Method and apparatus for transmitting signals in a wireless communication system

Abstract

The present invention relates to a wireless communication system, and more particularly to a method and wireless device therefor, which includes the steps of determining a CAPC value for each SL transmission for multiple SL transmissions within one slot, and performing one Type 1 CAP based on the maximum CAPC value among multiple CAPC values ​​associated with the multiple SL transmissions in order to transmit the multiple SL transmissions in the one slot.

Description

[Technical Field]

[0001] The present invention relates to a new wireless communication system, and more particularly to a channel access method and an apparatus using the same in a wireless communication system. [Background technology]

[0002] Since the commercialization of 4G (4th generation) communication systems, efforts have been made to develop new 5G (5th generation) communication systems to meet the increasing demand for wireless data traffic. 5G communication systems are also called communication systems beyond 4G networks, post-LTE systems, or new radio (NR) systems. To achieve high data transmission rates, 5G communication systems include systems operating using ultra-high frequency (mmWave) bands above 6 GHz. Furthermore, to ensure coverage, communication systems operating using frequency bands below 6 GHz are also being considered for implementation in base stations and terminals.

[0003] The 3GPP (registered trademark, hereinafter the same) (3rd generation partnership project) NR system improves network spectral efficiency, allowing carriers to provide more data and voice services within a given bandwidth. Therefore, the 3GPP NR system is designed to meet the demand for high-speed data and media transmission in addition to high-capacity voice support. The advantages of the NR system include high throughput, low latency, support for frequency division duplex (FDD) and time division duplex (TDD) on the same platform, an improved end-user experience, and low operating costs due to a simple architecture.

[0004] For more efficient data processing, dynamic TDD in the NR system can use a scheme of varying the number of orthogonal frequency division multiplexing (OFDM) symbols available for uplink and downlink use according to the data traffic direction of users in the cell. For example, if the downlink traffic of a cell is greater than the uplink traffic, the base station can allocate a relatively large number of downlink OFDM symbols to a slot (or subframe). Information about the slot configuration needs to be transmitted to the terminal.

[0005] To mitigate the path loss of radio waves in the ultra-high frequency band and increase the transmission distance of radio waves, technologies being discussed for 5G communication systems include beamforming, massive MIMO, full dimensional MIMO (FD-MIMO), array antenna, analog beamforming, hybrid beamforming that combines analog beamforming and digital beamforming, and large scale antenna technology. In addition, to improve the system's network, technological developments are being made in the 5G communication system regarding advanced small cells, improved small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device to device communication (D2D), vehicle to everything communication (V2X), wireless backhaul, non-terrestrial network communication (NTN), moving networks, cooperative communication, coordinated multi-points (CoMP), and interference cancellation.Other advanced coding modulation (ACM) methods being developed for 5G systems include hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC), as well as advanced access technologies such as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA).

[0006] Meanwhile, the Internet, a human-centered network where humans generate and consume information, is evolving into the IoT (Internet of Things) network, which exchanges and processes information among distributed components such as objects. IoE (Internet of Everything) technology, which combines big data processing technology through connections with cloud servers, is also emerging. To realize the IoT, technological elements such as sensing technology, wired and wireless communication and network infrastructure, service interface technology, and security technology are required. Recently, research has focused on sensor networks, machine-to-machine (M2M), and machine-type communication (MTC) technologies for connecting objects. In an IoT environment, intelligent IT (internet technology) services are provided that collect and analyze data generated by connected objects and create new value in human life. Through the integration and convergence of traditional IT technology and various industries, the IoT is being applied to areas such as smart homes, smart buildings, smart cities, smart or connected cars, smart grids, healthcare, smart home appliances, and advanced medical services.

[0007] Therefore, various attempts are being made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine-to-machine, and MTC are being implemented using 5G communication technologies such as beamforming, MIMO, and array antennas. The application of cloud radio access networks (cloud RAN), the big data processing technology mentioned above, is also an example of the fusion of 5G and IoT technologies. In general, mobile communication systems are being developed to provide voice services while ensuring user activity.

[0008] Sidelink (SL) is a communication method that establishes a direct link between terminals (User Equipment, UE) to directly transmit and receive voice or data between terminals without going through a base station (BS). SL is being considered as a solution to alleviate the burden on base stations due to the rapidly increasing data traffic.

[0009] V2X (vehicle-to-everything) refers to a communication technology that exchanges information with other vehicles, pedestrians, infrastructure, etc. using wired or wireless communications. V2X can be divided into four types: V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), and V2P (vehicle-to-pedestrian). V2X communication may be provided via a PC5 interface and / or a Uu interface.

[0010] Meanwhile, as more communication devices require larger communication capacities, there is an increasing need for improved mobile broadband communication compared to existing radio access technologies (RATs). To this end, communication systems that take into account reliability- and latency-sensitive services or terminals are being discussed. Next-generation wireless access technologies that take into account improved mobile broadband communication, massive MTC, and ultra-reliable and low latency communication (URLLC) can be called new radio access technologies (RATs) or new radios (NRs). NRs may also support vehicle-to-everything (V2X) communication.

[0011] Meanwhile, for example, in SL communications associated with services having high or relatively high reliability requirements, SL HARQ feedback operations and / or mechanisms of the terminal may be useful. Summary of the Invention [Problem to be solved by the invention]

[0012] An object of the present invention is to provide a method for efficiently transmitting signals in a wireless communication system and an apparatus using the same. Specifically, an object of the present invention is to provide a channel access method for efficiently transmitting signals in a wireless communication system and an apparatus using the same. [Means for solving the problem]

[0013] In one aspect of the present invention, there is provided a terminal for use in a wireless communication system, comprising: a communication module; and a processor for controlling the communication module, wherein the processor is configured to determine a CAPC (channel access priority class) value for each of a plurality of SL (sidelink) transmissions within one slot; and to perform one Type 1 CAP (channel access procedure) based on the largest CAPC value among a plurality of CAPC values ​​associated with the plurality of SL transmissions in order to transmit the plurality of SL transmissions in the one slot.

[0014] In another aspect of the present invention, there is provided a method used by a terminal in a wireless communication system, comprising: determining a CAPC (channel access priority class) value for each of a plurality of SL (sidelink) transmissions in one slot; and performing one Type 1 CAP (channel access procedure) based on the maximum CAPC value among a plurality of CAPC values ​​associated with the plurality of SL transmissions in order to transmit the plurality of SL transmissions in the one slot.

[0015] Preferably, the plurality of CAPC values ​​are associated with respective CW (contention window) parameters, and the larger the CAPC value, the lower the channel access priority of the CW parameter.

[0016] Preferably, if the one Type 1 CAP is successful, the multiple SL transmissions may be sent to the corresponding receiving terminals.

[0017] Preferably, the multiple SL transmissions may correspond to two or more receiving terminals.

[0018] Preferably, the multiple SL transmissions may be scheduled for transmission on the same time resource within the one slot.

[0019] Preferably, the multiple SL transmissions may be scheduled for transmission on different frequency resources within the one slot.

[0020] Preferably, the plurality of SL transmissions may include a physical sidelink feedback channel (PSFCH) transmission.

[0021] Preferably, the plurality of SL transmissions may include a plurality of PSFCH transmissions.

[0022] Preferably, the CAPC value associated with the PSFCH transmission may be determined based on the traffic priority of a physical sidelink shared channel (PSSCH) corresponding to the PSFCH transmission.

[0023] Preferably, the traffic priority may be determined based on priority information in sidelink control information (SCI) that schedules the PSSCH. [Effects of the Invention]

[0024] The present invention provides a method for efficiently transmitting signals in a wireless communication system and an apparatus using the same. The present invention also provides a channel access method for efficiently transmitting signals in a wireless communication system and an apparatus using the same.

[0025] The effects obtained from the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those having ordinary skill in the art to which the present invention pertains from the following description. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a diagram illustrating an example of a radio frame structure used in a wireless communication system. [Figure 2]1 is a diagram illustrating an example of a downlink (DL) / uplink (UL) slot structure in a wireless communication system. [Figure 3] FIG. 1 is a diagram illustrating physical channels used in a 3GPP system (e.g., NR) and a general signal transmission method using the physical channels. [Figure 4] 2A and 2B are block diagrams showing the configurations of a terminal and a base station according to an embodiment of the present invention. [Figure 5] FIG. 1 is a diagram illustrating a sidelink (SL) communication process. [Figure 6] FIG. 1 is a diagram illustrating a sidelink (SL) communication process. [Figure 7] FIG. 1 is a diagram illustrating a sidelink (SL) communication process. [Figure 8] FIG. 1 is a diagram illustrating a sidelink (SL) communication process. [Figure 9] FIG. 1 is a diagram illustrating a sidelink (SL) communication process. [Figure 10] FIG. 1 is a diagram illustrating a sidelink (SL) communication process. [Figure 11] FIG. 1 is a diagram illustrating a sidelink (SL) communication process. [Figure 12] FIG. 1 is a diagram illustrating a sidelink (SL) communication process. [Figure 13] FIG. 10 is a diagram illustrating an example of the structure within a slot of PSCCH / PSSCH / PSFCH (physical sidelink control channel / physical sidelink shared channel / physical sidelink feedback channel). [Figure 14] FIG. 1 is a diagram illustrating the structure of S-SSB (sidelink SSB). [Figure 15] FIG. 10 illustrates an example of a method for a sidelink terminal to determine a PSFCH resource. [Figure 16] FIG. 1 is a diagram illustrating an NR-U (NR-Unlicensed) service environment. [Figure 17]1 is a diagram illustrating an existing communication system (e.g., wireless LAN) that operates in an unlicensed band. [Figure 18] A diagram showing the channel access process based on Category 4 LBT. [Figure 19] 10A and 10B are diagrams illustrating an example of COT (channel occupancy time) setting and operations based thereon. [Figure 20] FIG. 10 is a diagram illustrating multiple SL transmissions. [Figure 21] 1 is a diagram illustrating an SL transmission method according to the present invention. [Figure 22] 1 is a diagram illustrating an SL transmission method according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] The terms used in this specification are generally used as widely as possible, taking into consideration the functions of the present invention. However, these may vary depending on the intentions of those skilled in the art, practice, or the emergence of new technologies. In addition, in certain cases, the applicant may arbitrarily select terms. In such cases, the meaning of the terms will be described in the description of the relevant invention. Therefore, it is clear that the terms used in this specification should be interpreted based on the substantive meaning of the terms and the overall content of this specification, rather than simply the names of the terms.

[0028] Throughout this specification, when a component is said to be "connected" to another component, this includes not only "directly connected" but also "electrically connected" through other components in between. Furthermore, when a component is said to "comprise" a specific component, this does not mean excluding the other component, but also means including the other component, unless otherwise specified to the contrary. In addition, limitations such as "more than" or "less than" based on a specific threshold may be appropriately replaced with "more than" or "less than," respectively, depending on the embodiment.

[0029] The following technologies are used in various wireless access systems, such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), and SC-FDMA (single carrier frequency division multiple access). CDMA is implemented in radio technologies such as UTRA (Universal Terrestrial Radio Access) and CDMA2000. TDMA is implemented in radio technologies such as GSM (Global System for Mobile communications), GPRS (General Packet Radio Service), and EDGE (Enhanced Data Rates for GSM Evolution). OFDMA is implemented in radio technologies such as IEEE802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE802-20, and E-UTRA (Evolved UTRA). UTRA is part of UMTS (Universal Mobile Telecommunications System). 3GPP LTE (Long term evolution) is a part of E-UMTS (Evolved UMTS) that uses E-UTRA, and LTE-A (Advanced) is an evolved version of 3GPP LTE. 3GPP NR is a system designed separately from LTE / LTE-A and is a system for supporting eMBB (enhanced Mobile Broadband), URLLC (Ultra-Reliable and Low Latency Communication), and mMTC (massive Machine Type Communication) services, which are requirements of IMT-2020. For clarity of explanation, the following description will focus on 3GPP NR, but the technical concept of the present invention is not limited thereto.

[0030] Unless otherwise specified herein, the base station may include a next generation node B (gNB) defined in 3GPP NR. Also, unless otherwise specified, the terminal may include a user equipment (UE). Hereinafter, to facilitate understanding of the description, each content will be described as a separate embodiment, but each embodiment may be used in combination with each other. In this disclosure, "configuring" a terminal may mean configuration by a base station. Specifically, the base station may transmit a channel or a signal to the terminal to configure the operation of the terminal or parameter values ​​used in the wireless communication system.

[0031] FIG. 1 is a diagram illustrating an example of a radio frame structure used in a radio communication system.

[0032] Referring to FIG. 1, a radio frame used in a 3GPP NR system has a length of 10 ms (ΔfmaxNf / 100)*Tc). Each radio frame consists of 10 equally sized subframes (SF). Here, Δfmax=480*103 Hz, Nf=4096, Tc=1 / (Δfref*Nf,ref), Δfref=15*103 Hz, and Nf,ref=2048. The 10 subframes in a frame are numbered 0 to 9. Each subframe has a length of 1 ms and consists of one or more slots depending on the subcarrier spacing. More specifically, the subcarrier spacing that can be used in a 3GPP NR system is 15*2 μkHz. μ is the subcarrier spacing configuration factor and has values ​​from 0 to 4. That is, 15 kHz, 30 kHz, 60 kHz, 120 kHz, or 240 kHz is used as the subcarrier spacing. A 1 ms long subframe consists of 2μ slots, each of which is 2-μms long. The 2μ slots in one subframe are numbered from 0 to 2μ-1. The slots in one radio frame are numbered from 0 to 10*2μ-1. Time resources are divided by at least one of the radio frame number (also called radio frame index), subframe number (also called subframe index), and slot number (or slot index).

[0033] 2 is a diagram illustrating an example of a downlink (DL) / uplink (UL) slot structure in a wireless communication system, particularly illustrating a resource grid structure in a 3GPP NR system.

[0034] There is one resource grid per antenna port. Referring to FIG. 2, a slot includes multiple OFDM symbols in the time domain and multiple resource blocks (RBs) in the frequency domain. An OFDM symbol also refers to one symbol interval. Unless otherwise specified, an OFDM symbol is simply referred to as a symbol. Hereinafter, the term "symbol" includes OFDM symbols, SC-FDMA symbols, DFTs-OFDM symbols, etc. Referring to FIG. 2, a signal transmitted from each slot is represented by a resource grid consisting of Nsize, μgrid, x*NRBSC subcarriers, and Nslotsymb OFDM symbols. Here, x=DL for the downlink resource grid and x=UL for the uplink resource grid. Nsize, μgrid, and x denote the number of resource blocks (RBs) according to the subcarrier spacing factor μ (x is DL or UL), and Nslotsymb denotes the number of OFDM symbols in a slot. NRBSC is the number of subcarriers constituting one RB, and NRBSC=12. Depending on the multiple access method, the OFDM symbol is called a cyclic prefix OFDM (CP-OFDM) symbol or a discrete Fourier transform spread OFDM (DFT-S-OFDM) symbol.

[0035] The number of OFDM symbols included in one slot may vary depending on the length of the cyclic prefix (CP). For example, a normal CP includes 14 OFDM symbols, while an extended CP includes 12 OFDM symbols. In a specific embodiment, the extended CP is used only with a subcarrier spacing of 60 kHz. For convenience of explanation, FIG. 2 illustrates a case where one slot consists of 14 OFDM symbols. However, the present invention is equally applicable to slots having other numbers of OFDM symbols. Referring to FIG. 2, each OFDM symbol includes Nsize, μgrid, and x*NRBSC subcarriers in the frequency domain. Subcarriers are classified into data subcarriers for transmitting data, reference signal subcarriers for transmitting reference signals, and guard bands. The carrier frequency is also called the center frequency (fc).

[0036] One RB is defined by NRBSC (e.g., 12) consecutive subcarriers in the frequency domain. Incidentally, a resource consisting of one OFDM symbol and one subcarrier is called a resource element (RE) or tone. Therefore, one RB consists of Nslotsymb*NRBSC resource elements. Each resource element in the resource grid is uniquely defined by an index pair (k, l) within one slot. k is an index ranging from 0 to Nsize, μgrid, x*NRBSC-1 in the frequency domain, and l is an index ranging from 0 to Nslotsymb-1 in the time domain.

[0037] In order for a terminal to receive a signal from a base station or transmit a base station signal, the time / frequency synchronization of the terminal must be aligned with the time / frequency synchronization of the base station, because if the base station and the terminal are not synchronized, the terminal cannot determine the time and frequency parameters required to demodulate DL signals and transmit UL signals at the correct time.

[0038] Each symbol in a radio frame operating in time division duplex (TDD) or unpaired spectrum consists of at least one of a downlink symbol (DL symbol), an uplink symbol (UL symbol), or a flexible symbol. A radio frame operating on a downlink carrier in frequency division duplex (FDD) or paired spectrum consists of downlink symbols or flexible symbols, and a radio frame operating on an uplink carrier consists of uplink symbols or flexible symbols. A downlink symbol allows downlink transmission but not uplink transmission, and an uplink symbol allows uplink transmission but not downlink transmission. Whether a flexible symbol is used for downlink or uplink is determined depending on the signal.

[0039] Information about the type of each symbol, i.e., information indicating any one of downlink symbols, uplink symbols, and flexible symbols, is formed by a cell-specific (or common) RRC signal. The information about each symbol type is additionally formed by a UE-specific (or dedicated) RRC signal. The base station uses the cell-specific RRC signal to notify i) the period of the cell-specific slot configuration, ii) the number of slots having only downlink symbols from the beginning of the period of the cell-specific slot configuration, iii) the number of downlink symbols from the first symbol in the slot immediately following the slot having only downlink symbols, iv) the number of slots having only uplink symbols from the end of the period of the cell-specific slot configuration, and v) the number of uplink symbols from the last symbol in the slot immediately preceding the slot having only uplink symbols. Here, symbols that are not configured as either uplink or downlink symbols are flexible symbols.

[0040] If the information regarding the symbol type consists of the per-terminal RRC signal, the base station signals, by means of the cell-specific RRC signal, whether the flexible symbol is a downlink symbol or an uplink symbol. At this time, the per-terminal RRC signal cannot change a downlink symbol or an uplink symbol, which consists of the cell-specific RRC signal, to another symbol type. The per-terminal RRC signal signals, for each slot, the number of downlink symbols among the Nslotsymb symbols of the slot and the number of uplink symbols among the Nslotsymb symbols of the slot. At this time, the downlink symbols of the slot are continuously configured from the first symbol to the i-th symbol of the slot. Also, the uplink symbols of the slot are continuously configured from the j-th symbol to the last symbol of the slot (where i < j). In a slot, a symbol that is not configured as either an uplink symbol or a downlink symbol is a flexible symbol.

[0041] The type of symbol configured by the RRC signal as described above can be called a semi-static DL / UL configuration. In the semi-static DL / UL configuration configured by the RRC signal previously, the flexible symbol may be indicated as a downlink symbol, an uplink symbol, or a flexible symbol by the dynamic SFI (slot format information) transmitted on the physical downlink control channel (PDCCH). At this time, a downlink symbol or an uplink symbol configured by the RRC signal is not changed to another symbol type.

[0042] FIG. 3 is a diagram for explaining a physical channel used in a 3GPP system (for example, NR) and a general signal transmission method using the physical channel.

[0043] When a terminal is powered on or newly enters a cell, the terminal performs an initial cell search (S101). Specifically, the terminal synchronizes with a base station during the initial cell search. To do this, the terminal receives a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) from the base station to synchronize with the base station and acquire information such as a cell index. Next, the terminal receives a physical broadcast channel from the base station to acquire broadcast information within the cell.

[0044] After completing the initial cell search, the terminal receives a physical downlink shared channel (PDSCH) via a physical downlink control channel (PDCCH) and information carried on the PDCCH to acquire more detailed system information than that acquired through the initial cell search (S102). Here, the system information transmitted to the terminal is cell-common system information for the terminal to operate correctly in a physical layer in Radio Resource Control (RRC), and is called remaining system information or system information block (SIB) 1.

[0045] When a terminal first connects to a base station or when there are no radio resources for signal transmission (when the terminal is in RRC_IDLE mode), the terminal can perform a random access procedure with the base station (steps S103 to S106). First, the terminal transmits a preamble on a physical random access channel (PRACH) (S103) and can receive a response message for the preamble from the base station on a PDCCH and a corresponding PDSCH (S104). If the terminal receives a valid random access response message, the terminal transmits data including its own identifier, etc. to the base station on a physical uplink shared channel (PUSCH) indicated by an uplink grant transmitted from the base station on the PDCCH (S105). Next, the terminal waits for reception of a PDCCH as instructed by the base station to resolve collisions. If the terminal successfully receives the PDCCH with its own identifier (S106), the random access procedure ends. During the random access procedure, the terminal can acquire terminal-specific system information required for the terminal to operate correctly in the physical layer of the RRC layer. If the terminal acquires the terminal-specific system information in the RRC layer, the terminal enters the RRC connected mode (RRC_CONNECTED mode).

[0046] The RRC layer is used to generate and manage messages for control between a terminal and a radio access network (RAN). Furthermore, the base station and terminal can broadcast cell system information required for all terminals in the cell, manage paging message transmission, manage mobility and handover, report terminal measurements and related control, and manage and store terminal capabilities at the RRC layer. Generally, the update of signals transmitted at the RRC layer (hereinafter referred to as RRC signals) is longer than the transmission / reception period (i.e., transmission time interval, TTI) at the physical layer, so that the RRC configuration can be maintained unchanged for a long period.

[0047] After the above procedures, the UE receives a PDCCH / PDSCH (S107) and transmits a physical uplink shared channel (PUSCH) / physical uplink control channel (PUCCH) (S108) as a general uplink / downlink signal transmission procedure. In particular, the UE receives downlink control information (DCI) via the PDCCH. The DCI includes control information such as resource allocation information for the UE. The format of the DCI may vary depending on the purpose of use. The uplink control information (UCI) transmitted by the UE to the base station via the uplink includes a downlink / uplink ACK / NACK signal, a channel quality indicator (CQI), a precoding matrix index (PMI), a rank indicator (RI), etc. Here, the CQI, PMI, and RI are included in channel state information (CSI). In the case of a 3GPP NR system, the UE transmits control information such as the above-mentioned HARQ-ACK and CSI via the PUSCH and / or PUCCH.

[0048] 4 is a block diagram illustrating the configuration of a terminal and a base station according to an embodiment of the present invention. In an embodiment of the present invention, the terminal may be implemented as any of various types of wireless communication devices or computing devices that ensure portability and mobility. The terminal may be referred to as a UE, a station (STA), a mobile subscriber (MS), etc. In addition, in an embodiment of the present invention, the base station controls and manages cells (e.g., macrocells, femtocells, picocells, etc.) corresponding to a service area, and performs functions such as signal transmission, channel assignment, channel monitoring, self-diagnosis, and relaying. The base station may be referred to as a next generation NodeB (gNB) or an access point (AP), etc.

[0049] As shown, a terminal 100 according to one embodiment of the present invention includes a processor 110 , a communication module 120 , a memory 130 , a user interface unit 140 , and a display unit 150 .

[0050] First, the processor 110 executes various commands or programs to process data within the terminal 100. The processor 110 also controls the overall operation of the terminal 100, including each unit, and controls the transmission and reception of data between the units. Here, the processor 110 is configured to perform operations according to the embodiments described in the present invention. For example, the processor 110 may receive slot configuration information, determine the slot configuration based on the information, and perform communication according to the determined slot configuration.

[0051] Next, the communication module 120 is an integrated module that performs wireless communication using a wireless communication network and wireless LAN access using a wireless LAN. To this end, the communication module 120 includes multiple network interface cards (NICs) such as cellular communication interface cards 121 and 122 and an unlicensed band communication interface card 123, either built-in or external. Although the communication module 120 is shown as an integrated module in the drawings, the network interface cards may be independently arranged depending on the circuit configuration or application, unlike the drawings.

[0052] The cellular communication interface card 121 transmits and receives wireless signals to and from at least one of the base station 200, an external device, and a server via a mobile communication network, and provides cellular communication services in a first frequency band based on instructions from the processor 110. According to one embodiment, the cellular communication interface card 121 includes at least one NIC module that utilizes a frequency band below 6 GHz. The at least one NIC module of the cellular communication interface card 121 independently performs cellular communication with at least one of the base station 200, the external device, and the server in accordance with a cellular communication standard or protocol for the frequency band below 6 GHz supported by the NIC module.

[0053] The cellular communication interface card 122 transmits and receives wireless signals to and from at least one of the base station 200, an external device, and a server using a mobile communication network, and provides cellular communication services in the second frequency band based on instructions from the processor 110. According to one embodiment, the cellular communication interface card 122 includes at least one NIC module that uses a frequency band above 6 GHz. The at least one NIC module of the cellular communication interface card 122 independently performs cellular communication with at least one of the base station 200, the external device, and the server in accordance with the cellular communication standard or protocol for the frequency band above 6 GHz that the NIC module supports.

[0054] The unlicensed band communication interface card 123 transmits and receives wireless signals to and from at least one of the base station 200, an external device, and a server via the third frequency band, which is an unlicensed band, and provides unlicensed band communication services based on instructions from the processor 110. The unlicensed band communication interface card 123 includes at least one NIC module that utilizes the unlicensed band. For example, the unlicensed band may be 2.4 GHz, 5 GHz, 6 GHz, 7 GHz, or 52.6 GHz or higher. The at least one NIC module of the unlicensed band communication interface card 123 independently or dependently performs cellular communication with at least one of the base station 200, the external device, and the server according to the unlicensed band communication standard or protocol of the frequency band supported by the NIC module.

[0055] The memory 130 stores control programs and various data used by the terminal 100. The control programs include predetermined programs required for the terminal 100 to perform wireless communication with at least one of the base station 200, an external device, and a server.

[0056] Next, the user interface 140 includes various types of input / output means provided in the terminal 100. That is, the user interface unit 140 receives user input using various input means, and the processor 110 controls the terminal 100 based on the received user input. Also, the user interface 140 performs output based on instructions from the processor 110 using various output means.

[0057] The display unit 150 then outputs various images to a display screen, and displays various display objects such as a user interface based on the content or control instructions of the processor 110.

[0058] The base station 200 according to the embodiment of the present invention also includes a processor 210 , a communication module 220 , and a memory 230 .

[0059] First, the processor 210 executes various instructions or programs to process data within the base station 200. The processor 210 also controls the overall operation of the base station 200, including each unit, and controls the transmission and reception of data between the units. Here, the processor 210 is configured to perform operations according to the embodiments described herein. For example, the processor 210 may signal slot configuration information and perform communication according to the signaled slot configuration.

[0060] Next, the communication module 220 is an integrated module that performs wireless communication using a wireless communication network and wireless LAN access using a wireless LAN. To this end, the communication module 220 includes multiple network interface cards, such as cellular communication interface cards 221 and 222 and an unlicensed band communication interface card 223, either built-in or externally mounted. Although the communication module 220 is shown as an integrated module in the drawings, the network interface cards may be independently arranged depending on the circuit configuration or application, unlike the drawings.

[0061] The cellular communication interface card 221 transmits and receives wireless signals to and from at least one of the terminal 100, the external device, and the server using a mobile communication network, and provides cellular communication services in the first frequency band based on instructions from the processor 210. According to one embodiment, the cellular communication interface card 221 includes at least one NIC module that uses a frequency band below 6 GHz. The at least one NIC module of the cellular communication interface card 221 independently performs cellular communication with at least one of the terminal 100, the external device, and the server according to a cellular communication standard or protocol for the frequency band below 6 GHz supported by the NIC module.

[0062] The cellular communication interface card 222 transmits and receives wireless signals to and from at least one of the terminal 100, an external device, and a server using a mobile communication network, and provides cellular communication services in the second frequency band based on instructions from the processor 210. According to one embodiment, the cellular communication interface card 222 includes at least one NIC module that uses a frequency band above 6 GHz. The at least one NIC module of the cellular communication interface card 222 independently performs cellular communication with at least one of the terminal 100, the external device, and the server according to a cellular communication standard or protocol for the 6 GHz or higher frequency band supported by the NIC module.

[0063] The unlicensed band communication interface card 223 transmits and receives wireless signals to and from at least one of the terminal 100, an external device, and a server using the third frequency band, which is an unlicensed band, and provides unlicensed band communication services based on instructions from the processor 210. The unlicensed band communication interface card 223 includes at least one NIC module that uses the unlicensed band. For example, the unlicensed band may be 2.4 GHz, 5 GHz, 6 GHz, 7 GHz, or 52.6 GHz or higher. The at least one NIC module of the unlicensed band communication interface card 223 independently or dependently performs cellular communication with at least one of the terminal 100, an external device, and a server according to the unlicensed band communication standard or protocol of the frequency band supported by the NIC module.

[0064] The terminal 100 and the base station 200 shown in FIG. 4 are block diagrams according to an embodiment of the present invention, and the blocks shown separately logically distinguish the elements of the device. Therefore, the above-described elements of the device can be attached to one chip or a plurality of chips according to the design of the device. Also, some configurations of the terminal 100, for example, the user interface unit 150 and the display unit 150, etc., may be selectively provided in the terminal 100. Further, the user interface 140 and the display unit 150, etc., may be additionally provided in the base station 200 as necessary.

[0065] <SL (sidelink) communication>

[0066] SL communication refers to a communication method in which a direct link is set between terminals and voice or data, etc., is directly exchanged between terminals without going through a base station. In SL communication, in FIG. 14, the base station may be replaced by a terminal. SL communication may be used in the same sense as V2X (Vehicle-to-everything) communication.

[0067] FIG. 5 shows an example of a terminal and a base station for performing V2X or SL communication.

[0068] Referring to FIG. 5, in V2X / SL communication, the term "terminal" can mainly mean a user's terminal. However, when network equipment such as a base station transmits and receives signals according to the communication method between terminals, the base station may also be regarded as a kind of terminal.

[0069] The terminal 1 can operate to select a resource unit corresponding to a specific resource within a resource pool that means a set of a series of resources, and transmit an SL signal using the resource unit. The receiving terminal, terminal 2, is set with a resource pool in which the terminal 1 can transmit a signal, and can detect the signal of the terminal 1 within the resource pool.

[0070] Here, when the terminal 1 is within the coverage area of ​​the base station, the base station may inform the terminal of the resource pool, whereas when the terminal 1 is outside the coverage area of ​​the base station, another terminal may inform the terminal of the resource pool, or the resource pool may be determined as a predetermined resource.

[0071] FIG. 6 is a diagram illustrating an example of a resource unit for V2X or SL communication.

[0072] Referring to Figure 6, the resource pool may be configured with a plurality of resource units, and each terminal may select one or more resource units to use for its SL signal transmission. F The total time resources in the resource pool can be divided into N T Therefore, the total number of N F *N T Resource units may be defined within a resource pool.

[0073] As shown in Figure 6, one resource unit (e.g., Unit #0) may appear repeatedly periodically. Alternatively, to obtain a diversity effect in the time or frequency dimension, the index of the physical resource unit to which one logical resource unit is mapped may change over time in a predetermined pattern. In such a resource unit structure, a resource pool may refer to a set of resource units available for transmission by a terminal that wishes to transmit an SL signal.

[0074] The resource pools may be subdivided into various types. For example, the resource pools may be classified as follows according to the content of the SL signals transmitted in each resource pool:

[0075] (1) A Scheduling Assignment (SA) may be a signal including information such as the location of resources used by a transmitting terminal for transmitting an SL data channel, a Modulation and Coding Scheme (MCS) or a Multiple Input Multiple Output (MIMO) transmission method, and a Timing Advance (TA) required for demodulating other data channels. The SA may be multiplexed and transmitted together with SL data on the same resource unit, and in this case, the SA resource pool may refer to a resource pool in which the SA is multiplexed and transmitted together with the SL data. The SA may also be referred to as an SL control channel.

[0076] (2) The SL data channel (Physical Sidelink Shared Channel, PSSCH) may be a resource pool used by a transmitting terminal to transmit user data. If SA is multiplexed and transmitted together with SL data on the same resource unit, only the SL data channel excluding SA information may be transmitted in the resource pool for the SL data channel. In other words, REs (Resource Elements) used to transmit SA information on individual resource units in the SA resource pool may still be used to transmit SL data in the resource pool for the SL data channel.

[0077] Below, resource allocation is explained in SL.

[0078] FIG. 7 shows an example of a procedure for a terminal to perform V2X or SL communication in transmission mode.

[0079] Referring to FIG. 7, (a) of FIG. 7 illustrates terminal operation associated with transmission mode 1 or transmission mode 3, and (b) of FIG. 7 illustrates terminal operation associated with transmission mode 2 or transmission mode 4.

[0080] Referring to (a) of FIG. 7, in transmission modes 1 / 3, a base station performs resource scheduling for terminal 1 using a PDCCH (more specifically, Downlink Control Information (DCI)), and terminal 1 performs SL / V2X communication with terminal 2 through the resource scheduling. Terminal 1 transmits sidelink control information (SCI) to terminal 2 through a physical sidelink control channel (PSCCH), and then transmits data based on the SCI through a physical sidelink shared channel (PSSCH). In the case of LTE SL, transmission mode 1 may be applied to general SL communication, and transmission mode 3 may be applied to V2X SL communication.

[0081] Referring to (b) of FIG. 7, in transmission mode 2 / 4, a terminal can independently schedule resources. More specifically, in the case of LTE SL, transmission mode 2 is applied to general SL communication, in which a terminal can independently select resources within a configured resource pool to perform SL operation. Transmission mode 4 is applied to V2X SL communication, in which a terminal can independently select resources within a selection window through a sensing / SA decoding process, etc., and then perform V2X SL operation. Terminal 1 can transmit an SCI to terminal 2 via a PSCCH and then transmit data based on the SCI via a PSSCH. Hereinafter, the transmission mode may be abbreviated as "mode." Procedures related to sensing and resource (re)selection may be supported in resource allocation mode 2. The sensing procedure may be defined as decoding an SCI from other terminals and / or SL measurements. Decoding the SCI in the sensing procedure may provide at least information regarding the SL resource indicated by the terminal transmitting the SCI. When the SCI is decoded, the sensing procedure can use L1 SL Reference Signal Received Power (RSRP) measurements based on SL Demodulation Reference Signal (DMRS), and the resource (re)selection procedure can use the results of the sensing procedure to determine the resources for SL transmission.

[0082] FIG. 8 shows an example of a method for a terminal to select a transmission resource for transmitting a signal.

[0083] Referring to FIG. 8, a terminal can grasp transmission resources reserved by other terminals or resources used by other terminals by sensing within the sensing window, and after eliminating these within the selection window, can randomly select a resource from the remaining resources with the least interference.

[0084] For example, the terminal may decode a PSCCH containing information about the periodicity of reserved resources within a sensing window and measure the PSSCH RSRP at resources periodically determined based on the PSCCH. The terminal may exclude resources whose PSSCH RSRP values ​​exceed a threshold from the selection window. The terminal may then randomly select an SL resource from the remaining resources in the selection window.

[0085] Figure 9 shows an example of three cast types for the NR sidelink.

[0086] Referring to FIG. 9, the NR sidelink supports three types of SL communication: unicast, groupcast, and broadcast. In unicast-type SL communication, a terminal can perform one-to-one communication with other terminals. In groupcast-type SL communication, a terminal can perform SL communication with one or more terminals in a group to which the terminal belongs. Groupcast-type SL communication may be replaced by SL multicast communication, SL one-to-many communication, etc.

[0087] The following describes the HARQ (Hybrid Automatic Repeat Request) procedure in SL.

[0088] In SL unicast and groupcast, HARQ feedback and HARQ combining in the physical layer may be supported. For example, when a receiving terminal operates in resource allocation mode 1 or 2, the receiving terminal can receive a PSSCH from a transmitting terminal, and the receiving terminal can transmit HARQ feedback for the PSSCH to the transmitting terminal using a sidelink feedback control information (SFCI) format in a physical sidelink feedback channel (PSFCH).

[0089] For example, SL HARQ feedback may be enabled for groupcast, i.e., in non-CBG operation, two HARQ feedback options may be supported for groupcast.

[0090] (1) Groupcast Option 1: After a receiving terminal decodes a PSCCH targeted at the receiving terminal, if the receiving terminal fails to decode a transmission block associated with the PSCCH, the receiving terminal can transmit a HARQ-NACK to the transmitting terminal on a PSFCH. On the other hand, if the receiving terminal decodes a PSCCH targeted at the receiving terminal and successfully decodes a transmission block associated with the PSCCH, the receiving terminal does not need to transmit a HARQ-ACK to the transmitting terminal.

[0091] (2) Groupcast option 2: After a receiving terminal decodes a PSCCH targeted at the receiving terminal, if the receiving terminal fails to decode a transmission block associated with the PSCCH, the receiving terminal can transmit a HARQ-NACK to the transmitting terminal on a PSFCH. Then, after the receiving terminal decodes a PSCCH targeted at the receiving terminal and successfully decodes a transmission block associated with the PSCCH, the receiving terminal can transmit a HARQ-ACK to the transmitting terminal on a PSFCH.

[0092] Meanwhile, for example, in SL communication related to a service having a high reliability requirement or a service having a relatively high reliability requirement, an SL HARQ feedback operation and / or mechanism of the UE may be useful. For example, in SL communication related to a service having a high reliability requirement, an operation in which a UE receiving the service transmits SL HARQ feedback to a UE transmitting the service may be useful to meet the high reliability requirement.

[0093] The HARQ feedback resources may include HARQ feedback transmission resources and / or HARQ feedback reception resources. For example, the HARQ feedback transmission resources may include resources for transmitting HARQ feedback and / or resources associated with transmitting HARQ feedback. For example, the HARQ feedback reception resources may include resources for receiving HARQ feedback and / or resources associated with receiving HARQ feedback.

[0094] The PSSCH resources may include PSSCH transmission resources and / or PSSCH reception resources. For example, the PSSCH transmission resources may include resources for transmitting the PSSCH and / or resources associated with transmitting the PSSCH. For example, the PSSCH reception resources may include resources for receiving the PSSCH and / or resources associated with receiving the PSSCH.

[0095] The PSCCH resources may include PSCCH transmission resources and / or PSCCH reception resources. For example, the PSCCH transmission resources may include resources for transmitting the PSCCH and / or resources associated with transmitting the PSCCH. For example, the PSCCH reception resources may include resources for receiving the PSCCH and / or resources associated with receiving the PSCCH.

[0096] The resources may include at least one of a time domain resource, a frequency domain resource, and / or a code domain resource.

[0097] If a resource collision occurs in at least one of the PSSCH transmission, PSCCH transmission, and / or HARQ feedback transmission of the terminal, the SL HARQ feedback procedure and / or operation of the terminal may not operate correctly. For example, if a resource collision occurs in at least one of the PSSCH transmission, PSCCH transmission, and / or HARQ feedback transmission of the terminal, the SL HARQ feedback procedure and / or operation of the terminal may not be performed correctly.

[0098] If a receiving terminal successfully receives a PSSCH but an error occurs in the HARQ feedback (e.g., HARQ ACK) due to resource collision, the transmitting terminal may have to retransmit the PSSCH to the receiving terminal an additional time. For example, if a receiving terminal fails to receive a PSSCH and the HARQ feedback is not transmitted to the transmitting terminal due to resource collision, reliability or performance related to SL communication may be degraded. For example, if a receiving terminal fails to receive a PSCCH and / or PSSCH transmitted from a transmitting terminal and the HARQ NACK corresponding to the PSCCH and / or PSSCH is not correctly transmitted to the transmitting terminal due to resource collision, reliability or performance related to SL communication may be degraded. Therefore, the HARQ feedback resource needs to be determined so as to avoid or minimize collisions between multiple terminals.

[0099] The transmitting terminal may transmit the PSCCH and / or the PSSCH to the receiving terminal. For example, the transmitting terminal may transmit SL information to the receiving terminal using the PSCCH resource and / or the PSSCH resource. For example, the SL information may include at least one of SL control information, SL data, SL packets, SL TBs (Transport Blocks), SL messages, and / or SL services.

[0100] The receiving terminal can determine the HARQ feedback resource. In addition, for example, the transmitting terminal can determine the HARQ feedback resource.

[0101] The HARQ feedback resource may be configured to be associated or linked with the PSSCH. For example, the HARQ feedback resource may include at least one of a time domain resource, a frequency domain resource, and / or a code domain resource. For example, the location of the HARQ feedback resource may be configured to be associated or linked with the associated PSSCH resource. For example, the location of the HARQ feedback resource may be configured to be associated or linked with the location of the associated PSSCH resource based on a predefined function. For example, the HARQ feedback resource may be determined based on at least one of information related to the time domain associated with the PSSCH, information related to the frequency domain associated with the PSSCH, and / or information related to the code domain associated with the PSSCH.

[0102] And / or, for example, the HARQ feedback resource may be configured to have an association or linkage with the PSCCH. For example, the location of the HARQ feedback resource may be configured to have an association or linkage with the linked PSCCH resource. For example, the location of the HARQ feedback resource may be configured to have an association or linkage with the location of the linked PSCCH resource based on a predefined function. For example, the HARQ feedback resource may be determined based on at least one of information on a time domain associated with the PSCCH, information on a frequency domain associated with the PSCCH, and / or information on a code domain associated with the PSCCH.

[0103] The HARQ feedback resource may be configured in the form of a subset of frequency resources used for PSSCH transmission and / or PSCCH transmission. For example, the frequency domain of the HARQ feedback resource may be configured in the form of a subset of the frequency domain of the associated PSSCH resource and / or PSCCH resource. For example, the frequency domain of the HARQ feedback resource may be included in the frequency domain of the PSSCH resource and / or PSCCH resource.

[0104] FIG. 10 illustrates an example of resources for transmitting HARQ feedback on the NR sidelink.

[0105] 10, a transmitting terminal may transmit a PSCCH and / or a PSSCH to a receiving terminal on four subchannels. In this case, the frequency domain of the HARQ feedback resource associated with the PSCCH and / or PSSCH may be a subset of the frequency resources used by the transmitting terminal to transmit the PSCCH and / or PSSCH.

[0106] A time gap between the HARQ feedback resource and the PSSCH resource may be configured. And / or, for example, a time gap between the HARQ feedback resource and the PSCCH resource may be configured. For example, taking into consideration the decoding capability and / or delay requirements (e.g., V2X message and / or service-related delay requirements) of the terminal, a time gap may be configured between the time when the receiving terminal receives the PSSCH and / or PSCCH and the time when the receiving terminal transmits the HARQ feedback. For example, taking into consideration the decoding capability and / or delay requirements of the terminal, a time gap may be configured between the time when the transmitting terminal receives the HARQ feedback and the time when the transmitting terminal (re-)transmits the PSSCH and / or PSCCH.

[0107] The time gap may be commonly configured within a resource pool. For example, the time gap may be commonly configured among different terminals within a resource pool. For example, the time gap may be commonly configured for the transmitting terminal and the receiving terminal. Therefore, terminals can easily determine HARQ feedback resources. For example, the time gap may be resource-pool-specifically configured.

[0108] The time gap may be set or specified to be smaller than and / or equal to the smallest latency budget of services coexisting on the resource pool. For example, if service A and service B coexist on the resource pool and the latency budget of service A is smaller than the latency budget of service B, the time gap may be set or specified to be smaller than or equal to the latency budget of service A.

[0109] The time gap may be specified such that a maximum number of Transport Block (TB)-related retransmissions configured for a resource pool, a service type, a service priority, a broadcast type, and / or a service's QoS requirements can be supported / performed within the delay budget for the (associated) services on the resource pool. For example, the maximum number of retransmissions may be the maximum number of allowed retransmissions, including the initial transmission.

[0110] The time gap may be set or specified to be greater than and / or equal to the largest value among the decoding capabilities of the terminals. Here, for example, the decoding capability may be the terminal processing time required from the end / end of PSSCH reception of the terminal to the start of PSFCH transmission of the terminal. And / or, for example, the decoding capability may be the terminal processing time required from the end / end of PSCCH reception of the terminal to the start of PSFCH transmission of the terminal. For example, the time gap may be set or specified to be greater than and / or equal to the largest value among the decoding capabilities of the terminals in a resource pool. For example, if terminal A, terminal B, and terminal C perform SL communication in a resource pool and terminal A has the worst decoding capability, the time gap may be set or specified to be greater than or equal to the processing time required from the end / end of PSSCH and / or PSCCH reception of terminal A to the start of PSFCH transmission of terminal A.

[0111] The time gap may be set differently or independently for each of a service type, a service priority, a SL communication type, a service-related session, a service-related PPPP, a service-related PPPR, a service-related target Block Error Rate (BLER), a service-related target Signal to Interference plus Noise Ratio (SINR), a service-related delay budget, and / or a terminal capability. For example, the time gap may be set differently or independently for each of a service type, a service priority, a SL communication type, a service-related session, a service-related PPPP, a service-related PPPR, a service-related target BLER, a service-related target SINR, a service-related delay budget, and / or a terminal capability within a resource pool. For example, the SL communication type may include at least one of unicast, groupcast, and / or broadcast.

[0112] The receiving terminal may transmit HARQ feedback to the transmitting terminal. For example, the receiving terminal may transmit HARQ feedback corresponding to the PSCCH and / or PSSCH to the transmitting terminal. For example, the receiving terminal may transmit the HARQ feedback to the transmitting terminal using HARQ feedback resources determined based on the PSCCH resources and / or PSSCH resources. For example, the transmitting terminal may receive HARQ feedback from the receiving terminal on HARQ feedback resources determined based on the PSCCH resources and / or PSSCH resources.

[0113] If the receiving terminal successfully receives the PSCCH and / or the PSSCH, the HARQ feedback may be a HARQ ACK. For example, if the receiving terminal fails to receive the PSCCH and / or the PSSCH, the HARQ feedback may be at least one of a HARQ NACK and / or a discontinuous detection (DTX).

[0114] In the case of groupcast, in which multiple terminals in a group perform SL communication with each other, the HARQ feedback resource may be embodied in two forms.

[0115] (1) Option A: A common HARQ feedback resource may be configured among receiving terminals. For example, when a transmitting terminal transmits a PSSCH and / or a PSCCH to multiple receiving terminals, a common HARQ feedback resource may be configured for the multiple receiving terminals that receive the PSSCH and / or the PSCCH.

[0116] (2) Option B: Different or independent HARQ feedback resources may be configured between receiving terminals. For example, different or independent HARQ feedback resources may be configured for each receiving terminal or for each subgroup including one or more receiving terminals. For example, when a transmitting terminal transmits PSSCH and / or PSCCH to multiple receiving terminals, different or independent HARQ feedback resources may be configured for each of multiple receiving terminals or multiple subgroups that receive the PSSCH and / or PSCCH.

[0117] Option A may be applied only to the groupcast option 1. For example, in groupcast option 1, multiple receiving terminals can transmit a HARQ NACK to a transmitting terminal using a HARQ feedback resource commonly configured for the multiple receiving terminals only when they fail to receive a PSCCH and / or a PSSCH. For example, the HARQ NACK may be implemented in the form of a single frequency network (SFN). In this case, the transmitting terminal may not be able to separately receive HARQ NACKs transmitted by multiple receiving terminals. Therefore, the transmitting terminal may not know which receiving terminals have transmitted a HARQ NACK. However, the transmitting terminal can know that at least one receiving terminal among the multiple receiving terminals has transmitted a HARQ NACK, and the transmitting terminal can retransmit the PSCCH and / or PSSCH to the multiple receiving terminals.

[0118] In Option A, the unicast-related HARQ feedback resource structure may be reused. And / or, for example, in Option A, overhead associated with the HARQ feedback resource may be reduced. On the other hand, in Option A, there is a limitation that the transmitting terminal cannot distinguish / recognize DTX. For example, when the transmitting terminal transmits the PSSCH and / or the PSCCH to the receiving terminal, the receiving terminal may fail to receive the PSCCH that schedules the PSSCH. In this case, according to Option A, the receiving terminal may not transmit a HARQ NACK to the transmitting terminal. This may cause a problem in which the transmitting terminal mistakenly believes that the receiving terminal has successfully received the PSSCH.

[0119] In Option B, different or independent HARQ feedback resources may be allocated to each receiving terminal or subgroup within a group including multiple receiving terminals. Here, for example, according to Option B, the greater the number of receiving terminals or subgroups included in the group, the greater the amount of HARQ feedback resources may be required. For example, for a group including N receiving terminals, N-1 HARQ feedback resources may be required. For example, Option B may be applied only to Groupcast Option 2.

[0120] FIG. 11 shows an example of a procedure for transmitting and receiving HARQ feedback for PSCCH and / or PSSCH.

[0121] 11, multiple receiving terminals may transmit HARQ feedback to a transmitting terminal, respectively. For example, multiple receiving terminals may transmit HARQ feedback corresponding to the PSCCH and / or PSSCH to a transmitting terminal, respectively. Multiple receiving terminals may transmit the HARQ feedback to a transmitting terminal using HARQ feedback resources determined based on the PSCCH resources and / or PSSCH resources.

[0122] If the receiving terminal successfully receives the PSCCH and / or the PSSCH, the HARQ feedback may be a HARQ ACK. For example, if the receiving terminal fails to receive the PSCCH and / or the PSSCH, the HARQ feedback may be at least one of a HARQ NACK and / or a discontinuous detection (DTX).

[0123] The terminal can determine the HARQ feedback transmit power based on at least one of an SL path loss value derived / obtained based on a reference signal on the SL channel, an SL RSRP value derived / obtained based on a reference signal on the SL channel, an SL RSRQ value derived / obtained based on a reference signal on the SL channel, an open-loop power control parameter, and / or a closed-loop power control parameter. For example, when the transmitting terminal transmits a reference signal to the receiving terminal over the SL channel, the receiving terminal can determine the HARQ feedback transmit power based on at least one of an SL path loss value derived / obtained based on a reference signal on the SL channel, an SL RSRP value derived / obtained based on a reference signal on the SL channel, an SL RSRQ value derived / obtained based on a reference signal on the SL channel, an open-loop power control parameter, and / or a closed-loop power control parameter.

[0124] The reference signal on the SL channel may be predefined. The predefined reference signal on the SL channel may be a DMRS transmitted on a PSSCH (i.e., a PSSCH DMRS) or a DMRS transmitted on a PSCCH (i.e., a PSCCH DMRS). The reference signal on the SL channel may be a CSI-RS transmitted on a PSSCH. The predefined reference signal on the SL channel may be a reference signal used for estimating the quality of the SL channel (e.g., a CQI, a PMI, and an RI). For example, the reference signal on the SL channel may be a reference signal used for measuring at least one of an SL path loss value, an SL RSRP value, and / or an SL RSRQ value.

[0125] The predefined SL path loss may be a path loss for a link between the transmitting terminal and the receiving terminal. For example, open-loop power control parameters and / or closed-loop power control parameters may be pre-configured. For example, the open-loop power control parameters may include Po and / or alpha values.

[0126] Po may be a power control parameter for satisfying a packet / message transmission-related target error rate (e.g., Block Error Rate (BLER), Frame Error Rate (FER)) on average. And / or, for example, Po may be a power control parameter related to the average received SINR of a transmitting terminal and a receiving terminal. For example, Po may be a power control parameter specific to a terminal, a resource pool, a service type, a service priority, a QoS requirement related to a service, a (frequency) resource size used for SL transmission, an MCS value used for SL transmission, a resource pool-related congestion level (e.g., CBR), and / or a cast type. For example, when the HARQ feedback transmission power is calculated / derived based on the SL RSRP and / or SL RSRQ value / range, different Po values / ranges may be mapped / set for each (pre-configured) SL RSRP and / or SL RSRQ value / range.

[0127] When the HARQ feedback transmit power is derived / calculated based on the SL path loss, the alpha value may be a weight applied to the (measured) path loss compensation. And / or when the HARQ feedback transmit power is calculated / derived based on the SL RSRP and / or SL RSRQ value / range, the alpha value may be a weight applied to the (measured) SL RSRP and / or SL RSRQ value / range. And / or when the HARQ feedback transmit power is calculated / derived based on the SL RSRP and / or SL RSRQ value / range, the alpha value may be a weight applied to the HARQ feedback transmit power mapped / configured for each (measured) SL RSRP and / or SL RSRQ value / range. Here, the alpha value / range may be set specifically for the UE, resource pool, service type, service priority, QoS requirements associated with the service, (frequency) resource size used for SL transmission, MCS value used for SL transmission, resource pool-related congestion level (e.g., CBR), and / or type of channel. When the HARQ feedback transmission power is calculated / derived based on the SL RSRP and / or SL RSRQ value / range, different alpha values / ranges may be mapped / set for each (pre-configured) SL RSRP and / or SL RSRQ value / range.

[0128] When the HARQ feedback transmit power is calculated / derived based on the SL RSRP and / or SL RSRQ value / range, different offset values / ranges may be mapped / configured for each (pre-configured) SL RSRP and / or SL RSRQ value / range. A UE that has measured the SL RSRP and / or SL RSRQ may determine the final HARQ feedback transmit power by applying an offset associated with the SL RSRP value and / or SL RSRQ value to the (pre-configured normalized or nominal) SL (HARQ feedback) (maximum) transmit power. Here, for example, the offset value / range may be configured specifically for the UE, resource pool, service type, service priority, QoS requirements associated with the service, the (frequency) resource size used for SL transmission, the MCS value used for SL transmission, the resource pool-related congestion level (e.g., CBR), and / or the type of broadcast.

[0129] Different (normalized or nominal) (maximum) HARQ feedback transmit power values / ranges may be mapped / configured for each SL RSRP and / or SL RSRQ value / range. For example, the (normalized or nominal) (maximum) HARQ feedback transmit power value / range may be configured specifically for a terminal, a resource pool, a type of service, a priority of the service, a QoS requirement associated with the service, a (frequency) resource size used for SL transmission, an MCS value used for SL transmission, a resource pool-related congestion level (e.g., CBR), and / or a type of broadcast.

[0130] The reference signal and / or a transmission power value associated with the SL channel including the reference signal may be signaled to a terminal on a predefined channel. A transmitting terminal may transmit the reference signal and / or a transmission power value associated with the SL channel including the reference signal to a receiving terminal on a predefined channel. The predefined channel may be a PSCCH. The receiving terminal may be a terminal that measures at least one of SL path loss, SL RSRP, and / or SL RSRQ based on the reference signal.

[0131] The open-loop power control parameters (and / or the (maximum or minimum) HARQ feedback transmit power values ​​mapped / set for each SL RSRP (and / or SL RSRQ) value / range) may be set differently or independently for each service type, service priority, SL communication type (e.g., unicast, groupcast, broadcast), (resource pool-related) congestion level (e.g., CBR (Channel Busy Ratio)), session associated with the service, PPPP associated with the service, PPPR associated with the service, target Block Error Rate (BLER) associated with the service, target Signal to Interference plus Noise Ratio (SINR) associated with the service, (minimum or maximum) target communication distance associated with the service, and / or delay budget associated with the service. And / or, for example, the closed-loop power control operation / parameters may be operated / configured differently or independently for each type of service, priority of the service, type of SL communication (e.g., unicast, groupcast, broadcast), (resource pool-related) congestion level (e.g., CBR), session associated with the service, PPPP associated with the service, PPPR associated with the service, target Block Error Rate (BLER) associated with the service, target Signal to Interference plus Noise Ratio (SINR) associated with the service, target communication distance (minimum or maximum) associated with the service, and / or delay budget associated with the service.

[0132] Open-loop power control parameters associated with the HARQ feedback may be configured differently or independently from the open-loop power control parameters associated with the PSSCH and / or PSCCH, and / or closed-loop power control operations / parameters associated with the HARQ feedback may be operated / configured differently or independently from the closed-loop power control operations / parameters associated with the PSSCH and / or PSCCH.

[0133] FDM of HARQ feedback resources may be allowed or configured only for receiving terminals whose distance difference from the transmitting terminal receiving the HARQ feedback is within a predetermined threshold; and / or FDM of HARQ feedback resources may be allowed or configured only for receiving terminals whose SL path loss difference for the link between the transmitting terminal and the receiving terminal is within a predetermined threshold; and / or FDM of HARQ feedback resources may be allowed or configured only for receiving terminals whose SL RSRP difference for the link between the transmitting terminal and the receiving terminal is within a predetermined threshold; and / or FDM of HARQ feedback resources may be allowed or configured only for receiving terminals whose SL RSRQ difference for the link between the transmitting terminal and the receiving terminal is within a predetermined threshold.

[0134] If a distance difference between a plurality of receiving terminals and a transmitting terminal is within a predetermined threshold, the plurality of receiving terminals can transmit HARQ feedback on FDM resources on the frequency axis. And / or if a path loss difference between a plurality of receiving terminals and a transmitting terminal is within a predetermined threshold, the plurality of receiving terminals can transmit HARQ feedback on FDM resources on the frequency axis. And / or if a (measured) RSRP value difference between a plurality of receiving terminals and a transmitting terminal is within a predetermined threshold, the plurality of receiving terminals can transmit HARQ feedback on FDM resources on the frequency axis. And / or if a (measured) RSRQ value difference between a plurality of receiving terminals and a transmitting terminal is within a predetermined threshold, the plurality of receiving terminals can transmit HARQ feedback on FDM resources on the frequency axis.

[0135] It may not be preferable to FDM HARQ feedback resources between terminals or subgroups within a group. When HARQ feedback transmission-related power control is not applied, it may not be preferable to FDM HARQ feedback resources between different terminals or different subgroups within a group. When the HARQ feedback reception power difference between different terminals or different subgroups within a group is greater than a preset threshold, it may not be preferable to FDM HARQ feedback resources between different terminals or different subgroups within a group. When the SL path loss difference between different terminals or different subgroups within a group is greater than a preset threshold, it may not be preferable to FDM HARQ feedback resources between different terminals or different subgroups within a group. When the SL RSRP difference between different terminals or different subgroups within a group is greater than a preset threshold, it may not be preferable to FDM HARQ feedback resources between different terminals or different subgroups within a group. If the SL RSRQ difference between different terminals or different subgroups in a group is greater than a preset threshold, it may not be preferable to FDM the HARQ feedback resources between different terminals or different subgroups in the group.

[0136] As in the above example, when it is not preferable to FDM the HARQ feedback resource, the HARQ feedback resource may be pseudo-randomly TDMed based on at least one of the GUE_ID, the receiving terminal-associated identifier, the SL HARQ process ID, and / or the transmitting terminal-associated identifier. The HARQ feedback resource may be pseudo-randomly determined based on at least one of the GUE_ID, the receiving terminal-associated identifier, the SL HARQ process ID, and / or the transmitting terminal-associated identifier. For example, the HARQ feedback resource may be TDMed or determined by a function having at least one of the GUE_ID, the receiving terminal-associated identifier, the SL HARQ process ID, and / or the transmitting terminal-associated identifier as an input parameter. The HARQ feedback resource may be a HARQ feedback resource for each of a plurality of terminals in a group. The HARQ feedback resource may be a HARQ feedback resource for each of subgroups in a group. For example, the receiving terminal-associated identifier may be a destination ID. The sending terminal related identifier may be a source ID. The function may be predefined.

[0137] The transmitting terminal can transmit a PSCCH and / or a PSSCH to the receiving terminal. The transmitting terminal can transmit SL information to the receiving terminal using a PSCCH resource and / or a PSSCH resource. The SL information can include at least one of SL control information, SL data, SL packets, SL Transport Blocks (TBs), SL messages, and / or SL services.

[0138] The receiving terminal can determine the HARQ feedback resource. Furthermore, the transmitting terminal can determine the HARQ feedback resource. For example, the receiving terminal may be any one of a plurality of terminals performing groupcast communication within a group.

[0139] The HARQ feedback resource may be determined based on at least one of the PSCCH resource, the PSSCH resource, and / or a GUE_ID. When multiple receiving terminals in a group feed back HARQ ACK or HARQ NACK to a transmitting terminal using different PSFCH resources, the multiple receiving terminals in the group can determine the HARQ feedback resource using a GUE_ID. The resource may include at least one of a time domain resource, a frequency domain resource, and / or a code domain resource. The GUE_ID may be information for identifying terminals in the group.

[0140] The receiving terminal may transmit HARQ feedback to the transmitting terminal. The receiving terminal may transmit HARQ feedback corresponding to the PSCCH and / or PSSCH to the transmitting terminal. For example, the receiving terminal may transmit the HARQ feedback to the transmitting terminal using a HARQ feedback resource determined based on at least one of the PSCCH resource, the PSSCH resource, and / or GUE_ID.

[0141] If the receiving terminal successfully receives the PSCCH and / or the PSSCH, the HARQ feedback may be a HARQ ACK. If the receiving terminal fails to receive the PSCCH and / or the PSSCH, the HARQ feedback may be at least one of a HARQ NACK and / or a discontinuous detection (DTX).

[0142] When a transmitting terminal selects PSSCH and / or PSCCH transmission resources through a sensing operation, a problem of collision of HARQ feedback transmission related resources does not occur. When multiple transmitting terminals select different PSSCH and / or PSCCH transmission resources through a sensing operation, the HARQ feedback resource may be determined based on the PSSCH resource and / or PSCCH resource. Therefore, collision of HARQ feedback resources can be automatically avoided between terminals that select different PSSCH and / or PSCCH transmission resources through a sensing operation.

[0143] When a transmitting terminal transmits the same PSSCH and / or PSCCH to multiple receiving terminals in a group, the multiple receiving terminals can determine HARQ feedback resources using different GUE_IDs, thereby preventing collision of HARQ feedback resources even when multiple receiving terminals in a group receive the same PSSCH and / or PSCCH.

[0144] FIG. 12 shows an example of a procedure for transmitting and receiving HARQ feedback for PSCCH and / or PSSCH in groupcast SL communication.

[0145] Referring to FIG. 12, IDs for identifying terminals within a group may be assigned / assigned to multiple terminals within the group. The IDs may be referred to as inner IDs. The inner IDs may be an application or parameter such as GUE_ID. For example, for specific groupcast traffic, an application layer may transmit information regarding the inner IDs of terminals and information regarding the number of terminals in the group to the V2X layer. The terminal may be the terminal transmitting the specific groupcast traffic. For specific groupcast traffic, the application layer may not transmit information regarding the inner IDs of other terminals in the group to the V2X layer. The groupcast traffic may include at least one of a groupcast service, groupcast data, groupcast packets, and / or groupcast messages.

[0146] When a transmitting terminal intends to transmit first traffic related to groupcast to multiple receiving terminals in a group, the application layer of the transmitting terminal can transmit information regarding the internal ID of the transmitting terminal and information regarding the number of terminals in the group to the V2X layer of the transmitting terminal. The application layer of receiving terminal 1 can transmit information regarding the internal ID of receiving terminal 1 and information regarding the number of terminals in the group to the V2X layer of the receiving terminal 1. The application layer of receiving terminal 2 can transmit information regarding the internal ID of receiving terminal 2 and information regarding the number of terminals in the group to the V2X layer of the receiving terminal 2. The application layer of receiving terminal 3 can transmit information regarding the internal ID of receiving terminal 3 and information regarding the number of terminals in the group to the V2X layer of the receiving terminal 3. The application layer of receiving terminal 4 can transmit information regarding the internal ID of receiving terminal 4 and information regarding the number of terminals in the group to the V2X layer of the receiving terminal 4.

[0147] The V2X layer of the terminal may transmit information about the internal ID of the terminal and information about the number of terminals in the group to the AS layer of the terminal. For example, the V2X layer of the terminal may also transmit L2 ID (e.g., source L2 ID, destination L2 ID) and / or QoS information to the AS layer of the terminal.

[0148] The transmitting terminal may transmit specific groupcast traffic to a plurality of receiving terminals (S2110). The specific groupcast traffic may be transmitted on the PSSCH and / or the PSCCH.

[0149] The receiving terminals may determine HARQ feedback resources (S2120). The receiving terminals (e.g., AS layers of the receiving terminals) may determine HARQ feedback resources for specific groupcast traffic based on information about their own internal IDs and information about the number of terminals in the group according to a predefined rule.

[0150] The transmitting terminal can determine the HARQ feedback resource (that it should receive). The transmitting terminal can derive or determine the HARQ feedback resource of the plurality of receiving terminals associated with specific groupcast traffic based on information about its internal ID and information about the number of terminals in the group.

[0151] When the application layer provides information about the internal ID of the terminal and information about the number of terminals in the group to the V2X layer of the terminal, the terminal can determine or consider either the groupcast option 1 or the groupcast option 2 as a (selectable) HARQ feedback option for the specific groupcast traffic. The V2X layer of the terminal can determine or consider either the groupcast option 1 or the groupcast option 2 as a (selectable) HARQ feedback option for the specific groupcast traffic. Furthermore, depending on whether a preset condition is met, the terminal can finally determine or consider either the groupcast option 1 or the groupcast option 2 as the HARQ feedback option for the specific groupcast traffic. When respective HARQ feedback resources for multiple terminals participating in groupcast are all supported in a resource pool, the terminal can finally determine or consider the groupcast option 2 as the HARQ feedback option for the specific groupcast traffic. If the resource pool does not support all HARQ feedback resources for multiple terminals participating in groupcast, the terminal may ultimately determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast traffic. This determination may be made in the AS layer of the terminal.

[0152] If an application layer does not provide information regarding the number of terminals in a group to a V2X layer of a terminal, the terminal can determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast traffic. If an application layer does not provide information regarding an internal ID of the terminal and / or information regarding the number of terminals in a group to a V2X layer of a terminal, the terminal can determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast traffic. For example, the V2X layer of the terminal can determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast traffic.

[0153] When the application layer and / or V2X layer provides information about the internal ID of the terminal and information about the number of terminals in the group to the AS layer of the terminal, the terminal can determine or consider either the groupcast option 1 or the groupcast option 2 as a (selectable) HARQ feedback option for the specific groupcast traffic. The AS layer of the terminal can determine or consider either the groupcast option 1 or the groupcast option 2 as a (selectable) HARQ feedback option for the specific groupcast traffic. Furthermore, depending on whether a preset condition is met, the terminal can finally determine or consider either the groupcast option 1 or the groupcast option 2 as the HARQ feedback option for the specific groupcast traffic. When respective HARQ feedback resources for multiple terminals participating in groupcast are all supported in a resource pool, the terminal can finally determine or consider the groupcast option 2 as the HARQ feedback option for the specific groupcast traffic. If the resource pool does not support all HARQ feedback resources for multiple terminals participating in groupcast, the terminal may ultimately determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast traffic. This determination may be made in the AS layer of the terminal.

[0154] If the application layer and / or V2X layer does not provide information regarding the number of terminals in a group to the AS layer of the terminal, the terminal can determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast traffic. If the application layer and / or V2X layer does not provide information regarding the internal ID of the terminal and / or information regarding the number of terminals in a group to the AS layer of the terminal, the terminal can determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast traffic. For example, the AS layer of the terminal can determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast traffic.

[0155] In a resource pool specific manner, whether or not at least one of Groupcast Option 1 and / or Groupcast Option 2 is supported may be signaled to the terminal. In a resource pool specific manner, whether or not at least one of Groupcast Option 1 and / or Groupcast Option 2 is supported may be signaled to the terminal on a service type, a cast type, or a QoS requirement basis. In a resource pool specific manner, whether or not PSFCH resources associated with Groupcast Option 1 are configured may be signaled to the terminal on a service type, a cast type, or a QoS requirement basis. In a resource pool specific manner, whether or not PSFCH resources associated with Groupcast Option 2 are configured may be signaled to the terminal on a service type, a cast type, or a QoS requirement basis.

[0156] The transmitting terminal can receive HARQ feedback from multiple receiving terminals. The transmitting terminal can receive groupcast option 1-based HARQ feedback from multiple receiving terminals. For example, the transmitting terminal can receive groupcast option 2-based HARQ feedback from multiple receiving terminals.

[0157] A specific groupcast option-based HARQ feedback operation may be required for specific groupcast traffic. If a reliability requirement associated with a service is high, when a transmitting terminal transmits the service to a receiving terminal, the receiving terminal must perform a groupcast option 2-based HARQ feedback operation. If the receiving terminal performs a groupcast option 1-based HARQ feedback operation for the service, a DTX problem may occur. Therefore, the receiving terminal must perform a groupcast option 2-based HARQ feedback operation for a service with a high reliability requirement. The DTX problem may occur when the receiving terminal fails to receive the PSCCH and does not send a NACK to the transmitting terminal, causing the transmitting terminal to mistakenly believe that the receiving terminal has successfully received the PSCCH and PSSCH. The DTX problem may cause the reliability requirement of the service to not be met. Therefore, if a specific groupcast option is not supported in the resource pool, the transmitting terminal may perform a blind retransmission operation if the specific groupcast option is not supported for the traffic and / or service. If a PSFCH resource associated with a specific groupcast option is not configured, the transmitting terminal may perform a blind retransmission operation. The transmitting terminal can perform retransmission without receiving HARQ feedback from the receiving terminal.

[0158] An example of the configuration of PSCCH / PSSCH / PSFCH in a slot is shown in Fig. 13. Referring to Fig. 13, the time position of the PSFCH in one slot may be TDM'd with the PSCCH / PSSCH.

[0159] Figure 14 illustrates the structure of a sidelink SSB (S-SSB). Referring to Figure 14, a terminal can transmit an S-SSB to synchronize with other terminals on the sidelink. Figure 14 shows the order of symbols to which a sidelink primary synchronization signal (S-PSS), a sidelink secondary synchronization signal (S-SSS), and a physical sidelink broadcast channel (PSBCH) are mapped within the S-SSB.

[0160] FIG. 15 illustrates a method for determining PSFCH resources by a sidelink terminal.

[0161] FIG. 15 shows a situation in which a PSFCH period of 4 slots, a minimum time gap from PSSCH reception to PSFCH transmission of 2 slots, PSFCH resource types according to the number of PSSCH subchannels, and two cyclic shift (CS) pairs are configured in the upper layer. FIG. 15 also shows a situation in which a PSSCH transmitting terminal transmits PSSCH (i.e., PSSCH 2 and PSSCH 6) using two subchannels in the second slot. In this situation, the PSFCH transmitting terminal selects 10 PRBs and 2 CS pairs corresponding to numbers 2 and 6, i.e., a total of 20 candidate resources (i.e., R PSFCH PRB,cs The appropriate resource can be determined from the available resources (Tx ID or P_ID) mod 20 according to the ID of the transmitting terminal (Tx ID or P_ID) and the ID of the receiving terminal (Rx ID or M_ID). This figure shows a situation where 17 is obtained as a result of (Tx ID + Rx ID) mod 20 according to 3GPP TS 38.213, indicating that the third PRB and the second CS pair (i.e., CS=3 for NACK and CS=9 for ACK) of the sixth PRB group are used for PSFCH transmission. The value of Rx ID is set to 0 in cases other than groupcast, which requires ACK / NACK feedback.

[0162] <Communication methods in unlicensed spectrum>

[0163] FIG. 16 illustrates an example of an NR-U (NR-Unlicensed) service environment.

[0164] Referring to Figure 16, a service environment in which NR technology 11 in a licensed spectrum and NR-U, which is NR technology 12 in an unlicensed spectrum, are integrated may be provided to users. For example, in an NR-U environment, NR technology 11 in a licensed spectrum and NR technology 12 in an unlicensed spectrum may be integrated using techniques such as carrier aggregation, which can contribute to network capacity expansion. Also, in an asymmetric traffic structure in which downlink data is relatively larger than uplink data, NR-U can provide NR services optimized according to various requirements or environments. For convenience, NR technology in a licensed spectrum is referred to as NR-L (NR-Licensed), and NR technology in an unlicensed spectrum is referred to as NR-U (NR-Unlicensed).

[0165] Figure 17 shows an existing communication system (e.g., wireless LAN) that operates in unlicensed bands. Devices that operate in unlicensed bands usually operate on a Listen-Before-Talk (LBT) basis, and perform Clear Channel Assessment (CCA) to sense the channel before transmitting data.

[0166] Referring to Figure 17, a WLAN device (e.g., AP, STA) performs carrier sensing before transmitting data to check whether a channel is busy. If a wireless signal of a certain strength or higher is detected from a channel to which data is to be transmitted, the channel is determined to be busy, and the WLAN device delays access to the channel. This process is called clear channel assessment, and the signal level that determines whether a signal is detected is called a CCA threshold. On the other hand, if no wireless signal is detected from the channel or a wireless signal of a strength lower than the CCA threshold is detected, the channel is determined to be idle.

[0167] If a channel is determined to be idle, a terminal with data to transmit performs a backoff procedure after a defer duration (e.g., Arbitration InterFrame Space (AIFS), PCF IFS (PIFS), etc.). The defer duration refers to the minimum time a terminal must wait after a channel becomes idle. The backoff procedure allows a terminal to wait any additional time after the defer deadline. For example, a terminal waits by decreasing a slot time equal to a random number assigned to the terminal within a contention window (CW) while the channel is idle, and a terminal that has exhausted all slot times can attempt to access the channel.

[0168] If the terminal successfully accesses the channel, it can transmit data through the channel. If the data transmission is successful, the contention window size (CWS) is reset to its initial value (CWmin). On the other hand, if the data transmission fails, the CWS is doubled. This assigns the terminal a new random number within a range twice the previous random number range and performs a backoff procedure in the next CW. In WLAN, only ACK is defined as reception response information for data transmission. Therefore, if an ACK is received for data transmission, the CWS is reset to its initial value, and if no feedback information is received for data transmission, the CWS is doubled.

[0169] As mentioned above, since existing communications in unlicensed bands mostly operate on the LBT basis, channel access in the NR-U system also performs LBT for coexistence with existing devices. Specifically, channel access methods in unlicensed bands in NR can be divided into the following four categories depending on whether or not LBT is used / applied.

[0170] ●Category 1: No LBT

[0171] - The Tx entity does not perform the LBT procedure for transmission.

[0172] Category 2: LBT without random backoff

[0173] The Tx entity senses whether the channel is idle during a first interval without random backoff in order to transmit. That is, the Tx entity can transmit on the channel immediately after sensing the channel as idle during the first interval. The first interval is an interval of a pre-configured length immediately before the Tx entity transmits. According to one embodiment, the first interval may be 25 us long, but the present invention is not limited thereto.

[0174] Category 3: LBT with random backoff using a fixed-size CW

[0175] The Tx entity obtains a random number within a fixed-size CW, sets it as the initial value of a backoff counter (or backoff timer) N, and performs backoff using the set backoff counter N. That is, in the backoff procedure, the Tx entity decrements the backoff counter by one each time the channel is sensed as idle during a pre-set slot period. Here, the pre-set slot period may be 9 us, but the present invention is not limited thereto. The backoff counter N is decremented by one from its initial value, and when the value of the backoff counter N reaches 0, the Tx entity can transmit. Meanwhile, to perform backoff, the Tx entity first senses whether the channel is idle during a second interval (i.e., a defer period Td). According to an embodiment of the present invention, the Tx entity can sense (or determine) whether the channel is idle during the second interval depending on whether the channel is idle during at least a portion of the second interval (e.g., one slot period). The second interval may be set based on the channel access priority class of the Tx entity and consists of a period of 16 us and m consecutive slot periods, where m is the value set by the channel access priority class. If the Tx entity senses the channel as idle during the second interval, it performs channel sensing to decrease the backoff counter. On the other hand, if the channel is sensed as occupied during the backoff procedure, the backoff procedure is aborted. After aborting the backoff procedure, the Tx entity can resume backoff if the channel is sensed as idle during an additional second interval. In this way, the Tx entity can transmit if the channel is idle for the second interval plus the slot period of the backoff counter N. In this case, the initial value of the backoff counter N is obtained within a fixed-size CW.

[0176] Category 4: LBT with random backoff using variable-size CW

[0177] - The Tx entity obtains a random number within a variable-size CW, sets it as the initial value of a backoff counter (or backoff timer) N, and performs backoff using the set backoff counter N. More specifically, the Tx entity can adjust the size of the CW based on HARQ-ACK information for the previous transmission, and the initial value of the backoff counter N is obtained within the CW of the adjusted size. The specific process by which the Tx entity performs backoff is as described in Category 3. The Tx entity can transmit if the channel is idle for the second interval plus the slot period of the backoff counter N. In this case, the initial value of the backoff counter N is obtained within a variable-size CW.

[0178] In the above Categories 1 to 4, the Tx entity may be a base station or a terminal. According to an embodiment of the present invention, Type 1 channel access may refer to Category 4 channel access, and Type 2 channel access may refer to Category 2 channel access, respectively.

[0179] FIG. 18 illustrates a channel access process based on Category 4 LBT according to an embodiment of the present invention.

[0180] To perform channel access, the Tx entity first performs channel sensing for the defer period Td (S302). According to an embodiment of the present invention, the channel sensing for the defer period Td in step S302 may be performed by channel sensing for at least a portion of the defer period Td. For example, the channel sensing for the defer period Td may be performed by channel sensing for one slot period within the defer period Td. The Tx entity then determines whether the channel is idle through channel sensing for the defer period Td (S304). If the channel is sensed as idle for the defer period Td, the Tx entity proceeds to step S306. If the channel is not sensed as idle for the defer period Td (i.e., sensed as occupied), the Tx entity returns to step S302. The Tx entity repeats steps S302 to S304 until the channel is sensed as idle for the defer period Td. The defer period Td may be set based on the channel access priority class of the Tx entity and consists of a period of 16 us and m consecutive slot periods, where m is the value set by the channel access priority class.

[0181] Next, the Tx entity obtains a random number within a predetermined CW, sets the random number as the initial value of a backoff counter (or backoff timer) N (S306), and proceeds to step S308. The initial value of the backoff counter N is randomly selected from a range of values ​​from 0 to CW. The Tx entity performs a backoff procedure using the set backoff counter N. That is, the Tx entity performs the backoff procedure by repeating steps S308 to S316 until the value of the backoff counter N reaches 0. Meanwhile, in FIG. 13, step S306 is performed after the channel is sensed as being idle for the defer period Td, but the present invention is not limited thereto. That is, step S306 may be performed independently of steps S302 to S304, or may be performed before steps S302 to S304. If step S306 is performed before steps S302 to S304, the Tx entity proceeds to step S308 if steps S302 to S304 sense the channel as idle for the defer period Td.

[0182] In step S308, the Tx entity determines whether the value of the backoff counter N is 0. If the value of the backoff counter N is 0, the Tx entity proceeds to step S320 and transmits. If the value of the backoff counter N is not 0, the Tx entity proceeds to step S310. In step S310, the Tx entity decrements the value of the backoff counter N by 1. According to one embodiment, the Tx entity may selectively decrement the value of the backoff counter by 1 during the channel sensing process for each slot. At this time, step S310 may be skipped at least once depending on the Tx entity's selection. Next, the Tx entity performs channel sensing for an additional slot period (S312). The Tx entity determines whether the channel is idle through channel sensing for the additional slot period (S314). If the channel is sensed as idle for the additional slot period, the Tx entity returns to step S308. In this manner, the Tx entity can decrement the backoff counter by 1 each time the channel is sensed as idle during a pre-set slot period, where the pre-set slot period may be 9 us, but the present invention is not limited thereto.

[0183] If the channel is not sensed as idle for the additional slot period in step S314 (i.e., sensed as occupied), the Tx entity proceeds to step S316. In step S316, the Tx entity determines whether the channel is idle for the additional defer period Td. According to an embodiment of the present invention, the channel sensing in step S316 may be performed on a slot-by-slot basis. That is, the Tx entity determines whether the channel is sensed as idle for the entire slot period of the additional defer period Td. If an occupied slot is detected within the additional defer period Td, the Tx entity immediately resumes step S316. If the channel is sensed as idle for the entire slot period of the additional defer period Td, the Tx entity returns to step S308.

[0184] On the other hand, if the value of the backoff counter N is confirmed as 0 in step S308, the Tx entity performs transmission (S320). The Tx entity receives HARQ-ACK feedback corresponding to the transmission (S322). The Tx entity can determine whether the previous transmission was successful based on the received HARQ-ACK feedback. Next, the Tx entity adjusts the CW size for the next transmission based on the received HARQ-ACK feedback (S324).

[0185] In this way, after sensing the channel as idle for the defer period Td, the Tx entity can transmit if the channel is idle for N additional slot periods. As mentioned above, the Tx entity may be a base station or a terminal, and the channel access process of FIG. 18 may be used for downlink transmissions of the base station and / or uplink transmissions of the terminal.

[0186] A channel access procedure performed by a wireless communication device in an unlicensed band will be described using Figure 19. An LBT procedure used when a wireless communication device performs channel access in an unlicensed band will be described. In particular, a channel access in which the wireless communication device performs transmission based on the result of channel sensing within a time interval of a pre-specified duration may be set for the wireless communication device. At this time, if the wireless communication device fails to access the channel, an operation method of the wireless communication device will be described. The pre-specified duration mentioned above may be 16 us.

[0187] For ease of explanation, a wireless communication device that is a wireless endpoint initiating channel occupancy is referred to as an initiating node. Furthermore, a wireless communication device that is a wireless endpoint communicating with the initiating node is referred to as a responding node. The initiating node may be a base station, and the responding node may be a mobile station. Alternatively, the initiating node may be a mobile station, and the responding node may be a base station. When the initiating node attempts to transmit data, the initiating node may perform channel access based on a channel access priority class determined according to the type of data. At this time, parameters used for channel access may be determined according to the type of data. The parameters used for channel access may include at least one of a minimum CW value, a maximum CW value, a maximum channel occupancy time (MCOT), which is the maximum duration for occupying a channel in one channel occupancy, and the number of sensing slots (mp). Specifically, the initiating node may perform the above-described Category 4 LBT based on a channel access priority class determined according to the type of data.

[0188] Table 1 below shows an example of parameter values ​​used for channel access based on channel access priority classes. Specifically, Table 1 shows parameter values ​​used for channel access for each channel access priority class for downlink transmission in the LTE LAA system.

[0189] When a downlink channel transmitted by a wireless communication device includes data traffic, a defer duration may be set based on the channel access priority class of the traffic included in the downlink channel. The defer duration may include one or more (mp) slot durations (Tsl) of an initial duration (Tf). The duration of the slot duration (Tsl) may be 9 us. The initial duration includes one idle slot duration (Tsl). The number of slot durations (mp) included in the defer duration may be set based on the channel access priority class, as described above. Specifically, the number of slot durations (mp) included in the defer duration may be set as shown in Table 4.

[0190] [Table 1]

[0191] The wireless communication device can set the range of CW values ​​according to the channel access priority class (CAPC). min,p ≦CW≦CW max,p The CW value can be set to satisfy the following. min,p ) and maximum value (CW max,p ) may be determined by the channel connection priority class. Specifically, the minimum value of CW (CW min,p ) and maximum value (CW max,p ) may be determined as shown in Table 1. Referring to FIG. 17, the wireless communication device may select a random counter value within the CW value and adjust the CW value (i.e., CW size) depending on whether channel access (or channel transmission) is successful. For example, if channel access (or channel transmission) is successful, the wireless communication device may reset the current CW value to the minimum value for each CAPC. If channel access (or channel transmission) is unsuccessful, the wireless communication device may set the current CW value to the next highest possible value within the maximum value for each CAPC.

[0192] In addition, MCOT(T mcot,p ) may be determined according to the channel access priority of the data included in the transmission, as described above. Specifically, the MCOT may be determined as shown in Table 4. As a result, the wireless communication device may not be allowed to transmit continuously in the unlicensed band for a time exceeding the MCOT. This is because the unlicensed band is a frequency band that various wireless communication devices use according to certain rules. In Table 4, when the value of the channel access priority class is p=3 or p=4 and the unlicensed band is used for a long term according to the regulations and there is no wireless communication device using other technology, the wireless communication device mcot,p = 10 ms. Otherwise, the wireless communication device mcot,p =8ms.

[0193] Table 2 shows parameter values ​​used for channel access by channel access priority class for uplink transmission used in the LTE LAA system.

[0194] [Table 2]

[0195] As shown in Table 2, the MCOT value of 6 ms may be increased to 8 ms if a transmission includes one or more gaps. A gap refers to the time from when transmission is interrupted on a carrier until transmission resumes on that carrier. In this case, the minimum duration of a gap is 100 us. The maximum duration of a transmission performed before a gap is 6 ms. The duration of a gap is not included in the channel occupancy time. When the channel access priority class value is 3 or 4 and it is guaranteed that no other wireless access technologies are used on the carrier where channel access is performed, the MCOT value may be 10 ms. In this case, other wireless access technologies may include Wi-Fi. In other cases, the MCOT value may be determined as described in Note 1 of Table 2.

[0196] The COT represents the time that a wireless communication device occupies a channel. The MCOT, as described above, represents the maximum time that an initiating node can continuously occupy a channel on any one carrier in the unlicensed band. However, as described above, gaps, which are periods when no transmission is performed, may be included between multiple transmissions. When gaps are included, the value of the MCOT may be applied differently.

[0197] <Example: Channel access for SL (sidelink) transmission>

[0198] First, the terms used in the present invention will be explained.

[0199] - Type 1 Channel Access Procedure (CAP): A channel access procedure that includes a random backoff (see FIG. 17). Within the CW, channel sensing may be performed based on a selected random value. If the channel is determined to be idle as a result of channel access, an SL transmission may be performed.

[0200] - Type 2 CAP: A channel access procedure that does not include random backoff. Channel sensing may be performed in a fixed-length sensing interval for channel transmission. It may be classified into Type 2A / 2B / 2C depending on the fixed-length sensing interval.

[0201] CO (or COT): CO means that a wireless communication device (e.g., UE) has started transmitting on the channel and is occupying the channel. COT stands for channel occupation time.

[0202] - COT sharing: This means that a COT initiated by a wireless communication device (e.g., a UE) is shared by the same / different wireless communication device (e.g., see FIG. 19).

[0203] SL transmission: SL transmission includes transmission of SL channels, such as a physical sidelink control channel (PSCCH), a physical sidelink shared channel (PSSCH), a physical sidelink feedback channel (PSFCH), and a physical sidelink broadcast channel (PSBCH).

[0204] PSCCH / PSSCH: means PSSCH and / or PSSCH.

[0205] - SCI (sidelink control information): SCI is 1 st SCI (or SCI format 1) and 2 nd It may be classified as SCI (or SCI Format 2). st SCI is transmitted via PSCCH. st SCI is (i) PSSCH and (ii) 2 on PSSCH. nd Used to schedule SCI. For example, 1 stThe SCI contains time / frequency resource information for receiving the PSSCH, a priority indicator, and nd It includes SCI format information, etc. The priority indicator indicates the traffic priority of the PSSCH. st The SCI may be decoded by all terminals in the cell for channel sensing. nd The SCI is decoded by each receiving terminal and contains the remaining information required for PSSCH decoding. nd The SCI can be transmitted using PSSCH resources. For example, nd The SCI includes a HARQ process number, a cast type indicator, a source ID, a destination ID, and the like.

[0206] Channel connection for multiple SL transmissions

[0207] 9, SL transmissions may be sent / received between multiple terminals. For example, one Tx terminal may send multiple SL transmissions to multiple Rx terminals, or multiple Rx terminals may send SL transmissions simultaneously.

[0208] Meanwhile, when performing SL transmission in an unlicensed band, the terminal may perform a channel access procedure (CAP) to transmit the SL transmission. For example, to transmit the SL transmission, the terminal may perform Type 1 CAP (see FIGS. 17 and 18). Type 1 CAP is performed according to parameters (e.g., CW) used for channel access, and the parameters used for channel access may be defined for each CAPC value (see Tables 1 and 2). The CAPC value indicates the priority of the parameters (or channel access parameters) used for channel access. For example, referring to Table 1, the CAPC value corresponds to the CW minimum value and the CW maximum value, and the larger the CAPC value, the larger the CW minimum value and the CW maximum value. As a result, the larger the CAPC value, the wider the CW range within which a counter value for random backoff is selected, and therefore the lower the channel access priority of the terminal. The CAPC value used during SL transmission may be determined based on the priority of the SL transmission.

[0209] FIG. 20 illustrates the problem when multiple SL transmissions are performed.

[0210] Referring to FIG. 20, multiple SL transmissions may be scheduled within a slot. Here, the multiple SL transmissions may be scheduled from one terminal or from two or more individual terminals. Here, the SL transmissions include transmissions of the SL channels illustrated in FIGS. 13 and 14. For example, the SL channels may include at least one of the PSCCH, PSSCH, PSFCH, and PSBCH. In this case, each SL transmission may be associated with a respective CAPC value. For example, SL transmission #1 may be associated with CAPC #a, and SL transmission #2 may be associated with CAPC #b. Here, CAPC #a and CAPC #b may be different. In this case, to transmit multiple SL transmissions, Type 1 CAP may be performed using channel access parameters with different priorities for each SL transmission. As a result, SL transmissions using channel access parameters with higher priorities may affect SL transmissions using channel access parameters with lower priorities. For example, if SL transmission #1 is successfully channel-attached and transmitted, Type 1 CAP for SL #2 may fail due to the transmission of SL transmission #1.

[0211] Hereinafter, a channel connection method for transmitting multiple SL transmissions simultaneously (for example, in one slot) will be described. To facilitate understanding of the invention, PSFCH transmission is used as an example of SL transmission. However, the present invention is also applicable to the case where channel connection is performed to transmit multiple different SL channels (see Figures 13 and 14) within one slot.

[0212] Hereinafter, the CAPC setting method when transmitting multiple PSFCHs in the same PSFCH opportunity within a slot will be described in detail for different cases. Here, the PSFCH opportunity represents the time / frequency resource for PSFCH transmission (see, for example, FIG. 10 and FIG. 15).

[0213] 1. A method for determining CAPC by a terminal when there are multiple SL channels (e.g., PSFCHs) transmitted from one terminal to different terminals

[0214] When one terminal transmits two or more PSFCHs to different terminals in the same PSFCH opportunity, the CAPC values ​​for each PSFCH may be set independently based on the traffic priorities corresponding to the PSFCHs transmitted from the different terminals. Therefore, the CAPC values ​​for each PSFCH may be set differently. In this case, a PSFCH transmission that has successfully achieved channel connection by setting a short CW size (i.e., a lower CAPC value = higher priority) may affect another PSFCH transmission that has a relatively long CW size (i.e., a higher CAPC value = lower priority) and performs backoff. For example, some PSFCH transmissions among two or more PSFCHs intended to be transmitted by one terminal may not occur. Therefore, when one terminal transmits two or more PSFCHs to different terminals in the same PSFCH opportunity, a CAPC setting method for resolving collisions between PSFCH transmissions in one terminal needs to be discussed.

[0215] At least one terminal may have two or more PSFCH transmissions intended to be transmitted to different terminals in the same PSFCH opportunity. Here, the priority of the PSFCH transmission inherits the traffic priority of the PSSCH corresponding to the PSFCH transmission, and the traffic priority of the PSSCH can be determined by decoding the SCI of the PSCCH. In order to resolve collisions that may occur during a channel access procedure (CAP) for PSFCH transmissions transmitted by one terminal to two or more different terminals in the same PSFCH opportunity, the following method may be considered as a CAPC setting method to be applied during the channel access procedure (CAP) for different PSFCH transmissions. During the channel access procedure (CAP) for two or more PSFCH transmissions, a single CAPC value may be commonly set to perform Type 1 channel access, and one terminal may transmit the two or more PSFCHs in the same PSFCH opportunity. In this case, the influence of PSFCH transmission from one terminal on the transmission of different PSFCHs can be minimized. This can prevent PSFCH transmission failure due to PSFCH collision, which may occur when each PSFCH transmission transmitted by one terminal uses different channel access parameters. As a method for setting one common CAPC value when performing Type 1 channel access for multiple PSFCH transmissions, when one terminal sets CAPC for each PSFCH according to the traffic priority for each PSFCH transmitted from different terminals, the highest CAPC value (i.e., the lowest priority) among the CAPC values ​​set for each PSFCH can be set as the common CAPC value. Thus, if the terminal performs a Type 1 channel access procedure before the start of a PSFCH opportunity set for itself and successfully establishes channel access, it can transmit each PSFCH to different terminals at the start of transmitting the same PSFCH. That is, if the terminal performs a Type 1 channel access procedure based on the highest CAPC value among multiple CAPC values ​​associated with multiple SL transmissions and successfully establishes channel access, it can perform multiple SL transmissions in a slot.

[0216] If channel access is not successful at the start of transmitting the same PSFCH, the terminal may drop the PSFCH. Alternatively, if channel access is not successful at the start of transmitting the same PSFCH, the terminal may transmit the PSFCH after attempting a Type 1 channel access procedure at the next PSFCH opportunity for PSFCH transmission or at a PSFCH opportunity that may be further set due to channel access failure.

[0217] As another solution, if the traffic priorities used by different UEs for PSFCH transmission in a PSFCH opportunity are unknown, a CAPC setting method for resolving collisions between PSFCH transmissions transmitted by two or more UEs may be configured to use a fixed value (e.g., lowest CAPC value = highest priority) as the CAPC value for PSFCH transmission. This may be the least complex method for resolving PSFCH collisions between different UEs.

[0218] FIG. 21 illustrates an SL transmission process according to an embodiment of the present invention.

[0219] Referring to FIG. 21 , a wireless device (e.g., a terminal) may determine a channel access priority class (CAPC) value for each of multiple sidelink (SL) transmissions within one slot (S2702). Then, to transmit the multiple SL transmissions in the one slot, the wireless device may perform a Type 1 CAP based on a maximum CAPC value among multiple CAPC values ​​associated with the multiple SL transmissions. If the Type 1 CAP is successful, the wireless device may transmit the multiple SL transmissions to corresponding receiving terminals. The multiple SL transmissions may correspond to two or more receiving terminals. Here, each CAPC value may be associated with a parameter used for channel access, and the larger the CAPC value, the lower the priority of the parameter used for the channel access. Here, the parameters used for channel access include CW parameters (see Tables 1 and 2). For example, the CW parameters may include a CW minimum value and a CW maximum value. Furthermore, the multiple SL transmissions may be scheduled for transmission on the same time resource within the one slot. Here, the plurality of SL transmissions may include a PSFCH transmission. The plurality of SL transmissions may also include a plurality of PSFCH transmissions, where the same time resource includes a PSFCH opportunity. Here, a CAPC value associated with the PSFCH transmission may be determined based on a traffic priority of a PSSCH corresponding to the PSFCH transmission. The traffic priority may also be determined based on priority information in an SCI that schedules the PSSCH.

[0220] FIG. 22 illustrates the problem that occurs when multiple SL transmissions are performed.

[0221] Referring to FIG. 22, after receiving PSCCHs / PSSCHs from multiple different terminals, the terminal may perform a process for transmitting multiple PSFCHs within a slot. In this case, each PSFCH transmission may be associated with a respective CAPC value. For example, PSFCH transmission #1 may be associated with CAPC #a, and PSFCH transmission #2 may be associated with CAPC #b. The CAPC value associated with the PSFCH transmission may be determined based on the priority of the PSFCH. The priority of the PSFCH follows the priority of the corresponding PSSCH, and the priority of the PSSCH may be determined based on priority information in the SCI that schedules the PSSCH. For convenience, it is assumed that the value of CAPC #a is greater than CAPC #b. In this case, to transmit multiple SL transmissions within a slot, the terminal may perform Type 1 CAP based on the largest CAPC value among the multiple CAPC values ​​associated with the multiple SL transmissions. If the Type 1 CAP is successful, the terminal may transmit multiple PSFCHs (to different terminals).

[0222] 2. A method for determining CAPC by a terminal when different terminals transmit PSFCHs in the same PSFCH opportunity and the CAPC values ​​for PSFCHs independently set by the different terminals are different from each other

[0223] When different terminals transmit PSFCHs in the same PSFCH opportunity, the CAPC values ​​for the PSFCHs independently set by the different terminals may be set to be different. In this case, the transmission of a terminal that successfully accesses a channel by setting a short CW size (i.e., a lower CAPC value = higher priority) may affect the transmission of another terminal that backs off by setting a relatively long CW size (i.e., a higher CAPC value = lower priority), preventing the PSFCH transmission of the terminal. Therefore, a CAPC setting method for resolving collisions that may occur during a channel access procedure (CAP) for PSFCH transmissions transmitted by at least two or more terminals in the same PSFCH opportunity needs to be discussed.

[0224] Assuming that different terminals can determine the traffic priority of the PSSCH corresponding to the PSFCH transmission at the same PSFCH opportunity by decoding the SCI of the PSCCH, two or more terminals can configure a CAPC for the two terminals to resolve collisions that may occur during the channel access procedure (CAP) for the PSFCH transmission. When performing Type 1 channel access for the PSFCH transmission, the two terminals can configure a single common CAPC value to perform Type 1 channel access. If the terminals transmit the PSFCH based on a common CAPC value, it is possible to reduce the impact on the transmission of the PSFCHs of different terminals. This can prevent PSFCH transmission failures due to PSFCH collisions that may occur when the PSFCH transmissions of the terminals use different channel access parameters of different terminals. As a method for setting a single common CAPC value for PSFCH transmission, the traffic priorities for the PSSCHs transmitted from different terminals can be determined by decoding the SCI of the PSCCH. When the CAPCs for the respective PSFCHs are set according to the traffic priorities for the respective PSSCHs, the highest CAPC value (i.e., the lowest priority) among the CAPCs set for the respective PSFCHs can be set as a single common CAPC value. This allows a Type 1 channel access procedure to be performed before the start of the same PSFCH opportunity set for different terminals. If the channel access is successful, the PSFCHs transmitted by the different terminals can be transmitted at the same start time for the PSFCH transmissions set for the different terminals. Specifically, different terminals each perform channel access at the start time for transmitting the same PSFCH, and the terminals that have successfully performed channel access can simultaneously transmit the PSFCHs.However, a terminal that fails in channel access can drop the transmission of the PSFCH, or transmit the PSFCH after attempting a Type 1 channel access procedure in the next PSFCH opportunity for PSFCH transmission or in a PSFCH opportunity that may be further set due to the channel access failure.

[0225] As another solution, if the traffic priorities used by different UEs for PSFCH transmission in a PSFCH opportunity are unknown, a CAPC setting method for resolving collisions between PSFCH transmissions transmitted by two or more UEs may be configured to use a fixed value (e.g., lowest CAPC value = highest priority) as the CAPC value for PSFCH transmission. This may be the least complex method for resolving PSFCH collisions between different UEs.

[0226] However, regardless of how the CAPC value is set for each PSFCH transmission, at least the start time of transmitting the PSFCH in the same PSFCH opportunity may be set to be cell-specific. This basically minimizes collisions between PSFCHs transmitted by different terminals or transmitted from the same terminal to different terminals. Setting the start time of PSFCH transmission within a PSFCH opportunity to be cell-specific is applicable to both a case where the same terminal transmits two or more PSFCHs to different terminals and a case where different terminals transmit different PSFCHs.

[0227] Although the methods and systems of the present invention have been described in connection with particular embodiments, some or all of their components or operations may be implemented using a computing system having a general-purpose hardware architecture.

[0228] The above description of the present invention is for illustrative purposes only, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. Therefore, the above-described embodiments should be understood to be illustrative in all respects and not restrictive. For example, each component described as a single component may be implemented in a distributed form, and similarly, each component described as a distributed component may be implemented in a combined form.

[0229] The scope of the present invention is indicated by the claims set forth below rather than by the above detailed description, and any modifications or variations derived from the meaning and scope of the claims and their equivalents should be construed as being within the scope of the present invention.

Claims

1. A terminal used in a wireless communication system, a communication module; a processor for controlling the communication module; The processor: For multiple SL (sidelink) transmissions within one slot, a CAPC (channel access priority class) value is determined for each SL transmission, In order to transmit the plurality of SL transmissions in the one slot, the terminal is configured to perform one Type 1 CAP (channel access procedure) based on a maximum CAPC value among a plurality of CAPC values ​​associated with the plurality of SL transmissions.

2. The terminal according to claim 1 , wherein the plurality of CAPC values ​​are associated with respective CW (contention window) parameters, and the larger the CAPC value, the lower the channel connection priority of the CW parameter.

3. The terminal of claim 1 , wherein the processor is configured to, if the one Type 1 CAP is successful, transmit the plurality of SL transmissions to respective corresponding receiving terminals.

4. The terminal of claim 1 , wherein the plurality of SL transmissions correspond to two or more receiving terminals.

5. The terminal of claim 1 , wherein the multiple SL transmissions are scheduled for transmission on the same time resource within the one slot.

6. The terminal of claim 1 , wherein the plurality of SL transmissions are scheduled for transmission on different frequency resources within the slot.

7. The terminal of claim 1 , wherein the plurality of SL transmissions include a physical sidelink feedback channel (PSFCH) transmission.

8. The terminal of claim 6 , wherein the plurality of SL transmissions includes a plurality of PSFCH transmissions.

9. The terminal of claim 7 , wherein the CAPC value associated with the PSFCH transmission is determined based on a traffic priority of a physical sidelink shared channel (PSSCH) corresponding to the PSFCH transmission.

10. The terminal of claim 9 , wherein the traffic priority is determined based on priority information in sidelink control information (SCI) that schedules the PSSCH.

11. 1. A method for use by a terminal in a wireless communication system, comprising: determining a channel access priority class (CAPC) value for each of a plurality of sidelink (SL) transmissions within one slot; and performing one Type 1 CAP (channel access procedure) based on a maximum CAPC value among a plurality of CAPC values ​​associated with the plurality of SL transmissions in order to transmit the plurality of SL transmissions in the one slot.

12. The method of claim 11 , wherein the plurality of CAPC values ​​are associated with respective contention window (CW) parameters, and the larger the CAPC value, the lower the channel access priority of the CW parameter.

13. The method of claim 11 , further comprising the step of, if the one Type 1 CAP is successful, transmitting the plurality of SL transmissions to respective corresponding receiving terminals.

14. The method of claim 11 , wherein the plurality of SL transmissions correspond to two or more receiving terminals.

15. The method of claim 11 , wherein the multiple SL transmissions are scheduled for transmission on the same time resource within the one slot.

16. The method of claim 11 , wherein the multiple SL transmissions are scheduled for transmission on different frequency resources within the slot.

17. The method of claim 11 , wherein the plurality of SL transmissions comprises a physical sidelink feedback channel (PSFCH) transmission.

18. 17. The method of claim 16, wherein the plurality of SL transmissions comprises a plurality of PSFCH transmissions.

19. 18. The method of claim 17, wherein the CAPC value associated with the PSFCH transmission is determined based on a traffic priority of a physical sidelink shared channel (PSSCH) corresponding to the PSFCH transmission.

20. 20. The method of claim 19, wherein the traffic priority is determined based on priority information in a sidelink control information (SCI) that schedules the PSSCH.

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