger Sidelink consistent LBT failure for the RB set in the SL BWP;

3 >

if consistent LBT failure has been triggered in all the RB sets of the configured pool(s) of resources in the SL BWP:

4 >

indicate Sidelink consistent LBT failure based Sidelink RLF detection for all destination IDs associated to unicast service to upper layers.

1 >

if all triggered Sidelink consistent LBT failures are cancelled in a RB set; or

1 >

if the sl-lbt-FailureDetectionTimer expires for a RB set:

2 >

set SL_LBT_COUNTER to 0 for the RB set.

1 >

if sl-lbt-FailureDetectionTimer or sl-lbt-FailureInstanceMaxCount is reconfigured by upper layers:

2 >

set SL_LBT_COUNTER to 0 for all the RB sets.

The sl-LBT-RecoveryTimer is used for recovery of the triggered Sidelink consistent LBT failure, when RRC configures Sidelink resource allocation mode 2.

The MAC entity shall:

1 >

if Sidelink consistent LBT failure has been triggered, and not cancelled, in the RB set(s), and SL LBT failure MAC CE for the triggered Sidelink consistent LBT failure has not been generated;

2 >

if the sl-LBT-RecoveryTimer for the triggered Sidelink consistent LBT failure is not running:

3 >

start the sl-LBT-RecoveryTimer.

2 >

if UL-SCH resources are available for a new transmission and the UL-SCH resources can accommodate the SL LBT failure MAC CE plus its subheader as a result of logical channel prioritization according to clause 5.4.3.1:

3 >

instruct the Multiplexing and Assembly procedure in clause 5.4.3 to generate the SL LBT failure MAC CE(s).

2 >

else:

3 >

trigger a Scheduling Request for SL LBT failure MAC CE.

1 >

if a MAC PDU is transmitted and this PDU includes the SL LBT failure MAC CE; or

2 >

cancel the triggered Sidelink consistent LBT failure(s) in RB set(s) for which Sidelink consistent LBT failure was indicated in the transmitted SL LBT failure MAC CE if the MAC entity has been configured with Sidelink resource allocation mode 1.

1 >

if the sl-LBT-RecoveryTimer for the triggered Sidelink consistent LBT failure(s) expires:

2 >

cancel the triggered Sidelink consistent LBT failure(s) in RB set(s) for which Sidelink consistent LBT failure was detected.

1 >

if sl-lbt-FailureRecoveryConfig is reconfigured by upper layers for the BWP:

2 >

cancel all the triggered Sidelink consistent LBT failure(s) in the SL BWP.

5.32 SRS for positioning Tx frequency hopping |R18| p. 207

SRS for positioning Tx frequency hopping can be supported for UE in RRC_CONNECTED and RRC_INACTIVE. The UE can be configured with UTW during which the UE is allowed to transmit SRS for positioning Tx frequency hopping.

RRC configures the following parameters for the UTW for SRS for positioning Tx frequency hopping:

utw-SlotPeriodicity: Periodicity of the UTW in slot;
utw-SlotOffset: Offset of the beginning of the UTW with respect to the beginning of the UTW periodicity in time domain in slot;
uplinkTimeWindowTimer: Time duration when the UE performs SRS transmission for positioning Tx frequency hopping.

When UTW is configured, the MAC entity shall start the uplinkTimeWindowTimer in the first symbol of the slot for which the following condition is satisfied

CURRENT_slot modulo (utw-SlotPeriodicity) = utw-SlotOffset

where CURRENT_slot = (SFN × numberOfSlotsPerFrame) + slot number in the frame and numberOfSlotsPerFrame refers to the number of consecutive slots per frame as specified in TS 38.211.

When UTW is configured and the UE is in RRC_CONNECTED, the MAC entity shall instruct the lower layer to transmit SRS for positioning Tx frequency hopping when the uplinkTimeWindowTimer is running.

5.33 RACH-less initial UL transmission |R18| p. 207

The initial uplink transmission of a RACH-less handover procedure can be performed either using a dynamic uplink grant or a configured uplink grant Type 1 preallocated by RRC, if configured.

When rach-LessHO is configured, the MAC entity shall:

1 >

if cg-RRC-Configuration is configured:

2 >

select a configured uplink grant for initial uplink transmission according to clause 5.8.2;

2 >

perform initial uplink transmission in the first available CG occasion for RACH-less handover according to clause 5.8.2;

2 >

monitor the PDCCH as specified in clause 5.7 and TS 38.213.

1 >

else:

2 >

if tci-StateID is configured in rach-LessHO:

3 >

indicate to lower layers the TCI state information included in tci-StateID.

2 >

else if ssb-Index is configured in rach-LessHO:

3 >

indicate to lower layers the SSB index included in ssb-Index.

2 >

monitor the PDCCH as specified in TS 38.213.

5.34 Cell-Level Energy Saving |R18| p. 208

5.34.1 General p. 208

Each Serving Cell may be configured by RRC with a periodic cell DTX pattern (i.e., Active and Non-Active Periods). The cell DTX operation controls UE's monitoring activity of PDCCH and configured downlink assignments in RRC_CONNECTED. For all activated Serving Cells with cell DTX configured and activated, the MAC entity may monitor PDCCH and configured downlink assignments using the cell DTX operation specified in clause 5.34.2.

Each Serving Cell may be configured by RRC with a periodic cell DRX pattern (i.e., Active and Non-Active Periods). The cell DRX operation controls Scheduling Request and configured uplink grant transmission activity in RRC_CONNECTED. For all activated Serving Cells with cell DRX configured and activated, the MAC entity may transmit configured uplink grant transmissions and Scheduling Request using the cell DRX operation specified in clause 5.34.3.

RRC controls cell DTX and cell DRX operation by configuring the following parameters in cellDTX-DRX-Config per Serving Cell:

cellDTX-DRX-ConfigType: defines whether only cell DTX is configured, only cell DRX is configured, or both are configured;
cellDTX-DRX-onDurationTimer: the active duration at the beginning of a cell DTX/DRX cycle;
cellDTX-DRX-StartOffset: defines the subframe where the cell DTX/DRX cycle starts;
cellDTX-DRX-SlotOffset: the delay before starting the cellDTX-DRX-onDurationTimer;
cellDTX-DRX-Cycle: the cell DTX/DRX cycle period.
cellDTX-DRX-ActivationStatus: the initial activation status of cell DTX and cell DRX operation.

5.34.2 Cell Discontinuous Transmission p. 208

Cell DTX is configured if cellDTX-DRX-ConfigType is set to dtx or dtxdrx. Cell DTX operation is activated and deactivated for each Serving Cell by:

receiving a cell DTX indication from lower layers indicating activation or deactivation of cell DTX operation, as specified in TS 38.213;
configuring cellDTX-DRX-Config by upper layers: if cell DTX is configured and cellDTX-DRX-ActivationStatus is set to activated, cell DTX operation is activated upon cell DTX configuration; if cell DTX is configured and cellDTX-DRX-ActivationStatus is set to deactivated, cell DTX operation is deactivated upon cell DTX configuration; if cellDTX-DRX-Config is released, cell DTX operation is deactivated and all the corresponding configurations are released.

When cell DTX is configured and activated for a Serving Cell, the cell DTX Active Period includes the time while:

cellDTX-DRX-onDurationTimer is running for the associated Serving Cell.

For each Serving Cell configured with cell DTX, the MAC entity shall:

1 >

if cell DTX is activated for this Serving Cell:

2 >

if [(SFN × 10) + subframe number] modulo (cellDTX-DRX-Cycle) = (cellDTX-DRX-StartOffset):

3 >

start cellDTX-DRX-onDurationTimer for this serving cell after cellDTX-DRX-SlotOffset from the beginning of the subframe.

1 >

if cell DTX operation is deactivated for this Serving Cell; or

1 >

if the Serving Cell is in the cell DTX Active Period:

2 >

monitor PDCCH on this Serving Cell, as specified in TS 38.213 and other clauses of this specification.

1 >

if any drx-RetransmissionTimerDL, drx-RetransmissionTimerUL or drx-RetransmissionTimerSL (as described in clause 5.7) is running on any Serving Cell in the DRX group of this Serving Cell; or

1 >

if ra-ContentionResolutionTimer (as described in clause 5.1.5) or msgB-ResponseWindow (as described in clause 5.1.4a) is running; or

1 >

if a Scheduling Request is sent on PUCCH and is pending (as described in clause 5.4.4 or 5.22.1.5); or

1 >

if a PDCCH indicating a new transmission addressed to the C-RNTI of the MAC entity has not been received after successful reception of a Random Access Response for the Random Access Preamble not selected by the MAC entity among the contention-based Random Access Preamble (as described in clauses 5.1.4 and 5.1.4a):

2 >

monitor PDCCH on the Serving Cells in the DRX group of this Serving Cell, as specified in TS 38.213 and other clauses of this specification.

1 >

if ra-ResponseWindow (as described in clause 5.1.4) is running and this Serving Cell is the SpCell:

2 >

monitor PDCCH on this Serving Cell (as described in clause 5.1.4).

For each Serving Cell configured with cell DTX, the MAC entity need not:

1 >

if cell DTX operation is activated and the Serving Cell is not in the cell DTX Active Period:

2 >

monitor PDCCH for the MAC entity's RNTIs listed in clauses 5.7 and 5.7b, irrespective of the requirements of clauses 5.7 and 5.7b, unless stated otherwise in this clause;

2 >

instruct the physical layer to receive transport block on the DL-SCH of this Serving Cell according to a configured downlink assignment for SPS;

2 >

indicate the presence of a configured downlink assignment and deliver the stored HARQ information to the HARQ entity;

2 >

set the HARQ Process ID to the HARQ Process ID associated with the PDSCH duration of a configured downlink assignment;

2 >

consider the NDI bit for the HARQ process corresponding to the PDSCH duration of a configured downlink assignment to have been toggled for the configured downlink assignment.

5.34.3 Cell Discontinuous Reception p. 209

Cell DRX is configured if cellDTX-DRX-ConfigType is set to drx or dtxdrx. Cell DRX operation is activated and deactivated for each Serving Cell by:

receiving a cell DRX indication from lower layers indicating activation or deactivation of cell DRX operation, as specified in TS 38.213;
configuring cellDTX-DRX-Config by upper layers: if cell DRX is configured and cellDTX-DRX-ActivationStatus is set to activated, cell DRX operation is activated upon cell DRX configuration; if cell DRX is configured and cellDTX-DRX-ActivationStatus is set to deactivated, cell DRX operation is deactivated upon cell DRX configuration; if cellDTX-DRX-Config is released, cell DRX operation is deactivated and all the corresponding configurations are released.

When cell DRX is configured and activated for a Serving Cell, the cell DRX Active Period includes the time while:

cellDTX-DRX-onDurationTimer is running for the associated Serving Cell.

For each Serving Cell configured with cell DRX, the MAC entity shall:

1 >

if cell DRX is activated for this Serving Cell:

2 >

if [(SFN × 10) + subframe number] modulo (cellDTX-DRX-Cycle) = (cellDTX-DRX-StartOffset):

3 >

start cellDTX-DRX-onDurationTimer for this serving cell after cellDTX-DRX-SlotOffset from the beginning of the subframe.

1 >

if cell DRX is activated and the Serving Cell is not in the cell DRX Active Period:

2 >

not instruct the physical layer to signal a SR on a PUCCH resource for SR;

2 >

not increment the SR_COUNTER for a SR;

2 >

not start the sr-ProhibitTimer for a SR;

2 >

not deliver any configured uplink grant and the associated HARQ information to the HARQ entity;

2 >

not instruct a HARQ process associated with a configured uplink grant to trigger a new transmission or a retransmission;

2 >

not report CSI on PUCCH and semi-persistent CSI configured on PUSCH;

2 >

if an emergency service is initiated by upper layers and this Serving Cell is the SpCell:

3 >

initiate a Random Access procedure (as specified in clause 5.1.1).