Method and apparatus for harq codebook construction

Abstract

A method performed by a user equipment, comprising receiving a first sidelink (SL) physical downlink control channel (PDCCH) from a base station (BS), wherein the first SL PDCCH provides scheduling information for at least one SL transmission; obtaining a value of a sidelink assignment indication (SAI) field from the first SL PDCCH, wherein the value of the SAI field indicates a first cumulative number of received SL PDCCHs up to the first SL PDCCH; and constructing a hybrid automatic repeat request (HARQ) codebook for a first number of SL transmissions scheduled by a second number of second received SL PDCCHs; wherein the HARQ codebook is transmitted from the user equipment to the BS, the first number of SL transmissions includes the at least one SL transmission, the second received SL PDCCHs include the first received SL PDCCH, and the first received SL PDCCH includes the first SL PDCCH.

Description

Technical Field

[0001] This application claims priority to U.S. Provisional Application No. 62 / 909,948, filed on October 3, 2019, entitled "HARQ Feedback for Sidelink Resource Allocation for Uu Control" (hereinafter referred to as "'948 Provisional Application"), the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a wireless communication, and more specifically, to a method and apparatus for constructing a Hybrid Automatic Repeat reQuest (HARQ) codebook. Background Technology

[0003] With the number of connected devices increasing dramatically and user / network (NW) traffic growing rapidly, the industry has made various efforts to improve different aspects of wireless communication in next-generation wireless communication systems, such as fifth-generation (5G) new radio (NR), which has improvements in data rate, latency, reliability and mobility.

[0004] The new 5G radio system is designed to provide flexibility and configurability to optimize network services and types to suit a variety of use cases, such as Enhanced Mobile Broadband (eMBB), Massive Machine-Type Communication (mMTC), and Ultra-Reliable and Low-Latency Communication (URLLC).

[0005] However, with the continued increase in demand for radio access, there is a need to further improve wireless communication for constructing hybrid automatic repeat request codebooks related to sidelink (SL) transmissions. Summary of the Invention

[0006] This invention relates to a method and apparatus for constructing a hybrid automatic repeat request codebook.

[0007] One aspect of the present invention is to provide a method performed by a user equipment (UE). The method includes receiving a first sidelink (SL) entity downlink control channel (PDCCH) from a base station (BS), wherein the first SL PDCCH provides scheduling information for at least one sidelink transmission; obtaining a value of a sidelink allocation indicator (SAI) field from the first SL PDCCH, wherein the value of the SAI field indicates the cumulative number of a first received SL PDCCH up to the first SL PDCCH; and constructing a hybrid automatic repeat request (HARQ) codebook for a first number of SL transmissions scheduled by a second number of a second received SL PDCCH; wherein the HARQ codebook is sent from the UE to the base station, the first number of SL transmissions includes at least one SL transmission, the second received SL PDCCH includes the first received SL PDCCH, and the first received SL PDCCH includes the first SL PDCCH.

[0008] Another aspect of the present invention provides a user equipment (UE) in a wireless communication system including a base station (BS). The UE includes a memory and at least one processor coupled to the memory. The at least one processor is configured to receive from the base station (BS) a first sidelink (SL) entity downlink control channel (PDCCH), wherein the first SL PDCCH provides scheduling information for at least one sidelink transmission; obtain a value of a sidelink allocation indication (SAI) field from the first SL PDCCH, wherein the value of the SAI field indicates the cumulative number of first received SL PDCCHs up to the first SL PDCCH; and construct a hybrid automatic repeat request (HARQ) codebook for a first number of SL transmissions scheduled by a second number of second received SL PDCCHs; wherein the HARQ codebook is sent from the UE to the base station, the first number of SL transmissions includes at least one SL transmission, the second received SL PDCCH includes the first received SL PDCCH, and the first received SL PDCCH includes the first SL PDCCH. Attached Figure Description

[0009] The exemplary viewpoint of this case can be better understood by referring to the accompanying drawings. Note that the various features in the drawings are not drawn to scale, and their dimensions may be increased or decreased arbitrarily for clarity of discussion.

[0010] Figure 1 The illustration shows a Mode-1 transmission system according to an exemplary embodiment of the present invention.

[0011] Figure 2 The diagram illustrates the relationship between K0, K1, PDCCH, and PDSCH according to an exemplary embodiment of the present invention.

[0012] Figure 3 The illustration shows multiple SL TBs for SL HARQ-ACK feedback in a PUCCH according to an exemplary embodiment of the present invention.

[0013] Figure 4 The illustration shows a flowchart of the HARQ codebook construction process according to an exemplary embodiment of the present invention.

[0014] Figure 5 The illustration shows a shared PSFCH for NACK-only feedback in SL multicast according to an exemplary embodiment of the present invention.

[0015] Figure 6 The illustration shows two PSFCHs for NACK-only feedback in SL multicast according to an exemplary embodiment of the present invention.

[0016] Figure 7 A block diagram of a node for wireless communication according to various aspects of the present invention is shown. Detailed Implementation

[0017] The following description contains specific information relating to exemplary embodiments of the invention. The accompanying drawings and detailed descriptions are for illustrative purposes only. However, the invention is not limited to these exemplary embodiments. Other variations and implementations of the invention will be apparent to those skilled in the art. Unless otherwise stated, similar or corresponding components in the figures may be indicated by similar or corresponding reference numerals. Furthermore, the drawings and illustrations in this invention are generally not drawn to scale and are not intended to correspond to actual relative dimensions.

[0018] The following description contains specific information relating to exemplary embodiments of the invention. The accompanying drawings and detailed descriptions are for illustrative purposes only. However, the invention is not limited to these exemplary embodiments. Other variations and implementations of the invention will be apparent to those skilled in the art. Unless otherwise stated, similar or corresponding components in the figures may be indicated by similar or corresponding reference numerals. Furthermore, the drawings and illustrations in this invention are generally not drawn to scale and are not intended to correspond to actual relative dimensions.

[0019] For consistency and ease of understanding, similar features are identified by numbers in the example figures (although not shown in some examples). However, features in different embodiments may differ in other respects, and therefore should not be narrowly limited to what is shown in the figures.

[0020] The designations “one embodiment,” “an embodiment,” “an example embodiment,” “various embodiments,” “some embodiments,” “embodiments of the invention,” etc., may indicate that the described embodiment of the invention may include a specific feature, structure, or characteristic, but not every possible embodiment of the invention must include that specific feature, structure, or characteristic. Furthermore, the repeated use of “in one embodiment,” “in an example embodiment,” or “an embodiment” does not necessarily refer to the same embodiment, although this is possible. Moreover, any use of terms such as “embodiment” alongside “the invention” is not intended to imply that all embodiments of the invention must include the stated specific feature, structure, or characteristic, but should be understood as meaning that “at least some embodiments of the invention” include the stated specific feature, structure, or characteristic. The term “coupled” is defined as a connection, whether direct or indirect through intermediate components, and is not necessarily limited to physical connections. The term “comprising” in use means “including but not limited to”; it specifically refers to an open inclusion or membership in the said combination, group, series, and equivalents.

[0021] The term "and / or" in this document describes the relationship between related objects only, indicating that there are three possible relationships. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, and B exists alone. "A and / or B and / or C" can mean that at least one of A, B, and C exists. Additionally, the character " / " used in this document generally indicates an "or" relationship between the preceding and following related objects.

[0022] Furthermore, for the purpose of non-restrictive interpretation, specific details, such as functional entities, technologies, protocols, standards, etc., are described to provide an understanding of the technologies described. In other examples, detailed descriptions of well-known methods, technologies, systems, architectures, etc., are omitted to avoid obscuring the description with unnecessary details.

[0023] Those skilled in the art will readily recognize that any NW function or algorithm described herein can be implemented by hardware, software, or a combination of software and hardware. The described functions may correspond to modules that can be software, hardware, firmware, or any combination thereof. Software implementations may include calculator-executable instructions stored on a calculator-readable medium such as memory or other types of storage devices. For example, one or more microprocessors or general-purpose calculators with communication processing capabilities may be programmed with corresponding executable instructions to execute the described NW functions(one or more) or algorithms(one or more). The microprocessor or general-purpose calculator may be formed from an application-specific integrated circuit (ASIC), a programmable logic array, and / or using one or more digital signal processors (DSPs). Although some of the exemplary embodiments described in this specification refer to software installed and executed on calculator hardware, alternative exemplary embodiments implemented in firmware or hardware, or a combination of hardware and software, are also within the scope of this invention.

[0024] Calculator-readable media include, but are not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, optical disc read-only memory (CD-ROM), magnetic cassette, magnetic tape, disk storage, or any other equivalent medium capable of storing calculator-readable instructions.

[0025] A radio communication NW architecture (e.g., a Long Term Evolution (LTE) system, an LTE-Advanced (LTE-A) system, or an LTE-Advanced Pro (LTE-Pro) system) typically includes at least one base station (BS), at least one user equipment (UE), and one or more optional NW components providing connectivity to the NW. The UE communicates with the NW (e.g., a Core NW (CN), an Evolved Packet Core (EPC) NW, an Evolved Universal Terrestrial Radio Access NW (E-UTRAN), a Next Generation Core (NGC), or the Internet) via a radio access NW (RAN) established by the BS.

[0026] It should be noted that, in this invention, the UE may include, but is not limited to, a mobile station, mobile terminal or device, or a user communication radio terminal. For example, the UE may be a portable wireless device, including but not limited to a mobile phone, tablet computer, wearable device, sensor, or personal digital assistant (PDA) with wireless communication capabilities. The UE is configured to receive and transmit signals to one or more cells in the RAN via an air interface.

[0027] A BS may include, but is not limited to, Node Bs (NBs) in Universal Mobile Telecommunications System (UMTS), Evolved Node Bs (eNBs) in LTE-A, Radio Network Controllers (RNCs) in UMTS, Base Station Controllers (BSCs) in Global System for Mobile Communications (GSM) / GSMEDGE Radio Access Networks (GERAN), Next-Generation eNBs (ng-eNBs) in E-UTRA BSs connected to 5GC, Next-Generation Node Bs (gNBs) in 5G Access Networks (5G-AN), and any other devices capable of controlling wireless communications and managing intra-cell radio resources. A BS can serve one or more UEs via a radio interface connected to the NW.

[0028] The BS can be configured to provide communication services based on at least one of the following radio access technologies (RATs): WiMAX, GSM (commonly referred to as 2G), GERAN, General Packet Radio Service (GPRS), UMTS based on Basic Wideband Code Division Multiple Access (W-CDMA) (commonly referred to as 3G), High-Speed ​​Packet Access (HSPA), LTE, LTE-A, enhanced LTE (eLTE), NR (commonly referred to as 5G), and LTE-A Pro. However, the scope of this invention should not be limited to the above-mentioned protocols.

[0029] A BS can be operated to provide radio coverage to a specific geographic area using multiple cells included in the RAN. The BS can support cell operation. Each cell can be operated to provide service to at least one UE within its radio coverage area. More specifically, each cell (often referred to as a serving cell) can provide services to serve one or more UEs within its radio coverage area. For example, each cell schedules downlink (DL) and optional UL resources to at least one UE within its radio coverage area for DL ​​and optional uplink (UL) packet transmissions. A BS can communicate with one or more UEs in a radio communication system through multiple cells. Cells can allocate sidelink (SL) resources to support Pro-Se services. Each cell may have coverage areas overlapping with other cells. In the case of multiple RAT dual connectivity (MR-DC), the primary cell of a Master Cell Group (MCG) or Secondary Cell Group (SCG) can be referred to as a Special Cell (SpCell). A Primary Cell (PCell) can refer to the SpCell of an MCG. A PSCell can refer to the SpCell of an SCG. An MCG refers to a group of serving cells associated with a Master Node (MN), including SpCells and one or more optional Secondary Cells (SCells). An SCG refers to a group of serving cells associated with a Secondary Node (SN), including SpCells and one or more optional SCells.

[0030] As mentioned above, the NR frame structure is designed to support flexible configuration to accommodate various next-generation (e.g., 5G) communication requirements, such as eMBB, mMTC, and URLLC, while achieving high reliability, high data rates, and low latency. Orthogonal Frequency Division Multiplexing (OFDM) technology, agreed upon in the 3rd Generation Partnership Project (3GPP), can be used as the baseline for the NR waveform. Scalable OFDM parameters, such as adaptive subcarrier spacing, channel bandwidth, and cyclic prefix (CP), can also be used. Furthermore, NR considers two coding schemes: (1) Low-Density Parity-Check (LDPC) codes and (2) Polar codes. Coding scheme adaptation can be configured based on channel conditions and / or service applications.

[0031] Furthermore, it is considered that the transmission time interval of a single NR frame should include at least DL transmission data, a protection period, and UL transmission data, wherein the various parts of the DL transmission data, the protection period, and the UL transmission data should also be configurable, for example, based on NR-based NW dynamics. Additionally, SL resources can be provided in the NR frame to support ProSe services.

[0032] Vehicle-to-everything (V2X) operations can be implemented based on different technologies, such as Dedicated Short Range Radio (DSRC), 3GPP LTE PC5 Device-to-Device (D2D), and 3GPP New Radio (SL) interface. At a higher level, they can be categorized based on their integration with cellular networks. For example, since LTE D2D and NR V2X technologies were both developed by 3GPP, their interaction and coexistence with cellular communication on the same carrier are possible. V2X technologies developed by 3GPP are also known as Cellular V2X (C-V2X).

[0033] For C-V2X technology, V2X operations (such as SL) are supported based on the Uu interface. The Uu interface is the radio interface between the mobile terminal and the radio access network (RAN). In New Radio (NR) systems, resource allocation based on Uu interface signaling is called Mode-1 resource allocation. Here, the SL transmission resources for the transmitter (TX) user equipment (UE) are indicated by the base station (BS). Similarly, the SL reception information for the receiver (RX) UE used to monitor SL traffic can also be indicated by the BS. In NR V2X, multicast and unicast transmissions can be supported, both of which can be implemented through Mode-1 resource allocation. Furthermore, Hybrid Automatic Repeat Request (HARQ) operation is supported to improve resource efficiency compared to blind (re)transmission. The SL HARQ acknowledgment (ACK) bit is fed back to the BS to facilitate further SL retransmission scheduling when needed.

[0034] Before we get to the topic, the following descriptions and / or terms can be provided.

[0035] • Step 1 SCI: The counterpart of Uu DCI in SL is carried by a PSCCH channel, which includes scheduling information for the relevant PSCCH. The PSCCH is used for sensing purposes.

[0036] • 2-Step SCI: The Uu DCI counterpart in SL is divided into two parts. The first part of the SCI includes the scheduling information from the second part of the SCI. The first part of the SCI is used for sensing and resource selection purposes.

[0037] • SL RX UE ID: In V2X, the SL RX UE ID can be an ID configured by the NAS layer, or a Layer-1 ID / Layer-2 ID derived from the NAS-configured ID. For example, the ID configured by the NAS layer can be a ProSe (Proximity Service) UE ID. In some other embodiments, the SL RX UE ID can be generated directly in the AS layer (Layer-1 or Layer-2).

[0038] Please refer to Figure 1The illustration depicts a Mode-1 transmission system 70 according to an exemplary embodiment of the present invention. Figure 1 As shown, in NR SL resource allocation mode-1, the SL resources used by the SL transmitting UE (hereinafter referred to as "SL TX UE") are scheduled by the SL PDCCH of a related BS. Resource allocation may include resources for SL control channels (e.g., physical SL control channel, PSCCH) and / or SL data channels (e.g., physical SL shared channel, PSSCH). Transmissions may be unicast, multicast, or broadcast. For mode-1 unicast or multicast transmissions, the SL TX UE reports the SL HARQ-ACK bit to the BS (e.g., gNB) via the Uu interface to indicate whether the SL receiving UE and / or SL receiving UE group (hereinafter referred to individually or collectively as "SL RX UE" or "SL RX UE(s)") of the previously transmitted transport block (TB) was successfully / failed to receive. The BS may determine whether to retransmit the TB and provide additional resource allocation based on the SL HARQ-ACK feedback. Since the SL HARQ feedback is sent via the Uu link, the UE can use the Physical Uplink Control Channel (PUCCH) and / or the Physical Uplink Shared Channel (PUSCH) to send HARQ-ACK bits. Please refer to [link / reference]. Figure 2 , Figure 2 The diagram illustrates the relationship between K0, K1, PDCCH, and PDSCH according to an exemplary embodiment of the present invention. Figure 2 The illustration shows an embodiment of a HARQ codebook generation process (e.g., the semi-static HARQ codebook described in Section 9.1.2 and the dynamic HARQ codebook described in Section 9.1.3 of 3GPP TS 38.213 V15.6.0), where the HARQ codebook is associated with K0 (e.g., PDSCH - Time Domain Resource Allocation List) and K1 (e.g., dl - DataToUL - ACK). In one embodiment, as... Figure 2 As shown, K0 indicates the time offset between the scheduled PDCCH and the corresponding scheduled PDSCH. K1 indicates the time offset between the PDSCH and the corresponding PUCCH resource used for HARQ-ACK feedback of the PDSCH. DL transmissions associated with PUCCH resources in the same time slot can be used to construct the same HARQ codebook for HARQ-ACK feedback. This mechanism cannot be directly applied to SL HARQ-ACK feedback because the PDCCH used for SL scheduling (represented as SL PDCCH or SL DCI) may not be associated with SL transmissions via K0 or K1 as in the Uu interface.

[0039] In some embodiments, two options are supported for NR SL multicast that implements HARQ-ACK bit feedback.

[0040] Option 1 (NACK only): If the SL RX UE is unable to decode the TB carried on the PSSCH after decoding the associated PSCCH, it may send a NACK status to its corresponding SL TX UE on the SL HARQ feedback channel (e.g., the Physical SL Feedback Channel, PSFCH). Otherwise, it may not send any signal on the PSFCH.

[0041] Option 2 (ACK / NACK): If the SL RX UE successfully decodes the TB carried on the PSSCH after decoding the associated PSCCH, it can send an ACK status to its corresponding SL TX UE on the PSFCH. If it fails to decode the TB after decoding the associated PSCCH targeting the SL RX UE, it can send a NACK status on the PSFCH.

[0042] In one embodiment, for the NACK-only option, in the case of multicast, all or some of the SL RX UEs can share the same PSFCH resources for HARQ-NACK feedback. For the ACK / NACK option, in the case of multicast, each SL RX UE can use its own PSFCH for feedback. In another embodiment, for ACK / NACK-based multicast, all or some of the SL RX UEs can share one PSFCH for ACK transmission and share another PSFCH for NACK transmission.

[0043] In some embodiments, the application of HARQ-ACK feedback can be configured. If HARQ-ACK feedback is not enabled by configuration, no HARQ-ACK feedback will be sent regardless of the TB's reception status. Whether or not HARQ-ACK feedback is sent can be determined by the SL RX UE based on its distance to the corresponding SL TX UE. In this distance-based HARQ-ACK feedback mechanism, if the distance between the SL TX UE and the SL RX UE is less than or equal to the communication range requirement, the SL RX UE can send SL HARQ feedback for the associated PSCCH or PSSCH. Otherwise, the SL RX UE may not send SL HARQ feedback for the PSCCH / PSSCH. The communication range requirement can be indicated by the BS or predefined, and is not limited thereto.

[0044] Note that while the availability of some scheduling information can be assumed in the description above, it is not necessary to assume that it all comes from the BS. For example, the SL HARQ feedback option and / or distance requirement in distance-based feedback can be determined by the SL TX UE (or the leader UE in the group) based on, for example, SL channel information, and this determination is reported to the appropriate BS. Therefore, the BS may need to provide appropriate resources, such as PSFCH and / or PUCCH, for the SL TX UE (or leader UE).

[0045] This document addresses several issues regarding HARQ-ACK feedback for SL multicast resource allocation used for Uu control. Firstly, it addresses how the SL TX UE translates received SL HARQ-ACK bits into information for Uu interface feedback when, for example, no signals are received from all SL RX UEs.

[0046] Second, SL HARQ codebook construction. After receiving the SL HARQ-ACK bits from the SL RX UE, how does the SL TX UE combine and multiplex / order the received HARQ-ACK bits for, for example, Uu interface feedback on the PUCCH?

[0047] Third, DL / SL HARQ-ACK codebook multiplexing. When the SL TX UE prepares the DL HARQ-ACK bits and the merged SL HARQ-ACK bits, how should the SL TX UE multiplex these two types of bits if their corresponding UL resources overlap in the time domain? Generally, this problem can be extended to the case of multiplexing UCI bits and SL HARQ-ACK bits. Therefore, the following preferred embodiments are proposed to solve the above problem.

[0048] In some embodiments, when HARQ-ACK feedback is enabled and it may be necessary to generate SL HARQ-ACK bits for feedback, the SL TX UE may not receive HARQ-ACK feedback from the SL RX UE. For example, the channel conditions of the feedback channel may be poor, causing the HARQ-ACK feedback in the SL to be lost by the SL TX UE, or distance-based feedback may be enabled, and all SL RX UEs may be out of coverage (OOC). In this case, the SL TX UE may not have information about which alternative is the cause. In Mode-1 resource allocation, it is crucial that the SL TX UE provides appropriate information to the BS so that the BS can make appropriate scheduling decisions based on the feedback from the SL TX UE.

[0049] In a preferred embodiment of ACK / NACK-based feedback, when the SL TX UE does not detect reception of any PSFCH channel, the generation of its HARQ-ACK bits for associated SL transmissions depends on whether distance-based HARQ-ACK feedback is applied. For example, if no signal is received on the PSFCH, it can provide NACK feedback on the UL when distance-based feedback for multicast is not configured; or, when distance-based feedback for multicast is configured, it can provide ACK feedback on the UL if no signal is received on the PSFCH. In one embodiment, it should be noted that the UE does not expect different HARQ-ACK options within the group (i.e., NACK only and ACK / NACK-based) to be used for multicast.

[0050] For the construction of the SL HARQ-ACK codebook, two issues need to be considered. First, the number of HARQ-ACK bits to be included in a TB codebook, and the multiplexing of HARQ-ACK bits if the number of bits may be more than one. Second, in uplink transmission, the number of TBs of HARQ-ACK information that the SL TX UE can feedback. In one example, the HARQ-ACK information may only include SL HARQ-ACK bits. In another example, the HARQ-ACK information may include SL HARQ-ACK and DL HARQ-ACK (HARQ-ACK for DL ​​transmission) bits.

[0051] Considering the first issue in the preceding paragraphs, as shown in one embodiment, each SLRX UE in a multicast group can occupy its own PSFCH resources for SL HARQ-ACK feedback, such as ACK / NACK-based SL HARQ feedback. An SLTX UE can receive as many HARQ-ACK states as there are SL RX UEs in the multicast group. In another embodiment, a similar issue may arise with NACK-only feedback, where more than one PSFCH resource is used for HARQ-ACK feedback between SL RX UEs in the multicast group.

[0052] Please refer to Figure 3 , Figure 3 Multiple SL TBs for SL HARQ-ACK feedback in a UL time slot are illustrated according to an example implementation of this disclosure. Figure 3As shown, considering the second issue, it can be assumed that multiple SL TBs are scheduled by multiple SL DCIs for the same SL TX UE, where each SL PDCCH can be used to schedule one or more SL gearboxes. Furthermore, the target SL RX UEs of the two TBs may be the same or different. The feedback channels for each TB and / or PSFCH are determined in this way, allowing the SL HARQ-ACK information of two SL TBs to be reported via UL resources in the same UL time slot. This assumes that two PSFCHs occur simultaneously (i.e., in the same SL time slot) but in different frequency resources (e.g., different sub-channels), which may occur in unicast and / or multicast. It should be noted that the accompanying figures are for illustrative purposes only and are not intended to limit the scope. In one embodiment, Figure 3 The SL control information (SCI) includes a 2-step SCI. In another embodiment, Figure 3 The SL data includes multiple transfers of TB. Among these varieties, the operation of other parts of the SL HARQ, such as SLDCI, PSFCH, and PUCCH, which are highly relevant to the discussion in this data, remains unchanged.

[0053] Specifically, for the first problem of individual SL RX UEs using individual PSFCHs in response to ACK / NACK-based feedback in response to multicast transmissions, two solutions are proposed. In some embodiments, the first solution may be to merge HARQ-ACK bits from SL RX UEs within a group by means of the following embodiment. In one embodiment, it may include all individual ACK / NACK bits for individual SL TX UE-RX UE pairs in the HARQ codebook. That is, there is no merging. All received ACK / NACK bits corresponding to the same multicast TB are included as SLHARQ-ACK information for the SL TX UE. For the multiplexing of individual ACK / NACK bits, in one embodiment, the ACK / NACK bits corresponding to the PSFCH with a lower starting frequency domain resource index (e.g., sub-channel index) are multiplexed earlier.

[0054] In another embodiment, the second solution can aggregate the ACK / NACK bits for each SLTX UE, for example, across SL RX UE bundles. Here, for each multicast TB, only one HARQ-ACK bit is included in the SLHARQ-ACK information ultimately considered and / or used for Uu link reporting. In another embodiment, an ACK bit is generated if the feedback received from all PSFCHs is ACK; otherwise, a NACK bit is generated.

[0055] It is worth noting that, for the above solutions, whether or not to perform a merge can be configured by the BS.

[0056] Similarly, for the second question, SL HARQ-ACK information associated with multiple TBs will be merged, reused, and / or sorted for feedback using UL resources. That is, SL HARQ-ACK information is sorted at the TB resolution, and this method of sorting SL HARQ-ACK information at the TB level can follow one or a combination of the following three schemes.

[0057] In one embodiment, a first solution considering direct indication in scheduling SL DCI could be that the SL Allocation Indicator (SAI) field (e.g., in scheduling DCI via SL PDCCH) has an operation similar to the Uu interface DAI, as can be understood in 3GPP TS 38.213 V15.6.0, for example. Assume the UE can be configured to receive a first SL PDCCH from the BS, and the SL PDCCH can provide the UE (typically referred to as the SL TX UE) with scheduling information for at least one SL transmission. In this case, the SAI field can be calculated only for at least one SL transmission.

[0058] In one embodiment, the UE can obtain the value of the SAI field from the first SL PDCCH, wherein the value of the SAI field is configured to indicate the cumulative number of first received SL PDCCHs up to the first SL PDCCH. Next, in another embodiment, the UE can construct a HARQ codebook for a first number of SL transmissions scheduled by a second number of second received SL PDCCHs. In another embodiment, the HARQ codebook can be sent from the UE to the BS, the first number of SL transmissions may include at least one SL transmission, the second received SL PDCCHs may include the first received SL PDCCHs, and the first received SL PDCCHs may include the first SL PDCCH. Generally, at least one SL transmission can correspond to one TB, which is not limited here.

[0059] In one embodiment, similar operations to those of the Uu interface DAI, as understood from, for example, 3GPP TS 38.213 V15.6.0, can be applied. Specifically, received SL PDCCHs are detected within a set of PDCCH monitoring opportunities. These PDCCH monitoring opportunities may be SL PDCCH monitoring opportunities for sending PDCCHs used to schedule SL services. This set of PDCCH monitoring opportunities can be indicated or configured by the BS to report SL HARQ-ACK information via the Uu interface. Based on the indication from the BS, the set of PDCCH monitoring opportunities can be limited to a time period and can occur repeatedly. This set of PDCCH monitoring opportunities can be configured to report SL HARQ-ACK feedback in the same UL time slot.

[0060] In one embodiment, at least one SL transmission can determine a bit of the HARQ codebook. Preferably, in another embodiment, the value of the SAI field in the first SL PDCCH can determine the order of a bit in the HARQ codebook.

[0061] Furthermore, in some embodiments, the received SL PDCCH provides resource allocation information for one or more transmissions performed by the UE via SL communication. For example, the UE (i.e., SL TX UE) can transmit SL services provided by the received SL PDCCH to the corresponding SL RX UE and / or SL RX UE group. The SL RX UE and / or SL RX UE group can be covered by the same BS as the SL TX UE, or by another BS, and is not limited thereto. Specifically, in one embodiment, a bit of the HARQ codebook can indicate whether the SL RX UE and / or SL RX UE group has successfully received an ACK / NACK message for at least one SL transmission.

[0062] In some embodiments, multiple bits in the HARQ codebook are processed through bundling and / or multiplexing operations. In practice, the ordering of SL HARQ-ACK bits representing any SL UE (including SL TX UE, SL RX UE, and / or SL RX UE groups) may follow the SAI value PDCCH provided in the SL. In one embodiment, an SL HARQ-ACK bit corresponding to an SL transmission with a lower SAI value may be multiplexed earlier. In another embodiment, the SAI field may include a count SAI value used to provide an index of the SL transmission. In yet another embodiment, the SAI field may include a total value providing information about the total number of SL transmissions whose SL HARQ-ACK information should be multiplexed together for Uu feedback.

[0063] Please refer to Figure 4 , Figure 4 A flowchart of the process 30 for constructing a HARQ codebook according to an example implementation of this disclosure is shown. Figure 4 As shown, procedure 30 includes the following steps:

[0064] Step 300: Begin.

[0065] Step 302: Receive the first SL PDCCH from the BS. The first SL PDCCH provides scheduling information for at least one SL transmission.

[0066] Step 304: Obtain the value of the SAI field from the first SL PDCCH. The value of the SAI field represents the cumulative number of SLPDCCHs received from the first SL PDCCH.

[0067] Step 306: Construct a HARQ codebook for the first number of SL transmissions scheduled by the second number of second received SL PDCCHs.

[0068] Step 308: End.

[0069] As shown above, the UE (i.e., SL TX UE) can use procedure 30 to construct a HARQ codebook to send the HARQ codebook (including SL HARQ-ACK information from SL RX UE and / or the SL RX UE group) to the BS. Specific operations for steps 302 to 306 can be found in the preceding paragraphs and are omitted below for brevity.

[0070] The second approach, considering the multiplexing / ordering of SL HARQ-ACK information associated with multiple TBs, can be an indirect indication in scheduling SL DCI, and can be proposed using the following two methods. In the first method, the ordering of TB-level HARQ-ACK information can follow the order of monitoring timings used for the corresponding SL PDCCH transmissions. In one embodiment, HARQ-ACK information of SL transmissions corresponding to earlier monitoring timings can be multiplexed earlier. Note that "monitoring timing" can follow the same definition as detailed, for example, in 3GPP TS 38.213 V15.6.0. The monitoring occasion itself may not distinguish between Uu DCI and SLDCI. In other words, monitoring timings can be used for both Uu DCI and SL DCI. The search space set itself can distinguish the DCI format used for Uu scheduling as well as the format used for SL scheduling. A monitoring occasion may include multiple search space sets. Comparisons between monitoring periods can be performed between monitoring periods of the same type (i.e., Uu or SL) DCI scheduling. In another embodiment, for two search space sets at the same monitoring time, the SL HARQ-ACK information corresponding to the set with the lower search space index is reused earlier.

[0071] In the second approach, the ordering of TB-level SL HARQ-ACK information can follow the resource index allocated for PSFCH transmission. For example, SL HARQ-ACK information associated with PSFCHs with smaller frequency domain start subchannels is multiplexed earlier. In one embodiment, more than one PSFCH can be associated with a multicast transmission. In this case, specific PSFCH resources can be used. A specific PSFCH can be associated with the PSFCH having the lowest start subchannel index or the lowest SL RX UE layer-1 ID.

[0072] Considering DL and / or SL HARQ multiplexing, in some embodiments, the PUCCH resources used for DL ​​HARQ-ACK feedback and for SL HARQ-ACK feedback can be independently indicated by the BS. When overlapping symbols exist in the PUCCH resources, codebook concatenation can be performed. If codebook concatenation is performed, it is necessary to determine which PUCCH resource is used for the concatenated SL HARQ-ACK feedback, while ignoring the other PUCCH resource. Furthermore, the multiplexing of the general UCI and SL HARQ-ACK will be further explained below.

[0073] For SR and SL PUCCH format-0 / 1 reports used to indicate affirmative or negative SR, and for up to two SL HARQ bits in PUCCH format-0 or PUCCH format-1 resources, the following four methods can be proposed when SR resources and SLPUCCH format-0 / 1 resources conflict, for example, when symbols overlap in the two resources.

[0074] In the first method, in one embodiment, for a PUCCH resource with a positive SR overlapping with a PUCCH format 0 resource of up to two SL HARQ bits, the PUCCH format 0 resource has a cyclic shift based on a predefined table that can be requested for transmission. Positive SR information can be carried in PUCCH format 0 by means of the cyclic shift. The predefined table can be the same as, for example, the DL HARQ bit transmission defined in TS38.213V15.6.0, and is not limited thereto.

[0075] In the second method, in one embodiment, for a negative SR whose PUCCH resource overlaps with a PUCCH format 0 resource of up to two SL HARQ bits, a PUCCH format 0 resource with a cyclic shift based on a predefined table can be requested for transmission. The predefined table can be the same as, for example, the DL HARQ bit transmission defined in TS 38.213 V15.6.0, and is not limited thereto. It is worth noting that the predefined table differs from the predefined table used for affirmative SR and SL PUCCH format 0.

[0076] In a third approach, in one embodiment, for positive or negative SRs in PUCCCH format 0 that overlap with PUCCH format 1 resources of up to two SL HARQ bits, SL HARQ bits -1 can be transmitted using the PUCCH format. SR information may be discarded.

[0077] In the fourth method, in one embodiment, for a positive SR in PUCCH format-1 that overlaps with the SL HARQ bits in PUCCH format-1, the SR PUCCH format-1 resource can be used for SL HARQ bit transmission. In another embodiment, for a negative SR in PUCCH format-1 that overlaps with the SL HARQ bits in PUCCH format-1, the SL HARQ PUCCH format-1 resource can be used for SL HARQ bit transmission. That is, SR information is carried through the on / off keying of the SR PUCCH format-1 resource.

[0078] For the overlap of DL HARQ bits on a PUCCH format 0 or PUCCH format 1 resource with SL HARQ bits on another PUCCH format 0 or PUCCH format 1 resource, two solutions can be proposed.

[0079] In some embodiments, the first solution is to select one of the DL and SL HARQ PUCCH resources for transmission. The other PUCCH resource is discarded from the transmission. The merged HARQ-ACK bits from DL and SL are transmitted on the selected PUCCH resource. The selection of which PUCCH resource to transmit on can be based on one or a combination of the following three methods.

[0080] In the first approach, in one embodiment, the PUCCH resource associated with a fixed interface (e.g., an SL interface or a Uu interface) can be used for transmission. The fixed interface can be pre-specified / pre-configured / configured.

[0081] In the second method, in one embodiment, PUCCH resources associated with a specific format are preferentially discarded. For example, when two PUCCH resources correspond to different PUCCH formats, PUCCH format 1 can be selected for discarding.

[0082] In one embodiment, the third method may determine which resource to discard based on a priority determined through various means. Note that in one embodiment, the resource with the lower / lowest priority may be discarded.

[0083] In one embodiment, the first approach is that the DLHARQ-ACK bits corresponding to high-priority DL services (e.g., URLLC services) can be distinguished by the corresponding scheduling DCI. Priorities can be binary, i.e., low priority and high priority. If such different priorities can be associated with different DL HARQ-ACK bits, then the highest priority among them can be assumed.

[0084] In one embodiment, the second approach is that the priority of the SL HARQ-ACK bits can be determined based on the explicit priority field in the corresponding SCI. If such different priorities can be associated with different SL HARQ-ACK bits, then the highest priority among them can be assumed.

[0085] In one embodiment, a third approach is to send the DL HARQ-ACK codebook on its (for DL) PUCCH resource for the DL HARQ-ACK information corresponding to the high-priority indication via DCI. Therefore, the DL HARQ-ACK bits can be discarded.

[0086] In one embodiment, the fourth approach is that a priority threshold may exist for the SCI priority field. For DL ​​HARQ-ACK information corresponding to a low-priority indication via DCI, if the SCI priority field associated with the SL HARQ-ACK bit indicates a low priority, the DL HARQ-ACK codebook can be sent on its (for DL) PUCCH resource exceeding the priority threshold. Therefore, the SL HARQ-ACK bit can be discarded. In another embodiment, for DL ​​HARQ-ACK information corresponding to a low-priority indication via DCI, if the SCI priority field associated with the SL HARQ-ACK bit indicates a priority higher than or equal to the priority threshold, the SL HARQ-ACK bit can be discarded.

[0087] The second approach, in some embodiments, involves determining the merging of HARQ-ACK bits based on two methods. In one embodiment, the first method is that if the PUCCH resource cannot accommodate all DL and SL HARQ-ACK bits, then HARQ-ACK bits from one interface (DL or SL) can be selected for discarding. This selection can be based on the first method of selecting PUCCH resources described above. In another embodiment, the second method is that if the size of the connected payload can fit within the PUCCH format 0 / 1 resource, then all DL / SL HARQ-ACK bits can be merged for transmission on the selected PUCCH resource.

[0088] If the long format PUCCH used for UCI conflicts with the short format PUCCH used for SL HARQ-ACK, or if the short format PUCCH used for UCI conflicts with the long format PUCCH used for SL HARQ-ACK, the long format PUCCH can be selected for multiplexing UCI and SL HARQ-ACK. In one embodiment, if PUCCH format 2 / 3 / 4 used for UCI conflicts with PUCCH format 0 / 1 used for SL HARQ, PUCCH format 2 / 3 / 4 can be selected to transmit the multiplexed UCI and SL HARQ-ACK bits.

[0089] In another embodiment, for cases where PUCCH resources overlap between positive or negative SR, DL HARQ bits and SL HARQ bits, these solutions can be applied first to merge these HARQ bits. Then, SR and HARQ-ACK bit multiplexing can be applied. Preferably, the SR and HARQ-ACK bit multiplexing method can be found in, for example, TS 38.213 V15.6.0 or other similar solutions described in this disclosure.

[0090] In some embodiments, if the PUCCH resources determined based on the above solution overlap with the PUSCH, the payload generated based on the above-proposed solution, which may include UCI and SL HARQ-ACK bits, can be multiplexed and propagated on the PUSCH.

[0091] In some embodiments, note that the SL TX UE may not be able to transmit simultaneously on both UL and SL. Therefore, simultaneous transmission of {PUCCH and / or PUSCH} and {PSCCH or PSSCH or PSFCH} may not be permitted. Consequently, transmissions from one interface may take precedence over those from the other. The principles provided herein or below can be applied to selecting a channel for transmission.

[0092] As mentioned earlier, providing SL HARQ-ACK bit feedback via UL resources requires additional processing beyond normal Uu interface operations. Therefore, other related solutions are proposed to address the following issues.

[0093] In some embodiments, when SL HARQ-ACK feedback is enabled, the SL TX UE may not receive HARQ-ACK feedback from the SL RX UE. For example, this could be due to poor channel conditions on the feedback channel, causing the SL TX UE to lose HARQ-ACK feedback from the SL, or distance-based feedback being enabled, and all SL RX UEs potentially being outside the coverage area (OOC) of the SL TX UE. The SL TX UE has no information about which reason has occurred. In Mode 1 resource allocation, the key is for the SL TX UE to provide appropriate information to the BS so that the BS can make appropriate scheduling decisions based on the feedback from the SL TX UE. Unicast may also encounter this DTX problem if distance-based HARQ-ACK operation is applied.

[0094] In one embodiment, for ACK / NACK-based feedback, when the SL TX UE does not detect any PSFCH channel reception, the generation of its HARQ-ACK bits for associated SL transmissions depends on whether distance-based HARQ-ACK feedback is applied, as detailed below. This is because when distance-based feedback is not assumed, the BS should be aware of the possibility that the SL RX UE has not received the SL PSCCH / PSSCH and should therefore consider retransmission. In one implementation, if no signal is received on the PSFCH, a NACK indication is generated when no distance-based feedback is configured for multicast and / or unicast. In another implementation, when distance-based feedback is configured for multicast and / or unicast, an ACK indication is generated if no signal is received on the PSFCH. It should be noted, of course, that the UE does not expect different HARQ-ACK options within a multicast group (i.e., NACK only and ACK / NACK-based).

[0095] In some embodiments, to inform the gNB of the full SL ACK / NACK state, an additional feedback state, DTX, is introduced to notify the SL TX UE that no signal has been received. In one embodiment for NACK-only feedback, DTX can be transmitted on the UL if no signal is received on the PSFCH, even when distance-based feedback for multicast and / or unicast is not configured. When distance-based feedback for multicast and / or unicast is configured, ACK can be sent on the UL if no signal is received on the PSFCH. In one embodiment for ACK / NACK-based feedback, DTX can be transmitted on the UL if no signal is received on the PSFCH, when distance-based feedback for multicast and / or unicast is not configured. When distance-based feedback for multicast and / or unicast is configured, NACK can be sent on the UL if no signal is received on the PSFCH.

[0096] In some embodiments, for NACK-only feedback in multicast scenarios, more than one feedback channel (i.e., PSFCH) can be shared among SL RX UEs within a group. Therefore, the SL RX UEs within a group can be further divided into subgroups, each subgroup mapped to one or more PSFCHs. Please refer to [reference needed]. Figure 5 and Figure 6 ,in Figure 5 The illustration shows a shared PSFCH for NACK-only feedback in SL multicast according to an exemplary embodiment of this disclosure, and Figure 6 The illustration shows two PSFCHs in SL multicast with only NACK feedback, implemented according to the example in this disclosure. For example... Figure 5 and Figure 6 As shown, one or two PSFCH resources can be used separately within an SL multicast group. Figure 6 In this embodiment, the SL RX UE is divided into two subgroups, each of which can share one PSFCH for NACK-only feedback. It should be noted that the following explanation uses two PSFCHs for the two subgroups as examples, but is not limited to the scope of this embodiment. In other words, for those skilled in the art, it is straightforward to adjust the number of subgroups to other values ​​and apply the same principles as described above. Preferably, the formation of subgroups can follow different methods. In one embodiment, it is instructed by the BS via higher-layer signaling. In another embodiment, subgroup formation is performed by the SL TX UE, and the result of subgroup formation may or may not be fed back to the BS. If subgroup information is notified, the BS can subsequently configure relevant resources, including PSFCH resources. If the BS does not receive subgroup information, the SL TX UE can allocate the allocated number of PSFCHs (by the BS) to the subgroups itself. In another embodiment, the allocation can be based on pre-specified rules.

[0097] In some embodiments, when more than one PSFCH can be used for NACK-only feedback as described above, the SL TX UE can determine the NACK state for each PSFCH channel (i.e., a subgroup of each SL RX UE) for each PSFCH channel received. When no NACK is received from a PSFCH, the SL TX UE can determine the ACK state for the corresponding PSFCH channel. The SL HARQ-ACK report via the Uu interface can be further determined based on the number of PSFCHs and the number of HARQ-ACK bits in the multicast group.

[0098] In one embodiment, if a single PSFCH is shared by all SL RX UEs, an ACK indication is generated if no signal is received on the PSFCH; or, a NACK indication is generated if a NACK indication is received on the PSFCH.

[0099] In one embodiment, more than one PSFCH can be shared by all SL RX UEs. If the multicast group sends only one merged HARQ-ACK bit on the UL, the SL TX UE can send an ACK indication on the UL if no signal is received on any PSFCH, and send a NACK indication on the UL if a NACK is received from any PSFCH. On the other hand, if a merged HARQ-ACK bit is generated for each PSFCH for UL feedback, the SL TX UE can generate an ACK indication if no signal is received on the corresponding PSFCH, and generate a NACK indication if a NACK indication is received on the corresponding PSFCH. The generated SL HARQ-ACK bits corresponding to each PSFCH (i.e., the ACK and NACK indications above) can be aggregated and ordered for UL feedback. Specifically, the ordering can be based on the PSFCH resource index (e.g., the starting subchannel index, the starting PRB index) and / or the subgroup ID.

[0100] Note that in one embodiment, a combined HARQ-ACK bit can be determined based on the ACK ratio. For example, if the SLTX UE determines that the feedback received in the NACK state across all possible receptions is greater than a given threshold, the SLTX UE can indicate "NACK" to the BS for this allocation of the PSFCH; otherwise, the SLTX UE can indicate "ACK" to the BS. In another embodiment, the threshold can be pre-configured / predefined by the gNB or signaled. It is worth noting that the determination of the ACK / NACK state can follow the operations and / or mechanisms provided in other embodiments, which will not be repeated below for the sake of brevity.

[0101] Similarly, there are two dimensions to consider when constructing the SL HARQ-ACK codebook. First, how many HARQ-ACK bits might be needed in a TB codebook, and how to multiplex them if there are more than one? Second, how many TBs of HARQ-ACK information can the SL TX UE send back during uplink transmission?

[0102] For the first question, it can be similar to being based on the NACK-only option. Figure 6The icon is not explicitly defined, but it can be extended to ACK / NACK-based feedback scenarios. For ACK / NACK-based SL HARQ feedback, each SL RX UE in the multicast group can occupy its own PSFCH resources for SL HARQ-ACK feedback, and the SL TX UE can receive as many HARQ-ACK states as the number of SL RX UEs in the multicast group.

[0103] Regarding the second question, assuming that more than one SL PDCCH can schedule more than one SLTX UE for the same SL TX UE, such as... Figure 3 As shown. TBs may be the same or different. The feedback channel for each TB (i.e., PSFCH) is determined such that the SL HARQ-ACK information for both SL TBs will be reported through the UL resource in the same UL time slot. For example... Figure 3 As shown, assume two PSFCH events occur simultaneously (e.g., in the same SL slot) but in different frequency resources (e.g., in different sub-channels). This situation can occur in unicast and / or multicast.

[0104] Returning to the first question above, in response to multicast transmission, more than one PSFCH resource can be used for HARQ-ACK information, and HARQ-ACK information can correspond to NACK-only feedback or ACK / NACK-based feedback.

[0105] Specifically, the merging of HARQ-ACK bits from SL RX UEs within the same group can include the following three schemes.

[0106] In one embodiment, a first solution is that all individual HARQ-ACK bits for each SL TX UE-RX UE pair can be included in the HARQ codebook. That is, there is no merging. All received HARQ-ACK bits corresponding to the same multicast TB are included by the SL TX UE as SL HARQ-ACK information. For the multiplexing of individual ACK / NACK bits, it can be based on the PSFCH resource index used to receive the corresponding ACK / NACK bits from the SL RX UE, or based on the SL RX UEId, for example, a Layer 1 ID. In another embodiment, the ACK / NACK bits corresponding to the PSFCH with the lowest starting frequency domain resource index (e.g., sub-channel index) can be multiplexed first or last.

[0107] In one embodiment, a second solution could be to aggregate HARQ-ACK bits by bundling, for example, across SL RX UEs or across PSFCHs. In this case, only one HARQ-ACK bit is included in the SL HARQ-ACK information for each multicast TB. In another embodiment, an ACK bit is generated if the feedback received from all PSFCHs is ACK; otherwise, a NACK bit is generated.

[0108] In one embodiment, a third solution could be the aggregation of HARQ-ACK bits from SL RX UEs sharing the same PSFCH, for example, by bundling receive bits across SL RX UEs. In this case, ACK / NACK bits are generated for each associated PSFCH resource. Preferably, it can be noted that whether merging is performed in any of the above solutions can be configured by the BS, and is not limited thereto.

[0109] Regarding the second issue mentioned above, HARQ-ACK information associated with multiple TBs will be reused and / or ordered for feedback using UL resources. In some embodiments, it can focus on the ordering of merged SL HARQ-ACK bits within the TB level. That is, ordering is performed among HARQ-ACK information at the TB resolution. The ordering of HARQ-ACK information within a TB can follow the scheme mentioned in the first part above. Furthermore, the scheme for ordering TB-level HARQ-ACK information can adopt one or a combination of the following seven schemes.

[0110] In one embodiment, the first solution may be based on direct indications in the scheduling SL DCI. In one embodiment, there is a SAI field (e.g., in the scheduling SL PDCCH) whose operation may be similar to the Uu interface DAI, as detailed in 3GPPTS 38.213 V15.6.0, for example. The SAI field may only count SL transmissions, i.e., the cumulative number of received SL PDCCHs. The ordering of SL HARQ-ACK bits may follow the SAI value provided in the scheduling SL PDCCH. For example, in another embodiment, SL transmissions corresponding to lower SAI values ​​may be multiplexed earlier. The SAI field may include a counter SAI value used to provide an index of the scheduled SL transmissions. The SAI field may include a total SAI value to provide information about the total number of SL transmissions whose HARQ-ACK information should be multiplexed together for Uu feedback, up to the SL scheduling command for the associated SL TX UE.

[0111] In one embodiment, similar operations to those of the Uu interface DAI, as understood from, for example, 3GPP TS 38.213 V15.6.0, can be applied. Specifically, received SL PDCCH can be detected within a set of PDCCH monitoring opportunities. PDCCH monitoring opportunities can be / include SL PDCCH monitoring opportunities, where a PDCCH for scheduling SL services is transmitted. This set of PDCCH monitoring opportunities can be indicated or configured by the BS to report SL HARQ-ACK information via the Uu interface. Based on the indication from the BS, the set of PDCCH monitoring opportunities can be limited to a time period and can occur repeatedly. This set of PDCCH monitoring opportunities can be configured to report SL HARQ-ACK feedback in the same UL time slot.

[0112] The second approach, in one embodiment, can be an indirect indication in scheduling SL DCI, and can include the following four methods. The first method can be based on the SL DCI monitoring timing order. In one embodiment, the ordering of TB-level HARQ-ACK information can follow the order of monitoring timings used for SL DCI transmissions. In one embodiment, HARQ-ACK information for SL transmissions corresponding to earlier monitoring timings can be reused earlier. Note that "monitoring timing" can follow the same definition as detailed, for example, in 3GPP TS38.213 V15.6.0. The monitoring occasion itself may not distinguish between Uu DCI and SL DCI. That is, monitoring timings can be used for both Uu DCI and SL DCI. The search space set itself can distinguish the DCI formats used for Uu scheduling and SL scheduling. A monitoring occasion may include multiple search space sets. Comparisons between monitoring occasions can be made between monitoring occasions that may be scheduled by the same type of DCI (e.g., Uu or SL). In another embodiment, for two search space sets within the same monitoring occasion, the HARQ-ACK information corresponding to the set with the lower search space index is reused earlier.

[0113] The second approach can be based on SCI resource ordering. Specifically, the ordering of TB-level HARQ-ACK information can follow the resource index allocated for PSCCH transmission. In one embodiment, HARQ-ACK information associated with an earlier-transmitted PSCCH is multiplexed earlier. In another embodiment, HARQ-ACK information associated with a PSCCH with a smaller starting subchannel / PRB (i.e., frequency domain resource index) is multiplexed even earlier.

[0114] The third method can be based on PSSCH resource ordering. Specifically, the ordering of TB-level HARQ-ACK information can follow the resource index allocated for PSSCH transmission. In one embodiment, HARQ-ACK information associated with an earlier transmitted PSSCH is multiplexed earlier. The transmission time can be related to the start symbol in the time slot used for PSCCH transmission. The transmission time can be related to the time slot number used for PSCCH transmission. In another embodiment, HARQ-ACK information associated with PSSCHs with a smaller start subchannel / PRB in the frequency domain is multiplexed earlier.

[0115] The fourth method can be based on the PSFCH frequency resource index. Specifically, the ordering of TB-level HARQ-ACK information can follow the resource index allocated for PSFCH transmission. In one embodiment, HARQ-ACK information associated with a PSFCH with a smaller starting subchannel in the frequency domain is multiplexed earlier. In another embodiment, multiple PSFCHs may be associated with multicast transmissions. Therefore, a specific PSFCH resource can be used. A specific PSFCH can be associated with the PSFCH having the lowest starting subchannel index or the lowest SLRX UE ID, for example, layer-1 ID.

[0116] In one embodiment, the third solution may involve performing a bundling operation on HARQ-ACK information. In one embodiment, bundling is performed between TBs. For example, when applying a bundling operation to two TBs, an AND operation can be applied, thereby reducing the payload size of the merged HARQ-ACK information by half. In another embodiment, a pair of TBs with HARQ-ACK states, such as {ACK, NACK}, can result in a NACK state after TB-style bundling. Note that applying a bundling operation may present other issues. In one embodiment, the two TBs may correspond to different timings (TDM-ed) for applying the bundling operation. In another embodiment, the two TBs may need to be spatially multiplexed TBs for applying the bundling operation.

[0117] In one embodiment, carrier aggregation (CA) is performed / configured in the Uu interface, and the fourth solution can be applied to HARQ-ACK information multiplexing / ordering. In one embodiment, in addition to the method described above for ordering HARQ-ACK information using Uu resource differentiation, the fourth solution also involves using a CC index to determine the ordering of TB-level HARQ-ACK information. In this case, the CC index applies to a given time slot / mini-time slot. Within the same time slot / mini-time slot, the above solution still applies. In another example, HARQ-ACK information corresponding to a lower-indexed CC is multiplexed earlier.

[0118] In one embodiment, carrier aggregation (CA) is performed / configured in the SL interface, and the fifth solution can be applied to HARQ-ACK information multiplexing / ordering. In one embodiment, in addition to the method described above for ordering HARQ-ACK information using SL resource differentiation, the fifth solution also involves using a CC index to determine the ordering of TB-level HARQ-ACK information. In this case, the CC index applies to a given time slot / mini-time slot. Within the same time slot / mini-time slot, the above solution still applies. In another embodiment, HARQ-ACK information corresponding to a lower-indexed CC is multiplexed earlier.

[0119] The sixth solution, in one embodiment, for multi-TRP scenarios where SL scheduling information can be received from different Transmit-Receive Points (TRPs) within the same time slot / hourly slot, can be configured in the control resource set (CORESET) to distinguish scheduling from different TRPs. This can include a high-level index used to determine the TB-level HARQ-ACK information ordering of the above-described Uu resource-based differentiation solution. In another embodiment, HARQ-ACK information corresponding to the same high-level index is first multiplexed based on the above scheme, and then further concatenated based on the high-level index.

[0120] The seventh approach, in one embodiment, includes DL / UL operations on the Uu interface that can include DL / UL operations with the primary node (or primary cell group) and DL / UL operations with the secondary node (or secondary battery pack).

[0121] DL / SL HARQ-ACK bit multiplexing is addressed below. Two advanced solutions can be applied to multiplex HARQ-ACK bits from DL and SL transmissions. The first solution is codebook concatenation. In one embodiment, the HARQ-ACK codebooks are constructed independently for DL ​​and SL, and therefore, these two codebooks are subsequently concatenated. The second solution is a TDM-ed PUCCH in a single UL slot. In one embodiment, a separate PUCCH resource is used for SL and DL HARQ-ACK feedback. The individual PUCCH resources can be in the same UL slot, but overlapping symbols are not allowed between the individual PUCCH resources.

[0122] For the concatenation of DL / SL HARQ-ACK codebooks, in some embodiments, the PUCCH resources used for DL ​​HARQ-ACK feedback and for SL HARQ-ACK feedback can be independently indicated by the BS. Codebook concatenation can be performed when overlapping symbols exist in the PUCCH resources. If codebook concatenation is performed, it may be necessary to determine which PUCCH resource is used for concatenating HARQ-ACK information feedback while ignoring other PUCCH resources. In one embodiment, following current Uu interface procedures, such as detailed in TS 38.213V15.6.0, SR and CSI information can be multiplexed with DL HARQ-ACK bits. Therefore, the general case of UCI and SL HARQ-ACK multiplexing can be further presented below.

[0123] For UCI and SL HARQ-ACK multiplexing, four solutions are proposed below. In one embodiment, the first solution is that each SL TB can construct up to one HARQ-ACK bit. Short PUCCH formats (e.g., format 0 and format 1) can be indicated by the scheduling SL DCI for SL HARQ-ACK feedback in two ways. The first method can be applied to unicast SL communication. If HARQ-ACK information merging is performed as described above, the first method can be applied to multicast ACK / NACK-based feedback. If there is HARQ-ACK information merging per multicast group, or when there is more than one PSFCH per multicast group, the second method can be applied to multicast NACK-only feedback.

[0124] In one embodiment, the second solution is that the number of HARQ-ACK bits per SL TB can correspond to the number of SL RX UEs in the multicast group. This second approach is applicable to multicast ACK / NACK-based feedback. The second solution can be applied when using a long PUCCH format (i.e., format-2 / 3 / 4).

[0125] In one embodiment, Uu UCI can be one of (1) CSI, (2) CSI and SR, (3) CSI and DL HARQ, and (4) CSI, DL HARQ, and SR. In a third embodiment, Uu UCI can be reported in combination with the SL HARQ-ACK codebook. In one embodiment, the SL HARQ-ACK can first be concatenated with the DL HARQ-ACK codebook to form HARQ-ACK bits. Subsequently, the multiplexing between SR, the concatenated HARQ-ACK bits, and CSI can follow the Uu interface, as detailed, for example, in TS 38.213 V15.6.0.

[0126] In one embodiment used for multiplexing purposes, a third solution is that the SR associated with the SL can be indistinguishable from the DL SR. Therefore, independent SL SR transmissions in the Uu interface can follow either PUCCH format 0 or PUCCH format 1.

[0127] In one embodiment, a fourth solution is to reuse the UCI and SL HARQ-ACK if the UCI does not correspond to a high-priority transmission. For example, the UCI may include DL HARQ-ACK information corresponding to a high-priority transmission (e.g., a URLLC transmission). The SL HARQ-ACK can be discarded when instructing the SL HARQ-ACK to use UL resources with overlapping symbols as those used for high-priority UCI transmissions.

[0128] On the other hand, if the UCI does not correspond to a high-priority transmission, the SL HARQ-ACK and UCI can be multiplexed based on the following scheme. The DL HARQ-ACK bit corresponding to a high-priority DL service (e.g., URLLC service) can be distinguished by the corresponding scheduling DCI. In one embodiment, a DCI field for explicit indication or a (pre)specified / (pre)configured RNTI can be used to scramble the scheduling DCI. Priorities can be binary, i.e., low priority and high priority.

[0129] Considering the selection of PUCCH resources for multiplexing DL and SL HARQ-ACK transmissions, the following three solutions can be proposed.

[0130] In some embodiments, the first solution can be SR and SL PUCCH format -0 / 1. There, positive or negative SR can be considered, as well as up to two SL HARQ-ACK bits in PUCCH format 0 or PUCCH format 1 resources.

[0131] In one embodiment, the PUCCH resource for a positive SR can overlap with a PUCCH format 0 resource of up to two SL HARQ bits, allowing a PUCCH format 0 resource with a predefined table-based cyclic shift to be applied for propagation. Positive SR information can be carried in PUCCH format-0 via cyclic shift selection. The predefined table can be the same as, for example, the DL HARQ bit transmission defined in TS 38.213 V15.6.0.

[0132] In another embodiment, its PUCCH resource can overlap with the PUCCH format 0 resource by up to two SL HARQ bit negations of the SR, allowing the PUCCH format 0 resource with a predefined table-based cyclic shift to be used for propagation. The predefined table can be the same as, for example, the table defined in TS 38.213 V15.6.0 for DL ​​HARQ bit transmission. The predefined table differs from the predefined table used for positive SRs and SL PUCCH format 0.

[0133] In one embodiment, another approach allows the positive / negative SR in the PUCCCH format 0 resource to overlap with the PUCCCH format 1 resource by up to two SL HARQ bits, such that the SL HARQ bits are used with PUCCCH format 1. SR information may be discarded.

[0134] In one embodiment, another method allows the positive SR bits in the PUCCH format 1 resource to overlap with the SL HARQ bits in the PUCCH format 1 resource, enabling the SR PUCCH format 1 resource to be used for SL HARQ bit transmission. In another embodiment, for the negative SR bits in the PUCCH format-1 resource to overlap with the SL HARQ bits in the PUCCH format-1 resource, the SL HARQ PUCCH format-1 resource can be used for SL HARQ bit transmission. That is, SR information is carried through the on / off keying of the SR PUCCH format-1 resource.

[0135] In some embodiments, the second solution may allow the DL HARQ-ACK bit on a PUCCH format 0 / 1 resource to overlap with the SL HARQ bit on another PUCCH format 0 / 1 resource, and there are two methods for proposing UL feedback as described below.

[0136] In one embodiment, the first approach is to discard one of the DL and SL HARQ PUCCH resources. The HARQ bits associated with the discarded PUCCH resource may not be sent, and this discarding can be performed if none of the PUCCH resources can accommodate all the DL and SL HARQ bits.

[0137] In one embodiment, it can be predetermined / (pre)configured which of the DL and SL HARQ-ACK messages will be discarded. In one embodiment, it can discard the SL HARQ-ACK message and only send the DL HARQ-ACK bits.

[0138] In one embodiment, PUCCH resources associated with a specific format can be preferentially discarded. For example, when two PUCCH resources correspond to different PUCCH formats, PUCCH format-1 can be discarded.

[0139] In one embodiment, it can refer to the priority of such discarding. In one implementation, the DL HARQ-ACK bit corresponding to a high-priority DL service (e.g., URLLC service) can be distinguished by the corresponding scheduling DCI. A DCI field for explicit indication or a specified / configured RNTI can be used to scramble the scheduling DCI. Priority can be binary, i.e., low priority and high priority. If different priorities are associated with different DL HARQ-ACK bits, the highest priority among them can be assumed. In another implementation, the priority of the SL HARQ-ACK bit can be determined based on the explicit priority field in the corresponding SCI. If different priorities may be associated with different SL HARQ-ACK bits, the highest priority among them can be assumed. In another implementation, DL HARQ-ACK information corresponding to the high-priority indication can be transmitted via DCI. The DL HARQ-ACK codebook containing high-priority DL HARQ-ACK information can be transmitted on its (for DL) PUCCH resource. SL HARQ-ACK bits may be discarded. In another implementation, there may be a priority threshold for the SCI priority field. For DL ​​HARQ-ACK messages corresponding to a low-priority indication via DCI, if the SCI priority field associated with the SL HARQ-ACK bits indicates a priority lower than the priority threshold, the SL HARQ bits may be discarded. In another example, for DL ​​HARQ-ACK messages corresponding to a low-priority indication via DCI, if the SCI priority field associated with the SL HARQ-ACK can be sent on its (for SL) PUCCH resource, the SL HARQ-ACK codebook bits can indicate a priority higher than or equal to the priority threshold.

[0140] In a second method, in one embodiment, if the size of the concatenated payload is suitable for PUCCH format-0 / 1 resources, one of the PUCCH resources can be selected for transmitting the concatenated HARQ-ACK codebook, and how to select the PUCCH resource can be determined by one or a combination of the following four methods.

[0141] In one embodiment, the first approach is that the PUCCH resource associated with the fixed interface can be used for transmission. The fixed interface can be (pre-)specified / (pre-)configured.

[0142] In one embodiment, the second approach is to prioritize PUCCH resources associated with a specific format. For example, when two PUCCH resources correspond to different PUCCH formats, PUCCH format-1 can be selected.

[0143] In one embodiment, a third approach is that PUCCH resource selection can be based on the priority of the corresponding HARQ-ACK bits. Here, the same solution described above can be applied to determine which one to discard.

[0144] In a fourth embodiment, the above-described scheme can be applied to handle scenarios where long PUCCH format resources for UCI overlap with long PUCCH format resources for SL HARQ-ACK.

[0145] In one embodiment, the third solution can be applied to situations where long PUCCH format resources for UCI reporting overlap with short PUCCH format resources for SL HARQ-ACK reporting. UCI reporting overlaps with long PUCCH format resources for SL HARQ-ACK reporting. In this case, long PUCCH format resources can be selected to multiplex UCI and SL HARQ-ACK. In one example, PUCCH format 2 / 3 / 4 resources are used for UCI reporting and PUCCH format 0 / 1 resources are used for SL HARQ-ACK reporting. Therefore, based on the third solution, PUCCH format -2 / 3 / 4 resources can be selected to transmit the multiplexed UCI and SL HARQ-ACK bits.

[0146] In some embodiments, the PUCCH resources for positive / negative SR, DL HARQ bits, and SL HARQ bits overlap. In the fourth scheme, the above scheme can be used to merge HARQ-ACK bits, after which SR and HARQ-ACK bits can be reused. The schemes described here can refer to, for example, TS 38.213 V15.6.0 or other operations provided by this invention, and are not limited thereto.

[0147] The PUCCH resources used for DL ​​HARQ-ACK feedback and SL HARQ-ACK feedback can be scheduled by the BS in a UL slot with non-overlapping symbols. That is, the TDM-ed PUCCH resources in a UL slot are used for DL / SL HARQ-ACK feedback respectively.

[0148] It is worth noting that there may be scenarios where the TDM-ed PUCCH resource used for DL / SL HARQ-ACK feedback might be violated, for example, due to latency issues or errors in scheduling. Special case handling may need to be specified below.

[0149] In the case of overlapping PUCCH resources for DL / SL HARQ-ACK feedback indications, one PUCCH resource and its corresponding HARQ-ACK bit can be discarded. The scheme for selecting a PUCCH resource and its corresponding HARQ-ACK bit to be discarded can follow one or a combination of the following three schemes.

[0150] In one embodiment, a first solution is to discard the PUCCH resource associated with the fixed interface. The fixed interface can be (pre-)specified / (pre-)configured.

[0151] In a second approach, in one embodiment, PUCCH resources corresponding to different formats can be associated with different priorities. When overlapping with a higher-priority format, the lower-priority format is discarded. For example, when overlapping with a long PUCCH format resource, PUCCH format 1 resource may be discarded.

[0152] In one embodiment, a third solution can determine which one to discard based on priority. Three methods are presented below. In one embodiment, the first method is that the DLHARQ-ACK bit corresponding to a high-priority DL service (e.g., URLLC service) can be distinguished by its scheduling DCI. For example, the DCI field used to explicitly indicate or specify / configure the RNTI can be used to scramble the scheduling DCI. Priorities can be binary, i.e., low priority and high priority. If different priorities may be associated with different DL HARQ-ACK bits, the highest priority among them can be assumed.

[0153] In a second approach, another embodiment, the priority of the SL HARQ-ACK bits can be determined based on the explicit priority field in the corresponding SCI. If different priorities may be associated with different SL HARQ-ACK bits, the highest priority among them can be assumed.

[0154] In one embodiment, the DL HARQ-ACK information corresponding to the high priority indication via DCI can be transmitted on its (for DL) PUCCH resource. The SL HARQ-ACK bit may be discarded.

[0155] In a third method, another embodiment, a priority threshold for the SCI priority field may exist. For DL ​​HARQ-ACK information corresponding to a low-priority indication via DCI in the first method, if the SCI priority field associated with the SL HARQ bit indicates a priority below the priority threshold, the DL HARQ-ACK codebook may be transmitted on its (for DL) PUCCH resource. The SL HARQ bit may be discarded. In another embodiment, for DL ​​HARQ-ACK information corresponding to a low-priority indication via DCI, if the SCI priority field associated with the SL HARQ bit indicates a priority higher than or equal to the priority threshold...

[0156] Figure 7 A block diagram of a node 600 for wireless communication according to various aspects of this disclosure is shown. Figure 7 As shown, node 600 may include a transceiver 606, a processor 608, a memory 602, one or more presentation components 604, and at least one antenna 610. Node 600 may also include a radio frequency (RF) spectrum band module, a BS communication module, an NW communication module and a system communication management module, input / output (I / O) ports, I / O components, and a power supply. Figure 7 (Not explicitly stated in the document). Each of these components can communicate directly or indirectly with each other via one or more buses 624. In one implementation, node 600 can be a UE or BS performing the various functions described herein, for example, as referenced in [reference]. Figures 1 to 6 .

[0157] A transceiver 606, having a transmitter 616 (e.g., transmit / transmit circuitry) and a receiver 618 (e.g., receive / receive circuitry), can be configured to transmit and / or receive time and / or frequency resource allocation information. In one embodiment, transceiver 606 can be configured to transmit in different types of subframes and time slots, including but not limited to available, unavailable, and flexibly available subframe and time slot formats. Transceiver 606 can be configured to receive data and control channels.

[0158] Node 600 may include a variety of calculator-readable media. Calculator-readable media can be any available media accessible to Node 600, and includes volatile (and non-volatile) media and removable (and non-removable) media. By way of example and not limitation, calculator-readable media may include calculator storage media and communication media. Calculator storage media may include volatile (and non-volatile) and removable (and non-removable) media implemented according to any method or technology used for storing calculator-readable information.

[0159] Calculator storage media include RAM, ROM, EEPROM, flash memory (or other storage technologies), CD-ROM, DVD (or other optical disc storage), magnetic tape cartridges, magnetic tape, disk storage (or other magnetic storage devices), etc. Calculator storage media does not include transmitted data signals. Communication media typically embody calculator-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and include any information transmission medium. The term "modulated data signal" can refer to a signal having one or more of its characteristics, set or altered in a manner that encodes information in the signal. By way of example and not limitation, communication media can include wired media, such as wired NW or direct wired connections, and wireless media, such as acoustic, RF, infrared, and other wireless media. Any combination of the above should also be included within the scope of calculator-readable media.

[0160] Memory 602 may include a calculator storage medium in the form of volatile and / or non-volatile memory. Memory 602 may be removable, non-removable, or a combination thereof. For example, memory 602 may include solid-state memory, hard disk drive, optical disk drive, etc. Figure 7 As shown, memory 602 may store calculator-readable and / or executable instructions 614 (e.g., software code). Instructions 614 are configured to cause processor 608 to perform various functions described herein, for example, referencing Figures 1 to 6 Alternatively, instruction 614 may not be directly executed by processor 608, but can be configured to cause node 600 (e.g., when compiled and executed) to perform the various functions described herein.

[0161] Processor 608 (e.g., having processing circuitry) may include intelligent hardware devices, central processing units (CPUs), microcontrollers, ASICs, etc. Processor 608 may include memory. Processor 608 can process data 612 and instructions 614 received from memory 602, as well as information transmitted via transceiver 606, baseband communication module, and / or NW communication module. Processor 608 can also process information to be transmitted to transceiver 606 for transmission via antenna 610, or to NW communication module for transmission to CN.

[0162] One or more presentation components 604 can present data indications to a person or other device. Examples of presentation components 604 may include display devices, speakers, printing components, vibration components, etc.

[0163] In summary, several embodiments handle the feedback of the SL HARQ-ACK bit through the UP PUCCH resource. Specifically, the solution addresses the following issues.

[0164] First, for NACK-only and ACK / NACK-based feedback in multicast scenarios, determine the SL HARQ-ACK state when no signal is received from the SL feedback channel.

[0165] Secondly, determine the SL HARQ-ACK bits to be reported via UL PUCCH resource. Details include how to generate HARQ-ACK bits for SL TB and how to reuse HARQ-ACK bits corresponding to different SL TBs.

[0166] Third, payload information is determined when PUCCH resources used for UL UCI and SL HARQ-ACK feedback overlap in the time domain. Details include how to select a PUCCH resource for transmission when only one transmission is allowed, and how to multiplex UL UCI and SL HARQ-ACK information on the selected PUCCH resource.

[0167] It is evident from the above description that various techniques can be used to implement the concepts without departing from the scope of the concepts described herein. Furthermore, although these concepts have been specifically described with reference to certain embodiments, those skilled in the art will recognize that changes in form and detail can be made without departing from the scope of those concepts. Therefore, the described embodiments are to be considered illustrative rather than restrictive in all respects. It should also be understood that this application is not limited to the specific embodiments described above, and many rearrangements, modifications, and substitutions are possible without departing from the scope of the invention.

Claims

1. A method performed by a user equipment, the method comprising: A current sidelink entity downlink control channel is received from a base station, wherein the current sidelink entity downlink control channel provides scheduling information for at least one sidelink transmission sent from the user equipment to at least one other user equipment; The value of a side link allocation indication field is obtained from the current side link entity downlink control channel, wherein the value of the side link allocation indication field indicates the cumulative number from a set of side link entity downlink control channels received from the base station to the current side link entity downlink control channel; A hybrid automatic repeat request codebook is constructed at least in part based on the sidelink allocation indication field. The hybrid automatic repeat request codebook includes multiple hybrid automatic repeat request-acknowledgment bits for a number of sidelink transmissions scheduled by the downlink control channel of the set of sidelink entities received from the base station. Each of the sidelink transmissions requires feedback, and each hybrid automatic repeat request-acknowledgment bit indicates whether the at least one other user equipment has successfully received the corresponding one of the sidelink transmissions. The hybrid automatic repeat request codebook is sent to the base station. Wherein, the number of sidelink transmissions includes the at least one sidelink transmission, and The set of sidelink entity downlink control channels includes the current sidelink entity downlink control channel.

2. The method according to claim 1, wherein, The at least one side link transmission corresponds to a transmission block.

3. The method according to claim 1, wherein, The multiple hybrid automatic repeat request-acknowledgment bits in the hybrid automatic repeat request codebook are processed through a bundling operation and / or a multiplexing operation.

4. The method according to claim 1, wherein, The value of the sidelink allocation indication field in the downlink control channel of the current sidelink entity determines the order of the hybrid automatic repeat request-acknowledgment bits in the hybrid automatic repeat request codebook.

5. A user equipment in a wireless communication system including a base station, the user equipment comprising: One transceiver; A memory containing computer-executable instructions; and At least one processor, coupled to the transceiver and the memory, the computer is capable of executing instructions to cause the user equipment to: The transceiver receives a current sidelink entity downlink control channel from a base station, wherein the current sidelink entity downlink control channel provides scheduling information for at least one sidelink transmission sent from the user equipment to at least one other user equipment; The value of a side link allocation indication field is obtained from the current side link entity downlink control channel, wherein the value of the side link allocation indication field indicates the cumulative number from a set of side link entity downlink control channels received from the base station to the current side link entity downlink control channel; A hybrid automatic repeat request codebook is constructed at least in part based on the sidelink allocation indication field. The hybrid automatic repeat request codebook includes a plurality of hybrid automatic repeat request-acknowledgment bits for a number of sidelink transmissions scheduled by the downlink control channel of the set of sidelink entities received from the base station. Each of the number of sidelink transmissions requires feedback. Each hybrid automatic repeat request-acknowledgment bit indicates whether the at least one other user equipment has successfully received the corresponding one of the number of sidelink transmissions. as well as The transceiver sends the hybrid automatic repeat request codebook to the base station, wherein the number of sidelink transmissions includes at least one sidelink transmission, and The set of sidelink entity downlink control channels includes the current sidelink entity downlink control channel.

6. The user equipment according to claim 5, wherein, The at least one side link transmission corresponds to a transmission block.

7. The user equipment according to claim 5, wherein, The multiple hybrid automatic repeat request-acknowledgment bits in the hybrid automatic repeat request codebook are processed through a bundling operation and / or a multiplexing operation.

8. The user equipment according to claim 5, wherein, The value of the sidelink allocation indication field in the downlink control channel of the current sidelink entity determines the order of the hybrid automatic repeat request-acknowledgment bits in the hybrid automatic repeat request codebook.

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