HK40100591A - Method and apparatus for discontinuous reception regarding physical uplink control channel - Google Patents

Description

Methods and apparatus for discontinuous reception of the physical uplink control channel

Cross-reference of related applications

This application claims priority and benefit to U.S. Provisional Patent Application No. 63/333,944, filed April 22, 2022, which is incorporated herein by reference in its entirety.

Technical Field

This disclosure generally relates to wireless communication networks, and more specifically, to methods and apparatus for discontinuous reception of PUCCH transmissions in wireless communication systems.

Background Technology

With the rapid growth in demand for transmitting large amounts of data to and from mobile communication devices, traditional mobile voice communication networks have evolved into networks that communicate with Internet Protocol (IP) packets. This type of IP packet communication can provide users of mobile communication devices with IP-bearing voice, multimedia, multicast, and video-on-demand communication services.

An exemplary network architecture is the Evolved Universal Terrestrial Radio Access Network (E-UTRAN). E-UTRAN systems can provide high data throughput to enable the aforementioned IP-based voice and multimedia services. Currently, the 3rd Generation Partnership Project (3GPP) standards organization is discussing new next-generation (e.g., 5G) radio technologies. Therefore, changes to the current body of the 3GPP standards are being submitted and considered to evolve and finalize the 3GPP standards.

Summary of the Invention

This invention provides methods, systems, and apparatus for processing Physical Downlink Control Channel (PDCCH) monitoring associated with sidelink (SL) communications related to measurement intervals and Listen-Before-Talk (LBT) failures. In various embodiments of the invention, a method for a first apparatus in a wireless communication system includes: receiving an SL grant, wherein the SL grant indicates an SL transmission; when the first apparatus fails to transmit an SL HARQ feedback for an SL Hybrid Automatic Repeat Request (HARQ) process on a Physical Uplink Control Channel (PUCCH) resource due to a measurement interval or LBT failure, starting or restarting a first timer for the SL HARQ process in a first symbol after the end of the PUCCH resource associated with the SL grant or SL transmission; when the first apparatus fails to transmit an SL HARQ feedback for the SL HARQ process on a PUCCH resource due to a measurement interval or LBT failure and the SL HARQ feedback is a negative acknowledgment (NACK), starting or restarting a second timer for the SL HARQ process in a first symbol after the expiration of the first timer; and monitoring the PDCCH while the second timer is running.

Attached Figure Description

Figure 1 shows a diagram of a wireless communication system according to an embodiment of the present invention;

Figure 2 is a block diagram of a transmitter system (also referred to as an access network) and a receiver system (also referred to as a user equipment or UE) according to an embodiment of the present invention;

Figure 3 is a functional block diagram of a communication system according to an embodiment of the present invention;

Figure 4 is a functional block diagram of the program code of Figure 3 according to an embodiment of the present invention;

Figure 5 is a reproduction of Figure 4.2.2-1: an overview of the MAC structure according to 3GPP 38.321v17.0.0;

Figure 6 is a reproduction of Figure 4.2.2-2: an overview of the MAC structure with two MAC entities according to 3GPP 38.321v17.0.0;

Figure 7 is a reproduction of Figure 4.2.2-3: an overview of the MAC structure for side links according to 3GPP 38.321v17.0.0;

Figure 8 is a reproduction of Figure 16.9.1-1: NG-RAN architecture supporting PC5 interface according to 3GPP 38.300v17.0.0;

Figure 9 is an example according to an embodiment of the present invention, wherein the retransmission timer is not started because the HARQ feedback is not transmitted on the PUCCH during the measurement interval, so the UE may not listen to the PDCCH, and thus the UE may not be able to receive the SL grant;

Figure 10 is an example of UE1 and UE2 performing SL communication according to an embodiment of the present invention, wherein UE1 is configured with resource allocation mode 1, and NW schedules SL authorization (for new transmission) to UE1;

Figure 11 is an example according to an embodiment of the present invention, wherein the Tx UE may be instructed by the NW scheduler to transmit the SL authorization, the UE performs the SL transmission to the Rx UE (through the SL HARQ process), and the UE receives the SL HARQ feedback from the Rx UE (associated with the SL HARQ process);

Figure 12 is a flowchart of a first device according to an embodiment of the present invention, wherein the first device starts or restarts a first timer at a first symbol after the PUCCH resource, wherein the first device does not perform PUCCH transmission on the PUCCH resource due to a measurement interval;

Figure 13 is a flowchart of a first device according to an embodiment of the present invention, wherein the first device starts or restarts a first timer at a first symbol after the PUCCH resource, wherein the first device does not perform PUCCH transmission on the PUCCH resource due to an LBT failure.

Figure 14 is a flowchart of a first device according to an embodiment of the present invention. The first device starts or restarts a first timer at a first symbol after the PUCCH resource, wherein the first device performs PUCCH transmission on the PUCCH resource and receives an LBT fault indication from the physical layer of the first device.

Figure 15 is a flowchart of a first apparatus according to an embodiment of the present invention, wherein when the first apparatus fails to transmit SL HARQ feedback for the SL HARQ process on the PUCCH resource due to a measurement interval or LBT failure, the first apparatus starts or restarts a first timer for the SL HARQ process in a first symbol after the end of the PUCCH resource associated with SL authorization or SL transmission.

Detailed Implementation

The invention described herein can be applied to or implemented in the exemplary wireless communication systems and apparatus described below. Furthermore, the invention is primarily described in the context of the 3GPP architecture reference model. However, it should be understood that, with the aid of the disclosed information, those skilled in the art can readily adapt it to use and implement aspects of the invention in 3GPP2 network architectures and other network architectures.

The exemplary wireless communication systems and apparatus described below employ wireless communication systems that support broadcast services. Wireless communication systems are widely deployed to provide various types of communication, such as voice and data. These systems may be based on Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), 3GPP Long Term Evolution (LTE) radio access, 3GPP Long Term Evolution Advanced (LTE-A) radio access, 3GPP2 Ultra Mobile Broadband (UMB), WiMax, 3GPP New Radio (NR), or some other modulation techniques.

To be clear, the exemplary wireless communication systems and apparatus described below may be designed to support one or more standards, such as those provided by the alliance known herein as the 3rd Generation Partnership Project (3GPP), including: [1] 3GPP 38.321 v17.0.0; [2] 3GPP 38.331 v17.0.0; and [3] 3GPP 38.300 v17.0.0. The standards and documents listed above are hereby explicitly and entirely incorporated by reference in their entirety.

Figure 1 illustrates a multiple access wireless communication system according to an embodiment of the present invention. Access network 100 (AN) includes multiple antenna groups, one group comprising 104 and 106, another group comprising 108 and 110, and an additional group comprising 112 and 114. In Figure 1, only two antennas are shown in each antenna group; however, each antenna group may utilize more or fewer antennas. Access terminal (AT) 116 communicates with antennas 112 and 114, wherein antennas 112 and 114 transmit information to access terminal 116 on forward link 120 and receive information from access terminal 116 on reverse link 118. AT 122 communicates with antennas 106 and 108, wherein antennas 106 and 108 transmit information to AT 122 via forward link 126 and receive information from AT 122 via reverse link 124. In a Frequency Division Duplex (FDD) system, communication links 118, 120, 124, and 126 can communicate using different frequencies. For example, forward link 120 can use a different frequency than the reverse link 118.

Each antenna group and/or the area in which the antenna groups are designed to communicate is often referred to as a sector of the access network. In an embodiment, each antenna group is designed to communicate with an access terminal in a sector of an area covered by access network 100.

In communications via forward links 120 and 126, the transmit antennas of access network 100 can utilize beamforming to improve the signal-to-noise ratio of the forward links used for different access terminals 116 and 122. Furthermore, compared to an access network transmitting to all its access terminals via a single antenna, using beamforming to transmit to access terminals randomly distributed within its coverage area typically causes less interference to access terminals in adjacent cells.

AN can be a fixed station or base station used for communication with terminals, and can also be referred to as an access point, Node B, base station, enhanced base station, eNodeB, or other terms. AT can also be referred to as User Equipment (UE), wireless communication device, terminal, access terminal, or other terms.

Figure 2 is a simplified block diagram of an embodiment of a multiple input multiple output (MIMO) system 200, comprising a transmitter system 210 (also referred to as an access network) and a receiver system 250 (also referred to as an access terminal (AT) or user equipment (UE)). At the transmitter system 210, service data for multiple data streams is provided from a data source 212 to a transport (TX) data processor 214.

In one embodiment, each data stream is transmitted via a corresponding transmit antenna. The TX data processor 214 formats, encodes, and interleaves the service data of each data stream based on a specific encoding scheme selected for the data stream to provide encoded data.

OFDM technology can be used to multiplex the encoded data and pilot data of each data stream. The pilot data is typically a known data pattern processed in a known manner and can be used at the receiver system to estimate the channel response. The multiplexed pilot and encoded data of each data stream are then modulated (e.g., symbol mapped) based on a specific modulation scheme selected for the data stream (e.g., Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), Multiple Phase Shift Keying (M-PSK), or Quadrature Amplitude Modulation (M-QAM)). The data rate, encoding, and modulation of each data stream can be determined by instructions executed by processor 230. Memory 232 is coupled to processor 230.

The modulation symbols of all data streams are then provided to a TX MIMO processor 220, which can further process the modulation symbols (e.g., for OFDM). The TX MIMO processor 220 then provides N _T modulation symbol streams to N _T transmitters (TMTRs) 222a to 222t. In some embodiments, the TX MIMO processor 220 applies beamforming weights to the symbols of the data streams and to the antennas from which the symbols are being transmitted.

Each transmitter 222 receives and processes a corresponding symbol stream to provide one or more analog signals, and further modulates (e.g., amplifies, filters, and upconverts) the analog signals to provide modulated signals suitable for transmission over a MIMO channel. Subsequently, N _T modulated signals from transmitters 222a to 222t are transmitted from N _T antennas 224a to 224t, respectively.

At receiver system 250, the transmitted modulated signal is received by N _R antennas 252a to 252r, and the signal received from each antenna 252 is provided to the corresponding receiver (RCVR) 254a to 254r. Each receiver 254 modulates (e.g., filters, amplifies, and down-converts) the corresponding received signal, digitizes the modulated signal to obtain a sample, and further processes the sample to obtain the corresponding "received" symbol stream.

The RX data processor 260 then receives and processes the N _R symbol streams received from the N _R receivers 254 based on specific receiver processing techniques to obtain N _T "detected" symbol streams. The RX data processor 260 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the service data of the data stream. The processing performed by the RX data processor 260 is complementary to the processing performed by the TX MIMO processor 220 and TX data processor 214 at the transmitter system 210.

Processor 270 periodically determines which precoding matrix to use (discussed below). Processor 270 formulates a reverse link message that includes the matrix index portion and the rank portion.

The reverse link message may include various types of information about the communication link and/or the received data stream. The reverse link message is then processed by the TX data processor 238, which also receives service data from several data streams from the data source 236, modulated by the modulator 280, regulated by the transmitters 254a to 254r, and transmitted back to the transmitter system 210.

At transmitter system 210, the modulated signal from receiver system 250 is received by antenna 224, conditioned by receiver 222, demodulated by demodulator 240, and processed by RX data processor 242 to extract the reverse link message transmitted by receiver system 250. Processor 230 then determines which precoding matrix to use to determine beamforming weights and then processes the acquired message.

Memory 232 can be used to temporarily store some buffered/calculated data from 240 or 242 via processor 230, some buffered data from 212, or some specific program code. Furthermore, memory 272 can be used to temporarily store some buffered/calculated data from 260 via processor 270, some buffered data from 236, or some specific program code.

Turning to Figure 3, this figure shows an alternative simplified functional block diagram of a communication device according to an embodiment of the present invention. As shown in Figure 3, the UE (or AT) 116 and 122 in Figure 1 can be implemented using a communication device 300 in a wireless communication system, preferably an NR system. The communication device 300 may include an input device 302, an output device 304, a control circuit 306, a central processing unit (CPU) 308, a memory 310, program code 312, and a transceiver 314. The control circuit 306 executes the program code 312 in the memory 310 via the CPU 308, thereby controlling the operation of the communication device 300. The communication device 300 can receive signals input by a user through the input device 302 (e.g., a keyboard or keypad) and can output images and sounds through the output device 304 (e.g., a display or speaker). The transceiver 314 is used to receive and transmit wireless signals, transmit the received signals to the control circuit 306, and wirelessly output signals generated by the control circuit 306.

Figure 4 is a simplified block diagram of program code 312 shown in Figure 3 according to an embodiment of the present invention. In this embodiment, program code 312 includes an application layer 400, a layer 3 portion 402, and a layer 2 portion 404, and is coupled to a layer 1 portion 406. Layer 3 portion 402 typically performs radio resource control. Layer 2 portion 404 typically performs link control. Layer 1 portion 406 typically performs physical connection.

For LTE, LTE-A, or NR systems, Layer 2, Part 404 may include the Radio Link Control (RLC) layer and the Medium Access Control (MAC) layer. Layer 3, Part 402 may include the Radio Resource Control (RRC) layer.

Any two or more of the following paragraphs, (sub)bullets, points, actions, or claims described in each invention may be logically, reasonably, and appropriately combined to form a particular method.

Any sentence, paragraph, (sub)bullet, point, action, or claim described in each of the following inventions may be implemented independently and separately to form a particular method or apparatus. The use of terms such as "based on," "more precisely," and "example" in the following disclosure is merely to suggest one possible embodiment of the particular method or apparatus and does not limit its application.

In the 3GPP specification ([1] 3GPP 38.321v17.0.0), the Media Access Control (MAC) architecture, MAC reset, Discontinuous Reception (DRX), Uplink/Sidelink (UL/SL) priority ordering and Sidelink DRX are introduced:

4.2 MAC Architecture

4.2.1 Overview

This clause describes the model of MAC, but does not specify or limit the implementation method.

RRC is under the control of MAC configuration.

4.2.2 MAC Entity

The UE's MAC entity handles the following transport channels:

- Broadcast Channel (BCH);

- Downlink Shared Channel (DL-SCH);

-Paging Channel (PCH);

-Uplink Shared Channel (UL-SCH);

- Random Access Channel (RACH).

When the UE is configured with SCG, for the UE, two MAC entities are configured: one for MCG and one for SCG.

When a UE is configured with DAPS handover, two MAC entities are used by the UE: one for the source cell (source MAC entity) and one for the target cell (target MAC entity).

Unless otherwise specified, the functions of different MAC entities in the UE operate independently. Unless otherwise specified, the timers and parameters used in each MAC entity are configured independently. Unless otherwise specified, the serving cell, C-RNTI, radio bearer, logical channel, upper and lower layer entities, LCG and HARQ entities considered by each MAC entity refer to those mapped to the MAC entity.

If a MAC entity is configured with one or more SCells, then each MAC entity has multiple DL-SCHs and may have multiple UL-SCHs and multiple RACHs; for each SCell, one DL-SCH, one UL-SCH and one RACH on the SpCell, one DL-SCH, zero or one UL-SCH and zero or one RACH.

If a MAC entity is not configured with any SCell, then each MAC entity has one DL-SCH, one UL-SCH, and one RACH.

Figure 4.2.2-1 shows the possible structure of a MAC entity for each MAC entity when the SCG is not configured and during DAPS delivery.

Figure 5 is a reproduction of Figure 4.2.2-1: an overview of the MAC structure according to 3GPP 38.321v17.0.0.

Figure 4.2.2-2 shows a possible structure for a MAC entity when MCG and SCG are configured.

Figure 6 is a reproduction of Figure 4.2.2-2: an overview of the MAC structure with two MAC entities according to 3GPP 38.321v17.0.0.

In addition, the UE's MAC entity handles the following transport channels for the side link:

-Side-link shared channel (SL-SCH);

- Side-link broadcast channel (SL-BCH).

Figure 4.2.2-3 shows a possible structure for a MAC entity when a side link is configured.

Figure 7 is a reproduction of Figure 4.2.2-3: an overview of the MAC structure for side links according to 3GPP 38.321v17.0.0.

5.4.2.2 HARQ Process

…

If one of the following conditions is met, then the transmission of a MAC PDU takes precedence over sidelink transmission or can be performed simultaneously with sidelink transmission:

-If at the time of transmission there is a sidelink grant for transmission of NR sidelink communication and a configured grant for transmission of V2X sidelink communication on SL-SCH as determined in Clause 5.14.1.2.2 of TS 36.321[22], and the transmission of NR sidelink communication is not prioritized as determined in Clause 5.22.1.3.1a and the transmission of V2X sidelink communication is not prioritized as determined in Clause 5.14.1.2.2 of TS 36.321[22]; or

-If at the time of transmission there is a sidelink authorization for transmission of NR sidelink communication and a configured authorization for transmission of V2X sidelink communication on SL-SCH as defined in Clause 5.14.1.2.2 of TS 36.321[22], and the MAC entity is capable of performing this UL transmission simultaneously with the transmission of NR sidelink communication and/or the transmission of V2X sidelink communication; or

-If at the time of transmission there is only a configured authorization for transmissions of V2X sidelink communication on SL-SCH as defined in Clause 5.14.1.2.2 of TS 36.321[22], and none of the V2X sidelink communication transmissions are prioritized as defined in Clause 5.14.1.2.2 of TS 36.321[22], or the MAC entity is able to perform this UL transmission simultaneously with the V2X sidelink communication transmissions; or

- If, at the time of transmission, only a sidelink grant exists for transmissions of NR sidelink communication, and if none of the NR sidelink communication transmissions are prioritized as determined in Clause 5.22.1.3.1a, or if at the time of transmission, a sidelink grant exists for transmissions of NR sidelink communication and the MAC entity is able to perform this UL transmission concurrently with the NR sidelink communication transmission; or

-If at the time of transmission there is a sidelink grant for NR sidelink communication and a configured grant for V2X sidelink communication on the SL-SCH as determined in Clause 5.14.1.2.2 of TS 36.321[22], and only NR sidelink communication is prioritized as determined in Clause 5.22.1.3.1a or only V2X sidelink communication is prioritized as determined in Clause 5.14.1.2.2 of TS 36.321[22], and the MAC entity is capable of performing this UL transmission simultaneously with either the prioritized NR sidelink communication or the prioritized V2X sidelink communication:

5.7 Discontinuous Reception (DRX)

The MAC entity can be configured by RRC using the DRX function, wherein the DRX function controls the UE's PDCCH listening activity for the MAC entity's C-RNTI, CI-RNTI, CS-RNTI, INT-RNTI, SFI-RNTI, SP-CSI-RNTI, TPC-PUCCH-RNTI, TPC-PUSCH-RNTI, TPC-SRS-RNTI, AI-RNTI, SL-RNTI, SLCS-RNTI, and SL semi-static scheduling V-RNTI. When using DRX operation, the MAC entity shall also listen to the PDCCH in accordance with the requirements present in other clauses of this specification. When in RRC_CONNECTED, if DRX is configured, the MAC entity may use the DRX operation specified in this clause to listen to the PDCCH discontinuously for all active serving cells; otherwise, the MAC entity will listen to the PDCCH as specified in TS 38.213[6].

Note 1: Void (untyped)

RRC controls DRX operation by configuring the following parameters:

-drx-onDurationTimer: The duration at which the DRX loop begins;

-drx-SlotOffset: The delay before drx-onDurationTimer is started;

-drx-InactivityTimer: The duration following the PDCCH timing that indicates a new UL or DL transmission from the MAC entity;

-drx-RetransmissionTimerDL (per DL HARQ process, except for broadcast processes): The maximum duration until a DL retransmission is received;

-drx-RetransmissionTimerUL (per UL HARQ process): The maximum duration until a UL retransmission authorization is received;

-drx-LongCycleStartOffset: Long DRX cycle and defines the drx-StartOffset for subframes that start with long and short DRX cycles;

-drx-ShortCycle (optional): Short DRX cycle;

-drx-ShortCycleTimer (optional): The UE will follow the short DRX cycle for its duration;

-drx-HARQ-RTT-TimerDL (per DL HARQ process, except for broadcast processes): the minimum duration before the DL assignment that the MAC entity expects to retransmit the HARQ.

-drx-HARQ-RTT-TimerUL (per UL HARQ process): The minimum duration before the MAC entity expects a UL HARQ retransmission authorization;

-drx-RetransmissionTimerSL (per SL HARQ process): The maximum duration until an authorization for SL retransmission is received;

-drx-HARQ-RTT-TimerSL (per SL HARQ process): The minimum duration before the MAC entity expects the SL to retransmit authorization;

-ps-Wakeup (optional): Starts the associated drx-onDurationTimer configuration if DCP is being monitored but not detected;

-ps-TransmitOtherPeriodicCSI (optional): Configuration to report periodic CSI on PUCCH that is not L1-RSRP during the duration indicated by drx-onDurationTimer when DCP is configured but the associated drx-onDurationTimer is not started;

-ps-TransmitPeriodicL1-RSRP (optional): Configures periodic CSI for L1-RSRP to be transmitted on PUCCH for the duration indicated by drx-onDurationTimer when DCP is configured but the associated drx-onDurationTimer is not started;

-uplinkHARQ-Mode (optional): Configures the HARQ mode for each UL HARQ process.

The serving cell of a MAC entity can be configured by RRC in two DRX groups with separate DRX parameters. When RRC does not configure a secondary DRX group, only one DRX group exists, and all serving cells belong to that single DRX group. When two DRX groups are configured, each serving cell is uniquely assigned to either of the two groups. The DRX parameters configured individually for each DRX group are: drx-onDurationTimer and drx-InactivityTimer. The DRX parameters common to all DRX groups are: drx-SlotOffset, drx-RetransmissionTimerDL, drx-RetransmissionTimerUL, drx-LongCycleStartOffset, drx-ShortCycle (optional), drx-ShortCycleTimer (optional), drx-HARQ-RTT-TimerDL, drx-HARQ-RTT-TimerUL, and uplinkHARQ-Mode (optional).

When configuring DRX, the active time for the serving cell in a DRX group includes the following times:

- The drx-onDurationTimer or drx-InactivityTimer configured for the DRX group is running; or

-drx-RetransmissionTimerDL, drx-RetransmissionTimerUL, or drx-RetransmissionTimerSL are running on any serving cell in the DRX group; or

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

- The scheduling request is sent on the PUCCH and is pending (as described in Clauses 5.4.4 or 5.22.15). If this serving cell is part of a non-terrestrial network, then the active time is initiated after the first scheduling request transmission plus the UE-gNB RTT; or

- No PDCCH (as described in Clauses 5.1.4 and 5.1.4a) indicating a new transmission of C-RNTI addressed to the MAC entity is received after successful reception of a random access response for a random access preamble that was not selected by the MAC entity in the contention-based random access preamble.

When DRX is configured, the MAC entity will:

1> If a MAC PDU is received in the configured downlink assignment, then:

2> Start the drx-HARQ-RTT-TimerDL for the corresponding HARQ process in the first symbol after the corresponding transmission carrying the DL HARQ feedback has ended;

Note 1a: If the serving cell is configured with downlinkHARQ-FeedbackDisabled and DL HARQ feedback is disabled, then drx-HARQ-RTT-TimerDL will not be started for the corresponding HARQ process.

Note 1b: If this serving cell is part of a non-terrestrial network, then the latest UE-gNB RTT values will be used to set the drx-HARQ-RTT-TimerDL and drx-HARQ-RTT-TimerUL lengths before the timer starts (see TS38.331[5] Clause[X]).

2> Stop the drx-RetransmissionTimerDL process corresponding to the HARQ process.

1> If the MAC PDU is transmitted in a configured uplink grant and no LBT fault indication is received from the lower layer:

2> If this serving cell is not configured with uplinkHARQ-Mode; or

2> If this serving cell is configured with uplinkHARQ-Mode, and the corresponding HARQ process is configured with HARQ mode A, then:

3> Start the drx-HARQ-RTT-TimerUL for the corresponding HARQ process in the first symbol after the end of the first transmission (within the bundle) of the corresponding PUSCH transmission;

2> Stop the drx-RetransmissionTimerUL of the corresponding HARQ process at the first transmission (within the cluster) of the corresponding PUSCH transmission.

1> If the drx-HARQ-RTT-TimerDL expires, then:

2> If the data for the corresponding HARQ process is not successfully decoded, then:

3> After the drx-HARQ-RTT-TimerDL expires, start the drx-RetransmissionTimerDL for the corresponding HARQ process in the first symbol.

1> If drx-HARQ-RTT-TimerUL expires:

2> After the drx-HARQ-RTT-TimerUL expires, start the drx-RetransmissionTimerUL for the corresponding HARQ process in the first symbol.

1> If drx-HARQ-RTT-TimerSL expires:

2> If HARQ NACK feedback for the corresponding HARQ process is transmitted on the PUCCH; or

2> If the HARQ NACK feedback for the corresponding HARQ process is not transmitted on the PUCCH due to UL/SL priority ordering:

3> After drx-HARQ-RTT-TimerSL expires, start drx-RetransmissionTimerSL for the corresponding HARQ process in the first symbol.

2> Additionally, if the PUCCH resource is not configured and the PSFCH is configured for SL licensing, then:

3> After drx-HARQ-RTT-TimerSL expires, start drx-RetransmissionTimerSL for the corresponding HARQ process in the first symbol.

Note 1c: When sl-PUCCH-Config is configured by RRC, the UE processes the drx-RetransmissionTimerSL operation, but when sl-PUCCH-Config is not configured, PUCCH resources are not scheduled in the same way.

1> If you receive the DRX command MAC CE or the long DRX command MAC CE:

2> Stop using drx-onDurationTimer for each DRX group;

2> Stop using drx-InactivityTimer for each DRX group.

1> If the drx-InactivityTimer used for the DRX group expires, then:

2> If a short DRX cycle is configured, then:

3> After the drx-InactivityTimer expires, start or restart the drx-ShortCycleTimer for this DRX group in the first symbol;

3> Use a short DRX cycle for this DRX group.

2> Otherwise:

3> Use a long DRX loop for this DRX group.

1> If a DRX command is received via MAC CE:

2> If a short DRX cycle is configured, then:

3> Start or restart the drx-ShortCycleTimer for each DRX group in the first symbol after the DRX command MAC CE finishes receiving;

3> Use a short DRX cycle for each DRX group.

2> Otherwise:

3> Use a long DRX cycle for each DRX group.

1> If the drx-ShortCycleTimer used for the DRX group expires, then:

2> Use a long DRX loop for this DRX group.

1> If a long DRX command MAC CE is received, then:

2> Stop the drx-ShortCycleTimer used for each DRX group;

2> Use a long DRX cycle for each DRX group.

1> If a short DRX cycle is used for a DRX group, and [(SFN×10)+subframe number] modulo (drx-ShortCycle) = (drx-StartOffset) modulo (drx-ShortCycle):

2> Start the drx-onDurationTimer for this DRX group after drx-SlotOffset, starting from the subframe.

1> If a long DRX cycle is used for a DRX group, and [(SFN×10)+subframe number] modulo (drx-LongCycle) = drx-StartOffset:

2> If, as specified in Clause 10.3 of TS 38.213[6], the DL BWP is configured to listen for DCP:

3> If a DCP instruction to start drx-onDurationTimer is received from the lower layer in connection with the current DRX cycle, as specified in TS 38.213[6]; or

3> If, as specified in TS 38.213[6], all DCP opportunities in the time domain associated with the current DRX cycle occur during the active time, consider the authorization/assignment/DRX command MAC CE/long DRX command MAC CE received and the scheduling request sent (as specified in Clause 5.1.4) when the MAC entity is listening for PDCCH transmissions in the search space indicated by the recoverySearchSpaceId of the SpCell identified by C-RNTI while the ra-ResponseWindow is running; or

3> If ps-Wakeup is configured to use the value true and no DCP indication associated with the current DRX loop is received from the lower layer:

4> Start drx-onDurationTimer after drx-SlotOffset from the subframe.

2> Otherwise:

3> Start the drx-onDurationTimer for this DRX group after drx-SlotOffset, beginning from the subframe.

Note 2: In the case of an unaligned SFN spanning a carrier in a cell group, the SFN of SpCell is used to calculate the DRX duration.

1> If the DRX group is active:

2> Listen on the PDCCH of the serving cell in this DRX group as specified in TS 38.213[6];

2> If the PDCCH indicates DL transmission; or

2> If the PDCCH indicates a single HARQ feedback, as specified in Clause 9.1.4 of TS 38.213[6]; or

2> If the PDCCH instructs a retransmission of the HARQ feedback, as specified in Clause 9.1.5 of TS 38.213[6]:

3> After the corresponding transmission carrying the DL HARQ feedback is completed, start or restart the drx-HARQ-RTT-TimerDL for the corresponding HARQ process, and the HARQ feedback report of the HARQ process is in the first symbol;

Note 3: When HARQ feedback is delayed by the PDSCH-to-HARQ_feedback timing indicating that the k1 value is not applicable, as specified in TS 38.213[6], the corresponding transmission opportunity for sending DL HARQ feedback will be indicated in a later PDCCH requesting HARQ-ACK feedback.

3> Stop the drx-RetransmissionTimerDL used for the corresponding HARQ process, where HARQ feedback is reported.

3> If the PDSCH-to-HARQ_feedback timing indicator does not apply the k1 value, as specified in TS 38.213[6], then:

4> Start drx-RetransmissionTimerDL in the first symbol after the (last) PDSCH transmission (end) for the corresponding HARQ process.

2> If the PDCCH instructs the UL to transmit:

3> If this serving cell is not configured with uplinkHARQ-Mode; or

3> If this serving cell is configured with uplinkHARQ-Mode, and the corresponding HARQ process is configured with HARQ mode A, then:

4> Start the drx-HARQ-RTT-TimerUL for the corresponding HARQ process in the first symbol after the end of the first transmission (within the bundle) of the corresponding PUSCH transmission;

3> Stop the drx-RetransmissionTimerUL process corresponding to the HARQ process.

2> If PDCCH instructs SL to transmit:

3> If PUCCH resources are configured, then:

4> Start drx-HARQ-RTT-TimerSL for the corresponding HARQ process in the first symbol after the completion of the corresponding PUCCH transmission carrying SL HARQ feedback; or

4> When PUCCH is not transmitted due to UL/SL priority ordering, start drx-HARQ-RTT-TimerSL for the corresponding HARQ process in the first symbol after the end of the corresponding PSFCH resource used for SL HARQ feedback;

4> Stop the drx-RetransmissionTimerSL for the corresponding HARQ process.

3> Otherwise:

4> Start drx-HARQ-RTT-TimerSL for the corresponding HARQ process at the first symbol after the PDCCH timing ends;

4> Stop the drx-RetransmissionTimerSL for the corresponding HARQ process.

2> If the PDCCH indicates a new transmission (DL, UL, or SL) on the serving cell in this DRX group, then:

3> Start or restart the drx-InactivityTimer for this DRX group in the first symbol after the PDCCH reception ends.

Note 3a: PDCCHs indicating SPS activation, configured with authorization type 2, or configured sidelink authorization type 2 are considered to indicate new transmissions.

Note 3b: If the PDCCH reception contains two PDCCH candidates from the corresponding search space, as described in Clause 10.1 of 38.213, then the drx-InactivityTimer for this DRX group is started or restarted in the first symbol after the PDCCH candidate that ends later.

2> If the HARQ process receives downlink feedback information and indicates a response:

3> Stop the drx-RetransmissionTimerUL process corresponding to the HARQ process.

1> If, as specified in TS 38.213[6], a DCP listener is configured for the active DL BWP; and

1> If the current symbol n appears within the duration of drx-onDurationTimer; and

1> If, as specified in this clause, the drx-onDurationTimer associated with the current DRX cycle is not started:

2> If, when evaluating all the DRX activity time conditions specified in this clause, considering the authorization/assignment/DRX command MAC CE/long DRX command MAC CE received and the scheduling request sent 4ms before symbol n, the MAC entity will not be active, then:

3> Do not transmit periodic SRS and semi-static SRS, as defined in TS 38.214[7];

3> Semi-static CSI configured on the PUSCH is not reported;

3> If ps-TransmitPeriodicL1-RSRP is not configured to use the value true:

4> Do not report periodic CSIs as L1-RSRP on PUCCH.

3> If ps-TransmitOtherPeriodicCSI is not configured to have a value of true, then:

4> Do not report periodic CSIs that are not L1-RSRP on PUCCH.

1> Otherwise:

2> In the current symbol n, if, when evaluating all the DRX activity time conditions specified in this clause, the DRX group is not in active time, taking into account the grants/assignments and DRX command MACCE/long DRX command MAC CE received and the scheduling requests sent on the serving cells in this DRX group 4ms prior to symbol n; and

2> In the current symbol n, if allowCSI-SRS-Tx-MulticastDRX-Active is not configured, or when evaluating all DRX activity time conditions specified in clause 5.7b, considering the multicast allocation for MBS multicast and DRX command MAC CE received 4ms before symbol n, all multicast DRX will not be active, then:

3> Do not transmit periodic SRS and semi-persistent SRS as defined in TS 38.214[7] in this DRX group;

3> Do not report CSI on PUCCH and semi-persistent CSI configured on PUSCH in this DRX group.

2> If the CSI mask is set by the upper layer, then:

3> In the current symbol n, if, when evaluating all DRX activity timing conditions specified in this clause, the grant/assignment and DRX command MACCE/long DRX command MAC CE scheduled on the serving cell in this DRX group received 4ms prior to symbol n, the drx-onDurationTimer of the DRX group will not be running; and

4> CSI on PUCCH is not reported in this DRX group.

Note 4: If the CSI configured on the PUCCH by the UE according to the procedure multiplexing specified in Clause 9.2.5 of TS 38.213[6] is multiplexed with other UCIs, and this CSI multiplexed with other UCIs will be reported on PUCCH resources outside the DRX activity time of the DRX group in which this PUCCH is configured or outside the on-time duration period of the DRX group in which this PUCCH is configured if the CSI masking is set by the upper layer, then the UE implementation shall decide whether to report this CSI multiplexed with other UCIs.

Regardless of whether the MAC entity is listening to the PDCCH on the serving cell in the DRX group, the MAC entity will transmit HARQ feedback, aperiodic CSI on the PUSCH, and aperiodic SRS as defined in TS 38.214[7] on the serving cell in the DRX group when such a situation is expected.

If the PDCCH timing is incomplete (e.g., the activity time begins or ends in the middle of the PDCCH timing), then the MAC entity does not need to listen to the PDCCH.

5.14 Processing Measurement Intervals

During the active measurement interval, for the serving cell in the corresponding frequency range of the measurement interval configured by measGapConfig as specified in TS 38.331[5], the MAC entity will:

1> HARQ feedback, SR, and CSI transmission are not performed;

1> Do not report SRS;

1> Do not transmit on UL-SCH other than the Msg3 or MSGA payload specified in Clause 5.4.2.2;

1> If ra-ResponseWindow, ra-ContentionResolutionTimer, or msgB-ResponseWindow is running, then:

2> Listen to the PDCCH as specified in Clauses 5.1.4 and 5.1.5.

1> Otherwise:

2> Do not listen to PDCCH;

2> Do not receive on DLT-SCH.

5.21 LBT Operation

5.21.1 Overview

The lower layer may execute an LBT procedure, see TS 37.213[18], which, if the channel is identified as occupied, will prevent the lower layer from transmitting according to the LBT procedure. When the lower layer executes the LBT procedure before transmitting and when it does not transmit, an LBT fault indication is sent from the lower layer to the MAC entity. Unless otherwise specified, when an LBT procedure is executed for a transmission, the actions specified in this specification are performed regardless of whether an LBT fault indication is received from the lower layer. When the LBT is not executed by the lower layer, no LBT fault indication is received from the lower layer.

5.21.2 LBT Fault Detection and Recovery Procedure

The MAC entity can be configured by an RRC with a consistent LBT fault recovery procedure. Consistent LBT faults are detected for each UL BWP by counting LBT fault indications transmitted from the lower level to the MAC entity for all ULs.

The RRC configures the following parameters in lbt-FailureRecoveryConfig:

-lbt-FailureInstanceMaxCount for consistent LBT failure detection;

-lbt-FailureDetectionTimer for consistent LBT failure detection;

The following UE variables are used in the consistency LBT fault detection procedure:

-LBT_COUNTER (per serving cell): A counter used for LBT fault indication, initially set to 0.

For each active serving cell configured with lbt-FailureRecoveryConfig, the MAC entity will:

1> If an LBT fault indication has been received from the lower layer, then:

2> Start or restart lbt-FailureDetectionTimer;

2> Increment LBT_COUNTER by 1;

2> If LBT_COUNTER >= lbt - FailureInstanceMaxCount:

3> Trigger a consistency LBT failure for the active UL BWP in this serving cell;

3> If this serving cell is a SpCell:

4> If a consistency LBT failure has been triggered in all UL BWPs on the same carrier in the serving cell with PRACH timing configured:

5> Indicate a consistency LBT failure to the upper layer.

4> Otherwise:

5> Stop any ongoing random access procedures in this serving cell;

5> Switch the active UL BWP to a ULBWP configured with PRACH timing on the same carrier in this serving cell, and for the UL BWP, a consistency LBT failure has not yet been triggered;

5> Initiate a random access procedure (as specified in Clause 5.1.1).

1> If all triggered consistency LBT failures are eliminated in this serving cell; or

1> If the lbt-FailureDetectionTimer expires; or

1> If lbt-FailureDetectionTimer or lbt-FailureInstanceMaxCount is reconfigured by the upper layer, then:

2> Set LBT_COUNTER to 0.

MAC entities will:

1> If a consistent LBT failure has been triggered and not eliminated in SpCell; and

1> If, due to logical channel prioritization, UL-SCH resources are available for new transmissions in the SpCell and these UL-SCH resources are adaptable to LBT fault MAC CEs plus their sub-headers, then:

2> Instruction multiplexing and assembly program to generate LBT fault MAC CE.

1> Otherwise, if a consistent LBT failure has been triggered and not eliminated in at least one SCell:

2> If UL-SCH resources are available for new transmissions in the serving cell that have not yet triggered a consistency LBT failure, and due to logical channel prioritization, these UL-SCH resources can accommodate the LBT failure MAC CE plus its sub-header:

3> Instruction multiplexing and assembly program to generate LBT fault MAC CE.

2> Otherwise:

3> Trigger the scheduling request of the LBT fault MAC CE.

1> If a MAC PDU is transmitted and no LBT fault indication is received from the lower layer, and this PDU contains an LBT fault MACCE:

2> Eliminate triggered consistency LBT faults in SCell for consistency LBT faults indicated in the transmitted LBT fault MAC CE.

1> If triggering in SpCell does not eliminate the consistent LBT failure; and

1> If the random access procedure is considered to have completed successfully in SpCell (see Clause 5.1), then:

2> Eliminate triggered consistency LBT faults in SpCell.

1> If lbt-FailureRecoveryConfig is reconfigured by the upper layer used for the serving cell, then:

2> Eliminate all triggered consistency LBT faults in this serving cell.

5.22.1.3.2 PSFCH Reception

For each PSSCH transmission, the MAC entity will:

1> If a response corresponding to the PSSCH transmission in Clause 5.22.1.3.1a is obtained from the physical layer:

2> For the sidelink process, the response will be passed to the corresponding sidelink HARQ entity;

1> Otherwise:

2> For the sidelink process, the negative response will be forwarded to the corresponding sidelink HARQ entity;

1> If PSSCH is being transmitted for a pair of source layer 2IDs and destination layer 2IDs corresponding to a PC5-RRC connection already established by the upper layer:

2> Perform a HARQ-based sidelink RLF detection procedure as specified in Clause 5.22.1.3.3.

If sl-PUCCH-Config is configured by RRC, then for the timing of PUCCH transmission, the MAC entity will:

1> If the timeAlignmentTimer associated with the TAG of the serving cell that will transmit HARQ feedback stops or expires:

2> Instruct the physical layer to generate a response for the data in this TB.

1> Otherwise, if a MAC PDU has already been obtained for the sidelink authorization associated with the PUCCH transmission timing in Clause 5.22.1.3.1, then the MAC entity will:

2> If the most recent transmission of the MAC PDU is not prioritized as specified in Clause 5.22.1.3.1a:

3> According to TS 38.213[6] of Clause 16.5, the physical layer is instructed to transmit a negative response by signaling on the PUCCH.

2> Otherwise, if HARQ feedback is disabled for the MAC PDU and the next retransmission of the MAC PDU is not required; or

2> Otherwise, if the duration of all PSCCH and PSSCH for the initial transmission of a MAC PDU used for dynamic sidelink authorization or configured sidelink authorization is not within the SL DRX activity time specified in Clause 5.28.1, if the destination has data to be transmitted, then:

3> According to Clause 16.5 of TS 38.213[6], the physical layer is instructed to signal a positive response to the transmission on the PUCCH.

2> Otherwise, if HARQ feedback is disabled for the MAC PDU, and no sidelink grant is available for the next retransmission of the MAC PDU (including the duration of all PSSCH immediately following the sl-PeriodCG for sidelink grant, if the sidelink grant is configured in the sl-CG-MaxTransNumList by RRC, then the number of transmissions of the MAC PDU has not yet reached the sl-MaxTransNum corresponding to the highest priority of the logical channel in the MAC PDU) (if it exists); or

2> Otherwise, if the duration of the PSCCH and PSSCH for one or more retransmissions of a MAC PDU used for dynamic sidelink authorization or configured sidelink authorization is not within the SL DRX activity time specified in clause 5.28.1 for a destination with data to be sent, then:

3> According to Clause 16.5 of TS 38.213[6], the physical layer is instructed to signal a negative response to the transmission on the PUCCH.

2> Otherwise:

3> According to Clause 16.5 of TS 38.213[6], the physical layer is instructed to transmit a signal corresponding to the transmission on the PUCCH.

1> Otherwise:

2> According to Clause 16.5 of TS 38.213[6], the physical layer is instructed to transmit a positive response on the PUCCH by signaling.

5.22.1.3.1a Side Link Process

[...]

The transmission of the MAC PDU is prioritized over the uplink transmission of the MAC entity or other MAC entities if the following conditions are met:

1> If the MAC entity cannot simultaneously perform this-side link transmission and all uplink transmissions during transmission, and

1> If, according to TS 23.287[19], no uplink transmission is prioritized by the upper layer, and

1> If none of the NR uplink MAC PDUs contains any MAC CE that is prioritized as described in Clause 5.4.3.1.3, and

1> If ul-PrioritizationThres is configured, and if the highest priority value of all logical channels transmitted on the NR uplink is not lower than ul-PrioritizationThres, and

1> If sl-PrioritizationThres is configured, and if the highest priority value of MAC CE in the logical channel or MAC PDU is lower than sl-PrioritizationThres.

Note 2: If the MAC entity cannot perform this sidelink transmission at the same time as all uplink transmissions as specified in Clause 5.4.2.2 of TS 36.321[22], and priority ordering information is unavailable before the time of this sidelink transmission due to processing time constraints, then whether to perform this sidelink transmission depends on the UE implementation.

In the 3GPP specification ([2] 3GPP 38.331v17.0.0), SL, SL PUCCH configuration and DRX configuration were introduced:

-DRX-ConfigSL

IE DRX-ConfigSL is used to configure additional DRX parameters for the UE to perform sidelink operations in resource allocation mode 1, as specified in TS 38.321[3].

DRX-ConfigSL information element

-SL-ConfigDedicatedNR

IE SL-ConfigDedicatedNR specifies dedicated configuration information for NR side link communication.

SL-ConfigDedicatedNR information element

-MeasGapConfigIE MeasGapConfig specifies the measurement interval configuration and controls the setting/releasing of the measurement interval.

MeasGapConfig information element

-BWP-UplinkDedicated

The IE BWP-UplinkDedicated parameter is used to configure dedicated (UE-specific) parameters for the uplink BWP.

BWP-UplinkDedicated Information Element

-PUCCH-ConfigIE PUCCH-Config is used to configure the PUCCH parameters for the UE (per BWP).

PUCCH-Config information element

In the 3GPP specification ([3] 3GPP 38.300v17.0.0), a sidelink architecture was introduced:

16.9 Side Link

16.9.1 Overview

This clause provides an overview of NR sidelink communication and how NG-RAN supports NR sidelink and V2X sidelink communication. V2X sidelink communication is specified in TS 36.300[2].

The NG-RAN architecture supports the PC5 interface as shown in Figure 16.9.1-1. When the UE is within the NG-RAN coverage area, it supports sidelink transmission and reception via the PC5 interface, regardless of the UE's RRC state or when the UE is outside the NG-RAN coverage area.

Figure 8 is a reproduction of Figure 16.9.1-1: NG-RAN architecture supporting PC5 interface according to 3GPP 38.300v17.0.0.

Support for V2X services via the PC5 interface can be provided through NR sidelink communication and/or V2X sidelink communication. NR sidelink communication can be used to support other services besides V2X services.

NR sidelink communication can support one of three types of transmission modes for a pair of source layer 2IDs and destination layer 2IDs in the AS:

- Unicast transmission, characterized by:

- Supports a PC5-RRC connection between the pair of peer UEs;

- Control information and user services between peer UEs in the transmission and reception side links;

-Supports sidelink HARQ feedback;

-Supports sidelink transmission power control;

- Supports RLC AM;

- Detect radio link faults in the PC5-RRC connection.

- Multicast transmission, characterized by:

- User services belonging to a group of UEs in the transmission and reception links;

-Supports sidelink HARQ feedback.

-Broadcast transmission, characterized by:

- User services within the UE in the transmit and receive side links.

In the New Radio (NR), sidelink (SL) communication is introduced. User equipment (UE) (or devices) can perform SL communication with another UE (via unicast, multicast, and/or broadcast) on a sidelink interface (e.g., PC5). UEs can transmit SL data to and/or receive SL data from other UEs with or without network (NW) instructions. In Release 17, discontinuous SL reception is introduced for sidelink devices for power saving, thereby discontinuously listening to the Physical Sidelink Shared Channel (PSSCH) and/or Sidelink Control Information (SCI) on the sidelink channel. In discontinuous SL reception (DRX), several timers are introduced for the UE to derive the active time on the SL for listening to the SCI:

-sl-drx-onDurationTimer: The duration at which the SL DRX cycle begins;

-sl-drx-SlotOffset: The delay before starting sl-drx-onDurationTimer;

-sl-drx-InactivityTimer (the difference being broadcast transmission): The duration following the first time slot of the SCI reception (i.e., Level 1 SCI and Level 2 SCI), where the SCI indicates a new SL transmission for the Media Access Control (MAC) entity.

-sl-drx-RetransmissionTimer (for each link process, the difference being broadcast transmission): the maximum duration until a retransmission is received from the SL;

-sl-drx-StartOffse: The slot at which the SL DRX loop begins;

-sl-drx-Cycle: Sidelink DRX Cycle;

-sl-drx-HARQ-RTT-Timer (for each link process, the difference being broadcast transmission): The minimum duration expected by the MAC entity before the SL Hybrid Automatic Repeat Request (HARQ) is retransmitted.

The UE may configure one or more of the above timers via dedicated signaling from the network (e.g., SL-ConfigDedicatedNR) and/or via (broadcast) system information (e.g., SIB12) and/or via PC5-Radio Resource Control (RRC) signaling (e.g., RRCReconfigurationSidelink) to a transmitter UE (e.g., transmitter (Tx) UE). One or more timers may be associated with unicast, multicast, and/or broadcast. The UE may maintain or configure a set of one or more timers for PC5 connectivity (e.g., per destination (ID)). Alternatively, the UE may maintain or configure different sets of one or more timers for SL data with different Quality of Service (QoS) or different priorities.

For SL transmission, the UE can be configured with resource allocation mode 1 (e.g., network scheduling mode, SL communication based on network scheduling, configured with sl-ScheduledConfig) and/or resource allocation mode 2 (autonomous resource selection mode, configured with sl-UE-SelectedConfig).

To receive SL communication scheduling from the network, the UE may configure a timer associated with a Uu interface, which is associated with sidelink operations performed in resource allocation mode 1. The timer may include drx-HARQ-RoundTrip Time (RTT)-TimerSL and drx-RetransmissionTimerSL. When or if the UE receives a Physical Downlink Control Channel (PDCCH) indicating SL transmission, after the transmission of the corresponding Physical Uplink Control Channel (PUCCH) carrying HARQ feedback (e.g., HARQ Negative Acknowledgment (NACK) feedback or negative acknowledgment), or when the PUCCH transmission is not transmitted due to uplink (UL)/SL priority ordering, the UE may initiate drx-HARQ-RTT-TimerSL for the corresponding HARQ process in the first symbol. After drx-HARQ-RTT-TimerSL expires, the UE may initiate drx-RetransmissionTimerSL for the corresponding HARQ process. When drx-RetransmissionTimerSL is running, the UE can listen to the PDCCH on the serving cell (e.g., to receive the scheduled SL authorization for retransmission).

The UE can be configured with measurement intervals for one or more serving cells (e.g., via measGapConfig). During an active measurement interval, the UE does not transmit HARQ feedback. This includes not transmitting HARQ feedback associated with the SL transmission on the PUCCH. However, the network may deem a retransmission necessary (e.g., due to the lack of a positive feedback) and schedule a retransmission SL grant to the UE. Because the HARQ feedback is not transmitted on the PUCCH during the measurement interval, the retransmission timer is not started, causing the UE to potentially not listen to the PDCCH, and therefore the UE may not receive the SL grant. An example of the problem is illustrated in Figure 9. UE1 performs SL communication with UE2. UE1 is configured with resource allocation mode 1. The NW schedules an SL grant (for the new transmission) to UE1. At time t1, UE1 performs an SL data transmission to UE2. UE2 fails to decode the data and at time t2 transmits an SL HARQ feedback indicating a negative acknowledgment (NACK) to UE1. At time t4, UE1 is configured or equipped with PUCCH resources associated with SL transmissions and/or SL HARQ feedback on Uu (e.g., via downlink control information (DCI) associated with SL grants or via sidelink configuration grant indication). UE1 is configured with a measurement interval configuration, and the active measurement interval is during t3 and t3+n. UE1 does not perform PUCCH transmissions via PUCCH resources (to indicate negative acknowledgments). Since UE1 does not start a DRX timer (e.g., a HARQ-RTT timer or a retransmission timer), UE1 may not listen to the PDCCH when the network provides SL grants for retransmissions of SL transmissions.

Furthermore, the UE can operate on unlicensed spectrum, and can perform Listen-Before-Speak (LBT) operation to perform transmissions on unlicensed spectrum. If the UE experiences an LBT failure and fails to transmit the HARQ feedback associated with the SL, the UE may be unable to receive the SL retransmission authorization for the corresponding HARQ process because the timer has not been started. In this invention, when the feedback associated with the SL is not transmitted on the PUCCH, a method is introduced for the UE to start a Uu DRX timer to listen to the PDCCH.

One concept or aspect of the present invention is that when a PUCCH transmission associated with a PUCCH resource is not transmitted due to an (active) measurement interval, the UE may start or restart a first timer (for the HARQ process) after the PUCCH resource ends (in a first symbol). The PUCCH resource and/or PUCCH transmission may be located within or occur within the measurement interval. The UE may start the first timer in the first symbol following the PUCCH resource.

Additionally and/or alternatively, (when or if the HARQ feedback associated with the first timer indicates a negative acknowledgment transmitted by the SL), the UE may start or restart a second timer in response to the expiration of the first timer. The UE may start or restart the second timer in the first symbol after the first timer has expired. Additionally and/or alternatively, when or if the HARQ feedback associated with the first timer indicates a positive acknowledgment transmitted by the SL, the UE may not start or restart the second timer when the first timer expires. If or when the first timer expires, and if or if the HARQ feedback associated with the first timer is not transmitted on the PUCCH due to a measurement interval, the UE may start or restart the second timer. The HARQ feedback may be carried, included, or indicated in a PUCCH transmission associated with PUCCH resources.

PUCCH transmissions can be associated with SL transmissions. The UE can perform SL communication with a second UE. The UE can be a transmitter (Tx) UE for the SL transmission, and the second UE can be a receiver (Rx) UE for the SL transmission. SL transmissions can be transmissions on the PC5 interface (and not on the Uu interface, nor transmitted to/from the network). PUCCH transmissions can be HARQ feedback associated with the SL transmission. PUCCH transmissions can be associated with transmission/reception results associated with the SL transmission. PUCCH transmissions can not be associated with transmission/reception results of downlink (DL) reception or UL transmissions. PUCCH transmissions can indicate positive acknowledgments. If or when the UE receives a negative acknowledgment (e.g., NACK or indication of unsuccessful reception of the SL transmission) from the second UE, the UE can indicate a negative acknowledgment (or SL HARQ NACK) in the PUCCH transmission (to the network). Alternatively, if or when the UE determines that a retransmission of the SL data (in the SL transmission) is required, the UE can indicate a negative acknowledgment (or SL HARQ NACK) in the PUCCH transmission (to the network). Additionally and/or alternatively, if or when the UE does not receive an acknowledgment associated with the SL transmission (from a second UE), the UE may indicate a negative acknowledgment (or SL HARQ NACK) in the PUCCH transmission (to the network). Alternatively, the PUCCH transmission may indicate a positive acknowledgment.

An example is illustrated in Figure 10. UE1 performs SL communication with UE2. UE1 is configured with resource allocation mode 1. NW schedules SL grant (for new transmission) to UE1. At time t1, UE1 performs SL data transmission to UE2. UE2 fails to decode the data and at time t2 transmits SL HARQ feedback indicating a negative acknowledgment (NACK) to UE1. At time t4, UE1 is configured or equipped with PUCCH resources associated with SL transmission and/or SL HARQ feedback on Uu (e.g., via DCI associated with SL grant or via sidelink configuration grant configuration indication). UE1 is configured with a measurement interval configuration, and the active measurement interval is during t3 and t3+n. UE1 does not perform PUCCH transmission (for indicating a negative acknowledgment) via PUCCH resources. (When PUCCH is not transmitted due to measurement interval) UE1 initiates drx-HARQ-RTT-TimerSL for the corresponding HARQ process (for SL transmission) in the first symbol after the PUCCH resource. In response to the expiration of drx-HARQ-RTT-TimerSL, the UE initiates drx-RetransmissionTimerSL (for the corresponding HARQ process). At time t5, the network schedules SL grants (for retransmissions associated with SL data transmissions). While drx-RetransmissionTimerSL is running, the UE listens to the PDCCH associated with the network.

Additionally and/or alternatively, when a PUCCH transmission associated with a PUCCH resource is not transmitted due to an LBT failure (as associated with the PUCCH transmission), the UE may start or restart a first timer (for the HARQ process) after the PUCCH resource ends (in the first symbol). The UE's MAC entity may receive an LBT failure indication (e.g., from the UE's lower layer). Additionally and/or alternatively, when a PUCCH transmission is transmitted and an LBT failure indication (as associated with the PUCCH transmission) is received from a lower layer (e.g., the UE's physical layer), the UE may start or restart a first timer (for the HARQ process) after the PUCCH resource ends.

Additionally and/or alternatively, (when or if the HARQ feedback associated with the first timer indicates a negative acknowledgment of the SL transmission), if or when a PUCCH transmission is transmitted and the UE receives an LBT fault indication (as associated with the PUCCH transmission), the UE may start or restart the second timer after the first timer expires (in the first symbol). Additionally and/or alternatively, when or if the HARQ feedback associated with the first timer indicates a positive acknowledgment of the SL transmission, the UE may not start or restart the second timer upon the expiration of the first timer. The HARQ feedback may be carried, included, or indicated in the PUCCH transmission associated with the PUCCH resource.

Additionally and/or alternatively, Figure 11 illustrates another example. The Tx UE can indicate the SL grant for the SL transmission via NW scheduling. The UE performs the SL transmission to the Rx UE (via the SL HARQ process). The UE receives SL HARQ feedback (as associated with the SL HARQ process) from the Rx UE. The SL HARQ feedback can be a negative acknowledgment (indicating unsuccessful decoding of the SL transmission). The Tx UE can cause and/or instruct its physical layer to signal a negative acknowledgment (as SL HARQ feedback associated with the SL transmission) on the PUCCH associated with the SL grant and/or SL transmission (e.g., the timeslot position of the PUCCH resource can be indicated in the DCI associated with the SL grant). The UE may be unable to transmit the PUCCH due to a measurement interval and/or LBT failure (indicating a negative acknowledgment). When the PUCCH is not transmitted due to a measurement interval or LBT failure, the Tx UE initiates drx-HARQ-RTT-TimerSL in the first symbol after the end of the PUCCH resource. In response to the expiration of drx-HARQ-RTT-TimerSL and a NACK response from the SL HARQ on the PUCCH, the Tx UE starts drx-RetransmissionTimerSL. While drx-RetransmissionTimerSL is running, the Tx UE can listen to the PDCCH (or be in DRX active time).

The concepts and examples disclosed above may be implemented, executed, added to, or included in the following aspects and embodiments.

In various embodiments, the first timer can be used to control when the second timer is started or restarted. The first timer can be used to estimate round-trip time, such as the round-trip time between the first UE and the network (of the first device).

In various embodiments, a second timer can be used to control the timing of PDCCH listening (for the (first) UE), for example, to receive SL grants for retransmission of SL transmissions. The (first) UE can listen to the PDCCH while the second timer is running. The activity time of the serving cell in the DRX group associated with the second timer may include the time during which the second timer is running.

In various embodiments, the UE may be configured with sidelink resource allocation mode-1 (e.g., sl-ScheduledConfig). The UE may not be configured with sidelink resource allocation mode-2 (e.g., sl-ueselectconfig).

In various embodiments, the first timer may be drx-HARQ-RTT-TimerSL.

In various embodiments, the UE may be configured with PUCCH resources (e.g., sl-PUCCH-config) for indicating the results of SL transmission.

In various embodiments, the second timer may be drx-RetransmissionTimerSL.

In various embodiments, the PUCCH transmission may be a HARQ NACK feedback for the corresponding HARQ process. Alternatively, the PUCCH transmission may be a HARQ ACK feedback (e.g., a positive ACK) for the corresponding HARQ process.

All concepts, embodiments, and examples described above and in this document may be combined into new concepts and/or combinations of new concepts.

Referring to FIG12, according to this and other concepts, systems and methods of the present invention, a method 1000 for a first device in a wireless communication system includes: being instructed or configured with a DRX configuration associated with an SL, wherein the DRX configuration indicates one or more timers associated with PDCCH listening (step 1002); starting or restarting a first timer at a first symbol following a PUCCH resource, wherein the first device does not perform PUCCH transmission on the PUCCH resource due to a measurement interval (step 1004); starting or restarting a second timer at a first symbol after the second timer expires (step 1006); and listening to the PDCCH while the second timer is running (step 1008).

Referring back to Figures 3 and 4, in one or more embodiments viewed from the perspective of the first device, device 300 includes program code 312 stored in memory 310 of the transmitter. CPU 308 is executable program code 312 to: (i) be instructed or configured with a DRX configuration associated with SL, wherein the DRX configuration indicates one or more timers associated with PDCCH listening; (ii) start or restart a first timer at a first symbol following the PUCCH resource, wherein the first device has not performed a PUCCH transmission on the PUCCH resource due to a measurement interval; (iii) start or restart a second timer at a first symbol after the second timer expires; and (iv) listen to the PDCCH while the second timer is running. Furthermore, CPU 308 is executable program code 312 to perform all the described actions, steps, and methods described above, below, or otherwise herein.

Referring to FIG13, according to this and other concepts, systems and methods of the present invention, a method 1010 for a first device in a wireless communication system includes: being instructed or configured with a DRX configuration associated with an SL, wherein the DRX configuration indicates one or more timers associated with PDCCH listening (step 1012); starting or restarting a first timer at a first symbol after a PUCCH resource, wherein the first device fails to perform PUCCH transmission on the PUCCH resource due to an LBT failure (step 1014); starting or restarting a second timer at a first symbol after the second timer expires (step 1016); and listening to the PDCCH while the second timer is running (step 1018).

Referring back to Figures 3 and 4, in one or more embodiments viewed from the perspective of the first device, device 300 includes program code 312 stored in memory 310 of the transmitter. CPU 308 is executable program code 312 to: (i) be instructed or configured with a DRX configuration associated with SL, wherein the DRX configuration indicates one or more timers associated with PDCCH listening; (ii) start or restart a first timer at a first symbol following the PUCCH resource, wherein the first device does not perform PUCCH transmission on the PUCCH resource due to an LBT failure; (iii) start or restart a second timer at a first symbol after the second timer expires; and (iv) listen to the PDCCH while the second timer is running. Furthermore, CPU 308 is executable program code 312 to perform all the described actions, steps, and methods described above, below, or otherwise herein.

Referring to FIG14, according to this and other concepts, systems and methods of the present invention, a method 1020 for a first device in a wireless communication system includes: being instructed or configured with a DRX configuration associated with an SL, wherein the DRX configuration indicates one or more timers associated with PDCCH listening (step 1022); starting or restarting a first timer at a first symbol after a PUCCH resource, wherein the first device performs a PUCCH transmission on the PUCCH resource and receives an LBT fault indication from the physical layer of the first device (step 1024); starting or restarting a second timer at a first symbol after the second timer expires (step 1026); and listening to the PDCCH while the second timer is running (step 1028).

Referring back to Figures 3 and 4, in one or more embodiments viewed from the perspective of the first device, device 300 includes program code 312 stored in memory 310 of the transmitter. CPU 308 is executable program code 312 to: (i) be instructed or configured with a DRX configuration associated with SL, wherein the DRX configuration indicates one or more timers associated with PDCCH listening; (ii) start or restart a first timer at a first symbol following the PUCCH resource, wherein the first device performs a PUCCH transmission on the PUCCH resource and receives an LBT fault indication from the physical layer of the first device; (iii) start or restart a second timer at a first symbol after the second timer expires; and (iv) listen to the PDCCH while the second timer is running. Furthermore, CPU 308 is executable program code 312 to perform all the described actions, steps, and methods described above, below, or otherwise herein.

In the various embodiments disclosed above and herein, the first device performs SL data transmission to the second device, wherein the second device transmits SL HARQ feedback to the first device on the PC5 interface or on a side link.

In the various embodiments disclosed above and herein, if or when SL data needs to be retransmitted, the first device instructs the physical layer of the first device to generate a negative response to the PUCCH transmission on the PUCCH resource.

In the various embodiments disclosed above and herein, the first device instructs its physical layer to generate a positive or negative response for a PUCCH transmission on a PUCCH resource based on SL HARQ feedback associated with SL data from the second device.

In the various embodiments disclosed above and herein, the first device does not listen to the PDCCH while the first timer is running.

In the various embodiments disclosed above and herein, the first timer is drx-HARQ-RTT-TimerSL.

In the various embodiments disclosed above and herein, the second timer is drx-RetransmissionTimerSL.

In the various embodiments disclosed above and herein, the PUCCH transmission is a HARQ NACK feedback associated with the SL transmission from the first device to the second device.

In the various embodiments disclosed above and herein, the PUCCH transmission is a HARQ ACK feedback associated with the SL transmission from the first device to the second device.

Referring to FIG15, according to this and other concepts, systems and methods of the present invention, method 1030 for a first device (e.g., a first UE) in a wireless communication system includes: receiving an SL grant (from the network), wherein the SL grant indicates an SL transmission (step 1032); when the first device fails to transmit an SLHARQ feedback for the SL HARQ process on the PUCCH resource due to a measurement interval or LBT failure, starting or restarting a first timer for the SL HARQ process in a first symbol after the end of the PUCCH resource associated with the SL grant or SL transmission (step 1034); when the first device fails to transmit an SL HARQ feedback for the SL HARQ process on the PUCCH resource due to a measurement interval or LBT failure and the SL HARQ feedback is NACK, starting or restarting a second timer for the SL HARQ process in a first symbol after the expiration of the first timer (step 1036); and listening to the PDCCH while the second timer is running (step 1038).

In various embodiments, the method further includes performing SL transmission to a second device (e.g., a second UE) via an SL HARQ process.

In various embodiments, the method further includes receiving SL HARQ feedback from a second device for SL transmission.

In various embodiments, the SL HARQ feedback used for SL transmission is NACK.

In various embodiments, the method further includes determining SL HARQ feedback for the SL HARQ process based on SL HARQ feedback (received from the second device) for SL transmission.

In various embodiments, the method further includes instructing the physical layer of the first device to signal a negative response on the PUCCH resource if or when the SL transmission needs to be retransmitted.

In various embodiments, the first timer is drx-HARQ-RTT-TimerSL.

In various embodiments, the second timer is drx-RetransmissionTimerSL.

In various embodiments, the first device is configured with PUCCH resources for transmitting SL HARQ feedback for the SL HARQ process.

In various embodiments, the first device is instructed or configured with a DRX configuration associated with the SL, wherein the DRX configuration indicates one or more timers, including a first timer and a second timer, associated with PDCCH monitoring.

Referring back to Figures 3 and 4, in one or more embodiments viewed from the perspective of the first device, device 300 includes program code 312 stored in memory 310 of the transmitter. CPU 308 executes program code 312 to: (i) receive an SL grant, wherein the SL grant indicates an SL transmission; (ii) when the first device fails to transmit SL HARQ feedback for the SL HARQ process on the PUCCH resource due to a measurement interval or LBT failure, start or restart a first timer for the SL HARQ process in a first symbol after the end of the PUCCH resource associated with the SL grant or SL transmission; (iii) when the first device fails to transmit SL HARQ feedback for the SL HARQ process on the PUCCH resource due to a measurement interval or LBT failure and the SL HARQ feedback is NACK, start or restart a second timer for the SL HARQ process in a first symbol after the expiration of the first timer; and (iv) while the second timer is running, listen to the PDCCH. In addition, CPU 308 can execute program code 312 to perform all the described actions, steps and methods described above, below or otherwise herein.

The following presents various embodiments disclosed herein and possible textual proposals for the 3GPP MAC specification based on [1] 3GPP 38.321v17.0.0:

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5.28 Sidelink Discontinuous Receiver (DRX)

[...]

2> If PDCCH instructs SL to transmit:

3> If PUCCH resources are configured, then:

4> Start drx-HARQ-RTT-TimerSL for the corresponding HARQ process in the first symbol after the completion of the corresponding PUCCH transmission carrying SL HARQ feedback; or

4> When the PUCCH is not transmitted due to UL/SL priority ordering, measurement interval, or LBT fault indication , start drx-HARQ-RTT-TimerSL for the corresponding HARQ process in the first symbol after the end of the corresponding PUCCH resource used for SLHARQ feedback;

4> Stop the drx-RetransmissionTimerSL for the corresponding HARQ process.

[...]

=== ...

=== ...

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5.28 Sidelink Discontinuous Receiver (DRX)

[...]

1> If drx-HARQ-RTT-TimerSL expires:

2> If HARQ NACK feedback for the corresponding HARQ process is transmitted on the PUCCH; or

2> If the HARQ NACK feedback for the corresponding HARQ process is not transmitted on the PUCCH due to UL/SL priority ordering, measurement interval, or LBT fault indication , then:

3> After drx-HARQ-RTT-TimerSL expires, start drx-RetransmissionTimerSL for the corresponding HARQ process in the first symbol.

2> Additionally, if the PUCCH resource is not configured and the PSFCH is configured for SL licensing, then:

3> After drx-HARQ-RTT-TimerSL expires, start drx-RetransmissionTimerSL for the corresponding HARQ process in the first symbol.

[...]

=== ...

=== ...

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5.28 Sidelink Discontinuous Receiver (DRX)

[...]

2> If PDCCH instructs SL to transmit:

3> If PUCCH resources are configured, then:

4> Start drx-HARQ-RTT-TimerSL for the corresponding HARQ process in the first symbol after the completion of the corresponding PUCCH transmission carrying SL HARQ feedback; or

4> When PUCCH is not transmitted due to UL/SL priority ordering or measurement interval , start drx-HARQ-RTT-TimerSL for the corresponding HARQ process in the first symbol after the end of the corresponding PSFCH resource for SL HARQ feedback;

4> Stop the drx-RetransmissionTimerSL for the corresponding HARQ process.

[...]

=== ...

=== ...

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5.28 Sidelink Discontinuous Receiver (DRX)

[...]

1> If drx-HARQ-RTT-TimerSL expires:

2> If HARQ NACK feedback for the corresponding HARQ process is transmitted on the PUCCH; or

2> If the HARQ NACK feedback for the corresponding HARQ process is not transmitted on the PUCCH due to UL/SL priority ordering or measurement interval , then:

3> After drx-HARQ-RTT-TimerSL expires, start drx-RetransmissionTimerSL for the corresponding HARQ process in the first symbol.

2> Additionally, if the PUCCH resource is not configured and the PSFCH is configured for SL licensing, then:

3> After drx-HARQ-RTT-TimerSL expires, start drx-RetransmissionTimerSL for the corresponding HARQ process in the first symbol.

[...]

=== ...

Any combination of the concepts or teachings above may be combined together or formed into new embodiments. The disclosed details and embodiments may be used to solve at least (but not limited to) the problems mentioned above and herein.

It should be noted that any of the methods, alternatives, steps, examples, and embodiments presented herein may be used independently, individually, and/or in combination with multiple methods, alternatives, steps, examples, and embodiments.

Various aspects of this disclosure have been described above. It should be understood that the teachings herein can be embodied in a wide variety of forms, and any specific structure, function, or both disclosed herein are merely representative. Based on the teachings herein, those skilled in the art will understand that the aspects disclosed herein can be implemented independently of any other aspects, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement an apparatus or practice. Furthermore, such apparatuses or practices can be implemented using structures, functions, or structures and functions different from those set forth herein, in addition to one or more aspects. As examples of some of the foregoing concepts, in some aspects a parallel channel can be established based on the pulse repetition frequency. In some aspects a parallel channel can be established based on the pulse position or offset. In some aspects a parallel channel can be established based on a time-hopping sequence. In some aspects a parallel channel can be established based on the pulse repetition frequency, the pulse position or offset, and the time-hopping sequence.

Those skilled in the art will understand that information and signals can be represented using any of a variety of different techniques and skills. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, or any combination thereof.

Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, processors, components, circuits, and algorithm steps described in conjunction with the aspects disclosed herein can be implemented as electronic hardware (e.g., digital implementations, analog implementations, or a combination of both, which may be designed using source decoding or some other technique) and have instructions in various forms of program or design code (which, for convenience, may be referred to herein as "software" or "software module") or a combination of both. To clearly illustrate this interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps have been described above in general terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the system as a whole. Those skilled in the art may implement the described functionality in different ways for each specific application, but such implementation decisions should not be construed as causing a departure from the scope of this disclosure.

Additionally, the various illustrative logic blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented within, or executed by, an integrated circuit (“IC”), an access terminal, or an access point. An IC may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, electrical components, optical components, mechanical components, or any combination thereof designed to perform the functions described herein, and may execute code or instructions residing within, outside, or both of the IC. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors incorporating a DSP core, or any other such configuration.

It should be understood that any particular order or hierarchy of steps in any disclosed process is an instance of an example method. It should be understood that a particular order or hierarchy of steps in the process may be rearranged based on design preferences while remaining within the scope of this disclosure. The appended method claims present the elements of the various steps in an exemplary order and are not intended to limit us to the particular order or hierarchy presented.

The steps of the methods or algorithms described in conjunction with the aspects disclosed herein can be implemented directly in hardware, in a software module executed by a processor, or a combination of both. The software module (e.g., containing executable instructions and associated data) and other data can reside in a data memory, such as RAM, flash memory, ROM, EPROM, EEPROM, registers, hard disk, removable disk, CD-ROM, or any other form of computer-readable storage media known in the art. Example storage media can be coupled to a machine such as a computer/processor (which may be referred to herein as a "processor"), which can read information (e.g., code) from and write said information to the storage media. Example storage media can be integrated with the processor. The processor and storage media can reside in an ASIC. The ASIC can reside in a user equipment. Alternatively, the processor and storage media can reside as discrete components in the user equipment. Furthermore, in some aspects, any suitable computer program product may include a computer-readable medium comprising code associated with one or more aspects of this disclosure. In some respects, computer program products may include packaging materials.

While the invention has been described in conjunction with various aspects, it should be understood that further modifications are possible. This application is intended to cover any changes, uses, or adaptations to the invention that generally follow the principles of the invention and include such deviations from this disclosure, which fall within the scope of known and common practice in the field to which this invention pertains.

Claims (20)

1. A method for a first apparatus, comprising: Receive side link (SL) authorization, wherein the SL authorization instructs SL transmission; In response to determining that the first device has not transmitted SL HARQ feedback for the SL HARQ process on the PUCCH resource due to a measurement interval or a Listen-After-Speak (LBT) failure, a first timer for the SL Hybrid Automatic Repeat Request (HARQ) process is started or restarted in the first symbol after the end of the Physical Uplink Control Channel (PUCCH) resource associated with the SL grant or the SL transmission. In response to determining that the first device failed to transmit the SL HARQ feedback for the SL HARQ process on the PUCCH resource due to the measurement interval or the LBT failure, and that the SL HARQ feedback was a negative acknowledgment (NACK), a second timer for the SL HARQ process is started or restarted in a first symbol after the first timer expires; and In response to determining that the second timer is running, the Physical Downlink Control Channel (PDCCH) is monitored. 2. The method of claim 1, further comprising performing the SL transmission to a second device via the SL HARQ process. 3. The method of claim 1, further comprising receiving SL HARQ feedback from the second device for the SL transmission. 4. The method of claim 3, wherein the SL HARQ feedback for the SL transmission is NACK. 5. The method of claim 3, further comprising determining the SL HARQ feedback for the SL HARQ process based on the SL HARQ feedback used for the SL transmission. 6. The method of claim 1, further comprising instructing the physical layer of the first device to signal a NACK on the PUCCH resource if or when the SL transmission requires retransmission. 7. The method of claim 1, wherein the first timer is drx-HARQ-RTT-TimerSL. 8. The method of claim 1, wherein the second timer is drx-RetransmissionTimerSL. 9. The method of claim 1, wherein the first device is configured to transmit the PUCCH resource for transmitting the SL HARQ feedback for the SL HARQ process. 10. The method of claim 1, wherein the first device is instructed or configured with a discontinuous reception (DRX) configuration associated with the SL, wherein the DRX configuration indicates a plurality of timers including the first timer and the second timer associated with the PDCCH eavesdropping. 11. A first device, comprising: Memory; and A processor, operatively coupled to the memory, wherein the processor is configured to execute program code to: Receive side link (SL) authorization, wherein the SL authorization instructs SL transmission; In response to determining that the first device has not transmitted SL HARQ feedback for the SL HARQ process on the PUCCH resource due to a measurement interval or a Listen-After-Speak (LBT) failure, a first timer for the SL Hybrid Automatic Repeat Request (HARQ) process is started or restarted in the first symbol after the end of the Physical Uplink Control Channel (PUCCH) resource associated with the SL grant or the SL transmission. In response to determining that the first device failed to transmit the SL HARQ feedback for the SL HARQ process on the PUCCH resource due to the measurement interval or the LBT failure, and that the SL HARQ feedback is a negative acknowledgment (NACK), a second timer for the SL HARQ process is started or restarted in a first symbol after the first timer expires; and In response to determining that the second timer is running, the Physical Downlink Control Channel (PDCCH) is monitored. 12. The first apparatus of claim 11, wherein the processor is further configured to execute program code to perform the SL transfer to the second apparatus via the SL HARQ process. 13. The first apparatus of claim 11, wherein the processor is further configured to execute program code to receive SL HARQ feedback for the SL transfer from the second apparatus. 14. The first apparatus of claim 13, wherein the SL HARQ feedback for the SL transmission is NACK. 15. The first apparatus of claim 13, wherein the processor is further configured to execute program code to determine the SL HARQ feedback for the SL HARQ process based on the SL HARQ feedback for the SL transfer. 16. The first apparatus of claim 11, wherein the processor is further configured to execute program code to instruct the physical layer of the first apparatus to signal a NACK on the PUCCH resource if or when the SL transmission requires retransmission. 17. The first apparatus of claim 11, wherein the first timer is drx-HARQ-RTT-TimerSL. 18. The first apparatus of claim 11, wherein the second timer is drx-RetransmissionTimerSL. 19. The first apparatus of claim 11, wherein the first apparatus is configured to transmit the PUCCH resources for transmitting the SL HARQ feedback for the SL HARQ process. 20. The first apparatus of claim 11, wherein the first apparatus is indicated or configured with a discontinuous reception (DRX) configuration associated with the SL, wherein the DRX configuration indicates a plurality of timers including the first timer and the second timer associated with the PDCCH eavesdropping.