Method and apparatus for performing sidelink communication in a wireless communication system - Patents.com

Abstract

A method and an apparatus for performing communication in a wireless communication system are disclosed. A method for performing communication by a first terminal according to an embodiment of the present disclosure may include receiving configuration information related to a plurality of sidelink (SL) resource pools and a plurality of resource block (RB) sets from a base station, detecting and triggering a consistent SL listen before talk (LBT) failure for at least one of a first SL resource pool or a first RB set among the plurality of SL resource pools and the plurality of RB sets, and triggering an SL resource reselection to select a second SL resource pool or a second RB set from the plurality of resource pools and the plurality of RB sets based on the triggered consistent SL LBT failure not being cancelled.

Description

[Technical field]

[0001] The present disclosure relates to wireless communication systems, and more particularly, to a method and apparatus for performing sidelink communication in a wireless communication system. [Background technology]

[0002] Mobile communication systems were developed to provide voice services while ensuring user activity. However, the scope of mobile communication systems has expanded beyond voice to data services, and currently, resource shortages are occurring due to the explosive increase in traffic, and users are demanding faster services, so there is a demand for more advanced mobile communication systems.

[0003] The requirements for the next generation mobile communication system are to accommodate large and explosive data traffic, dramatically increase the transmission rate per user, accommodate a significantly increased number of connected devices, and support very low end-to-end latency and high energy efficiency. To this end, various technologies such as Dual Connectivity, Massive Multiple Input Multiple Output (MAMO), In-band Full Duplex, Non-Orthogonal Multiple Access (NOMA), super wideband support, and Device Networking are being researched. Summary of the Invention [Problem to be solved by the invention]

[0004] A technical problem of the present disclosure is to provide a method and apparatus for performing sidelink communication in a wireless communication system.

[0005] A technical problem of the present disclosure is to provide a method and apparatus for detecting SL LBT in units of SL resource pools and / or RB sets.

[0006] A technical problem of the present disclosure is to provide a method and apparatus for triggering a SL resource reselection procedure when a consistent LBT failure is triggered.

[0007] The technical problems to be achieved by the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains from the following description. [Means for solving the problem]

[0008] As one embodiment of the present disclosure, a method performed by a first terminal in a wireless communication system may include: receiving configuration information related to a plurality of sidelink (SL) resource pools and a plurality of resource block (RB) sets from a base station; detecting and triggering a consistent SL listen before talk (SL LBT) failure for at least one of a first SL resource pool or a first RB set among the plurality of SL resource pools and the plurality of RB sets; and triggering an SL resource reselection to select a second SL resource pool or a second RB set from among the plurality of resource pools and the plurality of RB sets based on the triggered consistent SL LBT failure not being canceled.

[0009] As one embodiment of the present disclosure, a method performed by a base station in a wireless communication system includes a step of transmitting configuration information related to a plurality of sidelink (SL) resource pools and a plurality of resource block (RB) sets to a first terminal, and a step of receiving from the first terminal a MAC CE related to a consistent SL listen before talk (LBT) failure for at least one of the plurality of SL resource pools and the plurality of RB sets, the first terminal may trigger an SL resource reselection to select a second SL resource pool or a second RB set from the plurality of resource pools and the plurality of RB sets based on the triggered consistent SL LBT failure not being canceled. Effect of the Invention

[0010] According to an embodiment of the present disclosure, a method and apparatus for performing sidelink communication in a wireless communication system may be provided.

[0011] As an embodiment of the present disclosure, a method and apparatus for detecting SL LBT in units of SL resource pools and / or RB sets may be provided.

[0012] As an embodiment of the present disclosure, a method and apparatus may be provided for triggering a SL resource reselection procedure by triggering a consistent LBT failure.

[0013] As one embodiment of the present disclosure, by detecting LBT failure on a resource pool or RB set basis within an SL BWP in a sidelink of an unlicensed band, a base station / terminal can operate resources based on a smaller range of congestion detection.

[0014] The effects obtained from the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains from the following description. [Brief description of the drawings]

[0015] The accompanying drawings, which are included as part of the detailed description to aid in understanding the present disclosure, provide examples of the present disclosure and, together with the detailed description, explain the technical features of the present disclosure.

[0016] [Figure 1] FIG. 1 is a diagram illustrating the structure of a wireless communication system to which the present disclosure can be applied. [Diagram 2] FIG. 1 illustrates a frame structure in a wireless communication system to which the present disclosure can be applied. [Diagram 3] FIG. 1 illustrates a resource grid in a wireless communication system to which the present disclosure can be applied. [Figure 4] FIG. 1 is a diagram illustrating a physical resource block in a wireless communication system to which the present disclosure can be applied. [Diagram 5] FIG. 1 illustrates a slot structure in a wireless communication system to which the present disclosure can be applied. [Figure 6] 1 is a diagram illustrating physical channels used in a wireless communication system to which the present disclosure can be applied and a general signal transmission / reception method using the physical channels. [Figure 7] FIG. 1 is a diagram showing a procedure for performing V2X or SL communication in a transmission mode in a wireless communication system to which the present disclosure can be applied. [Figure 8] FIG. 11 is a diagram illustrating a cast type for V2X or SL communication in a wireless communication system to which the present disclosure can be applied. [Figure 9] FIG. 2 is a diagram for explaining a process in which a first terminal performs communication according to an embodiment of the present disclosure. [Figure 10] FIG. 13 is a diagram for explaining a process in which a base station performs communication according to one embodiment of the present disclosure. [Figure 11] A diagram for explaining a signaling procedure between a base station, a first terminal, and a second terminal according to one embodiment of the present disclosure. [Figure 12] FIG. 13 is a diagram for explaining a (SL)LBT failure MAC CE structure according to one embodiment of the present disclosure. [Figure 13] 1 is a block diagram illustrating a wireless communication device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description disclosed below together with the accompanying drawings is intended to describe exemplary embodiments of the present disclosure, and is not intended to show the only embodiment in which the present disclosure can be implemented. The detailed description below includes specific details to provide a complete understanding of the present disclosure. However, it is understood by those skilled in the art that the present disclosure can be implemented without such specific details.

[0018] In some cases, in order to avoid obscuring the concepts of the present disclosure, known structures and devices may be omitted or may be shown in the form of a block diagram focusing on the core functions of each structure and device.

[0019] In this disclosure, when an element is "coupled," "coupled," or "connected" to another element, this can include a direct connection as well as an indirect connection where there is still another element between them. Also, in this disclosure, the terms "including" or "having" specify the presence of stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0020] In this disclosure, terms such as "first" and "second" are used only to distinguish one component from another component, and are not used to limit the components, and do not limit the order or importance of the components unless otherwise specified. Therefore, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0021] The terms used in this disclosure are for the purpose of describing particular embodiments and are not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular form is intended to include the plural form unless the context dictates otherwise. The term "and / or" used in this disclosure means that one of the associated listed items may be included, or any and all possible combinations of two or more of them. Also, in this disclosure, " / " between words has the same meaning as "and / or" unless otherwise specified.

[0022] The present disclosure is described with respect to a wireless communication network or wireless communication system, and operations performed in the wireless communication network may be performed in a process in which a device (e.g., a base station) that manages the wireless communication network controls the network and transmits or receives signals, or in a process in which a terminal coupled to the wireless network transmits or receives signals to or between the network.

[0023] In this disclosure, transmitting or receiving a channel includes transmitting or receiving information or signals on that channel. For example, transmitting a control channel means transmitting control information or signals on the control channel. Similarly, transmitting a data channel means transmitting data information or signals on the data channel.

[0024] In the following, downlink (DL) means communication from a base station to a terminal, and uplink (UL) means communication from a terminal to a base station. In the downlink, a transmitter may be a part of the base station, and a receiver may be a part of the terminal. In the uplink, a transmitter may be a part of the terminal, and a receiver may be a part of the base station. The base station may be expressed as a first communication device, and the terminal may be expressed as a second communication device. A base station (BS) may be replaced with terms such as a fixed station, Node B, eNB (evolved-NodeB), gNB (Next Generation NodeB), BTS (base transceiver system), access point (AP), network (5G network), AI (Artificial Intelligence) system / module, RSU (road side unit), robot, drone (UAV: Unmanned Aerial Vehicle), AR (Augmented Reality) device, VR (Virtual Reality) device, etc. In addition, a terminal may be fixed or mobile, and may be replaced with terms such as User Equipment (UE), Mobile Station (MS), user terminal (UT), Mobile Subscriber Station (MSS), Subscriber Station (SS), Advanced Mobile Station (AMS), Wireless terminal (WT), Machine-Type Communication (MTC) device, Machine-to-Machine (M2M) device, Device-to-Device (D2D) device, vehicle, road side unit (RSU), robot, Artificial Intelligence (AI) module, drone (UAV: Unmanned Aerial Vehicle), Augmented Reality (AR) device, Virtual Reality (VR) device, etc.

[0025] The following technologies may be used for various wireless access systems such as CDMA, FDMA, TDMA, OFDMA, SC-FDMA, etc. CDMA may be implemented by radio technologies such as Universal Terrestrial Radio Access (UTRA) and CDMA2000. TDMA may be implemented by radio technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented by radio technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA), etc. UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3GPP (registered trademark) (3rd Generation Partnership Project) LTE (Long Term Evolution) is a part of E-UMTS (Evolved UMTS) that uses E-UTRA, and LTE-A (Advanced) / LTE-A pro is an evolved version of 3GPP LTE. 3GPP NR (New Radio or New Radio Access Technology) is an evolved version of 3GPP LTE / LTE-A / LTE-A pro.

[0026] For clarity of explanation, the following description will be based on a 3GPP communication system (e.g., LTE-A, NR), but the technical idea of ​​the present disclosure is not limited thereto. LTE refers to technology after 3GPP TS (Technical Specification) 36.xxx Release 8. In detail, LTE technology after 3GPP TS 36.xxx Release 10 is called LTE-A, and LTE technology after 3GPP TS 36.xxx Release 13 is called LTE-A pro. 3GPP NR refers to technology after TS 38.xxx Release 15. LTE / NR may be called a 3GPP system. "xxx" refers to a standard document detail number. LTE / NR may be called a 3GPP system. For background technology, terms, abbreviations, etc. used in the description of the present disclosure, reference may be made to matters described in standard documents published before the present disclosure. For example, the following documents may be referenced.

[0027] In 3GPP LTE, reference can be made to TS 36.211 (physical channels and modulation), TS 36.212 (multiplexing and channel coding), TS 36.213 (physical layer procedures), TS 36.300 (general description), and TS 36.331 (radio resource control).

[0028] For 3GPP NR, reference can be made to TS 38.211 (Physical channels and modulation), TS 38.212 (Multiplexing and channel coding), TS 38.213 (Physical layer procedures for control), TS 38.214 (Physical layer procedures for data), TS 38.300 (General description of NR and NG-RAN (New Generation-Radio Access Network)), and TS 38.331 (Radio resource control protocol standard).

[0029] The following terminology abbreviations may be used in this disclosure:

[0030] - BM: Beam management

[0031] - CQI: channel quality indicator

[0032] - CRI: channel state information- reference signal resource indicator

[0033] - CSI: channel state information

[0034] - CSI-IM: channel state information-interference measurement

[0035] - CSI-RS: Channel state information-reference signal

[0036] - DMRS: Demodulation Reference Signal

[0037] - FDM: Frequency division multiplexing

[0038] - FFT: Fast Fourier transform

[0039] - IFDMA: Interleaved frequency division multiple access

[0040] - IFFT: inverse fast Fourier transform

[0041] - L1-RSRP: Layer 1 reference signal received power

[0042] - L1-RSRQ: Layer 1 reference signal received quality

[0043] - MAC: medium access control

[0044] - NZP: non-zero power

[0045] - OFDM: Orthogonal frequency division multiplexing

[0046] - PDCCH: physical downlink control channel

[0047] - PDSCH: physical downlink shared channel

[0048] - PMI: Precoding matrix indicator

[0049] - RE: resource element

[0050] - RI: Rank indicator

[0051] - RRC: Radio resource control

[0052] - RSSI: received signal strength indicator

[0053] - Rx: Reception

[0054] - QCL: quasi co-location

[0055] - SINR: signal to interference and noise ratio

[0056] - SSB (or SS / PBCH block): Synchronization signal block (including primary synchronization signal (PSS), secondary synchronization signal (SSS) and physical broadcast channel (PBCH))

[0057] - TDM: time division multiplexing

[0058] - TRP: transmission and reception point

[0059] - TRS: Tracking reference signal

[0060] - Tx: transmission

[0061] - UE: User Equipment

[0062] - ZP: Zero power

[0063] System in general

[0064] As more communication devices require larger communication capacity, the need for improved mobile broadband communication compared to existing radio access technology (RAT) is emerging. Massive MTC (Machine Type Communications), which connects multiple devices and objects to provide various services anytime and anywhere, is also one of the major issues considered in next-generation communication. In addition, communication system design considering reliability and latency-sensitive services / terminals is also being discussed. Thus, the introduction of next-generation RATs considering eMBB (enhanced mobile broadband communication), Mmtc (massive MTC), URLLC (Ultra-Reliable and Low Latency Communication), etc. is being discussed, and for convenience in this disclosure, the technology is referred to as NR. NR is an expression representing an example of 5G RAT.

[0065] New RAT systems including NR use an OFDM transmission scheme or a similar transmission scheme. The new RAT system may follow OFDM parameters different from those of LTE. Or, the new RAT system may follow the existing LTE / LTE-A numerology but support a larger system bandwidth (e.g., 100 MHz). Or, one cell may support multiple numerologies. That is, terminals operating with different numerologies may coexist in one cell.

[0066] A numerology corresponds to a subcarrier spacing in the frequency domain. Different numerologies can be defined by scaling the reference subcarrier spacing by an integer N.

[0067] FIG. 1 illustrates the structure of a wireless communication system to which the present disclosure can be applied.

[0068] Referring to FIG. 1, the NG-RAN is composed of gNBs that provide an NG-Radio Access (NG-RA) user plane (i.e., a new access stratum (AS) sublayer / Packet Data Convergence Protocol (PDCP) / Radio Link Control (RLC) / MAC / PHY) and control plane (RRC) protocol termination for the UE. The gNBs are interconnected via an Xn interface. The gNBs are also connected to a New Generation Core (NGC) via an NG interface. More specifically, the gNBs are connected to an Access and Mobility Management Function (AMF) via an N2 interface and to a User Plane Function (UPF) via an N3 interface.

[0069] FIG. 2 illustrates a frame structure in a wireless communication system to which the present disclosure can be applied.

[0070] The NR system can support multiple numerologies, where the numerology may be defined by subcarrier spacing and cyclic prefix (CP) overhead. In this case, the multiple subcarrier spacing may be derived by scaling the base (reference) subcarrier spacing by an integer N (or μ). In addition, the numerology used may be selected independently of the frequency band, although it is assumed that very low subcarrier spacing is not used at very high carrier frequencies. In addition, various frame structures with multiple numerologies may be supported in the NR system.

[0071] The following describes OFDM numerologies and frame structures that can be considered in the NR system. Multiple OFDM numerologies supported in the NR system may be defined as shown in Table 1 below.

[0072] [Table 1]

[0073] NR supports multiple numerologies (or subcarrier spacing (SCS)) to support various 5G services. For example, when the SCS is 15 kHz, it supports a wide area in a traditional cellular band, when the SCS is 30 kHz / 60 kHz, it supports dense urban areas, lower latency, and wider carrier bandwidth, and when the SCS is 60 kHz or higher, it supports a bandwidth larger than 24.25 GHz to overcome phase noise. The NR frequency band is defined as two types of frequency ranges (FR1, FR2). FR1 and FR2 may be configured as shown in Table 2 below. Also, FR2 can mean millimeter wave (mmW).

[0074] [Table 2]

[0075] In relation to the frame structure in the NR system, the sizes of the various fields in the time domain are T c =1 / (Δf max N f ) where Δf max =480 10 3 Hz and N f= 4096. Downlink and uplink transmissions are f =1 / (Δf max N f / 100)·T c The radio frame is organized into radio frames each having a duration of T sf =(Δf max N f / 1000)·T c In this case, there may be one set of frames for the uplink and one set of frames for the downlink. Also, the transmission from the terminal in the uplink frame number i starts T TA =(N TA +N TA,offset )T c For a subcarrier spacing configuration μ, a slot is allocated within a subframe. s μ ∈{0,...,N slot subframe,μ -1}, and n s,f μ ∈{0,...,N slot frame,μ -1}. A slot is numbered in increasing order. symb slot It consists of N consecutive OFDM symbols. symb slot is determined by the CP. s μ The start of OFDM symbol n s μ N symb slotNot all terminals can transmit and receive at the same time, which means that not all OFDM symbols in a downlink slot or uplink slot can be used.

[0076] Table 3 shows the number of OFDM symbols per slot (N symb slot ), the number of slots per radio frame (N slot frame,μ ), the number of slots per subframe (N slot subframe,μ ), and Table 4 shows the number of OFDM symbols per slot, the number of slots per radio frame, and the number of slots per subframe in the extended CP.

[0077] [Table 3]

[0078] [Table 4]

[0079] FIG. 2 shows an example where μ=2 (SCS is 60 kHz), and referring to Table 3, one subframe can include four slots. One subframe={1, 2, 4} slots shown in FIG. 2 is an example, and the number of slots that can be included in one subframe is defined as shown in Table 3 or Table 4. Also, a mini-slot can include 2, 4, or 7 symbols, or more or less symbols. In relation to physical resources in the NR system, antenna ports, resource grids, resource elements, resource blocks, carrier parts, and the like may be considered. Hereinafter, the physical resources that can be considered in the NR system will be specifically described.

[0080] First, with respect to antenna ports, the antenna ports are defined such that the channel on which a symbol on an antenna port is carried can be inferred from the channel on which another symbol on the same antenna port is carried. If the large-scale properties of the channel on which a symbol on one antenna port is carried can be inferred from the channel on which a symbol on the other antenna port is carried, the two antenna ports are said to be in a quasi co-located (QC / QCL) relationship. Here, the large-scale properties include one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

[0081] FIG. 3 illustrates a resource grid in a wireless communication system to which the present disclosure can be applied.

[0082] Referring to FIG. 3, the resource grid is divided into N RB μ N sc RB Each subframe consists of 14·2 subcarriers. μ In the present embodiment, the OFDM symbol is used as an example, but is not limited to, an OFDM symbol. RB μ N sc RB One or more resource grids consisting of subcarriers and two μ N symb (μ) OFDM symbols, where N RB μ ≦N RB max,μ The above N RB max,μ represents the maximum transmission bandwidth, which may vary not only with numerology but also between uplink and downlink. In this case, one resource grid may be set for μ and antenna port p. Each element of the resource grid for μ and antenna port p is called a resource element, and is represented by an index pair: JPEG2025514210000006.jpg617, where k=0,...,N RB μ N sc RB -1 is the index in the frequency domain, JPEG2025514210000007.jpg677 represents the position of the symbol within a subframe. When indicating a resource element in a slot, the index pair (k,l) is used.

[0083] where l=0,...,N symb μ μ and the resource element for antenna port p. JPEG2025514210000008.jpg617 is a complex value JPEG2025514210000009.jpg911. If there is no risk of confusion or if a specific antenna port or numerology is not specified, the indexes p and μ may be dropped, so that the complex value is JPEG2025514210000010.jpg1130. Also, a resource block (RB) is N sc RB = 12 consecutive subcarriers.

[0084] Point A serves as a common reference point for the resource block grid and is obtained as follows:

[0085] - offsetToPointA for the primary cell (PCell) downlink indicates the frequency offset between point A and the lowest subcarrier of the lowest resource block that overlaps with the SS / PBCH block used by the terminal for initial cell selection. It is expressed in resource block units assuming 15 kHz subcarrier spacing for FR1 and 60 kHz subcarrier spacing for FR2.

[0086] - absoluteFrequencyPointA indicates the frequency-location of point A expressed as in ARFCN (absolute radio-frequency channel number).

[0087] Common resource blocks are numbered from 0 upwards in the frequency domain for a subcarrier spacing setting μ. The center of subcarrier 0 of common resource block 0 for a subcarrier spacing setting μ coincides with 'point A'. Common resource block number n CRB μThe relationship between k, l and the resource element (k, l) for the subcarrier spacing setting μ is given by the following Equation 1.

[0088]

number

[0089] In Equation 1, k is defined relative to point A such that k=0 corresponds to the subcarrier centered at point A. A physical resource block is a number ranging from 0 to N within a bandwidth part (BWP). BWP,i size,μ The numbering is from -1 to i, where i is the number of the BWP. PRB and common resource block n CRB The relationship between is given by Equation 2 below.

[0090]

number

[0091] N BWP,i start,μ is the common resource block where the BWP starts relative to common resource block 0.

[0092] Fig. 4 illustrates a physical resource block in a wireless communication system to which the present disclosure can be applied, and Fig. 5 illustrates a slot structure in a wireless communication system to which the present disclosure can be applied.

[0093] 4 and 5, a slot includes a number of symbols in the time domain. For example, in the general CP, one slot includes seven symbols, while in the extended CP, one slot includes six symbols.

[0094] A carrier includes multiple subcarriers in the frequency domain. A resource block (RB) is defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain. A bandwidth part (BWP) is defined as multiple consecutive (physical) resource blocks in the frequency domain and may correspond to one numerology (e.g., SCS, CP length, etc.). A carrier may include up to N (e.g., 5) BWPs. Data communication is performed in the activated BWPs, and only one BWP may be activated for one terminal. Each element in the resource grid is called a resource element (RE), and one complex symbol may be mapped to it.

[0095] The NR system may support up to 400 MHz per component carrier (CC). If a terminal operating in such a wideband CC always operates with the radio frequency (RF) chip for the entire CC turned on, the terminal battery consumption may increase. Alternatively, considering various use cases (e.g., eMBB, URLLC, Mmtc, V2X, etc.) operating in one wideband CC, different numerologies (e.g., subcarrier spacing, etc.) may be supported for each frequency band in the CC. Alternatively, the capability for maximum bandwidth may differ for each terminal. In consideration of this, the base station may instruct the terminal to operate only in a part of the bandwidth rather than the entire bandwidth of the wideband CC, and the part of the bandwidth is defined as a bandwidth part (BWP) for convenience. The BWP may be composed of continuous RBs on the frequency axis and may correspond to one numerology (e.g., subcarrier spacing, CP length, slot / minislot interval).

[0096] Meanwhile, the base station can set multiple BWPs even within one CC set in the terminal. For example, a BWP occupying a relatively small frequency region can be set in the PDCCH monitoring slot, and the PDSCH indicated by the PDCCH can be scheduled on a larger BWP. Alternatively, when UEs are concentrated in a specific BWP, other BWPs can be set in some terminals for load balancing. Alternatively, in consideration of frequency domain inter-cell interference cancellation between adjacent cells, a part of the spectrum of the entire bandwidth can be excluded and both BWPs can be set in the same slot. That is, the base station can set at least one DL / UL BWP in the terminal associated with the wideband CC. The base station can activate at least one DL / UL BWP among the DL / UL BWPs set at a specific time (by L1 signaling, MAC CE (Control Element), RRC signaling, etc.). Also, the base station may instruct switching to another configured DL / UL BWP (by L1 signaling, MAC CE, RRC signaling, etc.). Or, the base station may switch to a predetermined DL / UL BWP when a timer value expires on a timer basis. In this case, the activated DL / UL BWP is defined as an active DL / UL BWP. However, in a situation where the UE is performing an initial access process or before an RRC connection is set up, the UE may not be able to receive the configuration for the DL / UL BWP. In such a situation, the DL / UL BWP assumed by the UE is defined as an initially active DL / UL BWP.

[0097] FIG. 6 illustrates examples of physical channels used in a wireless communication system to which the present disclosure can be applied, and a general signal transmission / reception method using the physical channels.

[0098] In a wireless communication system, a terminal receives information from a base station through a downlink, and transmits information to the base station through an uplink. Information transmitted and received between the base station and the terminal includes data and various control information, and various physical channels exist depending on the type / purpose of the information they transmit and receive.

[0099] When a terminal is powered on or newly enters a cell, the terminal performs an initial cell search operation such as synchronizing with a base station (S601). To this end, the terminal receives a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) from the base station to synchronize with the base station and obtain information such as a cell identifier (ID). After that, the terminal receives a physical broadcast channel (PBCH) from the base station to obtain broadcast information within the cell. Meanwhile, the terminal can receive a downlink reference signal (DL RS) during the initial cell search stage to check the downlink channel state.

[0100] After completing the initial cell search, the terminal receives a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) based on the information carried on the PDCCH, and can obtain more specific system information (S602).

[0101] Meanwhile, when the terminal first connects to the base station or has no radio resources for signal transmission, the terminal can perform a random access procedure (RACH: Random Access Procedure) to the base station (steps S603 to S606). To this end, the terminal can transmit a specific sequence as a preamble on a physical random access channel (PRACH: Physical Random Access Channel) (S603 and S605) and receive a response message to the preamble on a PDCCH and a corresponding PDSCH (S604 and S606). In the case of a contention-based RACH, a contention resolution procedure can also be performed.

[0102] After performing the above-mentioned procedures, the terminal can then perform PDCCH / PDSCH reception (S607) and Physical Uplink Shared Channel (PUSCH) / Physical Uplink Control Channel (PUCCH) transmission (S608) as a general uplink / downlink signal transmission procedure. In particular, the terminal receives Downlink Control Information (DCI) through the PDCCH. Here, the DCI includes control information such as resource allocation information for the terminal, and has different formats depending on its purpose.

[0103] Meanwhile, control information that a terminal transmits to a base station in an uplink or that the terminal receives from a base station includes downlink / uplink ACK / NACK (Acknowledgement / Non-Acknowledgement) signals, CQI (Channel Quality Indicator), PMI (Precoding Matrix Indicator), RI (Rank Indicator), etc. In a 3GPP LTE system, a terminal can transmit the above-mentioned control information such as CQI / PMI / RI in a PUSCH and / or a PUCCH.

[0104] Table 5 shows an example of a DCI format in an NR system.

[0105] [Table 5]

[0106] Referring to Table 5, DCI formats 0_0, 0_1, and 0_2 may include resource information related to PUSCH scheduling (e.g., UL / SUL (Supplementary UL), frequency resource allocation, time resource allocation, frequency hopping, etc.), transport block (TB) related information (e.g., MCS (Modulation Coding and Scheme), NDI (New Data Indicator), RV (Redundancy Version), etc.), HARQ (Hybrid- Automatic Repeat and request) related information (e.g., process number, DAI (Downlink Assignment Index), PDSCH-HARQ feedback timing, etc.), multiple antenna related information (e.g., DMRS sequence initialization information, antenna port, CSI request, etc.), and power control information (e.g., PUSCH power control, etc.), and the control information included in each of the DCI formats may be predefined.

[0107] DCI format 0_0 is used for scheduling PUSCH in one cell. Information included in DCI format 0_0 is CRC (cyclic redundancy check) scrambled by C-RNTI (Cell RNTI: Cell Radio Network Temporary Identifier), CS-RNTI (Configured Scheduling RNTI), or MCS-C-RNTI (Modulation Coding Scheme Cell RNTI) and transmitted.

[0108] DCI format 0_1 ​​is used to indicate to a terminal the scheduling of one or more PUSCHs in one cell or downlink feedback information of a configured grant (CG). Information included in DCI format 0_1 ​​is CRC scrambled by C-RNTI, CS-RNTI, SP-CSI-RNTI (Semi-Persistent CSI RNTI), or MCS-C-RNTI and transmitted.

[0109] DCI format 0_2 is used for scheduling the PUSCH in one cell. Information included in DCI format 0_2 is CRC scrambled by the C-RNTI, CS-RNTI, SP-CSI-RNTI, or MCS-C-RNTI and transmitted.

[0110] Next, DCI formats 1_0, 1_1, and 1_2 may include resource information related to PDSCH scheduling (e.g., frequency resource allocation, time resource allocation, VRB (virtual resource block)-PRB (physical resource block) mapping, etc.), transmission block (TB) related information (e.g., MCS, NDI, RV, etc.), HARQ related information (e.g., process number, DAI, PDSCH-HARQ feedback timing, etc.), multiple antenna related information (e.g., antenna port, TCI (transmission configuration indicator), SRS (sounding reference signal) request, etc.), PUCCH related information (e.g., PUCCH power control, PUCCH resource indicator, etc.), and the control information included in each of the DCI formats may be pre-defined.

[0111] DCI format 1_0 is used for scheduling the PDSCH in one DL cell. Information included in DCI format 1_0 is CRC scrambled by the C-RNTI, CS-RNTI, or MCS-C-RNTI and transmitted.

[0112] DCI format 1_1 is used for scheduling the PDSCH in one cell. Information included in DCI format 1_1 is CRC scrambled by the C-RNTI, CS-RNTI, or MCS-C-RNTI and transmitted.

[0113] DCI format 1_2 is used for scheduling the PDSCH in one cell. Information included in DCI format 1_2 is CRC scrambled by the C-RNTI, CS-RNTI, or MCS-C-RNTI and transmitted.

[0114] V2X (vehicle-to-everything) / Sidelink (SL) communication

[0115] FIG. 7 shows a procedure for performing V2X or SL communication in a transmission mode in a wireless communication system to which the present disclosure can be applied.

[0116] The embodiment of Fig. 7 may be combined with various embodiments of the present disclosure. In various embodiments of the present disclosure, the transmission mode may be referred to as a mode or a resource allocation mode. Hereinafter, for convenience of description, the transmission mode in LTE may be referred to as an LTE transmission mode, and the transmission mode in NR may be referred to as an NR resource allocation mode.

[0117] For example, Fig. 7(a) illustrates a UE operation associated with LTE transmission mode 1 or LTE transmission mode 3. Or, for example, Fig. 7(a) illustrates a UE operation associated with NR resource allocation mode 1. For example, LTE transmission mode 1 may be applied to general SL communication, and LTE transmission mode 3 may be applied to V2X communication.

[0118] For example, FIG. 7(b) illustrates UE operation associated with LTE transmission mode 2 or LTE transmission mode 4. Or, for example, FIG. 7(b) illustrates UE operation associated with NR resource allocation mode 2.

[0119] Referring to Figure 7 (a), in LTE transmission mode 1, LTE transmission mode 3, or NR resource allocation mode 1, a base station may schedule SL resources to be used by a UE for SL transmission (S8000). For example, the base station may transmit information related to SL resources and / or information related to UL resources to a first UE. For example, the UL resources may include PUCCH resources and / or PUSCH resources. For example, the UL resources may be resources for reporting SL HARQ feedback to the base station.

[0120] For example, the first UE may receive information related to dynamic grant (DG) resources and / or information related to configured grant (CG) resources from the base station. For example, the CG resources may include CG type 1 resources or CG type 2 resources. In the present disclosure, the DG resources may be resources that the base station configures / assigns to the first UE using DCI. In the present disclosure, the CG resources may be (periodic) resources that the base station configures / assigns to the first UE using DCI and / or RRC messages. For example, in the case of CG type 1 resources, the base station may send an RRC message including information related to the CG resources to the first UE. For example, in the case of CG type 2 resources, the base station may send an RRC message including information related to the CG resources to the first UE, and the base station may send a DCI related to activation or release of the CG resources to the first UE.

[0121] The first UE may transmit a PSCCH (eg, Sidelink Control Information (SCI) or 1st-stage SCI) to the second UE based on the resource scheduling (S8010).

[0122] The first UE may transmit a PSSCH (eg, a 2nd-stage SCI, a MAC protocol data unit (PDU), data, etc.) associated with the PSCCH to the second UE (S8020).

[0123] The first UE may receive a PSFCH associated with the PSCCH / PSSCH from the second UE (S8030). For example, HARQ feedback information (e.g., NACK information or ACK information) may be received from the second UE on the PSFCH.

[0124] The first UE may transmit / report HARQ feedback information to the base station on a PUCCH or a PUSCH (S8040). For example, the HARQ feedback information reported to the base station may be information generated by the first UE based on HARQ feedback information received from the second UE. For example, the HARQ feedback information reported to the base station may be information generated by the first UE based on a pre-configured rule. For example, the DCI may be DCI for SL scheduling. For example, the format of the DCI may be DCI format 3_0 or DCI format 3_1.

[0125] Referring to FIG. 7(b), in LTE transmission mode 2, LTE transmission mode 4, or NR resource allocation mode 2, the UE can determine SL transmission resources from SL resources configured by the base station / network or preconfigured SL resources. For example, the configured SL resources or preconfigured SL resources may be a resource pool. For example, the UE can autonomously select or schedule resources for SL transmission. For example, the UE can select resources by itself from a configured resource pool to perform SL communication. For example, the UE can perform sensing and resource (re)selection procedures and select resources by itself within a selection window. For example, the sensing may be performed on a sub-channel basis.

[0126] The first UE that has selected a resource from the resource pool may transmit a PSCCH (eg, an SCI or a 1st-stage SCI) to the second UE using the resource (S8010).

[0127] The first UE may transmit a PSSCH (eg, a 2nd-stage SCI, a MAC PDU, data, etc.) associated with the PSCCH to the second terminal (S8020).

[0128] The first UE may receive a PSFCH associated with the PSCCH / PSSCH from the second UE (S8030).

[0129] 7(a) or 7(b), for example, the first UE may transmit an SCI to the second UE on a PSCCH. Or, for example, the first UE may transmit two consecutive SCIs (e.g., 2-stage SCIs) to the second UE on a PSCCH and / or a PSSCH. In this case, the second UE may decode the two consecutive SCIs (e.g., 2-stage SCIs) to receive the PSSCH from the first UE. In the present disclosure, the SCI transmitted on the PSCCH may be referred to as a first SCI, a first SCI, a first-stage SCI, or a 1st-stage SCI format, and the SCI transmitted on the PSSCH may be referred to as a second SCI, a second SCI, a second-stage SCI, or a 2nd-stage SCI format. For example, the 1st-stage SCI format may include SCI format 1-A, and the 2nd-stage SCI format may include SCI format 2-A and / or SCI format 2-B.

[0130] 7(a) or 7(b), in step S8030, the first UE may receive a PSFCH based on the description to be described later. For example, the first UE may determine a PSFCH resource based on the description to be described later, and the second UE may transmit HARQ feedback to the first UE on the PSFCH resource.

[0131] This document describes the UE procedures for reporting HARQ-ACK on the sidelink as specified in TS 38.213.

[0132] The UE may be instructed by an SCI format that schedules PSSCH reception to transmit a PSFCH including HARQ-ACK information in response to the PSSCH reception. The UE provides HARQ-ACK information including an ACK or a NACK or only a NACK.

[0133] The UE may be provided with the number of slots in a resource pool during a PSFCH transmission occasion resource period by the sl-PSFCH-Period. If the number of slots is 0, the UE's PSFCH transmission is disabled in the resource pool.

[0134] The UE is k mod N PSSCH PSFCH = 0, then slot t' k SL (0≦k <T’ max ) contains the PSFCH transmission opportunity resource, where t' k SL is defined in TS 38.214, and T' max is the number of slots belonging to the resource pool within 10240 msec based on TS 38.214, and N PSSCH PSFCH is provided by sl-PSFCH-Period.

[0135] The UE may be instructed by higher layers not to transmit a PSFCH containing HARQ-ACK information in response to receiving a PSSCH.

[0136] The UE provides HARQ-ACK information in a PSFCH transmission in the resource pool if the UE receives a PSSCH in the resource pool and the HARQ feedback enabled / disabled indicator field in the associated SCI format 2-A / 2-B / 2-C has value 1. The UE transmits the PSFCH in the first slot of the resource pool after the last slot of the PSSCH reception that includes a PSFCH resource and that corresponds to at least a number of slots provided by sl-MinTimeGapPSFCH.

[0137] The UE selects M DMA channels in the resource pool for transmission of the PSFCH including the HARQ-ACK information in the physical resource block (PRB) of the resource pool. PRB,set PSFCH A set of PRBs is provided by sl-PSFCH-RB-Set. The UE selects M PRBs in the resource pool for PSFCH transmission including conflict information in the PRBs of the resource pool. PRB,set PSFCH A set of PRBs may be provided by sl-RB-SetPSFCH. The UE expects that different PRBs are configured (pre-configured) for collision information and HARQ-ACK information. SUBCH Number of subchannels and N PSSCH PSFCH For a number of PSSCH slots associated with the PSFCH slot that is less than or equal to the number of PSSCH slots associated with the PSFCH slot, the UE may select M PRB,set PSFCH PRB to [(i+j N PSSCH PSFCH )·M subch,slot’ PSFCH (i+1+j N PSSCH PSFCH )·M subch,slot PSFCH -1] PRBs are assigned to slot i, where subch,slot PSFCH =M PRB,set PSFCH / (N subch N PSSCH PSFCH ), 0≦i <N PSSCH PSFCH , 0≦j <N subch where the allocation starts with increasing i and continues with increasing j. The UE PRB,set PSFCH is N subch N PSSCH PSFCH is expected to be a multiple of .

[0138] The UE shall determine the number of PSFCH resources available for multiplexing HARQ-ACK or collision information in a PSFCH transmission based on the indication by sl-PSFCH-CandidateResourceType as follows: PRB,CS PSFCH =N type PSFCH M subch,slot PSFCH N CS PSFCH Here, N CS PSFCH is the number of cyclic shift pairs for the resource pool provided by sl-NumMuxCS-Pair.

[0139] - If sl-PSFCH-CandidateResourceType is set to startSubCH, N type PSFCH = 1, and M subch,slot PSFCH This PRB is associated with the starting subchannel of the PSSCH.

[0140] - If sl-PSFCH-CandidateResourceType is set to allocSubCH, N type PSFCH =N subch PSSCH and N subch PSSCH M subch,slot PSFCH PRBs are N subch PSSCH associated with sub-channels.

[0141] - For collision information, the PSSCH is determined based on sl-PSFCH-Occasion.

[0142] The PSFCH resource is N type PSFCH M subch,slot PSFCH PRBs, first in ascending order of PRB index, then N CS PSFCHThe cyclic shift pairs are indexed in ascending order of the cyclic shift pair indexes.

[0143] The UE determines whether the PSFCH resource index for transmitting the PSFCH including HARQ-ACK information or collision information in response to the PSSCH reception is (P ID +M ID )modR PRB,CS PSFCH Here, P ID is a physical layer source ID provided by SCI format 2-A / 2-B / 2-C for scheduling PSSCH reception or reserving resources for collision information provided by other UEs. If the UE detects SCI format 2-A with a cast type indicator field value of '01' for HARQ-ACK information, M ID is the identity of the UE receiving the PSSCH indicated by the higher layer, otherwise, M ID is 0. For collision information, M ID is 0.

[0144] For a PSFCH transmission including HARQ-ACK information or collision information, the UE calculates a cyclic shift value α from the cyclic shift pair index corresponding to the PSFCH resource index using Table 6 below and N CS PSFCH From this, the m0 value is determined.

[0145] Table 6 illustrates a set of cyclic shift pairs.

[0146] [Table 6]

[0147] For a PSFCH transmission including HARQ-ACK information, if the UE detects SCI format 2-A or SCI format 2-C having a cast type indicator field value of '01' or '10', the UE calculates the cyclic shift value α as shown in Table 7 below. cs If the UE detects SCI format 2-B or 2-A having a cast type indicator field value of '11', m is set as shown in Table 8 below. cs For a PSFCH transmission that includes collision information, the UE determines the value of m cs The UE determines a cyclic shift from the cyclic shift pair to a sequence used for PSFCH transmission. Table 7 illustrates a mapping of the cyclic shift of the sequence for PSFCH transmission from the cyclic shift pair to the HARQ-ACK information bit value when the HARQ-ACK information includes an ACK or NACK.

[0148] [Table 7]

[0149] Table 8 illustrates a mapping of cyclic shifts of sequences and HARQ-ACK information bit values ​​for PSFCH transmission from a cyclic shift pair when the HARQ-ACK information includes only NACK.

[0150] [Table 8]

[0151] Table 9 illustrates a mapping from cyclic shift pairs to cyclic shifts of sequences and collision information bit values ​​for PSFCH transmission.

[0152] [Table 9]

[0153] 8 illustrates a cast type for V2X or SL communication in a wireless communication system to which the present disclosure can be applied. The embodiment of FIG. 8 may be combined with various embodiments of the present disclosure.

[0154] Referring to FIG. 8, FIG. 8(a) shows broadcast type SL communication, FIG. 8(b) shows unicast type SL communication, and FIG. 8(c) shows group-cast type SL communication. In the case of unicast type SL communication, a UE can perform one-to-one communication with another UE. In the case of group-cast type SL communication, a UE can perform SL communication with one or more UEs in a group to which the UE belongs. In various embodiments of the present disclosure, the SL group-cast communication can be referred to as SL multicast communication, SL one-to-many communication, etc.

[0155] The Hybrid Automatic Repeat Request (HARQ) procedure will be described below.

[0156] For example, SL HARQ feedback may be enabled for unicast. In this case, in a non-Code Block Group (non-CBG) operation, if a receiving UE decodes a PSCCH targeted to the receiving UE and the receiving UE successfully decodes a transport block associated with the PSCCH, the receiving UE may generate an ACK. The receiving UE may then transmit a HARQ-ACK to the transmitting UE. On the other hand, if the receiving UE decodes a PSCCH targeted to the receiving UE but fails to successfully decode a transport block associated with the PSCCH, the receiving UE may generate a NACK. The receiving UE may then transmit a NACK to the transmitting UE.

[0157] Also, for example, SL HARQ feedback may be enabled for groupcast. For example, in non-CBG operation, two HARQ feedback options may be supported for groupcast.

[0158] (1) Groupcast Option 1: After a receiving UE decodes a PSCCH targeted to the receiving UE, if the receiving UE fails to decode a transport associated with the PSCCH, the receiving UE can send a NACK to the transmitting UE on a PSFCH. On the other hand, if the receiving UE decodes a PSCCH targeted to the receiving UE and the receiving UE successfully decodes a transport block associated with the PSCCH, the receiving UE does not need to send an ACK to the transmitting UE.

[0159] (2) Groupcast Option 2: After a receiving UE decodes a PSCCH targeted to the receiving UE, if the receiving UE fails to decode a transmission block associated with the PSCCH, the receiving UE can send a NACK to the transmitting UE on the PSFCH. And, if the receiving UE decodes a PSCCH targeted to the receiving UE and the receiving UE successfully decodes a transmission block associated with the PSCCH, the receiving UE can send an ACK to the transmitting UE on the PSFCH.

[0160] For example, when groupcast option 1 is used for SL HARQ feedback, all UEs performing groupcast communication can share the PSFCH resource, e.g., UEs belonging to the same group can use the same PSFCH resource to transmit HARQ feedback.

[0161] For example, when groupcast option 2 is used for SL HARQ feedback, each UE performing groupcast communication can use different PSFCH resources for HARQ feedback transmission, for example, UEs belonging to the same group can transmit HARQ feedback using different PSFCH resources.

[0162] In this disclosure, an ACK may be referred to as a HARQ-ACK, ACK information, or positive-ACK information, and a NACK may be referred to as a HARQ-NACK, NACK information, or negative-ACK information.

[0163] The sidelink grant may be configured semi-persistently by the RRC or dynamically received from the PDCCH selected autonomously by the MAC entity, which may have a sidelink grant in the active SL BWP to determine the set of PSCCH periods in which the SCI transmissions occur and the set of PSSCH periods in which the SL-SCH transmissions associated with the SCI occur.

[0164] When the MAC entity is configured in sidelink resource allocation mode 1, it may take action based on each PDCCH opportunity and on each grant received for that PDCCH opportunity.

[0165] Terminal / base station behavior for consecutive LBT failures in SL transmission

[0166] NR Unlicensed Spectrum (NR-U) refers to a mode that provides the technology necessary for cellular operators to integrate unlicensed spectrum into their wireless communication systems. NR-U enables full uplink and downlink operation in unlicensed spectrum.

[0167] In NR-U, uplink and downlink channel access depends on the LBT function. The terminal and / or base station may first sense the communication channel to determine whether there is any communication before transmitting. If the communication channel is a wideband unlicensed carrier, the NR-U channel sensing procedure may rely on sensing energy levels in multiple sub-bands of the communication channel. The base station may configure LBT parameters (e.g., type / duration, clear channel assessment parameters, etc.) for the terminal.

[0168] In NR-U, a terminal can determine when and where to transmit and receive based on the instructions of a channel occupancy time (COT) structure. The COT is composed of multiple slots, and each slot may be composed of a downlink resource, an uplink resource, or a flexible resource.

[0169] In an NR-U system, both contiguous and interlaced uplink resource allocations may be supported while observing regulations. In interlaced uplink resource allocation, the basic unit of resource allocation for NR unlicensed channels may be an interlace. For example, a single interlace may consist of 10 equally spaced resource blocks within a 20 MHz frequency bandwidth for 15 kHz subcarrier spacing.

[0170] For NR-U, the physical layer can perform an LBT procedure. The LBT procedure means that no transmission occurs if the channel is confirmed to be occupied. If the LBT procedure identifies that the channel is occupied, no transmission occurs by the physical layer. If the physical layer performs the LBT procedure before transmission and no transmission occurs, the physical layer can send an LBT failure indication to the MAC entity.

[0171] Unless otherwise specified, when an LBT procedure is performed for a transmission, the operations specified in this disclosure may be performed regardless of whether an LBT failure indication is received from the physical layer. If the physical layer does not perform LBT, an LBT failure indication may not be received from the physical layer.

[0172] When SL transmission is supported in an unlicensed band, the terminal can perform LBT for SL transmission. In this case, LBT failure may occur in SL transmission as well as in UL transmission. When SL mode 2 is configured, the terminal can autonomously (re)select SL resources for SL transmission. In this case, when consecutive LBT failures occur in SL transmission, the basic wireless communication system does not define a method for avoiding LBT failures for SL transmission (e.g., LBT failures for SL transmission when SL mode 2 is configured).

[0173] The following describes the operation of a terminal / base station when consecutive LBT failures occur for SL transmission.

[0174] For convenience of explanation, a sidelink Tx (transmission) terminal is referred to as a first terminal, and a sidelink Rx (reception) terminal is referred to as a second terminal in Fig. 9. Also, in Fig. 9, the sidelink operation between the first terminal and the second terminal can operate in an unlicensed band / spectrum or a shared spectrum.

[0175] FIG. 9 is a diagram illustrating a process in which a first terminal performs communication according to an embodiment of the present disclosure.

[0176] The first terminal may receive configuration information related to a plurality of sidelink (SL) resource pools and / or a plurality of resource block (RB) sets from the base station (S910).

[0177] As an example, the first terminal may receive configuration information related to a plurality of SL pools and configuration information related to a plurality of RB sets from the base station independently, but is not limited to this. The first terminal may receive RRC signaling (e.g., "SL-Resource Pool") including configuration information related to a plurality of SL pools and configuration information related to a plurality of RB sets (e.g., "sl-StartRB-Subchannel" and / or "sl-RB-Number") from the base station.

[0178] Additionally or alternatively, the terminal may receive configuration information related to SL resource allocation mode 2 from the base station via RRC signaling.

[0179] The first terminal may detect and trigger a consistent SL LBT failure for at least one of a first SL resource pool or a first RB set among a plurality of SL resource pools and a plurality of RB sets (S920).

[0180] As an example, the first terminal may (re)start a timer for detecting SL LBT failure. The first terminal may increment an SL LBT counter by 1 each time an SL LBT failure is detected from at least one of the first SL resource pool or the first RB set. If the SL LBT counter value is equal to or greater than the SL LBT instance maximum count value, the first terminal may trigger a consistent SL LBT for at least one of the first SL resource pool or the first RB set.

[0181] Based on the triggered consistent SL LBT not being cancelled, the first terminal may trigger an SL resource reselection to select a second SL resource pool or a second RB set from among the multiple resource pools and the multiple RB sets (S930).

[0182] That is, SL resource reselection may be triggered based on the absence of sidelink transmission (e.g., physical sidelink shared channel (PSSCH) transmission, etc.) due to triggered consistent SL LBT failures.

[0183] Specifically, when the granularity of SL LBT failure is an SL resource pool / RB set, upon detection of a consistent SL LBT failure, a change of the SL resource pool / RB set that does not trigger a consistent SL LBT failure upon consistent SL LBT failure by the first terminal may be supported.

[0184] Additionally or alternatively, based on the consistent SL LBT failure being triggered / detected in the first SL BWP or / and first cell, SL resource reselection may be triggered in the second SL BWP or / and second cell to generate a new selected SL grant (e.g., a third selected SL grant).

[0185] As an example of the present disclosure, a second SL resource pool may be selected from among the multiple resource pools based on the consistent SL LBT being triggered a first number of times, and a second RB set may be selected from among the multiple RB sets based on the consistent SL LBT being triggered a second number of times, where the first number of times may be greater than or less than the second number of times. That is, SL resource reselection may perform RB set or SL resource pool reselection based on the consistent SL LBT detection / triggering number of times.

[0186] Additionally or alternatively, the entire selected sidelink grant may be reselected based on N1 (consistent) SL LBT failures being detected / triggered. As an example, a new sidelink grant may be selected from among the existing SL resource pool / RB set. Based on N2 (consistent) SL LBT failures being detected / triggered, resource pool reselection may be performed. And based on N3 (consistent) SL LBT failures being detected / triggered, RB set / SL BWP / cell reselection may be performed.

[0187] At this time, a selected SL grant corresponding to at least one of the first SL resource pool or the first RB set may be removed, but is not limited thereto.

[0188] Then, a second selected sidelink grant is generated based on at least one of the second SL resource pool and / or the second RB set, and the first terminal may perform SL LBT based on the second selected sidelink grant. The first terminal may transmit a MAC PDU to the second terminal according to a result of the SL LBT.

[0189] As an example of the present disclosure, a triggered consistent SL LBT may be cancelled based on configuration information related to a failure recovery procedure being reconfigured by the base station.

[0190] An SL LBT counter value for determining whether to trigger a consistent SL LBT may be set to 0 based on the triggered consistent SL LBT being canceled or the expiration of a timer associated with the detection of a consistent SL LBT.

[0191] The method performed by the first terminal described in the example of FIG. 9 may be performed by the first device 100 of FIG.

[0192] For example, the one or more processors 102 of the first device 100 of FIG. 13 may be configured to receive configuration information related to a plurality of SL resource pools and a plurality of RB sets from a base station (e.g., the second device 200) via the one or more transceivers 106. The one or more processors 102 may be configured to trigger a consistent SL LBT for at least one of a first SL resource pool or a first RB set among the plurality of SL resource pools and the plurality of RB sets. The one or more processors 102 may be configured to trigger an SL resource reselection to select a second SL resource pool or a second RB set from among the plurality of resource pools and the plurality of RB sets based on the triggered consistent SL LBT failure not being cancelled.

[0193] It should be noted that the one or more memories 104 of the first device 100 may store instructions for performing the method described in the example of FIG. 9 when executed by the one or more processors 102 .

[0194] FIG. 10 is a diagram for explaining a process in which a base station according to an embodiment of the present disclosure performs communication.

[0195] The base station may transmit configuration information related to a plurality of SL resource pools and a plurality of RB sets to the first terminal by RRC signaling (S1010). The configuration information transmitted by the base station to the first terminal has been described with reference to FIG. 9, and the duplicated description will be omitted.

[0196] The base station may receive, from the first terminal, a MAC CE associated with consistent SL LBT failures for at least one of a first SL resource pool or a first RB set among the multiple SL resource pools and the multiple RB sets (S1020).

[0197] Here, the MAC CE associated with the consistent SL LBT failure (eg, a (SL)LBT failure MAC CE) may include information for reporting a triggered SL LBT.

[0198] The method performed by the base station described in the example of FIG. 10 may be performed by the second device 200 of FIG.

[0199] 13 may be configured to send configuration information related to the multiple SL resource pools and the multiple RB sets to the first terminal via the one or more transceivers 106. The one or more processors 102 may be configured to receive from the first terminal via the one or more transceivers 106 a MAC CE associated with consistent SL LBT failures for at least one of a first SL resource pool or a first RB set among the multiple SL resource pools and the multiple RB sets.

[0200] Additionally, the one or more memories 204 of the second device 200 may store instructions for performing the method described in the example of FIG. 10 when executed by the one or more processors 202 .

[0201] FIG. 11 is a diagram illustrating a method for performing resource reselection for a sidelink based on an LBT failure according to one embodiment of the present disclosure.

[0202] The example of Fig. 11 is for convenience of explanation and does not limit the scope of the present disclosure. Some steps illustrated in Fig. 11 may be omitted depending on the situation and / or setting. Also, in Fig. 11, the Tx terminal / Rx terminal / base station are merely examples and may be embodied by the device illustrated in Fig. 13.

[0203] For example, the processor 102 / 202 in Fig. 13 can control the transceiver 106 / 206 to transmit and receive channels / signals / data / information, etc. Also, the processor 102 / 202 in Fig. 13 can control the memory 104 / 204 to store the transmitted channels / signals / data / information, etc., and can also control the memory 104 / 204 to store the received channels / signals / data / information, etc.

[0204] The network (or base station) may transmit sidelink configuration information to a transmitting terminal (i.e., a Tx terminal) by system information and / or terminal-specific RRC signaling (S1110).

[0205] When sidelink configuration information is received from the network, one or more carriers and one or more resource pools may be configured for each carrier for at least one of sidelink resource allocation mode 1 or mode 2 for the Tx terminal.

[0206] Here, the number of HARQ processes may be configured based on a respective resource pool on each carrier. The resource pool may be used for uplink or sidelink transmission. Each resource pool may be associated with a pool index. The maximum number of HARQ processes for each resource pool may be configured. The number of HARQ retransmissions may correspond to the respective number of HARQ processes and / or the SL RSRP or DL ​​RSRP measured by the (Tx) UE.

[0207] In the Tx terminal, the RRC can configure the sidelink resource allocation mode 2 for the MAC entity and transmit using a resource pool of carriers based on sense or random selection, and the MAC entity (in the Tx terminal) can perform each sidelink process.

[0208] In step S1120, the (Tx) terminal checks the transmission resource (re)selection, (re)selects a transmission resource for generation of the selected sidelink grant, performs a channel access procedure with LBT type 1 or 2, and can generate a new MAC PDU for the selected sidelink grant within the COT interval.

[0209] if the MAC entity (at the Tx terminal) has chosen to generate a selected sidelink grant corresponding to the transmission of multiple MAC PDUs and SL data is available on the logical channel; or

[0210] the MAC entity selects to generate a selected sidelink grant corresponding to the transmission of a single MAC PDU, if SL data is available on the logical channel or a SL-CSI report is triggered;

[0211] If the MAC entity has not selected an allowed resource pool for a logical channel:

[0212] - if "sl-HARQ-FeedbackEnabled" is configured as active for a logical channel, the (Tx) terminal selects a PSFCH resource from the resource pool and a configured resource pool;

[0213] - If "sl-HARQ-FeedbackEnabled" is not configured as active for a logical channel, the (Tx) terminal can select a specific resource pool from among the resource pools.

[0214] In the (Tx) terminal, when the MAC entity selects a new resource pool as described above or when the MAC entity triggers a Tx resource (re)selection, the MAC entity can perform a TX resource (re)selection to generate the selected sidelink grant for the selected resource pool according to the below described scheme of transmission resource (re)selection.

[0215] - The MAC entity selects one of the allowed values ​​configured by RRC in "sl-ResourceReservePeriodList" and sets the selected value as the resource reservation interval (P rsvp_TX ) can be set as;

[0216] - The MAC entity shall select from the interval [5,15] if the resource reservation interval is greater than or equal to 100 ms, and from the interval [5,15] if the resource reservation interval is less than 100 ms. We can arbitrarily choose an integer value from JPEG2025514210000018.jpg1682 with equal probability and set the chosen value for "SL_RESOURCE_RESELECTION_COUNTER";

[0217] - the MAC entity selects the number of HARQ retransmissions from the allowed number configured by RRC in "sl-MaxTxTransNumPSSCH" included in "sl-PSSCH-TxConfigList" and when configured by RRC, it may overlap between "sl-MaxTxTransNumPSSCH" indicated in "sl-CBR-PriorityTxConfigList" and the CBR measured by lower layers for the highest priority of the logical channel allowed on the carrier if the CBR measurement result is available, or the corresponding "sl-defaultTxConfigIndex" configured by RRC if the CBR measurement result is not available;

[0218] - The MAC entity shall select the amount of frequency resources within the range set by RRC among 'sl-MinSubChannelNumPSSCH' and 'sl-MaxSubchannelNumPSSCH' included in 'sl-PSSCH-TxConfigList', and when configured by RRC, if there is a CBR measurement result, it may overlap between 'MinSubChannelNumPSSCH' and 'MaxSubchannelNumPSSCH' indicated in 'sl-CBR-PriorityTxConfigList' and the CBR measured by lower layers for the highest priority logical channel allowed on the carrier, or overlap with the corresponding 'sl-defaultTxConfigIndex' set by RRC if the CBR measurement result is not available.

[0219] - the MAC entity may arbitrarily select time and frequency resources for one transmission opportunity from among the resources indicated by the physical layer depending on the amount of selected frequency resources and the remaining PDB of SL data available for the allowed logical channels on the carrier;

[0220] - the MAC entity may use randomly selected resources to select a set of consecutive resources for the transmission of PSCCH and PSSCH corresponding to multiple transmission opportunities of multiple MAC PDUs or one or multiple transmission opportunities of a single MAC PDU;

[0221] - If one or more HARQ retransmissions are selected and there are still available resources in the resources indicated by the physical layer for more transmission opportunities:

[0222] The MAC entity may randomly select time and frequency resources for one or more transmission opportunities from the resources available according to the remaining PDB of SL data available for the allowed logical channels on the carrier, guaranteeing the amount of selected frequency resources, the number of selected HARQ retransmissions, and the minimum time interval between two selected resources. This may be done if a PSFCH is configured for the resource pool and the retransmission resources may be indicated by the time resource allocation of a previous SCI;

[0223] - the MAC entity may select periodic resource sets spaced apart by a resource reservation interval for PSCCH and PSSCH transmissions corresponding to the determined number of retransmission opportunities for the MAC PDU using the randomly selected resources;

[0224] - the MAC entity may consider the first set of transmission opportunities as initial transmission opportunities and the other sets of transmission opportunities as retransmission opportunities;

[0225] - The MAC entity may consider the set of initial transmission and retransmission opportunities as the selected sidelink grant.

[0226] If one or more HARQ retransmissions are not selected, the MAC entity may consider the set as the selected sidelink grant.

[0227] The MAC entity may use the selected sidelink grant to determine a set of PSCCH durations and a set of PSSCH durations.

[0228] Alternatively, in the Tx terminal, when the MAC entity selects a new resource pool or when the MAC entity triggers a TX resource (re)selection, the MAC entity can perform a TX resource (re)selection to generate the selected sidelink grant for the selected resource pool according to the following scheme for Tx resource (re)selection:

[0229] - The MAC entity shall select the number of HARQ retransmissions from the allowed number set by RRC in 'sl-MaxTxTransNumPSSCH' contained in 'sl-PSSCH-TxConfigList' and, when set by RRC, may overlap between 'sl-MaxTxTransNumPSSCH' indicated in 'sl-CBR-PriorityTxConfigList' and the CBR measured by lower layers for the highest priority of logical channels allowed on the carrier if CBR measurements are available, or with the corresponding 'sl-defaultTxConfigIndex' set by RRC if CBR measurements are not available.

[0230] - the MAC entity selects the amount of frequency resources within the RRC configured range of 'sl-MinSubChannelNumPSSCH' and 'sl-MaxSubchannelNumPSSCH' included in 'sl-PSSCH-TxConfigList', which when configured by RRC may overlap between 'MinSubChannelNumPSSCH' and 'MaxSubchannelNumPSSCH' indicated in 'sl-CBR-PriorityTxConfigList' and the CBR measured by lower layers for the highest priority of logical channels allowed on the carrier if CBR measurement results are available, and the corresponding 'sl-defaultTxConfigIndex' configured by RRC if CBR measurement results are not available;

[0231] - The MAC entity may arbitrarily select time and frequency resources for one transmission opportunity from the resources indicated by the physical layer depending on the amount of selected frequency resources and the remaining PDB of SL data available for the allowed logical channels on the carrier.

[0232] The MAC entity may use randomly selected resources to select a set of contiguous resources for PSCCH and PSSCH transmission that correspond to multiple transmission opportunities for multiple MAC PDUs or one or multiple transmission opportunities for a single MAC PDU.

[0233] For transmission of the PSCCH and PSSCH corresponding to one of the multiple transmission opportunities of multiple MAC PDUs, the MAC entity may periodically select a set of consecutive resources based on a resource reservation interval.

[0234] Here, one of the allowed values ​​set by RRC in "sl-ResourceReservePeriodList" may be selected as the resource reservation interval. A set of contiguous resources may be reserved for each resource reservation interval.

[0235] One or more HARQ processes may be assigned to one contiguous resource set in each resource reservation interval, and the number of HARQ processes may be determined by a (maximum or fixed) number of HARQ processes for each contiguous resource set or each resource reservation interval.

[0236] The (maximum or fixed) number of HARQ processes for each contiguous resource set or each resource reservation interval may be configured by the base station or may be pre-configured / defined.

[0237] The (maximum or fixed) number of HARQ processes may be (pre-)configured per resource pool, per SL BWP, per serving cell, per selected sidelink grant or per logical channel priority of the SL logical channel used to trigger resource selection.

[0238] For one or more HARQ process IDs indicated to one or more SCIs for each consecutive resource set or resource reservation interval, different SCIs may indicate the same or different HARQ process IDs as described below to schedule different PSSCH transmissions for the same TB or different TBs.

[0239] For multiple TBs transmitted to the same destination terminal, the terminal may assign different HARQ process IDs to different HARQ processes for each consecutive resource set or resource reservation interval.

[0240] When multiple TBs are transmitted to different destination UEs, the UE may assign the same or different HARQ process IDs to different HARQ processes for each consecutive resource set or resource reservation interval.

[0241] One or more PSFCH resources may be reserved for each contiguous resource set or resource reservation interval.

[0242] - Option 1: One or more PSFCH resources in a resource reservation interval may be used to send one or more HARQ-ACKs on a series of consecutive PSSCH resources, always in the same resource reservation interval.

[0243] - Option 2: One or more PSFCH resources in a resource reservation interval may be used to transmit one or more HARQ-ACKs on a series of consecutive PSSCH resources in a previous resource reservation interval.

[0244] Other PSFCH resources of the resource reservation interval may be used to transmit one or more HARQ-ACKs on consecutive PSSCH resource sets in the same resource reservation interval.

[0245] The MAC entity may consider this set as a selected sidelink grant, which the MAC entity may use to determine the PSCCH period set and the PSSCH period set.

[0246] Thereafter, in a step to be described later, the terminal can perform SL transmission on the selected sidelink grant using the PSCCH duration set and the PSSCH duration set.

[0247] At S1130, the Tx terminal may perform a sidelink (re)transmission of the MAC PDU on the selected resources and receive a SL ACK / NACK on the PSFCH, where the Tx terminal may (re)select Tx resources or reserve additional resources for the retransmission of the MAC PDU if the SL NACK is received on the PSFCH.

[0248] A consistent (or continuous) LBT failure recovery procedure may be configured by the RRC for the MAC entity of the (Tx) terminal. If the physical layer of the terminal fails to access the channel before an intended UL or SL transmission to the base station, the physical layer may inform the MAC layer of a channel access failure (i.e., an LBT failure).

[0249] The terminal can sense / detect consistent (or consecutive) LBT failures per SL BWP, per UL BWP, or per serving cell by counting LBT failure indications for all SL transmissions and / or all UL transmissions from the physical layer to the MAC entity based on at least one of the embodiments described below (S1140).

[0250] The Tx terminal may transmit a PUCCH for SR to the base station (S1150). The Tx terminal may trigger a transmission resource (re)selection based on the consistent LBT failures (S1160). The Tx terminal may perform a sidelink retransmission of the MAC PDU on the (re)selected resources (S1170).

[0251] The above-mentioned operation of the Tx terminal will be specifically explained below.

[0252] Example 1: Integrated UL / SL LBT failure detection and recovery procedure

[0253] The terminal may count LBT_COUNTER based on LBT failures for both UL transmissions using UL BWP and SL transmissions using SL BWP for each serving cell. An LBT failure MAC CE may be generated and shared for LBT failures in both UL and SL. A scheduling request (SR) may be triggered and shared for LBT failures in both UL and SL. SR configuration and resources may be common for both UL LBT failure reporting and SL LBT failure reporting. Parameters of 'lbt-FailureRecoveryConfig' (e.g., 'lbt-FailureInstanceMaxCount' and 'lbt-FailureDetectionTimer') may be shared between UL and SL and may be configured by RRC.

[0254] A consistent LBT failure recovery procedure may be configured by the RRC for the MAC entity of the terminal. A consistent LBT failure may be detected by counting LBT failure indications for all UL transmissions and / or all SL transmissions from the lower layer (i.e., physical layer) to the MAC entity per UL BWP, per SL BWP, or per BWP where the UL BWP and the SL BWP overlap.

[0255] LBT_COUNTER (per serving cell) may be used for consistent LBT failure detection procedure. The LBT_COUNTER is a counter for LBT failure indication that is initially set to 0. For each serving cell, the LBT_COUNTER may be used to count LBT failure indications for UL transmission only for the UL BWP of the serving cell, or to count LBT failure indications for SL transmission only for the SL BWP of the serving cell, or to count both LBT failure indications for UL transmission and LBT failure indications for SL transmission for both UL BWP and SL BWP of the serving cell.

[0256] For each activated serving cell configured in "lbt-FailureRecoveryConfig", the terminal's MAC entity may perform the following actions:

[0257] 1> If an LBT failure indication is received from lower layers for UL or SL transmission:

[0258] 2>Start or restart lbt-FailureDetectionTimer;

[0259] 2>Increase LBT_COUNTER by 1;

[0260] 2>If LBT_COUNTER>=lbt-FailureInstanceMaxCount:

[0261] 3> Trigger consistent LBT failures for active UL BWPs in that serving cell;

[0262] 3> Trigger consistent LBT failures for active SL BWPs in that serving cell;

[0263] 3> If the serving cell is an SpCell:

[0264] 4> Consistent LBT failures are triggered on all UL BWPs configured with PRACH opportunities on the same carrier of the serving cell; or

[0265] 4> If a consistent LBT failure is triggered in the SL BWP and a PRACH opportunity is set to a UL BWP of the same carrier of the SL BWP in the serving cell:

[0266] 5> Indicate a consistent LBT failure to higher layers (i.e., the RRC layer).

[0267] 4>If not:

[0268] 5> Abort any ongoing random access procedure in that serving cell;

[0269] 5> Switch the active UL BWP to the (target) UL BWP on the same carrier of the serving cell that is configured as a PRACH opportunity and has not triggered a consistent LBT failure;

[0270] 5> Convert an active SL BWP to a (target) SL BWP on the same carrier of the serving cell for which no consistent LBT failure has been triggered, where the target SL BWP is associated with or overlaps with the target UL BWP.

[0271] 5> Initiate random access procedure.

[0272] 1> All triggered consistent LBT failures are cancelled in the serving cell; or

[0273] 1> The lbt-FailureDetectionTimer expires; or

[0274] 1> When lbt-FailureDetectionTimer or lbt-FailureInstanceMaxCount is reset by a higher layer:

[0275] 2>Set LBT_COUNTER to 0.

[0276] The MAC entity of the terminal is:

[0277] 1> A consistent LBT failure is triggered in the SpCell and is not cancelled; and

[0278] 1> If UL-SCH resources are available for a new transmission in the SpCell and the UL-SCH resources can accommodate the LBT failed MAC CE and the subheader as a result of logical channel priority:

[0279] 2> Instruct the multiplexing and assembly procedure to generate an LBT failure MAC CE.

[0280] 1> If a consistent LBT failure has been triggered on at least one SCell and has not been cancelled:

[0281] 2> If UL-SCH resources are available for new transmission in a serving cell where no consistent LBT failures have been triggered and the UL-SCH resources can accommodate the LBT failed MAC CE and the subheader as a result of logical channel priority:

[0282] 3> Instruct the multiplexing and assembly procedure to generate an LBT failure MAC CE.

[0283] 2>If not:

[0284] 3>LBT failure Trigger a scheduling request for the MAC CE.

[0285] 1> If a MAC PDU is sent, no LBT failure indication is received from the lower layer, and the PDU contains an LBT failure MAC CE:

[0286] 2> Cancel all consistent LBT failures triggered on the SCell for which consistent LBT failure was indicated in the transmitted LBT failure MAC CE.

[0287] 1> Consistent LBT failures are triggered and not cancelled in the SpCell; and

[0288] 1> The random access procedure is considered to be successfully completed in the SpCell:

[0289] 2> Cancel all consistent LBT errors triggered by SpCell.

[0290] 1> When lbt-FailureRecoveryConfig is reconfigured by higher layers for the serving cell:

[0291] 2> Cancel all consistent LBT failures triggered in that serving cell.

[0292] Example 1-1

[0293] Example 1-1 relates to an LBT failure MAC CE for Example 1.

[0294] The 1-octet LBT failure MAC CE may be identified by a MAC subheader with a specific LCID (e.g., an LCID mapped to 43 or / and 49 index / codepoints). As shown in Figure 12(a), the size of the 1-octet LBT failure MAC CE is fixed and may consist of a single octet containing 8 C fields.

[0295] The 4-octet LBT failure MAC CE may be identified by a MAC subheader with a specific LCID (e.g., an LCID that maps to 42 or / and 48 index / codepoints). As shown in FIG. 12(b), the size of the 4-octet LBT failure MAC CE is fixed and may consist of 4 octets including a 32-bit C field.

[0296] If the highest "ServCellIndex" of the serving cell of the MAC entity for which an LBT failure is detected is less than 8, the single octet format may be used, otherwise the four octet format may be used.

[0297] In (a) and (b) of FIG. 12, if there is a serving cell configured for a MAC entity with “ServCellIndex” i, and a consistent LBT failure across UL and SL has been triggered, and the consistent LBT failure has not been revoked in the serving cell, C i may be set to 1. Otherwise, C i may be set to 0.

[0298] Example 2: SL-specific LBT failure detection and recovery procedure

[0299] That is, embodiment 2 relates to separate LBT failure detection and recovery procedures for SL LBT failure and UL LBT failure, and possible interactions between SL LBT failure and UL LBT failure.

[0300] For each serving cell, the terminal can separately count the existing LBT_COUNTER based on LBT failure for UL transmission in the UL BWP and the new LBT_COUNTER_SL based on LBT failure for SL transmission in the SL BWP.

[0301] An existing LBT failure MAC CE and a new LBT failure MAC CE may be generated separately for UL LBT failure and SL LBT failure, respectively. An SR for UL LBT failure and an SR for SL LBT failure may be triggered separately. SR configuration and resources may be configured and allocated separately for reporting UL LBT failure and SL LBT failure.

[0302] The parameters of 'lbt-FailureRecoveryConfig' (eg, 'lbt-FailureInstanceMaxCount' and 'lbt-FailureDetectionTimer') may be set by RRC separately for UL LBT failure and SL LBT failure, respectively.

[0303] Additionally or alternatively, as embodiment 2, the existing LBT failure MAC CE may be reused for SL LBT failure reporting and UL LBT failure reporting, i.e., the same MAC CE format may be used to indicate SL LBT failure or UL LBT failure based on other LC (logical channel) ID values.

[0304] The parameters of "lbt-FailureRecoveryConfig" (e.g., "lbt-FailureInstanceMaxCount" and "lbt-FailureDetectionTimer") may be reused for SL LBT failure detection and UL LBT failure detection. That is, "lbt-FailureInstanceMaxCount" or "lbt-FailureDetectionTimer" can operate based on the same parameter setting in "lbt-FailureRecoveryConfig".

[0305] Here, the SR configuration and resources may be common to both UL LBT failure reporting and SL LBT failure reporting.

[0306] Since the BWP may be configured with one or more RB sets (i.e., 20 MHz LBT bandwidth) on which the UE performs LBT, the UE may perform LBT failure detection and recovery procedures for each SL or UL specific RB set instead of the SL BWP or UL BWP. In this case, the BWP may be replaced with the RBs configured in each embodiment.

[0307] The MAC entity of the terminal may be configured by the RRC with a consistent LBT failure recovery procedure. Consistent LBT failure may be detected by counting LBT failure indications for all UL transmissions or all SL transmissions from lower layers to the MAC entity, per UL BWP, per SL BWP, or per BWP that overlaps with the UL BWP and the SL BWP.

[0308] RRC can set the following parameters in "lbt-FailureRecoveryConfig" for UL LBT failure detection.

[0309] - lbt-FailureInstanceMaxCount for consistent LBT failure detection in UL

[0310] - lbt-FailureDetectionTimer for consistent LBT failure detection in UL

[0311] RRC can configure the following parameters in "lbt-FailureRecoveryConfigSL" for SL LBT failure detection:

[0312] - 'lbt-FailureInstanceMaxCountSL' for consistent LBT failure detection in SL

[0313] - "lbt-FailureDetectionTimerSL" for consistent LBT failure detection in SL

[0314] The following terminal parameters may be used for a consistent LBT failure detection procedure for a UL LBT failure.

[0315] - LBT_COUNTER (per serving cell): A counter for LBT failure indication that is initially set to 0 for UL

[0316] The following terminal parameters may be used for a consistent LBT failure detection procedure for SL LBT failure.

[0317] - LBT_COUNTER_SL (per serving cell): Counter for LBT failure indication, initially set to 0 for SL

[0318] For each activated serving cell configured in "lbt-FailureRecoveryConfig", the terminal's MAC entity can detect UL LBT failure:

[0319] 1> If an LBT failure indication is received from lower layers for UL transmission:

[0320] 2>Start or restart lbt-FailureDetectionTimer;

[0321] 2>Increase LBT_COUNTER by 1;

[0322] 2>If LBT_COUNTER>=lbt-FailureInstanceMaxCount:

[0323] 3> Trigger consistent LBT failures for active UL BWPs in that serving cell;

[0324] 3> If the serving cell is an SpCell:

[0325] 4> If consistent LBT failures are triggered for all UL BWPs configured with PRACH opportunities on the same carrier of the serving cell:

[0326] 5> Indicate a consistent LBT failure to higher layers (i.e., the RRC layer).

[0327] 4>If not:

[0328] 5> Abort any ongoing voluntary access procedure in that serving cell;

[0329] 5> Switch the active UL BWP to the (target) UL BWP on the same carrier of the serving cell that is configured as a PRACH opportunity and has not triggered a consistent LBT failure;

[0330] 5> Convert an active SL BWP to a (target) SL BWP on the same carrier of the serving cell for which no consistent LBT failure has been triggered, where the target SL BWP is associated with or overlaps with the target UL BWP;

[0331] 5> Initiate the random access procedure.

[0332] 1> LBT_COUNTER_SL is set to 0 for SL LBT failure; or

[0333] 1> All consistent LBT failures triggered by SL transmissions are cancelled in the serving cell; or

[0334] 1> lbt-FailureDetectionTimerSL expires; or

[0335] 1> When lbt-FailureDetectionTimerSL or lbt-FailureInstanceMaxCountSL is reset by a higher layer; or

[0336] 1> All consistent LBT failures that have been triggered are cancelled in the serving cell; or

[0337] 1> The lbt-FailureDetectionTimer expires; or

[0338] 1> When lbt-FailureDetectionTimer or lbt-FailureInstanceMaxCount is reset by a higher layer:

[0339] 2>Set LBT_COUNTER to 0.

[0340] For each activated serving cell configured in lbt-FailureRecoveryConfigSL, the UE's MAC entity can detect SL LBT failure.

[0341] 1> If an LBT failure indication is received from the lower layer for SL transmission:

[0342] 2>Start or restart lbt-FailureDetectionTimerSL;

[0343] 2>Increase LBT_COUNTER_SL by 1;

[0344] 2>LBT_COUNTER_SL>=lbt-FailureInstanceMaxCountSL:

[0345] 3> Trigger consistent LBT failures for active SL BWPs in that serving cell;

[0346] 3> If the serving cell is an SpCell:

[0347] 4> If consistent LBT failures are triggered for all SL BWPs and the PRACH opportunity is configured for a UL BWP of the same carrier of the SL BWP in the serving cell:

[0348] 5> Indicate a consistent LBT failure to higher layers (i.e., the RRC layer).

[0349] 4> else;

[0350] 5> Abort any ongoing voluntary access procedure in that serving cell;

[0351] 5> A UL BWP is configured for the PRACH opportunity and converts an active SL BWP to a (target) SL BWP on the same carrier of the serving cell where no consistent LBT failure has been triggered in UL or SL.

[0352] 5> Convert an active UL BWP on the same carrier of the serving cell for which no consistent LBT failure has been triggered to a (target) UL BWP, where the target UL BWP is associated with or overlaps with the target SL BWP;

[0353] 5> Initiate random access procedure.

[0354] 1> LBT_COUNTER is set to 0 for UL LBT failure; or

[0355] 1> The lbt-FailureDetectionTimer expires for a UL LBT failure; or

[0356] 1> When lbt-FailureDetectionTimer or lbt-FailureInstanceMaxCount is reset by higher layers for UL LBT failure;

[0357] 1> All consistent LBT failures triggered by UL transmissions are cancelled in the serving cell; or

[0358] 1> All consistent LBT failures triggered by SL transmissions are cancelled in the serving cell; or

[0359] 1> lbt-FailureDetectionTimerSL expires; or

[0360] 1> When lbt-FailureDetectionTimerSL or lbt-FailureInstanceMaxCountSL is reset by a higher layer:

[0361] 2>Set LBT_COUNTER_SL to 0.

[0362] For UL LBT failure reporting, the MAC entity of the terminal may perform the following actions:

[0363] 1> A consistent LBT failure has been triggered for UL in the SpCell and has not been cancelled; and

[0364] 1> If UL-SCH resources are available for new transmission in the SpCell and such UL-SCH resources can accommodate the LBT failed MAC CE and the subheader in question as a result of logical channel priority:

[0365] 2> Instruct the multiplexing and assembly procedure to generate an LBT failure MAC CE.

[0366] 1> If at least one SCell has a consistent LBT failure triggered for UL and has not been cancelled:

[0367] 2> If UL-SCH resources are available for a new transmission in a serving cell where no consistent LBT failure has been triggered for UL or SL and the UL-SCH resources can accommodate the LBT failure MAC CE and the subheader as a result of logical channel prioritization:

[0368] 3> Instruct the multiplexing and assembly procedure to generate an LBT failure MAC CE.

[0369] 2>If not:

[0370] 3>LBT failure Trigger a scheduling request for the MAC CE.

[0371] 1> If a MAC PDU is sent, no LBT failure indication is received from the lower layer, and the PDU contains an LBT failure MAC CE:

[0372] 2> Cancel all consistent LBT failures triggered on the SCell where consistent LBT failure was indicated on the transmitted LBT failure MAC CE.

[0373] 1> A consistent LBT failure is triggered for the UL and is not cancelled in the SpCell; and

[0374] 1> The random access procedure is considered to be successfully completed in the SpCell:

[0375] 2>(Alt 1-1) Cancel all consistent LBT failures triggered for UL except SL in SpCell.

[0376] 2>(Alt 1-2) Cancel all consistent LBT failures triggered for both UL and SL in SpCell.

[0377] 1> When lbt-FailureRecoveryConfig is reconfigured by higher layers for the serving cell:

[0378] 2> Cancel all consistent LBT failures triggered for UL in that serving cell.

[0379] 2> Cancel all consistent LBT failures triggered for SL in that serving cell.

[0380] For SL LBT failure reporting, the MAC entity of the terminal may perform the following operations:

[0381] 1> A consistent LBT failure has been triggered for SL in SpCell and has not been cancelled; and

[0382] 1> If UL-SCH resources are available for a new transmission in the SpCell and the UL-SCH resources can accommodate the SL LBT failed MAC CE and the subheader as a result of logical channel prioritization:

[0383] 2> Instruct the multiplexing and assembly procedure to generate a SL LBT failure MAC CE

[0384] 1> If a consistent LBT failure has been triggered for SL on at least one SCell and has not been cancelled:

[0385] 2> UL-SCH resources are available for a new transmission in a serving cell where no consistent LBT failure has been triggered for UL or SL, and the UL-SCH resources can accommodate the SL LBT failure MAC CE and the subheader as a result of logical channel priority assignment;

[0386] 3> Instruct the multiplexing and assembly procedure to generate the SL LBT failure MAC CE.

[0387] 2>If not:

[0388] 3>SL LBT failure Trigger a scheduling request to the MAC CE.

[0389] 1> If a MAC PDU is sent, no SL LBT failure indication has been received from the lower layer, and the PDU contains a SL LBT failure MAC CE:

[0390] 2> Cancel all consistent LBT failures triggered on the SCell where consistent LBT failure was indicated on the transmitted LBT failure MAC CE.

[0391] 1> A consistent LBT failure is triggered for the SL and is not cancelled in the SpCell; and

[0392] 1> The random access procedure is considered to be successfully completed in the SpCell:

[0393] 2>(Alt 2-1) Cancel all consistent LBT failures triggered for SL except UL in SpCell.

[0394] 2>(Alt 2-2) Cancel all consistent LBT failures triggered for both UL and SL in SpCell.

[0395] 1> When lbt-FailureRecoveryConfigSL is reconfigured by higher layers for the serving cell:

[0396] 2> All consistent LBT failures triggered for SL in that serving cell can be cancelled.

[0397] 2> All consistent LBT failures triggered for UL in the serving cell can be cancelled.

[0398] Example 2-1

[0399] Example 2-1 relates to an LBT failure MAC CE and a SL LBT failure MAC CE for Example 1.

[0400] The 1-octet LBT failure MAC CE and the SL LBT failure MAC CE may be identified by a MAC subheader with a specific LCID. As shown in (a) of Figure 12, the size of the 1-octet LBT failure MAC CE is fixed and may consist of a single octet containing 8 C fields.

[0401] The 4-octet LBT failure MAC CE and the SL LBT failure MAC CE may be identified by a MAC subheader having a specific LCID. As shown in FIG. 12(b), the size of the 4-octet LBT failure MAC CE is fixed and may consist of 4 octets including 32 C fields.

[0402] The UCID values ​​for the UL-SCH may be defined as shown in Table 10 below.

[0403] [Table 10]

[0404] If the highest "ServCellIndex" of the serving cell of the MAC entity for which an LBT failure is detected is less than 8, the single octet format may be used, otherwise the four octet format may be used. In (a) and (b) of FIG. 12, if there is a serving cell configured for the MAC entity with "ServCellIndex" i, and a consistent LBT failure across UL and SL has been triggered across UL and SL, and the consistent LBT failure has not been revoked in the serving cell, then C i may be set to 1. Otherwise, C i may be set to 0.

[0405] Which embodiment, Example 1 or Example 2, is used may vary depending on the SL mode or the serving cell in which SL transmission is performed. For example, Example 1 may be used for SL mode 1, and Example 2 may be used for SL mode 2. Example 1 may be used for a serving cell in which both UL and SL transmission are permitted, and Example 2 may be used for a serving cell. In this case, only SL transmission may be permitted, and UL transmission may not be permitted.

[0406] Example 3

[0407] The third embodiment relates to the operation of the Tx terminal subsequent to the first embodiment and / or the second embodiment.

[0408] If the selected sidelink grant is available for the retransmission of a positively acknowledged MAC PDU in the Tx UE, the UE may clear the PSCCH and PSSCH periods corresponding to the retransmission of the MAC PDU in the selected sidelink grant, where the selected sidelink grant may correspond to the transmission of a single MAC PDU or the transmission of multiple MAC PDUs.

[0409] In the Tx terminal, the MAC entity may continue to perform the Tx resource (re)selection confirmation procedure until either the resource pool is released by RRC or the MAC entity decides to cancel the generation of the selected sidelink grant corresponding to the transmission of multiple MAC PDUs or the transmission of a single MAC PDU.

[0410] The MAC entity may perform a Tx resource (re)selection check in the selected resource pool for this sidelink process if one or more of the following conditions are met:

[0411] - if SL_RESOURCE_RESELECTION_COUNTER=0 and SL_RESOURCE_RESELECTION_COUNTER is 1, the MAC entity may randomly select a value in the [0,1] interval with equal probability higher than the probability set by RRC in "sl-ProbResourceKeep" and the options below apply;

[0412] Option 1: If the transmission corresponds to the last transmission of a MAC PDU, the terminal may decrement the SL_RESOURCE_RESELECTION_COUNTER by 1 (if available) even if the last transmission has not been sent due to an SL LBT failure.

[0413] Option 2: When the terminal determines the last transmission of a MAC PDU for SL_RESOURCE_RESELECTION_COUNTER, if the transmission of a MAC PDU has not been caused by an LBT failure, the failed transmission may not be included in the number of transmissions of the MAC PDU.

[0414] “sl-ProbResourceKeep” may be scaled up or down based on consistent LBT failures for SL. A certain number of LBT failures for a selected sidelink grant or SL BWP may increase or decrease the value of “sl-ProbResourceKeep”. As an example, “sl-ProbResourceKeep” may be multiplied by N / 10, where N is determined by the number of LBT failures or consistent LBT failures triggered.

[0415] - when a resource pool is configured or reconfigured by RRC; or

[0416] - the selected resource pool does not have a selected sidelink grant; or

[0417] - if the resources of the selected sidelink grant are not within a Channel Occupancy Time (COT) period determined by a channel access procedure performed by the terminal or shared by any terminal / gNB / eNB; or

[0418] - A consistent LBT failure is triggered for the selected sidelink grant; or

[0419] - if a consistent LBT failure is triggered for an active SL BWP of the serving cell associated with the sidelink grant selected in the step; or

[0420] - consistent LBT failures are triggered for all SL BWPs of the serving cell associated with the selected sidelink grant; or

[0421] - on the serving cell associated with the selected sidelink grant if a consistent LBT failure has been triggered for SL or UL and has not been revoked; or

[0422] - if no transmission or retransmission has actually been performed by the MAC entity on the resources indicated in the selected sidelink grant during the last second and the following alternative applies; or

[0423] Alternative 1: If no MAC PDU transmission is caused by an LBT failure, then the failed transmission may not actually be considered as a (re)transmission.

[0424] Alternative 2: If an LBT failure prevents the transmission of a MAC PDU, the failed transmission may be considered as a real (re)transmission.

[0425] If "sl-ReselectAfter" is set and the number of consecutive unused transmission opportunities for the resources indicated in the selected sidelink grant is equal to "sl-ReselectAfter" and the following alternative applies; or

[0426] Alternative 1: If a MAC PDU transmission is not performed due to an LBT failure, the transmission opportunity of the failed transmission may not be considered as an unused transmission opportunity for "sl-ReselectAfter".

[0427] Alternative 2: If a MAC PDU transmission is not performed due to an LBT failure, the transmission opportunity of the failed transmission may be considered as an unused transmission opportunity for "sl-ReselectAfter".

[0428] - if the selected sidelink grant cannot accommodate the RLC SDU with the maximum allowed MCS configured by RRC in "sl-MaxMCS-PSSCH" and the terminal chooses not to segment the RLC SDU; or

[0429] - if the selected transmission for which a sidelink grant is available cannot meet the latency requirements of data on a logical channel with associated priority and the MAC entity chooses not to transmit the corresponding transmission for a single MAC PDU:

[0430] if the Tx terminal receives an SL NACK in response to a MAC PDU transmission at the last transmission opportunity within the COT period determined by a channel access procedure performed by the terminal or shared by any UE / gNB / eNB for a selected sidelink grant and one or more retransmissions of the MAC PDU are still required (e.g. due to a maximum number of transmissions of the MAC PDU); or

[0431] if, after the MAC PDU transmission at the last transmission opportunity within the COT period determined by a channel access procedure performed by the terminal or shared by any UE / gNB / eNB for the selected sidelink grant, one or more retransmissions of the MAC PDU are still required (e.g. due to a maximum number of MAC PDU transmissions with deactivated HARQ feedback),

[0432] - If the next transmission opportunity for the selected sidelink grant can meet the delay requirement or the remaining PDB of the MAC PDU (and the next transmission opportunity is within the next COT):

[0433] The terminal may retransmit the MAC PDU at the next COT using the next transmission opportunity of the selected sidelink grant.

[0434] - Otherwise (i.e. the next transmission opportunity for the selected sidelink grant cannot meet the delay requirement or the remaining PDB of the MAC PDU):

[0435] Alternative 1-1: The terminal may reserve additional resources within the COT and add the additional reserved resources to the selected sidelink grant (i.e., the terminal does not have to clear the selected sidelink grant).

[0436] Alternative 1-2: The terminal may revoke the selected sidelink grant associated with the sidelink process and trigger Tx resource (re)selection.

[0437] If the terminal is unable to reserve (additional) resources in the COT via alternative 1 or alternative 1-2 and the next transmission opportunity for the selected sidelink grant does not meet the delay requirement or the remaining PDB of the MAC PDU, the terminal may drop the MAC PDU, flush the buffer of the HARQ process in which the MAC PDU is stored, or consider that the terminal has reached the maximum number of transmissions of the MAC PDU.

[0438] Once the MAC entity has confirmed the Tx resource (re)selection for the selected resource pool for that sidelink process, the Tx terminal may, if possible, release the selected sidelink grant associated with that sidelink process and trigger a Tx resource (re)selection.

[0439] As an example of the present disclosure, the terminal may perform at least one of the alternatives described below.

[0440] If a consistent LBT failure is triggered for the selected sidelink grant; or

[0441] If a consistent LBT failure is triggered for the active SL BWP of the serving cell associated with the selected sidelink grant by the above-mentioned scheme; or

[0442] if a consistent LBT failure is triggered for all SL BWPs of the serving cell associated with the selected sidelink grant; or

[0443] If a consistent LBT failure has been triggered for SL or UL in the serving cell associated with the selected sidelink grant and has not been cancelled:

[0444] Alternative 6-1: The terminal may reselect a new resource pool from the old SL resource pool, which triggers a reselection to generate a newly selected sidelink grant for the terminal, where the currently selected sidelink grant may be reserved in the old SL resource pool.

[0445] Alternative 6-2: The UE may reselect a new RB set for the activated SL BWP from the previous RB set of the activated SL BWP, which triggers reselection to generate a newly selected sidelink grant for the UE, where the currently selected sidelink grant may be reserved in the previous RB set.

[0446] Alternative 6-3: The UE may reselect a new SL BWP from the previous SL BWP, which triggers a reselection to generate a newly selected sidelink grant for the UE, where the currently selected sidelink grant may be reserved for the previous SL BWP set.

[0447] Alternative 6-4: The UE may reselect from the previous cell to a new cell which triggers a reselection to generate a newly selected sidelink grant for the UE, where the currently selected sidelink grant may be reserved on the carrier of the previous cell.

[0448] In the above alternatives, 'lbt-FailureInstanceMaxCount' for consistent LBT failure detection may be set to other values ​​for other alternatives.

[0449] Additionally or alternatively, the 'lbt-FailureDetectionTimer' for consistent LBT failure detection may be set to other values ​​for other alternatives.

[0450] For example, the base station may set different "lbt-FailureInstanceMaxCount" values ​​for different alternatives. For example, the "lbt-FailureInstanceMaxCount" value for alternative 6-1 may be lower than the "lbt-FailureInstanceMaxCount" value for alternative 6-3.

[0451] Or, the base station may set different "lbt-FailureDetectionTimer" values ​​for different alternatives, such that the "lbt-FailureDetectionTimer" value for alternative 6-4 may be lower than the "lbt-FailureDetectionTimer" value for alternative 6-3.

[0452] The 'lbt-FailureInstanceMaxCount' for consistent LBT failure detection and the 'lbt-FailureDetectionTimer' for consistent LBT failure detection may be set to different values ​​for SL mode 1 (i.e., SL resource allocation mode 1) and SL mode 2 (i.e., SL resource allocation mode 2).

[0453] For SL mode 1, the above mentioned parameters may be used for SR reporting. For SL mode 2, the above mentioned parameters may be used for resource reselection. Additionally or alternatively, for both SL mode 1 and SL mode 2, SR may be triggered by consistent LBT errors in the above mentioned steps.

[0454] Additionally or alternatively, if a consistent LBT failure is triggered for the selected sidelink grant; or

[0455] If, during the above steps, a consistent LBT failure is triggered for the active SL BWP of the serving cell associated with the selected sidelink grant; or

[0456] if a consistent LBT failure is triggered for all SL BWPs of the serving cell associated with the selected sidelink grant; or

[0457] If a consistent LBT failure has been triggered for SL or UL and has not been cancelled, then in the serving cell associated with the selected sidelink grant:

[0458] - If the Tx UE establishes a PC5-RRC connection with the RX UE,

[0459] Option 6-1: The MAC entity of the Tx terminal assumes that sidelink RLF is detected and can inform the RRC of the Tx terminal of "sidelink RLF detection."

[0460] Option 6-2: The MAC entity of the Tx terminal may assume that a consistent SL LBT failure has been detected and may inform the RRC of the Tx terminal of "consistent SL LBT failure".

[0461] The Tx UE can send a PC5-RRC release message to the Rx UE to release the PC5-RRC connection with the Rx UE. Upon receiving the PC5-RRC release message, the Rx UE can release the PC5-RRC connection with the Tx UE.

[0462] The terminal may perform re-evaluation or pre-emption in the manner described below.

[0463] The resources of the sidelink grant selected for a MAC PDU to be transmitted from the multiplexing and assembly entity may be re-evaluated by the physical layer T3 prior to the slot in which the SCI indicating the resources is first signaled. The resources of the selected sidelink grant indicated by a previous SCI for transmitting a MAC PDU from the multiplexing and assembly entity may be checked for preemption by the physical layer T3 prior to the slot in which the resources are located.

[0464] Before 'm-T3' or after 'm-T3', but reevaluation or preemption before 'm' may vary depending on the terminal implementation. For reevaluation, m refers to the slot in which the SCI indicating the resource is first signaled. In the case of preemption, m can refer to the slot in which the resource is located.

[0465] If the sidelink resource allocation mode 2 is configured for the terminal MAC entity to transmit using a resource pool of carriers or based on sensing or random selection, the terminal MAC entity may, for each sidelink process, proceed as follows:

[0466] 1> when resources of a selected sidelink grant not previously identified by the SCI are indicated for re-evaluation by the physical layer;

[0467] 2>Removing resources from the selected sidelink grant associated with the sidelink process;

[0468] 2> If a PSFCH is configured for this resource pool and resources can be indicated by the time resource allocation of the SCI for retransmission, select an arbitrary time and frequency resource from among the resources indicated by the physical layer for the removed or dropped resource by ensuring a minimum time interval between two selected resources of the selected sidelink grant, depending on the amount of selected frequency resources, the number of selected HARQ retransmissions and the remaining PDB of SL data available for the logical channel;

[0469] 2> Replace the removed or deleted resources with the selected resources for the selected sidelink grant.

[0470] 1> The selected sidelink grant resource is not within a COT (Channel Occupancy Time) period determined by a channel access procedure performed by the terminal or shared by any terminal / gNB / eNB; or

[0471] 1>When the resources of the selected sidelink grant are not available for SL transmission due to an LBT failure indication in L1;

[0472] 2>Removing resources from the selected sidelink grant associated with the sidelink process;

[0473] 2> If a PSFCH is configured for this resource pool and resources can be indicated by the time resource allocation of the SCI for retransmissions, select an arbitrary time and frequency resource from the resources indicated by the physical layer for the removed or dropped resource by guaranteeing a minimum time interval between any two selected resources of the selected sidelink grant, depending on the amount of arbitrarily selected frequency resources, the number of selected HARQ retransmissions and the remaining PDB of SL data available for the logical channel;

[0474] 2> Replace the removed or deleted resources with the selected resources for the selected sidelink grant.

[0475] 1> If resources of the selected sidelink grant, previously indicated by the SCI, are indicated for pre-emption by the physical layer;

[0476] 2> If one or more SL DRXs are configured:

[0477] 3>Removing resources from the selected sidelink grant associated with the sidelink process;

[0478] 3> if a PSFCH is configured for this resource pool and resources can be indicated by the time resource allocation of the SCI for retransmission, select an arbitrary time and frequency resource from among the resources after the resources for the removed or dropped resources indicated by the previous SCI by ensuring a minimum time interval between the two selected resources of the selected sidelink grant, according to the amount of selected frequency resources, the number of selected HARQ retransmissions and the remaining PDB of SL data available for the logical channel;

[0479] 3> Replace the removed or deleted resources with the selected resources for the selected sidelink grant.

[0480] 2>If not:

[0481] 3>Removing resources from the selected sidelink grant associated with the sidelink process;

[0482] 3>Selection of time and frequency resources from among the resources indicated by the physical layer for the removed or dropped resources according to the amount of arbitrarily selected frequency resources, the number of selected HARQ retransmissions and the remaining PDB of SL data available for the logical channel, by ensuring a minimum time interval between two selected resources of the selected sidelink grant, if a PSFCH is configured for this resource pool and resources can be indicated by the time resource allocation of the SCI for retransmission;

[0483] 3> Replace the removed or deleted resources with the selected resources for the selected sidelink grant.

[0484] Here, the method of determining whether resources can be indicated by the time resource allocation of the previous SCI and selecting time and frequency resources for one or more transmission opportunities from available resources if a retransmission resource cannot be selected may be based on the terminal implementation by ensuring a minimum time interval between two selected resources when a PSFCH is configured for the resource pool.

[0485] The terminal implementation may be left to reselect preselected but unreserved resources in addition to the resources indicated for preemption or reevaluation by the physical layer during reselection triggered by a physical layer indicated reevaluation or preemption.

[0486] Whether or not to set a resource reservation interval in the reselected resource to replace the preempted resource may vary depending on the terminal implementation. Whether or not to trigger resource reselection by deprioritization may vary depending on the terminal implementation.

[0487] If the selected sidelink grant corresponds to the transmission of multiple MAC PDUs, it may depend on the UE implementation whether or not to immediately apply the re-evaluation confirmation to resources of the non-initial reservation period that have not been signaled in the last or current period.

[0488] In the Tx terminal, for each SCI and SL grant corresponding to a new transmission, the MAC entity may perform a logical channel priority procedure to select a destination associated with a MAC CE and one of unicast, groupcast and broadcast having at least one of the highest priority logical channels from among the logical channels and MAC CEs (for the SL grant associated with the SCI) that satisfy all of the following conditions:

[0489] Here, the conditions may include: i) transmission of SL data is possible; ii) there is a logical channel for which SBj (sidelink bucket size / value for logical channel j)>0, SBj>0; iii) 'sl-configuredGrantType1Allowed' is set to 'true' if the SL grant is of configured grant type 1 (if configured); iv) 'sl-AllowedCG-List' contains the configured grant index associated with the SL grant (if configured); and v) 'sl-HARQ-FeedbackEnabled' is set as deactivated if the PSFCH is not configured for the SL grant associated with the SCI.

[0490] If multiple destinations have logical channels with the same highest priority that satisfy all the above conditions, or if multiple destinations have MAC CE and / or logical channels with the same priority as the MAC CE that satisfy all the above conditions, the selection of a specific destination from among the above destinations may be based on the terminal implementation.

[0491] If at this stage the PSFCH is configured for a sidelink grant associated with the SCI and any successive SL grants used for the transmission of MAC PDUs generated for this procedure can satisfy the minimum time interval:

[0492] - the MAC entity sets "sl-HARQ-FeedbackEnabled" as active if "sl-HARQ-FeedbackEnabled" is set as active for the logical channel with the highest priority that satisfies said condition; or

[0493] - The MAC entity may set "sl-HARQ-FeedbackEnabled" as deactivated if "sl-HARQ-FeedbackEnabled" is set as deactivated for the logical channel with the highest priority that satisfies said condition.

[0494] On the other hand, if a PSFCH is not configured for a sidelink grant associated with the SCI or if successive SL grants used for the transmission of the MAC PDUs generated for the procedure do not meet the minimum time interval, the MAC entity may set “sl-HARQ-FeedbackEnabled” as deactivated.

[0495] If the MAC entity sets "sl-HARQ-FeedbackEnabled" as active, the MAC entity can select logical channels with "sl-HARQ-FeedbackEnabled" set as active. If the MAC entity sets "sl-HARQ-FeedbackEnabled" as inactive, the MAC entity can select logical channels with "sl-HARQ-FeedbackEnabled" set as inactive.

[0496] Then, for each SCI and SL grant corresponding to a new transmission, the MAC entity can generate a MAC PDU containing SL data only on the logical channels selected for the HARQ entity, where logical channels with "sl-HARQ-FeedbackEnabled" set as enabled and logical channels with "sl-HARQ-FeedbackEnabled" set as disabled cannot be multiplexed into the same MAC PDU.

[0497] In the transmitting terminal, for each sidelink grant of the selected sidelink grant, if the MAC entity determines that the sidelink grant is used for the initial transmission or if the sidelink grant is a configured sidelink grant and no MAC PDU has been obtained in the “sl-PeriodCG” of the configured sidelink grant, the MAC entity may obtain the MAC PDU generated in the above-mentioned steps.

[0498] Upon obtaining a MAC PDU to transmit, the MAC entity can determine the TB sidelink transmission information for the source and destination pair of the MAC PDU as described below.

[0499] Upon obtaining a MAC PDU to transmit, the MAC entity can determine the TB sidelink transmission information for the source and destination pair of the MAC PDU as follows:

[0500] - A MAC entity can set the Source Layer 1 ID to the 8 LSBs of the Source Layer 2 ID of a MAC PDU.

[0501] - A MAC entity can set the destination Layer 1 ID to 16 LSBs of the destination Layer 2 ID of a MAC PDU.

[0502] - The MAC entity may determine that the NDI has been toggled by comparing the Sidelink Identification Information and the previously transmitted value corresponding to the Sidelink Process ID of the MAC PDU and set the NDI to the toggled value.

[0503] - The MAC entity can set the cast type indicator to one of broadcast, groupcast, and unicast as instructed by higher layers.

[0504] - If HARQ feedback is activated for a MAC PDU by the logical channel priority procedure, the MAC entity may set the HARQ feedback activation / deactivation indicator to active.

[0505] - If HARQ feedback is deactivated for a MAC PDU by the logical channel priority procedure, the MAC entity may set the HARQ feedback activation / deactivation indicator to deactivated.

[0506] - The MAC entity may set as priority the highest priority value of the logical channel (if any) and, if included in the MAC PDU, the MAC CE (if included).

[0507] - If both the group size and the member ID are provided by higher layers and the group size is not larger than the number of candidate PSFCH resources associated with the sidelink grant, the MAC entity may select a positive-negative ACK or a negative-only grant, otherwise the MAC entity may select a negative-only grant.

[0508] - When selecting the negative-only ACK, if the terminal location information is available and "sl-TransRange" is set for the logical channel in the MAC PDU and "sl-ZoneConfig" is set, the MAC entity may set the communication range requirement to the longest communication range value of the logical channel in the MAC PDU.

[0509] The MAC entity may determine the “sl-ZoneLength” value corresponding to the coverage requirement, set the “Zone_id” value calculated using the determined “sl-ZoneLength” value as “Zone_id”, and perform a new transmission of the MAC PDU on the PSSCH using a sidelink grant.

[0510] A Tx terminal can monitor the PSFCH opportunities and determine a positive ACK or negative ACK for a MAC PDU based on the PSFCH transmission made by the Rx terminal.

[0511] If the Tx terminal decides on a negative acknowledgement and the sidelink grant for the selected sidelink grant is retransmittable, the MAC entity can perform a retransmission of the MAC PDU on the PSSCH using the sidelink grant.

[0512] In the description of this disclosure, sidelink transmission, grant and resources may be replaced with uplink transmission, grant and resources. The terminal may change the resource pool or SL BWP or RB set or serving cell from which the SL transmission is made (when the terminal autonomously decides on a new transmission or retransmission up to a maximum of N transmissions of a TB in a resource pool) based on consistent SL LBT failures.

[0513] Apparatuses to which the present disclosure can be applied

[0514] FIG. 13 illustrates a block diagram of a wireless communication device according to an embodiment of the present disclosure.

[0515] Referring to FIG. 13, a first device 100 and a second device 200 can transmit and receive wireless signals via various wireless access technologies (e.g., LTE, NR).

[0516] The first device 100 includes one or more processors 102 and one or more memories 104, and may further include one or more transceivers 106 and / or one or more antennas 108. The processor 102 may be configured to control the memory 104 and / or the transceiver 106 to implement the descriptions, functions, procedures, suggestions, methods and / or operational flow diagrams disclosed in the present disclosure.

[0517] For example, the processor 102 may process the information in the memory 104 to generate a first information / signal and then transmit a wireless signal including the first information / signal from the transceiver 106. The processor 102 may also receive a wireless signal including a second information / signal from the transceiver 106 and then store in the memory 104 information resulting from signal processing of the second information / signal.

[0518] The memory 104 may be coupled to the processor 102 and may store various information related to the operation of the processor 102. For example, the memory 104 may store software code including instructions for performing a part or all of the processes controlled by the processor 102 or for executing the descriptions, functions, procedures, suggestions, methods and / or operational flow diagrams disclosed in the present disclosure. Here, the processor 102 and the memory 104 may be part of a communication modem / circuit / chip designed to embody a wireless communication technology (e.g., LTE, NR). The transceiver 106 may be coupled to the processor 102 and may transmit and / or receive wireless signals via one or more antennas 108. The transceiver 106 may include a transmitter and / or a receiver. The transceiver 106 may be referred to as a Radio Frequency (RF) unit. In the present disclosure, the device may mean a communication modem / circuit / chip.

[0519] The second device 200 may include one or more processors 202, one or more memories 204, and may further include one or more transceivers 206 and / or one or more antennas 208. The processor 202 may be configured to control the memory 204 and / or the transceiver 206 to implement the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams disclosed in the present disclosure. For example, the processor 202 may process information in the memory 204 to generate a third information / signal, and then transmit a wireless signal including the third information / signal from the transceiver 206. The processor 202 may also receive a wireless signal including a fourth information / signal from the transceiver 206, and then store information obtained from signal processing of the fourth information / signal in the memory 204. The memory 204 may be coupled to the processor 202 and may store various information related to the operation of the processor 202. For example, the memory 204 may store software code including instructions for performing some or all of the processes controlled by the processor 202 or executing the descriptions, functions, procedures, suggestions, methods and / or operational flow diagrams disclosed in the present disclosure. Here, the processor 202 and the memory 204 may be part of a communication modem / circuit / chip designed to embody a wireless communication technology (e.g., LTE, NR). The transceiver 206 may be coupled to the processor 202 and may transmit and / or receive wireless signals via one or more antennas 208. The transceiver 206 may include a transmitter and / or a receiver. The transceiver 206 may be referred to as an RF unit. In the present disclosure, the device may refer to a communication modem / circuit / chip.

[0520] The hardware elements of the devices 100, 200 are described in more detail below. One or more protocol layers may be embodied by one or more processors 102, 202, without being limited thereto. For example, one or more processors 102, 202 may embody one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, SDAP). One or more processors 102, 202 may generate one or more Protocol Data Units (PDUs) and / or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams disclosed in the present disclosure. One or more processors 102, 202 may generate messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams disclosed in the present disclosure. The one or more processors 102, 202 can generate and provide signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information to one or more transceivers 106, 206 according to the functions, procedures, suggestions, and / or methods disclosed in this disclosure. The one or more processors 102, 202 can receive signals (e.g., baseband signals) from the one or more transceivers 106, 206 and obtain the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams disclosed in this disclosure.

[0521] The one or more processors 102, 202 may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. The one or more processors 102, 202 may be embodied in hardware, firmware, software, or a combination thereof. As an example, one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), or one or more field programmable gate arrays (FPGAs) may be included in the one or more processors 102, 202. The descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams disclosed in the present disclosure may be embodied using firmware or software, and the firmware or software may be embodied to include modules, procedures, functions, etc. Firmware or software configured to execute the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure may be included in one or more processors 102, 202 or stored in one or more memories 104, 204 and executed by one or more processors 102, 202. The descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure may be embodied in firmware or software in the form of code, instructions and / or collections of instructions.

[0522] One or more memories 104, 204 may be coupled to one or more processors 102, 202 and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories 104, 204 may be comprised of ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer readable storage media, and / or combinations thereof. The one or more memories 104, 204 may be located internal and / or external to the one or more processors 102, 202. Also, the one or more memories 104, 204 may be coupled to the one or more processors 102, 202 by various techniques, such as wired or wireless coupling.

[0523] The one or more transceivers 106, 206 may transmit user data, control information, wireless signals / channels, etc., as referred to in the methods and / or operational flow diagrams of the present disclosure, to one or more other devices. The one or more transceivers 106, 206 may receive user data, control information, wireless signals / channels, etc., as referred to in the descriptions, functions, procedures, suggestions, methods and / or operational flow diagrams of the present disclosure, from one or more other devices. For example, the one or more transceivers 106, 206 may be coupled to one or more processors 102, 202 and may transmit and receive wireless signals. For example, the one or more processors 102, 202 may control the one or more transceivers 106, 206 to transmit user data, control information, or wireless signals to one or more other devices. Also, the one or more processors 102, 202 may control the one or more transceivers 106, 206 to receive user data, control information, or wireless signals from one or more other devices. In addition, one or more transceivers 106, 206 may be coupled to one or more antennas 108, 208, and the one or more transceivers 106, 206 may be configured to transmit and receive user data, control information, radio signals / channels, etc., as described, functions, procedures, suggestions, methods, and / or operation flow diagrams disclosed in the present disclosure, via the one or more antennas 108, 208. In the present disclosure, the one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). The one or more transceivers 106, 206 may convert the received radio signals / channels, etc., from RF band signals to baseband signals for processing the received user data, control information, radio signals / channels, etc., using one or more processors 102, 202. The one or more transceivers 106, 206 may convert the user data, control information, radio signals / channels, etc., processed using one or more processors 102, 202, from baseband signals to RF band signals. To that end, one or more of the transceivers 106, 206 may include (analog) oscillators and / or filters.

[0524] The above-described embodiments are combinations of the components and features of the present disclosure in a predetermined form. Each component or feature should be considered as optional unless otherwise expressly stated. Each component or feature may be implemented in a form not combined with other components or features. It is also possible to combine some components and / or features to configure the embodiments of the present disclosure. The order of operations described in the embodiments of the present disclosure may be changed. Some configurations or features of one embodiment may be included in another embodiment, or may be replaced with corresponding configurations or features of another embodiment. It is clear that claims that do not have an explicit reference relationship in the claims may be combined to configure an embodiment, or may be included as a new claim by amendment after filing.

[0525] It is obvious to those skilled in the art that the present disclosure can be embodied in other specific forms without departing from the essential features of the present disclosure. Therefore, the above detailed description should not be interpreted as limiting in any respect, but should be considered as illustrative. The scope of the present disclosure should be determined by a reasonable interpretation of the attached claims, and any modifications within the equivalent scope of the present disclosure are included in the scope of the present disclosure.

[0526] The scope of the present disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) that cause a device or computer to perform operations according to the methods of various embodiments, and non-transitory computer-readable media on which such software or instructions or the like can be stored and executed on a device or computer. Instructions available for programming a processing system to perform features described in the present disclosure may be stored on / in a storage medium or computer-readable storage medium, and computer program products including such storage media may be used to embody features described in the present disclosure. The storage medium may include high-speed random access memory, such as DRAM, SRAM, DDR RAM, or other random access solid-state memory devices, but is not limited thereto, and may include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid-state storage devices. The memory optionally includes one or more storage devices that are located remotely from the processor. The memory or alternatively the non-volatile memory devices in the memory include non-transitory computer-readable storage media. The features described in this disclosure may be embodied in software and / or firmware stored on any one of a number of machine-readable media and capable of controlling the hardware of a processing system and allowing the processing system to interact with other mechanisms that utilize the results of embodiments of the present disclosure. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0527] Here, the wireless communication technology implemented in the devices 100 and 200 of the present disclosure may include LTE, NR, and 6G as well as Narrowband Internet of Things (NB-IoT) for low power communication. At this time, for example, the NB-IoT technology may be an example of a Low Power Wide Area Network (LPWAN) technology, and may be implemented according to standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the above names. Additionally or alternatively, the wireless communication technology implemented in the devices 100 and 200 of the present disclosure may perform communication based on the LTE-M technology. At this time, as an example, the LTE-M technology may be an example of an LPWAN technology, and may be called various names such as eMTC (enhanced Machine Type Communication). For example, the LTE-M technology may be embodied by at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and is not limited to the above names. Additionally or alternatively, the wireless communication technology embodied in the devices 100 and 200 of the present disclosure may include at least one of ZigBee (registered trademark), Bluetooth (registered trademark), and Low Power Wide Area Network (LPWAN), which consider low power communication, and is not limited to the above names. As an example, the ZigBee technology may generate personal area networks (PANs) related to small / low power digital communication based on various standards such as IEEE 802.15.4, and may be called various names. [Industrial Applicability]

[0528] The method proposed in this disclosure has been described mainly as being applied to 3GPP LTE / LTE-A and 5G systems, but it can also be applied to various wireless communication systems other than 3GPP LTE / LTE-A and 5G systems.

Claims

1. 1. A method performed by a first terminal in a wireless communication system, the method comprising: receiving configuration information associated with a plurality of sidelink (SL) resource pools and a plurality of resource block (RB) sets from a base station; Detecting and triggering a consistent SL listen before talk (LBT) failure for at least one of a first SL resource pool or a first RB set among the plurality of SL resource pools and the plurality of RB sets; The method includes a step of triggering SL resource reselection to select a second SL resource pool or a second RB set from among the plurality of resource pools and the plurality of RB sets based on the triggered consistent SL LBT failure not being cancelled.

2. The method of claim 1 , wherein a selected SL grant corresponding to at least one of the first SL resource pool or the first RB set is removed.

3. The second SL resource pool is selected from among the plurality of resource pools based on the consistent SL LBT being triggered a first number of times; The method of claim 1 , further comprising selecting the second RB set from among the plurality of RB sets based on the consistent SL LBT being triggered a second number of times.

4. a second selected sidelink grant is generated based on at least one of the second SL resource pool or the second RB set; 2. The method of claim 1, wherein a medium access control (MAC) protocol data unit (PDU) based on the second selected sidelink grant is transmitted to a second terminal.

5. The method of claim 1, wherein the triggered consistent SL LBT is cancelled based on configuration information related to an LBT failure recovery procedure being reconfigured by the base station.

6. The method of claim 5, wherein an SL LBT counter value for determining whether to trigger the consistent SL LBT is set to 0 based on the triggered consistent SL LBT being canceled or a timer associated with the detection of the consistent SL LBT expiring.

7. The method of claim 1 , wherein configuration information related to SL resource allocation mode 2 is received from the base station by RRC signaling.

8. 2. The method of claim 1, wherein the SL resource reselection is triggered based on a lack of a physical sidelink shared channel (PSSCH) transmission due to the triggered consistent SL LBT failure.

9. 2. The method of claim 1, wherein the SL resource reselection is triggered in a second SL BWP or a second cell to generate a third selected SL grant based on the consistent SL LBT triggered in a first SL BWP or a first cell not being revoked.

10. A first terminal in a wireless communication system, the first terminal comprising: one or more transceivers; one or more processors coupled to the one or more transceivers; The one or more processors: receiving configuration information associated with a plurality of sidelink (SL) resource pools and a plurality of resource block (RB) sets from a base station via the one or more transceivers; Detect and trigger a consistent SL listen before talk (LBT) failure for at least one of a first SL resource pool or a first RB set among the plurality of SL resource pools and the plurality of RB sets; A first terminal configured to trigger SL resource reselection to select a second SL resource pool or a second RB set from among the plurality of resource pools and the plurality of RB sets based on the triggered consistent SL LBT failure not being cancelled.

11. 1. A method performed by a base station in a wireless communication system, the method comprising: transmitting configuration information related to a plurality of sidelink (SL) resource pools and a plurality of resource block (RB) sets to a first terminal; receiving from the first terminal a MAC CE associated with a consistent SL listen before talk (LBT) failure for at least one of a first SL resource pool or a first RB set among the plurality of SL resource pools and the plurality of RB sets; A method in which SL resource reselection is triggered by the first terminal to select a second SL resource pool or a second RB set from among the multiple resource pools and the multiple RB sets based on the triggered consistent SL LBT failure not being canceled.

12. A base station in a wireless communication system, the base station comprising: one or more transceivers; one or more processors coupled to the one or more transceivers; The one or more processors: Transmitting configuration information related to a plurality of sidelink (SL) resource pools and a plurality of resource block (RB) sets to a first terminal via the one or more transceivers; and receiving, from the first terminal via the one or more transceivers, a MAC CE associated with a consistent SL listen before talk (LBT) failure for at least one of a first SL resource pool or a first RB set among the plurality of SL resource pools and the plurality of RB sets; A base station, wherein SL resource reselection is triggered by the first terminal to select a second SL resource pool or a second RB set from among the plurality of resource pools and the plurality of RB sets based on the triggered consistent SL LBT failure not being canceled.

13. 1. A processing device configured to control a first terminal in a wireless communication system, the processing device comprising: one or more processors; one or more computer memories operatively coupled to the one or more processors and configured to store instructions that perform operations based on being executed by the one or more processors; The operation includes: receiving configuration information associated with a plurality of sidelink (SL) resource pools and a plurality of resource block (RB) sets from a base station; Detecting and triggering a consistent SL listen before talk (LBT) failure for at least one of a first SL resource pool or a first RB set among the plurality of SL resource pools and the plurality of RB sets; and an operation of triggering SL resource reselection to select a second SL resource pool or a second RB set from among the plurality of resource pools and the plurality of RB sets based on the triggered consistent SL LBT failure not being cancelled.

14. one or more non-transitory computer-readable media storing one or more instructions, The one or more instructions are executed by one or more processors, such that an apparatus in a wireless communication system comprises: Receive configuration information related to a plurality of sidelink (SL) resource pools and a plurality of resource block (RB) sets from a base station; Detect and trigger a consistent SL listen before talk (LBT) failure for at least one of a first SL resource pool or a first RB set among the plurality of SL resource pools and the plurality of RB sets; A computer-readable medium controlled to trigger SL resource reselection to select a second SL resource pool or a second RB set from among the plurality of resource pools and the plurality of RB sets based on the triggered consistent SL LBT failure not being cancelled.

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