Method and device for transmitting sidelink resource coordination information

Abstract

SOLUTION: An operation method of a first terminal for performing sidelink communication in a communication system includes receiving resource adjustment information from a second terminal, selecting a candidate resource to be used for transmission of the first terminal by preferentially considering one or more preferred resources when the resource adjustment information is information on the one or more preferred resources, and excluding one or more non-preferred resources from the candidate resource to be used for transmission of the first terminal when the resource adjustment information is information on one or more non-preferred resources.EFFECT: Efficient transmission of the sidelink resource coordination information improves the overall performance of the communication system.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a sidelink communication technology, and more particularly to a method and apparatus for transmitting resource coordination information in sidelink communication. [Background technology]

[0002] Even when resource allocation mode 2 is used in sidelink communication, a terminal (i.e., a coordinating terminal) can be configured to adjust resources for data transmission and reception between terminals, as in mode 1, and notify terminals (i.e., coordinated terminals) that need to transmit and receive data of information about the adjusted resources (i.e., resource adjustment information). Because terminals perform data transmission and reception operations within the adjusted resources, collisions between resources can be prevented, thereby improving performance. In addition, energy efficiency can be improved by terminals performing sensing and selection operations within limited resources. Summary of the Invention [Problem to be solved by the invention]

[0003] In order to solve the above problems, an object of the present invention is to provide a method for transmitting resource adjustment information for sidelink communication.

[0004] Another object of the present invention to solve the above problems is to provide a configuration of an apparatus for performing the method for transmitting resource coordination information for sidelink communication. [Means for solving the problem]

[0005] According to one embodiment of the present invention to achieve the above object, an operating method of a first terminal performing sidelink communication may include: receiving resource adjustment information from a second terminal; if the resource adjustment information is information on one or more preferred resources, selecting candidate resources to be used for transmission of the first terminal by preferentially considering the one or more preferred resources; and if the resource adjustment information is information on one or more non-preferred resources, excluding the one or more non-preferred resources from candidate resources to be used for transmission of the first terminal.

[0006] The second terminal may be a terminal that receives data transmitted by the first terminal.

[0007] The resource adjustment information may be received through a medium access control (MAC) control element (CE), or may be received through a MAC CE and sidelink control information (SCI).

[0008] Whether the resource adjustment information is received through the MAC CE or through the MAC CE and SCI can be set for each resource pool.

[0009] The resource adjustment information includes N (N is a natural number greater than or equal to 1) TRIV (Time Resource Indication Value) and FRIV (Frequency Resource Indication Value) combinations, and each of the N TRIV and FRIV combinations can indicate M (M is a natural number greater than or equal to 1) resources.

[0010] The time and frequency locations of the first resource among the M resources indicated by each of the N TRIV and FRIV combinations may be additionally included in the resource coordination information.

[0011] The frequency location of the first resource may be indicated by a starting subchannel index.

[0012] The time position of the first resource among the M resources indicated by the first TRIV and FRIV combination among the N TRIV and FRIV combinations is indicated by a reference slot, and the time positions of the first resources of the remaining TRIV and FRIV combinations, excluding the first TRIV and FRIV combination among the N TRIV and FRIV combinations, can be indicated by slot offsets relative to the reference slot.

[0013] The range of resources indicated by the N TRIV and FRIV combinations when the resource adjustment information is received through the MAC CE may be different from the range of resources indicated by the N TRIV and FRIV combinations when the resource adjustment information is received through the MAC CE and SCI.

[0014] The resource adjustment information may be received from the second terminal based on an explicit request of the first terminal, or may be received from the second terminal upon satisfaction of a predetermined condition without an explicit request of the first terminal.

[0015] According to one embodiment of the present invention to achieve the above object, an operating method of a second terminal performing sidelink communication includes: generating resource adjustment information, which is information on one or more preferred resources or one or more non-preferred resources for transmission of a first terminal; and transmitting the resource adjustment information to the first terminal, wherein if the resource adjustment information is information on one or more preferred resources, candidate resources to be used for transmission of the first terminal are selected by giving priority to the one or more preferred resources, and if the resource adjustment information is information on one or more non-preferred resources, the one or more non-preferred resources can be excluded from candidate resources to be used for transmission of the first terminal.

[0016] The resource adjustment information may be transmitted through a medium access control (MAC) control element (CE), or may be transmitted through a MAC CE and sidelink control information (SCI).

[0017] Whether the resource adjustment information is transmitted through the MAC CE or through the MAC CE and SCI can be set for each resource pool.

[0018] The resource adjustment information includes N (N is a natural number greater than or equal to 1) TRIV (Time Resource Indication Value) and FRIV (Frequency Resource Indication Value) combinations, and each of the N TRIV and FRIV combinations can indicate M (M is a natural number greater than or equal to 1) resources.

[0019] The time and frequency locations of the first resource among the M resources indicated by each of the N TRIV and FRIV combinations may be additionally included in the resource coordination information.

[0020] The time position of the first resource among the M resources indicated by the first TRIV and FRIV combination among the N TRIV and FRIV combinations is indicated by a reference slot, and the time positions of the first resources of the remaining TRIV and FRIV combinations, excluding the first TRIV and FRIV combination among the N TRIV and FRIV combinations, can be indicated by slot offsets relative to the reference slot.

[0021] The range of resources indicated by the N TRIV and FRIV combinations when the resource adjustment information is received through the MAC CE may be different from the range of resources indicated by the N TRIV and FRIV combinations when the resource adjustment information is received through the MAC CE and SCI.

[0022] According to one embodiment of the present invention to achieve the other object, a first terminal performing sidelink communication includes: at least one transceiver; and a processor controlling the at least one transceiver, wherein the processor can configure the first terminal to perform the following steps: receiving resource adjustment information from a second terminal using the at least one transceiver; if the resource adjustment information is information on one or more preferred resources, selecting candidate resources to be used for transmission of the first terminal by preferentially considering the one or more preferred resources; and if the resource adjustment information is information on one or more non-preferred resources, excluding the one or more non-preferred resources from candidate resources to be used for transmission of the first terminal.

[0023] The resource adjustment information includes N (N is a natural number greater than or equal to 1) TRIV (Time Resource Indication Value) and FRIV (Frequency Resource Indication Value) combinations, and each of the N TRIV and FRIV combinations can indicate M (M is a natural number greater than or equal to 1) resources.

[0024] The range of resources indicated by the N TRIV and FRIV combinations when the resource adjustment information is received through the MAC CE may be different from the range of resources indicated by the N TRIV and FRIV combinations when the resource adjustment information is received through the MAC CE and SCI. [Effects of the Invention]

[0025] According to embodiments of the present invention, sidelink resource coordination information can be transmitted efficiently, thereby improving the overall performance of the communication system. [Brief explanation of the drawings]

[0026] [Figure 1]1 is a conceptual diagram illustrating a first embodiment of a communication system. [Figure 2] 1 is a block diagram illustrating a first embodiment of a communication node that constitutes a communication system. [Figure 3] FIG. 1 is a conceptual diagram illustrating a first embodiment of a Type 1 frame structure. [Figure 4] FIG. 1 is a conceptual diagram illustrating a first embodiment of a type 2 frame structure. [Figure 5] 1 is a conceptual diagram illustrating a first embodiment of a method for transmitting SS / PBCH blocks in a communication system. [Figure 6] FIG. 1 is a conceptual diagram illustrating a first embodiment of an SS / PBCH block in a communication system. [Figure 7] FIG. 2 is a conceptual diagram illustrating a second embodiment of a method for transmitting SS / PBCH blocks in a communication system. [Figure 8a] FIG. 1 is a conceptual diagram illustrating RMSI CORESET mapping pattern #1 in a communication system. [Figure 8b] FIG. 10 is a conceptual diagram illustrating RMSI CORESET mapping pattern #2 in a communication system. [Figure 8c] FIG. 10 is a conceptual diagram illustrating RMSI CORESET mapping pattern #3 in a communication system. [Figure 9] FIG. 10 is a conceptual diagram illustrating an example of setting PSFCH resources used for transmitting HARQ ACK / NACK information. [Figure 10] FIG. 1 is a conceptual diagram illustrating an embodiment of a method for multiplexing a control channel and a data channel in sidelink communication. [Figure 11] 1 is a conceptual diagram for explaining a first embodiment of a signaling method for resource adjustment information according to the present invention; [Figure 12] FIG. 10 is a conceptual diagram illustrating a second embodiment of a method for signaling resource adjustment information according to the present invention. [Figure 13] 10 is a conceptual diagram illustrating an embodiment of a method for determining a transmission time point of a CI-PSFCH based on a slot in which a PSSCH in which a collision is predicted to occur is transmitted. FIG. [Figure 14]10 is a conceptual diagram illustrating an embodiment of a method for determining a transmission time point of a CI-PSFCH based on a slot in which an SCI used to predict collision is transmitted. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention can be modified in various ways and can have various embodiments, and a specific embodiment will be illustrated in the drawings and described in detail. However, it is not intended to limit the present invention to the specific embodiment, and it should be understood that the present invention includes all modifications, equivalents, and alternatives that fall within the spirit and technical scope of the present invention.

[0028] Terms such as "first," "second," etc. may be used to describe various components, but the components should not be limited by these terms. These terms are used only to distinguish one component from another. For example, a first component may be termed a "second component," and similarly, a second component may be termed a "first component," without departing from the scope of the present invention. The term "and / or" includes a combination of multiple associated listed items or any of multiple associated listed items.

[0029] In the examples of this application, "at least one of A and B" may mean "at least one of A or B" or "at least one of a combination of one or more of A and B." Also, in the examples of this application, "one or more of A and B" may mean "one or more of A or B" or "one or more of a combination of one or more of A and B."

[0030] In the embodiments of the present application, (re)transmission may mean "transmission," "retransmission," or "transmission and retransmission," (re)configuration may mean "configuration," "reconfiguration," or "configuration and reconfiguration," (re)connection may mean "connection," "reconnection," or "connection and reconnection," and (re)connection may mean "connection," "reconnection," or "connection and reconnection."

[0031] When a component is said to be "coupled" or "connected" to another component, it should be understood that it may be directly coupled or connected to the other component, but that there may be other components in between. Conversely, when a component is said to be "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0032] The terms used in this application are merely used to describe specific embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprise" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

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

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

[0035] A communication system to which an embodiment of the present invention is applied will now be described. The communication system to which an embodiment of the present invention is applied is not limited to the content described below, and the embodiment of the present invention may be applied to various communication systems. Here, the communication system may be used interchangeably with a communication network.

[0036] FIG. 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0037] 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. 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), etc.

[0038] The plurality of communication nodes 110 to 130 can support communication protocols defined by 3GPP (registered trademark; 3rd generation partnership project) standards (for example, LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.). The plurality of communication nodes 110 to 130 may support CDMA (code division multiple access) technology, WCDMA (wideband CDMA) technology, TDMA (time division multiple access) technology, FDMA (frequency division multiple access) technology, OFDM (orthogonal frequency division multiplexing) technology, Filtered OFDM technology, CP (cyclic prefix)-OFDM technology, DFT-s-OFDM (discrete Fourier transform-spread-OFDM) technology, OFDMA (orthogonal frequency division multiple access) technology, SC (single carrier)-FDMA technology, NOMA (non-orthogonal multiple access) technology, GFDM (generalized frequency division multiplexing) technology, FBMC (filter bank multi-carrier) technology, UFMC (universal filtered multi-carrier) technology, SDMA (space division multiple access) technology, etc. Each of the plurality of communication nodes may have the following structure.

[0039] FIG. 2 is a block diagram illustrating a first embodiment of a communication node that constitutes a communication system.

[0040] 2, a communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 that is connected to a network to perform communication. 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 is connected to a bus 270 to perform communication.

[0041] However, each component included in the communication node 200 may be connected through a separate interface or separate bus centered on the processor 210, rather than through a common bus 270. For example, the processor 210 may be connected to at least one of the memory 220, the transceiver 230, the input interface device 240, the output interface device 250, and the storage device 260 through a dedicated interface.

[0042] The processor 210 can execute program commands 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 methods according to embodiments of the present invention are performed. The memory 220 and the storage device 260 may each be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may be composed of at least one of a read-only memory (ROM) and a random access memory (RAM).

[0043] 1, the communication system 100 may include multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2, and multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. The first base station 110-1, the second base station 110-2, and the third base station 110-3 may each form a macro cell. The fourth base station 120-1 and the fifth base station 120-2 may each 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. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong within the cell coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong within the cell coverage of the third base station 110-3. The first terminal 130-1 may belong within the cell coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong within the cell coverage of the fifth base station 120-2.

[0044] Here, each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be referred to as a NodeB (NB), evolved NodeB (eNB), gNB, advanced base station (ABS), high reliability-base station (HR-BS), base transceiver station (BTS), radio base station, radio transceiver, access point, access node, radio access station (RAS), mobile multihop relay-base station (MMR-BS), relay station (RS), advanced relay station (ARS), high reliability-relay station (HR-RS), home NodeB (HNB), home eNodeB (HeNB), road side unit (RSU), radio remote head (RRH), transmission point (TP), transmission and reception point (TRP), etc.

[0045] Each of the multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may be referred to as a UE (user equipment), TE (terminal equipment), AMS (advanced mobile station), HR-MS (high reliability-mobile station), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, OBU (on board unit), etc.

[0046] Meanwhile, the base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands or the same frequency band. The base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other via an ideal backhaul link or a non-ideal backhaul link, and may exchange information via the ideal backhaul link or the non-ideal backhaul link. The base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to the core network via an ideal backhaul link or a non-ideal backhaul link. Each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can transmit signals received from the core network to corresponding terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6, and can transmit signals received from corresponding terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 to the core network.

[0047] In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can support MIMO transmission (e.g., single user (SU)-MIMO, multi user (MU)-MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in unlicensed bands, device-to-device communication (D2D) (or proximity services (ProSe)), Internet of Things (IoT) communication, dual connectivity (DC), etc. Here, each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 can perform operations corresponding to and supported by base stations 110-1, 110-2, 110-3, 120-1, and 120-2. For example, the second base station 110-2 can transmit a signal to the fourth terminal 130-4 based on the SU-MIMO scheme, and the fourth terminal 130-4 can receive a signal from the second base station 110-2 based on the SU-MIMO scheme. Alternatively, the second base station 110-2 can transmit signals to the fourth terminal 130-4 and the fifth terminal 130-5 based on the MU-MIMO scheme, and the fourth terminal 130-4 and the fifth terminal 130-5 can each receive signals from the second base station 110-2 using the MU-MIMO scheme.

[0048] The first base station 110-1, the second base station 110-2, and the third base station 110-3 can each transmit a signal to the fourth terminal 130-4 based on the CoMP scheme, 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 based on the CoMP scheme. Each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can transmit and receive signals to and from terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 within its cell coverage based on the CA scheme. The first base station 110-1, the second base station 110-2, and the third base station 110-3 can each control D2D between the fourth terminal 130-4 and the fifth terminal 130-5, and the fourth terminal 130-4 and the fifth terminal 130-5 can each perform D2D under the control of the second base station 110-2 and the third base station 110-3, respectively.

[0049] Meanwhile, a communication system can support three types of frame structures: Type 1 frame structure can be applied to an FDD (frequency division duplex) communication system, Type 2 frame structure can be applied to a TDD (time division duplex) communication system, and Type 3 frame structure can be applied to an unlicensed spectrum-based communication system (e.g., an LAA (licensed assisted access) communication system).

[0050] FIG. 3 is a conceptual diagram illustrating a first embodiment of a Type 1 frame structure.

[0051] 3, a radio frame 300 may include 10 subframes, and each subframe may include two slots. Therefore, the radio frame 300 may include 20 slots (e.g., slot #0, slot #1, slot #2, slot #3, ..., slot #18, slot #19). The length Tf of the radio frame 300 may be 10 milliseconds (ms), the length of a subframe may be 1 ms, and the slot length Tslot may be 0.5 ms. Here, Ts may indicate the sampling time, which may be 1 / 30,720,000 s (seconds).

[0052] A slot may consist of multiple OFDM symbols in the time domain and multiple resource blocks (RBs) in the frequency domain. A resource block may consist of multiple subcarriers in the frequency domain. The number of OFDM symbols that make up a slot may vary depending on the configuration of the cyclic prefix (CP). CPs may be classified as normal CPs and extended CPs. When a normal CP is used, a slot may consist of seven OFDM symbols, in which case a subframe may consist of 14 OFDM symbols. When an extended CP is used, a slot may consist of six OFDM symbols, in which case a subframe may consist of 12 OFDM symbols.

[0053] FIG. 4 is a conceptual diagram illustrating a first embodiment of a Type 2 frame structure.

[0054] Referring to Figure 4, a radio frame 400 may include two half frames, each of which may include five subframes. Therefore, the radio frame 400 may include ten subframes. The length Tf of the radio frame 400 may be 10 ms. The length of a half frame may be 5 ms. The length of a subframe may be 1 ms. Here, Ts may be 1 / 30,720,000 s.

[0055] The radio frame 400 may include a downlink subframe, an uplink subframe, and a special subframe. Each of the downlink subframe and the uplink subframe may include two slots. The slot length Tslot may be 0.5 ms. Among the subframes included in the radio frame 400, subframe #1 and subframe #6 may each be a special subframe. For example, if the downlink-uplink switching period is 5 ms, the radio frame 400 may include two special subframes. Alternatively, if the downlink-uplink switching period is 10 ms, the radio frame 400 may include one special subframe. The special subframe may include a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS).

[0056] The downlink pilot time slot may be considered as a downlink interval and may be used for a UE's cell search, time and frequency synchronization acquisition, channel estimation, etc. The guard interval may be used to solve an interference problem in uplink data transmission caused by a downlink data reception delay. The guard interval may also include the time required to switch from a downlink data reception operation to an uplink data transmission operation. The uplink pilot time slot may be used for uplink channel estimation, time and frequency synchronization acquisition, etc. Transmission of a physical random access channel (PRACH) or a sounding reference signal (SRS) may be performed in the uplink pilot time slot.

[0057] The lengths of the downlink pilot time slots, guard intervals, and uplink pilot time slots included in the special subframes may be variably adjusted as needed, and the number and locations of the downlink subframes, uplink subframes, and special subframes included in the radio frame 400 may be changed as needed.

[0058] In a communication system, a transmission time interval (TTI) may be a basic time unit for transmitting coded data through a physical layer. A short TTI may be used in a communication system to support low latency requirements. The length of the short TTI may be less than 1 ms. An existing TTI having a length of 1 ms may be referred to as a base TTI or regular TTI. That is, the base TTI may consist of one subframe. To support transmission in basic TTI units, signals and channels may be configured in subframe units. 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 exist in each subframe.

[0059] On the other hand, synchronization signals (e.g., primary synchronization signal (PSS) and secondary synchronization signal (SSS)) can exist every 5 subframes, and a physical broadcast channel (PBCH) can exist every 10 subframes. Radio frames can be distinguished by SFN, which can be used to define the transmission of signals whose transmission period is longer than one radio frame (e.g., paging signals, reference signals for channel estimation, signals indicating channel state information, etc.). The period of the SFN can be 1024.

[0060] In an LTE system, the PBCH may be a physical layer channel used to transmit system information (e.g., a master information block (MIB)). The PBCH may be transmitted every 10 subframes. That is, the transmission period of the PBCH may be 10 ms, and the PBCH may be transmitted once per radio frame. The same MIB may be transmitted for four consecutive radio frames, and after four consecutive radio frames, the MIB may be changed depending on the status of the LTE system. The transmission period of the same MIB may be referred to as a "PBCH TTI," and the PBCH TTI may be 40 ms. That is, the MIB may be changed for each PBCH TTI.

[0061] The MIB may be configured with 40 bits. Of the 40 bits constituting the MIB, 3 bits may be used to indicate a system band, 3 bits may be used to indicate PHICH (physical hybrid ARQ (automatic repeat request) indicator channel) related information, 8 bits may be used to indicate SFN, 10 bits may be set as reserved bits, and 16 bits may be used for CRC (cyclic redundancy check).

[0062] The SFN that separates radio frames may consist of a total of 10 bits (B9 to B0), of which the 8 most significant bits (MSBs) (B9 to B2) may be indicated by the PBCH (i.e., the MIB). The 8 most significant bits (B9 to B2) of the SFN indicated by the PBCH (i.e., the MIB) may be the same for four consecutive radio frames (i.e., the PBCH TTIs). The 2 least significant bits (LSBs) (B1 to B0) of the SFN may change for four consecutive radio frames (i.e., the PBCH TTIs) and may not be explicitly indicated by the PBCH (i.e., the MIB). The 2 least significant bits (LSBs) (B1 to B0) of the SFN may be implicitly indicated by the scrambling sequence for the PBCH (hereinafter referred to as the "PBCH scrambling sequence").

[0063] A gold sequence generated by initializing the cell ID may be used as the PBCH scrambling sequence, and the PBCH scrambling sequence may be initialized every four consecutive radio frames (i.e., PBCH TTI) by mod(SFN, 4). PBCHs transmitted in radio frames corresponding to an SFN whose two least significant bits (B1-B0) are set to '00' may be scrambled by the gold sequence generated by initializing the cell ID. Thereafter, the gold sequence generated by mod(SFN, 4) may be used to scramble PBCHs transmitted in radio frames whose two least significant bits (B1-B0) of the SFN are '01', '10', and '11'.

[0064] Therefore, a terminal that acquires a cell ID during the initial cell search process can implicitly find the value (e.g., "00," "01," "10," or "11") of the SFN's two least significant bits (B1-B0) through the PBCH scrambling sequence during the PBCH (i.e., MIB) decoding process. The terminal can identify the SFN (i.e., all bits (B9-B0) of the SFN) using the two least significant bits (B1-B0) of the SFN identified based on the PBCH scrambling sequence and the eight most significant bits (B9-B2) of the SFN indicated by the PBCH (i.e., MIB).

[0065] Evolved mobile communication networks beyond LTE must not only maintain high transmission speeds, which has been the primary focus in the past, but also meet technical requirements to support a wider variety of service scenarios. Recently, ITU-R defined the key performance indicators (KPIs) and requirements for IMT-2020, the official name for 5G mobile communications, which can be summarized as high transmission speeds (eMBB, enhanced Mobile Broadband), short transmission latency (URLLC, Ultra Reliable Low Latency Communication), and massive machine type communication (mMTC, massive terminal connectivity). According to the ITU-R's estimated timetable, the goal is to allocate frequencies for IMT-2020 in 2019 and complete international standard approval by 2020.

[0066] 3GPP is developing 5G standards based on new radio access technology (RAT) that meets the requirements of IMT-2020. According to the 3GPP definition, new radio access technology is a radio access technology that is not backward compatible with existing 3GPP radio access technology, and new wireless communication systems after LTE that adopt such radio access technology are referred to as New Radio (NR) in this specification.

[0067] One of the features that sets NR apart from the existing 3GPP systems, CDMA and LTE, is that it utilizes a wide range of frequency bands to increase transmission capacity. In relation to this, the ITU-sponsored WRC-15 has set the 24.25 to 86 GHz band as a candidate frequency band for IMT-2020 as an agenda item for the next WRC-19. 3GPP is considering the sub-1 GHz to 100 GHz band as NR candidate bands.

[0068] Waveform technologies being discussed for NR include orthogonal frequency division multiplexing (OFDM), filtered OFDM, generalized frequency division multiplexing (GFDM), filter bank multi-carrier (FBMC), and universal filtered multi-carrier (UFMC). While each has its own advantages and disadvantages, cyclic prefix (CP)-based OFDM and single carrier-frequency division multiple access (SC-FDMA) remain effective methods for 5G systems due to their relatively low transceiver implementation complexity and multiple-input multiple-output (MIMO) scalability. However, to flexibly support various 5G usage scenarios, it may be possible to simultaneously accommodate different waveform parameters on a single carrier without a guard band. Filtered OFDM and GFDM, which have frequency spectra with low out-of-band emissions (OOB), may be suitable for this purpose.

[0069] For convenience of explanation, the present invention will be described assuming CP-based OFDM as a waveform technology for wireless access. However, this is merely for convenience of explanation, and various embodiments of the present invention are not limited to a specific waveform technology. In general, the category of CP-based OFDM technology also includes Filtered OFDM and Spread Spectrum OFDM (e.g., DFT-spread OFDM).

[0070] The subcarrier spacing of a communication system (e.g., an OFDM-based communication system) may be determined based on factors such as carrier frequency offset (CFO). CFO may be caused by factors such as the Doppler effect and phase drift, and may increase in proportion to the operating frequency. Therefore, to prevent degradation of communication system performance due to CFO, the subcarrier spacing may increase in proportion to the operating frequency. However, as the subcarrier spacing increases, CP overhead may increase. Therefore, the subcarrier spacing may be set based on channel characteristics according to the frequency band, radio frequency (RF) characteristics, etc.

[0071] Various numerologies are considered in the NR system. For example, the subcarrier spacing of a communication system can be set to 15 kHz, 30 kHz, 60 kHz, or 120 kHz. The subcarrier spacing of an LTE system can be 15 kHz, and the subcarrier spacing of an NR system can be 1, 2, 4, or 8 times the existing subcarrier spacing of 15 kHz. If the subcarrier spacing increases in increments of an exponential multiple of 2 of the existing subcarrier spacing, the frame structure can be easily designed.

[0072] A communication system can support a wide frequency band (e.g., hundreds of MHz to tens of GHz). Because the diffraction and reflection characteristics of radio waves are poor in high frequency bands, propagation loss (e.g., path loss, reflection loss, etc.) in high frequency bands may be greater than propagation loss in low frequency bands. Therefore, the cell coverage of a communication system supporting a high frequency band may be smaller than that of a communication system supporting a low frequency band. To address this issue, a beamforming scheme based on multiple antenna elements may be used to increase cell coverage in a communication system supporting a high frequency band.

[0073] Beamforming methods can include digital beamforming, analog beamforming, hybrid beamforming, etc. In a communication system using digital beamforming, beamforming gain can be obtained using multiple RF paths based on a digital precoder or codebook. In a communication system using analog beamforming, beamforming gain can be obtained through analog RF devices (e.g., phase shifters, power amplifiers (PAs), variable gain amplifiers (VGAs), etc.) and antenna arrays.

[0074] Digital beamforming requires a high-performance digital-to-analog converter (DAC) or analog-to-digital converter (ADC) and a transceiver unit corresponding to the number of antenna elements, which can increase the complexity of antenna implementation in order to increase beamforming gain. In a communication system using analog beamforming, multiple antenna elements are connected to a single transceiver unit via a phase shifter, so increasing the beamforming gain may not significantly increase the complexity of antenna implementation. However, the beamforming performance of a communication system using analog beamforming may be lower than that of a communication system using digital beamforming. Furthermore, in a communication system using analog beamforming, the phase shifter is adjusted in the time domain, which may result in inefficient use of frequency resources. Therefore, a hybrid beamforming method, which combines digital and analog methods, may be used.

[0075] When cell coverage is increased by using beamforming, not only the control channels and data channels of each terminal but also common control channels and common signals (e.g., reference signals, synchronization signals) for all terminals belonging to the cell coverage can be transmitted based on the beamforming scheme. When applying beamforming to increase cell coverage and transmitting common control channels and signals to all terminals, it is difficult to transmit common control channels and signals to the entire cell coverage in a single transmission, and the common control channels and signals must be transmitted through multiple beams over a certain period of time. This transmission over several hours while changing multiple beams is called beam sweeping. When applying beamforming to transmit common control channels and signals, such a beam sweeping operation is necessary.

[0076] A terminal connecting to the system can acquire downlink frequency / time synchronization and cell ID information using a synchronization signal, and then acquire uplink synchronization through a random access procedure to form a radio link. In an NR system, an SS / PBCH (synchronization block / physical broadcast channel) block can also be transmitted using a beam sweeping method. An SS / PBCH block can be composed of PSS, SSS, PBCH, etc., and within an SS / PBCH block, the PSS, SSS, and PBCH can be composed using a time division multiplexing (TDM) method. An SS / PBCH block can also be referred to as an "SS block (SSB)." One SS / PBCH block can be transmitted using N consecutive OFDM symbols, where N can be an integer greater than or equal to 4. A base station can periodically transmit SS / PBCH blocks, and a terminal can acquire frequency / time synchronization, cell ID, system information, etc. based on the SS / PBCH block received from the base station. An SS / PBCH block can be transmitted as follows:

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

[0078] Referring to FIG. 5, one or more SS / PBCH blocks within an SS / PBCH block burst set may be transmitted using a beam sweeping scheme. Up to L SS / PBCH blocks may be transmitted within one SS / PBCH block burst set. L may be an integer greater than or equal to 2 and may be defined in the 3GPP standard. L may vary depending on the system frequency domain. Within an SS / PBCH block burst set, SS / PBCH blocks may be positioned contiguously or dispersedly. Contiguous SS / PBCH blocks may be referred to as an "SS / PBCH block burst." The SS / PBCH block burst set may be repeated periodically, and the system information (e.g., MIB) transmitted over the PBCH of the SS / PBCH blocks within the SS / PBCH block burst set may be identical. The SS / PBCH block index, SS / PBCH block burst index, OFDM symbol index, slot index, etc. may be indicated explicitly or implicitly by the PBCH.

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

[0080] Referring to FIG. 6, the arrangement order within an SS / PBCH block may be "PSS → PBCH → SSS → PBCH." Within an SS / PBCH block, the PSS, SSS, and PBCH may be configured in a TDM manner. In a symbol where the SSS is located, the PBCH may be arranged in a frequency resource higher than the SSS and a frequency resource lower than the SSS. When the maximum number of SS / PBCH blocks is 8 in a frequency band below 6 GHz, the index of the SS / PBCH block may be determined based on a demodulation reference signal (DMRS) (hereinafter referred to as "PBCH DMRS") used for PBCH demodulation. When the maximum number of SS / PBCH blocks is 64 in a frequency band above 6 GHz, the 3 least significant bits of the 6 bits indicating the index of the SS / PBCH block may be determined based on the PBCH DMRS, and the remaining 3 most significant bits may be determined based on the PBCH payload.

[0081] The maximum system bandwidth that can be supported in an NR system may be 400 MHz. The size of the maximum bandwidth that can be supported by a terminal may vary depending on the terminal's capability. Therefore, a terminal can perform an initial access procedure (e.g., an initial connection procedure) using a portion of the system bandwidth of an NR system that supports wideband. To support access procedures for terminals that support various sizes of bandwidth, SS / PBCH blocks can be multiplexed on the frequency axis within the system bandwidth of an NR system that supports wideband. In this case, the SS / PBCH blocks can be transmitted as follows:

[0082] FIG. 7 is a conceptual diagram illustrating a second embodiment of a method for transmitting SS / PBCH blocks in a communication system.

[0083] Referring to FIG. 7, a wideband component carrier (CC) can include multiple bandwidth parts (BWPs). For example, a wideband CC can include four BWPs. A base station can transmit an SS / PBCH block through each of BWPs #0 to #3 belonging to the wideband CC. A terminal can receive an SS / PBCH block through one or more BWPs among BWPs #0 to #3 and perform an initial access procedure using the received SS / PBCH block.

[0084] After detecting the SS / PBCH block, the UE can acquire system information (e.g., remaining minimum system information (RMSI)) and perform a cell access procedure based on the system information. The RMSI may be transmitted through a PDSCH scheduled by a PDCCH. Configuration information of a control resource set (CORESET) on which the PDCCH, including scheduling information for the PDSCH on which the RMSI is transmitted, may be transmitted through a PBCH within the SS / PBCH block. Multiple SS / PBCH blocks may be transmitted over the entire system bandwidth, and one or more SS / PBCH blocks among the multiple SS / PBCH blocks may be SS / PBCH blocks associated with the RMSI. The remaining SS / PBCH blocks may not be associated with the RMSI. The SS / PBCH block associated with the RMSI may be defined as a "cell-defining SS / PBCH block." The UE can perform a cell search procedure and an initial access procedure using the cell-defining SS / PBCH block. SS / PBCH blocks not associated with the RMSI may be used for synchronization and / or measurement procedures in the corresponding BWP. The BWP in which an SS / PBCH block is transmitted may be limited to one or more BWPs within a wide bandwidth.

[0085] The RMSI can be obtained by performing the following steps: acquire CORESET configuration information from the SS / PBCH block (e.g., PBCH) → detect PDCCH based on CORESET configuration information → acquire PDSCH scheduling information from PDCCH → receive RMSI through PDSCH. The PDCCH transmission resource can be configured according to the CORESET configuration information. The RMSI CORESET mapping pattern can be defined as follows: RMSI CORESET can be a CORESET used for transmitting and receiving RMSI.

[0086] FIG. 8a is a conceptual diagram illustrating RMSI CORESET mapping pattern #1 in a communication system, FIG. 8b is a conceptual diagram illustrating RMSI CORESET mapping pattern #2 in a communication system, and FIG. 8c is a conceptual diagram illustrating RMSI CORESET mapping pattern #3 in a communication system.

[0087] 8a to 8c, one RMSI CORESET mapping pattern may be used among RMSI CORESET mapping patterns #1-3, and detailed configuration may be completed according to one RMSI CORESET mapping pattern. In RMSI CORESET mapping pattern #1, the SS / PBCH block, CORESET (e.g., RMSI CORESET), and PDSCH (e.g., RMSI PDSCH) may be configured in a TDM manner. RMSI PDSCH may refer to a PDSCH through which RMSI is transmitted. In RMSI CORESET mapping pattern #2, the CORESET (e.g., RMSI CORESET) and PDSCH (e.g., RMSI PDSCH) may be configured in a TDM manner, and the PDSCH (e.g., RMSI PDSCH) may be configured with the SS / PBCH block in a frequency division multiplexing (FDM) manner. In RMSI CORESET mapping pattern #3, the CORESET (e.g., RMSI CORESET) and PDSCH (e.g., RMSI PDSCH) may be configured in a TDM manner, and the CORESET (e.g., RMSI CORESET) and PDSCH (e.g., RMSI PDSCH) may be configured with the SS / PBCH block in an FDM manner.

[0088] In frequency bands below 6 GHz, only RMSI CORESET mapping pattern #1 can be used. In frequency bands above 6 GHz, all of RMSI CORESET mapping patterns #1, #2, and #3 can be used. The numerology of the SS / PBCH block can be different from the numerology of "RMSI CORESET and RMSI PDSCH." Here, the numerology can be the subcarrier spacing. In RMSI CORESET mapping pattern #1, all numerology combinations can be used. In RMSI CORESET mapping pattern #2, the combination of "SS / PBCH block, RMSI CORESET / PDSCH = 120 kHz, 60 kHz or 240 kHz, 120 kHz" can be used. In RMSI CORESET mapping pattern #3, the combination of "SS / PBCH block, RMSI CORESET / PDSCH = 120 kHz, 120 kHz" can be used.

[0089] One RMSI CORESET mapping pattern can be selected from RMSI CORESET mapping patterns #1-3 according to the combination of the numerology of the SS / PBCH block and the numerology of the RMSI CORESET / PDSCH. RMSI CORESET configuration information can include Table A and Table B. Table A can indicate the number of RBs (resource blocks) of the RMSI CORESET, the number of symbols of the RMSI CORESET, and the offset between the RBs (e.g., start RB or end RB) of the SS / PBCH block and the RBs (e.g., start RB or end RB) of the RMSI CORESET. Table B can indicate the number of search space sets per slot, the offset of the RMSI CORESET, and the OFDM symbol index for each RMSI CORESET mapping pattern. Table B can indicate information for configuring the RMSI PDCCH monitoring occasion. Table A and Table B can each consist of multiple tables. For example, Table A may include Tables 13-1 to 13-8 specified in TS 38.213, and Table B may include Tables 13-9 to 13-13 specified in TS 38.213. The size of each of Table A and Table B may be 4 bits.

[0090] In an NR system, the PDSCH may be mapped to the time domain using PDSCH mapping type A or B. PDSCH mapping types A and B may be defined as shown in Table 1 below.

[0091] [Table 1]

[0092] Type A (i.e., PDSCH mapping type A) can be slot-based transmission. When Type A is used, the position of the starting symbol of the PDSCH can be set to one of {0, 1, 2, 3}. When Type A and normal CP are used, the number of symbols constituting the PDSCH (e.g., PDSCH duration) can be set to one of 3 to 14 within a symbol boundary. Type B (i.e., PDSCH mapping type B) can be non-slot-based transmission. When Type B is used, the position of the starting symbol of the PDSCH can be set to one of 0 to 12. When Type B and normal CP are used, the number of symbols constituting the PDSCH (e.g., PDSCH duration) can be set to one of {2, 4, 7} within a symbol boundary. A DMRS (hereinafter referred to as "PDSCH DMRS") for demodulating a PDSCH (e.g., data) may be determined based on an ID indicating a PDSCH mapping type (e.g., Type A, Type B) and length. The ID may be defined differently depending on the PDSCH mapping type.

[0093] With NR Phase 1 standardization completed in Rel-15 and Phase 2 standardization beginning in Rel-16, new features for the NR system are being discussed. One of the most prominent is NR-U (Unlicensed). NR-U is a technology that supports operation in unlicensed spectrum used for applications such as Wi-Fi to improve the utilization of limited frequency resources and increase network capacity. Standardization began with LTE-LAA (Licensed-Assisted Access) technology in Rel-13 and has continued to evolve through Rel-14 LTE-eLAA (Enhanced LAA) and Rel-15 LTE-feLAA (Further Enhanced LAA). Following the SI for NR-U, standardization work is also underway through WI in Rel-16.

[0094] In an NR-U system, a terminal can determine whether or not to transmit a signal from a base station based on a discovery reference signal (DRS) received from the base station, just like in a general NR system. In an NR-U system in stand-alone (SA) mode, a terminal can acquire synchronization and / or system information based on the DRS. In an NR-U system, the DRS can be transmitted according to unlicensed band regulations (e.g., transmission band, transmission power, transmission time, etc.). For example, according to the Occupied Channel Bandwidth (OCB) regulations, a signal can be configured and / or transmitted to occupy 80% of the entire channel bandwidth (e.g., 20 MHz).

[0095] In an NR-U system, a communication node (e.g., a base station or a terminal) can perform Listen Before Talk (LBT) before transmitting a signal and / or a channel to coexist with other systems. The signal can 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 can be a downlink channel, an uplink channel, a sidelink channel, etc. In the embodiments, a signal can refer to a "signal," a "channel," or a "signal and channel." LBT can be an operation to check whether a signal is being transmitted by another communication node. If the LBT determines that there is no transmission signal (e.g., if the LBT is successful), the communication node can transmit a signal in the unlicensed band. If the LBT determines that there is a transmission signal (e.g., if the LBT is unsuccessful), the communication node may not be able to transmit a signal in the unlicensed band. A communication node can perform LBT according to various categories before transmitting a signal. The LBT category can vary depending on the type of transmission signal.

[0096] Another representative feature of Rel-16 phase 2 is NR V2X (vehicular to everything). V2X is a technology that supports communication in various scenarios, such as vehicle-to-vehicle, vehicle-to-infrastructure, and vehicle-to-pedestrian, based on LTE D2D (Device-to-Device) communication. It has been much discussed in the LTE system and is still being developed. Discussions on NR V2X have also begun in NR with the launch of Rel-16.

[0097] NR V2X communication (e.g., sidelink communication) can be performed using three transmission methods (e.g., unicast, broadcast, and groupcast). When the unicast method is used, a PC5-RRC connection can be established between a first terminal (e.g., a transmitting terminal that transmits data) and a second terminal (e.g., a receiving terminal that receives data). The PC5-RRC connection can refer to a logical connection between a source ID of the first terminal and a destination ID of the second terminal. The first terminal can transmit data (e.g., sidelink data) to the second terminal. When the broadcast method is used, the first terminal can transmit data to all terminals. When the groupcast method is used, the first terminal can transmit data to a group (e.g., a groupcast group) consisting of multiple terminals.

[0098] When a unicast scheme is used, the second terminal may transmit feedback information (e.g., an acknowledgement (ACK) or a negative ACK (NACK)) for data received from the first terminal to the first terminal. In the following embodiments, the feedback information may be referred to as a "HARQ-ACK," a "feedback signal," a "physical sidelink feedback channel (PSFCH) signal," or the like. When an ACK is received from the second terminal, the first terminal may determine that the data has been successfully received by the second terminal. When a 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 a hybrid automatic repeat request (HARQ) scheme. Alternatively, the first terminal may retransmit the same data to the second terminal, thereby improving the probability of data reception by the second terminal.

[0099] When the broadcast method is used, the procedure for transmitting feedback information for data may not be performed. For example, system information may be transmitted in a broadcast manner, and the terminal may not transmit feedback information for the system information to the base station. Therefore, the base station may not know whether the terminal has successfully received the system information. To solve this problem, the base station may periodically broadcast system information.

[0100] When the groupcast method is used, the feedback information transmission procedure for data may not be performed. For example, necessary information may be periodically transmitted in the groupcast method without the feedback information transmission procedure. However, if the target and / or number of terminals participating in communication based on the groupcast method are limited and the data transmitted in the groupcast method is data that must be received within a predetermined time (e.g., delay-sensitive data), the feedback information transmission procedure may be required even in groupcast sidelink communication. Groupcast sidelink communication may refer to sidelink communication performed in the groupcast method. When the feedback information transmission procedure is performed in groupcast sidelink communication, data can be transmitted and received efficiently and stably.

[0101] Two HARQ-ACK feedback methods (i.e., feedback information transmission procedures) may be supported in groupcast sidelink communication. When there are many receiving terminals in a sidelink group and service scenario 1 is supported, some receiving terminals within a specific range in the sidelink group may transmit a NACK over the PSFCH if data reception fails. This method may be "groupcast HARQ-ACK feedback option 1." In service scenario 1, some receiving terminals within a specific range may be allowed to receive in a best-effort manner instead of all receiving terminals in the sidelink group. Service scenario 1 may be an extended sensor scenario in which some receiving terminals within a specific range need to receive the same sensor information from the transmitting terminal. In this embodiment, a transmitting terminal may refer to a terminal transmitting data, and a receiving terminal may refer to a terminal receiving data.

[0102] When the number of receiving terminals in a sidelink group is limited and service scenario 2 is supported, each receiving terminal in the sidelink group can individually report a HARQ-ACK for data via a separate PSFCH. This method may be referred to as "groupcast HARQ-ACK feedback option 2." Since PSFCH resources are sufficient in service scenario 2, the transmitting terminal can monitor the HARQ-ACK feedback of all receiving terminals in the sidelink group, ensuring data reception for all receiving terminals in the sidelink group. In all transmission methods, the application of the ACK / NACK feedback procedure can be configured statically or semi-statically in advance through system information and UE-specific RRC signaling, and can also be dynamically configured through control information.

[0103] In sidelink communication, ACK / NACK feedback information can be transmitted via the PSFCH. The PSFCH can be a channel used by a sidelink receiving terminal to report ACK / NACK information depending on whether the PSSCH is successfully received to a sidelink transmitting terminal. A resource region for PSFCH transmission can be pre-configured in a specific resource pool.

[0104] FIG. 9 is a conceptual diagram illustrating an example of setting PSFCH resources used for transmitting HARQ ACK / NACK information.

[0105] Referring to FIG. 9, the terminal can transmit the PSFCH in slot #n+12, which is a slot in which PSFCH transmission is possible after a preset sl-MinTimeGapPSFCH (e.g., 3 slots) from the time (slot) at which the terminal receives the PSSCH.

[0106] For example, the PSFCH may be configured to have a period of 1, 2, or 4 logical slots, and in a slot where PSFCH transmission is possible, the PSFCH may be transmitted repeatedly over two OFDM symbols, and the first symbol of the two OFDM symbols in which the PSFCH is transmitted may be used for AGC to adjust the PSFCH reception power level.

[0107] The PSFCH in the corresponding symbol may be transmitted within a frequency resource region preset by system information. In this case, the frequency resource region used for PSFCH transmission may be signaled in the form of a bitmap for the corresponding resource pool. The receiving terminal may implicitly select the frequency resource region in which the PSFCH is transmitted based on the slot index and subchannel index of the slot and subchannel in which the PSFCH is received. In addition, the index of the PSFCH resource for transmitting the PSFCH among the PSFCH resources that can be multiplexed by using a cyclic shift of the PSFCH sequence in a resource block (RB) within the corresponding frequency resource region may be implicitly selected based on a physical layer source ID and a member ID. In this case, the member ID is only used in the above-mentioned groupcast HARQ ACK / NACK feedback option 2, and may be set to 0 in other cases. The transmission time of the PSFCH may be determined as the first slot in which the PSFCH can be transmitted, occurring after a predetermined time (sl-MinTimeGapPSFCH) from the reception time of the PSSCH. The sl-MinTimeGapPSFCH may be preset to 2 or 3 slots, taking into account the time to process the received PSSCH and the time to prepare an ACK / NACK depending on whether the PSSCH was successfully received.

[0108] In addition, data reliability at the receiving terminal can be improved by appropriately adjusting the power of the transmitting terminal according to the transmission environment. Interference to other terminals can be mitigated by appropriately adjusting the power of the transmitting terminal. Energy efficiency can be improved by reducing unnecessary transmission power. Power control methods can be classified into open-loop power control methods and closed-loop power control methods. In open-loop power control methods, the transmitting terminal can determine the transmission power taking into account the configured and measured environment, etc. In closed-loop power control methods, the transmitting terminal can determine the transmission power based on a transmit power control (TPC) command received from the receiving terminal.

[0109] It can be difficult for a receiving terminal to predict the strength of a received signal due to various factors, including multipath fading channels and interference. Therefore, the receiving terminal can adjust the received power level (e.g., received power range) by performing automatic gain control (AGC) to prevent quantization errors in the received signal and maintain appropriate received power. In a communication system, a terminal can perform AGC 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, communication between terminals can be performed without a base station in sidelink communication. Therefore, performing AGC in sidelink communication can be difficult. In sidelink communication, a transmitting terminal can transmit a signal (e.g., a reference signal) to a receiving terminal before transmitting data. The receiving terminal can then adjust the received power range (e.g., received power level) by performing AGC based on the signal received from the transmitting terminal. The transmitting terminal can then transmit sidelink data to the receiving terminal. The signal used for AGC may be a duplicated signal of a subsequently transmitted signal or a signal previously set between the terminals.

[0110] The time interval required for AGC operation may be 15 μs. When the subcarrier spacing is 15 kHz in an NR system, the time interval (e.g., length) of one symbol (e.g., OFDM symbol) may be 66.7 μs. When the subcarrier spacing is 30 kHz in an NR system, the time interval (e.g., OFDM symbol) may be 33.3 μs. In the following examples, a symbol may refer to an OFDM symbol. That is, the time interval of one symbol may be more than twice the time interval required for AGC operation.

[0111] For sidelink communication, transmission of a data channel for data transmission and a control channel including scheduling information for data resource allocation may be required. In sidelink communication, the data channel may be a PSSCH (Physical Sidelink Shared CHannel), and the control channel may be a PSCCH (Physical Sidelink Control CHannel). The data channel and the control channel may be multiplexed in a resource domain (e.g., a time and frequency resource domain).

[0112] FIG. 10 is a conceptual diagram illustrating an embodiment of a method for multiplexing a control channel and a data channel in sidelink communication.

[0113] Referring to FIG. 10, sidelink communication can support Option 1A, Option 1B, Option 2, and Option 3. If Option 1A and / or Option 1B are supported, the control channel and the data channel can be multiplexed in the time domain. If Option 2 is supported, the control channel and the data channel can be multiplexed in the frequency domain. If Option 3 is supported, the control channel and the data channel can be multiplexed in both the time and frequency domains. Sidelink communication can basically support Option 3.

[0114] The basic unit of resource configuration in sidelink communication (e.g., NR-V2X sidelink communication) may be a subchannel. A subchannel may be defined by time and frequency resources. For example, a subchannel may consist of multiple symbols (e.g., OFDM symbols) in the time domain and multiple resource blocks (RBs) in the frequency domain. A subchannel may be referred to as an RB set. Within a subchannel, data channels and control channels may be multiplexed based on Option 3.

[0115] In sidelink communication (e.g., NR-V2X sidelink communication), transmission resources may be allocated based on Mode 1 or Mode 2. When Mode 1 is used, the base station may allocate sidelink resources for data transmission within a resource pool to a transmitting terminal, and the transmitting terminal may transmit data to a receiving terminal using the sidelink resources allocated by the base station. Here, the transmitting terminal may be a terminal that transmits data in sidelink communication, and the receiving terminal may be a terminal that receives data in sidelink communication.

[0116] When Mode 2 is used, the transmitting terminal can autonomously select sidelink resources to use for data transmission by performing resource sensing and / or resource selection within a resource pool. The base station can configure a resource pool for Mode 1 and a resource pool for Mode 2 to the terminal(s). 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.

[0117] When Mode 1 is used, the base station can schedule resources to be used for sidelink data transmission to the transmitting terminal, and the transmitting terminal can transmit sidelink data to the receiving terminal using the resources scheduled by the base station. Therefore, resource collisions between terminals can be prevented. When Mode 2 is used, the transmitting terminal can select any resource by performing a resource sensing operation and / or a resource selection operation, and can transmit sidelink data using any selected resource. Since the above procedures are performed based on the individual resource sensing operation and / or resource selection operation of each transmitting terminal, collisions between selected resources may occur.

[0118] Therefore, even when Mode 2 is used, a terminal (i.e., a coordinating terminal) can be configured to adjust resources for data transmission and reception between terminals, as in Mode 1, and notify terminals (i.e., coordinated terminals) that need to transmit and receive data of information about the adjusted resources (i.e., resource adjustment information), just like a base station in Mode 1. In this case, since the terminals perform data transmission and reception operations within the adjusted resources, collisions between resources can be prevented, and performance can be expected to improve accordingly. In addition, energy efficiency can be improved by the terminals performing sensing and selection operations within limited resources.

[0119] Hereinafter, a method and apparatus for transmitting resource coordination information in sidelink communication will be described. Even when a method (e.g., signal transmission or reception) performed by a first communication node among communication nodes is described, a corresponding second communication node can perform a method (e.g., signal reception or transmission) corresponding to the method performed by the first communication node. That is, when the operation of a transmitting terminal is described, the corresponding receiving terminal can perform an operation corresponding to the operation of the transmitting terminal. Conversely, when the operation of a receiving terminal is described, the corresponding transmitting terminal can perform an operation corresponding to the operation of the receiving terminal.

[0120] <Configuration and transmission method of resource adjustment information> Resource coordination information for data transmission between terminals and methods for transmitting resource coordination information can be classified into two methods: one is a method (Scheme 1) that provides information on candidate resources to assist in the operation of selecting resources to be used for actual data transmission and reception, and the other is a method (Scheme 2) that provides information on predicted or potential collisions that may occur on resources selected to be used for actual data transmission and reception.

[0121] In Scheme 1, a specific terminal (hereinafter, UE-A) can transmit information on candidate resources (resource coordination information) to another specific terminal (hereinafter, UE-B) to assist in resource selection. The UE-B can use the information on candidate resources for resource selection. In this case, the information on candidate resources may be information on preferred resources (preferred resource(s)) or information on non-preferred resources (non-preferred resource(s)). When information on preferred resources is provided, the UE-B preferably selects candidate resources to be preferentially used for data transmission from among the preferred resources indicated by the information. When information on non-preferred resources is provided, the UE-B preferably preferentially excludes non-preferred resources indicated by the information in candidate resource selection.

[0122] In Scheme 2, if a specific terminal (hereinafter referred to as UE-A) predicts a collision on a resource selected by a specific terminal (hereinafter referred to as UE-B) for data transmission and reception through SCI monitoring, it can provide information about the predicted collision (resource adjustment information) to the UE-B. In this case, the UE-B that receives the information can preferably select another resource instead of the resource where the collision is predicted to occur (i.e., resource reselection) to avoid the predicted collision.

[0123] Different criteria for selecting UE-A and UE-B may be applied for each method. For example, UE-A may be a terminal receiving data transmitted from UE-B. Furthermore, more than one UE-A or UE-B may be configured. In Mode 2 sidelink communication, whether Method 1 and Method 2 are supported may be configured in advance through system information, etc., and may be configured for each resource pool. When Method 1 is used, a method in which resource adjustment information is transmitted by explicit request or a method in which resource adjustment information is transmitted based on specific conditions other than an explicit request may be configured. Furthermore, it may be configured whether the transmitted resource adjustment information is information for preferred resources or non-preferred resources. Furthermore, a combination of these methods may be configured. For example, in the case of transmission of resource adjustment information based on an explicit request, it may be configured to transmit only information for preferred resources, to transmit only information for non-preferred resources, or to transmit either information for preferred resources or information for non-preferred resources. In addition, information on whether each scheme can be supported between terminals can be transmitted through UE-specific RRC signaling or PC5-RRC signaling, and can be set for each resource pool.

[0124] In method 1, UE-B receives resource coordination information for preferred or non-preferred resources for data transmission from UE-A and can use the received resource coordination information in the resource (re)selection process. Therefore, a method for accurately transmitting resource coordination information is required. Resource coordination information can be transmitted using SCI or MAC Control Element (CE), or both SCI and MAC CE. The transmission method of resource coordination information can be configured for each resource pool through system information, UE-specific RRC signaling, PC5-RRC signaling, or another MAC CE.

[0125] When the resource adjustment information is transmitted using the SCI, the resource adjustment information may be transmitted using the first stage SCI or the second stage SCI, or may be transmitted using both the first stage SCI and the second stage SCI. The first stage SCI may be transmitted over the PSCCH, and the second stage SCI or MAC CE may be transmitted over the PSSCH.

[0126] When resource adjustment information is transmitted using both the SCI and MAC CE, whether the resource adjustment information is transmitted through the SCI and / or MAC CE may be dynamically determined depending on the type of resource adjustment information (i.e., prioritized resource information or non-prioritized resource information) or the size of the resource adjustment information. Alternatively, the entire resource adjustment information may be transmitted overlappingly through both the SCI and MAC CE. Alternatively, the entire resource adjustment information may be transmitted separately through the SCI and MAC CE. More specifically, a portion of the resource adjustment information may be transmitted through the SCI, and the remaining portion may be transmitted through the MAC CE. In this case, a size criterion for the resource adjustment information may be preset to determine which container, SCI and / or MAC CE, the resource adjustment information is transmitted through. When the type of resource adjustment information determines whether the resource adjustment information is transmitted through one of the SCI and MAC CE, the type of resource adjustment information may be preset in the UE through system information, UE-specific RRC signaling, or PC5-RRC signaling. The type of resource coordination information can be transmitted in the form of a 1-bit indication included in the corresponding resource coordination information.

[0127] When selecting a prioritized resource or a non-prioritized resource in Method 1, UE-A can select a candidate resource for resource adjustment information based on received signal received power (RSRP) measured through a sensing process.

[0128] When UE-A provides information about prioritized resources, UE-A can exclude resources with measured RSRPs higher than a pre-set RSRP threshold based on priority. If the number of resources selected based on the set RSRP threshold does not meet the specific criteria for the prioritized resources to be provided, UE-A can increase the RSRP threshold and perform the process of selecting prioritized resources again. UE-A can repeatedly perform the process of selecting prioritized resources by continuously increasing the RSRP threshold until the number of selected resources meets the specific criteria for the prioritized resources to be provided. Alternatively, since resource adjustment information is used as auxiliary information for UE-B's resource selection, the number of selected prioritized resources may not necessarily meet the specific criteria. Therefore, UE-A can perform the process of selecting prioritized resources by increasing the RSRP threshold up to a predetermined RSRP upper limit.

[0129] Even when UE-A provides information about non-prioritized resources, UE-A can select non-prioritized resources based on the RSRP measurement results. In this case, unlike the case of selecting prioritized resources, UE-A can select resources whose measured RSRP is higher than a predetermined RSRP threshold as non-prioritized resources. In this case, UE-A can repeatedly perform the process of reducing the RSRP threshold and selecting non-prioritized resources until the number of selected non-prioritized resources meets a specific criterion for non-prioritized resources to be provided. As another method, UE-A can reduce the RSRP threshold to a predetermined RSRP lower limit and perform the process of selecting non-prioritized resources.

[0130] In the existing sidelink scheduling scheme, up to three resources can be scheduled or reserved through a combination of information on a time domain slot index (Time Resource Indication Value, TRIV) and information on a frequency domain subchannel index (Frequency Resource Indication Value, FRIV) depending on the configuration. In this case, the number of resources that can be scheduled and reserved through the TRIV / FRIV combination can be configured in the UE through system information, UE-specific RRC signaling, or PC5-RRC signaling so that signaling of a large number of possible resources is possible. Alternatively, the number of resources that can be scheduled and reserved through the TRIV / FRIV combination may be fixed to a maximum value of three. Meanwhile, information on a resource reservation period can be additionally signaled in addition to the TRIV / FRIV combination. Therefore, a scheme that extends the existing sidelink scheduling scheme by N times can be used to provide resource coordination information. For example, the number of resources that can be provided through resource coordination information can be up to N*3.

[0131] In existing scheduling methods based on TRIV / FRIV combinations, the slot index and starting subchannel index for the first resource are set by the slot index and starting subchannel index in which the PSCCH containing the corresponding scheduling information is received, and are therefore not separately signaled. However, for resource coordination information, separate signaling of the slot index and subchannel index of the first resource may be required. That is, signaling of the slot index (or slot offset) and starting subchannel index for the first resource may be required for each of the N TRIV / FRIV combinations. In this case, time and frequency axis information for the first resource of each of the N combinations may be signaled individually or in combination.

[0132] FIG. 11 is a conceptual diagram for explaining a first embodiment of a signaling method for resource adjustment information according to the present invention.

[0133] 11, within a time period for signaling, information for N TRIV / FRIV combinations may be sorted and signaled in the time order of the first resource. Preferably, the resources signaled for the N TRIV / FRIV combinations are selected so as not to overlap with each other.

[0134] When individual signaling is used, time domain resource information and frequency domain resource information for each of the N first resources #0, #1, and #N-1 must be signaled. The signaling for time domain resource information (i.e., the first slot index or slot offset) may be limited to a portion of time resources located before the target time interval for selecting a preferred or non-prioritized resource. However, the signaling for frequency domain resource information (i.e., the starting subchannel index or subchannel offset) requires signaling for the entire frequency domain resource range without such limitations, which may result in relatively large signaling overhead. Therefore, the signaling range of frequency domain resource information may also be limited. The signaling range for time and frequency domain resource information may be pre-configured or pre-defined in the UE through system information, UE-specific RRC signaling, or PC5-RRC signaling. In this case, the signaling range for time domain resource information and frequency domain resource information may be set to be different from each other depending on the container(s) used to transmit resource coordination information. Specifically, when resource coordination information is transmitted through both SCI and MAC CE, the same information is transmitted through both SCI and MAC CE, so the signaling range can be set small in consideration of the SCI having a relatively small number of bits. On the other hand, when resource coordination information is transmitted only through MAC CE, a relatively large number of bits can be used, so the signaling range can be set larger. As another method, frequency domain resource information does not need to be signaled separately. In this case, since information on the starting subchannel index for the first resource is unknown, it is possible to signal a number of resources that is less than the maximum number of resources that can be scheduled and reserved in the TRIV / FRIV combination. That is, if up to M resources can be scheduled and reserved, M-1 resources can be signaled.

[0135] As another method for individual signaling, time domain resource information and frequency domain resource information for resource #0 among the first N resources #0, #1, and #N-1 may be signaled, and time domain resource information for resources after resource #1 may be signaled as an offset relative to resource #0. As described above, if the first resource of N TRIV / FRIV combinations is sorted chronologically, the time domain resource information for the first resource of the remaining N-1 resources may be signaled by applying only a '+' offset based on the time domain resource information of resource #0. If resource selection at the same time is allowed, an offset of '0' may also be included in the time domain resource information. Frequency domain resource information for the first resource of the remaining N-1 resources may be signaled as a + / - offset including '0'. As another method for signaling frequency domain resource information, a scheme may be used in which only a '+' offset including '0' is used and the total number of subchannels and the offset are modulo-operated. In this case, the ranges of the time domain offset and the frequency domain offset may be preset through system information, UE-specific RRC signaling, or PC5-RRC signaling. The time domain resource information and the frequency domain resource information for resource #0 may also be signaled as offsets, like the other first resources #1, #2, and #N-1. In this case, separate time domain references and frequency domain references for resource #0 may be required.

[0136] As another method for individual signaling, offset-based signaling of time domain resource information and frequency domain resource information may be applied within a wider range only to the first resource #0 among N first resources #0, #1, and #N-1, and offset-based signaling of time domain resource information and frequency domain resource information may be applied within a limited range to the remaining first resources #1, #2, and #N-1, in which case, a separate time domain reference and frequency domain reference for resource #0 may still be required.

[0137] Alternatively, time domain resource information and frequency domain resource information for resource #0 among the N first resources #0, #1, and #N-1 can be signaled, and subsequent resources can be signaled in a chain form using TRIV / FRIV combinations.

[0138] FIG. 12 is a conceptual diagram for explaining a second embodiment of the resource adjustment information signaling method according to the present invention.

[0139] 12, time domain resource information and frequency domain resource information for resource #0 corresponding to the first resource of the first combination among N TRIV / FRIV combinations may be signaled separately, and the last resource of the first TRIV / FRIV combination may be signaled as the first resource of the second TRIV / FRIV combination. When such signaling is used, signaling overhead may be reduced because only time domain resource information and frequency domain resource information for resource #0 among the N first resources #0, #1, and #N-1 need to be signaled.

[0140] In the above procedure, a reference slot may be required for time domain resource information for N initial resources #0, #1, and #N-1 or for time domain resource information for the first resource #0 of the N initial resources. When time domain resource information is provided as a slot index or slot offset, the reference slot may be a slot that serves as a reference for the corresponding information. The reference slot may be set as a slot in which resource coordination information is transmitted, and information for the reference slot may be transmitted through the resource coordination information separately from the time domain resource information.

[0141] When the reference slot is set as the slot in which resource adjustment information is transmitted, the reference slot may be time domain resource information for the first resource #0 among the N first resources #0, #1, and #N-1, and the time domain resource information for the remaining first resources #1 to #N-1 may be expressed as slot offsets relative to the reference slot.

[0142] When information about the reference slot is transmitted separately through resource coordination information, the information may be composed of a combination of a frame number such as SFN or DFN and a slot index within the frame. Also, a reference subchannel index for frequency domain resource information for the first N resources (#0, #1, ..., #N-1) or for the first resource #0 of the N resources may be required. In this case, the reference subchannel index may be subchannel index #0 within the corresponding resource pool or the lowest subchannel index of the frequency resource for which resource coordination information is transmitted. Alternatively, a specific subchannel index within the corresponding resource pool may be indicated as the reference subchannel index through the resource coordination information, separately from the frequency domain resource information.

[0143] When configuring resource coordination information based on the TRIV / FRIV combination, the number of subchannels indicated by FRIV (e.g., N sub ) is the number of sub-channels (e.g., N sub,req ), then N sub Smaller than N sub,req All of the consecutive subchannels can be selected as individual candidate resources for data transmission. For example, sub,req = 3, and through FRIV start subchannel index = 1 and N sub If =5 is signaled, then subchannels {1, 2, 3}, subchannels {2, 3, 4}, or subchannels {3, 4, 5} may all be indicated as individual candidate resources for data transmission.

[0144] As described above, even if resource coordination information can be transmitted with N TRIV / FRIV combinations, the number of TRIV / FRIV combinations that can actually be signaled may be less than N. However, if the size of the overall resource coordination information varies depending on the number of TRIV / FRIV combinations that can actually be signaled, the reception complexity of the terminal receiving this information may increase. Therefore, regardless of the number of TRIV / FRIV combinations that can actually be signaled, the size of the overall resource coordination information may be kept constant, and information regarding the number of TRIV / FRIV combinations (≦N) that are actually signaled may be separately added to the corresponding information.

[0145] <Priority of resource adjustment information transmission> In Scheme 1, resource adjustment information can be transmitted from UE-A to UE-B at the explicit request of UE-B or under specific predefined conditions. When resource adjustment information is transmitted at the explicit request of UE-B, the request message of UE-B can be transmitted through the first-phase SCI, second-phase SCI, or MAC CE. The same request message can be transmitted simultaneously through the second-phase SCI and MAC CE, or through a combination of the second-phase SCI and MAC CE. In this case, which container(s) the request message is transmitted through can be set for each resource pool through system information, UE-specific RRC signaling, PC5-RRC signaling, or another MAC CE.

[0146] When a request message is transmitted simultaneously through the second-stage SCI and MAC CE, the same information may be transmitted through the second-stage SCI and MAC CE, and the corresponding SCI and / or MAC CE may include a 1-bit indicator for distinguishing whether the information is a request message or resource coordination information. When a request message is transmitted through a combination of the second-stage SCI and MAC CE, a 1-bit indicator for resource coordination information request may be transmitted through the corresponding SCI, and additional request-related information may be transmitted through the MAC CE. Regardless of whether the request message is transmitted through the second-stage SCI and / or MAC CE, the request message may include a priority value for PSCCH and PSSCH transmission, the number of subchannels, and resource reservation cycle information for periodic transmission. In this case, the priority value may be referenced during UE-A's resource coordination information selection process. Furthermore, when UE-A transmits resource coordination information to UE-B, the priority for resource coordination information transmission may be applied. In addition, the request message may include information on the start time and end time for setting a period (resource selection period) in which prioritized / non-prioritized resources for resource coordination information are selected, or information on the end time only. UE-A can set the resource selection period for resource coordination information based on the corresponding information, which may be composed of a specific frame number (SFN or DFN) and a slot index within a specific frame. The request message may also include information indicating whether the requested resource coordination information is prioritized resource information or non-prioritized resource information. When resource coordination information is transmitted according to specific conditions rather than by a request message, the information may be pre-configured through system information, UE-specific RRC signaling, and / or PC5-RRC signaling, etc.

[0147] As described above, which container(s) the resource coordination information and request message are transmitted through (e.g., whether they are transmitted only through the MAC CE or through both the MAC CE and the second stage SCI) can be configured for each resource pool through system information, UE-specific RRC signaling, PC5-RRC signaling, or another MAC CE. In this case, it is preferable to simultaneously apply the corresponding configuration to the resource coordination information and the request message rather than individually applying the corresponding configuration to each of them in terms of signaling overhead efficiency. That is, if configured to be transmitted only through the MAC CE, the resource coordination information and request message are all transmitted only through the MAC CE, and if configured to be simultaneously transmitted through the second stage SCI and the MAC CE, the resource coordination information and request message can all be transmitted simultaneously through the second stage SCI and the MAC CE.

[0148] As described above, when resource coordination information is transmitted by an explicit request message from the UE-B or under specific conditions, the priority of the resource coordination information may be set through system information, UE-specific RRC signaling, PC5-RRC signaling, etc. If the resource coordination information is transmitted by a request message when the corresponding priority is not set, the priority (priority value) included in the request message or the priority of the request message may be set as the priority of the resource coordination information. If the resource coordination information is transmitted under specific conditions when the corresponding priority is not set, the UE may concretely set the priority of the resource coordination information. If the resource coordination information is multiplexed and transmitted with other data, the priority of the resource coordination information may be compared with the priority of the data and a higher priority may be applied. In the above procedure, the priority is determined by a priority value, and a higher priority value means a lower priority (the highest priority value means the lowest priority). As described above, based on the set priority, the UE may determine whether to transmit the corresponding resource coordination information through a conventional priority comparison procedure between the uplink and sidelink or a priority comparison procedure between the LTE sidelink and NR sidelink. When resource coordination information is received, the priority of the corresponding resource coordination information can be determined based on priority information included in the SCI that schedules the PSSCH including the corresponding resource coordination information.

[0149] When UE-A transmits resource coordination information to UE-B, a source ID and a destination ID for the transmission of the resource coordination information may be required. If the sidelink communication between UE-A and UE-B is unicast communication or managed groupcast communication in which the transmitting terminal knows information for the receiving terminal, and the UE-A transmits the resource coordination information based on an explicit request from UE-B, UE-A can use the source ID and destination ID used in the UE-B request message transmission for the resource coordination information transmission. That is, the source ID and destination ID of the UE-B request message can be applied as the destination ID and source ID, respectively, for the UE-A resource coordination information transmission. In addition, if the resource coordination information request message is a request for a terminal other than UE-B or if the sidelink communication between UE-A and UE-B is not unicast or managed groupcast communication, it is preferable that the source ID and destination ID for the corresponding terminal be included in the request message. When resource adjustment information is transmitted under a specific condition, it is preferable that the source ID and the destination ID are set in advance.

[0150] <Resource Adjustment Information Feedback / Retransmission> After UE-B transmits a request message for resource adjustment information, UE-B can receive the corresponding resource adjustment information within a certain time (e.g., Tci, 1). If UE-B fails to receive the resource adjustment information within a certain time, or if the request message is transmitted through the PSSCH (e.g., the request message is transmitted to the MAC CE) but a NACK for the corresponding PSSCH is fed back to UE-B (when HARQ ACK / NACK feedback is activated), UE-B can request the maximum requestable time (e.g., T) depending on the data transmission time (e.g., PDB, Packet Delay Budget), etc. bound,1In addition, if UE-B fails to receive resource coordination information within a certain time (for example, if the transmission of PSSCH including resource coordination information is confirmed through SCI but the decoding of the resource coordination information fails), and if HARQ ACK / NACK feedback is activated, UE-B can transmit NACK feedback for the corresponding PSSCH (resource coordination information) instead of retransmitting the request message.

[0151] Meanwhile, UE-A waits a certain time (e.g., T ci,2 ) within the maximum transmission time (e.g., when the resource coordination information is transmitted to the MACK CE) and NACK feedback is received for the corresponding PSSCH (resource coordination information), the UE-A can retransmit the resource coordination information. Even if the UE-A receives NACK feedback, the retransmission time of the resource coordination information may be longer than the maximum transmission time (e.g., when the resource coordination information is transmitted to the MACK CE). Tbound,2 ), UE-A may not retransmit the resource adjustment information. ci,1 , T ci,2 , T bound,1 , and T bound,2 may be set to be different from each other, and some of them (e.g., T ci,1 and T ci,2 or Tbound,1 and T bound,2 ) or the whole may be set to the same value. ci,1 , T ci,2 , T bound,1 , and T bound,2 can be set through system information, UE-specific RRC signaling, or PC5-RRC signaling, or the corresponding value can be applied as a timer value. For example, T ci,2A timer for can be started, and UE-A can transmit resource adjustment information before the corresponding timer expires. Even when the transmission of resource adjustment information is performed based on specific conditions, the above-mentioned fixed time or timer can be equally applied to the transmission, reception, and retransmission operations of resource adjustment information. In all the above cases, transmission resources for performing the transmission or retransmission of resource adjustment information must be ensured. If the transmission resources are not ensured within the maximum transmission possible time, UE-A can cancel the corresponding resource adjustment information transmission.

[0152] Scheme 2 is a method in which UE-B receives information on predicted or potential collisions from UE-A as resource adjustment information before transmitting data and performs a resource reselection operation to avoid resources where collisions are expected. Therefore, in Scheme 2, it is preferable that the reception procedure of resource adjustment information is not complicated. Therefore, the resource adjustment information according to Scheme 2 is preferably transmitted using the PSFCH used for existing HARQ ACK / NACK transmission. Different from the PSFCH (hereinafter, "AN-PSFCH" or "AN-PSFCH") including HARQ ACK / NACK for the PSSCH described with reference to FIG. 9, the PSFCH (hereinafter, "CI-PSFCH" or "CI-PSFCH") for transmitting the resource adjustment information (hereinafter, conflict indication) according to Scheme 2 can be used for the resource reselection operation for PSSCH transmission. Therefore, the PSFCH for transmitting the conflict indication according to Scheme 2 must be transmitted before UE-B transmits the PSSCH.

[0153] Therefore, the embodiments of the present invention propose the time point when UE-B transmits "CI-PSFCH" before transmitting the PSSCH, the resource selection method for transmitting "CI-PSFCH", and the transmission method of "CI-PSFCH".

[0154] <Determination of CI-PSFCH Transmission Time Point> As described above, unlike the AN-PSFCH, the CI-PSFCH must be transmitted before the UE-B transmits the PSSCH, so it is necessary to set an appropriate time point for transmitting the CI-PSFCH.

[0155] To generate a collision indication, UE-A monitors multiple SCIs, including UE-B's SCI, and if the resources (subchannel(s)) predicted to be used by UE-B overlap (in whole or in part) (one or more subchannels or RBs constituting a subchannel) with the resources (subchannel(s)) predicted to be used by another terminal (e.g., UE-C), it can predict a collision for the resources predicted to be used by UE-B and transmit a collision indication to UE-B. In this case, UE-A measures the RSRP for the resources (resources predicted to be used by UE-B) and predicts a collision for the resources if the measured RSRP is greater than the RSRP threshold value according to the priority information of UE-B or the priority information in the SCI of the other terminal (e.g., UE-C) or a preset RSRP threshold value. Alternatively, UE-A can predict a collision for the resources (resources predicted to be used by UE-B) if the measured RSRP is within a preset RSRP range. Alternatively, if the distance between UE-B and UE-C determined based on the SCI of UE-B to UE-C is within a predetermined distance, UE-A can predict a collision for the corresponding resource. Alternatively, various criteria for determining resource collision may be predefined, and at least some of these may be configured in the UE through system information or UE-specific RRC signaling, and may be configured for each resource pool.

[0156] As described above, the transmission time of the CI-PSFCH transmitting information about a predicted collision can be set based on the slot in which the SCI used to predict the collision (i.e., the SCI transmitted by the UE-B) is transmitted, or based on the slot in which the PSSCH in which the collision is predicted to occur is scheduled to be transmitted. Determining the transmission time of the CI-PSFCH based on the slot in which the SCI used to predict the collision is transmitted allows for earlier signaling. Generally, since multiple PSSCH resources can be reserved by one SCI (hereinafter, for convenience, the first SCI), predicted collisions for PSSCH resources scheduled for future use can be signaled earlier. However, collisions can be determined through monitoring not only the first SCI but also other SCIs (hereinafter, the second SCI). Therefore, if resource coordination information (information about a predicted collision) is signaled at a time determined based on the first SCI, prediction information about collisions that may occur due to the second SCI(s) transmitted after the corresponding time is not provided, and significant performance improvements are unlikely to be achieved. In addition, when multiple reserved resources are signaled by the first SCI, information regarding which of the multiple resources the collision occurs with must be additionally signaled, which may increase signaling overhead. On the other hand, if the time to transmit resource coordination information is determined based on the slot in which the PSSCH in which a collision is predicted is transmitted, the signaling delay may increase, but better performance can be expected because collision information can be predicted based on monitoring results for a larger number of second SCIs. In addition, even if multiple resources are signaled by the first SCI, resource coordination information is signaled at the time when it is determined based on the location of the resource in which an actual collision is predicted, so there is no need to separately signal which resource the predicted collision occurs with.

[0157] As described above, there may be advantages and disadvantages depending on whether the transmission time of the CI-PSFCH is determined based on the slot in which the SCI used to predict the collision is transmitted or the slot in which the PSSCH predicted to cause a collision is transmitted. Therefore, which of the two methods is selected may be set for each resource pool through system information, UE-specific RRC signaling, MAC CE, etc. depending on various system conditions.

[0158] Hereinafter, one embodiment of the present invention proposes a method for determining the time to transmit the CI-PSFCH based on the slot in which the PSSCH, where collision is predicted to occur, is transmitted. Unlike the AN-PSFCH, which is transmitted after receiving the PSSCH, the CI-PSFCH must be transmitted from UE-A to UE-B before UE-B transmits the PSSCH. In this case, it is preferable to determine the time to transmit the CI-PSFCH from UE-A, taking into consideration the processing time required for UE-B to receive and process the CI-PSFCH and the processing time required for UE-B to perform resource reselection based on the information of the received CI-PSFCH. Therefore, it is preferable to determine the time to transmit the CI-PSFCH from UE-A, taking into consideration the processing time. min ) is set, and the time of transmitting the CI-PSFCH is set to T from the slot in which the PSSCH is transmitted, where a collision is predicted. min A method is proposed in which the nearest (latest) slot among slots in which the CI-PSFCH can be transmitted (i.e., CI-PSFCH transmission slots) is determined. In this case, T min The value of may be configured through system information, UE-specific RRC signaling, and / or MAC CE.

[0159] FIG. 13 is a conceptual diagram illustrating an embodiment of a method for determining a transmission time point of a CI-PSFCH based on a slot in which a PSSCH in which collision is predicted to occur is transmitted.

[0160] Referring to FIG. 13, the slot in which the resources reserved for PSSCH transmission are located is slot #k, and T min It can be assumed that UE-A is configured with 3 slots and the period for CI-PSFCH transmission slots is configured with 4 slots. min ) or earlier, the CI-PSFCH can be transmitted to UE-B through slot #(n+12), which is the nearest (latest) slot among the CI-PSFCH transmission slots. UE-B can monitor the CI-PSFCH in slot #(n+12), which is determined based on slot #k reserved for PSSCH transmission. UE-B can acquire resource adjustment information in slot #(n+12), which indicates that PSSCH transmission performed in slot #k is expected to collide with PSSCH transmission of another terminal (e.g., UE-C), and can perform resource reselection based on the resource adjustment information and transmit the PSSCH using the other selected resource. In FIG. 13, T min An example where T was set to 3 was explained. min The value of T3 (=T) is the time point at which re-evaluation of the selected resource is allowed before actual sidelink data transmission is performed using the resource selected through the release-16 sidelink resource selection process. proc,1 SL ) or T3 or more. In addition, the processing time required for UE-A to judge collision prediction after receiving the SCI is T min,2 It is preferable to transmit the CI-PSFCH after that. In this case, T min,2 The value can be set to be equal to sl-MinTimeGapPSFCH (described with reference to FIG. 9), which is the minimum time interval for transmitting HARQ ACK / NACK information for a PSSCH received after receiving a PSSCH in the existing release-16 sidelink. Alternatively, since the CI-PSFCH does not need to determine whether data reception is successful, unlike the AN-PSFCH, T min,2 The value is shorter than sl-MinTimeGapPSFCH. proc,0SL The resource coordination information in Method 2 is information regarding collisions predicted in a slot in which the PSSCH is transmitted, and does not include information regarding frequency-domain subchannels for PSSCH transmission within the slot. Therefore, when performing resource reselection, the UE-B preferably selects resources in slots other than the corresponding slot. More specifically, during the resource reselection process, the UE-B preferably excludes subchannels corresponding to slots in which collisions are predicted according to the resource coordination information from candidate resources for resource reselection. If resource coordination information is transmitted at the time of determination based on the slot in which the PSSCH is transmitted, it may be possible to determine which reserved resource is predicted to cause a collision even if multiple resources are reserved by the SCI. Therefore, immediately after receiving the resource coordination information, the UE-B may exclude subchannel(s) belonging to the slot in which the PSSCH is reserved from candidate resources for resource reselection. Even in this case, the UE-B may exclude subchannel(s) corresponding to not only the slot in which the PSSCH is transmitted and in which collisions are predicted, but also the slot(s) including all of its reserved resources from candidate resources for resource reselection. Alternatively, the UE-B may determine that the collision indicated by the received resource coordination information is limited to the subchannel(s) reserved for PSSCH transmission within the corresponding slot(s) (the immediately following reserved resource slot or the slot(s) including all reserved resources), and exclude only resources overlapping with the corresponding subchannel(s) from the candidate resources. The above procedure may be configured for each resource pool via system information, UE-specific RRC signaling, PC5 RRC signaling, MAC CE, etc.

[0161] Hereinafter, a method for transmitting the CI-PSFCH when the time to transmit the CI-PSFCH is determined based on the slot in which the SCI used to predict collision is transmitted will be described. When the CI-PSFCH is transmitted at a time determined based on the slot in which the SCI used to predict collision is transmitted, it is preferable that the UE-B transmits the CI-PSFCH after a certain processing time has elapsed since the time the SCI is received. Therefore, a minimum time gap (T min,2 ) can be set, and UE-B can set the CI-PSFCH to the corresponding T min,2 After that, the CI-PSFCH can be transmitted in the nearest (earliest) slot among the slots in which the CI-PSFCH can be transmitted. min,2 The value of can be set through system information, UE-specific RRC signaling, or MAC CE.

[0162] FIG. 14 is a conceptual diagram illustrating an embodiment of a method for determining a transmission time point of a CI-PSFCH based on a slot in which an SCI used for collision prediction is transmitted.

[0163] Referring to Figure 14, T min,2 It can be assumed that the period of the CI-PSFCH transmission slot is set to 3 slots and the period of the CI-PSFCH transmission slot is set to 4 slots. When a PSCCH including an SCI is transmitted in slot #m and a collision is expected with the resources of slot #k reserved through the corresponding SCI, UE-A transmits the PSCCH from slot #m to m+T. min,2 The CI-PSFCH can be transmitted to UE-B in slot #n+8, which is the nearest (earliest) CI-PSFCH transmission slot in the slot or a subsequent time interval. UE-B can monitor the CI-PSFCH in slot #n+8. UE-B acquires resource coordination information in slot #n+8 indicating that PSSCH transmission performed in slot k is expected to collide with PSSCH transmission of another terminal (e.g., UE-C), and can perform resource reselection based on the resource coordination information and transmit the PSSCH using the selected other resource. In FIG. 14, Tmin,2 An example where T was set to 3 was explained. min,2 The value of can be set to be equal to sl-MinTimeGapPSFCH, which is the minimum time interval for transmitting HARQ ACK / NACK information for the received PSSCH, as described with reference to Figure 9. Unlike the AN-PSFCH, the CI-PSFCH does not need to determine whether data reception is successful. min,2 The value is shorter than sl-MinTimeGapPSFCH. proc,0 SL In addition, in order for UE-B to receive the CI-PSFCH and perform resource reselection based on the received CI-PSFCH, the CI-PSFCH must be received at least T before slot k where actual collision is expected. min In this case, it is preferable that the signal is received before the time interval T min The value of T3 (=T) is the time point at which re-evaluation of the selected resource is allowed before actual sidelink data transmission is performed using the resource selected through the release-16 sidelink resource selection process. proc,1 SL) or T3 or greater. The resource coordination information in Method 2 is information regarding collisions predicted in a slot in which the PSSCH is transmitted, and does not include information regarding frequency-domain subchannels for PSSCH transmission within the slot. Therefore, when performing resource reselection, the UE-B preferably selects resources in a slot other than the corresponding slot. More specifically, during the resource reselection process, the UE-B preferably excludes subchannels belonging to slots in which collisions are predicted according to the resource coordination information from candidate resources for resource reselection. When multiple resources are reserved by the SCI, the resource coordination information may not include additional information regarding which reserved resources are predicted to cause collisions. In this case, the UE-B may exclude subchannel(s) belonging to the reserved resource slot immediately after receiving the corresponding resource coordination information from candidate resources for resource reselection. Alternatively, the UE-B may exclude subchannel(s) belonging to a slot(s) including all reserved resources from candidate resources for resource reselection. Alternatively, the UE-B may determine that the collision indicated by the received resource coordination information is limited to the subchannel(s) reserved for PSSCH transmission within the corresponding slot(s) (the immediately following reserved resource slot or the slot(s) including all reserved resources) and exclude only resources overlapping with the corresponding subchannel(s) from the candidate resources. The above procedure may be configured for each resource pool through system information, UE-specific RRC signaling, PC5 RRC signaling, MAC CE, etc.

[0164] When transmitting CI-PSFCH as described above, if the transmission period of AN-PSFCH for transmitting HARQ ACK / NACK feedback information for the PSSCH received in slot m is set to be the same as the transmission period of CI-PSFCH, then CI-PSFCH and AN-PSFCH can always be transmitted in the same slot. Therefore, in order to avoid this, the transmission periods of CI-PSFCH and AN-PSFCH can be set to be different from each other. Or the transmission periods of CI-PSFCH and AN-PSFCH are set to be the same, and an offset can be applied between the CI-PSFCH transmission slot and the AN-PSFCH transmission slot. When CI-PSFCH and AN-PSFCH are always transmitted in the same slot, CI-PSFCH or SFCH-for-AN can be transmitted by the AN-PSFCH priority determination method between CI-PSFCHs described later.

[0165] In FIG. 13 or FIG. 14, in order for UE-B to newly select resources based on the resource adjustment information, CI-PSFCH should be received at least before the time interval T min (≧T3). If the minimum time interval cannot be guaranteed, UE-A can drop the CI-PSFCH transmission.

[0166] <CI-PSFCH Transmission Resource Determination> Similar to AN-PSFCH, the transmission resource setting of CI-PSFCH is necessary. Therefore, the method for setting the transmission resources of CI-PSFCH will be described below.

[0167] For example, in the case of AN-PSFCH transmission, the frequency domain for transmitting and receiving the AN-PSFCH, the resource period, the number of cyclic shift pairs that can be multiplexed within one RB, the number of AN-PSFCH resources onto which HARQ ACK / NACK information can be multiplexed, and the scrambling ID for sequence hopping of the AN-PSFCH can be configured. In order to reduce signaling overhead, the transmission period of the CI-PSFCH is not separately configured, but is preferably set to the same as the transmission period of the AN-PSFCH. Furthermore, the number of cyclic shift pairs that can be multiplexed within one RB is not separately configured, but is preferably set to the same value as the value configured for the AN-PSFCH or is always fixed to 1. The number of CI-PSFCH resources onto which collision indication information, as well as HARQ ACK / NACK information, can be multiplexed is preferably set to the same value as the number of AN-PSFCH resources or is always fixed to 1. It is preferable that the scrambling ID for sequence hopping of the CI-PSFCH also uses the same value as that of the AN-PSFCH or is always fixed to 0. Alternatively, when the AN-PSFCH and the CI-PSFCH are transmitted in the same resource region, the scrambling ID for sequence hopping of the CI-PSFCH can be set separately to reduce interference with the AN-PSFCH sequence.

[0168] The AN-PSFCH is transmitted in the last two symbols of the AN-PSFCH transmission slot, and its frequency domain can be configured through RB-based bitmap signaling in the corresponding resource pool. Therefore, the CI-PSFCH, which has the same transmission period as the AN-PSFCH, is transmitted in the same slot and the same symbol as the AN-PSFCH, and the frequency domain of the CI-PSFCH can be configured differently from the frequency domain of the AN-PSFCH to reduce signaling overhead. In this case, the frequency domain resource of the CI-PSFCH can be implicitly configured to be a resource other than the frequency domain configured for transmission of the AN-PSFCH in the corresponding slot. Alternatively, the frequency domain resource of the CI-PSFCH can be configured through separate RB-based bitmap signaling in the same manner as the AN-PSFCH.

[0169] In the CI-PSFCH resource region set through such parameter signaling, as described above, the transmission time of the CI-PSFCH can be determined based on the slot in which the PSSCH for which collision is predicted is transmitted. The CI-PSFCH resource at that time can be selected based on the index of the slot in which the PSSCH for which collision is predicted is transmitted and the subchannel index. The PSFCH index actually used within the selected CI-PSFCH resource is preferably set based on the physical layer source ID (P_ID) indicated by the SCI of the UE-B. If an ID for the receiving terminal (e.g., Member ID (M_ID)) is additionally set from a higher layer, the ID for the receiving terminal can also be applied. If an ID for the receiving terminal is not additionally set, the corresponding value can be fixed to 0. Furthermore, when there are one or more subchannels for transmitting the PSSCH for which collision is predicted, the index of the first subchannel among the one or more subchannels (i.e., the smallest subchannel index) is preferably used as the subchannel index for selecting the CI-PSFCH resource.

[0170] The information transmitted and received via the CI-PSFCH may be information indicating that collision is predicted in the resource on which the UE-B's PSSCH is transmitted (i.e., collision prediction information). Alternatively, the information transmitted and received via the CI-PSFCH may be information indicating that collision is predicted in the resource on which the UE-B's PSSCH is transmitted or information indicating that collision is not predicted in the resource (i.e., information transmitted and received via the CI-PSFCH is information indicating whether collision is predicted or not). When only collision prediction information is transmitted and received, only one value in a cyclic shift pair can be used for transmitting and receiving the CI-PSFCH. When transmitting and receiving either information indicating that collision is predicted or information indicating that collision is not predicted depending on the situation, two values ​​in a cyclic shift pair can be assigned to each piece of information. In this case, whether to transmit and receive collision prediction information or information indicating whether collision is predicted or not can be configured via system information or UE-specific RRC signaling.

[0171] As another method, information regarding the priority of data (e.g., PSSCH) transmitted by UE-B and the priority of data (e.g., PSSCH) of another UE (e.g., UE-C) that is predicted to collide with the data transmitted by UE-B may be transmitted and received via the CI-PSFCH. For example, the result of comparing the priority of data transmitted by UE-B with the priority of data of another UE (e.g., UE-C) that is predicted to collide with the data transmitted by UE-B may be transmitted and received via the CI-PSFCH. That is, the CI-PSFCH may indicate that the priority of UE-C's data is lower than the priority of UE-B's data that is predicted to collide with the corresponding resource, or conversely, the CI-PSFCH may indicate that the priority of UE-C's data is higher than the priority of UE-B's data that is predicted to collide with the corresponding resource. In this case, two values ​​of a cyclic shift pair may be assigned to each piece of information and used. If the data priorities of the two UEs are the same, they may be preset to be indicated by one of the two values ​​of the cyclic shift pair. If the priority of UE-C's data is lower than that of UE-B's data, UE-B may not need to perform resource reselection, i.e., UE-B can perform resource reselection only if the priority of UE-C's data is higher than that of UE-B's data.

[0172] Alternatively, information on various collision prediction situations can be transmitted through the CI-PSFCH. For example, two values ​​of a cyclic shift pair can be assigned to a case where collision is predicted due to the reserved resources of other terminals and a case where collision prediction itself cannot be performed. More specifically, a case where collision prediction itself cannot be performed may occur due to a half-duplex issue in which UE-A cannot perform sensing on the control channel of other terminals because it is performing other sidelink transmissions.

[0173] In the manner described above, the two values ​​of the cyclic shift pair may correspond to the 0th and 6th cyclic shifts of the PSFCH sequence, respectively.

[0174] Alternatively, if the transmission time of the CI-PSFCH is determined based on the slot in which the SCI of UE-B used to predict collision is transmitted (i.e., the case of FIG. 14), if the corresponding SCI reserves multiple resources, the presence or absence of predicted collision for each of the multiple reserved resources may be notified via the CI-PSFCH. For example, if the SCI reserves two additional resources (hereinafter referred to as the first reserved resource and the second reserved resource) in addition to the resource for transmitting the PSSCH in the corresponding slot, collision may be predicted for either the first reserved resource or the second reserved resource, or collision may be predicted for both the first and second reserved resources. In this case, UE-A may notify information regarding which reserved resource is predicted to have a collision by applying different cyclic shifts. More specifically, UE-A may transmit the CI-PSFCH using cyclic shift #0 when collision is predicted for the first reserved resource, cyclic shift #1 when collision is predicted for the second reserved resource, and cyclic shift #2 when collision is predicted for both the first and second reserved resources. In the above-described method, cyclic shifts #0, #1, and #2 may correspond to the 0th, 4th, and 8th cyclic shifts of the PSFCH sequence, respectively. Even when resource collision is not predicted, the CI-PSFCH may be transmitted using additional cyclic shift values. If different cyclic shifts are used to indicate whether or not collision is predicted for each reserved resource, the resource coordination information for which of the multiple reserved resources is transmitted via the CI-PSFCH may be preset through system information or PC5-RRC signaling, or may be determined by technical specifications. For example, if only one additional reserved resource can be reserved using the SCI, the information transmitted via the CI-PSFCH may be information for the corresponding reserved resource. If two or more additional reserved resources can be reserved using the SCI, the information transmitted via the CI-PSFCH may be information for the earliest reserved resource (the first reserved resource, if there are first and second reserved resources, as described above).

[0175] <CI-PSFCH Transmission / Reception Priority> When transmitting resource adjustment information, UE-A may dynamically select and transmit the presence / absence information of the aforementioned collision prediction, collision prediction information, and information regarding the priority of collision data according to the situation.

[0176] For example, different M_ID values may be assigned to the presence / absence information of the aforementioned collision prediction (or collision prediction information) and the information regarding the priority of collision data, and UE-A can dynamically select the type of information to be transmitted according to the M_ID value. At this time, the M_ID values corresponding to different types of information may be set in advance through system information or UE-specific RRC signaling. The different M_ID values may also be used to distinguish other types of information in addition to the presence / absence information of the aforementioned collision prediction (or collision prediction information) and the information regarding the priority of collision data. Also, since the resource adjustment information is information regarding resource collisions between multiple terminals (for example, resource collisions between UE-B and UE-C), when the resource adjustment information is transmitted only to some or one of the multiple terminals, whether the resource adjustment information is transmitted to which terminal among the corresponding terminals is set in advance (for example, specified for UE-B), or may be determined considering the data priorities of the corresponding multiple terminals. When multiple CI-PSFCH transmissions are possible, the resource adjustment information may be transmitted to all of the corresponding multiple terminals (for example, UE-B and UE-C).

[0177] If UE-A needs to transmit multiple CI-PSFCHs simultaneously, a CI-PSFCH transmission method is required. When UE-A needs to transmit multiple CI-PSFCHs simultaneously, UE-A can transmit all of the multiple CI-PSFCHs or only some of the multiple CI-PSFCHs. When UE-A transmits only some of the CI-PSFCHs, the number of transmittable CI-PSFCHs can be configured through system information, UE-specific RRC signaling, PC5 RRC signaling, etc. If the number of transmittable CI-PSFCHs is configured in advance, UE-A can transmit the configured number of PSFCH-for-CIs. That is, UE-A can select the configured number of terminal(s) based on the priority of data from multiple terminal(s) for which collisions are predicted, and transmit CI-PSFCHs to the selected terminal(s).

[0178] The priority of the CI-PSFCH may be determined based on the priority of the corresponding data, and the priority of the data may be determined based on the SCI containing scheduling information for the corresponding data. In this case, the highest priority among the priorities of the SCIs containing scheduling information for a pair of PSSCHs for which collision is expected may be selected as the priority of the CI-PSFCH. Alternatively, the priority of the SCI to which actual collision prediction information is transmitted may be selected as the priority of the CI-PSFCH. Alternatively, the priority of the CI-PSFCH may be preset to a specific priority, which may be the highest priority. In addition, if the transmission power required to transmit the preset number of CI-PSFCHs exceeds the maximum transmission power of the terminal, the number of CI-PSFCHs actually transmitted may be additionally limited to a range that does not exceed the terminal transmission power.

[0179] When UE-B receives the CI-PSFCH(s), it must also apply reception priority. Since the CI-PSFCH received by UE-B is information about data scheduled by UE-B, the reception priority of the CI-PSFCH can be determined by applying the priority of the data scheduled by UE-B (i.e., the priority included in the SCI that schedules the corresponding data). In the above procedure, the priority is determined by the priority value, and the highest priority value means the lowest priority.

[0180] When a UE-A transmitting resource coordination information needs to transmit a CI-PSFCH(s) and simultaneously receive a CI-PSFCH(s) from another UE, simultaneous transmission and reception may or may not be possible depending on the UE-A's capability. If simultaneous transmission and reception is not possible, the UE-A can selectively perform transmission or reception operations taking into account the priority of the transmitted CI-PSFCH(s) and the priority of the received CI-PSFCH(s). From the perspective of a single UE, the transmission or reception operation must be determined taking into account both the CI-PSFCH(s) for transmitting and receiving resource coordination information and the AN-PSFCH(s) for transmitting and receiving HARQ ACK / NACK. The operation of the UE in each case will be described below.

[0181] CI-PSFCH(s) transmission & AN-PSFCH(s) transmission: AN-PSFCH(s) may always have higher priority than CI-PSFCH(s). A terminal (e.g., UE-A) may prioritize the transmission of AN-PSFCH(s). Alternatively, without distinguishing between AN-PSFCH(s) and CI-PSFCH(s), a terminal (e.g., UE-A) may compare the priority of the AN-PSFCH(s) to be transmitted with the priority of the CI-PSFCH(s) to be transmitted and transmit the PSFCH with the higher priority. In this case, the maximum number of PSFCHs that can be transmitted may be set in advance by system information or UE-specific RRC signaling, and the number may be further limited by the terminal's transmission power.

[0182] CI-PSFCH(s) transmission & AN-PSFCH(s) reception: For a terminal that cannot transmit and receive simultaneously, reception of AN-PSFCH(s) may always have a higher priority than transmission of CI-PSFCH(s). Therefore, the terminal (e.g., UE-A) can prioritize reception of AN-PSFCH(s). Alternatively, the terminal (e.g., UE-A) can selectively perform transmission or reception according to the higher priority based on the result of comparing the highest priority of the transmitted CI-PSFCH(s) with the highest priority of the received AN-PSFCH(s). In this case, if the highest priorities are the same, comparison can be sequentially performed for the next highest priority.

[0183] CI-PSFCH(s) reception & AN-PSFCH(s) transmission: For a terminal that cannot transmit and receive simultaneously, AN-PSFCH(s) transmission may always have a higher priority than CI-PSFCH(s) reception. Therefore, the terminal (e.g., UE-A) can prioritize the AN-PSFCH(s) transmission operation. Alternatively, based on the result of comparing the highest priority among the received CI-PSFCH(s) with the highest priority among the transmitted AN-PSFCH(s), the terminal (e.g., UE-A) can selectively perform a transmission or reception operation according to the higher priority. In this case, if the highest priorities are the same, the comparison can be sequentially performed for the next highest priority.

[0184] Reception of CI-PSFCH(s) & Reception of AN-PSFCH(s): If the number of PSFCHs that a terminal can simultaneously receive and process is preset according to terminal capability, the terminal (e.g., UE-B) can assume that AN-PSFCH(s) always have a higher priority than CI-PSFCH(s) and can prioritize the reception of AN-PSFCH(s). Alternatively, without distinguishing between AN-PSFCH(s) and CI-PSFCH(s), the terminal (e.g., UE-B) can compare the priorities of the received AN-PSFCH(s) with the priorities of the received CI-PSFCH(s) and prioritize the reception of the PSFCH with the higher priority.

[0185] As described above, whether the AN-PSFCH(s) always have higher priority than the CI-PSFCH(s) or whether the transmission or reception operation for the higher priority is performed preferentially without distinguishing between the CI-PSFCH(s) and the AN-PSFCH(s) can be set through system information, UE-specific RRC signaling, MAC CE, etc.

[0186] If the AN-PSFCH(s) always have a higher priority than the CI-PSFCH(s) in the above procedure, confusion may occur when considering the priority of channels other than the PSFCH(s). For example, a case may be assumed in which the priorities of multiple channels are set in the order of "CI-PSFCH > CH#A (any channel excluding PSFCH) > AN-PSFCH." In this case, if the priority of the AN-PSFCH is compared with the priority of CH#A first, CH#A may be selected. Then, if the priority of CH#A is compared with the priority of the CI-PSFCH, CI-PSFCH may be finally selected. However, if the priorities of the AN-PSFCH and the CI-PSFCH are compared first, AN-PSFCH may always be selected regardless of the actual priority. Then, if the priority of the AN-PSFCH is compared with the priority of CH#A, CH#A may be finally selected. Therefore, the channel finally selected may vary depending on which channel's priority is compared first. Therefore, to prevent such confusion, the priorities of the PSFCHs may be compared preferentially. That is, the priorities of the CI-PSFCH and the AN-PSFCH are compared first, and then the priorities of other channels are compared. Also, when there are multiple CI-PSFCH(s) and multiple AN-PSFCH(s), the priorities of PSFCHs of the same type may be compared first. That is, the priorities of multiple CI-PSFCH(s) are compared, and then the priorities of multiple AN-PSFCH(s) are compared, and then the priorities of the PSFCH selected among them (i.e., the CI-PSFCH and the AN-PSFCH) are compared and then compared with the priorities of other channels.

[0187] Meanwhile, it is necessary to define an operation for the case where transmission and reception of the CI-PSFCH(s) occur simultaneously with LTE sidelink transmission and reception and uplink transmission. As an example, the same method applied when transmission and reception of the AN-PSFCH(s) occur simultaneously with LTE sidelink transmission and reception and uplink transmission can be applied to the case where transmission and reception of the CI-PSFCH(s) occur simultaneously with LTE sidelink transmission and reception and uplink transmission. Furthermore, when transmission and reception of the CI-PSFCH(s) and transmission and reception of the AN-PSFCH(s) occur simultaneously with LTE sidelink transmission and reception and uplink transmission, the priority between the CI-PSFCH(s) and the AN-PSFCH(s) can be considered first, and then the priority between the LTE sidelink transmission and reception and uplink transmission can be considered.

[0188] When there are two or more terminals that cause collisions with specific resources in Scheme 2, UE-A can select a specific terminal among the multiple terminals and transmit collision-related information to UE-B. In this case, the specific terminal that transmits the collision-related information among the terminals causing the collision can be pre-set to UE-B. This can be accomplished in the link setup process between UE-A and the specific terminal (UE-B) through PC5-RRC signaling. As another method, after configuring the multiple terminals causing the collision into pairs of two, a method can be used where the terminal with a lower priority (i.e., a higher priority value) in each pair is set as UE-B and the collision prediction information is transmitted. For example, when it is predicted that terminals UE#1, UE#2, and UE#3 will cause collisions in overlapping resources, pairs #1 {UE#1, UE#2}, pair #2 {UE#1, UE#3}, and pair #3 {UE#2, UE#3} can be formed. If terminals UE#1, UE#2, and UE#3 have priorities in the order of "UE#1 > UE#2 > UE#3" (i.e., the priority value of UE#1 < the priority value of UE#2 < the priority value of UE#3), UE#2 is selected in pair #1, UE#3 is selected in pair #2, UE#3 is selected in pair #3, and UE-A can select UE#2 and UE#3 as UE-B and transmit the collision prediction information. When UE-A needs to transmit the collision prediction information to multiple UE-Bs (UE#2 and UE#3) through CI-PSFCH as described above, if the number of CI-PSFCHs that UE-A can transmit is limited, UE-A can perform an additional UE-B selection process to meet the limited number. More specifically, UE-A can select the terminal with a lower priority among the multiple UE-Bs and transmit CI-PSFCH. In the above example, when transmission is possible only to one of UE#2 and UE#3, UE-A can finally select UE#3 as UE-B and transmit CI-PSFCH to UE#3. When multiple terminals (e.g., UE#2 and UE#3) have the same priority, UE-A can specifically select any terminal. As another method, when multiple terminals (UE#2 and UE#3) have the same priority, UE-A can select UE-B based on the measured RSRP.In this case, the UE with the highest RSRP or the UE with the lowest RSRP may be configured to be selected as UE-B. Alternatively, UE-B may be selected based on various pre-defined criteria, such as the size of data or the size of a resource region where collisions are predicted. If the UE selected based on the above criteria does not support Scheme 2, UE-A may not transmit resource coordination information (i.e., collision prediction information) to the selected UE, or may select a UE with the next lowest priority as UE-B and transmit the resource coordination information (i.e., collision prediction information). In the above example, if UE#3 does not support Scheme 2, UE-A may not transmit the CI-PSFCH or may select UE#2 as UE-B and transmit the CI-PSFCH to UE#2.

[0189] The operations of the methods according to the embodiments of the present invention may be embodied as a computer-readable program or code stored in a computer-readable recording medium. The computer-readable recording medium includes all types of storage devices that store information readable by a computer system. The computer-readable recording medium may also be distributed among computer systems connected to a network, so that the computer-readable program or code may be stored and executed in a distributed manner.

[0190] Additionally, the computer-readable recording medium may include a hardware device specially configured to store and execute program instructions, such as a ROM, RAM, flash memory, etc. The program instructions may include not only machine language code, such as that produced by a compiler, but also high-level language code that can be executed by a computer using an interpreter, etc.

[0191] Although some aspects of the invention have been described in the context of an apparatus, they may also be described in terms of a corresponding method, where a block or apparatus corresponds to a method step or feature of a method step. Similarly, aspects described in the context of a method may also be described in terms of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be performed by (or using) a hardware device, such as, for example, a microprocessor, a programmable computer, or electronic circuitry. In some embodiments, at least one or more of the most significant method steps may be performed by such a device.

[0192] In some embodiments, a programmable logic device (e.g., a field programmable gate array) may be used to perform some or all of the functions of the methods described herein. In some embodiments, a field programmable gate array may operate in conjunction with a microprocessor to perform one of the methods described herein. In general, it is preferred that the methods be performed by some hardware device.

[0193] Although the present invention has been described above with reference to preferred embodiments, it will be understood by those skilled in the art that various modifications and variations of the present invention may be made without departing from the spirit and scope of the present invention as set forth in the following claims.

Claims

1. 1. A method for operating a first terminal performing sidelink communication, comprising: receiving resource adjustment information from a second terminal; If the resource adjustment information is information on one or more preferred resources, selecting candidate resources to be used for transmission of the first terminal based on the one or more preferred resources; and If the resource adjustment information is information on one or more non-preferred resources, excluding the one or more non-preferred resources from candidate resources to be used for transmission of the first terminal. Including, Here, the resource adjustment information is received through a MAC (medium access control) CE (control element), or through a MAC CE and SCI (sidelink control information), The resource adjustment information includes N (N is a natural number equal to or greater than 1) TRIV (Time Resource Indication Value) / FRIV (Frequency Resource Indication Value) combinations, each of the N TRIV / FRIV combinations indicating M (M is a natural number equal to or greater than 1) resources; and The resource coordination information includes a time position and a frequency position of a first resource among the M resources indicated by each of the N TRIV / FRIV combinations. A method of operation of the first terminal.

2. The second terminal is a terminal that receives data transmitted by the first terminal. A method for operating a first terminal according to claim 1.

3. Whether the resource adjustment information is received through MAC CE or MAC CE and SCI is set for each resource pool. A method for operating a first terminal according to claim 1.

4. The frequency location of the first resource is indicated by a starting subchannel index. A method for operating a first terminal according to claim 1.

5. a time position of a first resource among the M resources indicated by a first TRIV / FRIV combination among the N TRIV / FRIV combinations is designated as a reference slot, and time positions of the first resources of the remaining TRIV / FRIV combinations other than the first TRIV / FRIV combination are designated by slot offsets relative to the reference slot; A method for operating a first terminal according to claim 1.

6. The resource adjustment information is received from the second terminal based on an explicit request of the first terminal, or is received from the second terminal in response to satisfaction of a predetermined condition without an explicit request of the first terminal. A method for operating a first terminal according to claim 1.

7. 1. A method for operating a second terminal performing sidelink communication, comprising: generating resource coordination information, which is information regarding one or more preferred resources or one or more non-preferred resources for transmission of the first terminal; and transmitting the resource adjustment information to the first terminal; Including, If the resource adjustment information is information on one or more preferred resources, candidate resources to be used for transmission of the first terminal are selected based on the one or more preferred resources; if the resource adjustment information is information on one or more non-prioritized resources, the one or more non-prioritized resources are excluded from candidate resources to be used for transmission of the first terminal; wherein the resource adjustment information is transmitted through a MAC CE or through a MAC CE and an SCI; The resource coordination information includes N TRIV / FRIV combinations (N is a natural number equal to or greater than 1), and each of the N TRIV / FRIV combinations indicates M resources (M is a natural number equal to or greater than 1); and The resource coordination information includes a time position and a frequency position of a first resource among the M resources indicated by each of the N TRIV / FRIV combinations. A method of operation of the second terminal.

8. Whether the resource adjustment information is transmitted through MAC CE or MAC CE and SCI is determined for each resource pool. A method for operating a second terminal according to claim 7.

9. a time position of a first resource among the M resources indicated by a first TRIV / FRIV combination among the N TRIV / FRIV combinations is indicated as a reference slot, and time positions of the first resources of the remaining TRIV / FRIV combinations other than the first TRIV / FRIV combination are indicated by slot offsets relative to the reference slot; A method for operating a second terminal according to claim 7.

10. A first terminal performing sidelink communication, at least one transceiver; and a processor for controlling the at least one transceiver Including, The processor may further comprise: receiving resource adjustment information from a second terminal using the transceiver; If the resource adjustment information is information on one or more prioritized resources, selecting candidate resources to be used for transmission of the first terminal based on the one or more prioritized resources; and If the resource adjustment information is information on one or more non-prioritized resources, excluding the one or more non-prioritized resources from candidate resources to be used for transmission of the first terminal. configured to carry out wherein the resource adjustment information is received through a MAC CE or through a MAC CE and an SCI; The resource coordination information includes N TRIV / FRIV combinations (N is a natural number equal to or greater than 1), and each of the N TRIV / FRIV combinations indicates M resources (M is a natural number equal to or greater than 1); and The resource coordination information includes a time position and a frequency position of a first resource among the M resources indicated by each of the N TRIV / FRIV combinations. Terminal 1.

11. The second terminal is a terminal that receives data transmitted by the first terminal. The first terminal according to claim 10.

12. Whether the resource adjustment information is received through MAC CE or MAC CE and SCI is determined for each resource pool. The first terminal according to claim 10.

13. The frequency location of the first resource is indicated by a starting subchannel index. The first terminal according to claim 10.

14. a time position of a first resource among the M resources indicated by a first TRIV / FRIV combination among the N TRIV / FRIV combinations is indicated as a reference slot, and time positions of the first resources of the remaining TRIV / FRIV combinations other than the first TRIV / FRIV combination are indicated by slot offsets relative to the reference slot; The first terminal according to claim 10.

15. The resource adjustment information is received from the second terminal based on an explicit request of the first terminal, or is received from the second terminal in response to satisfaction of a predetermined condition without an explicit request of the first terminal. The first terminal according to claim 10.

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