Method and apparatus for sidelink communication in an unlicensed band

Abstract

A method and apparatus for sidelink communication in an unlicensed band are disclosed. The method of the first terminal includes receiving an SCI from a second terminal, receiving data scheduled by the SCI from the second terminal, generating a HARQ-ACK for the data, and performing a first LBT operation for transmission of the HARQ-ACK in a first PSFCH occasion among N PSFCH occasions set for the first terminal.

Description

Technical Field

[0001] The present disclosure relates to sidelink communication technology, and more particularly to technology for sidelink communication in an unlicensed band.

Background Art

[0002] For the processing of rapidly increasing wireless data, a communication system (e.g., a NR (new radio) communication system) using a frequency band higher than the frequency band of an LTE (long term evolution) communication system (or an LTE-A communication system) (e.g., a frequency band of 6 GHz or higher) is considered. The NR communication system can support not only a frequency band of 6 GHz or higher but also a frequency band of 6 GHz or lower, and can support various communication services and scenarios compared to the LTE communication system. Also, the requirements of the NR communication system can include eMBB (enhanced Mobile BroadBand), URLLC (Ultra Reliable Low Latency Communication), mMTC (massive Machine Type Communication), etc.

[0003] On the other hand, SL (sidelink) communication can be performed in an unlicensed band. A first terminal can transmit data to a second terminal in an unlicensed band, and the second terminal can transmit a HARQ-ACK (hybrid automatic repeat request-acknowledgement) for the data to the first terminal. To transmit the HARQ-ACK in an unlicensed band, the second terminal can perform an LBT (listen before talk) operation. If the LBT operation fails, the second terminal may not be able to transmit the HARQ-ACK to the first terminal. In this case, since the reliability of the communication system decreases, a method for solving the above problem is required.

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present disclosure for solving the above problems is to provide a method and an apparatus for sidelink communication in an unlicensed band.

Means for Solving the Problems

[0005] A method of a first terminal according to a first embodiment of the present disclosure for achieving the above object includes a step of receiving an SCI from a second terminal, a step of receiving data scheduled by the SCI from the second terminal, a step of generating a HARQ-ACK for the data, and a step of performing a first LBT operation for transmission of the HARQ-ACK in a first PSFCH occasion among N PSFCH occasions set in the first terminal, where N is a natural number.

[0006] The N PSFCH occasions may include the first PSFCH occasion and N-1 PSFCH occasions, and the first PSFCH occasion and the N-1 PSFCH occasions may be set by one message or independently set by different messages from each other.

[0007] The SCI may include first information indicating whether the N PSFCH occasions are applicable. When the first information indicates that the N PSFCH occasions are applicable, the N PSFCH occasions may be used for transmission of the HARQ-ACK. When the first information indicates that the N PSFCH occasions are not applicable, only the first PSFCH occasion may be used for transmission of the HARQ-ACK.

[0008] When the first terminal cannot transmit the HARQ-ACK within the COT, the N PSFCH occasions may be used for transmission of the HARQ-ACK.

[0009] The method of the first terminal may further include, when the first LBT operation fails, performing a second LBT operation for transmitting the HARQ-ACK in the second PSFCH occasion among the N PSFCH occasions, and when the second LBT operation is successful, transmitting a PSFCH format including the HARQ-ACK to the second terminal in the second PSFCH occasion.

[0010] The PSFCH format may be repeatedly transmitted in the frequency domain.

[0011] The method of the first terminal may further include transmitting a first signal, and the transmission of the PSFCH format and the transmission of the first signal may be multiplexed in the frequency domain. The transmission of the PSFCH format may be performed on dedicated RBs within the frequency domain, and the transmission of the first signal may be performed on common RBs within the frequency domain.

[0012] The transmission of the first signal on the common RBs may be performed when the frequency interval between the dedicated RBs and the common RBs exceeds a threshold value.

[0013] The method of the first terminal may further include transmitting a first signal on common RBs to maintain COT.

[0014] The method of the second terminal according to the second embodiment of the present disclosure for achieving the above object includes transmitting an SCI to the first terminal, transmitting data scheduled by the SCI to the first terminal, and performing a monitoring operation for one or more PSFCH occasions among the N PSFCH occasions set for the first terminal to receive a HARQ-ACK for the data, where N is a natural number.

[0015] The N PSFCH occasions can include the first PSFCH occasion and N - 1 PSFCH occasions, and the first PSFCH occasion and the N - 1 PSFCH occasions can be set by one message or independently set by different messages from each other.

[0016] The SCI can include first information indicating the applicability of the N PSFCH occasions. When the first information indicates that the N PSFCH occasions are applicable, the N PSFCH occasions can be used for the transmission of the HARQ - ACK. When the first information indicates that the N PSFCH occasions are not applicable, only the first PSFCH occasion can be used for the transmission of the HARQ - ACK.

[0017] If the first terminal cannot transmit the HARQ - ACK within the COT, the N PSFCH occasions can be used for the transmission of the HARQ - ACK.

[0018] The method of the second terminal can further include receiving, from the first terminal, a PSFCH format including the HARQ - ACK based on the monitoring operation.

[0019] The PSFCH format can be repeatedly received in the frequency domain or received in dedicated RBs within the frequency domain.

[0020] The first terminal according to the third embodiment of the present disclosure for achieving the above object includes a processor, and the processor causes the first terminal to receive an SCI from a second terminal, receive data scheduled by the SCI from the second terminal, generate a HARQ - ACK for the data, and perform a first LBT operation for the transmission of the HARQ - ACK in the first PSFCH occasion among the N PSFCH occasions set for the first terminal, where N is a natural number.

[0021] The SCI may include first information indicating whether the N PSFCH occasions are applied. When the first information indicates that the N PSFCH occasions are applied, the N PSFCH occasions may be used for transmitting the HARQ-ACK. When the first information indicates that the N PSFCH occasions are not applied, only the first PSFCH occasion may be used for transmitting the HARQ-ACK.

[0022] When the first terminal is unable to transmit the HARQ-ACK within the COT, the N PSFCH occasions may be used for transmitting the HARQ-ACK.

[0023] The processor may further cause the first terminal to perform a second LBT operation for transmitting the HARQ-ACK on a second PSFCH occasion among the N PSFCH occasions when the first LBT operation fails, and when the second LBT operation is successful, further cause the second PSFCH occasion to transmit a PSFCH format including the HARQ-ACK to the second terminal.

[0024] The processor may further cause the first terminal to transmit a first signal. The transmission of the PSFCH format and the transmission of the first signal may be multiplexed in the frequency domain. The transmission of the PSFCH format may be performed on dedicated RBs within the frequency domain, and the transmission of the first signal may be performed on common RBs within the frequency domain.

Advantages of the Invention

[0025] According to the present disclosure, a plurality of PSFCH (physical sidelink feedback channel) occasions can be configured. A terminal can perform a first LBT (listen before talk) operation to perform PSFCH transmission on the first PSFCH occasion among the plurality of PSFCH occasions. If the first LBT operation fails, the terminal can perform a second LBT operation to perform PSFCH transmission on the second PSFCH occasion among the plurality of PSFCH occasions. According to the method, since a plurality of LBT operations can be performed for PSFCH transmission, PSFCH transmission can be guaranteed.

[0026] The PSFCH format can be repeatedly transmitted in the frequency domain. Transmission of the PSFCH format and transmission of any signal in the frequency domain can be multiplexed. According to the method, the OCB (Occupied Channel Bandwidth) regulation can be satisfied.

Brief Description of the Drawings

[0027]

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[0028] While the present disclosure can be modified in various ways and can have various embodiments, specific embodiments will be illustrated in the drawings and described in detail herein. However, this is not intended to limit the present disclosure to the specific embodiments, and it should be understood to include all modifications, equivalents, or alternatives included in the spirit and technical scope of the present disclosure.

[0029] The terms first, second, etc. can be used to describe various components, but the components should not be limited by these terms. These terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the rights of the present disclosure, the first component can be named the second component, and similarly, the second component can be named the first component. The term "and / or" includes combinations of a plurality of related listed items or any one of a plurality of related listed items.

[0030] In an embodiment of the present disclosure, "at least one of A and B" can mean "at least one of A or B" or "at least one of one or more combinations of A and B". Also, in an embodiment of the present disclosure, "one or more of A and B" can mean "one or more of A or B" or "one or more of one or more combinations of A and B".

[0031] When it is mentioned that a certain component is "connected to" or "attached to" another component, it should be understood that it may be directly connected to or attached to the other component, or there may be other components in between. On the contrary, when it is mentioned that a certain component is "directly connected to" or "directly attached to" another component, it should be understood that there are no other components in between.

[0032] The terms used in this disclosure are merely used to describe specific embodiments and are not intended to limit this disclosure. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this disclosure, terms such as "including" or "having" are intended to specify the presence of the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should not be construed as precluding the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0033] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an idealized or overly formal sense unless clearly defined in this disclosure.

[0034] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present disclosure will be described in more detail. In describing the present disclosure, the same reference numerals are used for the same components in the drawings to facilitate overall understanding, and duplicate descriptions of the same components are omitted.

[0035] A communication system to which embodiments according to the present disclosure are applied will be described. The communication system can be a 4G communication system (e.g., an LTE (long-term evolution) communication system, an LTE-A communication system), a 5G communication system (e.g., an NR (new radio) communication system), a 6G communication system, etc. The 4G communication system can support communication in a frequency band of 6 GHz or less, and the 5G communication system can support communication not only in a frequency band of 6 GHz or less but also in a frequency band of 6 GHz or more. The communication system to which embodiments according to the present disclosure are applied is not limited to the content described below, and the embodiments according to the present disclosure can be applied to various communication systems. Here, the communication system can be used in the same meaning as a communication network, "LTE" can indicate "4G communication system", "LTE communication system" or "LTE-A communication system", and "NR" can indicate "5G communication system" or "NR communication system".

[0036] In the embodiment, "an operation (e.g., a transmission operation) is set" may mean that "configuration information for the corresponding operation (e.g., an information element, a parameter)" and / or "information indicating the execution of the corresponding operation" is signaled. "An information element (e.g., a parameter) is set" may mean that the corresponding information element is signaled. The signaling can be at least one of SI (system information) signaling (e.g., transmission of an SIB (system information block) and / or an MIB (master information block)), RRC signaling (e.g., transmission of RRC parameters and / or upper layer parameters), MAC CE (control element) signaling, or PHY signaling (e.g., transmission of DCI (downlink control information), UCI (uplink control information), and / or SCI (sidelink control information)).

[0037] In the present disclosure, when a method (e.g., signal transmission or reception) performed by a first communication node among communication nodes is described, a second communication node corresponding thereto can perform a method corresponding to the method performed by the first communication node (e.g., signal reception or transmission). For example, when the operation of a terminal is described, a base station corresponding to the terminal can perform an operation corresponding to the operation of the terminal. Conversely, when the operation of a base station is described, a terminal corresponding to the base station can perform an operation corresponding to the operation of the base station. Also, when the operation of a first terminal is described, a second terminal corresponding to the first terminal can perform an operation corresponding to the operation of the first terminal. Conversely, when the operation of a second terminal is described, a first terminal corresponding to the second terminal can perform an operation corresponding to the operation of the second terminal.

[0038] FIG. 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0039] Referring to FIG. 1, the communication system 100 may include a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6. Also, the communication system 100 may further include a core network (e.g., S-GW (serving-gateway), P-GW (PDN (packet data network)-gateway), MME (mobility management entity)). When the communication system 100 is a 5G communication system (e.g., an NR (new radio) system), the core network may include an AMF (access and mobility management function), a UPF (user plane function), an SMF (session management function), etc.

[0040] The plurality of communication nodes 110 to 130 can support communication protocols defined by the 3GPP (registered trademark: 3rd generation partnership project) standard (for example, LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.). The plurality of communication nodes 110 to 130 can support CDMA (code division multiple access) technology, WCDMA (registered trademark: wideband CDMA) technology, TDMA (time division multiple access) technology, FDMA (frequency division multiple access) technology, OFDM (orthogonal frequency division multiplexing) technology, Filtered OFDM technology, CP (cyclic prefix)-OFDM technology, DFT-s-OFDM (discrete Fourier transform-spread-OFDM) technology, OFDMA (orthogonal frequency division multiple access) technology, SC (single carrier)-FDMA technology, NOMA (Non-orthogonal Multiple Access) technology, GFDM (generalized frequency division multiplexing) technology, FBMC (filter bank multi-carrier) technology, UFMC (universal filtered multi-carrier) technology, SDMA (Space Division Multiple Access) technology, etc. Each of the plurality of communication nodes can have the following structure.

[0041] FIG. 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system.

[0042] Referring to FIG. 2, the communication node 200 can include at least one processor 210, a memory 220, and a transceiver 230 connected to a network to perform communication. Further, the communication node 200 can further include an input interface device 240, an output interface device 250, a storage device 260, etc. Each component included in the communication node 200 can be connected by a bus 270 to perform communication.

[0043] However, each component included in the communication node 200 may be connected through an individual interface or an individual bus centered on the processor 210, rather than through the common bus 270. For example, the processor 210 may be connected to at least one of the memory 220, the transceiver 230, the input interface device 240, the output interface device 250, and the storage device 260 through a dedicated interface.

[0044] The processor 210 can execute program commands stored in at least one of the memory 220 and the storage device 260. The processor 210 can mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor for performing the method according to the embodiments of the present disclosure. Each of the memory 220 and the storage device 260 can be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 can be composed of at least one of a read only memory (ROM) and a random access memory (RAM).

[0045] Referring again to FIG. 1, the communication system 100 can include a plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2, and a plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 can form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 can form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 can belong within the cell coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 can belong within the cell coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 can belong within the cell coverage of the third base station 110-3. The first terminal 130-1 can belong within the cell coverage of the fourth base station 120-1. The sixth terminal 130-6 can belong within the cell coverage of the fifth base station 120-2.

[0046] Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2 can be referred to as an NB (NodeB), eNB (evolved NodeB), gNB, ABS (advanced base station), HR-BS (high reliability-base station), BTS (base transceiver station), radio base station, radio transceiver, access point, access node, RAS (radio access station), MMR-BS (mobile multihop relay-base station), RS (relay station), ARS (advanced relay station), HR-RS (high reliability-relay station), HNB (home NodeB), HeNB (home eNodeB), RSU (road side unit), RRH (radio remote head), TP (transmission point), TRP (transmission and reception point), etc.

[0047] Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 can be referred to as a UE (user equipment), TE (terminal equipment), AMS (advanced mobile station), HR-MS (high reliability-mobile station), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, OBU (on board unit), etc.

[0048] On the one hand, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2 can operate in different frequency bands from each other or can operate in the same frequency band. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2 can be connected through an ideal backhaul link or a non-ideal backhaul link and can exchange information through the ideal backhaul link or the non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2 can be connected to the core network through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2 can transmit the signals received from the core network to the corresponding terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6, and can transmit the signals received from the corresponding terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 to the core network.

[0049] In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2 can support MIMO transmission (e.g., SU (single user)-MIMO, MU (multi user)-MIMO, massive MIMO, etc.), CoMP (coordinated multipoint) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, device-to-device communication (D2D) (or ProSe (proximity services)), IoT (Internet of Things) communication, dual connectivity (DC), etc. Here, each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 can perform operations corresponding to the base stations 110-1, 110-2, 110-3, 120-1, 120-2 and operations supported by the base stations 110-1, 110-2, 110-3, 120-1, 120-2. For example, the second base station 110-2 can transmit a signal to the fourth terminal 130-4 based on the SU-MIMO method, and the fourth terminal 130-4 can receive the signal from the second base station 110-2 by the SU-MIMO method. Or the second base station 110-2 can transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 based on the MU-MIMO method, and each of the fourth terminal 130-4 and the fifth terminal 130-5 can receive the signal from the second base station 110-2 by the MU-MIMO method.

[0050] The first base station 110-1, the second base station 110-2, and the third base station 110-3 can each transmit signals to the fourth terminal 130-4 based on the CoMP method, and the fourth terminal 130-4 can receive signals from the first base station 110-1, the second base station 110-2, and the third base station 110-3 by the CoMP method. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2 can transmit and receive signals to and from the terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 belonging to its own cell coverage area based on the CA method. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 can control D2D between the fourth terminal 130-4 and the fifth terminal 130-5, and each of the fourth terminal 130-4 and the fifth terminal 130-5 can perform D2D under the control of the second base station 110-2 and the third base station 110-3, respectively.

[0051] On the other hand, the communication system can support three types of frame structures. The type 1 frame structure can be applied to an FDD (frequency division duplex) communication system, the type 2 frame structure can be applied to a TDD (time division duplex) communication system, and the type 3 frame structure can be applied to a communication system based on an unlicensed band (for example, an LAA (licensed assisted access) communication system).

[0052] FIG. 3 is a conceptual diagram illustrating a first embodiment of the type 1 frame structure.

[0053] Referring to FIG. 3, the radio frame 300 can include 10 subframes, and a subframe can include 2 slots. Therefore, the radio frame 300 can include 20 slots (for example, slot #0, slot #1, slot #2, slot #3,..., slot #18, slot #19). The length T of the radio frame 300 f is 10 ms (millisecond), the length of the subframe can be 1 ms, and the slot length Tslot can be 0.5 ms. Here, T s represents the sampling time and can be 1 / 30,720,000 s (second).

[0054] A slot can be composed of a plurality of OFDM symbols in the time domain and can be composed of a plurality of resource blocks (RBs) in the frequency domain. A resource block can be composed of a plurality of subcarriers in the frequency domain. The number of OFDM symbols constituting a slot can vary depending on the configuration of the cyclic prefix (CP). The CP can be classified into normal CP and extended CP. When normal CP is used, a slot can be composed of 7 OFDM symbols, and in this case, a subframe can be composed of 14 OFDM symbols. When extended CP is used, a slot can be composed of 6 OFDM symbols, and in this case, a subframe can be composed of 12 OFDM symbols.

[0055] FIG. 4 is a conceptual diagram illustrating a first embodiment of a type 2 frame structure.

[0056] Referring to FIG. 4, a radio frame 400 can include two half frames, and a half frame can include 5 subframes. Therefore, a radio frame 400 can include 10 subframes. The length T f of the radio frame 400 can be 10 ms. The length of a half frame can be 5 ms. The length of a subframe can be 1 ms. Here, T s can be 1 / 30,720,000 s.

[0057] The radio frame 400 can include a downlink subframe, an uplink subframe, and a special subframe. Each of the downlink subframe and the uplink subframe can include 2 slots. The slot length T slotIt can be 0.5 ms. Among the subframes included in radio frame 400, subframe #1 and subframe #6 can each be special subframes. For example, when the downlink - uplink switching period is 5 ms, radio frame 400 can include two special subframes. Or when the downlink - uplink switching period is 10 ms, radio frame 400 can include one special subframe. The special subframe can include a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS).

[0058] The downlink pilot time slot can be regarded as a downlink section and can be used for cell search of the terminal, acquisition of time and frequency synchronization, channel estimation, etc. The guard period can be used to solve the interference problem of uplink data transmission caused by downlink data reception delay. Also, the guard period can include the time required to convert from the downlink data reception operation to the uplink data transmission operation. The uplink pilot time slot can be used for uplink channel estimation, acquisition of time and frequency synchronization, etc. Transmission of a physical random access channel (PRACH) or a sounding reference signal (SRS) can be performed in the uplink pilot time slot.

[0059] The lengths of the downlink pilot time slot, the guard period, and the uplink pilot time slot included in the special subframe can each be variably adjusted as required. Also, the number and positions of the downlink subframes, uplink subframes, and special subframes included in radio frame 400 can be changed as required.

[0060] In a communication system, a TTI (transmission time interval) can be a basic time unit for transmitting encoded data through the physical layer. A short TTI can be used to support low-latency requirements in the communication system. The length of the short TTI may be less than 1 ms. The existing TTI having a length of 1 ms can be referred to as a base TTI or a regular TTI. In other words, the base TTI can be composed of one subframe. To support the transmission in units of the base TTI, signals and channels can be set in units of subframes. For example, CRS (cell-specific reference signal), PDCCH (physical downlink control channel), PDSCH (physical downlink shared channel), PUCCH (physical uplink control channel), PUSCH (physical uplink shared channel), etc. can exist for each subframe.

[0061] On the contrary, synchronization signals (e.g., PSS (primary synchronization signal), SSS (secondary synchronization signal)) can exist for every 5 subframes, and PBCH (physical broadcast channel) can exist for every 10 subframes. And a radio frame can be distinguished by SFN, and SFN can be used to define the transmission of signals whose transmission period is longer than one radio frame (e.g., paging signal, reference signal for channel estimation, signal indicating channel state information, etc.). The period of SFN can be 1024.

[0062] In the LTE system, the PBCH can be a physical layer channel used for the transmission of system information (e.g., MIB (master information block)). The PBCH can be transmitted every 10 subframes. In other words, the transmission period of the PBCH can be 10 ms, and the PBCH can be transmitted once in a radio frame. The same MIB can be transmitted among 4 consecutive radio frames, and after 4 consecutive radio frames, the MIB can be changed according to the situation of the LTE system. The transmission period of the same MIB can be referred to as "PBCH TTI", and the PBCH TTI can be 40 ms. In other words, the MIB can be changed every PBCH TTI.

[0063] The MIB can be composed of 40 bits. Among the 40 bits that make up the MIB, 3 bits can be used to indicate the system bandwidth, 3 bits can be used to indicate PHICH (physical hybrid ARQ (automatic repeat request) indicator channel) related information, 8 bits can be used to indicate the SFN, 10 bits can be set as reserved bits, and 16 bits can be used for CRC (cyclic redundancy check).

[0064] The SFN that divides the radio frame can be composed of a total of 10 bits (B9~B0). Among the 10 bits, the 8 MSB (most significant bit) bits (B9~B2) can be indicated by the PBCH (for example, MIB). The 8 MSB bits (B9~B2) of the SFN indicated by the PBCH (for example, MIB) can be the same among 4 consecutive radio frames (for example, PBCH TTI). The 2 LSB (least significant bit) bits (B1~B0) of the SFN can be changed among 4 consecutive radio frames (for example, PBCH TTI) and may not be explicitly indicated by the PBCH (for example, MIB). The 2 LSB bits (B1~B0) of the SFN can be implicitly indicated by the scrambling sequence for the PBCH (hereinafter referred to as the "PBCH scrambling sequence").

[0065] A gold sequence generated by initializing with the cell ID can be used as the PBCH scrambling sequence, and the PBCH scrambling sequence can be initialized for every 4 consecutive radio frames (for example, PBCH TTI) by mod(SFN, 4). The PBCH transmitted in the radio frame corresponding to the SFN with the 2 LSB bits (B1~B0) set to "00" can be scrambled by the gold sequence generated by initializing with the cell ID. Thereafter, the gold sequence generated by mod(SFN, 4) can be used to scramble the PBCH transmitted in the radio frames where the 2 LSB bits (B1~B0) of the SFN are "01", "10", and "11".

[0066] Therefore, a terminal that has obtained a cell ID during the initial cell search process can implicitly find out the values (e.g., "00", "01", "10", "11") of the least significant 2 bits (B1~B0) of the SFN through the PBCH scrambling sequence during the PBCH (e.g., MIB) decoding process. The terminal can confirm the SFN (e.g., the entire bits of the SFN (B9~B0)) using the least significant 2 bits (B1~B0) of the SFN confirmed based on the PBCH scrambling sequence and the most significant 8 bits (B9~B2) of the SFN indicated by the PBCH (e.g., MIB).

[0067] On the other hand, the communication system can support technical requirements for not only high transmission speeds but also various service scenarios. For example, the communication system can support high transmission speeds (enhanced Mobile BroadBand; eMBB), short transmission delay times (Ultra Reliable Low Latency Communication; URLLC), massive terminal connectivity (massive Machine Type Communication; mMTC), etc.

[0068] The subcarrier spacing of a communication system (e.g., an OFDM-based communication system) can be determined based on the CFO (carrier frequency offset), etc. The CFO can be generated by the Doppler effect, phase drift, etc., and can increase in proportion to the operating frequency. Therefore, in order to prevent the performance degradation of the communication system due to the CFO, the subcarrier spacing can increase in proportion to the operating frequency. On the contrary, as the subcarrier spacing increases, the CP overhead can increase. Therefore, the subcarrier spacing can be set based on channel characteristics, RF (radio frequency) characteristics, etc. due to the frequency band.

[0069] The communication system can support the numerology defined in Table 1 below.

Table 1

[0070] For example, the subcarrier spacing of a communication system can be set to 15 kHz, 30 kHz, 60 kHz, or 120 kHz. The subcarrier spacing of an LTE system can be 15 kHz, and in an NR system, the subcarrier spacing can be 1, 2, 4, or 8 times the existing subcarrier spacing of 15 kHz. When the subcarrier spacing increases in units of an exponential multiple of 2 of the existing subcarrier spacing, the frame structure can be easily designed.

[0071] The communication system can support not only FR1 but also FR2. FR2 can be classified into FR2-1 and FR2-2. FR1 can be a frequency band of 6 GHz or less, FR2-1 can be a band of 24.25 - 52.6 GHz, and FR2-2 can be a band of 52.6 - 71 GHz. In an embodiment, FR2 can be a frequency band including FR2-1, FR2-2, or both FR2-1 and FR2-2. The subcarrier spacing available for data transmission in FR1, FR2-1, and FR2-2 respectively can be defined as shown in Table 2 below. The subcarrier spacing available for SSB (synchronization signal block) transmission in FR1, FR2-1, and FR2-2 respectively can be defined as shown in Table 3 below. The subcarrier spacing available for RACH (random access channel) transmission (e.g., Msg1 or Msg-A) in FR1, FR2-1, and FR2-2 respectively can be defined as shown in Table 4 below.

Table 2

Table 3

Table 4

[0072] The communication system can support a wide frequency band (e.g., several hundred MHz to several tens of GHz). Since the diffraction characteristics and reflection characteristics of radio waves are not good in a high frequency band, the propagation loss (e.g., path loss, reflection loss, etc.) in a high frequency band may be larger than that in a low frequency band. Therefore, the cell coverage of a communication system supporting a high frequency band may be smaller than that of a communication system supporting a low frequency band. To solve such a problem, in order to increase the cell coverage in a communication system supporting a high frequency band, a beamforming method based on a plurality of antenna elements can be used.

[0073] The beamforming method can include a digital beamforming method, an analog beamforming method, a hybrid beamforming method, etc. In a communication system using the digital beamforming method, beamforming gain can be obtained using a plurality of RF paths based on a digital precoder or a codebook. In a communication system using the analog beamforming method, beamforming gain can be obtained through an analog RF device (e.g., a phase shifter, a PA (power amplifier), a VGA (variable gain amplifier), etc.) and an antenna array.

[0074] For a digital beamforming system, a high - performance DAC (digital - to - analog converter) or ADC (analog - to - digital converter) and a transceiver unit corresponding to the number of antenna elements are required. Therefore, the complexity of implementing the antenna may increase to increase the beamforming gain. In a communication system using the analog beamforming method, since multiple antenna elements are connected to a single transceiver unit through phase shifters, the complexity of implementing the antenna may not increase significantly even when increasing the beamforming gain. However, the beamforming performance of a communication system using the analog beamforming method may be lower than that of a communication system using the digital beamforming method. Also, in a communication system using the analog beamforming method, since the phase shifter is adjusted in the time domain, the frequency resources may not be used efficiently. Therefore, a hybrid beamforming method, which is a combination of the digital and analog methods, can be used.

[0075] When cell coverage increases due to the use of the beamforming method, not only the control channels and data channels of each terminal but also the common control channels and common signals (e.g., reference signals, synchronization signals) for all terminals belonging to the cell coverage can be transmitted based on the beamforming method. In this case, the common control channels and common signals for all terminals belonging to the cell coverage can be transmitted based on the beam - sweeping method.

[0076] Also, in the NR system, the SS / PBCH (synchronization block / physical broadcast channel) block can also be transmitted in a beam sweeping manner. The SS / PBCH block can be composed of PSS, SSS, PBCH, etc., and PSS, SSS, and PBCH can be configured in a TDM (time division multiplexing) manner within the SS / PBCH block. In an embodiment, the SS / PBCH block can be referred to as an SSB. One SS / PBCH block can be transmitted using N consecutive OFDM symbols. Here, N can be an integer greater than or equal to 4. The base station can transmit the SS / PBCH block periodically, and the terminal can acquire frequency / time synchronization, cell ID, system information, etc. based on the SS / PBCH block received from the base station. The SS / PBCH block can be transmitted as follows.

[0077] FIG. 5 is a conceptual diagram illustrating a first embodiment of a method for transmitting an SS / PBCH block in a communication system.

[0078] Referring to FIG. 5, one or more SS / PBCH blocks can be transmitted in a beam sweeping manner within an SS / PBCH block burst set. A maximum of L SS / PBCH blocks can be transmitted within one SS / PBCH block burst set. L can be an integer greater than or equal to 2 and can be defined by the 3GPP standard. L can vary depending on the system frequency region. The SS / PBCH blocks within the SS / PBCH block burst set can be located continuously or dispersedly. Consecutive SS / PBCH blocks can be referred to as an "SS / PBCH block burst" or an "SSB burst". The SS / PBCH block burst set can be repeated periodically, and the system information (e.g., MIB) transmitted through the PBCH of the SS / PBCH blocks within the SS / PBCH block burst set can be the same. The SS / PBCH block index, SS / PBCH block burst index, OFDM symbol index, slot index, etc. can be explicitly or implicitly indicated by the PBCH.

[0079] FIG. 6 is a conceptual diagram illustrating a first embodiment of an SS / PBCH block in a communication system.

[0080] Referring to FIG. 6, the arrangement order within the SS / PBCH block can be "PSS → PBCH → SSS → PBCH". PSS, SSS, and PBCH within the SS / PBCH block can be configured in a TDM manner. PBCH can be arranged in frequency resources higher than SSS and lower than SSS in the symbol where SSS is located. When the maximum number of SS / PBCH blocks in a frequency band of 6 GHz or less is 8, the index of the SS / PBCH block can be confirmed based on a DMRS (demodulation reference signal) (hereinafter referred to as "PBCH DMRS") used for demodulation of PBCH. When the maximum number of SS / PBCH blocks in a frequency band of 6 GHz or more is 64, among the 6 bits indicating the index of the SS / PBCH block, the LSB 3 bits can be confirmed based on PBCH DMRS, and the remaining MSB 3 bits can be confirmed based on the PBCH payload.

[0081] The maximum system bandwidth supportable in the NR system can be 400 MHz. The magnitude of the maximum bandwidth supportable by a terminal can vary depending on the capability of the terminal. Therefore, the terminal can perform an initial connection procedure (e.g., an initial association procedure) using a part of the system bandwidth within the system bandwidth of the NR system that supports a wide bandwidth. To support the connection procedures of terminals supporting bandwidths of various magnitudes, the SS / PBCH blocks can be multiplexed in the frequency axis within the system bandwidth of the NR system that supports a wide bandwidth. In this case, the SS / PBCH blocks can be transmitted as follows.

[0082] FIG. 7 is a conceptual diagram illustrating a second embodiment of a transmission method of an SS / PBCH block in a communication system.

[0083] Referring to FIG. 7, a wideband component carrier (CC) can include a plurality of bandwidth parts (BWPs). For example, a wideband CC can include four BWPs. The base station can transmit SS / PBCH blocks in each of BWPs #0 to 3 belonging to the wideband CC. The terminal can receive SS / PBCH blocks in one or more of BWPs #0 to 3 and use the received SS / PBCH blocks to perform the initial connection procedure.

[0084] After detecting the SS / PBCH block, the terminal can obtain system information (e.g., RMSI (remaining minimum system information)) and perform the cell connection procedure based on the system information. The RMSI can be transmitted through the PDSCH scheduled by the PDCCH. The configuration information of the CORESET (control resource set) through which the PDCCH including the scheduling information of the PDSCH for transmitting the RMSI is transmitted can be transmitted through the PBCH in the SS / PBCH block. A plurality of SS / PBCH blocks can be transmitted in the entire system bandwidth, and one or more of the plurality of SS / PBCH blocks can be SS / PBCH blocks related to the RMSI. The remaining SS / PBCH blocks may not be related to the RMSI. The SS / PBCH block related to the RMSI can be defined as the "cell defining SS / PBCH block". The terminal can use the cell defining SS / PBCH block to perform the cell search procedure and the initial connection procedure. The SS / PBCH block not related to the RMSI can be used for the synchronization procedure and / or the measurement procedure in the corresponding BWP. The BWP in which the SS / PBCH block is transmitted can be limited to one or more BWPs within a wide bandwidth.

[0085] The position where SSB is transmitted in the time domain can be defined differently according to SCS (subcarrier spacing) and the L value. In an embodiment, SCS may mean the size of a subcarrier. SSB can be transmitted in some symbols within one slot, and short UL transmission (e.g., UCI (Uplink control information) transmission) can be performed in the remaining symbols not used for SSB transmission within one slot. When SSB is transmitted in a radio resource to which a large SCS (e.g., 120 kHz SCS or 240 kHz SCS) is applied, a gap can be set in the middle of consecutive slots including SSB so that long UL transmission (e.g., transmission of URLLC traffic) is possible at least every 1 ms.

[0086] FIG. 8 is a conceptual diagram illustrating a first embodiment of an SSB burst configuration.

[0087] Referring to FIG. 8, in a procedure for transmitting SSB (e.g., an SSB burst) in a radio resource to which 120 kHz SCS is applied, the base station can transmit SSB in 8 consecutive slots. In a procedure for transmitting SSB in a radio resource to which 240 kHz SCS is applied, the base station can transmit SSB in 16 consecutive slots. A gap for UL transmission can be set in a radio resource to which 120 kHz SCS or 240 kHz SCS is applied.

[0088] RMSI can be obtained by performing "operation of obtaining configuration information of CORESET from an SS / PBCH block (e.g., PBCH) → operation of detecting PDCCH based on the configuration information of CORESET → operation of obtaining scheduling information of PDSCH from PDCCH → operation of receiving RMSI through PDSCH". The transmission resource of PDCCH can be set according to the configuration information of CORESET. The RMSI CORESET mapping pattern can be defined as follows. RMSI CORESET can be a CORESET used for transmission and reception of RMSI.

[0089] FIG. 9a is a conceptual diagram illustrating RMSI CORESET mapping pattern #1 in a communication system, FIG. 9b is a conceptual diagram illustrating RMSI CORESET mapping pattern #2 in a communication system, and FIG. 9c is a conceptual diagram illustrating RMSI CORESET mapping pattern #3 in a communication system.

[0090] Referring to FIGS. 9a to 9c, one of the RMSI CORESET mapping patterns #1-3 can be used, and the detailed settings according to one RMSI CORESET mapping pattern can be completed. In RMSI CORESET mapping pattern #1, the SS / PBCH block, CORESET (e.g., RMSI CORESET), and PDSCH (e.g., RMSI PDSCH) can be set in a TDM manner. The RMSI PDSCH can mean the PDSCH on which RMSI is transmitted. In RMSI CORESET mapping pattern #2, the CORESET (e.g., RMSI CORESET) and PDSCH (e.g., RMSI PDSCH) can be set in a TDM manner, and the PDSCH (e.g., RMSI PDSCH) can be set with the SS / PBCH block in an FDM (frequency division multiplexing) manner. In RMSI CORESET mapping pattern #3, the CORESET (e.g., RMSI CORESET) and PDSCH (e.g., RMSI PDSCH) can be set in a TDM manner, and the CORESET (e.g., RMSI CORESET) and PDSCH (e.g., RMSI PDSCH) can be set with the SS / PBCH block in an FDM manner.

[0091] Only RMSI CORESET mapping pattern #1 can be used in the frequency band below 6 GHz. In the frequency band above 6 GHz, all of RMSI CORESET mapping patterns #1, #2, and #3 can be used. The numerology of the SS / PBCH block may be different from the numerology of "RMSI CORESET and RMSI PDSCH". Here, the numerology can be the subcarrier spacing. All combinations of numerologies can be used in RMSI CORESET mapping pattern #1. In RMSI CORESET mapping pattern #2, the combination of "SS / PBCH block, RMSI CORESET / PDSCH = 120 kHz, 60 kHz or 240 kHz, 120 kHz" can be used. In RMSI CORESET mapping pattern #3, the combination of "SS / PBCH block, RMSI CORESET / PDSCH = 120 kHz, 120 kHz" can be used.

[0092] Based on the combination of the numerology of the SS / PBCH block and the numerology of the RMSI CORESET / PDSCH, one of the RMSI CORESET mapping patterns #1 - 3 can be selected. The configuration information of the RMSI CORESET can include Table A and Table B. Table A can indicate the number of resource blocks (RBs) of the RMSI CORESET, the number of symbols of the RMSI CORESET, and the offset between the RB of the SS / PBCH block (e.g., the starting RB or the ending RB) and the RB of the RMSI CORESET (e.g., the starting RB or the ending RB). Table B can indicate the number of search space sets per slot, the offset of the RMSI CORESET, and the OFDM symbol index for each RMSI CORESET mapping pattern. Table B can indicate the information for the setting of the monitoring occasion of the RMSI PDCCH. Each of Table A and Table B can be composed of multiple tables. For example, Table A can include Tables 13 - 1 to 13 - 8 defined in TS 38.213, and Table B can include Tables 13 - 9 to 13 - 13 defined in TS 38.213. The size of each of Table A and Table B can be 4 bits.

[0093] In the NR system, the PDSCH can be mapped in the time domain according to the PDSCH mapping type A or B. The PDSCH mapping types A and B can be defined as shown in Table 5 below.

Table 5

[0094] Type A (e.g., PDSCH mapping type A) can be slot-based transmission. When Type A is used, the position of the start symbol of PDSCH can be set to one of {0, 1, 2, 3}. When Type A and normal CP are used, the number of symbols constituting PDSCH (e.g., the duration of PDSCH) can be set to one value among 3 to 14 within the symbol boundary. Type B (e.g., PDSCH mapping type B) can be non-slot-based transmission. When Type B is used, the position of the start symbol of PDSCH can be set to one of 0 to 12. When Type B and normal CP are used, the number of symbols constituting PDSCH (e.g., the duration of PDSCH) can be set to one value among {2, 4, 7} within the symbol boundary. The DMRS (hereinafter referred to as "PDSCH DMRS") for demodulation of PDSCH (e.g., data) can be determined based on the PDSCH mapping type (e.g., Type A, Type B) and the ID indicating the length. The ID can be defined differently depending on the PDSCH mapping type.

[0095] On the other hand, NR-U (unlicensed) is being discussed in the NR standardization meeting. The NR-U system can increase network capacity by improving the utilization of limited frequency resources. The NR-U system can support operation in an unlicensed band (e.g., unlicensed spectrum).

[0096] In the NR-U system, a terminal can determine whether there is signal transmission at the corresponding base station based on the DRS (Discovery Reference Signal) received from the base station in the same way as in a general NR system. In the SA (Stand-Alone) mode NR-U system, a terminal can acquire synchronization and / or system information based on the DRS. In the NR-U system, the DRS can be transmitted according to the regulations of the unlicensed band (for example, transmission band, transmission power, transmission time, etc.). For example, according to the OCB (Occupied Channel Bandwidth) regulation, the signal can be configured and / or transmitted so as to occupy 80% of the entire channel bandwidth (for example, 20 MHz).

[0097] In the NR-U system, a communication node (for example, a base station, a terminal) can perform LBT (Listen Before Talk) before transmitting a signal and / or a channel for coexistence with other systems. The signal can be a synchronization signal, a reference signal (for example, DRS, DMRS, CSI (channel state information)-RS, PT (phase tracking)-RS, SRS (sounding reference signal)), etc. The channel can be a downlink channel, an uplink channel, a sidelink channel, etc. In an embodiment, the signal can mean "signal", "channel", or "signal and channel". LBT can be an operation for checking whether a signal is transmitted by other communication nodes. If it is determined by LBT that there is no transmission signal (for example, when LBT is successful), the communication node can transmit a signal in the unlicensed band. If it is determined by LBT that there is a transmission signal (for example, when LBT fails), the communication node may not be able to transmit a signal in the unlicensed band. The communication node can perform LBT according to various categories before transmitting a signal. The category of LBT can vary depending on the type of the transmission signal.

[0098] On the one hand, NR V2X (vehicular to everything) communication technology is being discussed at the NR standardization meeting. The NR V2X communication technology can be a technology that supports communication between vehicles, communication between a vehicle and infrastructure, communication between a vehicle and a pedestrian, etc. based on D2D (device to device) communication technology. Technologies for reducing power consumption and improving reliability for NR V2X communication are being discussed.

[0099] NR V2X communication (e.g., sidelink communication) can be performed by three transmission methods (e.g., unicast method, broadcast method, groupcast method). When the unicast method is used, a PC5-RRC connection can be established between a first terminal (e.g., a transmitting terminal that transmits data) and a second terminal (e.g., a receiving terminal that receives data), and the PC5-RRC connection can mean a logical connection for a pair between the source ID of the first terminal and the destination ID of the second terminal. The first terminal can transmit data (e.g., sidelink data) to the second terminal. When the broadcast method is used, the first terminal can transmit data to all terminals. When the groupcast method is used, the first terminal can transmit data to a group (e.g., a groupcast group) composed of a plurality of terminals. In SL communication (e.g., SL-U communication), the transmitting terminal can mean a terminal that transmits data, and the receiving terminal can mean a terminal that receives data.

[0100] When the unicast mode is used, the second terminal can transmit feedback information (e.g., ACK (acknowledgement) or NACK (negative ACK)) for the data received from the first terminal to the first terminal. In the following embodiments, the feedback information may be referred to as "HARQ-ACK", "feedback signal", "PSFCH (physical sidelink feedback channel) signal", etc. When an ACK is received from the second terminal, the first terminal can determine that the data has been successfully received at the second terminal. When a NACK is received from the second terminal, the first terminal can determine that the second terminal has failed to receive the data. In this case, the first terminal can transmit additional information to the second terminal based on the HARQ (hybrid automatic repeat request) mode. Or the first terminal can improve the probability of data reception at the second terminal by retransmitting the same data to the second terminal.

[0101] When the broadcast mode is used, the procedure for transmitting feedback information for the data may not be performed. For example, system information may be transmitted in the broadcast mode, and the terminal may not be able to transmit feedback information for the system information to the base station. Therefore, the base station may not know whether the system information has been successfully received at the terminal. To solve such a problem, the base station can broadcast the system information periodically.

[0102] When the group cast method is used, the transmission procedure of feedback information for data may not be performed. For example, information that does not require the transmission procedure of feedback information can be periodically transmitted by the group cast method. However, when the target and / or the number of terminals participating in communication based on the group cast method are limited, and the data transmitted by the group cast method is data that must be received within a preset time (for example, data sensitive to delay), the transmission procedure of feedback information may also be required in group cast sidelink communication. Group cast sidelink communication can mean sidelink communication performed by the group cast method. When the transmission procedure of feedback information is performed in group cast sidelink communication, data can be transmitted and received efficiently and stably.

[0103] Two HARQ-ACK feedback methods (for example, the transmission procedure of feedback information) can be supported in group cast sidelink communication. "When there are many receiving terminals in the sidelink group and service scenario 1 is supported", some receiving terminals belonging to a specific range in the sidelink group can transmit NACK through PSFCH when the data reception fails. This method can be "group cast HARQ-ACK feedback option 1". In service scenario 1, it may be allowed for some receiving terminals belonging to a specific range to receive in a best-effort manner instead of all receiving terminals in the sidelink group. Service scenario 1 can be an extended sensor scenario where some receiving terminals belonging to a specific range need to receive the same sensor information from the transmitting terminal. In an embodiment, the transmitting terminal can mean the terminal that transmits data, and the receiving terminal can mean the terminal that receives data.

[0104] When "the number of receiving terminals within the sidelink group is restrictive and Service Scenario 2 is supported", each of all the receiving terminals belonging to the sidelink group can individually report HARQ-ACK for data through a separate PSFCH. This method can be "Groupcast HARQ-ACK Feedback Option 2". Since there are sufficient PSFCH resources in Service Scenario 2, the transmitting terminal can perform monitoring of HARQ-ACK feedback for all the receiving terminals belonging to the sidelink group, and the reception of data can be guaranteed for all the receiving terminals belonging to the sidelink group.

[0105] Similar to broadcast sidelink communication, data can be transmitted and received without a HARQ-ACK feedback procedure in unicast sidelink communication and groupcast sidelink communication. In this case, in order to increase the reception probability of data, the transmitting terminal can retransmit the data a preset number of times.

[0106] For all transmission modes (e.g., unicast transmission, groupcast transmission, broadcast transmission), whether the HARQ-ACK feedback procedure is applied can be fixedly or semi-statically set for the terminal through signaling (e.g., system information signaling, PC5-RRC signaling, UE-specific RRC signaling, control information signaling). In sidelink communication, HARQ-ACK feedback information can be transmitted on the PSFCH. When the PSSCH reception is successful, the receiving terminal can transmit an ACK for the PSSCH (e.g., data) on the PSFCH. When the PSSCH reception fails, the receiving terminal can transmit a NACK for the PSSCH (e.g., data) on the PSFCH. The PSFCH can be a channel for reporting ACK / NACK information (e.g., HARQ-ACK feedback) to the transmitting terminal. A resource region (e.g., PSFCH resource region) for PSFCH transmission (e.g., HARQ-ACK feedback transmission) within a specific resource pool can be preset. The PSFCH (e.g., PSFCH resource, PSFH resource region) can be set periodically. The PSFCH period for the PSFCH resource can be k slots (e.g., logical SL (sidelink) slots). k can be a natural number. For example, k can be 1, 2, or 4.

[0107] FIG. 10 is a conceptual diagram illustrating a first embodiment of a slot configuration in which the PSFCH is set.

[0108] Referring to FIG. 10, within a slot (e.g., SL slot), the PSFCH (e.g., HARQ-ACK feedback) can be repeatedly transmitted in two symbols (e.g., two OFDM symbols). The first of the two symbols in which the PSFCH is transmitted can be used for AGC (automatic gain control) purposes for correct PSFCH reception power level adjustment.

[0109] The PSFCH can be transmitted within a frequency resource region preset according to system information. In this case, the frequency resource region for PSFCH transmission can be indicated (e.g., by signaling) in the form of a bitmap within a resource pool. The receiving terminal can implicitly select the position of the frequency resource region for PSFCH transmission based on the slot and subchannel index where the PSSCH is received. The receiving terminal can confirm the number of multiplexable PSFCH resources based on the resource block (RB) and cyclic shift of the PSFCH sequence within the frequency resource region. The receiving terminal can implicitly select the PSFCH index for the PSFCH resource based on the source ID (identifier) and member ID. The source ID can be a physical layer source ID. The source ID can be the ID of the transmitting terminal that transmitted the PSSCH.

[0110] The member ID can be used in groupcast HARQ-ACK feedback option 2. When groupcast HARQ-ACK feedback option 2 is applied, each receiving terminal within the group can individually transmit the HARQ-ACK feedback for the SL data through a separate PSFCH (e.g., PSFCH resource). If it is different from the above embodiment, the member ID can be set to 0.

[0111] FIG. 11 is a conceptual diagram illustrating a first embodiment of the PSFCH for ACK / NACK transmission.

[0112] Referring to FIG. 11, the transmission time of the PSFCH can be the first slot (e.g., the PSFCH slot) in which PSFCH transmission is possible after a preset time (e.g., sl-MinTimeGapPSFCH) from the reception time of the PSSCH. The PSFCH slot can be a slot in which PSFCH transmission is possible and / or a slot in which the PSFCH is configured. sl-MinTimeGapPSFCH can be set considering "the time for processing the PSSCH after receiving the PSSCH" and "the time for preparing ACK / NACK (e.g., HARQ-ACK feedback) depending on the success or failure of receiving the PSSCH". sl-MinTimeGapPSFCH can be set to 2 or 3 slots. The terminal (e.g., the receiving terminal) can transmit the PSFCH in slot #n+12, which is a slot in which PSFCH transmission is possible after sl-MinTimeGapPSFCH (e.g., 3 slots) from the reception time of the PSSCH. n can be an integer greater than or equal to 0. In the present disclosure, the reception time can mean the reception start time and / or the reception end time, and the transmission time can mean the transmission start time and / or the transmission end time. The time point can mean time and / or duration.

[0113] In the receiving terminal, the data reliability can be improved by appropriately adjusting the power of the transmitting terminal according to the transmission environment. The interference from other terminals can be mitigated by appropriately adjusting the power of the transmitting terminal. The energy efficiency can be improved by reducing unnecessary transmission power. The power control method can be classified into an open-loop power control method and a closed-loop power control method. In the open-loop power control method, the transmitting terminal can determine the transmission power considering the set and measured environment, etc. In the closed-loop power control method, the transmitting terminal can determine the transmission power based on the transmit power control (TPC) command received from the receiving terminal.

[0114] Predicting the strength of a received signal at a receiving terminal can be difficult due to various causes including multipath fading channels, interference, etc. Therefore, the receiving terminal can adjust the received power level (e.g., received power range) by performing an AGC (automatic gain control) operation to prevent quantization errors of the received signal and maintain appropriate received power. In a communication system, the terminal can perform the AGC operation using a reference signal received from a base station. However, in sidelink communication (e.g., V2X communication), the reference signal may not be transmitted from the base station. In other words, communication between terminals can be performed without a base station in sidelink communication. Therefore, it can be difficult to perform the AGC operation in sidelink communication. In sidelink communication, the transmitting terminal can transmit a signal (e.g., reference signal) to the receiving terminal before transmitting data, and the receiving terminal can adjust the received power range (e.g., received power level) by performing the AGC operation based on the signal received from the transmitting terminal. Thereafter, the transmitting terminal can transmit sidelink data to the receiving terminal. The signal used for the AGC operation can be a duplicated signal for a signal to be transmitted later or a signal preset between terminals.

[0115] The time interval required for the AGC operation can be 15 μs. When the subcarrier spacing is 15 kHz in the NR system, the time interval (e.g., length) of one symbol (e.g., OFDM symbol) can be 66.7 μs. When the subcarrier spacing is 30 kHz in the NR system, the time interval of one symbol can be 33.3 μs. In the following embodiments, the symbol can mean an OFDM symbol. In other words, the time interval of one symbol can be more than twice the time interval required for the AGC operation.

[0116] For sidelink communication, it may be necessary to transmit a control channel including a data channel for data transmission and scheduling information for data resource allocation. In sidelink communication, the data channel may be a PSSCH (Physical Sidelink Shared Channel), and the control channel may be a PSCCH (Physical Sidelink Control Channel). The data channel and the control channel may be multiplexed in a resource region (e.g., a time and frequency resource region).

[0117] FIG. 12 is a conceptual diagram illustrating an example of a method for multiplexing a control channel and a data channel in sidelink communication.

[0118] Referring to FIG. 12, sidelink communication can support Option 1A, Option 1B, Option 2, and Option 3. When Option 1A and / or Option 1B is supported, the control channel and the data channel can be multiplexed in the time domain. When Option 2 is supported, the control channel and the data channel can be multiplexed in the frequency domain. When Option 3 is supported, the control channel and the data channel can be multiplexed in the time and frequency domains. Sidelink communication can basically support Option 3.

[0119] In sidelink communication (e.g., NR-V2X sidelink communication), the basic unit of resource configuration may be a subchannel. The subchannel can be defined with time and frequency resources. For example, the subchannel can be composed of a plurality of symbols (e.g., OFDM symbols) in the time domain and can be composed of a plurality of RBs (resource blocks) in the frequency domain. The subchannel can be referred to as a set of RBs. Within the subchannel, the data channel and the control channel can be multiplexed based on Option 3.

[0120] In sidelink communication (e.g., NR-V2X sidelink communication), transmission resources can be allocated based on Mode 1 or Mode 2. When Mode 1 is used, the base station can allocate sidelink resources for data transmission within a resource pool to a transmitting terminal, and the transmitting terminal can use the sidelink resources allocated by the base station to transmit data to a receiving terminal. Here, the transmitting terminal can be a terminal that transmits data in sidelink communication, and the receiving terminal can be a terminal that receives data in sidelink communication.

[0121] When Mode 2 is used, the transmitting terminal can autonomously select sidelink resources for data transmission by performing a resource sensing operation (e.g., a resource sensing procedure) and / or a resource selection operation (e.g., a resource selection procedure) within the resource pool. The base station can configure for the terminal a resource pool for Mode 1 and a resource pool for Mode 2. The resource pool for Mode 1 can be configured independently of the resource pool for Mode 2. Or a common resource pool can be configured for both Mode 1 and Mode 2.

[0122] When Mode 1 is used, the base station can schedule the resources used for sidelink data transmission to a transmitting terminal, and the transmitting terminal can use the resources scheduled by the base station to transmit sidelink data to a receiving terminal. Thus, resource collisions between terminals can be prevented. When Mode 2 is used, the transmitting terminal can select any resource by performing a resource sensing operation and / or a resource selection operation, and can transmit sidelink data using any of the selected resources. Since the above-described procedure is performed based on the individual resource sensing operations and / or resource selection operations of each transmitting terminal, collisions between the selected resources can occur.

[0123] FIG. 13 is a conceptual diagram illustrating a first embodiment of a resource selection operation.

[0124] Referring to FIG. 13, a terminal (e.g., a transmitting terminal) can perform a resource sensing operation within a sensing window and can perform a resource selection operation on the resources (e.g., candidate resources) sensed within a selection window. When the resource selection operation is triggered by n, the terminal can select a suitable resource within the selection window (e.g., the interval from n + T1 to n + T2) based on the sensing result (e.g., the resources sensed by the resource sensing operation) within the sensing window (e.g., the interval from n - T0 to n - T proc、0 up to).

[0125] The terminal can exclude candidate resources that do not meet the conditions within the selection window based on the result of the resource sensing operation. In other words, the terminal can determine the remaining candidate resources excluding the candidate resources that are not suitable among all the candidate resources. If the ratio of the remaining candidate resources among all the resources within the selection window is less than the reference ratio, the terminal can relax the conditions for excluding candidate resources. For example, the terminal can increase the RSRP (reference signal received power) threshold, which is the condition for excluding candidate resources, by 3 dB. Then, the terminal can perform the resource selection operation again. The reference ratio can be preset to one of 20%, 35%, or 50% according to the priority. If the ratio of the remaining candidate resources is equal to or greater than the reference ratio, the terminal can randomly select the final resources for SL transmission from among the remaining candidate resources. The terminal can perform SL transmission using the final resources.

[0126] FIG. 14 is a conceptual diagram illustrating a first embodiment of a resource re-selection operation.

[0127] Referring to FIG. 14, the terminal can perform a resource re-selection operation in consideration of aperiodic data transmission and the like after the resource selection operation. The terminal can perform a resource re-selection operation by additionally considering the sensing result before the actual SL transmission (m-T3) after performing the operations illustrated in FIG. 13. The resource re-selection operation can be performed within a re-selection window. The terminal can additionally determine the suitability of the resources reserved by m. When it is determined that the resources reserved by m are suitable, the terminal can perform SL transmission using the reserved resources. When it is determined that the resources reserved by m are not suitable, the terminal can re-select resources for SL transmission and perform SL transmission using the re-selected resources.

[0128] When an independent SL carrier is not configured in SL communication, a part of the UL resources can be configured as SL resources by the SL resource pool configuration procedure. The bitmap can be repeatedly applied to the remaining slots excluding the slots in which at least X or more UL symbols are not configured within a specific period and the slots in which S (sidelink)-SSB is transmitted. X can be a natural number. The bitmap can indicate the slots used as SL resources. For example, the slots corresponding to the bits set to 1 among the bits in the bitmap can be used as SL resources.

[0129] It can be assumed that "when 15 kHz SCS (subcarrier spacing) is applied and X or more UL symbols are set in all slots". "When there are 10,240 available slots within the DFN (direct frame number), the transmission period of S-SSB is 160 ms, and there are 2 slots used for S-SSB transmission in each transmission period of S-SSB", the number of slots used for S-SSB transmission within the DFN can be 128. The bitmap for SL time resource setting can include 10 bits. When the bitmap (for example, a bitmap including 10 bits) is repeatedly applied to the remaining 10,112 slots out of the 10,240 slots excluding the 128 slots used for S-SSB transmission, there can be 2 slots (for example, reserved slots) to which the bitmap is not applied. It may be necessary to exclude the 2 reserved slots. After excluding the 2 reserved slots from the 10,112 slots, 10,110 slots can remain. The bitmap (for example, a bitmap including 10 bits) can be repeatedly applied 1,011 times to the 10,110 slots. "When the bitmap is 1111000000 and the slots corresponding to the bits set to 1 are used as SL resources", 4,044 slots can be set as SL resources within the DFN. In other words, 4,044 slots out of the 10,240 slots can be used for SL communication by setting the SL resource pool.

[0130] A sidelink communication system supporting Rel-16 can be designed for a terminal with no significant battery capacity constraint (e.g., a terminal mounted on an automobile, a V-UE (vehicle UE)). Therefore, power reduction issues may not need to be significantly considered in the resource sensing / selection operation of the terminal. For sidelink communication with a terminal having a battery capacity constraint (e.g., a terminal held by a pedestrian, a terminal mounted on a bicycle, a terminal mounted on a motorcycle, a P-UE (pedestrian UE)) in a sidelink communication system supporting Rel-17, a power reduction method will be necessary. In the present disclosure, V-UE may mean a terminal with no significant battery capacity constraint, P-UE may mean a terminal having a battery capacity constraint, and the "resource sensing / selection operation" can include the "resource sensing operation and / or the resource selection operation". The resource sensing operation may mean a partial sensing operation or a full sensing operation. The resource selection operation may mean a random selection operation. Also, in the present disclosure, the "operation of the terminal" can be interpreted as the "operation of the V-UE" and / or the "operation of the P-UE".

[0131] For power reduction in LTE V2X, a partial sensing operation and / or a random selection operation may be introduced. When the partial sensing operation is supported, the terminal can perform the resource sensing operation in some intervals instead of the entire interval within the sensing window, and can select resources based on the result of the partial sensing operation. According to this operation, the power consumption of the terminal can be reduced.

[0132] Rel-14 LTE V2X may only be capable of transmitting and receiving periodic data. In Rel-14 LTE V2X, a terminal can arbitrarily select candidate slots considering a preset minimum number in a resource selection interval (e.g., a selection window), and can perform a partial sensing operation considering a period in units of k×100 ms. k can be signaled by a bitmap (e.g., a bitmap including 10 bits). k can be determined by the position of the bitmap (e.g., the bits included in the bitmap). For example, the 10 bits included in the bitmap can correspond to 1 to 10 from the MSB, and the period can be determined based on the value corresponding to the bit set to 1. The value corresponding to the bit set to 1 can be k.

[0133] If the MSB in the bitmap is set to 1, k can be 1. In this case, the terminal can perform a partial sensing operation considering a 100 ms (=1×100 ms) period. If the next bit of the MSB in the bitmap is set to 1, k can be 2. In this case, the terminal can perform a partial sensing operation considering a 200 ms (=2×100 ms) period. If the LSB in the bitmap is set to 1, k can be 10. In this case, the terminal can perform a partial sensing operation considering a 1000 ms (=10×100 ms) period.

[0134] In Rel-14 LTE V2X, the period (e.g., the period of the partial sensing operation) can be set to 20 ms or 50 ms. The 20-ms period or 50-ms period may not be supported in the resource pool for the P-UE. In the NR communication system, short periods other than {0, 100 ms, 200 ms, …, 1000 ms} can be supported. The short period can be {1 ms, 2 ms, …, 99 ms}. Up to 16 periods can be selected in the resource pool, and the selected periods can be preset for the terminal. The terminal can perform the resource sensing operation and / or the resource (re)selection operation using one or more of the set periods. When the random selection operation is supported, the terminal can randomly select a resource without performing the resource sensing operation. Or the random selection operation can be performed together with the resource sensing operation. For example, the terminal can determine a resource by performing the resource sensing operation and select a resource by performing the random selection operation within the determined resource.

[0135] In LTE V2X that supports Rel-14, the resource pool capable of performing the partial sensing operation and / or the random selection operation can be set independently of the resource pool capable of performing the complete sensing operation. The resource pool capable of performing the random selection operation, the resource pool capable of performing the partial sensing operation, and the resource pool capable of performing both the random selection operation and the partial sensing operation can be set independently. In other words, the random selection operation, the partial sensing operation, or the "random selection operation and partial sensing operation" can be set in each resource pool. When both the random selection operation and the partial sensing operation are set in the resource pool, the terminal can select one of the random selection operation and the partial sensing operation, select a resource by performing the selected operation, and perform sidelink communication using the selected resource.

[0136] In LTE V2X supporting Rel-14, SL data can be transmitted periodically based on the broadcast method. In the NR communication system, SL data can be transmitted based on at least one of the broadcast method, the multicast method, the groupcast method, or the unicast method. Also, in the NR communication system, SL data can be transmitted periodically or aperiodically. The transmitting terminal can transmit SL data to the receiving terminal, and the receiving terminal can transmit HARQ-ACK feedback (e.g., ACK or NACK) for the SL data to the transmitting terminal through the PSFCH. In the present disclosure, the transmitting terminal can mean a terminal that transmits SL data, and the receiving terminal can mean a terminal that receives SL data.

[0137] A terminal with reduced capability (hereinafter referred to as "RedCap terminal") can operate in a specific usage environment. The capability of the RedCap terminal may be lower than that of a normal new radio (NR) terminal, and may also be higher than the capabilities of LTE-MTC (machine type communication) terminals, NB (narrow band)-IoT (internet of things) terminals, and LPWA (Low Power Wide Area) terminals respectively. For example, there can be terminals that require "high data rate and not high latency conditions" (such as surveillance cameras) and / or terminals that require "not high data rate, high latency conditions, and high reliability" (such as wearable devices). To support the terminals described above, the maximum carrier bandwidth can be reduced from 100 MHz to 20 MHz in FR1 and from 400 MHz to 100 MHz in FR2. The number of receiving antennas of the Redcap terminal may be smaller than that of a normal NR terminal. When the carrier bandwidth and the number of receiving antennas decrease, the receiving performance of the RedCap terminal may decrease, and accordingly, the coverage of the RedCap terminal may decrease.

[0138] A communication system (e.g., an NR system) can operate in a frequency band higher than the 52.6 GHz frequency band. As the frequency band in which the communication system operates increases, frequency offset error and phase noise can increase. The use of a large SCS may be necessary for robust operation in such an environment. 60 kHz SCS and / or 120 kHz SCS may be supported in the FR2 band, and additionally 480 kHz SCS and / or 960 kHz SCS may be supported. Also, "physical layer signal and channel design" and "physical layer procedures" with the new SCS may be required. In relation to the initial connection procedure, 120 kHz SSB and / or 240 kHz SSB may be supported in the FR2 band, and additionally 480 kHz SSB and / or 960 kHz SSB may be supported. Here, 120 kHz SSB may mean an SSB transmitted in a radio resource to which 120 kHz SCS is applied, and 240 kHz SSB may mean an SSB transmitted in a radio resource to which 240 kHz SCS is applied. "Initial BWP setting method" and "SSB burst set pattern" may be required to support the new SCS.

[0139] Technologies for improving the data transmission rate in sidelink in Rel-18, supporting operation in unlicensed spectrum, improving performance in FR2 licensed spectrum, and / or co-channel coexistence between LTE SL and NR SL may be discussed.

[0140] For SL (sidelink) communication in an unlicensed band (e.g., unlicensed spectrum), the regulations regarding the transmission band, transmission power, and / or transmission time by using the unlicensed band shall be complied with in the same way as in the NR-U system. The design of sidelink signals and / or channels compliant with the regulations may be necessary. In the present disclosure, SL communication in the unlicensed band may be referred to as SL-U (unlicensed) communication. In the present disclosure, SL communication may mean SL-U communication, the SL communication method may be applied to SL-U communication, and the NR-U communication method may be applied to SL-U communication. In an existing SL system, one SL BWP may be configured, and SL communication may be performed based on a plurality of resource pools configured within the one SL BWP. One SL BWP for SL-U communication may be configured, and the SL-U communication may be performed based on a plurality of resource pools configured within the one SL BWP.

[0141] The transmission of signals and / or channels in SL-U communication shall satisfy the OCB regulations. The design of SL channels (e.g., PSCCH, PSSCH, and / or PSFCH) considering the OCB regulations may be necessary. To satisfy the OCB regulations in NR-U communication, the RBs (resource blocks) for data transmission may be configured to have an interlace (interlace or interlaced) structure. When an interlace structure (e.g., interlace RB structure) is used, the RBs may be configured to have a certain interval in the frequency domain. In this case, the resource allocation for data transmission may be signaled by a combination of a start interlace index (e.g., start RB interlace index) and an interlace length. The RB may mean a PRB (physical resource block).

[0142] In SL-U communication, the subchannel can be configured to have an interleaved RB structure. In this case, the OCB requirements can be satisfied. A subchannel including K interleaves can be configured. K can be a natural number greater than or equal to 1. K (for example, the value of K) can be configured for the terminal through signaling (for example, system information, PC5-RRC signaling, UE-specific RRC signaling, and / or control information). K can be configured in a fixed, semi-fixed, or dynamic manner.

[0143] When one subchannel includes one interleave (for example, one RB interleave) (for example, when K is 1), the interleave index can be the same as the subchannel index. In this case, a separate interleave index may not be necessary. In the present disclosure, the interleave can mean an RB interleave. When one subchannel includes two or more interleaves (for example, when K exceeds 1), the interleave index can be different from the subchannel index. In this case, a separate interleave index can be defined. An interleave can include one or more RBs. The RBs included in the interleave can have an interleave structure.

[0144] In the unlicensed band, the regulation can be defined in units of 20 MHz bands. In NR-U, the RBs corresponding to the 20 MHz band can be defined as an RB set. One BWP can include multiple RB sets. When a communication node attempts to transmit signals simultaneously using multiple RB sets in the unlicensed band, the channel connection method for the transmission operation can be applied differently for DL and UL. In NR-U DL communication, the base station can perform a type 1 channel connection operation for each of the multiple RB sets, and transmission can be performed when the type 1 channel connection operation is successful. The procedure can be a type A channel connection procedure. In NR-U DL communication, the base station can perform a type 1 channel connection operation for one of the multiple RB sets, and can perform a sensing operation during the minimum sensing interval (e.g., 25 us) in the remaining RB sets. When the type 1 channel connection operation and the sensing operation are successful, the base station can perform a transmission operation. The procedure can be a type B channel connection procedure.

[0145] In NR-U UL communication, the terminal can perform a type 1 channel connection operation on all of the multiple channels, and can transmit data when the type 1 channel connection operation (e.g., LBT operation) is successful on all of the multiple channels. In the event that the LBT operation fails on at least one of the multiple channels, the terminal may not transmit data. For general transmission (e.g., PSCCH and / or PSSCH transmission) in SL-U communication, the channel connection procedure in NR-U UL communication can be used. For specific signal and / or channel transmission (e.g., S-SSB and / or PSFCH transmission) in SL-U communication, the channel connection procedure (e.g., type A or type B channel connection procedure) in NR-U DL communication can be used.

[0146] When a plurality of RB sets are configured, a guard band can be set between the RB sets in consideration of the operation with a single RB set. "When there are a plurality of RB sets and the LBT operation for some of the plurality of RB sets is successful", data can be transmitted in the some of the RB sets. In this case, in order to improve the resource efficiency, data transmission can be performed using resources including the resources within the guard band between the RB sets where the LBT operation is successful. Information (e.g., control information) indicating whether data transmission is performed using resources within the guard band between the RB sets can be transmitted through signaling.

[0147] The receiving node (e.g., receiving terminal) can confirm whether data transmission is performed using resources including the resources within the guard band between the RB sets by receiving the control information. An RB set index for each of the plurality of RB sets can be configured for the signaling operation. The control information can be transmitted on a control channel. The receiving node does not know in advance which of the plurality of RB sets are the ones where the LBT operation is successful. Therefore, the receiving node can consider all possible combinations for the plurality of RB sets. In other words, the receiving node can perform the receiving operation for all possible combinations. In this case, the complexity of the receiving node can increase. The transmission on the control channel can be limited within each RB set, different from the transmission on the data channel.

[0148] RB set in SL-U communication, type A channel connection procedure in DL communication, type B channel connection procedure in DL communication, and / or channel connection procedure in UL communication may be applied. Design of channels (e.g., PSCCH, PSSCH, and / or PSFCH) considering the procedures applied in SL-U communication may be necessary. When channels and / or signals are transmitted through multiple RB sets in SL, the subchannel index may be set as a combination of an interleaving index and an RB set index, and may be set separately for each RB set. For example, one or more subchannels may be set within RB set #0, and the index of each of the one or more subchannels may be #0, #1, etc. One or more subchannels may be set within RB set #1, and the index of each of the one or more subchannels may be #0, #1, etc. Each RB set may be composed of one or more interleavings, and subchannels belonging to each RB set may include one or more interleavings. The indexes of subchannels including interleavings having the same index in an RB set may be set identically. For example, the indexes of subchannels including interleaving #0 and #1 in RB set #0 and the indexes of subchannels including interleaving #0 and #1 in RB set #1 may be set identically. When PSSCH is transmitted through multiple subchannels, PSCCH (e.g., PSCCH scheduling PSSCH) may be transmitted in a pre-set resource region within the subchannel having the lowest index. PSCCH scheduling PSSCH may mean PSCCH related to PSSCH.

[0149] The time resource of the preset resource region can include two or three symbols. The frequency resource of the preset resource region can include 10, 12, 15, 20, or 25 RBs. When "a channel and / or a signal is transmitted through a plurality of RB sets and the subchannel has an interleaved RB structure", the PSSCH can be transmitted through an interleave within a guard band between the RB sets, and the PSCCH (for example, the PSCCH that schedules the PSSCH) can be transmitted through a preset resource region within the interleave corresponding to the subchannel having the lowest index. The PSCCH may not be transmitted through an interleave within a guard band between the RB sets.

[0150] The subchannel having the lowest index within a specific RB set among a plurality of RB sets may overlap with a guard band between the plurality of RB sets. In this case, even when the subchannel overlapping with the guard band between the plurality of RB sets is the subchannel having the lowest index within the specific RB set, the terminal may not be able to transmit the PSCCH on the subchannel and may transmit the PSCCH on the next subchannel (for example, the subchannel having the next index). It can be set that the PSCCH is not transmitted through an interleave within a guard band between the RB sets. The setting can be performed through signaling (for example, system information, PC5-RRC signaling, UE-specific signaling, and / or SCI).

[0151] Considering the complexity of the terminal, the resources can be configured such that the PSCCH is transmitted in one RB set (e.g., the RB set with the lowest index). Specifically, the K interleaves included in the subchannel can be appropriately configured so that the resource region for the PSCCH belongs only to one RB set. For example, "when the number of RBs required for PSCCH transmission is 20 and the number of RBs included in one interleave within one RB set is less than 20", the subchannel can include two or more interleaves. In SL communication, the control information can be classified into the first-stage SCI and the second-stage SCI. The first-stage SCI can be transmitted through the PSCCH, and the second-stage SCI can be transmitted through the PSSCH. When the PSSCH is transmitted through multiple RB sets, the second-stage SCI can be transmitted within the guard band between the RB sets. In other words, the second-stage SCI can be mapped within the guard band between the RB sets, the transmission of the second-stage SCI may not be limited within one RB set, and the second-stage SCI can be transmitted in the same manner as the data.

[0152] As another method, when the second-stage SCI is transmitted through the PSSCH, the transmission of the second-stage SCI can be limited within one RB set. In other words, the second-stage SCI can be transmitted in the same manner as the first-stage SCI. When the transmission of the second-stage SCI is limited within one RB set, similar to groupcast communication and / or broadcast communication, if the settings of the RB sets among multiple terminals are different, the transmission of the second-stage SCI can be limited within the common resource region where the resource regions of all terminals overlap. In this case, the information on the RB set through which the PSSCH is transmitted among the multiple RB sets can be transmitted through the SCI (e.g., the first-stage SCI and / or the second-stage SCI). The RB set for PSSCH transmission can be indicated by the start RB set and the number of RB sets (e.g., the number of consecutive RB sets), and the information on the start RB set and the number of RB sets can be signaled. Or the RB set for PSSCH transmission can be indicated by a bitmap, and the bitmap can be signaled.

[0153] As another method, PSCCH transmission in SL-U communication can be performed based on the same or a similar method as PSCCH transmission in NR-U communication. The PSCCH can be transmitted through a preset RB set. The PSCCH can be set to be transmitted in some or all of a plurality of RB sets. In this case, the transmitting terminal can select an RB set in which the LBT operation has succeeded from among the RB sets set for PSCCH transmission, and can transmit the PSCCH in the selected RB set. The receiving terminal can perform a PSCCH monitoring operation in the set RB set. When the LBT operation has succeeded in a plurality of RB sets among the RB sets set for PSCCH transmission, the transmitting terminal can select one RB set from among the plurality of RB sets, and can transmit the PSCCH in the selected one RB set. Or the transmitting terminal can transmit the PSCCH in two or more or all of the plurality of RB sets in which the LBT operation has succeeded. When PSCCH transmission is performed in a plurality of RB sets, the same information can be repeatedly transmitted.

[0154] In SL communication, a terminal can determine the presence or absence of resource usage of other terminals by performing a sensing operation through SCI monitoring. When multiple RB sets are configured, some terminals can perform SL communication using one of the multiple RB sets. A first terminal that performs SL communication using multiple RB sets can transmit an SCI (e.g., a first-stage SCI and / or a second-stage SCI) in a first RB set (e.g., the RB set with the lowest index), and a second terminal can perform a sensing operation in an RB set other than the first RB set (e.g., a second RB set) where the SCI of the first terminal is transmitted. In this case, the second terminal may not be able to perform a sensing operation on the SL transmission (e.g., data transmission) of the first terminal transmitted through multiple RB sets. A data collision may occur between the first terminal and the second terminal in the above situation. For a terminal that does not perform a sensing operation on multiple RB sets, a terminal that transmits data through multiple RB sets can repeatedly transmit an SCI in all RB sets. In this case, the SCI can be transmitted through the lowest subchannel in the scheduling region of each RB set.

[0155] Multiple RB sets can be configured through signaling (e.g., system information, PC5-RRC signaling, UE-specific RRC signaling, and / or control information). Multiple RB sets can be configured fixedly, semi-fixedly, or dynamically. The guard bands between RB sets can be configured in various ways considering various environments. The PC5-RRC connection setup procedure between terminals in SL unicast communication can be performed in advance. The configuration information of multiple RB sets between terminals can be signaled in the PC5-RRC connection setup procedure. The number of RBs for the guard band in the configuration information of multiple RB sets of the first terminal may be different from the number of RBs for the guard band in the configuration information of multiple RB sets of the second terminal. In this case, the larger value of the number of RBs for the guard band of the first terminal and the number of RBs for the guard band of the second terminal can be applied. Here, the first terminal and the second terminal can be unicast terminals that perform unicast communication.

[0156] In SL groupcast communication, a groupcast terminal can transmit the configuration information of a plurality of RB sets. The groupcast terminal may mean a terminal that performs groupcast transmission. All terminals within the group can perform communication based on the configuration information received from the groupcast terminal. The number of RBs for the guard band (e.g., the minimum number of RBs) among a plurality of terminals within the group can be different from each other. In this case, the largest value among the number of RBs for the guard band within the group can be applied. In other words, the guard band can be set considering the maximum number of RBs (e.g., the largest value among the minimum number of RBs). For the above operation, the number of RBs for the guard band (e.g., the minimum number of RBs) can be shared in advance among the terminals within the group. In other words, the terminals within the group can find out in advance the number of RBs for the guard band of other terminals (e.g., the minimum number of RBs). "When the number of RBs for the guard band is not shared within the group" or "when the terminals within the group do not know the number of RBs for the guard band of different terminals", the largest value among the number of RBs that can be set for the guard band within the group can be applied. In other words, the guard band including the most RBs within the group can be set.

[0157] In SL broadcast communication, the number of RBs for the guard band can be set to the largest value among the configurable values. When the number of RB sets that can be configured in the first terminal is different from the number of RB sets that can be configured in the second terminal, groupcast communication and / or broadcast communication can be performed within a common resource area where the resource areas of all terminals overlap. As another method, regardless of the presence or absence of the configuration of a plurality of RB sets in SL groupcast communication and SL broadcast communication, SL communication (e.g., SL groupcast communication and / or SL broadcast communication) can be performed with one RB set.

[0158] To ensure the number of attempts of the LBT operation in SL-U communication, multiple starting points can be set. The starting point can mean the time when data transmission starts, and the LBT operation for the data transmission can be performed before the starting point. When it is set to start data transmission at the start point of each slot, if the LBT operation cannot succeed before the start point of each slot, the terminal cannot start data transmission in the corresponding slot. Multiple starting points (for example, symbol #0 and symbol #X) can be set for each slot. X can be a natural number of 1 or more. In this case, even if the LBT operation cannot succeed before the first starting point of the slot (for example, symbol #0), the terminal can start data transmission if the LBT operation succeeds before the next starting point of the slot (for example, symbol #X).

[0159] To ensure the number of attempts of the LBT operation and / or improve resource efficiency, multiple starting points can be set for the terminal. The more starting points are set, the more the number of attempts of the LBT operation can increase and the resource efficiency can improve. However, when multiple starting points are set, calculations of the transport block (TB) size, PSCCH mapping, mapping of the second-stage SCI, DMRS mapping, etc. have to be newly defined considering each of the multiple starting points. Therefore, the complexity of the communication system (for example, the SL-U system) can increase. Considering the above problems, it is preferable to set an appropriate number of starting points. For example, it is preferable to set two starting points.

[0160] The first starting point among the two starting points can be the symbol #0 or the symbol set by sl-StartSymbol. In SL communication (e.g., SL-U communication), data transmission can be performed in a specific interval starting from a specific symbol (e.g., the symbol set by sl-StartSymbol) within the slot rather than the entire slot. The specific symbol can be set to one of the symbols from symbol #0 to symbol #7. The specific interval can include 7, 8, 9, 10, 11, 12, 13, or 14 symbols. The symbol set by sl-StartSymbol can be other symbols (e.g., symbol #Y) rather than symbol #0. Y can be a natural number greater than or equal to 1.

[0161] When the first starting point of SL communication (e.g., SL-U communication) is set by sl-StartSymbol, the LBT operation can be performed considering the symbol set by the sl-StartSymbol. In this case, since at least one resource (e.g., channel) within symbols #0 to #Y can be pre-empted by other systems coexisting in the unlicensed band, it is preferable to always fix the first starting point at symbol #0 regardless of the value of sl-StartSymbol. "When the value of sl-StartSymbol is greater than 0 and the LBT operation is successful", the terminal can perform the transmission operation of any signal or the transmission operation of the signal through CPE (cyclic prefix extension) at symbol #0, and can perform the actual SL communication (e.g., SL-U communication) starting from the symbol set by sl-StartSymbol.

[0162] The second starting point among the two starting points can be appropriately set within a slot considering the LBT operation (e.g., LBT mode). For example, the second starting point can be set at symbol #4 or after symbol #4. When data transmission is performed at the second starting point, setting of the DMRS mapping pattern considering the data transmission may be necessary. In SL communication (e.g., SL-U communication), multiple DMRS mapping patterns for multiple DMRSs can be set through higher layer signaling. One of the multiple DMRS mapping patterns for data transmission can be signaled by SCI. The number of DMRSs can be set according to the length of PSSCH transmission. For example, the number of DMRSs can be set to 2, 3, or 4. In the time domain, the DMRS mapping pattern can be determined based on the length of PSSCH transmission and / or the number of DMRSs. The length of PSSCH transmission may mean the PSSCH length. In other words, the length of PSSCH transmission may mean the number of symbols scheduled for PSSCH transmission.

[0163] The DMRS mapping pattern can be set considering multiple starting points. The DMRS mapping pattern considering the first starting point (hereinafter referred to as the "first DMRS mapping pattern") can be set the same as the existing DMRS mapping pattern. The DMRS mapping pattern considering the second starting point (hereinafter referred to as the "second DMRS mapping pattern") can be set separately. When the first DMRS mapping pattern and the second DMRS mapping pattern are set independently, the number of the first DMRS mapping patterns can be different from the number of the second DMRS mapping patterns. In this case, the number of bits for indicating the first DMRS mapping pattern by SCI can be set differently from the number of bits for indicating the second DMRS mapping pattern by SCI. For example, "when the number of the first DMRS mapping patterns is 3 and the number of the second DMRS mapping patterns is 2", the number of bits required to indicate the first DMRS mapping pattern can be 2, and the number of bits required to indicate the second DMRS mapping pattern can be 1.

[0164] When the DMRS mapping pattern is set independently by the starting point, the overhead of the upper layer signaling for setting the DMRS mapping pattern may increase, and the number of bits for indicating the DMRS mapping pattern within the SCI may change. According to the above situation, the receiving complexity of the terminal may increase. When the first DMRS mapping pattern is set, the second DMRS mapping pattern may be implicitly indicated by the first DMRS mapping pattern. For example, the number (M) of the second DMRS mapping pattern may be less than or equal to the number (N) of the first DMRS mapping pattern. Specifically, the number (M) of the second DMRS mapping pattern may be set to the maximum number considering the length of the PSSCH transmission within the number (N) of the first DMRS mapping pattern.

[0165] The number of bits for indicating one DMRS mapping pattern (for example, the DMRS mapping pattern for PSSCH transmission) within the SCI may be determined based on N among the number (N) of the first DMRS mapping pattern and the number (M) of the second DMRS mapping pattern. For example, the number of bits for indicating one DMRS mapping pattern within the SCI may be log2(N). In this case, one DMRS mapping pattern among the first DMRS mapping patterns may be indicated by log2(N) bits included in the SCI, and one DMRS mapping pattern among the second DMRS mapping patterns may be indicated by log2(N) bits included in the SCI. In other words, the number of bits for indicating one DMRS mapping pattern among the second DMRS mapping patterns may be set to be the same as the number of bits for indicating one DMRS mapping pattern among the first DMRS mapping patterns.

Table 6

[0166] The above Table 6 is the PSCCH length (l d) and the number of PSSCH DMRSs can indicate the DMRS mapping pattern in the time domain. The PSSCH DMRS can be the DMRS used for the transmission and reception of the PSSCH. For example, when the first starting point is symbol #0, the PSSCH length (l d ) can correspond to a length of 13 symbols. When the PSCCH duration includes 2 symbols, the number of DMRSs can be 2, 3, or 4. In this case, the positions of the symbols where the DMRSs are mapped (for example, the DMRS mapping pattern) can be {3, 10}, {1, 6, 11}, or {1, 4, 7, 10}. The DMRS mapping pattern can be indicated by 2 bits included in the SCI.

[0167] When the second starting point is symbol #4, the PSSCH length (l d ) can correspond to a length of 9 symbols. When the number of the first DMRS mapping patterns is 3, the number of the second DMRS mapping patterns can be determined to be at most the maximum number (for example, 2) within the number (for example, the number of the first DMRS mapping patterns) without a separate setting. In other words, the number of the second DMRS mapping patterns can be implicitly determined considering the number of the first DMRS mapping patterns. The signaling for the above operation can be performed by 2 bits for indicating the first DMRS mapping pattern in the SCI. According to the above method, since separate signaling for indicating the second DMRS mapping pattern is not required, the signaling overhead can be reduced. Since the number of bits for indicating the DMRS mapping pattern in the SCI is not changed, the reception complexity of the terminal can be reduced.

[0168] When multiple starting points are set in SL-U communication, a method for calculating the TB size considering the multiple starting points may be required. The number of TBs can be calculated based on the number of available resource elements (REs) and the modulation and coding scheme (MCS). When multiple starting points are set, the number of available REs can vary depending on the position of the starting point. To avoid confusion regarding the TB size between the transmitting terminal and the receiving terminal, the number of reference symbols can be set. The number of reference symbols for calculating the TB size can be defined based on the first starting point. "When the TB size is calculated based on the first starting point, but the actual data transmission is performed from the second starting point", some data may not be transmitted by rate-matching. In this case, the receiving performance may deteriorate.

[0169] As another method, the number of reference symbols for calculating the TB size can be defined based on the second starting point. "When the TB size is calculated based on the second starting point, but the actual data transmission is performed from the first starting point", a lot of resources may be available for the data transmission. In this case, some information (e.g., some data) may be additionally transmitted through rate-matching. Therefore, the receiving performance may improve, but the resource efficiency may decrease. In other words, since a TB smaller than the calculated TB size is transmitted, the resource efficiency may decrease.

[0170] As yet another method, the reference points for TB size calculation may be set for each resource pool through signaling (e.g., system information, RRC messages). Depending on the situation of the communication system (e.g., SL system, SL-U system), the number of reference symbols for TB size calculation may be set to be determined based on the first starting point or the second starting point. For example, in an environment where a lot of other traffic coexists, the success probability of the LBT operation may not be high. In this case, the number of reference symbols for TB size calculation may be set to be determined based on the second starting point. In an environment with little traffic, the success probability of the LBT operation may be high. In this case, the number of reference symbols for TB size calculation may be set to be determined based on the first starting point.

[0171] As yet another method, the reference points for TB size calculation may be dynamically signaled according to the successful time of the LBT operation of the transmitting terminal. Specifically, the data transmission time due to the success of the LBT operation may be the first starting point or the second starting point, and the transmitting terminal can dynamically signal the reference points for TB size calculation using an SCI (e.g., a 1-bit indicator included in the first-stage SCI and / or the second-stage SCI) according to the data transmission time.

[0172] When multiple starting points are set in SL-U communication, an AGC symbol design considering the multiple starting points may be required. For example, when multiple RB sets are set within a resource pool (or BWP), SL transmission may be performed at different starting points within different RB sets. In this case, AGC issues may occur.

[0173] FIG. 15a is a conceptual diagram illustrating a first embodiment of AGC symbols for FDM SL transmission with multiple RB sets, and FIG. 15b is a conceptual diagram illustrating a second embodiment of AGC symbols for FDM SL transmission with multiple RB sets.

[0174] Referring to FIG. 15a, the AGC symbol can be set at one starting point. SL TX #0 can be performed from the first starting point within RB set #0, and SL TX #1 can be performed from the second starting point within RB set #1. In this case, the received power can be increased by SL TX #1, and accordingly, an AGC issue (e.g., clipping) for SL TX #0 can occur. An embodiment in FIG. 15b can be proposed to solve the AGC issue.

[0175] Referring to FIG. 15b, the AGC symbol can be set at multiple starting points. In this case, even when SL TX #0 and SL TX #1 are performed, a new AGC operation can be performed so that no AGC issue occurs. However, since the AGC symbol is difficult to be used for data transmission, when the AGC symbol is set at multiple starting points, the resource efficiency can be reduced and the receiving complexity of the terminal can be increased. To solve the above problem, when one terminal performs SL transmission through multiple RB sets (e.g., all RB sets), it is preferable that the one terminal uses only one AGC symbol even when multiple AGC symbols are set.

[0176] For example, when the transmission is performed from the first starting point, the terminal can perform the AGC operation using the first AGC symbol (e.g., the AGC symbol set at the first starting point), and can use the second AGC symbol (e.g., the AGC symbol set at the second starting point) for data transmission. In other words, the terminal can transmit data without performing the AGC operation with the second AGC symbol. As another example, when the transmission is performed from the second starting point, the terminal can perform the AGC operation using the second AGC symbol.

[0177] When "only one set of RBs is configured within a resource pool (or BWP) and multiple AGC symbols are configured", it is preferable for the terminal to perform the AGC operation using only one AGC symbol. Multiple terminals can perform different SL transmissions (e.g., different SL-U transmissions) with each other through multiple sets of RBs. In this case, when the terminal determines that the start positions of the SL transmissions (e.g., SL-U transmissions) of other terminals are the same, the terminal can also use only one AGC symbol even when multiple AGC symbols are configured.

[0178] Within the SL resources (e.g., SL-U resources) configured in the above manner, the PSFCH can be periodically configured as in the embodiments of FIGS. 10 and / or 11. The PSFCH can be a channel used for transmitting HARQ-ACK (e.g., ACK or NACK) for data. There can be protection symbols for changing the transmission and reception operations before the "AGC operation + PSFCH transmission". The terminal can perform the LBT operation with the protection symbols for PSFCH transmission, and it may not be able to transmit the PSFCH if the LBT operation fails. The transmitting terminal can determine whether to retransmit the data based on the HARQ-ACK (e.g., ACK or NACK) received through the PSFCH. When a reception failure of the data is confirmed at the receiving terminal, the transmitting terminal can perform the data retransmission operation. The PSFCH can be a channel that plays an important role in improving the reliability of SL communication. It is preferable to ensure PSFCH transmission in SL-U communication.

[0179] In NR-U communication, the time during which channel and / or signal transmission is possible due to the successful LBT operation of a terminal or a base station can be defined as COT (channel occupancy time). Channel and / or signal transmission can be possible within the COT. The base station can start the COT and share the COT with the terminal. Or the terminal can start the COT and share the COT with the base station. The said operation can be referred to as "COT sharing". The terminal can transmit channels and / or signals without performing the LBT operation within the COT shared by the base station. Or the terminal can transmit channels and / or signals after performing the LBT operation in a short interval within the COT shared by the base station. The base station can transmit channels and / or signals without performing the LBT operation within the COT shared by the terminal. Or the base station can transmit channels and / or signals after performing the LBT operation in a short interval within the COT shared by the terminal. The LBT operation in the short interval can be a type 2 LBT operation. The interval during which the type 2 LBT operation is performed may be shorter than the interval during which the LBT operation for initial COT acquisition (for example, type 1 LBT operation) is performed.

[0180] The said COT sharing can be introduced into SL-U communication. The first terminal can perform the LBT operation, start the COT when the LBT operation is successful, and share the COT with the second terminal. The second terminal can transmit SL channels and / or signals without performing the LBT operation within the COT shared by the first terminal. Or the second terminal can transmit SL channels and / or signals after performing a simplified LBT operation (for example, type 2 LBT operation) within the COT shared by the first terminal.

[0181] The COT sharing can be applied to the SL data transmission procedure and / or the PSFCH transmission procedure. The first terminal can perform an LBT operation (e.g., a type 1 LBT operation) to transmit SL data to the second terminal, can secure a COT if the LBT operation is successful, and can transmit the SL data to the second terminal within the COT. The first terminal can share the remaining COT period in the COT with the second terminal after transmitting the SL data to the second terminal within the COT. In this case, the second terminal can receive the SL data from the first terminal and can transmit a HARQ-ACK for the SL data to the first terminal through the PSFCH within the remaining COT period. The PSFCH can be set by a specific period (e.g., 1, 2, or 4 logical slots).

[0182] As shown in the embodiment of FIG. 11, a time offset for the processing of the receiving terminal can be set between data reception (e.g., PSSCH reception) and PSFCH transmission. The time offset can be set by sl-MinTimeGapPSFCH. The time offset can be 2 or 3 logical slots. According to the time offset, the second terminal may not be able to transmit a HARQ-ACK for the data within the COT (e.g., the remaining COT period) shared by the first terminal after receiving the data from the first terminal. In other words, if the difference between the PSSCH and the PSFCH occasion within the COT in the time domain is smaller than the time offset, the second terminal may not be able to perform PSFCH transmission within the COT.

[0183] FIG. 16 is a conceptual diagram illustrating a first embodiment of a PSFCH transmission method within a COT.

[0184] Referring to FIG. 16, the PSFCH period can be set with 4 slots, and sl-MinTimeGapPSFCH can indicate 3 slots. The first terminal can transmit PSSCH within the COT and can receive the PSFCH for the PSSCH. The COT can be started by the first terminal. The first terminal can transmit PSSCH #0 to PSSCH #5 to the second terminal within the COT. The second terminal can receive PSSCH #0 to PSSCH #5 from the first terminal and can transmit the PSFCH for PSSCH #0 to PSSCH #5 to the first terminal. PSSCH #0 to PSSCH #5 can be received by the same terminal or different terminals from each other.

[0185] Considering sl-MinTimeGapPSFCH (e.g., 3 slots), the PSFCH corresponding to PSSCH #0, #1, and #2 (e.g., PSFCH occasion, PSFCH transmission occasion, or PSFCH resource) can be located in slot #n + 12 within the COT started by the first terminal. Since the PSFCH is located within the COT, the second terminal can transmit the PSFCH to the first terminal in slot #n + 12 after performing a simplified LBT operation (e.g., type 2 LBT operation). In this case, stable transmission of the PSFCH can be ensured.

[0186] Considering sl-MinTimeGapPSFCH (e.g., 3 slots), the PSFCH corresponding to PSSCH #3 to PSSCH #5 can be located in slot #n + 16. In other words, the PSFCH corresponding to PSSCH #3 to PSSCH #5 can be located outside the COT started by the first terminal. The second terminal can perform a new LBT operation (e.g., type 1 LBT operation) to transmit the PSFCH in slot #n + 16, and there may be a case where the PSFCH cannot be transmitted if the new LBT operation fails. Considering the failure of the LBT operation, additional PSFCH occasions can be set.

[0187] The base station or the transmitting terminal can set additional PSFCH occasions for the terminal (e.g., the receiving terminal and / or the transmitting terminal) through signaling. For example, the base station or the transmitting terminal can transmit a single message containing the setting information of the existing PSFCH occasion and the setting information of the additional PSFCH occasion to the terminal (e.g., the receiving terminal and / or the transmitting terminal). As another method, for example, the base station or the transmitting terminal can transmit a first message containing the setting information of the existing PSFCH occasion to the terminal (e.g., the receiving terminal and / or the transmitting terminal), and can transmit a second message containing the setting information of the additional PSFCH occasion to the terminal (e.g., the receiving terminal and / or the transmitting terminal). The first message and the second message can be independent messages.

[0188] The existing PSFCH transmission resource (e.g., the existing PSFCH occasion) can be the first PSFCH occasion after the slot indicated by sl-MinTimeGapPSFCH from the time of receiving the PSSCH. Up to N PSFCH occasions can be set for SL-U communication. N can be a natural number. The N PSFCH occasions can include the first PSFCH occasion (e.g., the existing PSFCH occasion). Or the N PSFCH occasions may not include the first PSFCH occasion (e.g., the existing PSFCH occasion). In this case, 1 existing PSFCH occasion and N additional PSFCH occasions can be set, and the total number of PSFCH occasions can be N + 1.

[0189] If the terminal fails in PSFCH transmission in the first PSFCH occasion, it can attempt PSFCH transmission in the second PSFCH occasion. The failure of PSFCH transmission may mean the failure of the LBT operation for the PSFCH transmission. Or the failure of PSFCH transmission may mean the failure of PSFCH transmission due to low priority or insufficient transmission power. If N PSFCH occasions are set, the execution of up to N LBT operations can be guaranteed. If the N LBT operations fail, the terminal can drop the PSFCH transmission. According to the method, stable transmission of PSFCH can be guaranteed. N can be set for the terminal through signaling (such as system information, PC5-RRC signaling, and / or UE-specific RRC signaling). N can be set fixedly or non-fixedly. Or N can be set dynamically by control information (such as DCI, SCI). N can be set separately for each resource pool.

[0190] Up to N PSFCH occasions can be applied to other PSFCH transmissions except for the PSFCH transmission for PSCCH within the COT. Up to 1 PSFCH occasion can be set for PSFCH transmission within the COT. The PSFCH period, transmission-related timeline, and / or COT duration can be preset. Therefore, the terminal can grasp in advance whether PSFCH transmission is possible within the COT. Or the information on whether PSFCH transmission is possible within the COT can be transmitted through signaling (such as a 1-bit indicator). The terminal can confirm the maximum number of PSFCH occasions (such as 1 or N) for each PSFCH transmission based on the method, and can perform PSFCH transmission considering the confirmed maximum number of PSFCH occasions.

[0191] As another method, regardless of the availability of PSFCH transmission within the COT, a maximum of N PSFCH occasions can be set for all PSFCH transmissions. In this case, PSFCHs that could not be transmitted due to the failure of the LBT operation and / or other reasons (e.g., dropping of PSFCH transmission due to priority) may be transmissible. However, the terminal receiving the PSFCH must perform a monitoring operation on N PSFCH occasions. Therefore, the reception complexity of the PSFCH may increase. Even when a maximum of N PSFCH occasions are guaranteed, the use of multiple PSFCH occasions may be limited to specific situations.

[0192] For example, even when a maximum of N PSFCH occasions are guaranteed, multiple PSFCH occasions can be set to be used only in situations where the LBT operation fails. Even when a maximum of N PSFCH occasions are guaranteed, multiple PSFCH occasions can be set to be used only in situations where PSFCH transmission is dropped. Even when a maximum of N PSFCH occasions are guaranteed, multiple PSFCH occasions can be set to be used only in situations where PSFCH retransmission is performed. The situations in which multiple PSFCH occasions are used when a maximum of N PSFCH occasions are guaranteed can be set by signaling (e.g., system information, PC5-RRC signaling, UE-specific RRC signaling, control information). The situations in which multiple PSFCH occasions are used when a maximum of N PSFCH occasions are guaranteed can be set fixedly, semi-fixedly, or dynamically. The situations in which multiple PSFCH occasions are used when a maximum of N PSFCH occasions are guaranteed can be set separately for each resource pool.

[0193] When a plurality of PSFCH occasions are configured, the transmitting terminal can transmit to the receiving terminal an SCI including information indicating whether the plurality of PSFCH occasions are used (e.g., whether they are applicable). The SCI can further include data scheduling information. The receiving terminal can receive the SCI from the transmitting terminal and can confirm whether the plurality of PSFCH occasions are used based on the information included in the SCI. When the plurality of PSFCH occasions are not used, the receiving terminal can attempt to transmit a HARQ-ACK (e.g., PSFCH format) for the data received from the transmitting terminal on one PSFCH occasion. When the plurality of PSFCH occasions are used, the receiving terminal can attempt to transmit a HARQ-ACK (e.g., PSFCH format) for the data received from the transmitting terminal on the plurality of PSFCH occasions.

[0194] When a plurality of PSFCH occasions are configured, the PSFCH resource selection procedure can be newly defined. The terminal can select a PSFCH RB based on the slot and / or subchannel position where the PSSCH is transmitted, and can select a specific PSFCH resource (e.g., a specific PSFCH RB and / or a specific sequence index) based on the TX ID and / or RX ID among the multiplexable plurality of PSFCH resources (e.g., a plurality of sequences on a plurality of PSFCH RBs). The RX ID can be set to 0 according to the HARQ-ACK (e.g., ACK, NACK) transmission mode.

[0195] When multiple PSFCH occasions are configured, to avoid collision with existing PSFCH resources, the PSFCH occasion index can be additionally considered. The selection operation of existing PSFCH resources can be the same as the selection operation when the PSFCH occasion index is 0 (e.g., PSFCH occasion #0). Thereafter, for additional PSFCH occasions, an additional PSFCH occasion index (e.g., PSFCH occasion #1, #2, …, #N-1) can be applied. According to the above method, collision with existing PSFCH resources can be prevented. The PSFCH occasion index can be applied in the procedure of "selecting PSFCH RBs based on the positions of slots and / or subchannels" and / or the procedure of "selecting PSFCH resources among the selected PSFCH RBs".

[0196] Specifically, when the PSFCH occasion index is n, in the procedure of selecting PSFCH RBs, i + n can be applied instead of i to indicate the slot index (e.g., the slot index can mean the slot index within the PSFCH period and can be different from the general slot index), and j + n can be applied instead of j to indicate the subchannel index. When the above method is applied in the procedure of selecting PSFCH resources among the selected PSFCH RBs, P ID +M ID can be replaced by P ID +M ID +n can be applied. As another method, the number of PSFCH RBs for each of the N PSFCH occasions can be set to N, and the N PSFCH occasions can be set to be selected in a one-to-one correspondence with N PRSCH RBs.

[0197] When the PSFCH occasion index is 0, the PSFCH resource (e.g., cyclic shift) can be set as the one selected within the first PSFCH RB among the N PSFCH RBs. When the PSFCH occasion index is 1, the PSFCH resource (e.g., cyclic shift) can be set as the one selected within the second PSFCH RB among the N PSFCH RBs. When the PSFCH occasion index is 2, the PSFCH resource (e.g., cyclic shift) can be set as the one selected within the third PSFCH RB among the N PSFCH RBs. When the PSFCH occasion index is N - 1, the PSFCH resource (e.g., cyclic shift) can be set as the one selected within the Nth PSFCH RB among the N PSFCH RBs.

[0198] When multiple PSFCH occasions are configured, the PSFCH resources corresponding to the additional PSFCH occasions can be configured independently of the existing PSFCH resources. The PSFCH resources can be configured separately for each resource pool. The PSFCH resources can be indicated by a bitmap. The resources for multiple PSFCH occasions, being separate from the existing PSFCH resources, can be indicated by a bitmap. The existing PSFCH resources can be used for PSFCH transmissions (e.g., existing PSFCH transmissions) corresponding to PSFCH occasion #0. The PSFCH resources for additional PSFCH occasions can be used for PSFCH transmissions corresponding to "PSFCH occasion #1, #2, …, #N - 1".

[0199] FIG. 17a is a conceptual diagram illustrating a first embodiment of a resource configuration method for multiple PSFCH occasions, and FIG. 17b is a conceptual diagram illustrating a second embodiment of a resource configuration method for multiple PSFCH occasions.

[0200] Referring to FIGS. 17a and 17b, PSFCH resources for N PSFCH occasions can be set. Here, N can be 4. When N PSFCH occasions are set, the PSFCH resources corresponding to the remaining N - 1 PSFCH occasions (excluding the first PSFCH occasion, e.g., the existing PSFCH occasion) can be set independently of the PSFCH resources corresponding to the first PSFCH occasion. The PSFCH resources corresponding to the first PSFCH occasion can be the existing PSFCH resources and / or the PSFCH resources corresponding to PSFCH occasion #0.

[0201] In the embodiment of FIG. 17a, each of the PSFCH resources corresponding to 3 PSFCH occasions can be set independently. For example, PSFCH resource #1 corresponding to PSFCH occasion #1 can be set, PSFCH resource #2 corresponding to PSFCH occasion #2 can be set, and PSFCH resource #3 corresponding to PSFCH occasion #3 can be set. PSFCH resource #1, PSFCH resource #2, and PSFCH resource #3 can be non - overlapping with each other.

[0202] In the embodiment of FIG. 17b, one PSFCH resource (e.g., a common PSFCH resource area) corresponding to 3 PSFCH occasions (e.g., N - 1 PSFCH occasions) can be set. In this case, in order to prevent collisions during PSFCH transmission among the 3 PSFCH occasions, the application of the PSFCH occasion index in the selection procedure of the PSFCH resource (e.g., the PSFCH resource within the common PSFCH resource area) may be necessary. In the embodiments of FIGS. 17a and / or 17b, the PSFCH resources are set in a localized form in the frequency domain, but the PSFCH resources can be set in other forms. For example, the PSFCH resources can be set in a distributed form in the frequency domain. The PSFCH resources can be indicated by a bitmap.

[0203] To satisfy the OCB regulation in the unlicensed band, the transmission can be performed using the interleaved RBs. Not only the subchannel index but also the interleaving index can be set. When transmission using a plurality of RB sets is possible, the scheduling information can include the RB set index. When the interleaving index and the RB set index exist, the interleaving index and the RB set index can be used to determine the PSFCH resources (e.g., the PSFCH resource region).

[0204] In SL communication, the subchannel index and the slot index of the PSSCH can be used to determine the RB sub-group (e.g., one or more pre-set RBs) for PSFCH transmission. The source ID (e.g., TX ID) and / or the destination ID (e.g., RX ID) can be used to determine the RB index within the RB sub-group and the cyclic shift pair index for the RB corresponding to the RB index. The interleaving index and / or the RB set index can be used to determine at least one of the RB sub-group, the RB index, or the cyclic shift pair index.

[0205] The interleaving index can replace the subchannel index. The interleaving index can be used instead of the subchannel index in the procedure for determining the RB sub-group. The RB set index can be applied in the procedure for determining the RB sub-group. The subchannel index can be set in combination with the interleaving index and the RB set index. In this case, the RB sub-group can be determined considering the subchannel index instead of the "interleaving index and the RB set index". To determine the RB sub-group, both the subchannel index and the slot index can be considered.

[0206] In an unlicensed band, a communication node (e.g., a base station, a terminal) can perform the LBT operation, and if the LBT operation is successful, it can obtain a channel and / or a signal transmission opportunity (e.g., COT), and can transmit a channel and / or a signal during the obtained transmission opportunity. If transmission is not performed for a certain period of time (e.g., T gap ) or more within the transmission opportunity, the communication node may lose the transmission opportunity. Thereafter, when transmission is required again, the communication node can perform the LBT operation, and if the LBT operation is successful, it can perform transmission.

[0207] The PSFCH can be transmitted within the COT, and there can be a guard symbol for changing the transmission and reception operation between the PSSCH resource (e.g., PSSCH symbol) and the PSFCH resource (e.g., PSFCH symbol). If the length of the guard symbol is longer than a certain period of time (e.g., T gap ), the communication node can perform the LBT operation for PSFCH transmission within the COT. If the LBT operation fails, the communication node cannot perform PSFCH transmission. To solve the above problem, the communication node can reduce the length of the guard symbol by extending the CP (cyclic prefix) of the PSFCH. If the length of the remaining guard symbol due to the CP extension of the PSFCH is less than T gap , the communication node can perform PSFCH transmission without performing the LBT operation within the COT. Therefore, the problem of PSFCH transmission failure due to the failure of the LBT operation within the COT can be solved.

[0208] In the unlicensed band, the channel and / or the transmission band of the signal can be set to satisfy the OCB regulations. Since the PSFCH format 0 includes one RB, the PSFCH format 0 cannot satisfy the OCB regulations. A method for solving the above problem is required. To satisfy the OCB regulations, the PSFCH format 0 can be set to have an interleaved structure. In this case, the PSFCH format 0 can be dispersed in the frequency domain (e.g., the entire channel bandwidth, the frequency region within the resource pool). The PSFCH format 0 can be repeatedly transmitted. When "in the frequency region within the resource pool, the PSFCH format 0 is dispersed and the PSFCH format 0 is repeatedly transmitted", the number of repetitions of the PSFCH format 0 and / or the interval for the PSFCH format 0 repeated in the frequency domain can be implicitly confirmed in consideration of the OCB regulations and / or the resource pool (e.g., the entire resource pool). As another method, the number of repetitions of the PSFCH format 0 and / or the interval for the PSFCH format 0 repeated in the frequency domain can be explicitly signaled. For example, the "number of repetitions of the PSFCH format 0 and / or the interval for the PSFCH format 0 repeated in the frequency domain" can be signaled together with the setting information of the resource pool.

[0209] According to the above method, since the same PSFCH format 0 is repeatedly transmitted in the frequency domain, the OCB regulations can be satisfied. The reception performance of the PSFCH (e.g., the PSFCH format 0) can be improved. When the same PSFCH format 0 is repeatedly transmitted in the frequency domain, more resources are required compared to the existing PSFCH transmission procedure, so the resource efficiency can be reduced. As yet another method, a new PSFCH format can be set to have an interleaved structure in the frequency domain (e.g., the entire frequency domain), and the number of RBs for the new PSFCH format can be set to satisfy the OCB regulations.

[0210] The existing PSFCH format 0 can be transmitted through one RB. The existing PSFCH format 0 can be composed of a low PAPR (peak to average power ratio) sequence (e.g., Zadoff-Chu sequence) with "sequence length = 12". When the number of RBs satisfying the OCB regulation is M, the new PSFCH format can be composed of a low PAPR sequence with "sequence length = M × 12". M can be a natural number. The new PSFCH format can have an interleaved structure. The new PSFCH format can be dispersed and transmitted over the channel bandwidth (e.g., the entire channel bandwidth). In this case, since the length of the sequence increases, the number of feedback information that can be multiplexed in the new PSFCH format can increase compared to the existing PSFCH format 0. The feedback information can mean HARQ-ACK, HARQ feedback information, HARQ response, and / or HARQ information bits. Considering the number of feedback information that can be multiplexed in the new PSFCH format, the mapping relationship between a specific sequence and the feedback information in the new PSFCH format can be defined.

[0211] FIG. 18a is a conceptual diagram illustrating a first embodiment of a PSFCH transmission method, and FIG. 18b is a conceptual diagram illustrating a second embodiment of a PSFCH transmission method.

[0212] Referring to FIG. 18a, the PSFCH format 0 (e.g., the existing PSFCH format 0) can be dispersed and transmitted in the frequency domain. The same PSFCH format 0 can be repeatedly transmitted in the frequency domain. The transmission of the PSFCH format 0 in the embodiment of FIG. 18a can satisfy the OCB regulation. Cyclic shift hopping in units of RBs can be applied in the embodiment of FIG. 18a.

[0213] Referring to FIG. 18b, a new PSFCH format with a long sequence can be transmitted in a frequency domain dispersion manner. The new PSFCH format can be defined as PSFCH format 1. In the embodiment of FIG. 18b, the transmission of the new PSFCH format can satisfy the OCB regulation. The PAPR when the new PSFCH format is repeatedly transmitted in the frequency domain may be higher than the PAPR when the existing PSFCH format is dispersion-transmitted in the frequency domain. To reduce the PAPR, cyclic shift hopping in RB units can be applied in the embodiment of FIG. 18b.

[0214] As another method, the feedback information can be transmitted through the existing PSFCH format 0, and in order to satisfy the OCB regulation, the transmission through the redundant RB can be performed. The redundant RB can be commonly applied to multiple terminals, and the terminal can perform the "PSFCH transmission operation" and the "transmission operation of any signal (for example, a predefined signal) on the redundant RB" simultaneously. According to the above method, the OCB regulation can be satisfied. Since the signal transmitted on the redundant RB does not contain special information, the resource efficiency may decrease due to the signal transmission on the redundant RB. Therefore, the redundant RB can include the minimum RB that satisfies the OCB regulation.

[0215] The redundant RB can be set in a dispersed manner in the frequency domain (for example, the entire frequency region). The redundant RB can be commonly applied to all terminals. The redundant RB can be set so as not to overlap with the RB for the existing PSFCH transmission. The position of the redundant RB can be set for the terminal through signaling (for example, system information, PC5-RRC signaling, UE-specific RRC signaling, control information). The redundant RB can be set fixedly, semi-fixedly, or dynamically. The redundant RB can be set for each resource pool.

[0216] The position of the actual PSFCH transmission can be set based on the position of the PSSCH (e.g., slot position), subchannel position, TX ID, RX ID, and / or PSFCH occasion index related to the actual PSFCH transmission. The redundant RB can be set (e.g., selected) considering the position of the actual PSFCH transmission. The resources for PSFCH transmission can be preset for each resource pool, and the redundant RB can be set (e.g., selected) considering the resources for the PSFCH transmission. All or part of the redundant RB can be selected according to the position of the PSFCH transmission (e.g., the actual PSFCH transmission). The selection procedure of the redundant RB according to the position of the PSFCH transmission can be predefined. As another method, the terminal can specifically select the redundant RB.

[0217] For example, the terminal can transmit signals with the redundant RB excluding the RB adjacent to the RB where the PSFCH is transmitted (e.g., dedicated RB) among the total redundant RB. The excluded RB can be the RB that satisfies a specific criterion. The RB that satisfies the specific criterion can be the RB within a certain frequency interval or within a certain number of RBs from the RB where the PSFCH is transmitted. When the total RBs are included in the RBs within a certain number of RBs, the total RBs can be defined as the RBs that satisfy the specific criterion. Or when some of the RBs are included in the RBs within a certain number of RBs, some of the RBs can be defined as the RBs that satisfy the specific criterion. When a part of the RB (e.g., some subcarriers) belongs to the RBs within a certain frequency interval or within a certain number of RBs, the communication node can determine that some or all of the RB satisfies the specific criterion.

[0218] The certain frequency interval and / or the certain number of RBs can be set for the terminal through signaling (e.g., system information, PC5-RRC signaling, UE-specific RRC signaling, control information). The certain frequency interval and / or the certain number of RBs can be set fixedly, semi-fixedly, or dynamically. The certain frequency interval and / or the certain number of RBs can be set for each resource pool.

[0219] FIG. 19a is a conceptual diagram illustrating a first embodiment of PSFCH transmission having redundant RB, FIG. 19b is a conceptual diagram illustrating a second embodiment of PSFCH transmission having redundant RB, and FIG. 19c is a conceptual diagram illustrating a third embodiment of PSFCH transmission having redundant RB.

[0220] Referring to FIGS. 19a to 19c, both "PSFCH transmission" and "transmission of a signal (e.g., any signal) with redundant RB" can be performed. The redundant RB can be referred to as a common RB. The terminal can select the redundant RB based on the position of the PSFCH transmission (e.g., actual PSFCH transmission).

[0221] In the embodiment of FIG. 19a, the PSFCH resource and the redundant RB can be set. In the frequency domain, the PSFCH resource (e.g., PSFCH resource region) can be set in units of two RBs, and the redundant RB can be set between the PSFCH resources. The PSFCH resource can be used for PSFCH transmission, and at least one of the redundant RBs can be used for the transmission of any signal. The redundant RB located within two RBs based on the PSFCH resource where the actual PSFCH transmission is performed may not be used for the transmission of any signal. The setting of the PSFCH resource and the redundant RB in the embodiment of FIG. 19a can be applied to the embodiments of FIGS. 19b and / or 19c.

[0222] In the embodiment of FIG. 19b, the actual PSFCH transmission can be performed with PSFCH resource #A. In this case, the redundant RB #X located within two RBs based on PSFCH resource #A may not be used for the transmission of any signal. In other words, the terminal can transmit any signal with the remaining redundant RBs excluding redundant RB #X.

[0223] In the embodiment of FIG. 19c, the actual PSFCH transmission can be performed on PSFCH resource #B. In this case, redundant RBs #Y and #Z located within two RBs based on PSFCH resource #B may not be used for the transmission of any signal. In other words, the terminal can transmit any signal on the remaining redundant RBs excluding redundant RBs #Y and #Z among the redundant RBs.

[0224] When redundant RBs for transmitting any signal are selected based on the position of the PSFCH resource where the actual PSFCH transmission is performed, the interference between the PSFCH transmission and the transmission of any signal can be reduced, and the unnecessary transmission power can be reduced. Therefore, the PSFCH transmission can be efficiently performed.

[0225] When both the transmission of any signal and the PSFCH transmission are performed in a set of redundant RBs having an interleaved structure, the PAPR may increase compared to the PAPR of the existing PSFCH transmission. In order to reduce the PAPR when both the transmission of any signal and the PSFCH transmission are performed in a set of redundant RBs having an interleaved structure, cyclic shift hopping on an RB unit can be applied. "When there is a PSFCH transmission section (for example, a PSFCH occasion) within the COT and the terminal does not transmit PSFCH in the PSFCH transmission section", the terminal may lose the COT. Even when the PSFCH transmission is unnecessary within the COT, the terminal can transmit any signal on the redundant RBs within the COT to maintain the COT. When the COT is maintained by the method, the resources can be efficiently used.

[0226] The number of dedicated RBs for actual PSFCH transmission (e.g., 1, 2, or 5) can be preset. The interval between common RBs (e.g., redundant RBs) and dedicated RBs in the frequency domain can be 1 MHz. The interval between common RBs and dedicated RBs can be preset. The above setting operation can be performed through signaling. The common RBs can have an interleaved structure. When the interval between common RBs and dedicated RBs in the frequency domain is below a threshold value, the terminal may not be able to transmit any signal on the common RBs. In this case, the terminal can perform PSFCH transmission on the dedicated RBs without transmitting any signal. When the interval between common RBs and dedicated RBs in the frequency domain exceeds the threshold value, the terminal can perform both the transmission of any signal on the common RBs and PSFCH transmission on the dedicated RBs. The transmission of any signal and PSFCH transmission can be multiplexed in the frequency domain. The above threshold value can be set for the terminal through signaling. The PSFCH transmission method can be classified as follows.

[0227] - PSFCH Transmission Method 1: The PSFCH format (e.g., PSFCH format 0) can have an interleaved structure, and the PSFCH format can be repeatedly transmitted in the frequency domain.

[0228] - PSFCH Transmission Method 2: Both PSFCH transmission on dedicated RBs and the transmission of any signal on common RBs can be performed.

[0229] Cyclic shift hopping can be applied in PSFCH Transmission Method 1 and / or 2. The PSFCH transmission method can be preset in resource pool or SL-BWP units. For example, PSFCH Transmission Method 1 for the first resource pool can be set through signaling, and PSFCH Transmission Method 2 for the second resource pool can be set through signaling.

[0230] For the transmission operations of other SL channels and / or signals (e.g., PSSCH, PSCCH) in addition to PSFCH in the unlicensed band, the requirement conditions of the LBT operation and / or the OCB regulations must be satisfied. PSSCH transmission can be performed to satisfy the OCB regulations. PSSCH resources can be set in an interleaved structure in the frequency domain. When the PSSCH resources have an interleaved structure to satisfy the OCB regulations, the terminal that receives PSSCH on the PSSCH resources can transmit PSFCH for the PSSCH on the resources corresponding to the PSSCH resources. In this case, the PSFCH transmission can satisfy the OCB regulations.

[0231] When the PSFCH transmission is performed within the COT, transmission collisions between terminals can be prevented. When the PSFCH transmission is required outside the COT, the PSFCH transmission can be performed based on the proposed method. The terminal can implicitly confirm the possibility of PSFCH transmission within the COT based on the PSSCH reception time, the PSFCH period, the transmission-related timeline, and / or the COT duration. As another method, information on the possibility of PSFCH transmission within the COT can be explicitly indicated to the terminal through signaling (e.g., a 1-bit indicator (e.g., COT indicator) included in the SCI).

[0232] When "multiple PSFCH occasions are not guaranteed and the LBT operation for PSFCH transmission fails" or "the LBT operation for PSFCH transmission fails and it is impossible to delay the PSFCH transmission to the next PSFCH resource", the terminal can transmit HARQ-ACK (for example, feedback information) through the SCI. In other words, the terminal can transmit an SCI including HARQ-ACK. The terminal can notify HARQ-ACK using a 1-bit indicator included in the SCI. The SCI can further include PSSCH information (for example, information for verifying the PSSCH) related to the HARQ-ACK indicated by the SCI. For example, the SCI including HARQ-ACK can include a TX ID and / or an RX ID for the PSSCH related to the HARQ-ACK. The TX ID of the PSSCH can be replaced by the TX ID or RX ID of an SCI (for example, an existing SCI, PSCCH). The RX ID of the PSSCH can be replaced by the RX ID or TX ID of an SCI (for example, an existing SCI, PSCCH). The SCI including HARQ-ACK can include information on the slot and / or subchannel (for example, the first subchannel) in which the PSSCH related to the HARQ-ACK was transmitted. The information on the slot can mean a slot index. The information on the subchannel can mean a subchannel index.

[0233] The SCI including HARQ-ACK can be a first-stage SCI or a second-stage SCI. The SCI including HARQ-ACK can include scheduling information for the PSSCH. In this case, the terminal can transmit an SCI including HARQ-ACK and scheduling information, and can transmit data on the PSSCH scheduled by the SCI. If there is no data, the terminal can transmit a dummy signal on the PSSCH scheduled by the SCI. Or if there is no data, the terminal may not be able to perform transmission on the PSSCH scheduled by the SCI.

[0234] For the distinction between the state in which data is transmitted on the PSSCH and the state in which a dummy signal is transmitted on the PSSCH, or for the distinction between the state in which data is transmitted on the PSSCH and the state in which transmission is not performed on the PSSCH, the SCI can include a specific field indicating a specific state. The first state indicated by the specific field included in the SCI may mean the state in which data is transmitted on the PSSCH. The second state indicated by the specific field included in the SCI may mean the state in which a dummy signal is transmitted on the PSSCH. The third state indicated by the specific field included in the SCI may mean the state in which transmission is not performed on the PSSCH.

[0235] Multiple RB sets need to be considered for PSCCH transmission, PSSCH transmission, and / or PSFCH transmission. Data can be transmitted through multiple RB sets having an interleaved structure. In this case, the SCI (for example, the SCI that schedules data transmission) can include a specific RB set index for PSFCH transmission. The transmitting terminal can transmit an SCI including scheduling information and a specific RB set index for PSFCH transmission to the receiving terminal. The transmitting terminal can transmit data to the receiving terminal based on the scheduling information included in the SCI. The receiving terminal can receive the SCI from the transmitting terminal and can confirm the scheduling information included in the SCI and the specific RB set index for PSFCH transmission.

[0236] The receiving terminal can receive data from the transmitting terminal based on the scheduling information included in the SCI. The receiving terminal can perform the LBT operation on the specific RB set indicated by the SCI for the PSFCH transmission of the data. If the LBT operation on the specific RB set is successful, the receiving terminal can perform the PSFCH transmission through the specific RB set. If the LBT operation on the specific RB set fails, the terminal cannot perform the PSFCH transmission. In this case, the SL performance may deteriorate. To solve the above problem, information indicating the performance of PSFCH transmission using a plurality of RB sets can be signaled. In the above signaling procedure, a plurality of RB sets among the entire RB set can be indicated by an RB set index and / or a bitmap. When the performance of PSFCH transmission using a plurality of RB sets is indicated, the terminal can perform the LBT operation on each of the plurality of RB sets, and can perform the PSFCH transmission on the RB set where the LBT operation is successful. If the LBT operation is successful on two or more RB sets, the terminal can repeatedly transmit the same PSFCH on two or more RB sets.

[0237] The operations of the method according to the embodiments of the present disclosure can be embodied in a computer-readable program or code on a computer-readable recording medium. The computer-readable recording medium includes all types of recording devices in which information readable by a computer system is stored. Also, the computer-readable recording medium can be distributed over a computer system connected to a network and the computer-readable program or code can be stored and executed in a distributed manner.

[0238] Also, the computer-readable recording medium can include a hardware device specially configured to store and execute program instructions, such as a ROM (read-only memory), a RAM (random access memory), a flash memory, etc. The program instructions can include not only machine language code generated by a compiler but also high-level language code that can be executed by a computer using an interpreter or the like.

[0239] Although some aspects of the present disclosure have been described in the context of apparatuses, it can also be described by corresponding methods, where a block or apparatus corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method can also be shown by corresponding blocks or items or features of a corresponding apparatus. Some or all of the method steps can be performed (or utilized) by a hardware apparatus such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, at least one or more of the most important method steps can be performed by such an apparatus.

[0240] In an embodiment, a programmable logic device (for example, a field-programmable gate array) can be used to perform some or all of the functions of the method described herein. In an embodiment, a field-programmable gate array can operate together with a microprocessor for performing one of the methods described herein. Generally, it is preferred that the method be performed by some hardware apparatus.

[0241] Although the preferred embodiments of the present disclosure have been described above, it will be understood by those skilled in the relevant art that the present disclosure can be variously modified and changed without departing from the spirit and scope of the present disclosure described in the following claims.

Claims

1. A method for a first terminal, comprising: receiving side link control information (SCI) from a second terminal; receiving data scheduled by the SCI from the second terminal; generating a hybrid automatic repeat request - acknowledgement (HARQ - ACK) for the data; and performing a first listen - before - talk (LBT) operation for transmission of the HARQ - ACK at a first physical side link feedback channel (PSFCH) occasion among N PSFCH occasions set in the first terminal, wherein N is a natural number, the method for the first terminal.

2. The N PSFCH occasions include the first PSFCH occasion and N - 1 PSFCH occasions, and the first PSFCH occasion and the N - 1 PSFCH occasions are set by one message or independently set by different messages, the method for the first terminal according to Claim 1.

3. The SCI includes first information indicating whether the N PSFCH occasions are applicable. When the first information indicates that the N PSFCH occasions are applicable, the N PSFCH occasions are used for transmission of the HARQ - ACK. When the first information indicates that the N PSFCH occasions are not applicable, only the first PSFCH occasion is used for transmission of the HARQ - ACK, the method for the first terminal according to Claim 1.

4. When the first terminal cannot transmit the HARQ - ACK within channel occupancy time (COT), the N PSFCH occasions are used for transmission of the HARQ - ACK, the method for the first terminal according to Claim 1.

5. The method for the first terminal further includes: when the first LBT operation fails, performing a second LBT operation for transmission of the HARQ - ACK at a second PSFCH occasion among the N PSFCH occasions; and When the second LBT operation is successful, the method of the first terminal according to claim 1 further includes transmitting a PSFCH format including the HARQ-ACK to the second terminal at the second PSFCH occasion.

6. The method of the first terminal according to claim 5, wherein the PSFCH format is repeatedly transmitted in the frequency domain.

7. The method of the first terminal includes further including transmitting a first signal, transmission of the PSFCH format and transmission of the first signal are multiplexed in the frequency domain, transmission of the PSFCH format is performed on a dedicated RB (resource block) within the frequency domain, and transmission of the first signal is performed on a common RB within the frequency domain. The method of the first terminal according to claim 5.

8. The method of the first terminal according to claim 7, wherein transmission of the first signal on the common RB is performed when a frequency interval between the dedicated RB and the common RB exceeds a threshold value.

9. The method of the first terminal includes further including transmitting a first signal on a common RB to maintain COT. The method of the first terminal according to claim 1.

10. A method of a second terminal, comprising: transmitting SCI (sidelink control information) to a first terminal; transmitting data scheduled by the SCI to the first terminal; and performing a monitoring operation on one or more of N PSFCH (physical sidelink feedback channel) occasions set for the first terminal to receive a HARQ-ACK (hybrid automatic repeat request-acknowledgment) for the data, wherein N is a natural number. The method of the second terminal.

11. The method of the second terminal according to claim 10, wherein the N PSFCH occasions include the first PSFCH occasion and N-1 PSFCH occasions, and the first PSFCH occasion and the N-1 PSFCH occasions are set by one message or independently set by different messages.

12. The SCI includes first information indicating whether the N PSFCH occasions are applied. When the first information indicates that the N PSFCH occasions are applied, the N PSFCH occasions are used for the transmission of the HARQ-ACK. When the first information indicates that the N PSFCH occasions are not applied, only the first PSFCH occasion is used for the transmission of the HARQ-ACK. The method of the second terminal according to claim 10.

13. When the first terminal is unable to transmit the HARQ-ACK within the COT (channel occupancy time), the N PSFCH occasions are used for the transmission of the HARQ-ACK. The method of the second terminal according to claim 10.

14. The method of the second terminal further includes receiving, from the first terminal, a PSFCH format including the HARQ-ACK based on the monitoring operation. The method of the second terminal according to claim 10.

15. The PSFCH format is repeatedly received in the frequency domain or received in a dedicated RB (resource block) within the frequency domain. The method of the second terminal according to claim 14.

16. A first terminal, including a processor, wherein the processor causes the first terminal to receive SCI (sidelink control information) from a second terminal; receive data scheduled by the SCI from the second terminal; generate a HARQ-ACK (hybrid automatic repeat request-acknowledgment) for the data; and initiate a first LBT (listen before talk) operation for the transmission of the HARQ-ACK on the first PSFCH occasion among the N PSFCH (physical sidelink feedback channel) occasions set in the first terminal, wherein N is a natural number. The first terminal.

17. The SCI includes first information indicating whether the N PSFCH occasions are applied. When the first information indicates that the N PSFCH occasions are applied, the N PSFCH occasions are used for the transmission of the HARQ-ACK. When the first information indicates that the N PSFCH occasions are not applied, only the first PSFCH occasion is used for the transmission of the HARQ-ACK. The first terminal according to claim 16.

18. When the first terminal cannot transmit the HARQ-ACK within the COT (channel occupancy time), the N PSFCH occasions are used for the transmission of the HARQ-ACK. The first terminal according to claim 16.

19. The processor causes the first terminal to When the first LBT operation fails, perform a second LBT operation for the transmission of the HARQ-ACK with the second PSFCH occasion among the N PSFCH occasions; and When the second LBT operation is successful, further cause the second PSFCH occasion to transmit a PSFCH format including the HARQ-ACK to the second terminal. The first terminal according to claim 16.

20. The processor causes the first terminal to Further cause the transmission of a first signal, The transmission of the PSFCH format and the transmission of the first signal are multiplexed in the frequency domain. The transmission of the PSFCH format is performed with a dedicated RB (resource block) in the frequency domain, and the transmission of the first signal is performed with a common RB in the frequency domain. The first terminal according to claim 19.

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