Method and apparatus for sidelink communication in unlicensed frequency band

Abstract

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

Description

Technical Field

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

[0002] A communication system (e.g., a new radio (NR) communication system) utilizing a higher frequency band (e.g., a frequency band of 6 GHz or higher) than that of a long term evolution (LTE) communication system (or LTE-A communication system) (e.g., a frequency band of 6 GHz or lower) is being considered to handle the soaring wireless data. The NR system can support not only a frequency band of 6 GHz or lower but also a frequency band of 6 GHz or higher, and can support various communication services and scenarios compared to the LTE system. In addition, requirements for the NR system may include enhanced mobile broadband (eMBB), ultra-reliable low latency communication (URLLC), and massive machine type communication (mMTC).

[0003] At the same time, side link (SL) communication can be performed in an unlicensed band. The first terminal can transmit data to the second terminal in the unlicensed band, and the second terminal can transmit a hybrid automatic repeat request confirmation (HARQ-ACK) of the data to the first terminal. In order to transmit HARQ-ACK in the unlicensed band, the second terminal can perform a listen-before-send (LBT) operation. If the LBT operation fails, the second terminal may not be able to transmit HARQ-ACK to the first terminal. In this case, since the reliability of the communication system is reduced, a method for solving the above problem is needed. Summary of the invention

[0004] Technical issues

[0005] The present disclosure provides a method and apparatus for sidelink communication in an unlicensed frequency band.

[0006] Technical Solution

[0007] According to a first exemplary embodiment of the present disclosure, a method for a first terminal to achieve the above-mentioned purpose may include: 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 acknowledgment (HARQ-ACK) of the data; and performing a listen-before-transmit (LBT) operation for transmitting HARQ-ACK in the first physical sidelink feedback channel (PSFCH) opportunity among N PSFCH opportunities configured in the first terminal, where N is a natural number.

[0008] The N PSFCH opportunities may include a first PSFCH opportunity and (N-1) PSFCH opportunities, and the first PSFCH opportunity and the (N-1) PSFCH opportunity may be configured by one message or independently configured by different messages.

[0009] The SCI may include first information indicating whether N PSFCH opportunities are applied. When the first information indicates that N PSFCH opportunities are applied, the N PSFCH opportunities can be used to transmit HARQ-ACK. When the first information indicates that N PSFCH opportunities are not applied, only the first PSFCH opportunity can be used to transmit HARQ-ACK.

[0010] When the first terminal cannot transmit ARQ-ACK within the channel occupancy time (COT), N PSFCH opportunities may be used to transmit HARQ-ACK.

[0011] The method may also include: in response to the failure of the first LBT operation, performing a second LBT operation in a second PSFCH opportunity among the N PSFCH opportunities for transmitting HARQ-ACK; and in response to the success of the second LBT operation, transmitting a PSFCH format including HARQ-ACK to the second terminal in the second PSFCH opportunity.

[0012] The PSFCH format can be retransmitted in the frequency domain.

[0013] The method may also include: transmitting a first signal, wherein transmitting a PSFCH format and transmitting the first signal may be multiplexed in the frequency domain, transmitting the PFSCH format may be performed in a dedicated resource block (RB) in the frequency domain, and transmitting the first signal may be performed in a common RB in the frequency domain.

[0014] When a frequency interval between the dedicated RB and the common RB exceeds a threshold, transmitting the first signal may be performed in the common RB.

[0015] The method may further include transmitting the first signal in the common RB to maintain the COT.

[0016] According to a second exemplary embodiment of the present disclosure, a method for a second terminal to achieve the above-mentioned purpose may include: transmitting sidelink control information (SCI) to a first terminal; transmitting data scheduled by the SCI to the first terminal; and performing a monitoring operation in one or more of N physical sidelink feedback channel (PSFCH) opportunities configured in the first terminal to receive a hybrid automatic repeat request acknowledgment (HARQ-ACK) of the data, where N is a natural number.

[0017] The N PSFCH opportunities may include a first PSFCH opportunity and (N-1) PSFCH opportunities, and the first PSFCH opportunity and the (N-1) PSCCH opportunities may be configured by one message or independently configured by different messages.

[0018] The SCI may include first information indicating whether N PSFCH opportunities are applied. When the first information indicates that N PSFCH opportunities are applied, the N PSFCH opportunities can be used to transmit HARQ-ACK. When the first information indicates that N PSFCH opportunities are not applied, only the first PSFCH opportunity can be used to transmit HARQ-ACK.

[0019] When the first terminal cannot transmit ARQ-ACK within the channel occupancy time (COT), N PSFCH opportunities may be used to transmit HARQ-ACK.

[0020] The method may further include: receiving a PSFCH format including a HARQ-ACK from the first terminal based on the monitoring operation.

[0021] The PSFCH format may be received repeatedly in the frequency domain or may be received in a dedicated resource block (RB) in the frequency domain.

[0022] According to a third exemplary embodiment of the present disclosure, in order to achieve the above-mentioned purpose, the first terminal may include a processor, and the processor may enable the first terminal to execute: receiving side link control information (SCI) from the second terminal; receiving data scheduled by the SCI from the second terminal; generating a hybrid automatic repeat request acknowledgment (HARQ-ACK) of the data; and performing a listen-before-transmit (LBT) operation for transmitting HARQ-ACK in the first PSFCH opportunity among N physical sidelink feedback channel (PSFCH) opportunities configured in the first terminal, where N is a natural number.

[0023] The SCI may include first information indicating whether N PSFCH opportunities are applied, when the first information indicates that N PSFCH opportunities are applied, the N PSFCH opportunities can be used to transmit HARQ-ACK, and when the first information indicates that N PSFCH opportunities are not applied, only the first PSFCH opportunity can be used to transmit HARQ-ACK.

[0024] When the first terminal cannot transmit ARQ-ACK within the channel occupancy time (COT), N PSFCH opportunities may be used to transmit HARQ-ACK.

[0025] The processor can further cause the first terminal to execute: in response to the failure of the first LBT operation, perform a second LBT operation for transmitting HARQ-ACK at a second PSFCH opportunity among N PSFCH opportunities; and in response to the success of the second LBT operation, transmit a PSFCH format including HARQ-ACK to the second terminal at the second PSFCH opportunity.

[0026] The processor may further cause the first terminal to transmit a first signal, wherein transmitting a PSFCH format and transmitting the first signal may be multiplexed in the frequency domain, transmitting the PSFCH format may be performed in a dedicated resource block (RB) in the frequency domain, and transmitting the first signal may be performed in a common RB in the frequency domain.

[0027] Beneficial Effects

[0028] According to the present disclosure, multiple PSFCH opportunities can be configured. The terminal can perform a first LBT operation to perform PSFCH transmission in a first PSFCH opportunity among multiple PSFCH opportunities. If the first LBT operation fails, the terminal can perform a second LBT operation to perform PSFCH transmission in a second PSFCH opportunity among multiple PSFCH opportunities. According to the above method, since multiple LBT operations can be performed on PSFCH transmission, PSFCH transmission can be guaranteed.

[0029] The PSFCH format can be retransmitted in the frequency domain. Transmitting the PSFCH format and transmitting any signal can be multiplexed in the frequency domain. According to the above method, the occupied channel bandwidth (OCB) regulation can be met. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a conceptual diagram illustrating a first exemplary embodiment of a communication system.

[0031] Figure 2 is a block diagram showing a first exemplary embodiment of a communication node constituting a communication system.

[0032] Figure 3 is a conceptual diagram illustrating a first exemplary embodiment of a type 1 frame.

[0033] Figure 4 is a conceptual diagram illustrating a first exemplary embodiment of a type 2 frame.

[0034] Figure 5 is a conceptual diagram illustrating a first exemplary embodiment of a transmission method of an SS / PBCH block in a communication system.

[0035] Figure 6 is a conceptual diagram illustrating a first exemplary embodiment of an SS / PBCH block in a communication system.

[0036] Figure 7 is a conceptual diagram illustrating a second exemplary embodiment of a method of transmitting an SS / PBCH block in a communication system.

[0037] Figure 8 is a conceptual diagram showing a first exemplary embodiment of an SSB burst configuration.

[0038] Figure 9a is a conceptual diagram showing RMSI CORESET mapping mode #1 in a communication system.

[0039] Figure 9b is a conceptual diagram showing RMSI CORESET mapping mode #2 in a communication system.

[0040] Fig.9c is a conceptual diagram showing RMSI CORESET mapping mode #3 in a communication system.

[0041] Fig.10 is a conceptual diagram showing a first exemplary embodiment of a configuration of a slot in which a PSFCH is configured.

[0042] Fig.11 is a conceptual diagram showing a first exemplary embodiment of a PSFCH for ACK / NACK transmission.

[0043] Fig.12 is a conceptual diagram illustrating an exemplary embodiment of a method for multiplexing a control channel and a data channel in sidelink communication.

[0044] Fig.13 is a conceptual diagram illustrating a first exemplary embodiment of a resource selection operation.

[0045] Fig.14 is a conceptual diagram illustrating a first exemplary embodiment of a resource reselection operation.

[0046] Fig.15a is a conceptual diagram illustrating a first exemplary embodiment of AGC symbols for FDM SL transmission in multiple RB sets.

[0047] Fig.15b is a conceptual diagram illustrating a second exemplary embodiment of AGC symbols for FDM SL transmission in multiple RB sets.

[0048] Fig.16 is a conceptual diagram illustrating a first exemplary embodiment of a method for transmitting a PSFCH within a COT.

[0049] Fig.17a is a conceptual diagram showing a first exemplary embodiment of a resource configuration method for multiple PSFCH opportunities.

[0050] Fig.17b is a conceptual diagram illustrating a second exemplary embodiment of a resource configuration method for multiple PSFCH opportunities.

[0051] Fig.18a is a conceptual diagram showing a first exemplary embodiment of a PSFCH transmission method.

[0052] Fig.18b is a conceptual diagram showing a second exemplary embodiment of a PSFCH transmission method.

[0053] Fig.19a is a conceptual diagram illustrating a first exemplary embodiment of PSFCH transmission with redundant RBs.

[0054] Fig.19b is a conceptual diagram illustrating a second exemplary embodiment of PSFCH transmission with redundant RBs.

[0055] Fig.19c is a conceptual diagram illustrating a third exemplary embodiment of PSFCH transmission with redundant RBs. DETAILED DESCRIPTION

[0056] Exemplary embodiments of the present disclosure are disclosed herein. However, the specific structural and functional details disclosed herein are merely intended to describe the purposes of the embodiments of the present disclosure. Therefore, the embodiments of the present disclosure may be embodied in many alternative forms and should not be construed as being limited to the embodiments of the present disclosure set forth herein.

[0057] Therefore, although the present disclosure is capable of various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will be described in detail herein. However, it should be understood that it is not intended to limit the present disclosure to the specific forms disclosed, but rather, the present disclosure is intended to cover all modifications, equivalents and alternatives that fall within the spirit and scope of the present disclosure. Throughout the description of the drawings, the same reference numerals refer to the same elements.

[0058] It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. As used herein, the term "and / or" includes any and all combinations of one or more related listed items.

[0059] In exemplary embodiments of the present disclosure, “at least one of A and B” may refer to “at least one of A or B” or “at least one combination of one or more of A and B”. Furthermore, in exemplary embodiments of the present disclosure, “one or more of A and B” may refer to “one or more of A or B” or “one or more combinations of one or more of A and B”.

[0060] In exemplary embodiments of the present disclosure, "(re)transmission" may refer to "transmission", "retransmission" or "transmission and retransmission", "(re)configuration" may refer to "configuration", "reconfiguration" or "configuration and reconfiguration", "(re)connection" may refer to "connection", "reconnection" or "connection and reconnection", and "reaccess" may refer to "access", "reaccess" or "access and reaccess".

[0061] It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or there can be intervening elements. Conversely, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements. Other words used to describe the relationship between elements should be interpreted in a similar manner (i.e., "between" versus "directly between," "adjacent to" versus "directly adjacent to," etc.).

[0062] The terms used herein are only used to describe specific embodiments and are not intended to limit the present disclosure. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "the" used herein are intended to include plural forms. It should also be understood that when used herein, the terms "comprising", "comprising", "including" and / or "including" specify the presence of the features, values, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, values, steps, operations, elements, components and / or groups thereof.

[0063] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the present disclosure belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and unless explicitly defined herein, are not interpreted in an idealized or overly formal sense.

[0064] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. In order to facilitate overall understanding when describing the present disclosure, the same components in the drawings are denoted by the same reference numerals, and repeated descriptions thereof will be omitted.

[0065] A communication system to which an exemplary embodiment according to the present disclosure is applied will be described. The communication system may be a 4G communication system (e.g., a long term evolution (LTE) communication system or an LTE-A communication system), a 5G communication system (e.g., a new radio (NR) communication system), or a sixth generation (6G) communication system, etc. The 4G communication system may support communication in a frequency band of 6 GHz or lower, and the 5G communication system may support communication in a frequency band of 6 GHz or higher and a frequency band of 6 GHz or lower. The communication system to which the exemplary embodiment according to the present disclosure is applied is not limited to the contents described below, and may be applied to various communication systems according to the exemplary embodiment of the present disclosure. Here, the communication system may be used in the same sense as a communication network, and "LTE" may refer to a "4G communication system", "LTE communication system" or "LTE-A communication system", and "NR" may refer to a "5G communication system" or "NR communication system".

[0066] In an exemplary embodiment, “an operation (e.g., transmitting an operation) is configured” may mean “transmitting configuration information (e.g., an information element or parameter) for the operation and / or information indicating the execution of the operation by signaling”. “An information element (e.g., a parameter) is configured” may mean “used to signal the corresponding information element”. The signaling may be at least one of: system information (SI) signaling (e.g., transmitting a system information block (SIB) and / or a master information block (MIB)), RRC signaling (e.g., transmitting RRC parameters and / or higher layer parameters), MAC control element (CE) signaling, or PHY signaling (e.g., transmitting downlink control information (DCI), uplink control information (UCI), and / or sidelink control information (SCI)).

[0067] In the following, even when a method (e.g., transmission or reception of a signal) performed at a first communication node in a communication node is described, a corresponding second communication node may also perform a method (e.g., reception or transmission of a signal) corresponding to the method performed at the first communication node. That is, when describing the operation of a terminal, a base station corresponding to the terminal may perform an operation corresponding to the operation of the terminal. Conversely, when describing the operation of a base station, a terminal corresponding to the base station may perform an operation corresponding to the operation of the base station. In addition, when describing the operation of a first terminal, a second terminal corresponding to the first terminal may perform an operation corresponding to the operation of the first terminal. Conversely, when describing the operation of a second terminal, a first terminal corresponding to the second terminal may perform an operation corresponding to the operation of the second terminal.

[0068] Figure 1 is a conceptual diagram illustrating a first exemplary embodiment of a communication system.

[0069] See also Figure 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, and 130-6. In addition, the communication system 100 may further include a core network (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), and a mobility management entity (MME)). When the communication system 100 is a 5G communication system (e.g., a new radio (NR) system), the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), and the like.

[0070] The plurality of communication nodes 110 to 130 may support a communication protocol defined by the third generation partnership project (3GPP) specification (e.g., LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.). The plurality of communication nodes 110 to 130 may support code division multiple access (CDMA) technology, wideband CDMA (WCDMA) technology, time division multiple access (TDMA) technology, frequency division multiple access (FDMA) technology, orthogonal frequency division multiplexing (OFDM) technology, filtered OFDM technology, cyclic prefix OFDM (CP-OFDM) technology, discrete Fourier transform spread OFDM (DFT-s-OFDM) technology, orthogonal frequency division multiple access (OFDMA) technology, single carrier FDMA (SC-FDMA) technology, non-orthogonal multiple access (NOMA) technology, generalized frequency division multiplexing (GFDM) technology, filter band multi-carrier (FBMC) technology, universal filter multi-carrier (UFMC) technology, space division multiple access (SDMA) technology, etc. Each of the plurality of communication nodes may have the following structure.

[0071] Figure 2 is a block diagram showing a first exemplary embodiment of a communication node constituting a communication system.

[0072] See also Figure 2 , the communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 connected to a network for performing communication. In addition, the communication node 200 may 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 may communicate with each other when connected through a bus 270.

[0073] However, each component included in the communication node 200 may not be connected to the common bus 270, but may be connected to the processor 210 through a separate interface or a separate bus. 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 via a dedicated interface.

[0074] The processor 210 may execute a program stored in at least one of the memory 220 and the storage device 260. The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor, on which the method according to the embodiment of the present disclosure is executed. Each of the memory 220 and the storage device 260 may be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may include at least one of a read-only memory (ROM) and a random access memory (RAM).

[0075] See again Figure 1 , the communication system 100 may include a plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2, and a plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell, and each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the cell coverage of the first base station 110-1. In addition, the second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the cell coverage of the second base station 110-2. In addition, the fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5 and the sixth terminal 130-6 may belong to the cell coverage of the third base station 110-3. In addition, the first terminal 130-1 may belong to the cell coverage of the fourth base station 120-1, and the sixth terminal 130-6 may belong to the cell coverage of the fifth base station 120-2.

[0076] Here, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 may refer to a Node-B (NB), an evolved Node-B (eNB), a gNB, an advanced base station (ABS), a high reliability base station (HR-BS), a base transceiver station (BTS), a radio base station, a radio transceiver, an access point, an access node, a radio access station (RAS), a mobile multi-hop relay base station (MMR-BS), a relay station (RS), an advanced relay station (ARS), a high reliability relay station (HR-RS), a home NodeB (HNB), a home eNodeB (HeNB), a road side unit (RSU), a radio remote head (RRH), a transmission point (TP), a transmit and receive point (TRP), etc.

[0077] Each of the multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5 and 130-6 can refer to a user equipment (UE), a terminal equipment (TE), an advanced mobile station (AMS), a high reliability mobile station (HR-MS), a terminal, an access terminal, a mobile terminal, a station, a user station, a mobile station, a portable user station, a node, a device, an on-board unit (OBU), etc.

[0078] Each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in the same frequency band or in different frequency bands. The multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other via an ideal backhaul or a non-ideal backhaul, and exchange information with each other via an ideal or non-ideal backhaul. In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to a core network via an ideal or non-ideal backhaul. Each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can transmit the signal received from the core network to the corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5 or 130-6, and transmit the information received from the corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5 or 130-6 to the core network.

[0079] In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can support multiple-input multiple-output (MIMO) transmission (e.g., single-user MIMO (SU-MIMO), multi-user MIMO (MU-MIMO), massive MIMO, etc.), coordinated multi-point (CoMP) transmission, carrier aggregation (CA) transmission, transmission in unlicensed bands, device-to-device (D2D) communication (or proximity service (ProSe)), Internet of Things (IoT) communication, dual connectivity (DC), etc. Here, each of the multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5 and 130-6 can perform operations corresponding to the operations of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 (i.e., operations supported by the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2). For example, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 in SU-MIMO mode, and the fourth terminal 130-4 may receive a signal from the second base station 110-2 in SU-MIMO mode. Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 in MU-MIMO mode, and the fourth terminal 130-4 and the fifth terminal 130-5 may receive a signal from the second base station 110-2 in MU-MIMO mode.

[0080] The first base station 110-1, the second base station 110-2, and the third base station 110-3 can transmit signals to the fourth terminal 130-4 in a CoMP transmission manner, 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 in a CoMP manner. In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can exchange signals with the corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5, or 130-6 belonging to its cell coverage in a CA manner. Each of base stations 110-1, 110-2, and 110-3 may control D2D communication between the fourth terminal 130-4 and the fifth terminal 130-5, and thus the fourth terminal 130-4 and the fifth terminal 130-5 may perform D2D communication under the control of the second base station 110-2 and the third base station 110-3.

[0081] In addition, the communication system can support three types of frame structures. Type 1 frame structure can be applied to frequency division duplex (FDD) communication systems, type 2 frame structure can be applied to time division duplex (TDD) communication systems, and type 3 frame structure can be used for communication systems based on unlicensed frequency bands (e.g., licensed assisted access (LAA) communication systems).

[0082] Figure 3 is a conceptual diagram illustrating a first exemplary embodiment of a type 1 frame.

[0083] See also Figure 3 , the radio frame 300 may include 10 subframes, and a subframe may include 2 time slots. Therefore, the radio frame 300 may include 20 time slots (e.g., time slot #0, time slot #1, time slot #2, time slot #3, ..., time slot #18, and time slot #19). The length T of the radio frame 300 is f It can be 10 milliseconds (ms). The length of a subframe can be 1 ms, and the length of a time slot can be T slot It can be 0.5ms. Here, T s The sampling time may be indicated and may be 1 / 30720000s.

[0084] A time slot may consist of multiple OFDM symbols in the time domain or multiple resource blocks (RBs) in the frequency domain. An RB may consist of multiple subcarriers in the frequency domain. The number of OFDM symbols constituting a time slot may vary depending on the configuration of a cyclic prefix (CP). CP may be divided into a normal CP and an extended CP. If a normal CP is used, a time slot may consist of 7 OFDM symbols, in which case a subframe may consist of 14 OFDM symbols. If an extended CP is used, a time slot may consist of 6 OFDM symbols, in which case a subframe may consist of 12 OFDM symbols.

[0085] Figure 4 is a conceptual diagram illustrating a first exemplary embodiment of a type 2 frame.

[0086] See also Figure 4 , the radio frame 400 may include two half frames, and the half frame may include 5 subframes. Therefore, the radio frame 400 may include 10 subframes. The length T of the radio frame 400 f The length of a half frame can be 5 ms. The length of a subframe can be 1 ms. Here, T s It can be 1 / 30720000s.

[0087] The radio frame 400 may include at least one downlink subframe, at least one uplink subframe, and at least one special subframe. Each of the downlink subframe and the uplink subframe may include two time slots. The length of the time slot T slotIt can be 0.5ms. Among the subframes included in the radio frame 400, each of subframe #1 and subframe #6 can be a special subframe. For example, when the switching period between the downlink and the uplink is 5ms, the radio frame 400 can include 2 special subframes. Alternatively, the switching period between the downlink and the uplink is 10ms, and the 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.

[0088] The downlink pilot time slot can be regarded as a downlink interval and can be used for cell search, time and frequency synchronization acquisition of the terminal, channel estimation, etc. The protection period can be used to solve the interference problem of uplink data transmission caused by the delay of downlink data reception. In addition, the protection period can include the time required to switch from the downlink data reception operation to the uplink data transmission operation. The uplink pilot time slot can be used for uplink channel estimation, time and frequency synchronization acquisition, etc. The transmission of the physical random access channel (PRACH) or the sounding reference signal (SRS) can be performed in the uplink pilot time slot.

[0089] The lengths of the downlink pilot slot, the guard period, and the uplink pilot slot included in the special subframe may be variably adjusted as needed. In addition, the number and position of each of the downlink subframe, the uplink subframe, and the special subframe included in the radio frame 400 may be changed as needed.

[0090] In a communication system, a transmission time interval (TTI) may be a basic time unit for transmitting coded data through a physical layer. Short TTI may be used to support low latency requirements in a communication system. The length of a short TTI may be less than 1 ms. A conventional TTI with a length of 1 ms may be referred to as a basic TTI or a conventional TTI. In other words, a basic TTI may consist of one subframe. In order to support transmission based on a basic TTI, signals and channels may be configured based on subframes. For example, a cell-specific reference signal (CRS), a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH), etc. may be present in each subframe.

[0091] On the other hand, there may be one synchronization signal (e.g., a primary synchronization signal (PSS) and a secondary synchronization signal (SSS)) every 5 subframes, and there may be one physical broadcast channel (PBCH) every 10 subframes. In addition, each radio frame may be identified by an SFN, and the SFN may be used to define the transmission of signals longer than one radio frame (e.g., a paging signal, a reference signal for channel estimation, a signal for channel state information, etc.). The period of the SFN may be 1024.

[0092] In the LTE system, the PBCH may be a physical layer channel for transmitting system information, such as a master information block (MIB). The PBCH may be transmitted once every 10 subframes. That is, the transmission period of the PBCH may be 10ms, and the PBCH may be transmitted once in a radio frame. The same MIB may be transmitted during 4 consecutive radio frames, and after 4 consecutive radio frames, the MIB may be changed according to the situation of the LTE system. The transmission period for transmitting the same MIB may be referred to as a "PBCH TTI", and the PBCH TTI may be 40ms. That is, the MIB may be changed for each PBCH TTI.

[0093] The MIB may consist of 40 bits. Of the 40 bits constituting the MIB, 3 bits may be used to indicate the system frequency band, 3 bits may be used to indicate physical hybrid automatic repeat request (ARQ) indicator channel (PHICH) related information, 8 bits may be used to indicate the SFN, 10 bits may be configured as reserved bits, and 16 bits may be used for a cyclic redundancy check (CRC).

[0094] The SFN used to identify the radio frame may consist of a total of 10 bits (B9 to B0), and the most significant bits (MSB) 8 bits (B9 to B2) of the 10 bits may be indicated by the PBCH (ie, MIB). The MSB 8 bits (B9 to B2) of the SFN indicated by the PBCH (ie, MIB) may be the same during 4 consecutive radio frames (ie, PBCH TTI). The least significant bits (LSB) 2 bits (B1 to B0) of the SFN may change during 4 consecutive radio frames (ie, PBCH TTI) and may not be explicitly indicated by the PBCH (ie, MIB). The LSB (2 bits (B1 to B0)) of the SFN may be implicitly indicated by the scrambling sequence of the PBCH (hereinafter referred to as the "PBCH scrambling sequence").

[0095] The gold sequence generated by cell ID initialization can be used as a PBCH scrambling sequence, and the PBCH scrambling sequence can be initialized for every four consecutive radio frames (e.g., each PBCH TTI) based on the operation of "mod(SFN, 4)". The PBCH transmitted in the radio frame corresponding to the SFN with the LSB 2 bits (B1 to B0) set to "00" can be scrambled by the gold sequence generated by cell ID initialization. Thereafter, the gold sequence generated according to the operation of "mod(SFN, 4)" can be used to scramble the PBCH transmitted in the radio frame corresponding to the SFN with the LSB 2 bits (B1 to B0) set to "01", "10" and "11".

[0096] Therefore, the terminal that has acquired the cell ID during the initial cell search process can identify the value of the LSB 2 bits (B1 to B0) of the SFN (for example, "00", "01", "10" or "11") based on the PBCH scrambling sequence (ie, MIB) obtained during the decoding process of the PBCH. The terminal can use the LSB 2 bits (B1 to B0) of the SFN obtained based on the PBCH scrambling sequence and the MSB 8 bits (B9 to B2) in the SFN indicated by the PBCH (ie, MIB) to identify the SFN (ie, the entire bits B9 to B0 of the SFN).

[0097] On the other hand, the communication system can not only support high transmission rates, but also support the technical requirements of various service scenarios. For example, the communication system can support enhanced mobile broadband (eMBB) services, ultra-reliable low-latency communication (URLLC) services, massive machine type communication (mMTC) services, etc.

[0098] The subcarrier spacing of a communication system (e.g., an OFDM-based communication system) can be determined based on a carrier frequency offset (CFO), etc. CFO can be generated by a Doppler effect, a phase drift, etc., and can increase in proportion to the operating frequency. Therefore, in order to prevent the performance of the communication system from being degraded due to CFO, the subcarrier spacing can be increased in proportion to the operating frequency. On the other hand, as the subcarrier spacing increases, the CP overhead may increase. Therefore, the subcarrier spacing can be configured based on channel characteristics, radio frequency (RF) characteristics, etc. according to the frequency band.

[0099] The communication system may support the values ​​defined in Table 1 below.

[0100] [Table 1]

[0101]

[0102] For example, the subcarrier spacing of the communication system can be configured to be 15kHz, 30kHz, 60kHz, or 120kHz. The subcarrier spacing of the LTE system can be 15kHz, and the subcarrier spacing of the NR system can be 1, 2, 4, or 8 times the traditional subcarrier spacing of 15kHz. If the subcarrier spacing increases in units of powers of 2 of the traditional subcarrier spacing, the frame structure can be easily designed.

[0103] The communication system may support FR1 and FR2. FR2 may be divided into FR2-1 and FR2-2. FR1 may be a frequency band of 6 GHz or lower, FR2-1 may be a frequency band of 24.25 GHz to 52.6 GHz, and FR2-2 may be a frequency band of 52.6 GHz to 71 GHz. In an exemplary embodiment, FR2 may be FR2-1, FR2-1, or a frequency band including FR2-1 and FR2-2. In each of FR1, FR2-1, and FR2-2, the subcarrier spacing that may be used for data transmission may be defined as shown in Table 2 below. In each of FR1, FR2-1, and FR2-2, the SCS that may be used for synchronization signal block (SSB) transmission may be defined as shown in Table 3 below. In each of FR1, FR2-1, and FR2-2, the SCS that may be used for RACH transmission (e.g., Msg1 or Msg-A) may be defined as shown in Table 4 below.

[0104] [Table 2]

[0105]

[0106] [Table 3]

[0107]

[0108] [Table 4]

[0109]

[0110] The communication system may support a wide frequency band (e.g., hundreds of MHz to tens of GHz). Since the diffraction and reflection characteristics of radio waves are poor in the high frequency band, the propagation loss (e.g., path loss, reflection loss, etc.) in the high frequency band may be greater than the propagation loss in the low frequency band. Therefore, the cell coverage of the communication system supporting the high frequency band may be smaller than the cell coverage of the communication system supporting the low frequency band. In order to solve such a problem, a beamforming scheme based on multiple antenna elements can be used to increase the cell coverage in the communication system supporting the high frequency band.

[0111] The beamforming scheme may include a digital beamforming scheme, an analog beamforming scheme, a hybrid beamforming scheme, etc. In a communication system using a digital beamforming scheme, a plurality of RF paths may be used based on a digital precoder or a codebook to obtain beamforming gain. In a communication system using an analog beamforming scheme, an analog RF device (e.g., a phase shifter, a power amplifier (PA), a variable gain amplifier (VGA), etc.) and an antenna array may be used to obtain beamforming gain.

[0112] Since an expensive digital-to-analog converter (DAC) or analog-to-digital converter (ADC) is required for the digital beamforming scheme and a transceiver unit corresponding to the number of antenna elements, the complexity of the antenna implementation may increase to improve the beamforming gain. In the case of a communication system utilizing an analog beamforming scheme, since multiple antenna elements are connected to one transceiver unit through a phase shifter, the complexity of the antenna implementation may not increase significantly even if the beamforming gain increases. However, the beamforming performance of a communication system utilizing an analog beamforming scheme may be lower than that of a communication system utilizing a digital beamforming scheme. In addition, in a communication system utilizing an analog beamforming scheme, since the phase shifter is adjusted in the time domain, frequency resources may not be effectively utilized. Therefore, a hybrid beamforming scheme that is a combination of a digital scheme and an analog scheme may be utilized.

[0113] When the cell coverage is increased by utilizing a beamforming scheme, the common control channels and common signals (e.g., reference signals and synchronization signals) of all terminals belonging to the cell coverage and the control channels and data channels of each terminal can also be transmitted based on the beamforming scheme. In this case, the common control channels and common signals of all terminals belonging to the cell coverage can be transmitted based on a beam scanning scheme.

[0114] In addition, in the NR system, the synchronization signal / physical broadcast channel (SS / PBCH) block can also be transmitted in a beam scanning scheme. The SS / PBCH block can be composed of PSS, SSS, PBCH, etc. In the SS / PBCH block, PSS, SSS and PBCH can be configured in a time division multiplexing (TDM) manner. The SS / PBCH block may also be referred to as a "SS block (SSB)". One SS / PBCH block may be transmitted using N consecutive OFDM symbols. Here, N may be an integer equal to or greater than 4. The base station may periodically transmit the SS / PBCH block, and the terminal may acquire frequency / time synchronization, cell ID, system information, etc. based on the SS / PBCH block received from the base station. The SS / PBCH block may be transmitted as follows.

[0115] Figure 5 is a conceptual diagram illustrating a first exemplary embodiment of a transmission method of an SS / PBCH block in a communication system.

[0116] See also Figure 5 , one or more SS / PBCH blocks may be transmitted in a beam scanning scheme within an SS / PBCH block burst set. Up to L SS / PBCH blocks may be transmitted within one SS / PBCH block burst set. L may be an integer equal to or greater than 2 and may be defined in the 3GPP standard. L may vary depending on the region of the system frequency. Within an SS / PBCH block burst set, SS / PBCH blocks may be positioned continuously or distributedly. Continuous SS / PBCH blocks may be referred to as "SS / PBCH block bursts". An SS / PBCH block burst set may be repeated periodically, and the system information (e.g., MIB) transmitted by the PBCH of the SS / PBCH blocks within the SS / PBCH block burst set may be the same. The index of the SS / PBCH block, the index of the SS / PBCH block burst, the index of the OFDM symbol, the index of the time slot, etc. may be explicitly or implicitly indicated by the PBCH.

[0117] Figure 6 is a conceptual diagram illustrating a first exemplary embodiment of an SS / PBCH block in a communication system.

[0118] See also Figure 6 , signals and channels are arranged in an SS / PBCH block in the order of "PSS→PBCH→SSS→PBCH". PSS, SSS and PBCH within the SS / PBCH block can be configured in a TDM scheme. In the symbol where the SSS is located, the PBCH can be located in frequency resources above the SSS and in frequency resources below the SSS. That is, the PBCH can be transmitted in two end frequency bands adjacent to the frequency band in which the SSS is transmitted. When the maximum number of SS / PBCH blocks is 8 in a frequency band below 6 GHz, the SS / PBCH block index can be identified based on a demodulation reference signal (hereinafter referred to as "PBCH DMRS") for demodulating the PBCH. When the maximum number of SSBs is 64 in a frequency band above 6 GHz, the LSB 3 bits of the 6 bits representing the SS / PBCH block index can be identified based on the PBCH DMRS, and the remaining MSB 3 bits can be identified based on the payload of the PBCH.

[0119] The maximum system bandwidth that can be supported in the NR system can be 400MHz. The size of the maximum bandwidth that the terminal can support can vary according to the capabilities of the terminal. Therefore, the terminal can perform an initial access process (e.g., an initial connection process) by utilizing some system bandwidths of the NR system supporting broadband. In order to support the access process of terminals supporting various bandwidth sizes, the SS / PBCH blocks can be multiplexed in the frequency domain within the system bandwidth of the NR system supporting broadband. In this case, the SS / PBCH blocks can be transmitted as follows.

[0120] Figure 7 is a conceptual diagram illustrating a second exemplary embodiment of a method of transmitting an SS / PBCH block in a communication system.

[0121] See also Figure 7 , a wideband component carrier (CC) may include multiple bandwidth parts (BWPs). For example, a wideband CC may include 4 BWPs. The base station may transmit SS / PBCH blocks in corresponding BWPs #0 to #3 belonging to the wideband CC. The terminal may receive SS / PBCH blocks from one or more BWPs from BWPs #0 to #3, and may perform an initial access procedure using the received SS / PBCH blocks.

[0122] After detecting the SS / PBCH block, the terminal can acquire system information (e.g., remaining minimum system information (RMSI)), and can perform a cell access procedure based on the system information. RMSI can be transmitted on a PDSCH scheduled by a PDCCH. Configuration information of a control resource set (CORESET) can be transmitted on a PBCH within a SS / PBCH block, wherein the PDCCH includes scheduling information of a PDSCH transmitting RMSI. Multiple SS / PBCH blocks can be transmitted throughout the system frequency band, and one or more SS / PBCH blocks among the multiple SS / PBCH blocks can be SS / PBCH blocks associated with RMSI. The remaining SS / PBCH blocks may not be associated with RMSI. The SS / PBCH blocks associated with RMSI can be defined as "cell definition SS / PBCH blocks". The terminal can perform a cell search procedure and an initial access procedure by utilizing a cell definition SS / PBCH block. SS / PBCH blocks not associated with RMSI can be used for synchronization procedures and / or measurement procedures in corresponding BWPs. The BWP transmitting the SS / PBCH block can be limited to one or more BWPs within a wideband.

[0123] Depending on the values ​​of SCS and L, the position of SSB in time domain transmission can be defined differently. In an exemplary embodiment, SCS can represent the subcarrier size. SSB can be transmitted in some symbols within a time slot, and short UL transmission (e.g., uplink control information (UCI) transmission) can be performed in the remaining symbols not used for SSB transmission within a time slot. When SSB is transmitted in a radio resource to which a large SCS (e.g., 120kHz SCS or 240kHz SCS) is applied, a gap can be configured in the middle of consecutive time slots including SSB, so that long UL transmission (e.g., transmission of URLLC services) can be performed at least every 1ms.

[0124] Figure 8 is a conceptual diagram showing a first exemplary embodiment of an SSB burst configuration.

[0125] See also Figure 8 , during transmission of SSB (e.g., SSB burst) in radio resources to which 120kHz SCS is applied, the base station may transmit SSB in 8 consecutive time slots. During transmission of SSB in radio resources to which 240kHz SCS is applied, the base station may transmit SSB in 16 consecutive time slots. In radio resources to which 120kHz SCS or 240kHz SCS is applied, gaps for UL transmission may be configured.

[0126] The RMSI may be obtained by performing the following operations: an operation of obtaining configuration information of a CORESET from an SS / PBCH block (e.g., PBCH), an operation of detecting a PDCCH based on the CORESET configuration information, an operation of obtaining scheduling information of a PDSCH from a PDCCH, and an operation of receiving RMSI on a PDSCH. The transmission resources of the PDCCH may be configured by the configuration information of the CORESET. The mapping mode of the RMSI CORESET mode may be defined as follows. The RMSI CORESET may be a CORESET for transmission and reception of RMSI.

[0127] Figure 9a is a conceptual diagram showing RMSI CORESET mapping mode #1 in a communication system, Figure 9b is a conceptual diagram showing RMSI CORESET mapping mode #2 in a communication system, Fig.9c is a conceptual diagram showing RMSI CORESET mapping mode #3 in a communication system.

[0128] See also Figures 9a to 9c, one RMSI CORESET mapping mode among RMSI CORESET mapping modes #1 to #3 may be utilized, and a detailed configuration according to one RMSI CORESET mapping mode may be determined. In RMSI CORESET mapping mode #1, SS / PBCH blocks, CORESET (i.e., RMSI CORESET), and PDSCH (i.e., RMSIPDSCH) may be configured in a TDM scheme. RMSIPDSCH may refer to a PDSCH that transmits RMSI. In RMSI CORESET mapping mode #2, CORESET (i.e., RMSI CORESET) and PDSCH (i.e., RMSIPDSCH) may be configured in a TDM scheme, and PDSCH (i.e., RMSIPPDSCH) and SS / PBCH blocks may be configured in a frequency division multiplexing (FDM) scheme. In RMSI CORESET mapping mode #3, CORESET (ie, RMSI CORESET) and PDSCH (ie, RMSIPDSCH) may be configured in a TDM scheme, and CORESET (ie, RMSICORESET) and PDSCH (ie, RMSIPDSCH) may be multiplexed with SS / PBCH blocks in an FDM scheme.

[0129] In frequency bands of 6 GHz or lower, only RMSI CORESET mapping mode #1 can be utilized. In frequency bands of 6 GHz or higher, all RMSI CORESET mapping modes #1, #2, and #3 can be utilized. The values ​​of the SS / PBCH blocks may be different from the values ​​of RMSICORESET and RMSIPDSCH. Here, the values ​​may be the subcarrier spacing. In RMSI CORESET mapping mode #1, all combinations of values ​​may be utilized. In RMSI CORESET mapping mode #2, the value combination (120 kHz, 60 kHz) or (240 kHz, 120 kHz) may be used for SS / PBCH blocks and RMSI CORESET / PDSCH. In RMSI CORESET mapping mode #3, the value combination (120 kHz, 120 kHz) may be used for SS / PBCH blocks and RMSI CORESET / PDSCH.

[0130] According to the combination of the numerical value of the SS / PBCH block and the numerical value of the RMSI CORESET / PDSCH, an RMSI CORESET mapping mode can be selected from RMSI CORESET mapping modes #1 to #3. The configuration information of the RMSI CORESET may include Table A and Table B. Table A may indicate the number of resource blocks (RBs) of the RMSI CORESET, the number of symbols of the RMSI CORESET, and the offset between the RBs of the SS / PBCH block (e.g., the start RB or the end RB) and the RBs of the RMSI CORESET (e.g., the start RB or the end RB). Table B may indicate the number of search space sets per time slot, the offset of the RMSI CORESET, and the OFDM symbol index in each RMSI CORESET mapping mode. Table B may indicate information for configuring the monitoring timing of the RMSI PDCCH. Each of Table A and Table B may consist of multiple sub-tables. For example, Table A may include sub-tables 13-1 to 13-8 defined in Technical Specification (TS) 38.213, and Table B may include sub-tables 13-9 to 13-13 defined in TS 38.213. Each of Table A and Table B may be 4 bits in size.

[0131] In the NR system, PDSCH can be mapped to the time domain according to PDSCH mapping type A or PDSCH mapping type B. PDSCH mapping types A and B can be defined as shown in Table 5 below.

[0132] [Table 5]

[0133]

[0134] Type A (i.e., PDSCH mapping type A) may be a slot-based transmission. When using type A, the position of the start symbol of the PDSCH may be configured as one of {0, 1, 2, 3}. When using type A and a normal CP, the number of symbols constituting the PDSCH (e.g., the duration of the PDSCH) may be configured as one of 3 to 14 within a range not exceeding the slot boundary. Type B (i.e., PDSCH mapping type B) may be a non-slot-based transmission. When using type B, the position of the start symbol of the PDSCH may be configured as one of 0 to 12. When using type B and a normal CP, the number of symbols constituting the PDSCH (e.g., the duration of the PDSCH) may be configured as one of {2, 4, 7} within a range not exceeding the slot boundary. The ADMRS (hereinafter referred to as "PDSCH DMRS") used to demodulate the PDSCH (e.g., data) may be determined by a mapping type (e.g., type A or type B) and an ID indicating a length. The ID may be defined differently according to the PDSCH mapping type.

[0135] Meanwhile, the NR standardization meeting is discussing NR Unlicensed (NR-U). The NR-U system can increase network capacity by improving the utilization of limited frequency resources. The NR-U system can support operations in unlicensed frequency bands (e.g., unlicensed spectrum).

[0136] In the NR-U system, the terminal can determine whether to transmit a signal from the base station based on the discovery reference signal (DRS) received from the corresponding base station in the same manner as in the general NR system. In the NR-U system in independent (SA) mode, the terminal can acquire synchronization and / or system information based on DRS. In the NR-U system, DRS can be transmitted according to the provisions of the unlicensed frequency band (e.g., transmission frequency band, transmission power, transmission time, etc.). For example, according to the occupied channel bandwidth (OCB) provision, the signal can be configured and / or transmitted to occupy 80% of the total channel bandwidth (e.g., 20MHz).

[0137] In the NR-U system, a communication node (e.g., a base station, a terminal) may perform a listen-before-send (LBT) process before transmitting a signal and / or channel for coexistence with another system. The signal may be a synchronization signal, a reference signal (e.g., DRS, DMRS, channel state information (CSI)-RS, phase tracking (PT)-RS, sounding reference signal (SRS)), etc. The channel may be a downlink channel, an uplink channel, a side link channel, etc. In an exemplary embodiment, a signal may refer to a "signal", a "channel", or a "signal and a channel". The LBT process may be an operation for checking whether a signal is transmitted by another communication node. If the LBT process determines that there is no transmitted signal (e.g., when the LBT process is successful), the communication node may transmit the signal in an unlicensed band. If the LBT process determines that there is a transmitted signal (e.g., when the LBT fails), the communication node may not be able to transmit the signal in the unlicensed band. The communication node may perform an LBT process according to one of various categories before the signal is transmitted. The category of LBT may vary depending on the type of transmitted signal.

[0138] Meanwhile, the NR standardization meeting is discussing NR vehicle-to-everything (V2X) communication technology. NR V2X communication technology can be a technology based on device-to-device (D2D) communication technology to support communication between vehicles, between vehicles and infrastructure, and between vehicles and pedestrians. Technologies to reduce power consumption and improve reliability for NR V2C communication are being discussed.

[0139] NR V2X communication (e.g., side link communication) can be performed according to three transmission schemes (e.g., unicast scheme, broadcast scheme, multicast scheme). When using the unicast scheme, 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 refer to a paired logical connection between the source ID of the first terminal and the destination ID of the second terminal. The first terminal can transmit data (e.g., side link data) to the second terminal. When using the broadcast scheme, the first terminal can transmit data to all terminals. When using the multicast scheme, the first terminal can transmit data to a group consisting of multiple terminals (e.g., a multicast group). In SL communication (e.g., SL-U communication), the transmitting terminal can refer to a terminal that transmits data, and the receiving terminal can refer to a terminal that receives data.

[0140] When a unicast scheme is utilized, the second terminal may transmit feedback information (e.g., confirmation (ACK) or negative ACK (NACK)) to the first terminal in response to data received from the first terminal. In the following exemplary embodiments, the feedback information may be referred to as "HARQ-ACK", "feedback signal", "physical sidelink feedback channel (PSFCH) signal", etc. When ACK is received from the second terminal, the first terminal may determine that the data has been successfully received at the second terminal. When NACK is received from the second terminal, the first terminal may determine that the second terminal has failed to receive the data. In this case, the first terminal may transmit additional information to the second terminal based on the HARQ scheme. Alternatively, the first terminal may increase the probability of receiving the data at the second terminal by retransmitting the same data to the second terminal.

[0141] When a broadcast scheme is used, the process for transmitting feedback information of data may not be performed. For example, system information may be transmitted in a broadcast scheme, and the terminal may not transmit feedback information of the system information to the base station. Therefore, the base station may not be able to identify whether the system information has been successfully received at the terminal. To solve this problem, the base station may broadcast the system information periodically.

[0142] When a multicast scheme is utilized, the process of transmitting feedback information for data may not be performed. For example, necessary information may be periodically transmitted in a multicast scheme without the process of transmitting feedback information. However, when the number of terminal candidates participating in a communication based on a multicast scheme and / or the number of terminals participating in the communication is limited, and the data transmitted in the multicast scheme is data that should be received within a preconfigured time (e.g., data that is sensitive to delay), it may also be necessary to transmit feedback information in the multicast side link communication. The multicast side link communication may represent a side link communication performed in a multicast scheme. When the feedback information transmission process is performed in the multicast side link communication, data may be transmitted and received efficiently and reliably.

[0143] In multicast side link communication, two HARQ-ACK feedback schemes (i.e., the transmission process of feedback information) can be supported. When the number of receiving terminals in the side link group is large and service scenario 1 is supported, when data reception fails, some receiving terminals belonging to a specific range in the side link group can transmit NACK through PSFCH. The scheme can be multicast HARQ-ACK feedback option 1. In service scenario 1, some receiving terminals belonging to a specific range can be allowed to perform reception in a best-effort manner instead of all receiving terminals in the side link group. Service scenario 1 can be an extended sensor scenario, in which some receiving terminals belonging to a specific range need to receive the same sensor information from the transmitting terminal. In an exemplary embodiment, a transmitting terminal may refer to a terminal that transmits data, and a receiving terminal may refer to a terminal that receives data.

[0144] When the number of receiving terminals in the side link group is limited and service scenario 2 is supported, each of all receiving terminals belonging to the side link group can report HARQ-ACK of data separately through a separate PSFCH. This scheme can be multicast HARQ-ACK feedback option 2. In service scenario 2, since PSFCH resources are sufficient, the transmitting terminal can monitor the HARQ-ACK feedback of all receiving terminals belonging to the side link group, and data reception of all receiving terminals belonging to the side link group can be guaranteed.

[0145] As with the broadcast side link communication, in the unicast side link communication and the multicast side link communication, data can be transmitted and received without the HARQ-ACK feedback process. In this case, in order to increase the probability of receiving data, the transmitting terminal can retransmit the data a preset number of times.

[0146] In all transmission schemes (e.g., unicast transmission, multicast transmission, and broadcast transmission), the terminal can be statically or semi-statically configured whether to apply the HARQ-ACK feedback process 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 PSFCH. If the reception of PSSCH is successful, the receiving terminal can transmit the ACK (e.g., data) of PSSCH on PSSCH. If the reception of PSSCH fails, the receiving terminal can transmit the NACK (e.g., data) of PSSCH on PSFCH. PSFCH can be a channel for reporting ACK / NACK information (e.g., HARQ-ACK feedback) to the transmitting terminal. The resource area (e.g., PSFCH resource area) used for PSFCH transmission (e.g., transmission of HARQ-ACK feedback) can be pre-configured within a specific resource pool. PSFCH (e.g., PSFCH resources or PSFCH resource areas) can be periodically configured. The PSFCH period of the PSFCH resource may be k time slots (eg, logical side link (SL) time slots). k may be a natural number. For example, k may be 1, 2, or 4.

[0147] Fig.10 is a conceptual diagram showing a first exemplary embodiment of a configuration of a slot in which a PSFCH is configured.

[0148] See also Fig.10 , PSFCH (e.g., HARQ-ACK feedback) can be retransmitted in two symbols (e.g., two OFDM symbols) within a time slot (e.g., SL time slot). The first of the two symbols transmitting the PSFCH can be used for automatic gain control (AGC) to adjust the correct PSFCH reception power level.

[0149] The PSFCH may be transmitted within a frequency resource region preconfigured by system information. In this case, the frequency resource region used for PSFCH transmission may be indicated (e.g., signaled) in the form of a bitmap within a resource pool. The receiving terminal may implicitly select the location of the frequency resource region used for PSSCH transmission based on the index of the time slot and subchannel in which the PSSCH is received. The receiving terminal may identify the number of resource blocks (RBs) and the number of multiplexed PSFCH resources based on the cyclic shift of the PSFCH sequence within the frequency resource region. The receiving terminal may implicitly select the PSFCH index of the PSFCH resource based on the source identifier (ID) and the member ID. The source ID may be a physical layer source ID. The source ID may be the ID of the transmitting terminal that has transmitted the PSSCH.

[0150] The member ID may be used in the groupcast HARQ-ACK feedback option 2. When the groupcast HARQ-ACK feedback option 2 is applied, each of all receiving terminals in the group may transmit HARQ-ACK feedback of SL data separately through a separate PSFCH (e.g., PSFCH resource). In cases other than the above exemplary embodiments, the member ID may be set to 0.

[0151] Fig.11 is a conceptual diagram showing a first exemplary embodiment of a PSFCH for ACK / NACK transmission.

[0152] See also Fig.11 , the transmission time of PSFCH may be the first time slot (e.g., PSFCH time slot) in which PSFCH transmission can be performed after a preset time (e.g., sl-MinTimeGapPSFCH) from the reception time of the corresponding PSSCH. The PSFCH time slot may be a time slot in which PSFCH can be transmitted and / or a time slot in which PSFCH is configured. sl-MinTimeGapPSFCH may be set based on whether the reception of PSSCH is successful, taking into account the time required to process PSSCH after receiving PSSCH and the time required to prepare ACK / NACK (e.g., HARQ-ACK feedback). sl-MinTimeGapPSFCH may be set to 2 or 3 time slots. A terminal (e.g., a receiving terminal) may transmit PSFCH in time slot #n+12 (which is a time slot in which PSFCH transmission can be performed) after sl-MinTimeGapPSFCH (e.g., 3 time slots) from the reception time of PSSCH. n may be an integer greater than or equal to 0. In the present disclosure, the reception time may represent the reception start time and / or the reception end time, and the transmission time may represent the transmission start time and / or the transmission end time. The time may represent a moment and / or a duration.

[0153] By appropriately adjusting the transmission power of the transmitting terminal according to the transmission environment, the data reliability of the receiving terminal can be improved. By appropriately adjusting the transmission power of the transmitting terminal, the interference to other terminals can be reduced. Energy efficiency can be improved by reducing unnecessary transmission power. The power control scheme can be divided into an open-loop power control scheme and a closed-loop power control scheme. In the open-loop power control scheme, the transmitting terminal can determine the transmission power considering the configuration, the measured environment, etc. In the closed-loop power control scheme, the transmitting terminal can determine the transmission power based on the transmit power control (TPC) command received from the receiving terminal.

[0154] Due to various reasons including multipath fading channels, interference, etc., it may be difficult to predict the received signal strength at the receiving terminal. Therefore, the receiving terminal can adjust the received power level (e.g., received power range) by performing an automatic gain control (AGC) operation to prevent quantization errors of the received signal and maintain appropriate received power. In a communication system, the terminal can perform an 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. That is, in sidelink communication, communication between terminals can be performed without a base station. Therefore, it may be difficult to perform an AGC operation in a sidelink communication. In sidelink communication, the transmitting terminal may first transmit a signal (e.g., a reference signal) to the receiving terminal before transmitting data, and the receiving terminal may adjust the received power range (e.g., received power level) by performing an AGC operation based on the signal received from the transmitting terminal. Thereafter, the transmitting terminal may transmit sidelink data to the receiving terminal. The signal used for the AGC operation may be a signal copied from a signal to be transmitted later, or a signal pre-configured between terminals.

[0155] The time period required for ACG operation may be 15 μs. When a subcarrier spacing of 15 kHz is used in an NR system, the time period (e.g., length) of one symbol (e.g., OFDM symbol) may be 66.7 μs. When a subcarrier spacing of 30 kHz is used in an NR system, the time period of one symbol (e.g., OFDM symbol) may be 33.3 μs. In the following exemplary embodiments, a symbol may represent an OFDM symbol. That is, the time period of one symbol may be twice or more the time period required for ACG operation.

[0156] For sidelink communication, it may be necessary to transmit a data channel for data transmission and a control channel including scheduling information for data resource allocation. In sidelink communication, the data channel may be a physical sidelink shared channel (PSSCH) and the control channel may be a physical sidelink control channel (PSCCH). The data channel and the control channel may be multiplexed in a resource domain (e.g., a time and frequency resource domain).

[0157] Fig.12 is a conceptual diagram illustrating an exemplary embodiment of a method for multiplexing a control channel and a data channel in sidelink communication.

[0158] See also Fig.12, sidelink communication can support option 1A, option 1B, option 2, and option 3. When option 1A and / or option 1B are 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 domain and the frequency domain. Sidelink communication can basically support option 3.

[0159] In sidelink communication (e.g., NR-V2X sidelink communication), the basic unit of resource configuration may be a subchannel. A subchannel may be defined using time and frequency resources. For example, a subchannel may consist of multiple symbols (e.g., OFDM symbols) in the time domain and may consist of multiple resource blocks (RBs) in the frequency domain. A subchannel may be referred to as an RB set. In a subchannel, data channels and control channels may be multiplexed based on Option 3.

[0160] In sidelink communication (e.g., NR-V2X sidelink communication), transmission resources may be allocated based on mode 1 or mode 2. When using mode 1, the base station may allocate sidelink resources for data transmission to the transmitting terminal within the resource pool, and the transmitting terminal may transmit data to the receiving terminal using the sidelink resources allocated by the base station. Here, the transmitting terminal may be a terminal that transmits data in the sidelink communication, and the receiving terminal may be a terminal that receives data in the sidelink communication.

[0161] When using mode 2, the transmitting terminal can autonomously select the side link resource to be used for data transmission by performing resource sensing operations and / or resource selection operations in the resource pool. The base station can configure the resource pool for mode 1 and the resource pool for mode 2 to the terminal. The resource pool for mode 1 can be configured independently of the resource pool for mode 2. Alternatively, a common resource pool can be configured for mode 1 and mode 2.

[0162] When using mode 1, the base station can schedule resources for side link data transmission to the transmitting terminal, and the transmitting terminal can transmit the side link data to the receiving terminal by utilizing the resources scheduled by the base station. Therefore, resource conflicts between terminals can be prevented. When using mode 2, the transmitting terminal can select any resource by performing a resource sensing operation and / or a resource selection operation, and can transmit the side link data by utilizing any selected resource. Since the above process is performed based on a separate resource sensing operation and / or resource selection operation of each transmitting terminal, conflicts between the selected resources may occur.

[0163] Fig.13 is a conceptual diagram illustrating a first exemplary embodiment of a resource selection operation.

[0164] See also Fig.13, the terminal (e.g., the transmitting terminal) may perform a resource sensing operation within the sensing window, and may perform a resource selection operation on the resources sensed within the selection window (e.g., candidate resources). When the resource selection operation is triggered within time n, the terminal may select a resource based on the sensing result within the sensing window (e.g., from time n-T0 to time nT proc,0 time period) selects a suitable resource within a selection window (for example, within a time period from time n+T1 to time n+T2).

[0165] Based on the result of the resource sensing operation, the terminal can exclude candidate resources that do not meet the conditions within the selection window. In other words, the terminal can determine the remaining candidate resources other than inappropriate candidate resources from all candidate resources. When the ratio of the remaining candidate resources among all resources in 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 reference signal received power (RSRP) threshold (which is the condition for excluding candidate resources) by 3dB. Thereafter, the terminal can perform the resource selection operation again. For each priority level, the reference ratio can be preset to one of 20%, 35% or 50%. When the ratio of the remaining candidate resources is greater than or equal to the reference ratio, the terminal can randomly select the final resource for SL transmission from the remaining candidate resources. The terminal can use the final resource to perform SL transmission.

[0166] Fig.14 is a conceptual diagram illustrating a first exemplary embodiment of a resource reselection operation.

[0167] See also Fig.14 After the resource selection operation, the terminal may perform a resource reselection operation by considering non-periodic data transmission, etc. Fig.13 After the operation shown, the terminal may perform a resource reselection operation by additionally considering the perception result at time m-T3 before the actual SL transmission. The resource reselection operation may be performed within the reselection window. The terminal may also determine the suitability of the resources reserved at time m. When it is determined that the resources reserved at time m are suitable, the terminal may perform SL transmission using the reserved resources. When it is determined that the resources reserved at time m are not suitable, the terminal may reselect the resources for SL transmission and perform SL transmission using the reselected resources.

[0168] When an independent SL carrier is not configured for SL communication, some of the UL resources in the UL resources can be configured as SL resources through the SL resource pool configuration process. The bitmap can be repeatedly applied to the remaining time slots, excluding time slots that are not configured with at least X or more UL symbols within a specific time period and time slots that transmit side link (S)-SSB between time slots within a specific time period. X can be a natural number. The bitmap can indicate the time slots used as SL resources. For example, the time slots corresponding to the bits set to 1 in the bitmap can be used as SL resources.

[0169] It can be assumed that a 15kHz subcarrier spacing (SCS) is applied and X or more UL symbols are configured in all time slots. When there are 10240 available time slots in a direct frame number (DFN), the transmission period of S-SSB is 160ms, and there are 2 time slots for S-SSB transmission in each S-SSB transmission period, and the number of time slots used for S-SSB transmission in DFN can be 128. The bitmap for configuring SL time resources may include 10 bits. When a bitmap (e.g., a bitmap including 10 bits) is repeatedly applied to the remaining 10112 time slots other than the 128 time slots for S-SSB transmission in 10240 time slots, there may be two time slots (e.g., reserved time slots) to which the bitmap is not applied. It may be necessary to exclude these two reserved time slots. When these two reserved time slots are excluded from the 10112 time slots, 10110 time slots can be reserved. A bitmap (e.g., a bitmap including 10 bits) may be repeatedly applied 1011 times to 10110 time slots. When the bitmap is set to "1111000000" and the time slot corresponding to the bit set to 1 is used as an SL resource, 4044 time slots may be configured as SL resources within the DFN. In other words, by configuring the SL resource pool, 4044 time slots out of 10240 time slots may be used for SL communication.

[0170] A sidelink communication system supporting release version R-16 can be designed for terminals with no restrictions on battery capacity (e.g., vehicle-mounted terminals, vehicle UE (V-UE)). Therefore, energy saving may not be considered too much in the resource sensing / selection operation of such a terminal. However, in order to perform sidelink communication with terminals with limited battery capacity (e.g., terminals carried by pedestrians, terminals mounted on bicycles, terminals mounted on motorcycles, pedestrian UE (P-UE)) in a sidelink communication system supporting release version R-17, energy saving methods will be required. In the present disclosure, "V-UE" may refer to a terminal with no significant restrictions on battery capacity, and "P-UE" may refer to a terminal with limited battery capacity. "Resource sensing / selection operation" may refer to a resource sensing operation and / or a resource selection operation. A resource sensing operation may refer to a partial sensing operation or a full sensing operation. A resource selection operation may refer to a random selection operation. In addition, in the present disclosure, "terminal operation" may be interpreted as a "V-UE operation" and / or a "P-UE operation".

[0171] In order to save power in LTE V2X, partial sensing operation and / or random selection operation are introduced. When partial sensing operation is supported, the terminal can perform resource sensing operation in a partial period within the sensing window instead of the entire period, and can select resources based on the results of the partial sensing operation. According to such operation, the power consumption of the terminal can be reduced.

[0172] In the release version R-14 LTE V2X, only periodic data transmission operations and reception operations may be performed. In the release version R-14 LTE V2X, the terminal can arbitrarily select candidate time slots within a resource selection period (e.g., a selection window) considering a preset minimum number, and perform partial sensing operations considering a period of k×100ms. k can be signaled via a bitmap (e.g., a bitmap including 10 bits). k can be determined based on the position of the bits included in the bitmap. For example, the 10 bits included in the bitmap can correspond to values ​​1 to 10 in the MSB, respectively, 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.

[0173] When the MSB in the bitmap is set to 1, k may be 1. In this case, considering a period of 100ms (=1×100ms), the terminal may perform a partial sensing operation. When the bit adjacent to the MSB in the bitmap is set to 1, k may be 2. In this case, considering a period of 200ms (=2×100ms), the terminal may perform a partial sensing operation. When the LSB in the bitmap is set to 1, k may be 10. In this case, considering a period of 1000ms (=10×100ms), the terminal may perform a partial sensing operation.

[0174] In the release version R-14 LTE V2X, the period (e.g., the period of partial sensing operation) can be set to 20ms or 50ms. A period of 20ms or 50ms may not be supported in the resource pool of the P-UE. In the NR communication system, in addition to {0, 100ms, 200ms, ..., 1000ms}, shorter periods can also be supported. The short period can be {1ms, 2ms, ..., 99ms}. Up to 16 periods can be selected from the resource pool, and the selected period can be pre-configured to the terminal. The terminal can use one or more configured periods to perform resource sensing operations and / or resource (re) selection operations. When a random selection operation is supported, the terminal can randomly select resources without performing a resource sensing operation. Alternatively, the random selection operation can be performed together with the resource sensing operation. For example, the terminal can determine the resources by performing a resource sensing operation, and can select the resources by performing a random selection operation within the determined resources.

[0175] In LTE V2X supporting release version R-14, a resource pool that can perform partial sensing operations and / or random selection operations can be configured independently of a resource pool that can perform full sensing operations. A resource pool that can perform a random selection operation, a resource pool that can perform a partial sensing operation, and a resource pool that can perform a full sensing operation can be configured independently. In other words, a random selection operation, a partial sensing operation, or both a random selection operation and a partial sensing operation can be configured for each resource pool. When both a random selection operation and a partial sensing operation are configured for a resource pool, the terminal can select an operation from the random selection operation and the partial sensing operation, select resources by performing the selected operation, and perform SL communication using the selected resources.

[0176] In LTE V2X supporting release version R-14, side link (SL) data can be periodically transmitted based on a broadcast scheme. In an NR communication system, SL data can be transmitted based on a broadcast scheme, a multicast scheme, a groupcast scheme, or a unicast scheme. In addition, in an NR communication system, SL data can be transmitted periodically or non-periodically. The transmitting terminal can transmit SL data to the receiving terminal, and the receiving terminal can transmit HARQ feedback (e.g., acknowledgment (ACK) or negative ACK (NACK)) for the SL data to the transmitting terminal on the PSFCH. In the present disclosure, the transmitting terminal may refer to a terminal that transmits SL data, and the receiving terminal may refer to a terminal that receives SL data.

[0177] Terminals with reduced capacity (hereinafter referred to as "RedCap terminals") can operate in specific usage environments. The capacity of RedCap terminals may be lower than that of New Radio (NR) normal terminals, but may be higher than the capacity of LTE Machine Type Communication (LTE-MTC) terminals, narrowband (NB) Internet of Things (IoT) terminals, and low power wide area (LPWA) terminals. For example, there may be terminals that require high data rates and non-high latency conditions (e.g., surveillance cameras) and / or terminals that require non-high data rates, high latency conditions, and high reliability (e.g., wearable devices). In order to support the above terminals, the maximum carrier bandwidth in FR1 can be reduced from 100MHz to 20MHz, and the maximum carrier bandwidth in FR2 can be reduced from 400MHz to 100MHz. The number of receiving antennas of the RedCap terminal may be less than the number of receiving antennas of the NR normal terminal. When the carrier bandwidth and the number of receiving antennas are reduced, the reception performance of the RedCap terminal may be reduced, and therefore, the coverage of the RedCap terminal may be reduced.

[0178] A communication system (e.g., an NR system) may operate in a frequency band higher than the 52.6 GHz frequency band. As the frequency of the frequency band in which the communication system operates increases, frequency offset errors and phase noise may increase. In this environment, the use of a large SCS may be necessary for robust operation. In the FR2 band, 60 kHz SCS and / or 120 kHz SCS may be supported, and 480 kHz SCS and / or 960 kHz SCS may be additionally supported. In addition, physical layer signals and channels and physical layer processes may need to be designed according to the new SCS. Regarding the initial access process, 120 kHz SSB and / or 240 kHz SSB may be supported in the FR2 band, and 480 kHz SSB and / or 960 kHz SSB may be additionally supported. Here, 120 kHz SSB may refer to an SSB transmitted in a radio resource to which 120 kHz SCS is applied, and 240 kHz SSB may refer to an SSB transmitted in a radio resource to which 240 kHz SCS is applied. A method for configuring an initial BWP and an SSB burst set mode to support a new SCS may be required.

[0179] In Release R-18, carrier aggregation (CA) techniques for increasing the transmission rate of data on the side link, support for operation in unlicensed spectrum, performance improvement in FR2 licensed spectrum, and / or co-channel coexistence between LTE SL and NR SL may be discussed.

[0180] For sidelink (SL) communication in an unlicensed band (e.g., unlicensed spectrum), such as in an NR-U system, the transmission band, transmission power and / or transmission time shall comply with regulations according to the use of the unlicensed band. It may be necessary to design sidelink signals and / or channels applicable to the above regulations. In the present disclosure, SL communication in an unlicensed band may be referred to as "SL unlicensed (SL-U) communication". In the present disclosure, SL communication may refer to "SL-U communication", SL communication methods may be applied to SL-U communication, and NR-U communication methods may be applied to SL-U. In an existing SL system, one SL BWP may be configured, and SL communication may be performed based on multiple resource pools configured within one SL BWP. One SL BWP for SL-U communication may be configured, and SL-U communication may be performed based on multiple resource pools configured within one SL BWP.

[0181] Signal and / or channel transmission in SL-U communication should meet OCB regulations. It may be necessary to design SL channels (e.g., PSCCH, PSSCH and / or PSFCH) taking into account OCB regulations. In order to meet OCB regulations in NR-U communication, resource blocks (RBs) used for data transmission can be configured to have an interleaved (or interleaved) structure. When an interleaved structure (e.g., an interleaved RB structure) is utilized, the RBs can be configured to have regular intervals in the frequency domain. In this case, resource allocation for data transmission can be signaled by a combination of a starting interleaving index (e.g., a starting RB interleaving index) and an interleaving length. RBs may refer to physical resource blocks (PRBs).

[0182] In SL-U communication, the subchannel may be configured to have an interlaced RB structure. In this case, the provisions of OCB may be met. A subchannel including K interlaced subchannels may be configured. K may be a natural number greater than or equal to 1. K (e.g., the value of K) may be configured to the terminal via signaling (e.g., system information, PC5-RRC signaling, UE-specific RRC signaling and / or control information). K may be configured statically, semi-statically, or dynamically.

[0183] When a subchannel includes one interlace (e.g., one RB interlace) (e.g., when K is 1), the interlace index may be the same as the subchannel index. In this case, a separate interlace index may not be required. In the present disclosure, an interlace may represent an RB interlace. When a subchannel includes two or more interlaces (e.g., when K exceeds 1), the interlace index may be different from the subchannel index. In this case, a separate interlace index may be defined. An interlace may include one or more RBs. The RBs included in the interlace may have an interlaced structure.

[0184] In the unlicensed band, it is stipulated that it can be defined in units of 20MHz band. In the NR-U system, the RB corresponding to the 20MHz band can be defined as an RB set. A BWP may include multiple RB sets. When a communication node wants to transmit signals simultaneously using multiple RB sets in an unlicensed band, the channel access method for the transmission operation may be applied differently according to DL and UL. In NR-U DL communication, the base station may perform a type 1 channel access operation on each of multiple RB sets, and may perform transmission when the type 1 channel access operation is successful. The above process may be a type A channel access process. In NR-UDL communication, the base station may perform a type 1 channel access operation on one RB set in multiple RB sets, and may perform a sensing operation on the remaining RB sets within a minimum sensing period (e.g., 25us). When the type 1 channel access operation and the sensing operation are successful, the base station may perform a transmission operation. The above process may be a type B channel access process.

[0185] In NR-U UL communication, the terminal may perform a type 1 channel access operation in all channels of a plurality of channels, and when the type 1 channel access operation (e.g., LBT operation) succeeds in all channels of the plurality of channels, the terminal may transmit data. When the LBT operation fails in at least one channel of the plurality of channels, the terminal may not transmit data. The channel access procedure in NR-U UL communication may be used for general transmission in SL-U communication (e.g., PSCCH and / or PSSCH transmission). The channel access procedure in NR-U DL communication (e.g., type A or type B channel access) may be used for transmission of specific signals and / or channels (e.g., S-SSB and / or PSFCH transmission) in SL-U communication.

[0186] When multiple RB sets are configured, a protection band may be configured between RB sets in consideration of the operation in a single RB set. When there are multiple RB sets and the LBT operation is successful for some RB sets in the multiple RB sets, data may be transmitted in these RB sets. In this case, in order to improve resource efficiency, data transmission may be performed in resources including resources within the protection band between RB sets in which the LBT operation is successful. Information (e.g., control information) indicating whether data transmission is performed in resources within the protection band between RB sets may be transmitted by signaling.

[0187] A receiving node (e.g., a receiving terminal) can identify whether data transmission is performed in resources including resources within a protection band between RB sets by receiving control information. For the above-mentioned signaling operation, an RB set index for each of a plurality of RB sets can be configured. The control information can be transmitted on a control channel. The receiving node may not know in advance the RB sets in which the LBT operation is successful among the plurality of RB sets. Therefore, the receiving node can consider all possible combinations of a plurality of RB sets. In other words, the receiving node can perform a receiving operation based on all possible combinations. In this case, the complexity of the receiving node may increase. Unlike the transmission of the data channel, the transmission of the control channel may be limited to each RB set.

[0188] RB sets, type A channel access procedures in DL communications, type B channel access procedures in DL communications, and / or channel access procedures in UL communications may be applied to SL-U communications. It may be necessary to design channels (e.g., PSCCH, PSSCH, and / or PSFCH) in consideration of the above-mentioned procedures applied in SL-U communications. When channels and / or signals are transmitted through multiple RB sets in SL communications, the subchannel index may be configured as a combination of an interleaving index and an RB set index, and may be configured for each RB set. For example, one or more subchannels may be configured within RB set #0, and the indexes of one or more subchannels may be #0, #1, etc. One or more subchannels may be configured within RB set #1, and the indexes of one or more subchannels may be #0, #1, etc. Each RB set may include one or more interleavings, and subchannels belonging to each RB set may include one or more interleavings. The indexes of interleaved subchannels including the same index may be configured to be the same in the RB set. For example, the index of the subchannel including interlaces #0 and #1 in RB set #0 and the index of the subchannel including interlaces #0 and #1 in RB set #1 may be configured to be the same. When the PSSCH is transmitted through multiple subchannels, the PSCCH (e.g., the PSCCH scheduling the PSSCH) may be transmitted in a preconfigured resource region within the subchannel with the lowest index. The PSCCH scheduling the PSSCH may refer to the PSCCH associated with the PSSCH.

[0189] The time resources of the preconfigured resource area may include 2 or 3 symbols. The frequency resources of the preconfigured resource area may include 10, 12, 15, 20 or 25 RBs. When the channel and / or signal is transmitted through multiple RB sets and the subchannel has an interlaced RB structure, the PSSCH may be transmitted through the interlacing within the protection band between the RB sets, and the PSCCH (e.g., the PSCCH scheduling the PSSCH) may be transmitted through the preconfigured resource area within the interlacing corresponding to the subchannel with the lowest index. The PSCCH may not be transmitted through the interlacing within the protection band between the RB sets.

[0190] The subchannel with the lowest index in a specific RB set of multiple RB sets may overlap with the protection band between multiple RB sets. In this case, even when the subchannel overlapping the protection band between multiple RB sets is the subchannel with the lowest index in the specific RB set, the terminal may not transmit the PSCCH in the corresponding subchannel, but may transmit the PSCCH in the next subchannel (e.g., the subchannel with the next index). The PSCCH may be configured to be transmitted without interleaving within the protection band between RB sets. This configuration may be performed by signaling (e.g., system information, PC5-RRC signaling, UE-specific signaling, and / or SCI).

[0191] Taking into account the complexity of the terminal, resources can be configured so that the PSCCH is transmitted in one RB set (for example, the RB set with the lowest index). Specifically, the K interlaces included in the subchannel can be appropriately configured so that the resource area of ​​the PSCCH belongs to only one RB set. For example, when the number of RBs required for PSCCH transmission is 20, and the number of RBs included in one interlace within one RB set is less than 20, the subchannel may include two or more interlaces. In SL communication, control information can be divided into first-stage SCI and 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 in the protection band between the RB sets. In other words, the second-stage SCI can be mapped in the protection band between the RB sets, the transmission of the second-stage SCI may not be limited to one RB set, and the second-stage SCI can be transmitted in the same manner as the data.

[0192] As another method, when the second-stage SCI is transmitted on the PSSCH, the transmission of the second-stage SCI can be limited to one RB set. In other words, the second-stage SCI can be transmitted in the same manner as the first-stage SCI. In the case where the transmission of the second-stage SCI is limited to one RB set, the same or similar to multicast communication and / or broadcast communication, if the configuration of the RB sets between multiple terminals is different, the transmission of the second-stage SCI can be limited to a common resource area where the resource areas of all terminals overlap. In this case, information about the RB set in which the PSSCH is transmitted in multiple RB sets can be transmitted by SCI (e.g., the first-stage SCI and / or the second-stage SCI). The RB set used for PSSCH transmission can be indicated by the starting RB set and the number of RB sets (e.g., the number of consecutive RB sets), and the information about the starting RB set and the number of RB sets can be transmitted by signal. Alternatively, the RB set used for PSSCH transmission can be indicated by a bitmap, and the bitmap can be transmitted by signal.

[0193] As another method, PSCCH transmission for SL-U communication may be performed based on the same or similar method as PSCCH transmission in NR-U communication. PSCCH may be transmitted through a preconfigured RB set. PSCCH may be configured to be transmitted in some RB sets or all RB sets of multiple RB sets. In this case, the transmitting terminal may select an RB set in which the LBT operation is successful among the RB sets configured for PSCCH transmission, and may transmit PSCCH in the selected RB set. The receiving terminal may perform a PSCCH monitoring operation in the configured RB set. When the LBT operation is successful in multiple RB sets of the RB set configured for PSCCH transmission, the transmitting terminal may select an RB set from the multiple RB sets and transmit PSCCH in the selected one RB set. Alternatively, the transmitting terminal may transmit PSCCH in two or more RB sets or all RB sets of the multiple RB sets in which the LBT operation is successful. When PSCCH transmission is performed in multiple RB sets, the same information may be retransmitted.

[0194] In SL communication, a terminal may perform a sensing operation through SCI monitoring to determine whether other terminals utilize resources. When multiple RB sets are configured, some terminals may perform SL communication using one of the multiple RB sets. A first terminal that performs SL communication using multiple RB sets may transmit SCI (e.g., first-stage SCI and / or second-stage SCI) in a first RB set (e.g., an RB set with the lowest index), and a second terminal may perform a sensing operation in an RB set (e.g., a second RB set) other than the first RB set that transmits the SCI of the first terminal. 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. In this case, a data conflict may occur between the first terminal and the second terminal. For terminals that do not perform sensing operations in multiple RB sets, terminals that transmit data through multiple RB sets may retransmit SCI in all RB sets. In this case, the SCI may be transmitted through the lowest subchannel in the scheduling area of ​​each RB set.

[0195] 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 statically, semi-statically or dynamically. Taking into account various environments, the protection bands between RB sets can be configured in various ways. In SL unicast communication, the PC5-RRC connection establishment process between terminals can be performed in advance. During the PC5-RRC connection establishment process, the configuration information of multiple RB sets between terminals can be transmitted by signal. The number of RBs used for the protection band according to the configuration information of multiple RB sets of the first terminal may be different from the number of RBs used for the protection band according to the configuration information of multiple RB sets of the second terminal. In this case, the larger value of the number of RBs in the protection band of the first terminal and the number of RBs in the protection band of the second terminal can be applied. Here, the first terminal and the second terminal may be unicast terminals performing unicast communication.

[0196] In SL multicast communication, a multicast terminal may transmit configuration information of multiple RB sets. A multicast terminal may refer to a terminal that performs multicast transmission. All terminals in the group may perform communication based on the configuration information received from the multicast terminal. The number of RBs used for the protection band in multiple terminals in the group (e.g., the minimum number of RBs) may be different. In this case, the maximum value of the number of RBs used for the protection band in the group may be applied. In other words, the protection band may be configured considering the maximum number of RBs (e.g., the maximum value of the minimum number of RBs). For the above operation, the number of RBs used for the protection band (e.g., the minimum number of RBs) may be pre-shared between terminals in the group. In other words, the terminals in the group may know in advance the number of RBs used for the protection band of other terminals (e.g., the minimum number of RBs). When the number of RBs used for the protection band is not shared in the group, or when the terminals in the group do not know the number of RBs used for the protection band of another terminal, the maximum value of the number of RBs that can be configured for the protection band in the group may be applied. In other words, a protection band including the maximum number of RBs in the group may be configured.

[0197] In SL broadcast communication, the number of RBs used to protect the frequency band can be set to the maximum value of the configurable values. When the number of configurable RB sets in the first terminal is different from the number of configurable RB sets in the second terminal, multicast communication and / or broadcast communication can be performed in a common resource area where the resource areas of all terminals overlap. As another method, in SL multicast communication and SL broadcast communication, SL communication (e.g., SL multicast communication or SL broadcast communication) can be performed within one RB set, regardless of whether multiple RB sets are configured.

[0198] In order to ensure the number of attempts for LBT operation in SL-U communication, multiple starting points can be configured. The starting point may refer to the time point when data transmission starts, and the LBT operation for data transmission may be performed before the starting point. When data transmission is configured to start at the starting point of each time slot, if the LBT operation is unsuccessful before the starting point of each time slot, the terminal cannot start data transmission in the corresponding time slot. Multiple starting points (e.g., symbol #0 and symbol #X) can be configured for each time slot. X can be a natural number of 1 or greater. In this case, even if the LBT operation is unsuccessful before the first starting point of the time slot (e.g., symbol #0), the terminal can start data transmission if the LBT operation is successful before the next starting point of the time slot (e.g., symbol #X).

[0199] In order to ensure the number of attempts for LBT operation and / or improve resource efficiency, multiple starting points can be configured in the terminal. Since many starting points are configured, the number of attempts for LBT operation may increase and resource efficiency may be improved. However, when multiple starting points are configured, it may be necessary to consider each of the multiple starting points to redefine the calculation of the transport block (TB) size, PSCCH mapping, second-stage SCI mapping, DMRS mapping, etc. Therefore, the complexity of the communication system (e.g., SL-U system) may increase. In view of the above problems, it is preferably set an appropriate number of starting points. For example, two starting points are preferably configured.

[0200] The first of the two starting points may be symbol #0 or a symbol configured by sl-StartSymbol. In SL communication (e.g., SL-U communication), data transmission may be performed in a specific period starting from a specific symbol (e.g., a symbol configured by sl-StartSymbol) within a time slot instead of the entire time slot. The specific symbol may be configured as one of symbols #0 to #7. The specific period may include 7, 8, 9, 10, 11, 12, 13, or 14 symbols. The symbol configured by sl-StartSymbol may be a symbol other than symbol #0 (e.g., symbol #Y). Y may be a natural number of 1 or greater.

[0201] When the first starting point of SL communication (e.g., SL-U communication) is configured by sl-StartSymbol, the LBT operation can be performed considering the symbol configured by sl-StartSymbol. In this case, since at least one resource (e.g., channel) within symbols #0 to #Y may be pre-occupied by another system coexisting in the unlicensed band, it is preferred that the first starting point is always fixed 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 a transmission operation of an arbitrary signal or a transmission operation of a signal based on a cyclic prefix extension (CPE) in symbol #0, and can perform actual SL communication (e.g., SL-U communication) from the symbol configured by sl-StartSymbol.

[0202] Taking into account LBT operation (e.g., LBT scheme), the second of the two starting points can be appropriately configured within the time slot. For example, the second starting point can be configured in symbol #4 or after symbol #4. When data transmission is performed at the second starting point, it may be necessary to configure the DMRS mapping mode in consideration of the data transmission. In SL communication (e.g., SL-U communication), multiple DMR mapping modes according to multiple DMRSs can be configured by higher layer signaling. SCI can signal one of the multiple DMRS mapping modes for data transmission. The number of DMRSs can be configured according to the length of the PSSCH transmission. For example, the number of DMRSs can be set to 2, 3, or 4. The DMRS mapping mode in the time domain can be determined based on the length of the PSSCH transmission and / or the number of DMRSs. The length of the PSSCH transmission may refer to the length of the PSSCH. In other words, the length of the PSSCH transmission may represent the number of symbols used for PSSCH transmission scheduling.

[0203] The DMRS mapping mode can be configured considering multiple starting points. The DMRS mapping mode considering the first starting point (hereinafter referred to as the "first DMRS mapping mode") can be configured in the same manner as the existing DMRS mapping mode. The DMRS mapping mode considering the second starting point (hereinafter referred to as the "second DMRS mapping mode") can be configured separately. When the first DMRS mapping mode and the second DMRS mapping mode are configured independently, the number of first DMRS mapping modes may be different from the number of second DMR mapping modes. In this case, the number of bits used in the SCI to indicate the first DMRS mapping mode may be set differently from the number of bits used in the SCI to indicate the second DMRS mapping mode. For example, when the number of first DMRS mapping modes is 3 and the number of second DMRS mapping modes is 2, the number of bits required to indicate the first DMRS mapping mode may be 2, and the number of bits required to indicate the second DMR mapping mode may be 1.

[0204] When the DMRS mapping mode is independently configured according to the starting point, the overhead of the higher layer signaling used to configure the DMRS mapping mode may increase, and the number of bits used to indicate the DMRS mapping mode in the SCI may change. According to the above situation, the reception complexity of the terminal may increase. When the first DMRS mapping mode is configured, the second DMRS mapping mode can be implicitly indicated by the first DMRS mapping mode. For example, the number M of the second DMRS mapping modes may be less than or equal to the number N of the first DMRS mapping modes. Specifically, considering that the length of the PSSCH transmission is within the number N of the first DMRS mapping modes, the number M of the second DMRS mapping modes can be set to the maximum number.

[0205] The number of bits indicating one DMRS mapping mode (e.g., a DMRS mapping mode for PSSCH transmission) in the SCI may be determined based on N of the number N of the first DMRS mapping modes and the number M of the second DMRS mapping modes. For example, the number of bits indicating one DMRS mapping mode in the SCI may be log2(N). In this case, one of the first DMRS mapping modes may be indicated by log2(N) bits included in the SCI, and one of the second DMRS mapping modes may be indicated by log2(N) bits included in the SCI. In other words, the number of bits indicating one of the second DMRS mapping modes may be set equal to the number of bits indicating one of the first DMRS mapping modes.

[0206] [Table 6]

[0207]

[0208] Table 6 above can be used according to the PSSCH length l d The number of PSSCH DMRS and PSSCH DMRS indicates the DMRS mapping mode in the time domain. PSSCH DMRS can be a DMRS used to transmit and receive PSSCH. For example, when the first starting point is symbol #0, the PSSCH length l except the last guard symbol in the time slot d It may be a length corresponding to 13 symbols. When the PSCCH duration includes 2 symbols, the number of DMRSs may be 2, 3, or 4. In this case, the position of the symbol to which the DMRS is mapped (e.g., DMRS mapping mode) may be {3, 10}, {1, 6, 11}, or {1, 4, 7, 10}. The DMRS mapping mode may be indicated by two bits included in the SCI.

[0209] When the second starting point is symbol #4, the PSSCH length l except the last guard symbol in the slot dIt can be a length corresponding to 9 symbols. When the number of first DMRS mapping patterns is 3, the number of second DMRS mapping patterns can be determined as the maximum number (e.g., 2) within 3 (e.g., the number of first DMRS mapping patterns) without separate configuration. In other words, the number of first DMRS mapping patterns can be implicitly determined by considering the number of first DMRS mapping patterns. The signaling of the above operation can be performed by two bits for indicating the first DMRS mapping mode in the SCI. According to the above method, since separate signaling for indicating the second DMRS mapping mode is not required, the signaling overhead can be reduced. Since the number of bits indicating the DMRS mapping mode in the SCI does not change, the reception complexity of the terminal can be reduced.

[0210] When multiple starting points are configured in SL-U communication, a method for calculating the TB size taking into account the multiple starting points may be required. The TB size may be calculated based on the number of available resource elements (REs) and the modulation and coding scheme (MCS). When multiple starting points are configured, the number of available REs may vary depending on the location of the starting point. The reference number of symbols may be set so that the TB size is not confused between the transmitting terminal and the receiving terminal. The reference number of symbols for calculating the TB size may 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 through rate matching. In this case, the reception performance may deteriorate.

[0211] As another method, the number of reference symbols used to calculate the TB size may be defined based on the second starting point. When the TB size is calculated based on the second starting point, but actual data transmission is performed from the first starting point, many resources may be used for data transmission. In this case, some information (e.g., some data) may be additionally transmitted through rate matching. Therefore, reception performance may be improved, but resource efficiency may be reduced. In other words, since the transmitted TB is smaller than the calculated TB size, resource efficiency may be reduced.

[0212] As another method, a reference point for calculating the TB size can be configured for each resource pool through signaling (e.g., system information, RRC message). Depending on the situation of the communication system (e.g., SL system, SL-U system), the reference number of symbols for calculating the TB size can be determined based on the first starting point or the second starting point. For example, in an environment where many different services coexist, the success probability of the LBT operation may not be high. In this case, the reference number of symbols for calculating the TB size can be determined based on the second starting point. In a low-traffic environment, the success probability of the LBT operation may be very high. In this case, the reference number of symbols for calculating the TB size can be determined based on the first starting point.

[0213] As another method, a reference point for calculating the TB size may be dynamically signaled according to the time when the LBT operation of the transmitting terminal is successful. Specifically, the time when the data is transmitted according to the success of the LBT operation may be the first starting point or the second starting point, and the transmitting terminal may dynamically signal the reference point for calculating the TB size according to the time when the data is transmitted by using SCI (e.g., a 1-bit indicator included in the first stage SCI and / or the second stage SCI).

[0214] When multiple starting points are configured in SL-U communication, it may be necessary to design AGC symbols taking into account multiple starting points. For example, when multiple RB sets are configured within a resource pool (or BWP), SL transmission may be performed at different starting points within different RB sets. In this case, AGC problems may occur.

[0215] Fig.15a is a conceptual diagram showing a first exemplary embodiment of an AGC symbol for FDM SL transmission in a plurality of RB sets, Fig.15b is a conceptual diagram illustrating a second exemplary embodiment of AGC symbols for FDM SL transmission in multiple RB sets.

[0216] See also Fig.15a , AGC symbols can be configured at one starting point. SL TX#0 can be performed from the first starting point in RB set #0, and SL TX#1 can be performed from the second starting point in RB set #1. In this case, SL TX#1 may increase the received power, and therefore, SL TX#0 may have AGC problems (e.g., clipping). It can be proposed Fig.15b An exemplary embodiment of the present invention is used to solve the AGC problem.

[0217] See also Fig.15b , the AGC symbol can be configured at multiple starting points. In this case, even when SL TX#0 and SL TX#1 are performed, the AGC operation can be re-performed, so that the AGC problem does not occur. However, since the AGC symbol is difficult to use for data transmission, when the AGC symbol is configured at multiple starting points, the resource efficiency may be reduced and the reception complexity of the terminal may be increased. In order to solve the above problem, when a terminal performs SL transmission through multiple RB sets (e.g., all RB sets), it is preferred that even if multiple AGC symbols are configured, a terminal only uses one AGC symbol.

[0218] For example, when transmitting from the first starting point, the terminal may perform an AGC operation using a first AGC symbol (e.g., an AGC symbol configured at the first starting point), and may perform data transmission using a second AGC symbol (e.g., an AGC symbol configured at the second starting point). In other words, the terminal may transmit data without performing an AGC operation in the second AGC symbol. For another example, when transmitting from the second starting point, the terminal may perform an AGC operation using the second AGC symbol.

[0219] When only one RB set is configured in a resource pool (or BWP) and multiple AGC symbols are configured, it is preferred that the terminal uses one AGC symbol to perform the AGC operation. Multiple terminals can perform different SL transmissions (e.g., different SL-U transmissions) through multiple RB sets. In this case, if the terminal determines that the start positions of SL transmissions (e.g., SL-U transmissions) of other terminals are the same, the terminal can use only one AGC symbol even if multiple AGC symbols are configured.

[0220] PSFCH can be periodically configured within the SL resources (e.g., SL-U resources) configured in the above manner, such as Fig.10 and / or Fig.11 As shown in the exemplary embodiment. PSFCH can be a channel for HARQ-ACK (e.g., ACK or NACK) for transmitting data. Before the AGC operation and PSFCH transmission, there may be a protection symbol for switching between the transmission operation and the reception operation. The terminal can perform an LBT operation in the protection symbol for PSFCH transmission, and if the LBT operation fails, the PSFCH may not be transmitted. 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 it is identified that the data reception failure of the receiving terminal, the transmitting terminal can perform a data retransmission operation. PSFCH can be a channel that plays an important role in improving the reliability of SL communication. Preferably, PSFCH transmission in SL-U communication is guaranteed.

[0221] In NR-U communication, the time during which channels and / or signals can be transmitted due to the success of the LBT operation of the terminal or base station can be defined as the channel occupation time (COT). The transmission of channels and / or signals can be performed within the COT. The base station can initiate the COT and share the COT with the terminal. Alternatively, the terminal can initiate the COT and share the COT with the base station. The above operation can be referred to as "COT sharing". The terminal can transmit channels and / or signals within the COT shared by the base station without performing the LBT operation. Alternatively, the terminal can transmit channels and / or signals after performing the LBT operation within a short period of time of the COT shared by the base station. The base station can transmit channels and / or signals within the COT shared by the terminal without performing the LBT operation. Alternatively, the base station can transmit channels and / or signals after performing the LBT operation within a short period of time of the COT shared by the terminal. The LBT operation performed within a short period of time may be a type 2 LBT operation. The period for performing the type 2 LBT operation may be shorter than the period for performing the LBT operation (e.g., type 1 LBT operation) for ensuring the initial COT.

[0222] COT sharing can be introduced in SL-U communication. The first terminal can perform an LBT operation, can initiate a COT when the LBT operation is successful, and can share the COT with the second terminal. The second terminal can transmit SL channels and / or signals without performing an LBT operation within the COT shared by the first terminal. Alternatively, the second terminal can transmit SL channels and / or signals after performing a simplified LBT operation (e.g., a type 2 LBT operation) within the COT shared by the first terminal.

[0223] COT sharing can be applied to the SL data transmission process and / or the PSFCH transmission process. The first terminal can perform an LBT operation (e.g., a type 1 LBT operation) to transmit SL data to the second terminal, can ensure COT when the LBT operation is successful, and can transmit SL data to the second terminal within the COT. After transmitting SL data to the second terminal within the COT, the first terminal can share the remaining time period of the COT with the second terminal. In this case, the second terminal can receive SL data from the first terminal, and can transmit HARQ-ACK of SL data to the first terminal on the PSFCH within the remaining time period of the COT. PSFCH can be configured according to a specific period (e.g., 1, 2 or 4 logical time slots).

[0224] like Fig.11In an exemplary embodiment, a time offset for processing of a receiving terminal can be configured between data reception (e.g., PSSCH reception) and PSFCH transmission. The time offset can be configured by sl-MinTimeGapPSFCH. The time offset can be 2 or 3 logical time slots. Depending on the time offset, after receiving data from the first terminal, the second terminal may not be able to transmit HARQ-ACK for the data within the COT shared by the first terminal (e.g., the remaining period of the COT). In other words, if the difference between the PSSCH in the time domain and the PSFCH timing within the COT is less than the time offset, the second terminal may not be able to transmit the PSFCH within the COT.

[0225] Fig.16 is a conceptual diagram illustrating a first exemplary embodiment of a method for transmitting a PSFCH within a COT.

[0226] See also Fig.16 , the PSFCH period can be set to 4 time slots, and sl-MinTimeGapPSFCH can indicate 3 time slots. The first terminal can transmit PSSCH within the COT and can receive PSFCH of PSSCH. COT can be initiated by the first terminal. The first terminal can transmit PSSCH#0 to #5 to the second terminal within the COT. The second terminal can receive PSSCH#0 to #5 from the first terminal and can transmit PSFCH of PSSCH#0 to #5 to the first terminal. PSSCH#0 to #5 can be received by the same terminal or different terminals.

[0227] Considering sl-MinTimeGapPSFCH (e.g., 3 time slots), the PSFCH (e.g., PSFCH opportunity, PSFCH transmission opportunity, or PSFCH resource) corresponding to PSSCH #0, #1, and #2 can be located in time slot #n+12 within the COT initiated by the first terminal. Since the PSFCH is located within the COT, the second terminal can transmit the PSFCH to the first terminal in time slot #n+12 after performing a simplified LBT operation (e.g., type 2 LBT operation). In this case, reliable transmission of the PSFCH can be guaranteed.

[0228] Considering sl-MinTimeGapPSFCH (e.g., 3 slots), the PSFCH corresponding to PSSCH#3 to #5 can be located in slot #n+16. In other words, the PSFCH corresponding to PSSCH#3 to #5 can be located outside the COT initiated 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 if the new LBT operation fails, the PSFCH may not be transmitted. Considering the failure of the LBT operation, additional PSFCH opportunities can be configured.

[0229] The base station or the transmitting terminal may configure additional PSFCH opportunities to the terminal (e.g., the receiving terminal and / or the transmitting terminal) through signaling. For example, the base station or the transmitting terminal may transmit a message to the terminal (e.g., the receiving terminal and / or the transmitting terminal), the message including configuration information of the existing PSFCH opportunity and configuration information of the additional PSFCH opportunity. Or, for example, the base station or the transmitting terminal may transmit a first message to the terminal (e.g., the receiving terminal and / or the transmitting terminal), and may transmit a second message to the terminal (e.g., the receiving terminal and / or the transmitting terminal), the first message including configuration information of the existing PSFCH opportunity, and the second message including configuration information of the additional PSFCH opportunity. The first message and the second message may be independent messages.

[0230] An existing PSFCH transmission resource (e.g., an existing PSCCH opportunity) may be the PSFCH opportunity (i.e., the first PSFCH opportunity) that first occurs after the time slot indicated by sl-MinTimeGapPSFCH, starting from the reception time of the PSSCH. In SL-U communication, a maximum of N PSFCH opportunities may be configured. N may be a natural number. The N PSFCH opportunities may include the first PSFCH opportunity (e.g., an existing PSFCH opportunity). Alternatively, the N PSFCH opportunities may not include the first PSFCH opportunity (e.g., an existing PSFCH opportunity). In this case, one existing PSFCH opportunity and N additional PSFCH opportunities may be configured, and the total number of PSFCH opportunities may be N+1.

[0231] When PSFCH transmission fails in the first PSFCH opportunity, the terminal may attempt PSFCH transmission at the second PSFCH opportunity. The failure of PSFCH transmission may indicate the failure of the LBT operation of the PSFCH transmission. Alternatively, the failure of PSFCH transmission may indicate the failure of PSFCH transmission due to low priority or insufficient transmission power. When N PSFCH opportunities are configured, up to N LBT operations can be guaranteed to be performed. When N LBT operations fail, the terminal may abandon PSFCH transmission. According to the above method, reliable transmission of PSFCH can be guaranteed. N can be configured to the terminal through signaling (e.g., system information, PC5-RRC signaling and / or UE-specific RRC signaling). N can be configured statically or semi-statically. Alternatively, N can be dynamically configured by control information (e.g., DCI, SCI). N can be configured for each resource pool.

[0232] Up to N PSFCH opportunities can be applied to other PSFCH transmissions in addition to the PSFCH transmission for PSSCH within the COT. Up to one PSFCH opportunity can be configured for PSFCH transmission within the COT. The PSFCH cycle, the transmission-related timeline and / or the COT duration can be preconfigured. Therefore, the terminal can predetermine whether PSFCH transmission can be performed within the COT. Alternatively, information about whether PSFCH transmission can be performed within the COT can be transmitted by signaling (e.g., a 1-bit indicator). The terminal can identify the maximum number of PSFCH opportunities (e.g., 1 or N) for each PSFCH transmission based on the above method, and perform PSFCH transmission considering the maximum number of identified PSFCH opportunities.

[0233] As another approach, up to N PSFCH opportunities may be configured for all PSFCH transmissions, regardless of whether PSFCH transmission is possible within the COT. In this case, a PSFCH that cannot be transmitted due to failure of LBT operation and / or other reasons (e.g., PSFCH transmission according to priority is disconnected) may be transmittable. However, a terminal that expects to receive PSFCH may need to perform monitoring operations in N PSFCH opportunities. Therefore, the reception complexity of PSFCH may increase. Even if up to N PSFCH opportunities are guaranteed, the use of multiple PSFCH opportunities may be limited to specific situations.

[0234] For example, even if up to N PSFCH opportunities are guaranteed, multiple PSFCH opportunities can be configured to be used only in the event of a LBT operation failure. Even if up to N PSFCH opportunities are guaranteed, multiple PSFCH opportunities can be configured to be used only in the event of a PSFCH transmission drop. Even if up to N PSFCH opportunities are guaranteed, multiple PSFCH opportunities can be configured to be used only in the event of a PSFCH retransmission. The use of multiple PSFCH opportunities when up to N PSFCH opportunities are guaranteed can be configured by signaling (e.g., system information, PC5-RRC signaling, UE-specific RRC signaling, control information). The use of multiple PSCCH opportunities when up to N PSFCH opportunities are guaranteed can be configured statically, semi-statically, or dynamically. The use of multiple PSFCH opportunities when up to N PSFCH opportunities are guaranteed can be configured for each resource pool.

[0235] When multiple PSFCH opportunities are configured, the transmitting terminal may transmit to the receiving terminal an SCI including information indicating whether to utilize (e.g., whether to apply) multiple PSCCH opportunities. The SCI may also include scheduling information for the data. The receiving terminal may receive the SCI from the transmitting terminal, and may identify whether multiple PSFCH opportunities are utilized based on the information included in the SCI. When multiple PSFCH opportunities are not utilized, the receiving terminal may attempt to transmit HARQ-ACK (e.g., PSFCH format) to data received from the transmitting terminal in one PSFCH opportunity. When multiple PSFCH opportunities are utilized, the receiving terminal may attempt to transmit HARQ-ACK (e.g., PSFCH format) to data received from the transmitting terminal in multiple PSCCH opportunities.

[0236] When multiple PSFCH opportunities are configured, the PSFCH resource selection process can be newly defined. The terminal can select the PSSCH RB based on the position of the time slot and / or subchannel in which the PSSCH is transmitted, and can select a specific PSFCH resource (e.g., a specific PSFCH RB and / or a specific sequence index) from multiple reusable PSFCH resources (e.g., multiple sequences in multiple PSFCH RBs) based on the TX ID and / or RX ID. According to the transmission scheme of HARQ-ACK (e.g., ACK, NACK), the RX ID can be set to 0.

[0237] When multiple PSFCH opportunities are configured, the PSFCH opportunity index may be additionally considered to avoid conflicts with existing PSFCH resources. The operation of selecting existing PSFCH resources may be the same as the selection operation when the PSFCH opportunity index is 0 (e.g., PSFCH opportunity #0). Thereafter, for additional PSFCH opportunities, additional PSFCH opportunity indexes (e.g., PSFCH opportunities #1, #2, ..., #N-1) may be applied. According to the above method, conflicts with existing PSFCH resources may be prevented. The PSFCH opportunity index may be applied to the above process of selecting a PSFCH RB based on the position of a time slot and / or a subchannel and / or the above process of selecting a PSFCH resource from a selected PSFCHRB.

[0238] Specifically, when the PSFCH opportunity index is n, in order to indicate the slot index (for example, the slot index may refer to the slot index within the PSFCH period, and the slot index may be different from the general slot index) in the process of selecting a PSFCH RB (channel), (i+n) may be applied instead of i, and in order to indicate the subchannel index, (j+n) may be applied instead of j. When the above method is applied in the process of selecting a PSFCH resource from the selected PSFCH RB, (PID+MID+n) may be applied instead of (PID+MID). As another method, the number of PSFCH RBs for each of the N PSFCH opportunities may be set to N, and the N PSFCH opportunities may be configured to be selected in a one-to-one correspondence with the N PSCCH RBs.

[0239] When the PSFCH opportunity index is 0, the PSFCH resource (e.g., cyclic shift) may be configured to be selected within the first PSCCH RB among the N PSFCH RBs. When the PSFCH opportunity index is 1, the PSFCH resource (e.g., cyclic shift) may be configured to be selected within the second PSFCH RB among the N PSFCH RBs. When the PSFCH opportunity index is 2, the PSFCH resource (e.g., cyclic shift) may be configured to be selected within the third PSFCH RB among the N PSFCH RBs. When the PSFCH opportunity index is N-1, the PSFCH resource (e.g., cyclic shift) may be selected within the Nth PSCCH RB among the N PSFCH RBs.

[0240] When multiple PSFCH opportunities are configured, PSFCH resources corresponding to additional PSFCH opportunities can be configured independently of existing PSFCH resources. PSFCH resources can be configured for each resource pool. PSFCH resources can be indicated by a bitmap. Separate from existing PSFCH resources, resources for multiple PSFCH opportunities can be indicated by a bitmap. Existing PSFCH resources can be used for PSFCH transmissions corresponding to PSFCH opportunity #0 (e.g., existing PSCCH transmissions). PSFCH resources for additional PSFCH opportunities can be used for PSCCH transmissions corresponding to PSFCH opportunities #1, #2, ..., and #N-1.

[0241] Fig.17a is a conceptual diagram showing a first exemplary embodiment of a resource configuration method for multiple PSFCH opportunities, Fig.17b is a conceptual diagram showing a second exemplary embodiment of a resource configuration method for multiple PSCCH opportunities.

[0242] See also Fig.17a and Fig.17b , PSFCH resources for N PSFCH opportunities may be configured. Here, N may be 4. When N PSFCH opportunities are configured, PSFCH resources corresponding to the remaining (N-1) PSFCH opportunities (e.g., existing PSFCH opportunities) other than the first PSFCH opportunity may be configured independently of the PSFCH resources corresponding to the first PSFCH opportunity. The PSFCH resources corresponding to the first PSFCH opportunity may be existing PSFCH resources and / or PSCCH resources corresponding to PSFCH opportunity #0.

[0243] exist Fig.17a In an exemplary embodiment of the present invention, PSFCH resources corresponding to three PSFCH opportunities may be independently configured. For example, PSFCH resource #1 corresponding to PSFCH opportunity #1 may be configured, PSFCH resource #2 corresponding to PSFCH opportunity #2 may be configured, and PSFCH resource #3 corresponding to PSFCH opportunity #3 may be configured. PSFCH resource #1, PSFCH resource #2, and PSFCH resource #3 may not overlap with each other.

[0244] exist Fig.17bIn an exemplary embodiment of , one PSFCH resource (e.g., a common PSFCH resource region) may be configured corresponding to three PSFCH opportunities (e.g., (N-1) PSFCH opportunities). In this case, in order to prevent conflicts between PSFCH transmissions in the three PSFCH opportunities, it may be necessary to apply a PSFCH opportunity index in the process of selecting a PSFCH resource (e.g., a PSFCH resource within the common PSFCH resource region). Fig.17a and / or Fig.17b In an exemplary embodiment of the present invention, PSFCH resources are configured in a localized form in the frequency domain, but PSFCH resources may also be configured in other forms. For example, PSFCH resources may be configured in a distributed form in the frequency domain. PSFCH resources may be indicated by a bitmap.

[0245] To meet the OCB regulations in unlicensed bands, staggered RBs may be used for transmission. An interleaving index and a subchannel index may be configured. When multiple RB sets may be used for transmission, the scheduling information may include an RB set index. When an interleaving index and an RB set index exist, the interleaving index and the RB set index may be used to determine a PSFCH resource (e.g., a PSFCH resource region).

[0246] In SL communication, the subchannel index and slot index of the PSSCH can be used to determine the RB subgroup (e.g., one or more preconfigured 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 subgroup and the cyclic shift pair index of 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 subgroup, the RB index, or the cyclic shift pair index.

[0247] The interleaving index may replace the subchannel index. In the process of determining the RB subgroup, the interleaving index may be used instead of the subchannel index. The RB set index may be applied in the process of determining the RB subgroup. The subchannel index may be configured as a combination of the interleaving index and the RB set index. In this case, the RB subgroup may be determined by considering the subchannel index instead of the interleaving index and the RB set index. In order to determine the RB subgroup, the subchannel index and the time slot index may be considered simultaneously.

[0248] In an unlicensed frequency band, a communication node (e.g., a base station or a terminal) may perform an LBT operation. When the LBT operation is successful, the communication may ensure a transmission opportunity (e.g., COT) of a channel and / or a signal, and may transmit the channel and / or the signal within the ensured transmission opportunity. When a predetermined time (e.g., T gap) When the transmission is not performed, the communication node may lose the transmission opportunity. Then, when the transmission is needed again, the communication node can perform the LBT operation, and the transmission can be performed when the LBT operation is successful.

[0249] The PSFCH may be transmitted within the COT, and a guard symbol for switching between a transmission operation and a reception operation may exist between a PSSCH resource (e.g., a PSSCH symbol) and a PSFCH resource (e.g., a PSFCH symbol). If the length of the guard symbol is longer than a predetermined time (e.g., T gap ), the communication node can perform LBT operation for PSFCH transmission within COT. When LBT operation fails, the communication node may not be able to perform PSFCH transmission. In order to solve the above problem, the communication node can reduce the length of the protection symbol by extending the cyclic prefix (CP) of PSFCH. When the length of the protection symbol remaining after the CP extension of PSFCH is less than T gap When the communication node performs PSFCH transmission without performing LBT operation in COT, the problem of PSFCH transmission failure caused by LBT operation failure in COT can be solved.

[0250] The transmission frequency band of the channel and / or signal in the unlicensed frequency band can be configured to meet the OCB regulations. Since PSFCH format 0 includes one RB, PSFCH format 0 does not meet the OCB regulations. A method for solving the above problem is needed. In order to meet the OCB regulations, PSFCH format 0 can be configured to have an interlaced structure. In this case, PSFCH format 0 can be distributed in the frequency domain (e.g., the entire channel bandwidth, the frequency region within the resource pool, etc.). PSFCH format 0 can be transmitted repeatedly. When PSFCH format 0 is distributed in the frequency domain within the resource pool and PSCCH format 0 is transmitted repeatedly, the number of PSFCH format 0 repetitions in the frequency domain and / or the interval between PSFCH format 0 repetitions in the frequency domain can be implicitly identified by considering the OCB regulations and / or the resource pool (e.g., the entire resource pool). As another method, the number of PSFCH format 0 repetitions in the frequency domain and / or the interval between PSCCH format 0 repetitions in the frequency domain can be explicitly signaled. For example, the number of repetitions of PSFCH format 0 in the frequency domain and / or the interval between repetitions of PSFCH format 0 in the frequency domain may be signaled together with the resource pool configuration information.

[0251] Since the same PSFCH format 0 is repeatedly transmitted in the frequency domain according to the above method, the OCB regulations can be met. The reception performance of PSFCH (e.g., PSFCH format 0) can be improved. When the same PSFCH format 0 is repeatedly transmitted in the frequency domain, resource efficiency may be reduced because more resources are required compared to the existing PSFCH transmission process. As another method, the new PSFCH format can be configured to have an interleaved structure in the frequency domain (e.g., the entire frequency domain), and the number of RBs of the new PSCCH format can be configured to meet the OCB regulations.

[0252] The existing PSFCH format 0 can be transmitted through one RB. The existing PSFCH format 0 may be composed of a low peak to average power ratio (PAPR) sequence (e.g., a Zadoff-Chu sequence) of length 12. When the number of RBs specified by the OCB is M, the new PSFCH format may be composed of a low PAPR sequence of length M×12. M may be a natural number. The new PSFCH format may have an interleaved structure. The new PSFCH format may be transmitted as a format distributed in a channel bandwidth (e.g., the entire channel bandwidth). In this case, due to the increase in the length of the sequence, the amount of feedback information that can be multiplexed in the new PSCCH format may increase compared to the existing PSFCH format 0. The feedback information may refer to HARQ-ACK, HARQ feedback information, HARQ response and / or HARQ information bits. The mapping relationship between a specific sequence and feedback information within the new PSCCH format may be defined in consideration of the amount of feedback information that can be multiplexed in the new PSFCH format.

[0253] Fig.18a is a conceptual diagram showing a first exemplary embodiment of a PSFCH transmission method, Fig.18b is a conceptual diagram showing a second exemplary embodiment of a PSFCH transmission method.

[0254] See also Fig.18a , PSFCH format 0 (for example, the existing PSFCH format 0) can be transmitted in a distributed manner in the frequency domain. The same PSFCH format 0 can be transmitted repeatedly in the frequency domain. Fig.18a In an exemplary embodiment of , the transmission of PSFCH format 0 can meet the OCB regulations. Fig.18a In an exemplary embodiment of the present invention, RB-based cyclic shift hopping may be applied.

[0255] See also Fig.18b , a new PSFCH format with a long sequence can be transmitted in a distributed manner in the frequency domain. The new PSFCH format can be defined as PSFCH format 1. Fig.18bIn an exemplary embodiment of the present invention, the transmission of the new PSFCH format can meet the OCB regulation. The PAPR when the new PSFCH format is repeatedly transmitted in the frequency domain can be higher than the PAPA when the existing PSFCH format is distributedly transmitted in the frequency domain. In order to reduce the PAPR, Fig.18b RB-based cyclic shift hopping may be applied in an exemplary embodiment of the present invention.

[0256] As another method, the feedback information may be transmitted through the existing PSFCH format 0, and the transmission may be performed through redundant RBs to meet the OCB regulations. Redundant RBs may be commonly applied to multiple terminals, and the terminal may simultaneously perform a PSFCH transmission operation and a transmission operation of any signal (e.g., a predefined signal) in the redundant RB. According to the above method, the OCB regulations may be met. Since the signal transmitted in the redundant RB does not include special information, resource efficiency may be reduced according to the signal transmission in the redundant RB. Therefore, the redundant RB may include the minimum RB that meets the OCB regulations.

[0257] Redundant RBs can be configured to be distributed in the frequency domain (e.g., the entire frequency domain). Redundant RBs can be applied to all terminals in common. Redundant RBs can be configured not to overlap with RBs transmitted by existing PSFCH. The location of redundant RBs can be configured to the terminal via signaling (e.g., system information, PC5-RRC signaling, UE-specific RRC signaling, control information). Redundant RBs can be configured statically, semi-statically, or dynamically. Redundant RBs can be configured for each resource pool.

[0258] The position of the actual PSFCH transmission can be configured based on the position of the PSSCH associated with the actual PSFCH transmission (e.g., time slot position), the position of the subchannel, the TX ID, the RX ID and / or the PSFCH opportunity index. The redundant RBs can be configured (e.g., selected) in consideration of the position of the actual PSFCH transmission. Resources for PSFCH transmission can be preconfigured for each resource pool, and the redundant RBs can be configured (e.g., selected) in consideration of the resources for PSFCH transmission. All redundant RBs or some redundant RBs can be selected according to the position of the PSFCH transmission (e.g., the actual PSCCH transmission). The process of selecting redundant RBs according to the position of the PSFCH transmission can be predefined. Alternatively, the terminal can select redundant RBs on an implementable basis.

[0259] For example, the terminal may exclude the remaining redundant RBs among all redundant RBs, which do not include RBs adjacent to the RB (dedicated RB) transmitting the PSFCH. The excluded RBs may be RBs that meet specific criteria. The RBs that meet specific criteria may be RBs within a predetermined frequency distance or a predetermined number of RBs from the RB transmitting the PSFCH. When all RBs are included in RBs within a predetermined number of RBs starting from the RB transmitting the PSFCH, all RBs may be defined as RBs that meet specific criteria. Alternatively, when some RBs are included in RBs within a predetermined number of RBs of the RB transmitting the PSFCH, these RBs may be defined as RBs that meet specific criteria. If a portion of an RB (e.g., some subcarriers) belongs to an RB within a predetermined frequency distance or a predetermined number of RBs from the RB transmitting the PSFCH, the communication node may determine that the portion or the entire RB meets specific criteria.

[0260] The predetermined frequency distance and / or the predetermined number of RBs may be configured to the terminal via signaling (e.g., system information, PC5-RRC signaling, UE-specific RRC signaling, control information). The predetermined frequency distance and / or the predetermined number of RBs may be configured statically, semi-statically, or dynamically. The predetermined frequency distance and / or the predetermined number of RBs may be configured for each resource pool.

[0261] Fig.19a is a conceptual diagram showing a first exemplary embodiment of PSFCH transmission with redundant RBs, Fig.19b is a conceptual diagram showing a second exemplary embodiment of PSFCH transmission with redundant RBs; Fig.19c is a conceptual diagram showing a third exemplary embodiment of PSFCH transmission with redundant RBs.

[0262] See also Figures 19a to 19c , PSFCH transmission and transmission of a signal (eg, an arbitrary signal) in a redundant RB may be performed together. The redundant RB may be referred to as a common RB. The terminal may select a redundant RB according to the location of the PSFCH transmission (eg, the actual PSFCH transmission).

[0263] exist Fig.19a In an exemplary embodiment of the present invention, PSFCH resources and redundant RBs may be configured. In the frequency domain, PSFCH resources (e.g., PSCCH resource regions) may be configured in units of two RBs, and redundant RBs may be configured between PSFCH sources. PSFCH resources may be used for PSFCH transmission, and at least one of the redundant RBs may be used to transmit any signal. Among the redundant RBs, a redundant RB located within two RBs of a PSFCH resource that actually performs PSFCH transmission may not be used to transmit any signal. Fig.19aThe configuration of PSFCH resources and redundant RBs in the exemplary embodiment of Fig.19b and / or Fig.19c An exemplary embodiment of .

[0264] exist Fig.19b In an exemplary embodiment of , actual PSFCH transmission may be performed in PSFCH resource #A. In this case, redundant RB #X located within two RBs of PSFCH resource #A may not be used to transmit any signal. In other words, the terminal may transmit any signal in redundant RBs other than redundant RB #X in the redundant RBs.

[0265] exist Fig.19c In an exemplary embodiment of , actual PSFCH transmission may be performed in PSFCH resource #B. In this case, redundant RBs #Y and #Z located in two RBs of PSFCH resource #B may not be used to transmit any signal. In other words, the terminal may transmit any signal in the remaining redundant RBs except for redundant RBs #Y and #Z in the redundant RBs.

[0266] When a redundant RB for transmitting an arbitrary signal is selected based on the position of a PSFCH resource for performing actual PSFCH transmission, interference between PSFCH transmission and transmission of an arbitrary signal can be reduced, and unnecessary transmission power can be reduced. Therefore, PSFCH transmission can be performed efficiently.

[0267] The PAPR when the transmission of an arbitrary signal and PSFCH transmission are performed simultaneously in a redundant RB set with an interlaced structure may be higher than the PAPR during the existing PSFCH transmission. When the transmission of an arbitrary signal and PSFCH transmission are performed simultaneously in a redundant RB set with an interlaced structure, RB-based cyclic shift hopping can be applied to reduce the PAPR. When there is a PSFCH transmission period (e.g., PSFCH opportunity) within the COT and the terminal does not transmit PSFCH during the PSFCH transmission period, the terminal may lose the COT. Even when PSFCH transmission is not required within the COT, the terminal can transmit an arbitrary signal in the redundant RB within the COT to maintain the COT. When the COT is maintained by the above method, resources can be used efficiently.

[0268] The number of dedicated RBs (e.g., 1, 2, or 5) for actually performing PSFCH transmission can be pre-configured. The interval between a common RB (e.g., a redundant RB) and a dedicated RB in the frequency domain can be 1 MHz. The interval between a common RB and a dedicated RB can be pre-configured. The above configuration operation can be performed through signaling. The common RB can have an interlaced structure. When the interval between a common RB and a dedicated RB in the frequency domain is less than or equal to a threshold, the terminal may not transmit any signal in the common RB. In this case, the terminal may perform PSFCH transmission in the dedicated RB without transmitting any signal. When the interval between a common RB and a dedicated RB in the frequency domain exceeds a threshold, the terminal may simultaneously perform transmission of any signal in the common RB and transmission of PSFCH in the dedicated RB. Transmission of any signal and PSFCH transmission can be multiplexed in the frequency domain. The threshold can be configured to the terminal through signaling. PSFCH transmission methods can be classified as follows.

[0269] -PSFCH transmission method 1: A PSFCH format (eg, PSFCH format 0) may have a staggered structure, and the PSFCH format may be repeatedly transmitted in the frequency domain.

[0270] -PSFCH transmission method 2: PSFCH transmission in a dedicated RB and transmission of an arbitrary signal in a common RB may be performed together.

[0271] In PSFCH transmission method 1 and / or 2, cyclic shift hopping may be applied. The PSFCH transmission method may be pre-configured for each resource pool or SL-BWP. For example, PSFCH transmission method 1 for the first resource pool may be configured by signaling, and PSFCH transmission method 2 for the second resource pool may be configured by signaling.

[0272] For the transmission operation of SL channels and / or signals (e.g., PSSCH, PSCCH) other than PSFCH in the unlicensed frequency band, it may be necessary to meet the requirements of LBT operation and / or OCB regulations. PSSCH transmission can be performed to meet the OCB regulations. PSSCH resources can be configured to have an interlaced structure in the frequency domain. When the PSSCH resources have an interlaced structure to meet the OCB regulations, a terminal receiving PSSCH in the PSSCH resources can transmit PSFCH for PSSCH in the resources corresponding to the PSSCH resources. In this case, the transmission of PSFCH can meet the OCB regulations.

[0273] When PSFCH transmission is performed within the COT, transmission conflicts between terminals can be prevented. When PSFCH transmission is required outside the COT, PSFCH transmission can be performed based on the proposed method. The terminal can implicitly identify whether PSFCH transmission can be performed within the COT based on the reception time of PSSCH, PSFCH cycle, transmission-related timeline and / or COT duration. Alternatively, information about whether PSFCH transmission can be performed within the COT can be explicitly indicated to the terminal by signaling (e.g., a 1-bit indicator (e.g., COT indicator) included in the SCI).

[0274] When multiple PSFCH opportunities cannot be guaranteed and the LBT operation for PSFCH transmission fails, or when the LBT operation for PSCCH transmission fails and it is impossible to delay PSFCH transmission to the next PSFCH resource, the terminal can transmit HARQ-ACK (e.g., feedback information) through SCI. In other words, the terminal can transmit SCI including HARQ-ACK. The terminal can notify HARQ-ACK using a 1-bit indicator included in SCI. SCI may also include information about the PSSCH associated with the HARQ-ACK indicated by SCI (e.g., information for identifying PSSCH). For example, the SCI including HARQ-ACK may also include the TX ID and / or RX ID of the PSSCH associated with HARQ-ACK. The TX ID of PSSCH can be replaced with the TX ID or RX ID of SCI (e.g., existing SCI or PSCCH). The RX ID of PSSCH can be replaced with the RX ID or TX ID of SCI (e.g., existing SCI or PSCCH). The SCI including the HARQ-ACK may also include information about the time slot and / or subchannel (eg, the first subchannel) in which the PSSCH associated with the HARQ-ACK is transmitted. The information about the time slot may indicate a time slot index. The information about the subchannel may indicate a subchannel index.

[0275] The SCI including HARQ-ACK may be the first-stage SCI or the second-stage SCI. The SCI including HARQ-ACK may include scheduling information of the PSSCH. In this case, the terminal may transmit the SCI including the HARQ-ACK and the scheduling information, and may transmit data on the PSSCH scheduled by the SCI. When the data does not exist, the terminal may transmit a dummy signal on the PSSCH scheduled by the SCI. Alternatively, when the data does not exist, the terminal may not perform transmission on the PSSCH scheduled by the SCI.

[0276] In order to distinguish between a state of transmitting data on the PSSCH and a state of transmitting a virtual signal on the PSSCH, or to distinguish between a state of transmitting data on the PSSCH and a state of not performing transmission on the PSSCH, the SCI may include a specific field indicating a specific state. The first state indicated by the specific field included in the SCI may indicate a state of transmitting data on the PSSCH. The second state indicated by the specific field included in the SCI may indicate a state of transmitting a virtual signal on the PSSCH. The third state indicated by the specific field included in the SCI may indicate a state of not performing transmission on the PSSCH.

[0277] Multiple RB sets may need to be considered in PSCCH transmission, PSSCH transmission and / or PSFCH transmission. Data may be transmitted through multiple RB sets with an interleaved structure. In this case, the SCI (e.g., the SCI for scheduling data transmission) may include a specific RB set index for PSFCH transmission. The transmitting terminal may transmit the SCI including scheduling information and a specific RB set index for PSFCH transmission to the receiving terminal. The transmitting terminal may transmit data to the receiving terminal based on the scheduling information included in the SCI. The receiving terminal may receive the SCI from the transmitting terminal and may identify the scheduling information included in the SCI and the specific RB set index for PSFCH transmission.

[0278] The receiving terminal may receive data from the transmitting terminal based on the scheduling information included in the SCI. The receiving terminal may perform an LBT operation on a specific RB set indicated by the SCI to perform PSFCH transmission on the data. When the LBT operation of a specific RB set is successful, the receiving terminal may perform PSFCH transmission through the specific RB set. When the LBT operation of a specific RB set fails, the terminal may not be able to perform PSFCH transmission. In this case, SL performance may be reduced. In order to solve the above problem, information indicating the use of multiple RB sets for PSFCH transmission may be transmitted by a signal. In the above signaling process, multiple RB sets in all RB sets may be indicated by RB set indexes and / or bitmaps. When indicating PSFCH transmission using multiple RB sets, the terminal may perform an LBT operation on each of the multiple RB sets, and may perform PSFCH transmission in the RB set where the LBT operation is successful. When the LBT operation is successful in two or more RB sets, the terminal may repeatedly transmit the same PSFCH in the two or more RB sets.

[0279] The operation of the method according to the exemplary embodiment of the present invention can be implemented as a computer-readable program or code in a computer-readable recording medium. The computer-readable recording medium may include a recording device of all types having stored therein data that can be read by a computer system. In addition, the computer-readable recording medium may store and execute programs or codes, which may be distributed in a computer system connected via a network and read by a computer in a distributed manner.

[0280] Computer readable recording media may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM or flash memory. Program instructions may include not only machine language codes created by a compiler, but also high-level language codes that can be executed by a computer using an interpreter.

[0281] Although some aspects of the present invention have been described in the context of an apparatus, these aspects may be indicated according to the corresponding description of the method, and a block or apparatus may correspond to the steps of the method or the features of the steps. Similarly, the aspects described in the context of the method may be represented as the features of the corresponding blocks or items or corresponding apparatus. Some or all steps of the method may be performed by (or using) hardware devices such as microprocessors, programmable computers or electronic circuits. In some embodiments, one or more of the most important steps of the method may be performed by such an apparatus.

[0282] In some exemplary embodiments, a programmable logic device such as a field programmable gate array can be used to perform some or all of the functions of the methods described herein. In some exemplary embodiments, the field programmable gate array can be operated with a microprocessor to perform one of the methods described herein. Typically, the method is preferably performed by a specific hardware device.

[0283] The description of the present invention is merely exemplary in nature, and therefore variant forms that do not deviate from the essence of the present invention are intended to be within the scope of the present invention. Such variant forms should not be considered as departing from the spirit and scope of the present invention. Therefore, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope defined by the appended claims.

Claims

1. A method of a first terminal, comprising: receiving sidelink control information (SCI) from the second terminal; receiving data scheduled by the SCI from the second terminal; generating a hybrid automatic repeat request acknowledgment (HARQ-ACK) for the data; as well as A listen-before-transmit (LBT) operation for transmitting the HARQ-ACK is performed in a first PSFCH opportunity among N physical sidelink feedback channel (PSFCH) opportunities configured in the first terminal, where N is a natural number.

2. The method according to claim 1, wherein: The N PSFCH opportunities include the first PSFCH opportunity and (N-1) PSFCH opportunities, and the first PSFCH opportunity and the (N-1) PSFCH opportunities are configured by one message or independently configured by different messages.

3. The method according to claim 1, wherein: The SCI includes first information indicating whether the N PSFCH opportunities are applied. When the first information indicates that the N PSFCH opportunities are applied, the N PSFCH opportunities are used to transmit HARQ-ACK, and when the first information indicates that the N PSFCH opportunities are not applied, only the first PSFCH opportunity is used to transmit HARQ-ACK.

4. The method according to claim 1, wherein: When the first terminal cannot transmit ARQ-ACK within a channel occupancy time (COT), the N PSFCH opportunities are used to transmit HARQ-ACK.

5. The method according to claim 1, further comprising: In response to the first LBT operation failing, performing a second LBT operation in a second PSFCH opportunity among the N PSFCH opportunities for transmitting the HARQ-ACK; as well as In response to the second LBT operation being successful, a PSFCH format including the HARQ-ACK is transmitted to the second terminal in the second PSFCH opportunity.

6. The method according to claim 5, wherein: The PSFCH format is retransmitted in the frequency domain.

7. The method according to claim 5, further comprising: A first signal is transmitted, wherein transmitting the PSFCH format and transmitting the first signal are multiplexed in the frequency domain, transmitting the PFSCH format is performed in a dedicated resource block (RB) in the frequency domain, and transmitting the first signal is performed in a common RB in the frequency domain.

8. The method according to claim 7, wherein: When a frequency interval between the dedicated RB and the common RB exceeds a threshold, transmitting the first signal is performed in the common RB.

9. The method according to claim 1, further comprising: A first signal is transmitted in the common RB to maintain the COT.

10. A method of a second terminal, comprising: transmitting sidelink control information (SCI) to the first terminal; transmitting data scheduled by the SCI to the first terminal; as well as A monitoring operation is performed in one or more PSFCH opportunities among N physical sidelink feedback channel (PSFCH) opportunities configured in the first terminal to receive a hybrid automatic repeat request acknowledgement (HARQ-ACK) of the data, where N is a natural number.

11. The method according to claim 10, wherein: The N PSFCH opportunities include the first PSFCH opportunity and (N-1) PSFCH opportunities, and the first PSFCH opportunity and the (N-1) PSFCH opportunities are configured by one message or independently configured by different messages.

12. The method according to claim 10, wherein: The SCI includes first information indicating whether the N PSFCH opportunities are applied, when the first information indicates that the N PSFCH opportunities are applied, the N PSFCH opportunities are used to transmit the HARQ-ACK, and when the first information indicates that the N PSFCH opportunities are not applied, only the first PSFCH opportunity is used to transmit the HARQ-ACK.

13. The method according to claim 10, wherein: When the first terminal cannot transmit the ARQ-ACK within a channel occupancy time (COT), the N PSFCH opportunities are used to transmit the HARQ-ACK.

14. The method according to claim 10, further comprising: A PSFCH format including the HARQ-ACK is received from the first terminal based on the monitoring operation.

15. The method according to claim 14, wherein: The PSFCH format is repeatedly received in the frequency domain, or is received in a dedicated resource block (RB) in the frequency domain.

16. A first terminal, comprising a processor, in, The processor causes the first terminal to execute: receiving sidelink control information (SCI) from the second terminal; receiving data scheduled by the SCI from the second terminal; generating a hybrid automatic repeat request acknowledgment (HARQ-ACK) for the data; as well as A listen-before-transmit (LBT) operation for transmitting the HARQ-ACK is performed in a first PSFCH opportunity among N physical sidelink feedback channel (PSFCH) opportunities configured in the first terminal, where N is a natural number.

17. The first terminal according to claim 16, wherein: The SCI includes first information indicating whether the N PSFCH opportunities are applied, when the first information indicates that the N PSFCH opportunities are applied, the N PSFCH opportunities are used to transmit the HARQ-ACK, and when the first information indicates that the N PSFCH opportunities are not applied, only the first PSFCH opportunity is used to transmit the HARQ-ACK.

18. The first terminal according to claim 16, wherein: When the first terminal cannot transmit the ARQ-ACK within a channel occupancy time (COT), the N PSFCH opportunities are used to transmit the HARQ-ACK.

19. The first terminal according to claim 16, wherein: The processor further causes the first terminal to execute: In response to the first LBT operation failing, performing a second LBT operation in a second PSFCH opportunity among the N PSFCH opportunities for transmitting the HARQ-ACK; as well as In response to the second LBT operation being successful, a PSFCH format including the HARQ-ACK is transmitted to the second terminal in the second PSFCH opportunity.

20. The first terminal according to claim 19, wherein: The processor further causes the first terminal to transmit a first signal, wherein transmitting the PSFCH format and transmitting the first signal are multiplexed in the frequency domain, transmitting the PSFCH format is performed in a dedicated resource block (RB) in the frequency domain, and transmitting the first signal is performed in a common RB in the frequency domain.

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