Method and apparatus for performing Mode 1 SL communication in NR V2X

Abstract

A method for a first device to perform wireless communication and an apparatus supporting the method are provided. The method includes the following steps: receiving information related to a first side link (SL) grant, information related to a first physical uplink control channel (PUCCH) resource, and information related to a maximum number of transmissions of a medium access control protocol data unit (MAC PDU) from a base station; sending a MAC PDU to a second device based on a first SL grant and a SL hybrid automatic repeat request (HARQ) process ID; refreshing a buffer associated with the SL HARQ process ID based on the number of times the MAC PDU is sent to the second device reaching the maximum number of transmissions; and receiving downlink control information (DCI) related to the SL HARQ process ID from the base station through a physical downlink control channel (PDCCH), the DCI including information related to a second SL grant for retransmission of the MAC PDU and information related to a second PUCCH resource, wherein, based on the buffer associated with the SL HARQ process ID being refreshed, the first device does not send a MAC PDU to the second device based on the second SL grant, and the first device may not send SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system. Background Art

[0002] Sidelink (SL) communication is a communication scheme in which a direct link is established between user equipments (UEs) and the UEs exchange voice and data directly with each other without the intervention of an evolved Node B (eNB). SL communication is being considered as a solution to the eNB overhead caused by the rapid growth of data services. V2X (Vehicle to Everything) refers to a communication technology used by vehicles to exchange information with other vehicles, pedestrians, and objects equipped with infrastructure. V2X can be divided into four types such as V2V (Vehicle to Vehicle), V2I (Vehicle to Infrastructure), V2N (Vehicle to Network), and V2P (Vehicle to Pedestrian). V2X communication can be provided through a PC5 interface and / or a Uu interface.

[0003] In addition, as more and more communication devices require larger communication capacity, the need for enhanced mobile broadband communication relative to traditional radio access technology (RAT) is rising. Therefore, the design of communication systems taking into account UEs or services that are sensitive to reliability and latency has also been discussed. In addition, the next generation of radio access technologies based on enhanced mobile broadband communication, massive machine type communication (MTC), ultra-reliable low latency communication (URLLC), etc. can be referred to as new RAT (radio access technology) or NR (new radio). In this article, NR can also support vehicle-to-everything (V2X) communication.

[0004] Figure 1 is a diagram for describing NR-based V2X communication compared with V2X communication based on a RAT used before NR. Figure 1 The embodiments of the present disclosure may be combined with various embodiments of the present disclosure.

[0005] Regarding V2X communication, when discussing the RAT used before NR, the focus is on the scheme of providing safety services based on V2X messages such as BSM (Basic Safety Message), CAM (Cooperative Awareness Message) and DENM (Decentralized Environment Notification Message). V2X messages may include location information, dynamic information, attribute information, etc. For example, a UE may send a periodic message type CAM and / or an event-triggered message type DENM to another UE.

[0006] Since then, various V2X scenarios have been proposed in NR regarding V2X communication. For example, these various V2X scenarios may include vehicle platooning, advanced driving, extended sensors, remote driving, etc. Summary of the invention

[0007] Technical Purpose

[0008] In addition, the sending UE can perform SL communication based on the resources allocated by the base station (for example, SL configuration grant (CG)). In this case, it is necessary to clearly define a method for the sending UE to operate a buffer of the associated SL HARQ process if the number of transmissions performed by the sending UE based on a specific SL CG reaches a preconfigured maximum number of transmissions related to the specific SL CG, a method for the sending UE to operate retransmission resources related to a dynamic grant (DG) received from the base station after the sending UE reports NACK information (received from the receiving UE) to the base station based on the PUCCH resources related to the SL CG, a method for the sending UE to operate PUCCH resources related to the retransmission resources, etc.

[0009] Technical Solution

[0010] In one embodiment, a method for performing wireless communication by a first device is provided. The method may include the following steps: receiving information related to a first side link (SL) grant, information related to a first physical uplink control channel (PUCCH) resource, and information related to a maximum number of transmissions of a medium access control (MAC) protocol data unit (PDU) from a base station; sending a MAC PDU to a second device based on a first SL grant and a SL hybrid automatic repeat request (HARQ) process ID; refreshing a buffer related to the SL HARQ process ID based on the number of transmissions of the MAC PDU to the second device reaching the maximum number of transmissions; and receiving downlink control information (DCI) related to the SL HARQ process ID from the base station through a physical downlink control channel (PDCCH), wherein the DCI includes information related to a second SL grant for retransmission of the MAC PDU and information related to a second PUCCH resource. For example, based on the buffer related to the SL HARQ process ID being refreshed, the first device may not send the MAC PDU to the second device based on the second SL grant, and the first device may not send SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

[0011] In one embodiment, a first device configured to perform wireless communication is provided. The first device may include: one or more memories storing instructions; one or more transceivers; and one or more processors connected to the one or more memories and the one or more transceivers. One or more processors may execute instructions to: receive information related to a first side link (SL) grant, information related to a first physical uplink control channel (PUCCH) resource, and information related to the maximum number of transmissions of a medium access control (MAC) protocol data unit (PDU) from a base station; send a MAC PDU to a second device based on a first SL grant and a SL hybrid automatic repeat request (HARQ) process ID; based on the number of transmissions of the MAC PDU to the second device reaching the maximum number of transmissions, refresh the buffer related to the SL HARQ process ID; and receive downlink control information (DCI) related to the SL HARQ process ID from the base station through a physical downlink control channel (PDCCH), wherein the DCI includes information related to a second SL grant for retransmission of the MAC PDU and information related to a second PUCCH resource. For example, based on the buffer related to the SL HARQ process ID being flushed, the first device may not send the MAC PDU to the second device based on the second SL grant, and the first device may not send the SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

[0012] Effects of the present disclosure

[0013] If the maximum number of transmissions for each SL CG is configured for the UE, the ambiguity in the UE's operations for performing SL communication can be eliminated. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a diagram for describing NR-based V2X communication compared with V2X communication based on a RAT used before NR.

[0015] Figure 2 The structure of the NR system based on the embodiment of the present disclosure is shown.

[0016] Figure 3 A radio protocol architecture according to an embodiment of the present disclosure is shown.

[0017] Figure 4 The structure of a radio frame of NR based on an embodiment of the present disclosure is shown.

[0018] Figure 5 The structure of the time slot of the NR frame based on the embodiment of the present disclosure is shown.

[0019] Figure 6An example of a BWP based on an embodiment of the present disclosure is shown.

[0020] Figure 7 A UE performing V2X or SL communication according to an embodiment of the present disclosure is shown.

[0021] Figure 8 A process of performing V2X or SL communication based on a transmission mode by a UE according to an embodiment of the present disclosure is shown.

[0022] Fig. 9 Three types of broadcasts based on embodiments of the present disclosure are shown.

[0023] Fig.10 The resource unit used for CBR measurement according to the embodiment of the present disclosure is shown.

[0024] Fig.11 A method according to an embodiment of the present disclosure is shown, in which a UE that has reserved transmission resources informs another UE of the transmission resources.

[0025] Fig.12 A case is shown in which a base station according to an embodiment of the present disclosure sends DCI related to transmission (retransmission) to a UE because the base station mistakenly recognizes ACK information sent by a TX UE as NACK information.

[0026] Fig.13 A case is shown in which a base station according to an embodiment of the present disclosure does not send DCI related to transmission (retransmission) to a UE because the base station mistakenly recognizes NACK information sent by a TX UE as ACK information.

[0027] Fig.14 The operation of a UE when a UE that has refreshed a buffer related to a HARQ process receives information on a retransmission resource related to the HARQ process according to an embodiment of the present disclosure is shown.

[0028] Fig.15 A method for a first device to perform wireless communication based on an embodiment of the present disclosure is shown.

[0029] Fig.16 A method for a base station to perform wireless communication based on an embodiment of the present disclosure is shown.

[0030] Fig.17 A communication system 1 according to an embodiment of the present disclosure is shown.

[0031] Fig.18 A wireless device according to an embodiment of the present disclosure is shown.

[0032] Fig.19A signal processing circuit for transmitting a signal according to an embodiment of the present disclosure is shown.

[0033] Fig. 20 Another example of a wireless device according to an embodiment of the present disclosure is shown.

[0034] Fig.21 A handheld device according to an embodiment of the present disclosure is shown.

[0035] Fig. 22 A vehicle or autonomous vehicle according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0036] In the present disclosure, "A or B" may mean "only A", "only B", or "both A and B". In other words, in the present disclosure, "A or B" may be interpreted as "A and / or B". For example, in the present disclosure, "A, B or C" may mean "only A", "only B", "only C", or "any combination of A, B, C".

[0037] A slash ( / ) or a comma used in the present disclosure may mean "and / or". For example, "A / B" may mean "A and / or B". Thus, "A / B" may mean "only A", "only B", or "both A and B". For example, "A, B, C" may mean "A, B, or C".

[0038] In the present disclosure, "at least one of A and B" may mean "only A", "only B", or "both A and B". In addition, in the present disclosure, the expression "at least one of A or B" or "at least one of A and / or B" may be interpreted as "at least one of A and B".

[0039] In addition, in the present disclosure, "at least one of A, B, and C" may mean "only A", "only B", "only C", or "any combination of A, B, and C". In addition, "at least one of A, B, or C" or "at least one of A, B and / or C" may mean "at least one of A, B, and C".

[0040] In addition, brackets used in the present disclosure may mean "for example". Specifically, when indicated as "control information (PDCCH)", this may mean proposing "PDCCH" as an example of "control information". In other words, the "control information" of the present disclosure is not limited to "PDCCH", and "PDCCH" may be proposed as an example of "control information". Specifically, when indicated as "control information (i.e., PDCCH)", this may also mean proposing "PDCCH" as an example of "control information".

[0041] The technical features respectively described in a pair of drawings in the present disclosure may be implemented separately or simultaneously.

[0042] The techniques described below can be used in various wireless communication systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), etc. CDMA can be implemented using radio technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA-2000. TDMA can be implemented using radio technologies such as Global System for Mobile Communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA can be implemented using radio technologies such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Evolved UTRA (E-UTRA), etc. IEEE802.16m is an evolved version of IEEE 802.16e and provides backward compatibility for systems based on IEEE 802.16e. UTRA is part of Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE uses OFDMA in the downlink and SC-FDMA in the uplink. LTE-Advanced (LTE-A) is an evolution of LTE.

[0043] 5G NR is a subsequent technology of LTE-A corresponding to a new mobile communication system with high performance, low latency, high availability, etc. 5G NR can use all available spectrum resources including low frequency bands less than 1 GHz, intermediate frequency bands from 1 GHz to 10 GHz, and high frequency (millimeter wave) above 24 GHz.

[0044] For the sake of clarity, the following description will mainly focus on LTE-A or 5G NR. However, the technical features of the embodiments of the present disclosure will not be limited thereto.

[0045] Figure 2 The structure of the NR system based on the embodiment of the present disclosure is shown. Figure 2 The embodiments of the present disclosure may be combined with various embodiments of the present disclosure.

[0046] Reference Figure 2, the next generation radio access network (NG-RAN) may include a BS 20 that provides user plane and control plane protocol terminations to the UE 10. For example, the BS 20 may include a next generation Node B (gNB) and / or an evolved Node B (eNB). For example, the UE 10 may be fixed or mobile and may be referred to as other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a mobile terminal (MT), a wireless device, etc. For example, the BS may be referred to as a fixed station that communicates with the UE 10 and may be referred to as other terms such as a base transceiver system (BTS), an access point (AP), etc.

[0047] Figure 2 The embodiment of the present invention illustrates a case where only gNB is included. BS 20 may be connected to each other via an Xn interface. BS 20 may be connected to each other via a fifth generation (5G) core network (5GC) and an NG interface. More specifically, BS 20 may be connected to an access and mobility management function (AMF) 30 via an NG-C interface, and may be connected to a user plane function (UPF) 30 via an NG-U interface.

[0048] The radio interface protocol layer between the UE and the network can be classified into the first layer (L1), the second layer (L2), and the third layer (L3) based on the lower three layers of the open system interconnection (OSI) model known in the communication system. Among them, the physical (PHY) layer belonging to the first layer provides an information transmission service using a physical channel, and the radio resource control (RRC) layer located at the third layer controls the radio resources between the UE and the network. To this end, the RRC layer exchanges RRC messages between the UE and the BS layer.

[0049] Figure 3 A radio protocol architecture according to an embodiment of the present disclosure is shown. Figure 3 The embodiments of can be combined with various embodiments of the present disclosure. Specifically, Figure 3 (a) in FIG. 1 shows a radio protocol stack for a user plane of Uu communication, and Figure 3 (b) in FIG. 5 shows the radio protocol stack of the control plane for Uu communication. Figure 3 (c) in FIG. 1 shows a radio protocol stack of a user plane for SL communication, and Figure 3 (d) in FIG. 5 shows the radio protocol stack of the control plane for SL communication.

[0050] Reference Figure 3, the physical layer provides information transfer services to the upper layer through the physical channel. The physical layer is connected to the media access control (MAC) layer, which is the upper layer of the physical layer, through the transport channel. Data is transferred between the MAC layer and the physical layer through the transport channel. The transport channel is classified according to how the data is transmitted through the radio interface and what characteristics of the data it transmits.

[0051] Data is transmitted through a physical channel between different physical layers (ie, a PHY layer of a transmitter and a PHY layer of a receiver). The physical channel may be modulated using an Orthogonal Frequency Division Multiplexing (OFDM) scheme, and uses time and frequency as radio resources.

[0052] The MAC layer provides services to the Radio Link Control (RLC) layer via logical channels, which is a higher layer of the MAC layer. The MAC layer provides a function of mapping multiple logical channels to multiple transport channels. The MAC layer also provides a function of logical channel multiplexing by mapping multiple logical channels to a single transport channel. The MAC layer provides data transmission services through logical channels.

[0053] The RLC layer performs concatenation, segmentation, and reassembly of Radio Link Control Service Data Units (RLC SDUs). In order to ensure different Quality of Service (QoS) required by Radio Bearers (RBs), the RLC layer provides three types of operation modes, namely, Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM). AM RLC provides error correction through Automatic Repeat Request (ARQ).

[0054] The Radio Resource Control (RRC) layer is defined only in the control plane. The RRC layer is used to control logical channels, transport channels, and physical channels associated with the configuration, reconfiguration, and release of RBs. RBs are logical paths for data transmission between UEs and networks provided by the first layer (i.e., the physical layer or PHY layer) and the second layer (i.e., the MAC layer, the RLC layer, the packet data convergence protocol (PDCP) layer, and the service data adaptation protocol (SDAP) layer).

[0055] The functions of the Packet Data Convergence Protocol (PDCP) in the user plane include the transmission of user data, header compression and encryption. The functions of the Packet Data Convergence Protocol (PDCP) in the control plane include the transmission and encryption / integrity protection of control plane data.

[0056] The Service Data Adaptation Protocol (SDAP) layer is defined only in the user plane. The SDAP layer performs mapping between Quality of Service (QoS) flows and Data Radio Bearers (DRBs) and QoS Flow ID (QFI) marking in both DL and UL packets.

[0057] Configuration of RB means a process for specifying radio protocol layers and channel attributes to provide a specific service and for determining corresponding detailed parameters and operation methods. RBs can then be classified into two types, namely, signaling radio bearers (SRBs) and data radio bearers (DRBs). SRBs are used as a path for sending RRC messages in the control plane, and DRBs are used as a path for sending user data in the user plane.

[0058] When the RRC connection is established between the RRC layer of the UE and the RRC layer of the E-UTRAN, the UE is in the RRC connected (RRC_CONNECTED) state, otherwise the UE can be in the RRC idle (RRC_IDLE) state. In the case of NR, the RRC inactive (RRC_INACTIVE) state is additionally defined, and the UE in the RRC_INACTIVE state can maintain the connection with the core network and release its connection with the BS.

[0059] The downlink transmission channels for sending (or transmitting) data from the network to the UE include a broadcast channel (BCH) for sending system information and a downlink shared channel (SCH) for sending other user services or control messages. The services or control messages of downlink multicast or broadcast services can be sent via the downlink SCH or can be sent via a separate downlink multicast channel (MCH). In addition, the uplink transmission channels for sending (or transmitting) data from the UE to the network include a random access channel (RACH) for sending initial control messages and an uplink shared channel (SCH) for sending other user services or control messages.

[0060] Examples of logical channels belonging to a higher layer of a transport channel and mapped to a transport channel may include a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), a multicast traffic channel (MTCH), etc.

[0061] Figure 4 The structure of a radio frame of NR based on an embodiment of the present disclosure is shown. Figure 4 The embodiments of the present disclosure may be combined with various embodiments of the present disclosure.

[0062] Reference Figure 4 In NR, a radio frame can be used to perform uplink and downlink transmissions. The length of a radio frame is 10ms and can be defined as consisting of two half frames (HF). A half frame can include five 1ms subframes (SF). A subframe (SF) can be divided into one or more time slots, and the number of time slots within a subframe can be determined according to the subcarrier spacing (SCS). Each time slot can include 12 or 14 OFDM (A) symbols depending on the cyclic prefix (CP).

[0063] When a normal CP is used, each time slot may include 14 symbols. When an extended CP is used, each time slot may include 12 symbols. Herein, a symbol may include an OFDM symbol (or a CP-OFDM symbol) and a single carrier-FDMA (SC-FDMA) symbol (or a discrete Fourier transform spread OFDM (DFT-s-OFDM) symbol).

[0064] Table 1 shown below shows the number of symbols (N) per time slot according to the SCS configuration (u) in the case of adopting a normal CP. slot symb ), the number of time slots per frame (N frame,u slot ) and the number of time slots per subframe (N subframe,u slot ).

[0065] [Table 1]

[0066] <![CDATA[SCS(15*2 u )]]> <![CDATA[N slot symb ]]> <![CDATA[N frame,u slot ]]> <![CDATA[N subframe,u slot ]]> 15KHz(u=0) 14 10 1 30KHz(u=1) 14 20 2 60KHz(u=2) 14 40 4 120KHz(u=3) 14 80 8 240KHz(u=4) 14 160 16

[0067] Table 2 shows an example of the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to the SCS in the case of using the extended CP.

[0068] [Table 2]

[0069] <![CDATA[SCS(15*2 u )]]> <![CDATA[N slot symb ]]> <![CDATA[N frame,u slot ]]> <![CDATA[N subframe,u slot ]]> 60KHz(u=2) 12 40 4

[0070] In the NR system, OFDM (A) parameter sets (e.g., SCS, CP length, etc.) between multiple cells integrated into one UE may be configured differently. Therefore, the (absolute time) duration (or interval) of a time resource (e.g., a subframe, a time slot, or a TTI) (collectively referred to as a time unit (TU) for simplicity) consisting of the same number of symbols may be configured differently in the integrated cells.

[0071] In NR, multiple parameter sets or SCSs can be supported to support various 5G services. For example, with an SCS of 15kHz, a wide range of traditional cellular bands can be supported, and with an SCS of 30kHz / 60kHz, dense cities, lower latency, and wider carrier bandwidths can be supported. With an SCS of 60kHz or higher, bandwidths greater than 24.25GHz can be used to overcome phase noise.

[0072] The NR frequency band may be defined as two different types of frequency ranges. The two different types of frequency ranges may be FR1 and FR2. The values ​​of the frequency ranges may be changed (or varied), for example, the two different types of frequency ranges may be as shown in Table 3 below. Among the frequency ranges used in the NR system, FR1 may mean "a range below 6 GHz", and FR2 may mean "a range above 6 GHz", and may also be referred to as millimeter wave (mmW).

[0073] [Table 3]

[0074] Frequency range specification Corresponding frequency range Subcarrier Spacing (SCS) FR1 450MHz–6000MHz 15, 30, 60kHz FR2 24250MHz–52600MHz 60, 120, 240kHz

[0075] As described above, the value of the frequency range in the NR system may be changed (or varied). For example, as shown in Table 4 below, FR1 may include a bandwidth in the range of 410 MHz to 7125 MHz. More specifically, FR1 may include frequency bands of 6 GHz (or 5850, 5900, 5925 MHz, etc.) and higher. For example, the frequency bands of 6 GHz (or 5850, 5900, 5925 MHz, etc.) and higher included in FR1 may include unlicensed frequency bands. Unlicensed frequency bands may be used for various purposes, for example, unlicensed frequency bands are used for vehicle-specific communications (e.g., autonomous driving).

[0076] [Table 4]

[0077] Frequency range specification Corresponding frequency range Subcarrier Spacing (SCS) FR1 410MHz–7125MHz 15, 30, 60kHz FR2 24250MHz–52600MHz 60, 120, 240kHz

[0078] Figure 5 The structure of the time slot of the NR frame based on the embodiment of the present disclosure is shown. Figure 5 The embodiments of the present disclosure may be combined with various embodiments of the present disclosure.

[0079] Reference Figure 5 , a time slot includes multiple symbols in the time domain. For example, in the case of normal CP, one time slot may include 14 symbols. For example, in the case of extended CP, one time slot may include 12 symbols. Alternatively, in the case of normal CP, one time slot may include 7 symbols. However, in the case of extended CP, one time slot may include 6 symbols.

[0080] A carrier includes multiple subcarriers in the frequency domain. A resource block (RB) can be defined as multiple consecutive subcarriers in the frequency domain (e.g., 12 subcarriers). A bandwidth part (BWP) can be defined as multiple consecutive (physical) resource blocks ((P)RBs) in the frequency domain, and a BWP can correspond to a parameter set (e.g., SCS, CP length, etc.). A carrier can include up to N BWPs (e.g., 5 BWPs). Data communication can be performed via enabled BWPs. Each element can be referred to as a resource element (RE) in a resource grid, and a complex symbol can be mapped to each element.

[0081] Hereinafter, the bandwidth part (BWP) and the carrier will be described in detail.

[0082] A BWP may be a contiguous set of physical resource blocks (PRBs) within a given parameter set. A PRB may be selected from a contiguous set of common resource blocks (CRBs) for a given parameter set on a given carrier.

[0083] For example, the BWP may be at least any one of an active BWP, an initial BWP, and / or a default BWP. For example, the UE may not monitor the downlink radio link quality in a DL BWP other than the active DL BWP on the primary cell (PCell). For example, the UE may not receive a PDCCH, a physical downlink shared channel (PDSCH), or a channel state information-reference signal (CSI-RS) (excluding RRM) other than the active DL BWP. For example, the UE may not trigger a channel state information (CSI) report for an inactive DL BWP. For example, the UE may not send a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH) outside the active UL BWP. For example, in the case of a downlink, the initial BWP may be given as a set of contiguous RBs for a remaining minimum system information (RMSI) control resource set (CORESET) (configured by a physical broadcast channel (PBCH)). For example, in the case of an uplink, the initial BWP may be given by a system information block (SIB) for a random access procedure. For example, a default BWP may be configured by a higher layer. For example, the initial value of the default BWP may be the initial DL BWP.To save energy, if the UE cannot detect downlink control information (DCI) during a specified period, the UE may switch the active BWP of the UE to the default BWP.

[0084] In addition, a BWP can be defined for SL. The same SL BWP can be used in transmission and reception. For example, a transmitting UE can send a SL channel or a SL signal on a specific BWP, and a receiving UE can receive a SL channel or a SL signal on a specific BWP. In a licensed carrier, the SL BWP can be defined separately from the Uu BWP, and the SL BWP can have configuration signaling separate from the Uu BWP. For example, the UE can receive a configuration for the SL BWP from the BS / network. For example, the UE can receive a configuration for the Uu BWP from the BS / network. SLBWP is (pre-)configured in the carrier for out-of-coverage NR V2X UEs and RRC_IDLE UEs. For UEs in RRC_CONNECTED mode, at least one SL BWP can be enabled in the carrier.

[0085] Figure 6 An example of a BWP based on an embodiment of the present disclosure is shown. Figure 6 The embodiments of can be combined with various embodiments of the present disclosure. Figure 6 In an implementation manner, the number of BWPs is 3.

[0086] Reference Figure 6 , a common resource block (CRB) may be a carrier resource block numbered from one end of a carrier frequency band to the other end thereof. Additionally, a PRB may be a resource block numbered within each BWP. Point A may indicate a common reference point of a resource block grid.

[0087] It can be obtained by point A, the offset relative to point A (N start BWP ) and bandwidth (N size BWP ) to configure the BWP. For example, point A can be an external reference point of the PRBs of the carrier, and subcarrier 0 of all parameter sets (e.g., all parameter sets supported by the network on the corresponding carrier) are aligned in point A. For example, the offset can be the PRB distance between the lowest subcarrier within a given parameter set and point A. For example, the bandwidth can be the number of PRBs within a given parameter set.

[0088] Hereinafter, V2X or SL communication will be described.

[0089] The side link synchronization signal (SLSS) may include a primary side link synchronization signal (PSSS) and a secondary side link synchronization signal (SSSS) as SL specific sequences. The PSSS may be referred to as a side link primary synchronization signal (S-PSS), and the SSSS may be referred to as a side link secondary synchronization signal (S-SSS). For example, an M sequence of length 127 may be used for the S-PSS, and a Gold sequence of length 127 may be used for the S-SSS. For example, the UE may use the S-PSS for initial signal detection and synchronization acquisition. For example, the UE may use the S-PSS and the S-SSS for acquisition of detailed synchronization and for detection of a synchronization signal ID.

[0090] The physical sidelink broadcast channel (PSBCH) can be a (broadcast) channel for sending default (system) information, which the UE must first know before SL signal transmission / reception. For example, the default information can be information related to SLSS, duplex mode (DM), time division duplex (TDD) uplink / downlink (UL / DL) configuration, information related to resource pool, type of application related to SLSS, subframe offset, broadcast information, etc. For example, in order to evaluate PSBCH performance, in NR V2X, the payload size of PSBCH can be 56 bits, including a 24-bit cyclic redundancy check (CRC).

[0091] S-PSS, S-SSS, and PSBCH may be included in a block format that supports periodic transmission (e.g., SL synchronization signal (SS) / PSBCH block, hereinafter, sidelink synchronization signal block (S-SSB)). The S-SSB may have the same parameter set (i.e., SCS and CP length) as the physical sidelink control channel (PSCCH) / physical sidelink shared channel (PSSCH) in the carrier, and the transmission bandwidth may exist within a (pre-) configured sidelink (SL) BWP. For example, the S-SSB may have a bandwidth of 11 resource blocks (SBs). For example, the PSBCH may exist across 11 RBs. In addition, the frequency position of the S-SSB may be (pre-) configured. Therefore, the UE does not have to perform hypothesis detection at the frequency to discover the S-SSB in the carrier.

[0092] Figure 7 A UE performing V2X or SL communication according to an embodiment of the present disclosure is shown. Figure 7 The embodiments of the present disclosure may be combined with various embodiments of the present disclosure.

[0093] Reference Figure 7In V2X or SL communication, the term "UE" may generally refer to a user's UE. However, if a network device such as a BS transmits / receives a signal according to a communication scheme between UEs, the BS may also be regarded as a type of UE. For example, UE 1 may be a first device 100, and UE 2 may be a second device 200.

[0094] For example, UE 1 may select a resource unit corresponding to a specific resource in a resource pool meaning a set of resource series. In addition, UE 1 may send an SL signal by using the resource unit. For example, a resource pool in which UE 1 can send a signal may be configured to UE 2 as a receiving UE, and a signal of UE 1 may be detected in the resource pool.

[0095] Herein, if UE 1 is within the connection range of the BS, the BS may inform the resource pool to UE 1. Otherwise, if UE 1 is out of the connection range of the BS, another UE may inform UE 1 of the resource pool, or UE 1 may use a preconfigured resource pool.

[0096] Generally, a resource pool may be configured in units of multiple resources, and each UE may select one or more units of resources to use in its SL signaling.

[0097] Hereinafter, resource allocation in SL will be described.

[0098] Figure 8 A process of performing V2X or SL communication based on a transmission mode by a UE according to an embodiment of the present disclosure is shown. Figure 8 The embodiments of the present disclosure 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 ease of explanation, in LTE, the transmission mode may be referred to as an LTE transmission mode. In NR, the transmission mode may be referred to as an NR resource allocation mode.

[0099] For example, Figure 8 (a) in FIG. 1 shows UE operations related to LTE transmission mode 1 or LTE transmission mode 3. Alternatively, for example, Figure 8 (a) in FIG. 1 shows UE operations related to NR resource allocation mode 1. For example, LTE transmission mode 1 may be applied to conventional SL communication, and LTE transmission mode 3 may be applied to V2X communication.

[0100] For example, Figure 8 (b) in FIG. 4 shows UE operations related to LTE transmission mode 2 or LTE transmission mode 4. Alternatively, for example, Figure 8 (b) in FIG. 1 shows UE operation related to NR resource allocation mode 2.

[0101] Reference Figure 8 (a) in which, in LTE transmission mode 1, LTE transmission mode 3, or NR resource allocation mode 1, the BS may schedule SL resources to be used by the UE for SL transmission. For example, the BS may perform resource scheduling for UE 1 through PDCCH (e.g., downlink control information (DCI)) or RRC signaling (e.g., configuration grant type 1 or configuration grant type 2), and UE 1 may perform V2X or SL communication for UE 2 according to the resource scheduling. For example, UE 1 may send sidelink control information (SCI) to UE 2 through a physical sidelink control channel (PSCCH), and thereafter send data based on the SCI to UE 2 through a physical sidelink shared channel (PSSCH).

[0102] Reference Figure 8 (b) in the figure, in LTE transmission mode 2, LTE transmission mode 4 or NR resource allocation mode 2, the UE can determine the SL transmission resources within the SL resources configured by the BS / network or the pre-configured SL resources. For example, the configured SL resources or the pre-configured SL resources can be a resource pool. For example, the UE can autonomously select or schedule resources for SL transmission. For example, the UE can perform SL communication by autonomously selecting resources in the configured resource pool. For example, the UE can autonomously select resources within the selection window by performing sensing and resource (re)selection processes. For example, sensing can be performed in units of subchannels. In addition, UE 1 that has autonomously selected resources in the resource pool can send SCI to UE 2 via PSCCH, and thereafter data based on the SCI can be sent to UE 2 via PSSCH.

[0103] Fig. 9 Three types of broadcasts based on embodiments of the present disclosure are shown. Fig. 9 The embodiments of can be combined with various embodiments of the present disclosure. Specifically, Fig. 9 (a) shows broadcast type SL communication, Fig. 9 (b) in FIG. 4 shows unicast type SL communication, and Fig. 9 (c) shows multicast SL communication. In the case of unicast SL communication, the UE can perform one-to-one communication with another UE. In the case of multicast SL transmission, the UE can perform SL communication with one or more UEs in the group to which the UE belongs. In various embodiments of the present disclosure, SL groupcast communication can be replaced by SL multicast communication, SL one-to-many communication, etc.

[0104] Hereinafter, side link (SL) congestion control will be described.

[0105] If the UE autonomously determines the SL transmission resources, the UE also autonomously determines the size and frequency of use of the resources for use by the UE. Of course, due to constraints from the network, etc., the use of resource sizes or usage frequencies greater than or equal to a certain level may be limited. However, if all UEs use a relatively large amount of resources in a situation where many UEs are concentrated in a specific area at a specific time, the overall performance may be significantly degraded due to mutual interference.

[0106] Therefore, the UE may need to observe the channel situation. If it is determined that an excessive amount of resources are consumed, it is preferred that the UE autonomously reduce the use of resources. In the present disclosure, this can be defined as congestion control (CR). For example, the UE can determine whether the energy measured in the unit time / frequency resource is greater than or equal to a specific level, and can adjust the amount and frequency of use of its transmission resources based on the ratio of the unit time / frequency resources in which the energy greater than or equal to the specific level is observed. In the present disclosure, the ratio of the time / frequency resources in which the energy greater than or equal to the specific level is observed can be defined as the channel busy rate (CBR). The UE can measure the CBR of the channel / frequency. In addition, the UE can send the measured CBR to the network / BS.

[0107] Fig.10 The resource unit used for CBR measurement according to the embodiment of the present disclosure is shown. Fig.10 The embodiments of the present disclosure may be combined with various embodiments of the present disclosure.

[0108] Reference Fig.10 As a result of the UE measuring RSSI based on the subchannel within a specific period (e.g., 100 ms), the CBR may indicate the number of subchannels in which the measurement result value of the received signal strength indicator (RSSI) has a value greater than or equal to a preconfigured threshold. Alternatively, the CBR may indicate the ratio of subchannels having a value greater than or equal to the preconfigured threshold among the subchannels within a specific duration. For example, Fig.10 In an embodiment of the present invention, if it is assumed that a shadowed subchannel is a subchannel having a value greater than or equal to a preconfigured threshold, the CBR may represent a ratio of shadowed subchannels within a 100 ms period. In addition, the UE may report the CBR to the BS.

[0109] In addition, congestion control that takes into account the priority of the service (e.g., packet) may be necessary. To this end, for example, the UE may measure the channel occupancy ratio (CR). Specifically, the UE may measure the CBR, and the UE may determine the maximum value CRlimitk of the channel occupancy k (CRk) that may be occupied by the service corresponding to each priority (e.g., k) based on the CBR. For example, the UE may derive the maximum value CRlimitk of the channel occupancy related to the priority of each service based on a predetermined table of CBR measurements. For example, in the case of a service with a relatively high priority, the UE may derive a relatively large maximum value of the channel occupancy. Thereafter, the UE may perform congestion control by limiting the sum of the channel occupancies of services whose priority k is lower than i to a value less than or equal to a specific value. Based on this method, the channel occupancy may be more strictly limited for services with relatively low priority.

[0110] In addition to this, the UE can perform SL congestion control by using adjusting the transmit power level, discarding packets, determining whether to perform retransmission, adjusting the transmit RB size (MCS coordination), etc.

[0111] Hereinafter, a hybrid automatic repeat request (HARQ) process will be described.

[0112] In the case of SL unicast and multicast, HARQ feedback and HARQ combining in the physical layer can be supported. For example, in the case where the receiving UE operates in resource allocation mode 1 or 2, the receiving UE can receive PSSCH from the transmitting UE, and the receiving UE can send HARQ feedback corresponding to PSSCH to the transmitting UE through the physical sidelink feedback channel (PSFCH) using the sidelink feedback control information (SFCI) format.

[0113] For example, SL HARQ feedback may be enabled for unicast. In this case, in non-code block group (non-CBG) operation, the receiving UE may decode the PSCCH targeted to the receiving UE, and when the receiving UE successfully decodes the transport block associated with the PSCCH, the receiving UE may generate a HARQ-ACK. Thereafter, the receiving UE may send the HARQ-ACK to the transmitting UE. Conversely, after the receiving UE decodes the PSCCH targeted to the receiving UE, if the receiving UE fails to successfully decode the transport block associated with the PSCCH, the receiving UE may generate a HARQ-NACK, and the receiving UE may send the HARQ-NACK to the transmitting UE.

[0114] For example, SL HARQ feedback may be enabled for multicast.For example, during non-CBG, two different types of HARQ feedback options may be supported for multicast.

[0115] (1) Multicast Option 1: After decoding the PSCCH targeted at the receiving UE, if the receiving UE fails to decode the transport block associated with the PSCCH, the receiving UE may send a HARQ-NACK to the transmitting UE via the PSFCH. Conversely, when the receiving UE decodes the PSCCH targeted at the receiving UE and when the receiving UE successfully decodes the transport block associated with the PSCCH, the receiving UE does not send a HARQ-ACK to the transmitting UE.

[0116] (2) Multicast Option 2: After decoding the PSCCH targeted at the receiving UE, if the receiving UE fails to decode the transport block associated with the PSCCH, the receiving UE may send a HARQ-NACK to the transmitting UE via the PSFCH. Also, when the receiving UE decodes the PSCCH targeted at the receiving UE and when the receiving UE successfully decodes the transport block associated with the PSCCH, the receiving UE may send a HARQ-ACK to the transmitting UE via the PSFCH.

[0117] For example, if multicast option 1 is used in SL HARQ feedback, all UEs performing multicast communication can share PSFCH resources. For example, UEs belonging to the same group can send HARQ feedback by using the same PSFCH resources.

[0118] For example, if multicast option 2 is used in SL HARQ feedback, each UE performing multicast communication may use different PSFCH resources for HARQ feedback transmission. For example, UEs belonging to the same group may send HARQ feedback by using different PSFCH resources.

[0119] For example, when SL HARQ feedback is enabled for groupcast, the receiving UE may determine whether to send HARQ feedback to the transmitting UE based on transmit-receive (TX-RX) distance and / or reference signal received power (RSRP).

[0120] For example, in multicast option 1, in the case of HARQ feedback based on TX-RX distance, if the TX-RX distance is less than or equal to the communication range requirement, the receiving UE may send HARQ feedback in response to the PSSCH to the transmitting UE. Otherwise, if the TX-RX distance is greater than the communication range requirement, the receiving UE may not send HARQ feedback in response to the PSSCH to the transmitting UE. For example, the transmitting UE may inform the receiving UE of the location of the transmitting UE via the SCI associated with the PSSCH. For example, the SCI associated with the PSSCH may be a second SCI. For example, the receiving UE may estimate or obtain the TX-RX distance based on the location of the receiving UE and the location of the transmitting UE. For example, the receiving UE may decode the SCI associated with the PSSCH, and therefore may know the communication range requirement for the PSSCH.

[0121] For example, in the case of resource allocation mode 1, the time (offset) between PSFCH and PSSCH can be configured or pre-configured. In the case of unicast and multicast, if retransmission is required on the SL, it can be indicated to the BS by the UE within the coverage area using PUCCH. The sending UE can send an indication to the serving BS of the sending UE in the form of a scheduling request (SR) / buffer status report (BSR) instead of a HARQ ACK / NACK. In addition, even if the BS does not receive the indication, the BS can schedule SL retransmission resources for the UE. For example, in the case of resource allocation mode 2, the time (offset) between PSFCH and PSSCH can be configured or pre-configured.

[0122] For example, from the perspective of UE transmission in a carrier, for a PSFCH format for SL in a time slot, TDM between PSCCH / PSSCH and PSFCH may be allowed. For example, a sequence-based PSFCH format with a single symbol may be supported. Herein, the single symbol may not be the AGC duration. For example, a sequence-based PSFCH format may be applied to unicast and multicast.

[0123] For example, in a time slot associated with a resource pool, the PSFCH resource may be periodically configured for N time slot durations, or may be preconfigured. For example, N may be configured as one or more values ​​greater than or equal to 1. For example, N may be 1, 2, or 4. For example, HARQ feedback for transmissions in a specific resource pool may be sent over the PSFCH only on the specific resource pool.

[0124] For example, if a transmitting UE sends a PSSCH to a receiving UE across time slot #x to time slot #n, the receiving UE may send HARQ feedback in response to the PSSCH to the transmitting UE in time slot #(N+A). For example, time slot #(N+A) may include PSFCH resources. Herein, for example, A may be a minimum integer greater than or equal to K. For example, K may be the number of logical time slots. In this case, K may be the number of time slots in a resource pool. Alternatively, for example, K may be the number of physical time slots. In this case, K may be the number of time slots inside or outside the resource pool.

[0125] For example, if the receiving UE sends HARQ feedback on the PSFCH resource in response to a PSSCH sent by the transmitting UE to the receiving UE, the receiving UE may determine the frequency domain and / or code domain of the PSFCH resource based on an implicit mechanism in the configured resource pool. For example, the receiving UE may determine the frequency domain and / or code domain of the PSFCH resource based on at least one of a timeslot index associated with the PSCCH / PSSCH / PSFCH, a subchannel associated with the PSCCH / PSSCH, or an identifier for each receiving UE in a group for identifying HARQ feedback based on multicast option 2. Additionally / alternatively, for example, the receiving UE may determine the frequency domain and / or code domain of the PSFCH resource based on at least one of SL RSRP, SINR, L1 source ID, and / or location information.

[0126] For example, if HARQ feedback transmission via the UE's PSFCH overlaps with HARQ feedback reception via the PSFCH, the UE may select either HARQ feedback transmission via the PSFCH or HARQ feedback reception via the PSFCH based on a priority rule. For example, the priority rule may be based at least on a priority indication of the associated PSCCH / PSSCH.

[0127] For example, if HARQ feedback transmissions by UEs via PSFCH overlap for multiple UEs, the UEs may select a specific HARQ feedback transmission based on a priority rule. For example, the priority rule may be based on the lowest priority indication of the related PSCCH / PSSCH.

[0128] In addition, in the present disclosure, a transmitting UE (i.e., a TX UE) may be a UE that transmits data to a (target) receiving UE (i.e., a RX UE). For example, the TX UE may be a UE that performs PSCCH transmission and / or PSSCH transmission. For example, the TX UE may be a UE that sends a SL CSI-RS and / or a SL CSI report request indicator to a (target) RX UE. For example, the TX UE may be a UE that sends a (predefined) reference signal (e.g., a PSSCH demodulation reference signal (DM-RS)) and / or a SL (L1) RSRP report request indicator to a (target) RX UE for SL (L1) RSRP measurement. For example, the TX UE may be a UE that sends a (control) channel (e.g., PSCCH, PSSCH, etc.) and / or a reference signal on a (control) channel (e.g., DM-RS, CSI-RS) for SL radio link monitoring (RLM) operation and / or SL radio link failure (RLF) operation of a (target) RX UE.

[0129] In addition, in the present disclosure, a receiving UE (i.e., RX UE) may be a UE that sends SL HARQ feedback to a transmitting UE (i.e., TX UE) based on whether decoding of data received from the TX UE is successful and / or whether detection / decoding of a PSCCH (related to PSSCH scheduling) sent by the TX UE is successful. For example, the RX UE may be a UE that performs SL CSI transmission to the TX UE based on the SL CSI-RS and / or SL CSI report request indicator received from the TX UE. For example, the RX UE may be a UE that sends to the TX UE a SL (L1) RSRP measurement value measured based on a (predefined) reference signal and / or SL (L1) RSRP report request indicator received from the TX UE. For example, the RX UE may be a UE that sends data of the RX UE to the TX UE. For example, the RX UE may be a UE that performs SL RLM operation and / or SL RLF operation based on a (preconfigured) (control) channel and / or a reference signal on a (control) channel received from the TX UE.

[0130] In addition, in the present disclosure, the TX UE may send all or part of the following information to the RX UE through the SCI. Herein, for example, the TX UE may send all or part of the following information to the RX UE through the first SCI and / or the second SCI.

[0131] -PSSCH (and / or PSCCH) related resource allocation information (e.g., location / number of time / frequency resources, resource reservation information (e.g., period))

[0132] -SL CSI report request indicator or SL (L1) RSRP (and / or SL (L1) RSRQ and / or SL (L1) RSSI) report request indicator

[0133] -SL CSI transmission indicator (or SL (L1) RSRP (and / or SL (L1) RSRQ and / or SL (L1) RSSI) information transmission indicator)) (on PSSCH)

[0134] - Modulation and Coding Scheme (MCS) information

[0135] - Transmit power information

[0136] - L1 destination ID information and / or L1 source ID information

[0137] -SL HARQ process ID information

[0138] -New Data Indicator (NDI) information

[0139] - Redundancy Version (RV) information

[0140] -QoS information (for example, priority information) (related to the transmission service / packet)

[0141] - Information on the number of antenna ports used for (transmitting) SL CSI-RS or SL CSI-RS transmission indicator

[0142] - The location (or distance range) information of the target RX UE (for which SL HARQ feedback is requested) or the TX UE location information

[0143] -Reference signal (e.g., DM-RS, etc.) information related to decoding and / or channel estimation of data to be sent through the PSSCH. For example, the reference signal information may be information related to a pattern of (time-frequency) mapping resources of the DM-RS, rank information, antenna port index information, information about the number of antenna ports, etc.

[0144] In addition, in the present disclosure, for example, the PSCCH may be replaced / replaced with at least one of the SCI, the first SCI (first-level SCI), and / or the second SCI (second-level SCI), or vice versa. For example, the SCI may be replaced / replaced with at least one of the PSCCH, the first SCI, and / or the second SCI, or vice versa. For example, the PSSCH may be replaced / replaced with the second SCI and / or the PSCCH, or vice versa.

[0145] In addition, in the present disclosure, for example, if the SCI configuration field is divided into two groups in consideration of the (relatively) high SCI payload size, the SCI including the first SCI configuration field group may be referred to as the first SCI or the first-level SCI, and the SCI including the second SCI configuration field group may be referred to as the second SCI or the second-level SCI. For example, the first SCI and the second SCI may be sent via different channels. For example, the transmitting UE may send the first SCI to the receiving UE via the PSCCH. For example, the second SCI may be sent to the receiving UE via the (independent) PSCCH, or may be sent in a piggyback manner with the data via the PSSCH.

[0146] In addition, in the present disclosure, for example, "configuration / configured" or "definition / defined" may refer to (pre) configuration from a base station or a network. For example, "configuration / configured" or "definition / defined" may refer to (pre) configuration from a base station or a network for each resource pool. For example, a base station or a network may send information related to "configuration" or "definition" to a UE. For example, a base station or a network may send information related to "configuration" or "definition" to a UE via predefined signaling. For example, the predefined signaling may include at least one of RRC signaling, MAC signaling, PHY signaling, and / or SIB.

[0147] In addition, in the present disclosure, for example, "configuration / configured" or "definition / defined" may refer to being specified or configured through pre-configuration signaling between UEs. For example, information related to "configuration" or "definition" may be sent or received through pre-configuration signaling between UEs. For example, the pre-defined signaling may include at least one of RRC signaling, MAC signaling, PHY signaling, and / or SIB.

[0148] In addition, in the present disclosure, for example, a resource block (RB) may be replaced / replaced with a subcarrier, or vice versa. For example, a packet or service may be replaced / replaced with a transport block (TB) or a media access control protocol data unit (MAC PDU) according to a transport layer, or vice versa. For example, a code block group (CBG) may be replaced / replaced with a TB, or vice versa. For example, a source ID may be replaced / replaced with a destination ID, or vice versa. For example, an L1 ID may be replaced / replaced with an L2 ID, or vice versa. For example, an L1 ID may be an L1 source ID or an L1 destination ID. For example, an L2 ID may be an L2 source ID or an L2 destination ID.

[0149] Furthermore, in the present disclosure, for example, the operation of the TX UE reserving / selecting / determining retransmission resources may include the operation of the TX UE reserving / selecting / determining potential retransmission resources in which whether to actually use is determined based on the SL HARQ feedback information received from the RX UE.

[0150] Furthermore, in the present disclosure, a sub-selection window may be replaced / replaced with a selection window and / or a preconfigured number of resource sets within the selection window, or vice versa.

[0151] In addition, in the present disclosure, SL mode 1 may refer to a resource allocation method or a communication method in which a base station directly schedules SL transmission resources for a TX UE through predefined signaling (e.g., DCI or RRC message). For example, SL mode 2 may refer to a resource allocation method or a communication method in which a UE independently selects SL transmission resources from a resource pool preconfigured or configured from a base station or a network. For example, a UE that performs SL communication based on SL mode 1 may be referred to as a mode 1 UE or a mode 1 TX UE, and a UE that performs SL communication based on SL mode 2 may be referred to as a mode 2 UE or a mode 2 TX UE.

[0152] In addition, in the present disclosure, for example, a dynamic grant (DG) may be replaced / replaced with a configuration grant (CG) and / or a semi-persistent scheduling (SPS) grant, or vice versa. For example, the DG may be replaced / replaced with a combination of a CG and an SPS grant, or vice versa. For example, the CG may include at least one of a configuration grant (CG) type 1 and / or a configuration grant (CG) type 2. For example, in CG type 1, the grant may be provided via RRC signaling and may be stored as a configuration grant. For example, in CG type 2, the grant may be provided via PDCCH and may be stored or deleted as a configuration grant based on L1 signaling indicating activation or deactivation of the grant. For example, in CG type 1, the base station may allocate periodic resources to the TX UE via an RRC message. For example, in CG type 2, the base station may allocate periodic resources to the TX UE via an RRC message, and the base station may dynamically enable or deactivate the periodic resources via DCI.

[0153] In addition, in the present disclosure, a channel may be replaced / replaced with a signal, or vice versa. For example, the sending / receiving of a channel may include the sending / receiving of a signal. For example, the sending / receiving of a signal may include the sending / receiving of a channel. For example, a broadcast may be replaced / replaced with at least one of unicast, multicast, and / or broadcast, or vice versa. For example, a broadcast type may be replaced / replaced with at least one of unicast, multicast, and / or broadcast, or vice versa. For example, a broadcast or a broadcast type may include unicast, multicast, and / or broadcast.

[0154] Furthermore, in the present disclosure, a resource may be exchanged / replaced with a time slot or a symbol, or vice versa. For example, a resource may include a time slot and / or a symbol.

[0155] In addition, in the present disclosure, priority can be replaced / replaced with at least one of logical channel prioritization (LCP), latency, reliability, minimum required communication range, ProSe per-packet priority (PPPP), sidelink radio bearer (SLRB), QoS profile, QoS parameters and / or requirements, or vice versa.

[0156] Furthermore, in the present disclosure, for example, for convenience of description, a (physical) channel used when the RX UE transmits at least one of the following information to the TX UE may be referred to as a PSFCH.

[0157] -SL HARQ feedback, SL CSI, SL (L1) RSRP

[0158] In addition, in the present disclosure, the Uu channel may include a UL channel and / or a DL channel. For example, the UL channel may include a PUSCH, a PUCCH, a sounding reference signal (SRS), etc. For example, the DL channel may include a PDCCH, a PDSCH, a PSS / SSS, etc. For example, the SL channel may include a PSCCH, a PSSCH, a PSFCH, a PSBCH, a PSSS / SSSS, etc.

[0159] In addition, in the present disclosure, the sidelink information may include at least one of a sidelink message, a sidelink packet, a sidelink service, a sidelink data, a sidelink control information and / or a sidelink transport block (TB). For example, the sidelink information may be sent via PSSCH and / or PSCCH.

[0160] Furthermore, in the present disclosure, a high priority may mean a small priority value, and a low priority may mean a large priority value. For example, Table 5 shows an example of priority.

[0161] [Table 5]

[0162] Service or logical channel Priority value Service A or Logical Channel A 1 Service B or logical channel B 2 Service C or logical channel C 3

[0163] Referring to Table 5, for example, service A or logical channel A associated with the smallest priority value may have the highest priority. For example, service C or logical channel C associated with the largest priority value may have the lowest priority.

[0164] In addition, in NR V2X communication or NR sidelink communication, the transmitting UE can reserve / select one or more transmission resources for sidelink transmission (e.g., initial transmission and / or retransmission), and the transmitting UE can send information about the location of one or more transmission resources to the receiving UE.

[0165] In addition, when performing sidelink communication, a method in which a transmitting UE reserves or predetermines transmission resources for a receiving UE may be representatively as follows.

[0166] For example, the transmitting UE may perform the reservation of transmission resources based on the chain. Specifically, for example, if the transmitting UE reserves K transmission resources, the transmitting UE may send the location information of less than K transmission resources to the receiving UE through the SCI sent to the receiving UE at any (or specific) transmission time or time resource. That is, for example, the SCI may include the location information of less than K transmission resources. Alternatively, for example, if the transmitting UE reserves K transmission resources associated with a specific TB, the transmitting UE may send the location information of less than K transmission resources to the receiving UE through the SCI sent to the receiving UE at any (or specific) transmission time or time resource. That is, the SCI may include the location information of less than K transmission resources. In this case, for example, by signaling the location information of less than K transmission resources to the receiving UE only via one SCI sent by the transmitting UE at any (or specific) transmission time or time resource, performance degradation caused by excessive increase in the payload of the SCI can be prevented.

[0167] Fig.11 A method in which a UE having reserved transmission resources notifies another UE of the transmission resources according to an embodiment of the present disclosure is shown. Fig.11 The embodiments of the present disclosure may be combined with various embodiments of the present disclosure.

[0168] Specifically, for example, Fig.11 (a) shows a method for performing chain-based resource reservation by a transmitting UE by sending / signaling location information of (maximum) 2 transmission resources to a receiving UE via one SCI in the case of a value of K=4. For example, Fig.11 (b) shows a method for performing chain-based resource reservation by a transmitting UE by sending / signaling location information of (maximum) 3 transmission resources to a receiving UE via one SCI in the case of a value of K=4. Fig.11 (a) and (b), the transmitting UE may send / signal only the location information of the fourth transmission-related resources to the receiving UE via the fourth (or last) transmission-related PSCCH. Fig.11 (a), the transmitting UE may send / signal not only the location information of the fourth transmission-related resources but also the location information of the third transmission-related resources to the receiving UE via the fourth (or last) transmission-related PSCCH. Fig.11(b), the transmitting UE may send / signal not only the location information of the fourth transmission-related resources but also the location information of the second transmission-related resources and the location information of the third transmission-related resources to the receiving UE through the fourth (or last) transmission-related PSCCH. In this case, for example, Fig.11 In (a) and (b), if the transmitting UE can send / signal only the location information of the fourth transmission-related resources to the receiving UE through the fourth (or last) transmission-related PSCCH, the transmitting UE can set or specify the field / bit of the location information of the unused or remaining transmission resources to a preconfigured value (e.g., 0). Fig.11 In (a) and (b), if the sending UE can send / signal only the location information of the fourth transmission-related resources to the receiving UE via the fourth (or last) transmission-related PSCCH, the sending UE can set or designate the field / bit of the location information of the unused or remaining transmission resources to a preconfigured status / bit value indicating / indicating the last transmission (among the 4 transmissions).

[0169] In addition, for example, the transmitting UE may perform reservation of transmission resources on a block basis. Specifically, for example, if the transmitting UE reserves K transmission resources, the transmitting UE may send the location information of the K transmission resources to the receiving UE through an SCI sent to the receiving UE at any (or specific) transmission time or time resource. That is, the SCI may include the location information of the K transmission resources. For example, if the transmitting UE reserves K transmission resources associated with a specific TB, the transmitting UE may send the location information of the K transmission resources to the receiving UE through an SCI sent to the receiving UE at any (or specific) transmission time or time resource. That is, the SCI may include the location information of the K transmission resources. For example, Fig.11 (c) shows a method in which, in the case of a value of K=4, a transmitting UE performs block-based resource reservation by signaling location information of four transmission resources to a receiving UE via one SCI.

[0170] Fig.12 A case is shown in which a base station according to an embodiment of the present disclosure sends DCI related to transmission (retransmission) to a UE because the base station mistakenly recognizes ACK information sent by a TX UE as NACK information. Fig.12 The embodiments of the present disclosure may be combined with various embodiments of the present disclosure.

[0171] Reference Fig.12In step S1210, the TX UE may send a PSCCH and / or a PSSCH to the RX UE. For example, the TX UE may send a PSCCH and / or a PSSCH to the RX UE using the SL resources allocated by the base station. For example, the SL resources may be allocated to the TX UE via a dynamic grant (DG) sent by the base station. For example, the SL resources may be allocated to the TX UE via a configuration grant (CG) sent by the base station.

[0172] In step S1220, the TX UE may receive ACK information from the RX UE via the PSFCH. For example, if the RX UE successfully receives / decodes the PSCCH and / or PSSCH, the RX UE may send ACK information to the TX UE via the PSFCH. In step S1230, the TX UE may send ACK information to the base station via the PUCCH.

[0173] In step S1240, the base station may determine that the ACK information sent by the TX UE is NACK information. That is, even if the TX UE has sent ACK information to the base station, the base station may mistakenly identify the ACK information as NACK information. In this case, in step S1250, the base station may allocate additional transmission (retransmission) resources to the TX UE. For example, the base station may send a DG related to the transmission (retransmission) resource to the TX UE via DCI so as to allocate the transmission (retransmission) resource to the TX UE. For example, the base station may send a DCI including a DG related to the transmission (retransmission) resource to the TX UE so as to allocate the transmission (retransmission) resource to the TX UE. For example, the DG related to the transmission (retransmission) resource may indicate the transmission (retransmission) resource. For convenience of description, the DCI including the DG related to the transmission (retransmission) resource may be referred to as RE-TX DG DCI. For example, the RE-TX DG DCI may include an unswitched NDI and a HARQ process ID related to the ACK information sent via the PUCCH.

[0174] In addition, Fig.12 In the implementation manner, it is assumed that the TX UE sends PSCCH and / or PSSCH based on the DG and / or CG sent by the base station.

[0175] As described above, if the TX UE receives RE-TX DGDCI from the base station even though the TX UE has transmitted ACK information to the base station, the TX UE may operate based on at least one of the following options.

[0176] 1) Option 1

[0177] For example, the TX UE may not send PSCCH and / or PSSCH on the resources allocated by the RE-TX DG DCI, and the TX UE may send ACK information or NACK information to the base station through the PUCCH resources related to the RE-TX DG DCI. For example, the TX UE may not send MAC PDU or dummy information on the resources allocated by the RE-TX DG DCI, and the TX UE may send ACK information or NACK information to the base station through the PUCCH resources related to the RE-TX DG DCI. For example, the dummy information may be predefined information. For example, the MAC PDU may be a MAC PDU that the TX UE previously sent to the RX UE. For example, the MAC PDU may be a MAC PDU related to the HARQ process ID related to the ACK information sent by the TX UE to the base station through the PUCCH in step S1230.

[0178] 2) Option 2

[0179] For example, the TX UE may ignore the RE-TX DG DCI, and the TX UE may not send a MAC PDU or dummy information on the resources allocated by the RE-TX DG DCI, and the TX UE may not send ACK information or NACK information to the base station through the PUCCH resources related to the RE-TX DG DCI. For example, the TX UE may omit / skip the transmission of the MAC PDU or dummy information on the resources allocated by the RE-TX DG DCI, and the TX UE may omit / skip the transmission on the PUCCH resources related to the RE-TX DG DCI. For example, the dummy information may be predefined information. For example, the MAC PDU may be a MAC PDU that the TX UE previously sent to the RX UE. For example, the MAC PDU may be a MAC PDU related to the HARQ process ID related to the ACK information sent by the TX UE to the base station through the PUCCH in step S1230.

[0180] For example, in Option 1 and / or Option 2, the TX UE may ignore / discard the grant related to the RE-TX DG DCI. For example, in Option 1 and / or Option 2, there may be no new packets to be sent in the buffer of the TX UE (e.g., no MAC PDU). For example, in Option 1 and / or Option 2, there may be no remaining data in the buffer of the TX UE. For example, in Option 1 and / or Option 2, there may be no (new) MAC PDU to be generated / sent by the TX UE. For example, in Option 1 and / or Option 2, the TX UE may have flushed the (previous) buffer / data related to the HARQ process indicated by the RE-TX DG DCI.

[0181] 3) Option 3

[0182] For example, the TX UE may send PSCCH and / or PSSCH on resources allocated by RE-TX DG DCI, and the TX UE may send ACK information or NACK information to the base station through PUCCH resources related to the RE-TX DG DCI. For example, the TX UE may send MAC PDU or dummy information on resources allocated by RE-TX DG DCI, and the TX UE may send ACK information or NACK information to the base station through PUCCH resources related to the RE-TX DG DCI. For example, the dummy information may be predefined information. For example, the MAC PDU may be a MAC PDU that the TX UE previously sent to the RX UE. For example, the MAC PDU may be a MAC PDU related to a HARQ process ID related to the ACK information sent by the TX UE to the base station through the PUCCH in step S1230.

[0183] Hereinafter, in the case where the TX UE operates based on Option 3, the operation of the TX UE will be described in detail. For example, if the TX UE sends PSCCH and / or PSSCH to the RX UE on resources allocated by RE-TX DG DCI, the TX UE may set the HARQ feedback request field included in the SCI related to the PSCCH and / or PSSCH to "DISABLED". For example, if the TX UE sends PSCCH and / or PSSCH to the RX UE on resources allocated by RE-TX DG DCI, the TX UE may set the HARQ feedback request field included in the SCI related to the PSCCH and / or PSSCH to "ENABLED". For example, if the TX UE sends PSCCH and / or PSSCH to the RX UE on resources allocated by RE-TX DG DCI, the TX UE may maintain / set the NDI field value included in the SCI related to the PSCCH and / or PSSCH to be the same as the (previous) NDI field value related to the HARQ process ID related to the ACK information sent via PUCCH. For example, if the TX UE sends PSCCH and / or PSSCH to the RX UE on resources allocated by RE-TX DG DCI, the TX UE may set the SL HARQ process ID field value included in the SCI related to the PSCCH and / or PSSCH to the HARQ process ID related to the ACK information sent through the PUCCH. For example, if the TX UE sends PSCCH and / or PSSCH to the RX UE on resources allocated by RE-TX DG DCI, the TX UE may set the source ID field value and / or destination ID field value included in the SCI related to the PSCCH and / or PSSCH to the source ID field value and / or destination ID field value related to the ACK information sent through the PUCCH. For example, the source ID may be an L1 source ID, and the destination ID may be an L1 destination ID. For example, if the TX UE sends PSCCH and / or PSSCH to the RX UE on the resources allocated by the RE-TX DG DCI, the TX UE may inform the RX UE through the pre-configured field included in the SCI related to the PSCCH and / or PSSCH that the base station mistakenly identifies the ACK through the PUCCH as NACK (i.e., an ACK-TO-NACK error occurs). In the above case, if the RX UE receives a message and / or packet (e.g., a MAC PDU or dummy information) from the TX UE, the RX UE may discard the message and / or packet. For example, the RX UE does not attempt to decode the PSSCH, and the RX UE may discard the message and / or packet. For example, the RX UE may not store the message and / or packet in a buffer, and the RX UE may discard the message and / or packet.

[0184] For example, Option 1 may be restrictively applied only when there is no new packet (e.g., MAC PDU) to be sent in the buffer of the TX UE. For example, Option 1 may be restrictively applied only when there is no remaining data in the buffer of the TX UE. For example, Option 1 may be restrictively applied only when there is no (new) MAC PDU to be generated / sent by the TX UE. For example, Option 1 may be restrictively applied only when the TX UE flushes the (previous) buffer / data related to the HARQ process indicated by the RE-TX DG DCI.

[0185] For example, Option 2 may be restrictively applied only when there is no new packet (e.g., MAC PDU) to be sent in the buffer of the TX UE. For example, Option 2 may be restrictively applied only when there is no remaining data in the buffer of the TX UE. For example, Option 2 may be restrictively applied only when there is no (new) MAC PDU to be generated / sent by the TX UE. For example, Option 2 may be restrictively applied only when the TX UE flushes the (previous) buffer / data related to the HARQ process indicated by the RE-TX DG DCI.

[0186] For example, Option 3 may be restrictively applied only when there is no new packet (e.g., MAC PDU) to be sent in the buffer of the TX UE. For example, Option 3 may be restrictively applied only when there is no remaining data in the buffer of the TX UE. For example, Option 3 may be restrictively applied only when there is no (new) MAC PDU to be generated / sent by the TX UE. For example, Option 3 may be restrictively applied only when the TX UE flushes the (previous) buffer / data related to the HARQ process indicated by the RE-TX DG DCI.

[0187] For example, if option 1 is applied, and if the TX UE sends ACK information to the base station via PUCCH, the TX UE may flush the buffer (of the relevant HARQ process). For example, if option 1 is applied, and if the TX UE receives ACK information from the RX UE via PSFCH, the TX UE may flush the buffer (of the relevant HARQ process).

[0188] For example, if option 2 is applied, and if the TX UE sends ACK information to the base station via PUCCH, the TX UE may flush the buffer (of the relevant HARQ process). For example, if option 2 is applied, and if the TX UE receives ACK information from the RX UE via PSFCH, the TX UE may flush the buffer (of the relevant HARQ process).

[0189] For example, if option 3 is applied, and if the TX UE sends ACK information to the base station via PUCCH, the TX UE may flush the buffer (of the relevant HARQ process). For example, if option 3 is applied, and if the TX UE receives ACK information from the RX UE via PSFCH, the TX UE may flush the buffer (of the relevant HARQ process).

[0190] For example, if the number of transmission (retransmission) related to a specific TB reaches the maximum allowed number of retransmissions, the TX UE may be configured to report ACK information to the base station through the (associated) PUCCH resources. For example, the maximum allowed number of retransmissions may be preconfigured for the TX UE. For example, if the number of transmission (retransmission) related to a specific TB reaches the maximum allowed number of retransmissions, the TX UE may send ACK information to the base station through the (associated) PUCCH resources. Herein, for example, the TX UE may be a UE that performs SL transmission based on the CG sent by the base station. Considering the above embodiments, the TX UE may send ACK information to the base station in the following situations.

[0191] - First case: If the number of transmission (retransmission) reaches the maximum allowed number of retransmissions, the TX UE may report ACK information to the base station through PUCCH resources (for a specific TB).

[0192] - Second case: If the TX UE receives ACK information from the RX UE, the TX UE may report the ACK information to the base station through the PUCCH resources (for a specific TB).

[0193] For example, the applied options may be configured differently based on the first case and / or the second case. Specifically, for example, in the case of the first case, the TX UE may operate based on option 2 and / or option 3. For example, in the case of the second case, the TX UE may operate based on option 1 and / or option 2.

[0194] For example, whether the TX UE should send MAC PDU or dummy information through the resources allocated by the RE-TX DG DCI can be configured or pre-configured for the TX UE by the base station / network. For example, whether the TX UE operating based on the above option should send MAC PDU or dummy information through the resources allocated by the RE-TX DG DCI can be configured or pre-configured for the TX UE by the base station / network. For example, the base station / network can send information related to whether the TX UE should send MAC PDU or dummy information through the resources allocated by the RE-TX DG DCI to the TX UE. For example, if there is no new packet (e.g., MAC PDU) to be sent in the buffer of the TX UE, the above rules can be applied (restrictively). For example, if there is no remaining data in the buffer of the TX UE, the above rules can be applied (restrictively). For example, if there is no (new) MAC PDU to be generated / sent by the TX UE, the above rules can be applied (restrictively). For example, if the TX UE flushes the (previous) buffer / data related to the HARQ process indicated by the RE-TX DG DCI, the above rules may be applied (with restriction). For example, if the TX UE performs SL transmission based on the DG sent by the base station, the above rules may be applied (with restriction). For example, if the TX UE performs SL transmission based on the CG sent by the base station, the above rules may be applied (with restriction).

[0195] Fig.13 A case is shown in which a base station according to an embodiment of the present disclosure does not send DCI related to transmission (retransmission) to a UE because the base station mistakenly recognizes NACK information sent by a TX UE as ACK information. Fig.13 The embodiments of the present disclosure may be combined with various embodiments of the present disclosure.

[0196] Reference Fig.13 In step S1310, the TX UE may send a PSCCH and / or a PSSCH to the RX UE. For example, the TX UE may send a PSCCH and / or a PSSCH to the RX UE using the SL resources allocated by the base station. For example, the SL resources may be allocated to the TX UE via a dynamic grant (DG) sent by the base station. For example, the SL resources may be allocated to the TX UE via a configuration grant (CG) sent by the base station.

[0197] In step S1320, the TX UE may receive NACK information from the RX UE via the PSFCH. For example, if the RX UE fails to receive / decode the PSCCH and / or the PSSCH, the RX UE may send NACK information to the TX UE via the PSFCH. Alternatively, for example, if the RX UE fails to receive / decode the PSCCH and / or the PSSCH, the TX UE may not receive the HARQ feedback information from the RX UE via the PSFCH. Alternatively, for example, even if the RX UE has successfully received / decoded the PSCCH and / or the PSSCH, for example, due to a poor channel environment, the TX UE may not receive the HARQ feedback information from the RX UE via the PSFCH.

[0198] In step S1330 , the TX UE may send NACK information to the base station through the PUCCH.

[0199] In step S1340, the base station may determine that the NACK information sent by the TX UE is ACK information. That is, even if the TX UE has sent NACK information to the base station, the base station may mistakenly identify the NACK information as ACK information. In this case, the base station may not allocate additional transmission (retransmission) resources to the TX UE. For example, the base station may not send RE-TX DG DCI to the TX UE.

[0200] In step S1350, the base station may allocate transmission resources to the TX UE. For example, the base station may send a DG related to the transmission resources to the TX UE via DCI so as to allocate transmission resources to the TX UE. For example, the base station may send a DCI including a DG related to the transmission resources to the TX UE so as to allocate transmission resources to the TX UE. For example, the DG related to the transmission resources may indicate the transmission resources. For convenience of description, the DCI including the DG related to the transmission resources may be referred to as DG DCI. For example, the DG DCI may include a switching NDI and a HARQ process ID related to the NACK information sent via the PUCCH.

[0201] In addition, Fig.13 In the implementation manner, it is assumed that the TX UE sends PSCCH and / or PSSCH based on the DG sent by the base station. Alternatively, it is assumed that the TX UE sends PSCCH and / or PSSCH based on the DG and / or CG sent by the base station.

[0202] As described above, even if the TX UE has sent NACK information to the base station, if the TX UE receives DG DCI from the base station, the TX UE may operate based on at least one of the following options. That is, even if the TX UE has sent NACK information to the base station, if the TX UE receives DG DCI instead of RE-TX DG DCI from the base station, the TX UE may operate based on at least one of the following options.

[0203] 4) Option 4

[0204] For example, the TX UE may send a (new) packet on resources allocated by the DG DCI, and the TX UE may send (SL) HARQ information determined based on conventional rules to the base station via PUCCH resources associated with the DG DCI. For example, the TX UE may send a new packet on resources allocated by the DG DCI, and the TX UE may send HARQ feedback information received from the RX UE to the base station via PUCCH resources associated with the DG DCI.

[0205] For example, option 4 may be restrictively applied only when there is a new packet (e.g., MAC PDU) to be sent in the buffer of the TX UE. For example, option 4 may be restrictively applied only when there is remaining data in the buffer of the TX UE. For example, option 4 may be restrictively applied only when there is a (new) MAC PDU to be generated / sent by the TX UE.

[0206] 5) Option 5

[0207] For example, the TX UE may not send PSCCH and / or PSSCH on the resources allocated by the DG DCI, and the TX UE may send ACK information or NACK information to the base station through the PUCCH resources related to the DG DCI. For example, the TX UE may not send MAC PDU or dummy information on the resources allocated by the DG DCI, and the TX UE may send ACK information or NACK information to the base station through the PUCCH resources related to the DG DCI. For example, the dummy information may be predefined information. For example, the MAC PDU may be a MAC PDU that the TX UE previously sent to the RX UE. For example, the MAC PDU may be a MAC PDU related to the HARQ process ID related to the NACK information sent by the TX UE to the base station through the PUCCH in step S1330.

[0208] 6) Option 6

[0209] For example, the TX UE may ignore the DG DCI, and the TX UE may not send a MAC PDU or dummy information on the resources allocated by the DG DCI, and the TX UE may not send ACK information or NACK information to the base station through the PUCCH resources related to the DG DCI. For example, the TX UE may omit / skip the transmission of the MAC PDU or dummy information on the resources allocated by the DG DCI, and the TX UE may omit / skip the transmission on the PUCCH resources related to the DG DCI. For example, the dummy information may be predefined information. For example, the MAC PDU may be a MAC PDU that the TX UE previously sent to the RX UE. For example, the MAC PDU may be a MAC PDU related to the HARQ process ID related to the NACK information sent by the TX UE to the base station through the PUCCH in step S1330.

[0210] For example, in option 5 and / or option 6, the TX UE may ignore / discard the grant related to the DG DCI. For example, in option 5 and / or option 6, there may be no new packet (e.g., MAC PDU) to be sent in the buffer of the TX UE. For example, in option 5 and / or option 6, there may be no remaining data in the buffer of the TX UE. For example, in option 5 and / or option 6, there may be no (new) MAC PDU to be generated / sent by the TX UE. For example, in option 5 and / or option 6, the TX UE may have flushed the (previous) buffer / data related to the HARQ process indicated by the DG DCI.

[0211] For example, if the resources allocated by the DG DCI are insufficient for the TX UE to send the (previous) buffer / data related to the HARQ process, Option 5 may be (restrictively) applied. For example, if the (effective) coding rate value exceeds a preconfigured threshold (e.g., 1), Option 5 may be (restrictively) applied. For example, if the TB size of the (previous) buffer / data related to the HARQ process cannot be maintained, Option 5 may be (restrictively) applied.

[0212] For example, if the resources allocated by the DG DCI are insufficient for the TX UE to send the (previous) buffer / data related to the HARQ process, Option 6 may be (restrictively) applied. For example, if the (effective) coding rate value exceeds a preconfigured threshold (e.g., 1), Option 6 may be (restrictively) applied. For example, if the TB size of the (previous) buffer / data related to the HARQ process cannot be maintained, Option 6 may be (restrictively) applied.

[0213] 7) Option 7

[0214] For example, the TX UE may send PSCCH and / or PSSCH on resources allocated by DG DCI, and the TX UE may (always) send ACK information or NACK information to the base station via PUCCH resources related to the DG DCI. For example, the TX UE may send MAC PDU or dummy information on resources allocated by DG DCI, and the TX UE may send ACK information or NACK information to the base station via PUCCH resources related to the DG DCI. For example, the dummy information may be predefined information. For example, the MAC PDU may be a MAC PDU previously sent by the TX UE to the RX UE. For example, the MAC PDU may be a MAC PDU related to a HARQ process ID related to the NACK information sent by the TX UE to the base station via PUCCH in step S1330.

[0215] For example, the TX UE may send PSCCH and / or PSSCH on resources allocated by the DG DCI, and the TX UE may send HARQ feedback information received from the RX UE in response to the PSCCH and / or PSSCH to the base station through PUCCH resources related to the DG DCI. For example, the TX UE may send MAC PDU or dummy information on resources allocated by the DG DCI, and the TX UE may send HARQ feedback information received from the RX UE in response to the PSCCH and / or PSSCH to the base station through PUCCH resources related to the DG DCI. For example, the dummy information may be predefined information. For example, the MAC PDU may be a MAC PDU previously sent by the TX UE to the RX UE. For example, the MAC PDU may be a MAC PDU related to the HARQ process ID related to the NACK information sent by the TX UE to the base station through the PUCCH in step S1330.

[0216] Hereinafter, if the TX UE operates based on Option 7, the operation of the TX UE will be described in detail. For example, if the TX UE sends PSCCH and / or PSSCH to the RX UE on resources allocated by DG DCI, the TX UE may set the HARQ feedback request field included in the SCI related to the PSCCH and / or PSSCH to "DISABLED". For example, if the TX UE sends PSCCH and / or PSSCH to the RX UE on resources allocated by DG DCI, the TX UE may set the HARQ feedback request field included in the SCI related to the PSCCH and / or PSSCH to "ENABLED". For example, if the TX UE sends PSCCH and / or PSSCH to the RX UE on resources allocated by DG DCI, the TX UE may maintain / set the NDI field value included in the SCI related to the PSCCH and / or PSSCH to be the same as the (previous) NDI field value related to the HARQ process ID related to the NACK information sent through the PUCCH. For example, if the TX UE sends PSCCH and / or PSSCH to the RX UE on resources allocated by DG DCI, the TX UE may set the SL HARQ process ID field value included in the SCI related to the PSCCH and / or PSSCH to the HARQ process ID related to the NACK information sent through the PUCCH. For example, if the TX UE sends PSCCH and / or PSSCH to the RX UE on resources allocated by DG DCI, the TX UE may set the source ID field value and / or destination ID field value included in the SCI related to the PSCCH and / or PSSCH to the source ID field value and / or destination ID field value related to the NACK information sent through the PUCCH. For example, the source ID may be an L1 source ID, and the destination ID may be an L1 destination ID. For example, if the TX UE sends PSCCH and / or PSSCH to the RX UE on resources allocated by the DG DCI, the TX UE may inform the RX UE through a preconfigured field included in the SCI related to the PSCCH and / or PSSCH that the base station mistakenly identifies the NACK through the PUCCH as ACK (i.e., a NACK-TO-AC error occurs). In the above case, if the RX UE receives a message and / or packet (e.g., a MAC PDU or dummy information) from the TX UE, the RX UE may discard the message and / or packet. For example, the RX UE does not attempt to decode the PSSCH, and the RX UE may discard the message and / or packet. For example, the RX UE may not store the message and / or packet in a buffer, and the RX UE may discard the message and / or packet.

[0217] For example, Option 5 may be restrictively applied only when there is no new packet (e.g., MAC PDU) to be sent in the buffer of the TX UE. For example, Option 5 may be restrictively applied only when there is no remaining data in the buffer of the TX UE. For example, Option 5 may be restrictively applied only when there is no (new) MAC PDU to be generated / sent by the TX UE. For example, Option 5 may be restrictively applied only when the TX UE flushes the (previous) buffer / data related to the HARQ process indicated by the DG DCI.

[0218] For example, Option 6 may be restrictively applied only when there is no new packet (e.g., MAC PDU) to be sent in the buffer of the TX UE. For example, Option 6 may be restrictively applied only when there is no remaining data in the buffer of the TX UE. For example, Option 6 may be restrictively applied only when there is no (new) MAC PDU to be generated / sent by the TX UE. For example, Option 6 may be restrictively applied only when the TX UE flushes the (previous) buffer / data related to the HARQ process indicated by the DG DCI.

[0219] For example, Option 7 may be restrictively applied only when there is no new packet (e.g., MAC PDU) to be sent in the buffer of the TX UE. For example, Option 7 may be restrictively applied only when there is no remaining data in the buffer of the TX UE. For example, Option 7 may be restrictively applied only when there is no (new) MAC PDU to be generated / sent by the TX UE. For example, Option 7 may be restrictively applied only when the TX UE flushes the (previous) buffer / data related to the HARQ process indicated by the DG DCI.

[0220] For example, if option 4 is applied, even if the TX UE sends NACK information to the base station through the PUCCH, if the NDI field value included in the (received) DG DCI indicating the same HARQ process switches, the TX UE can refresh the buffer (of the relevant HARQ process).

[0221] For example, if option 5 is applied, even if the TX UE sends NACK information to the base station through the PUCCH, if the NDI field value included in the (received) DG DCI indicating the same HARQ process switches, the TX UE can refresh the buffer (of the relevant HARQ process).

[0222] For example, if option 6 is applied, even if the TX UE sends NACK information to the base station through the PUCCH, if the NDI field value included in the (received) DG DCI indicating the same HARQ process switches, the TX UE can refresh the buffer (of the relevant HARQ process).

[0223] For example, if option 7 is applied, even if the TX UE sends NACK information to the base station through the PUCCH, if the NDI field value included in the (received) DG DCI indicating the same HARQ process switches, the TX UE can refresh the buffer (of the relevant HARQ process).

[0224] For example, whether the TX UE should send MAC PDU or dummy information through the resources allocated by the DG DCI can be configured or pre-configured by the base station / network for the TX UE. For example, whether the TX UE operating based on the above option should send MAC PDU or dummy information through the resources allocated by the DG DCI can be configured or pre-configured by the base station / network for the TX UE. For example, the base station / network can send information related to whether the TX UE should send MAC PDU or dummy information through the resources allocated by the DG DCI to the TX UE. For example, if there is no new packet (e.g., MAC PDU) to be sent in the buffer of the TX UE, the above rules can be applied (restrictively). For example, if there is no remaining data in the buffer of the TX UE, the above rules can be applied (restrictively). For example, if there is no (new) MAC PDU to be generated / sent by the TX UE, the above rules can be applied (restrictively). For example, if the TX UE refreshes the (previous) buffer / data related to the HARQ process indicated by the DG DCI, the above rules can be applied (restrictively). For example, if the TX UE performs SL transmission based on the DG sent by the base station, the above rules may be applied (with restriction). For example, if the TX UE performs SL transmission based on the CG sent by the base station, the above rules may be applied (with restriction).

[0225] Based on the embodiments of the present disclosure, the options applied to the TX UE and / or the RX UE may be configured differently based on whether the TX UE receives ACK information from the RX UE. For example, the options applied to the TX UE and / or the RX UE may be configured differently based on whether the TX UE sends a HARQ ENABLED MAC PDU to the RX UE. For example, the HARQ ENABLED MAC PDU may be a MAC PDU that requires HARQ feedback. For example, the options applied to the TX UE and / or the RX UE may be configured differently based on whether the HARQ feedback request field included in the SCI sent by the TX UE indicates that the HARQ feedback is enabled. For example, the options applied to the TX UE and / or the RX UE may be configured differently based on the broadcast type. For example, the broadcast type may include at least one of broadcast, multicast and / or unicast. For example, the options applied to the TX UE and / or the RX UE may be configured differently based on whether the TX UE refreshes the buffer (of the relevant HARQ process) after receiving ACK information from the RX UE via the PSFCH. For example, the options applied to the TX UE and / or RX UE may be configured differently based on whether the TX UE refreshes the buffer (of the relevant HARQ process) after sending ACK information to the base station via the PUCCH. For example, the options applied to the TX UE and / or RX UE may be configured differently based on whether the TX UE refreshes the buffer related to the HARQ process indicated by the DG DCI. For example, the options applied to the TX UE and / or RX UE may be configured differently based on whether the TX UE refreshes the buffer related to the HARQ process indicated by the RE-TX DG DCI. For example, the options applied to the TX UE and / or RX UE may be configured differently based on the MODE 1 type (e.g., DG or CG). For example, the options applied to the TX UE and / or RX UE may be configured differently based on the type of service. For example, the options applied to the TX UE and / or RX UE may be configured differently based on the priority of the service. For example, the options applied to the TX UE and / or RX UE may be configured differently based on the congestion level (e.g., CBR) (of the resource pool).

[0226] For example, in Fig.12 In an embodiment of the present invention, if the TX UE receives ACK information (for the transmitted MAC PDU) from the RX UE via the PSFCH, the TX UE may be configured to flush its buffer (of the relevant HARQ process), and the TX UE may be configured to ignore additional SL grants received later indicating the same HARQ process ID and unswitched NDI. Fig.12In an embodiment of , if the TX UE sends a HARQ ENABLED MAC PDU, the TX UE may be configured to flush its buffer (of the relevant HARQ process), and the TX UE may be configured to ignore additional SL grants received later indicating the same HARQ process ID and unswitched NDI. Fig.12 In an embodiment, if the TX UE sets the HARQ feedback request field included in the SCI to "ENABLED" when sending a MAC PDU, the TX UE may be configured to flush its buffer (of the relevant HARQ process), and the TX UE may be configured to ignore additional SL grants received later indicating the same HARQ process ID and unswitched NDI. In the above case, the TX UE flushes its buffer (of the relevant HARQ process), and the TX UE may ignore additional SL grants received later indicating the same HARQ process ID and unswitched NDI. In the above case, Option 2 and / or Option 1 may be applied.

[0227] For example, in Fig.12 In an embodiment of the present invention, if the TX UE sends a HARQ DISABLED MAC PDU to the RX UE, the TX UE may operate based on Option 3. For example, in Fig.12 In an embodiment of the present invention, if the TX UE sets the HARQ feedback request field included in the SCI to "DISABLED" when sending the MAC PDU, the TX UE may operate based on option 3. For example, in Fig.12 In an embodiment of the present invention, if the TX UE does not flush the buffer (of the relevant HARQ process) after sending ACK information to the base station via the PUCCH, the TX UE may operate based on option 3. For example, in Fig.12 In an embodiment, if the TX UE sends a MAC PDU related to broadcasting, the TX UE can operate based on option 3.

[0228] For example, in Fig.12 In an embodiment of the present invention, if the TX UE is configured to flush the buffer (of the relevant HARQ process) after sending ACK information to the base station via the PUCCH, the TX UE may operate based on Option 2 and / or Option 1. Fig.12 In an embodiment of the present invention, if the TX UE sends a HARQ DISABLED MAC PDU to the RX UE, and if the TX UE is configured to flush the buffer (of the relevant HARQ process) after sending ACK information to the base station via the PUCCH, the TX UE may operate based on Option 2 and / or Option 1. Fig.12In an embodiment of the present invention, if the TX UE sets the HARQ feedback request field included in the SCI to "DISABLED" when sending the MAC PDU, and if the TX UE is configured to flush the buffer (of the relevant HARQ process) after sending ACK information to the base station through the PUCCH, the TX UE may operate based on Option 2 and / or Option 1. For example, in Fig.12 In an embodiment, if the TX UE sends a MAC PDU related to broadcasting, and if the TX UE is configured to flush the buffer (of the relevant HARQ process) after sending ACK information to the base station via the PUCCH, the TX UE may operate based on Option 2 and / or Option 1.

[0229] For example, in Fig.12 In an embodiment of the present invention, if the TX UE (has) flushed the buffer associated with the HARQ process ID indicated by the RE-TX DG DCI, the TX UE may operate based on Option 2 and / or Option 1. Fig.12 In an embodiment, if the TX UE has not (yet) flushed the buffer associated with the HARQ process ID indicated by the RE-TX DG DCI, the TX UE may operate based on Option 3 and / or Option 1. For example, if the number of transmissions (retransmissions) associated with a specific TB reaches the (preconfigured) maximum allowed number of retransmissions, the TX UE may not flush the buffer associated with the HARQ process ID indicated by the RE-TX DG DCI. For example, if the number of transmissions (retransmissions) associated with a specific TB reaches the (preconfigured) maximum allowed number of retransmissions, the TX UE may flush the buffer associated with the HARQ process ID indicated by the RE-TX DG DCI.

[0230] For example, in Fig.13 In an embodiment of the present invention, if the priority of the service sent by the TX UE is higher than a preconfigured threshold, the TX UE may be configured to operate based on one of option 4, option 5 and / or option 7. Fig.13 In an embodiment of the present invention, if the congestion level (of the resource pool) is lower than a preconfigured threshold, the TX UE may be configured to operate based on one of option 4, option 5 and / or option 7. Otherwise, the TX UE may be configured to operate based on option 6.

[0231] For example, in Fig.13 In an embodiment of the present invention, if the priority of the service sent by the TX UE is lower than a preconfigured threshold, the TX UE may be configured to operate based on option 6. For example, in Fig.13 In an embodiment, if the congestion level (of the resource pool) is higher than a preconfigured threshold, the TX UE may be configured to operate based on option 6.

[0232] Based on the embodiments of the present disclosure, if the UE sends ACK information to the base station through the preconfigured PUCCH, the UE may be configured to refresh the buffer (of the relevant HARQ process). For example, even if the UE sends NACK information to the base station through the PUCCH, if the NDI field value included in the (received) DG DCI indicating the same HARQ process switches, the UE may be configured to refresh the buffer (of the relevant HARQ process). For example, even if the UE sends ACK information to the base station through the PUCCH, if the NDI field value included in the (received) DG DCI indicating the same HARQ process does not switch, the UE may be configured to refresh the buffer (of the relevant HARQ process). For example, if the TX UE receives ACK information from the RX UE through the PSFCH, the TX UE may be configured to refresh the buffer (of the relevant HARQ process). For example, if the number of transmissions (retransmissions) (related to a specific TB) reaches the preconfigured maximum allowed number of transmissions (retransmissions), the UE may be configured to refresh the buffer (of the relevant HARQ process). For example, the UE may be a TX UE. In the above case, the UE can refresh the buffer (of the relevant HARQ process). Herein, for example, if the UE performs SL communication based on the DG sent by the base station, the above rules can be applied (restrictively). For example, if the UE performs SL communication based on the CG sent by the base station, the above rules can be applied (restrictively).

[0233] Based on the embodiments of the present disclosure, the options applied to the UE may be configured or preconfigured for the UE from the base station / network. For example, the base station / network may send information related to the options applied to the UE to the UE. For example, the options applied to the UE may include at least one of the options applied to the UE for each MODE 1 operation type (e.g., DG or CG), the options applied to the UE for each CG-related RE-TX DG, and / or the options applied to the UE for each DG-related RE-TX DG.

[0234] Fig.14 The operation of the UE when the UE that has refreshed the buffer related to the HARQ process receives information about the retransmission resources related to the HARQ process according to an embodiment of the present disclosure is shown. Fig.14 The embodiments of the present disclosure may be combined with various embodiments of the present disclosure.

[0235] Reference Fig.14In step S1410, the TX UE may receive information related to CG resources and information related to the maximum number of transmissions from the base station. For example, the TX UE may receive information related to CG resources and information related to the maximum number of transmissions from the base station through RRC signaling. For example, the TX UE may receive information related to the maximum number of transmissions from the base station through RRC signaling, and the TX UE may receive information related to CG resources from the base station through PDCCH (e.g., DCI). For example, the CG resources may be resources periodically allocated to the TX UE for SL transmission.

[0236] In step S1420, the TX UE may send the same MAC PDU maximum number of transmissions to the RX UE based on HARQ retransmission. Herein, HARQ retransmission may refer to a retransmission scheme in which the TX UE performs retransmission based on SL HARQ feedback from the RX UE. Alternatively, for example, the TX UE may send the same MAC PDU maximum number of transmissions to the RX UE based on blind retransmission. Herein, blind retransmission may refer to a retransmission scheme in which the TX UE performs retransmission without SL HARQ feedback from the RX UE.

[0237] In step S1430, the TX UE may refresh the HARQ buffer associated with the SL process. For example, if the number of transmissions of the MAC PDU reaches the maximum number of retransmissions, the TX UE may refresh the HARQ buffer associated with the SL process. For example, if the number of transmissions of the MAC PDU sent based on the first SL process ID reaches the maximum number of retransmissions, the TX UE may refresh the HARQ buffer associated with the SL process (i.e., the SL process associated with the first SL process ID). In the present disclosure, the SL process may be referred to as the SL HARQ process.

[0238] In step S1440, the TX UE may receive information related to the DG resources from the base station. For example, the DG resources may include resources for SL retransmission (ie, retransmission of the MAC PDU) and PUCCH resources. For example, the TX UE may receive information related to the DG resources from the base station via DCI.

[0239] In the above case, if the buffer related to the SL process is refreshed, the TX UE may not retransmit the MAC PDU to the RXUE based on the DG resource, and the TX UE may not send the SL HARQ feedback information related to the MAC PDU to the base station based on the PUCCH resource. That is, if the SL HARQ process ID corresponding to the SL grant received by the TX UE through the PDCCH is related to the SL process of the empty HARQ buffer, the TX UE may ignore the SL grant (e.g., DG resource). Therefore, the TX UE may not retransmit the MAC PDU to the RXUE based on the SL grant, and the TX UE may not send the SL HARQ feedback information related to the MAC PDU to the base station based on the PUCCH resource.

[0240] Fig.15 A method for a first device to perform wireless communication based on an embodiment of the present disclosure is shown. Fig.15 The embodiments of the present disclosure may be combined with various embodiments of the present disclosure.

[0241] Reference Fig.15 In step S1510, the first device may receive information related to a first side link (SL) grant, information related to a first physical uplink control channel (PUCCH) resource, and information related to a maximum number of transmissions of a medium access control (MAC) protocol data unit (PDU) from a base station. In step S1520, the first device may send a MAC PDU to a second device based on a first SL grant and a SL hybrid automatic repeat request (HARQ) process ID. In step S1530, based on the number of transmissions of the MAC PDU to the second device reaching the maximum number of transmissions, the first device may refresh a buffer related to the SL HARQ process ID. In step S1540, the first device may receive downlink control information (DCI) related to the SL HARQ process ID from the base station via a physical downlink control channel (PDCCH). For example, the DCI may include information related to a second SL grant for retransmission of the MAC PDU and information related to a second PUCCH resource. For example, based on the buffer related to the SL HARQ process ID being flushed, the first device may not send the MAC PDU to the second device based on the second SL grant, and the first device may not send the SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

[0242] For example, the SL HARQ process ID may be associated with the MAC PDU, and the SL HARQ process ID may be sent to the second device based on sidelink control information (SCI) sent through a physical sidelink shared channel (PSSCH). For example, based on a buffer associated with the SL HARQ process ID being flushed, the first device may ignore the second SL grant. For example, the first SL grant may be a SL configuration grant (CG), and the SL CG may be one of a first type SL CG or a second type SL CG.

[0243] In addition, for example, the first device may send NACK information related to the MAC PDU to the base station based on the first PUCCH resource related to the first SL grant. For example, DCI may be received from the base station based on the NACK information. For example, if the first device receives NACK information from the second device via PSFCH, the first device may send NACK information related to the MAC PDU to the base station based on the first PUCCH resource related to the first SL grant. For example, if the first device fails to receive HARQ feedback from the second device via PSFCH, the first device may send NACK information related to the MAC PDU to the base station based on the first PUCCH resource related to the first SL grant. Specifically, for example, if the second device fails to decode the PSCCH sent by the first device, the second device may not send HARQ feedback to the first device, and the first device may fail to receive HARQ feedback from the second device via PSFCH. For example, even if the second device has sent HARQ feedback to the first device, the first device may fail to receive HARQ feedback from the second device via PSFCH. For example, if the channel state is not good, the first device may fail to receive HARQ feedback from the second device through the PSFCH even if the second device has sent HARQ feedback to the first device. For example, if the first device fails to perform PSFCH reception or PSFCH monitoring operations related to the MAC PDU sent by the first device due to a prioritization operation, the first device may fail to receive HARQ feedback from the second device through the PSFCH. For example, the prioritization operation may include a prioritization operation between SL communication and UL communication, a prioritization operation between LTE SL communication and NR SL communication, a prioritization operation between PSFCH transmissions, a priority operation between PSFCH transmissions and PSFCH receptions, and the like.

[0244] In addition, for example, based on the number of transmissions of the MAC PDU to the second device reaching the maximum number of transmissions, the first device may send ACK information related to the MAC PDU to the base station.

[0245] For example, based on the first device receiving ACK information related to the MAC PDU from the second device through a physical sidelink feedback channel (PSFCH), the buffer related to the SL HARQ process ID can be refreshed.

[0246] For example, based on the first device sending ACK information related to the MAC PDU to the base station, the buffer related to the SL HARQ process ID can be refreshed.

[0247] For example, based on the first device setting the field related to HARQ feedback in the SCI related to the MAC PDU that has reached the maximum number of transmissions to enabled, the buffer related to the SL HARQ process ID may be flushed.

[0248] For example, based on (i) the first device sending NACK information related to the MAC PDU to the base station and (ii) the DCI related to the SL HARQ process ID includes a toggle new data indicator (NDI), the buffer related to the SL HARQ process ID can be refreshed.

[0249] For example, based on (i) the first device sending ACK information related to the MAC PDU to the base station and (ii) the DCI related to the SL HARQ process ID includes a non-switched new data indicator (NDI), the buffer related to the SL HARQ process ID can be refreshed.

[0250] For example, the maximum number of transmissions may be determined based on at least one priority of at least one logical channel associated with the MAC PDU. For example, the maximum number of transmissions may be associated with the highest priority among at least one priority of at least one logical channel.

[0251] The proposed method can be applied to devices based on various embodiments of the present disclosure. First, the processor 102 of the first device 100 can control the transceiver 106 to receive information related to the first side link (SL) grant, information related to the first physical uplink control channel (PUCCH) resource, and information related to the maximum number of transmissions of the medium access control (MAC) protocol data unit (PDU) from the base station. In addition, the processor 102 of the first device 100 can control the transceiver 106 to send a MAC PDU to the second device based on the first SL grant and the SL hybrid automatic repeat request (HARQ) process ID. In addition, based on the number of transmissions of the MAC PDU to the second device reaching the maximum number of transmissions, the processor 102 of the first device 100 can refresh the buffer related to the SL HARQ process ID. In addition, the processor 102 of the first device 100 can control the transceiver 106 to receive downlink control information (DCI) related to the SL HARQ process ID from the base station through the physical downlink control channel (PDCCH). For example, the DCI may include information related to a second SL grant for retransmission of the MAC PDU and information related to a second PUCCH resource. For example, based on the buffer related to the SL HARQ process ID being refreshed, the first device may not send the MAC PDU to the second device based on the second SL grant, and the first device may not send SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

[0252] Based on the embodiments of the present disclosure, a first device configured to perform wireless communication may be provided. For example, the first device may include: one or more memories storing instructions; one or more transceivers; and one or more processors connected to the one or more memories and the one or more transceivers. For example, one or more processors may execute instructions to: receive information related to a first side link (SL) grant, information related to a first physical uplink control channel (PUCCH) resource, and information related to the maximum number of transmissions of a medium access control (MAC) protocol data unit (PDU) from a base station; send a MAC PDU to a second device based on a first SL grant and a SL hybrid automatic repeat request (HARQ) process ID; based on the number of transmissions of the MAC PDU to the second device reaching the maximum number of transmissions, refresh the buffer related to the SL HARQ process ID; and receive downlink control information (DCI) related to the SL HARQ process ID from the base station via a physical downlink control channel (PDCCH). For example, the DCI may include information related to a second SL grant for retransmission of the MAC PDU and information related to a second PUCCH resource. For example, based on the buffer related to the SL HARQ process ID being flushed, the first device may not send the MAC PDU to the second device based on the second SL grant, and the first device may not send the SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

[0253] Based on the embodiments of the present disclosure, a device configured to control a first user equipment (UE) may be provided. For example, the device may include: one or more processors; and one or more memories, which are operatively connected to the one or more processors and store instructions. For example, one or more processors may execute instructions to: receive information related to a first side link (SL) grant, information related to a first physical uplink control channel (PUCCH) resource, and information related to the maximum number of transmissions of a medium access control (MAC) protocol data unit (PDU) from a base station; send a MAC PDU to a second UE based on a first SL grant and a SL hybrid automatic repeat request (HARQ) process ID; based on the number of transmissions of the MAC PDU to the second UE reaching the maximum number of transmissions, refresh the buffer related to the SL HARQ process ID; and receive downlink control information (DCI) related to the SL HARQ process ID from the base station via a physical downlink control channel (PDCCH). For example, the DCI may include information related to a second SL grant for retransmission of the MAC PDU and information related to a second PUCCH resource. For example, based on the buffer related to the SL HARQ process ID being flushed, the first UE may not send the MAC PDU to the second UE based on the second SL grant, and the first UE may not send the SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

[0254] Based on the embodiments of the present disclosure, a non-transitory computer-readable storage medium storing instructions may be provided. For example, when the non-transitory computer-readable storage medium storing instructions is executed, it may enable the first device to: receive information related to the first side link (SL) grant, information related to the first physical uplink control channel (PUCCH) resource, and information related to the maximum number of transmissions of the medium access control (MAC) protocol data unit (PDU) from the base station; send a MAC PDU to the second device based on the first SL grant and the SL hybrid automatic repeat request (HARQ) process ID; based on the number of transmissions of the MAC PDU to the second device reaching the maximum number of transmissions, refresh the buffer related to the SL HARQ process ID; and receive downlink control information (DCI) related to the SL HARQ process ID from the base station via the physical downlink control channel (PDCCH). For example, the DCI may include information related to the second SL grant for the retransmission of the MAC PDU and information related to the second PUCCH resource. For example, based on the buffer related to the SL HARQ process ID being flushed, the first device may not send the MAC PDU to the second device based on the second SL grant, and the first device may not send the SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

[0255] Fig.16 A method for a base station to perform wireless communication based on an embodiment of the present disclosure is shown. Fig.16 The embodiments of the present disclosure may be combined with various embodiments of the present disclosure.

[0256] Reference Fig.16 In step S1610, the base station may send information related to a first side link (SL) grant, information related to a first physical uplink control channel (PUCCH) resource, and information related to a maximum number of transmissions of a medium access control (MAC) protocol data unit (PDU) to the first device. In step S1620, the base station may send downlink control information (DCI) related to a SL hybrid automatic repeat request (HARQ) process ID to the first device via a physical downlink control channel (PDCCH). For example, the DCI may include information related to a second SL grant for retransmission of the MAC PDU and information related to a second PUCCH resource. For example, based on the first SL grant and the SL HARQ process ID, the MAC PDU may be sent by the first device to the second device. For example, based on the number of transmissions of the MAC PDU to the second device reaching the maximum number of transmissions, the buffer related to the SL HARQ process ID may be refreshed by the first device. For example, based on the buffer related to the SL HARQ process ID being flushed, the first device may not send the MAC PDU to the second device based on the second SL grant, and the first device may not send the SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

[0257] The proposed method can be applied to devices based on various embodiments of the present disclosure. First, the processor 202 of the base station 200 can control the transceiver 206 to send information related to the first side link (SL) grant, information related to the first physical uplink control channel (PUCCH) resource, and information related to the maximum number of transmissions of the medium access control (MAC) protocol data unit (PDU) to the first device. In addition, the processor 202 of the base station 200 can control the transceiver 206 to send downlink control information (DCI) related to the SL hybrid automatic repeat request (HARQ) process ID to the first device through the physical downlink control channel (PDCCH). For example, the DCI may include information related to the second SL grant for retransmission of the MAC PDU and information related to the second PUCCH resource. For example, based on the first SL grant and the SL HARQ process ID, the MAC PDU can be sent by the first device to the second device. For example, based on the number of transmissions of the MAC PDU to the second device reaching the maximum number of transmissions, the buffer related to the SL HARQ process ID can be refreshed by the first device. For example, based on the buffer related to the SL HARQ process ID being flushed, the first device may not send the MAC PDU to the second device based on the second SL grant, and the first device may not send the SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

[0258] Based on the embodiments of the present disclosure, a base station configured to perform wireless communication may be provided. For example, the base station may include: one or more memories storing instructions; one or more transceivers; and one or more processors connected to the one or more memories and the one or more transceivers. For example, one or more processors may execute instructions to: send information related to a first side link (SL) grant, information related to a first physical uplink control channel (PUCCH) resource, and information related to the maximum number of transmissions of a medium access control (MAC) protocol data unit (PDU) to a first device; and send downlink control information (DCI) related to a SL hybrid automatic repeat request (HARQ) process ID to the first device through a physical downlink control channel (PDCCH). For example, the DCI may include information related to a second SL grant for retransmission of a MAC PDU and information related to a second PUCCH resource. For example, based on the first SL grant and the SL HARQ process ID, a MAC PDU may be sent by the first device to the second device. For example, based on the number of transmissions of the MAC PDU to the second device reaching the maximum number of transmissions, the buffer related to the SL HARQ process ID may be refreshed by the first device. For example, based on the buffer related to the SL HARQ process ID being flushed, the first device may not send the MAC PDU to the second device based on the second SL grant, and the first device may not send the SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

[0259] Based on the embodiments of the present disclosure, a device configured to control a base station may be provided. For example, the device may include: one or more processors; and one or more memories, which are operatively connected to the one or more processors and store instructions. For example, one or more processors may execute instructions to: send information related to a first side link (SL) grant, information related to a first physical uplink control channel (PUCCH) resource, and information related to the maximum number of transmissions of a medium access control (MAC) protocol data unit (PDU) to a first UE; and send downlink control information (DCI) related to a SL hybrid automatic repeat request (HARQ) process ID to the first UE via a physical downlink control channel (PDCCH). For example, the DCI may include information related to a second SL grant for retransmission of a MAC PDU and information related to a second PUCCH resource. For example, based on the first SL grant and the SL HARQ process ID, a MAC PDU may be sent by the first UE to the second UE. For example, based on the number of transmissions of the MAC PDU to the second UE reaching the maximum number of transmissions, the buffer related to the SL HARQ process ID may be refreshed by the first UE. For example, based on the buffer related to the SL HARQ process ID being flushed, the first UE may not send the MAC PDU to the second UE based on the second SL grant, and the first UE may not send the SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

[0260] Based on the embodiments of the present disclosure, a non-transitory computer-readable storage medium storing instructions may be provided. For example, the non-transitory computer-readable storage medium stores instructions, which, when executed, may cause the base station to: send information related to a first side link (SL) grant, information related to a first physical uplink control channel (PUCCH) resource, and information related to the maximum number of transmissions of a medium access control (MAC) protocol data unit (PDU) to a first device; and send downlink control information (DCI) related to a SL hybrid automatic repeat request (HARQ) process ID to the first device via a physical downlink control channel (PDCCH). For example, the DCI may include information related to a second SL grant for retransmission of a MAC PDU and information related to a second PUCCH resource. For example, based on the first SL grant and the SL HARQ process ID, a MAC PDU may be sent by the first device to the second device. For example, based on the number of transmissions of the MAC PDU to the second device reaching the maximum number of transmissions, the buffer related to the SL HARQ process ID may be refreshed by the first device. For example, based on the buffer related to the SL HARQ process ID being flushed, the first device may not send the MAC PDU to the second device based on the second SL grant, and the first device may not send the SL HARQ feedback information related to the MAC PDU to the base station based on the second PUCCH resource.

[0261] Based on various embodiments of the present disclosure, if the sending UE performs SL communication based on the SL CG allocated by the base station, and if the number of transmissions performed by the sending UE based on the SL CG reaches the maximum number of transmissions preconfigured for the UE, the UE can refresh the buffer of the associated SL HARQ process. In addition, in this case, if the sending UE reports NACK information (received from the receiving UE) to the base station based on the PUCCH resources related to the SL CG, and if the base station allocates a DG for retransmission to the sending UE based on the NACK information, the sending UE can ignore the retransmission resources allocated by the DG, and the sending UE may not send HARQ feedback to the base station based on the PUCCH resources related to the DG. Herein, for example, the maximum number of transmissions can be configured for the UE for each SL CG.

[0262] Various embodiments of the present disclosure may be combined with each other.

[0263] Hereinafter, devices to which various embodiments of the present disclosure can be applied will be described.

[0264] The various descriptions, functions, processes, proposals, methods and / or operational flows of the present disclosure described in this document may be applied to, but not limited to, various fields requiring wireless communication / connection between devices (e.g., 5G).

[0265] Hereinafter, a description will be given in more detail with reference to the accompanying drawings. In the following drawings / descriptions, unless otherwise described, the same reference numerals may represent the same or corresponding hardware blocks, software blocks or functional blocks.

[0266] Fig.17 A communication system 1 according to an embodiment of the present disclosure is shown.

[0267] Reference Fig.17 , the communication system 1 to which various embodiments of the present disclosure are applied includes a wireless device, a base station (BS), and a network. Herein, a wireless device refers to a device that performs communication using a radio access technology (RAT) (e.g., 5G new RAT (NR) or long term evolution (LTE)), and may be referred to as a communication / radio / 5G device. The wireless device may include, but is not limited to, a robot 100a, a vehicle 100b-1, 100b-2, an extended reality (XR) device 100c, a handheld device 100d, a home appliance 100e, an Internet of Things (IoT) device 100f, and an artificial intelligence (AI) device / server 400. For example, a vehicle may include a vehicle with a wireless communication function, an autonomous vehicle, and a vehicle capable of performing inter-vehicle communication. Herein, a vehicle may include an unmanned aerial vehicle (UAV) (e.g., a drone). The XR device may include an augmented reality (AR) / virtual reality (VR) / mixed reality (MR) device and may be implemented in the form of a head mounted device (HMD), a head up display (HUD) installed in a vehicle, a television, a smart phone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, and the like. Handheld devices may include smart phones, smart boards, wearable devices (e.g., smart watches or smart glasses), and computers (e.g., notebooks). Home appliances may include TVs, refrigerators, and washing machines. IoT devices may include sensors and smart meters. For example, BSs and networks may be implemented as wireless devices, and a specific wireless device 200a may operate as a BS / network node relative to other wireless devices.

[0268] Here, in addition to LTE, NR and 6G, the wireless communication technology implemented in the wireless devices 100a to 100f of the present disclosure may also include a narrowband Internet of Things for low-power communication. In this case, for example, the NB-IoT technology may be an example of a low-power wide area network (LPWAN) technology, and may be implemented as a standard 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 wireless devices 100a to 100f of the present disclosure may perform communication based on the LTE-M technology. In this case, as an example, the LTE-M technology may be an example of an LPWAN, and may be referred to as various names including enhanced machine type communication (eMTC), etc. For example, the LTE-M technology may be implemented as at least any one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-bandwidth limited (non-BL), 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 implemented in the wireless devices 100a to 100f of the present disclosure may include at least one of Bluetooth, a low power wide area network (LPWAN), and ZigBee considering low power communication, and is not limited to the above names. As an example, the ZigBee technology may generate a personal area network (PAN) related to small / low power digital communication based on various standards including IEEE 802.15.4, etc., and may be referred to as various names.

[0269] The wireless devices 100a to 100f may be connected to the network 300 via the BS 200. AI technology may be applied to the wireless devices 100a to 100f, and the wireless devices 100a to 100f may be connected to the AI ​​server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network. Although the wireless devices 100a to 100f may communicate with each other via the BS 200 / network 300, the wireless devices 100a to 100f may perform direct communication (e.g., side link communication) with each other without going through the BS / network. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). An IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., a sensor) or other wireless devices 100a to 100f.

[0270] Wireless communication / connection 150a, 150b or 150c can be established between wireless devices 100a to 100f / BS 200 or BS200 / BS 200. Here, the wireless communication / connection can be established through various RATs (e.g., 5G NR) such as uplink / downlink communication 150a, sidelink communication 150b (or D2D communication) or inter-BS communication (e.g., relay, integrated access backhaul (IAB)). The wireless device and the BS / wireless device can send / receive radio signals to / from each other through wireless communication / connection 150a and 150b. For example, wireless communication / connection 150a and 150b can send / receive signals through various physical channels. To this end, various configuration information configuration processes for sending / receiving radio signals, various signal processing processes (e.g., channel coding / decoding, modulation / demodulation and resource mapping / demapping), and at least a portion of the resource allocation process can be performed based on various proposals of the present disclosure.

[0271] Fig.18 A wireless device according to an embodiment of the present disclosure is shown.

[0272] Reference Fig.18 , the first wireless device 100 and the second wireless device 200 may transmit radio signals via various RATs (e.g., LTE and NR). Herein, {the first wireless device 100 and the second wireless device 200} may correspond to Fig.17 {wireless device 100x and BS200} and / or {wireless device 100x and wireless device 100x} in.

[0273] The first wireless device 100 may include one or more processors 102 and one or more memories 104, and may additionally further include one or more transceivers 106 and / or one or more antennas 108. The (one or more) processors 102 may control the (one or more) memories 104 and / or the (one or more) transceivers 106, and may be configured to implement the descriptions, functions, processes, proposals, methods and / or operation flows disclosed in this document. For example, the (one or more) processors 102 may process the information in the (one or more) memories 104 to generate first information / signals, and then transmit a radio signal including the first information / signals through the (one or more) transceivers 106. The (one or more) processors 102 may receive a radio signal including a second information / signal through the transceiver 106, and then store the information obtained by processing the second information / signals in the (one or more) memories 104. The (one or more) memories 104 may be connected to the (one or more) processors 102, and may store various information related to the operation of the (one or more) processors 102. For example, (one or more) memories 104 may store software code including commands for executing part or all of the processing controlled by (one or more) processors 102 or for executing the descriptions, functions, processes, proposals, methods and / or operational flows disclosed in this document. Here, (one or more) processors 102 and (one or more) memories 104 may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). (One or more) transceivers 106 may be connected to (one or more) processors 102 and send and / or receive radio signals through (one or more) antennas 108. Each transceiver 106 may include a transmitter and / or a receiver. (One or more) transceivers 106 may be used interchangeably with (one or more) radio frequency (RF) units. In the present disclosure, a wireless device may represent a communication modem / circuit / chip.

[0274] The second wireless device 200 may include one or more processors 202 and one or more memories 204, and may additionally further include one or more transceivers 206 and / or one or more antennas 208. The (one or more) processors 202 may control the (one or more) memories 204 and / or the (one or more) transceivers 206, and may be configured to implement the descriptions, functions, processes, proposals, methods and / or operation flows disclosed in this document. For example, the (one or more) processors 202 may process the information in the (one or more) memories 204 to generate third information / signals, and then transmit a radio signal including the third information / signals through the (one or more) transceivers 206. The (one or more) processors 202 may receive a radio signal including fourth information / signals through the (one or more) transceivers 106, and then store the information obtained by processing the fourth information / signals in the (one or more) memories 204. The (one or more) memories 204 may be connected to the (one or more) processors 202, and may store various information related to the operation of the (one or more) processors 202. For example, (one or more) memories 204 may store software code including commands for executing part or all of the processing controlled by (one or more) processors 202 or for executing the descriptions, functions, processes, proposals, methods and / or operational flows disclosed in this document. Here, (one or more) processors 202 and (one or more) memories 204 may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). (One or more) transceivers 206 may be connected to (one or more) processors 202 and transmit and / or receive radio signals through (one or more) antennas 208. Each transceiver 206 may include a transmitter and / or a receiver. (One or more) transceivers 206 may be used interchangeably with (one or more) RF units. In the present disclosure, a wireless device may represent a communication modem / circuit / chip.

[0275] Below, the hardware elements of the wireless devices 100 and 200 will be described in more detail. One or more protocol layers may be implemented by, but are not limited to, one or more processors 102 and 202. For example, one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, and SDAP). One or more processors 102 and 202 may generate one or more protocol data units (PDUs) and / or one or more service data units (SDUs) according to the descriptions, functions, processes, proposals, methods, and / or operating procedures disclosed in this document. One or more processors 102 and 202 may generate messages, control information, data, or information according to the descriptions, functions, processes, proposals, methods, and / or operating procedures disclosed in this document. One or more processors 102 and 202 may generate a signal (e.g., a baseband signal) including a PDU, SDU, message, control information, data, or information according to the description, function, process, proposal, method, and / or operation flow disclosed in this document, and provide the generated signal to one or more transceivers 106 and 206. One or more processors 102 and 202 may receive a signal (e.g., a baseband signal) from one or more transceivers 106 and 206, and obtain the PDU, SDU, message, control information, data, or information according to the description, function, process, proposal, method, and / or operation flow disclosed in this document.

[0276] One or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors or microcomputers. One or more processors 102 and 202 may be implemented by hardware, firmware, software or a combination thereof. For 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 one or more processors 102 and 202. The descriptions, functions, processes, proposals, methods and / or operational flows disclosed in this document may be implemented using firmware or software, and the firmware or software may be configured to include modules, processes or functions. Firmware or software configured to perform the descriptions, functions, processes, proposals, methods and / or operational flows disclosed in this document may be included in one or more processors 102 and 202 or stored in one or more memories 104 and 204, thereby being driven by one or more processors 102 and 202. The descriptions, functions, processes, proposals, methods and / or operational flows disclosed in this document may be implemented using software or firmware in the form of codes, commands and / or command sets.

[0277] One or more memories 104 and 204 may be connected to one or more processors 102 and 202 and may store various types of data, signals, messages, information, programs, codes, instructions, and / or commands. One or more memories 104 and 204 may be composed of read-only memory (ROM), random access memory (RAM), electrically erasable programmable read-only memory (EPROM), flash memory, hard drive, register, cash memory, computer-readable storage medium, and / or a combination thereof. One or more memories 104 and 204 may be located inside and / or outside one or more processors 102 and 202. One or more memories 104 and 204 may be connected to one or more processors 102 and 202 via various technologies such as wired or wireless connections.

[0278] One or more transceivers 106 and 206 may send user data, control information and / or radio signals / channels mentioned in the method and / or operation flow of this document to one or more other devices. One or more transceivers 106 and 206 may receive user data, control information and / or radio signals / channels mentioned in the description, function, process, proposal, method and / or operation flow disclosed in this document from one or more other devices. For example, one or more transceivers 106 and 206 may be connected to one or more processors 102 and 202, and may send and receive radio signals. For example, one or more processors 102 and 202 may perform control so that one or more transceivers 106 and 206 may send user data, control information or radio signals to one or more other devices. One or more processors 102 and 202 may perform control so that one or more transceivers 106 and 206 may receive user data, control information or radio signals from one or more other devices. One or more transceivers 106 and 206 may be connected to one or more antennas 108 and 208, and one or more transceivers 106 and 206 may be configured to send and receive user data, control information, and / or radio signals / channels mentioned in the description, functions, processes, proposals, methods, and / or operation flows disclosed in this document through one or more antennas 108 and 208. In this document, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers 106 and 206 may convert received radio signals / channels, etc. from RF band signals to baseband signals to process received user data, control information, radio signals / channels, etc. using one or more processors 102 and 202. One or more transceivers 106 and 206 may convert user data, control information, radio signals / channels, etc. processed using one or more processors 102 and 202 from baseband signals to RF band signals. To this end, one or more of the transceivers 106 and 206 may include (analog) oscillators and / or filters.

[0279] Fig.19 A signal processing circuit for transmitting a signal according to an embodiment of the present disclosure is shown.

[0280] Reference Fig.19 The signal processing circuit 1000 may include a scrambler 1010, a modulator 1020, a layer mapper 1030, a precoder 1040, a resource mapper 1050, and a signal generator 1060. Fig.19 Operation / function, not limited to Fig.18 The processor 102, 202 and / or the transceiver 106, 206 of Fig.18The processor 102, 202 and / or the transceiver 106, 206 are implemented Fig.19 For example, you can Fig.18 The processor 102, 202 of the embodiment of the present invention implements the blocks 1010 to 1060. Alternatively, the Fig.18 The processor 102, 202 implements blocks 1010 to 1050 and can be Fig.18 The transceiver 106, 206 of the embodiment implements the block 1060.

[0281] Can be through Fig.19 The signal processing circuit 1000 converts the codeword into a radio signal. Herein, the codeword is a coded bit sequence of an information block. The information block may include a transport block (e.g., UL-SCH transport block, DL-SCH transport block). The radio signal may be transmitted through various physical channels (e.g., PUSCH and PDSCH).

[0282] Specifically, the codeword can be converted into a scrambled bit sequence by the scrambler 1010. The scrambling sequence for scrambling can be generated based on an initial value, and the initial value can include the ID information of the wireless device. The scrambled bit sequence can be modulated into a modulation symbol sequence by the modulator 1020. The modulation scheme may include pi / 2-binary phase shift keying (pi / 2-BPSK), m-phase shift keying (m-PSK) and m-quadrature amplitude modulation (m-QAM). The complex modulation symbol sequence can be mapped to one or more transmission layers by the layer mapper 1030. The modulation symbol of each transmission layer can be mapped (precoded) to (one or more) corresponding antenna ports by the precoder 1040. The output z of the precoder 1040 can be obtained by multiplying the output y of the layer mapper 1030 with the N*M precoding matrix W. Here, N is the number of antenna ports and M is the number of transmission layers. The precoder 1040 can perform precoding after performing transform precoding (e.g., DFT) for the complex modulation symbol. Alternatively, the precoder 1040 may perform precoding without performing transform precoding.

[0283] The resource mapper 1050 may map the modulation symbols of each antenna port to time-frequency resources. The time-frequency resources may include multiple symbols in the time domain (e.g., CP-OFDMA symbols and DFT-s-OFDMA symbols) and multiple subcarriers in the frequency domain. The signal generator 1060 may generate a radio signal from the mapped modulation symbols, and the generated radio signal may be sent to other devices through each antenna. To this end, the signal generator 1060 may include an inverse fast Fourier transform (IFFT) module, a cyclic prefix (CP) inserter, a digital-to-analog converter (DAC), and an up-converter.

[0284] Can be used with Fig.19 The signal processing process for a signal received in the wireless device is configured in the reverse manner of the signal processing processes 1010 to 1060. For example, a wireless device (e.g., Fig.18 100, 200) can receive a radio signal from the outside through an antenna port / transceiver. The received radio signal can be converted into a baseband signal by a signal restorer. To this end, the signal restorer may include a frequency downlink converter, an analog-to-digital converter (ADC), a CP remover, and a fast Fourier transform (FFT) module. Next, the baseband signal can be restored to a codeword through a resource demapping process, a post-coding process, a demodulation processor, and a descrambling process. The codeword can be restored to the original information block by decoding. Therefore, a signal processing circuit (not illustrated) for receiving a signal may include a signal restorer, a resource demapper, a post-encoder, a demodulator, a descrambler, and a decoder.

[0285] Fig. 20 Another example of a wireless device based on an embodiment of the present disclosure is shown. The wireless device can be implemented in various forms according to use cases / services (see Fig.17 ).

[0286] Reference Fig. 20 , the wireless devices 100, 200 may correspond to Fig.18 The wireless devices 100 and 200 may be configured by various elements, components, units / portions and / or modules. For example, each of the wireless devices 100 and 200 may include a communication unit 110, a control unit 120, a memory unit 130 and an additional component 140. The communication unit may include a communication circuit 112 and (one or more) transceivers 114. For example, the communication circuit 112 may include Fig.18 One or more processors 102, 202 and / or one or more memories 104, 204. For example, the transceiver(s) 114 may include Fig.18 The control unit 120 is electrically connected to the communication unit 110, the memory 130, and the additional components 140, and controls the overall operation of the wireless device. For example, the control unit 120 can control the electrical / mechanical operation of the wireless device based on the program / code / command / information stored in the memory unit 130. The control unit 120 can send the information stored in the memory unit 130 to the outside (e.g., other communication devices) via the communication unit 110 through a wireless / wired interface, or store the information received from the outside (e.g., other communication devices) via the communication unit 110 through a wireless / wired interface in the memory unit 130.

[0287] The additional component 140 may be configured in various ways depending on the type of wireless device. For example, the additional component 140 may include at least one of a power unit / battery, an input / output (I / O) unit, a drive unit, and a computing unit. The wireless device may be implemented in the following forms without limitation: a robot ( Fig.17 100a), vehicles ( Fig.17 100b-1 and 100b-2), XR devices ( Fig.17 100c), handheld devices ( Fig.17 100d), household appliances ( Fig.17 100e), IoT devices ( Fig.17 100f), digital broadcasting terminals, hologram equipment, public safety equipment, MTC equipment, medical equipment, fintech equipment (or financial equipment), security equipment, climate / environmental equipment, AI servers / equipment ( Fig.17 400), BS( Fig.17 200), network nodes, etc. Depending on the use case / service, the wireless device can be used in a mobile or fixed place.

[0288] exist Fig. 20 In the wireless device 100, 200, various elements, components, units / parts and / or modules in the wireless device 100, 200 can all be connected to each other through a wired interface, or at least part of them can be wirelessly connected through the communication unit 110. For example, in each of the wireless devices 100, 200, the control unit 120 and the communication unit 110 can be connected by wire, and the control unit 120 and the first unit (e.g., 130, 140) can be wirelessly connected through the communication unit 110. Each element, component, unit / part and / or module within the wireless device 100, 200 can also include one or more elements. For example, the control unit 120 can be constructed by a set of one or more processors. As an example, the control unit 120 can be constructed by a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphics processing unit, and a memory control processor. As another example, the memory 130 can be constructed by a random access memory (RAM), a dynamic RAM (DRAM), a read-only memory (ROM), a flash memory, a volatile memory, a non-volatile memory, and / or a combination thereof.

[0289] Hereinafter, the implementation will be described in detail with reference to the accompanying drawings. Fig. 20 .

[0290] Fig.21A handheld device based on an embodiment of the present disclosure is shown. The handheld device may include a smart phone, a smart board, a wearable device (e.g., a smart watch or smart glasses), or a portable computer (e.g., a notebook). The handheld device may be referred to as a mobile station (MS), a user terminal (UT), a mobile subscriber station (MSS), a subscriber station (SS), an advanced mobile station (AMS), or a wireless terminal (WT).

[0291] Reference Fig.21 , the handheld device 100 may include an antenna unit 108, a communication unit 110, a control unit 120, a memory unit 130, a power supply unit 140a, an interface unit 140b, and an I / O unit 140c. The antenna unit 108 may be configured as a part of the communication unit 110. Blocks 110 to 130 / 140a to 140c correspond to Fig. 20 Frame 110 to 130 / 140.

[0292] The communication unit 110 may send and receive signals (e.g., data signals and control signals) to and from other wireless devices or BSs. The control unit 120 may perform various operations by controlling the constituent elements of the handheld device 100. The control unit 120 may include an application processor (AP). The memory unit 130 may store data / parameters / programs / codes / commands required to drive the handheld device 100. The memory unit 130 may store input / output data / information. The power supply unit 140a may supply power to the handheld device 100 and include a wired / wireless charging circuit, a battery, etc. The interface unit 140b may support the connection of the handheld device 100 to other external devices. The interface unit 140b may include various ports (e.g., audio I / O ports and video I / O ports) for connecting to external devices. The I / O unit 140c may input or output video information / signals, audio information / signals, data and / or information input by a user. The I / O unit 140c may include a camera, a microphone, a user input unit, a display unit 140d, a speaker and / or a tactile module.

[0293] For example, in the case of data communication, the I / O unit 140c can obtain information / signals (e.g., touch, text, voice, image, or video) input by the user, and the obtained information / signals can be stored in the memory unit 130. The communication unit 110 can convert the information / signals stored in the memory into radio signals, and directly send the converted radio signals to other wireless devices or to the BS. The communication unit 110 can receive radio signals from other wireless devices or BSs, and then restore the received radio signals to the original information / signals. The restored information / signals can be stored in the memory unit 130, and can be output as various types (e.g., text, voice, image, video, or tactile) through the I / O unit 140.

[0294] Fig. 22 A vehicle or autonomous vehicle based on an embodiment of the present disclosure is shown. The vehicle or autonomous vehicle can be implemented by a mobile robot, a car, a train, a manned / unmanned aerial vehicle (AV), a ship, etc.

[0295] Reference Fig. 22 , the vehicle or autonomous vehicle 100 may include an antenna unit 108, a communication unit 110, a control unit 120, a drive unit 140a, a power supply unit 140b, a sensor unit 140c, and an autonomous driving unit 140d. The antenna unit 108 may be configured as a part of the communication unit 110. Blocks 110 / 130 / 140a to 140d correspond to Fig. 20 Frame 110 / 130 / 140.

[0296] The communication unit 110 may send and receive signals (e.g., data signals and control signals) to and from external devices such as other vehicles, BSs (e.g., gNBs and roadside units), and servers. The control unit 120 may perform various operations by controlling elements of the vehicle or autonomous vehicle 100. The control unit 120 may include an electronic control unit (ECU). The drive unit 140a may cause the vehicle or autonomous vehicle 100 to travel on the road. The drive unit 140a may include an engine, a motor, a transmission system, wheels, brakes, a steering device, etc. The power supply unit 140b may supply power to the vehicle or autonomous vehicle 100, and may include a wired / wireless charging circuit, a battery, etc. The sensor unit 140c may acquire vehicle status, external environment information, user information, etc. The sensor unit 140c may include an inertial measurement unit (IMU) sensor, a collision sensor, a wheel sensor, a speed sensor, a slope sensor, a weight sensor, a heading sensor, a position module, a vehicle forward / reverse sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, a lighting sensor, a pedal position sensor, etc. The autonomous driving unit 140d may implement a technology for maintaining a lane in which the vehicle is traveling, a technology for automatically adjusting a speed (e.g., adaptive cruise control), a technology for autonomously driving along a determined path, a technology for driving by automatically setting a path when a destination is set, and the like.

[0297] For example, the communication unit 110 may receive map data, traffic information data, etc. from an external server. The autonomous driving unit 140d may generate an autonomous driving path and a driving plan from the acquired data. The control unit 120 may control the drive unit 140a so that the vehicle or the autonomous driving vehicle 100 may move along the autonomous driving path according to the driving plan (e.g., speed / direction control). In the middle of autonomous driving, the communication unit 110 may aperiodically / periodically acquire the most recent traffic information data from an external server and acquire surrounding traffic information data from adjacent vehicles. In the middle of autonomous driving, the sensor unit 140c may acquire vehicle status and / or surrounding environment information. The autonomous driving unit 140d may update the autonomous driving path and driving plan based on the newly acquired data / information. The communication unit 110 may transmit information about the vehicle position, autonomous driving path, and / or driving plan to an external server. The external server may predict traffic information data using AI technology, etc. based on information collected from the vehicle or autonomous driving vehicle, and provide the predicted traffic information data to the vehicle or autonomous driving vehicle.

[0298] The claims in this specification may be combined in various ways. For example, the technical features in the method claims of this specification may be combined to be implemented or performed in a device, and the technical features in the device claims may be combined to be implemented or performed in a method. In addition, the technical features in (one or more) method claims and (one or more) device claims may be combined to be implemented or performed in a device. In addition, the technical features in (one or more) method claims and (one or more) device claims may be combined to be implemented or performed in a method.

Claims

1. A method for performing wireless communication by a first device, the method comprising the following steps: receiving, from a base station, information about a first sidelink SL grant and information about a maximum number of times a medium access control MAC protocol data unit PDU can be sent using the first SL grant; sending the MAC PDU to the second device based on the first SL grant and the SL process; Refreshing a hybrid automatic repeat request HARQ buffer associated with the SL process based on the number of transmissions of the MAC PDU reaching the maximum number; as well as receiving a second SL grant for retransmission of the MAC PDU from the base station via a physical downlink control channel (PDCCH), wherein the second SL grant is related to the SL process in which the HARQ buffer is empty, Wherein, based on that the second SL grant is related to the SL process in which the HARQ buffer is empty, the first device ignores the second SL grant and skips the SL HARQ feedback transmission related to the MAC PDU on the physical uplink control channel PUCCH resources related to the second SL grant.

2. The method according to claim 1, wherein: The SL process is associated with a SL process ID associated with the MAC PDU, and the SL process ID is sent to the second device based on sidelink control information SCI sent through a physical sidelink shared channel PSSCH.

3. The method according to claim 1, wherein: The first SL license is a SL configuration license CG, and the SL CG is one of a first type SLCG or a second type SL CG.

4. The method according to claim 1, further comprising the steps of: sending NACK information related to the MAC PDU to the base station based on the PUCCH resources related to the first SL grant, Wherein, the second SL grant is received from the base station based on the NACK information.

5. The method according to claim 1, further comprising the steps of: Based on the transmission number of the MAC PDU reaching the maximum number, ACK information related to the MAC PDU is sent to the base station.

6. The method according to claim 1, wherein: Based on the first device receiving ACK information related to the MAC PDU from the second device through the physical side link feedback channel PSFCH, the HARQ buffer related to the SL process is refreshed.

7. The method according to claim 1, wherein: Based on the first device sending ACK information related to the MAC PDU to the base station, the HARQ buffer related to the SL process is refreshed.

8. The method according to claim 1, wherein: Based on the first device setting the field related to HARQ feedback in the SCI related to the MAC PDU reaching the maximum number to be enabled, the HARQ buffer related to the SL process is refreshed.

9. The method according to claim 1, wherein: The HARQ buffer related to the SL process is refreshed based on (i) the first device sending NACK information related to the MAC PDU to the base station and (ii) downlink control information DCI related to the second SL grant includes a switched new data indicator NDI.

10. The method according to claim 1, wherein: The HARQ buffer associated with the SL process is refreshed based on (i) the first device sending ACK information related to the MAC PDU to the base station and (ii) downlink control information DCI related to the second SL grant includes a non-switched new data indicator NDI.

11. The method according to claim 1, wherein: The maximum number is determined based on at least one priority level of at least one logical channel associated with the MAC PDU.

12. The method according to claim 11, wherein: The maximum number is related to a highest priority among the at least one priority of the at least one logical channel.

13. A first device configured to perform wireless communication, the first device comprising: at least one transceiver; at least one processor; as well as at least one memory connected to the at least one processor and storing instructions, the instructions being executed to cause the first device to perform the following operations: receiving, from a base station, information about a first sidelink SL grant and information about a maximum number of times a medium access control MAC protocol data unit PDU can be sent using the first SL grant; sending the MAC PDU to the second device based on the first SL grant and the SL process; Refreshing a hybrid automatic repeat request HARQ buffer associated with the SL process based on the number of transmissions of the MAC PDU reaching the maximum number; as well as receiving a second SL grant for retransmission of the MAC PDU from the base station via a physical downlink control channel (PDCCH), wherein the second SL grant is related to the SL process in which the HARQ buffer is empty, Wherein, based on that the second SL grant is related to the SL process in which the HARQ buffer is empty, the first device ignores the second SL grant and skips the SL HARQ feedback transmission related to the MAC PDU on the physical uplink control channel PUCCH resources related to the second SL grant.

14. A processing device configured to control a first device, the processing device comprising: at least one processor; as well as at least one memory connected to the at least one processor and storing instructions, the instructions being executed to cause the first device to perform the following operations: receiving, from a base station, information about a first sidelink SL grant and information about a maximum number of times a medium access control MAC protocol data unit PDU can be sent using the first SL grant; sending the MAC PDU to the second device based on the first SL grant and the SL process; Refreshing a hybrid automatic repeat request HARQ buffer associated with the SL process based on the number of transmissions of the MAC PDU reaching the maximum number; as well as receiving a second SL grant for retransmission of the MAC PDU from the base station via a physical downlink control channel (PDCCH), wherein the second SL grant is related to the SL process in which the HARQ buffer is empty, Wherein, based on that the second SL grant is related to the SL process in which the HARQ buffer is empty, the first device ignores the second SL grant and skips the SL HARQ feedback transmission related to the MAC PDU on the physical uplink control channel PUCCH resources related to the second SL grant.

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