Method and apparatus for transmitting signal in wireless communication system

Abstract

The present invention relates to a wireless communication system, and in particular, to a method and a wireless device for the wireless communication system, the method comprising the steps of: determining a CAPC value for each SL transmission for a plurality of SL transmissions within a time slot; and for transmitting the plurality of SL transmissions in the time slot, performing Type 1 CAP based on a highest CAPC value of the plurality of CAPC values associated with the plurality of SL transmissions.

Description

TECHNICAL FIELD

[0001] The present application relates to a wireless communication system. In particular, the present application relates to a channel access method in a wireless communication system and a device using the same. BACKGROUND

[0002] After commercialization of fourth generation (4G) communication systems, efforts are being made to develop new fifth generation (5G) communication systems to meet the increasing demand for wireless data traffic. The 5G communication system is also called a beyond 4G network communication system, a post LTE system, or a new radio (NR) system. To achieve a high data transmission rate, the 5G communication system includes a system using a millimeter wave (mmWave) band of 6 GHz or more and a system using a frequency band of 6 GHz or less in terms of securing coverage, so that implementation in the base station and the terminal is under consideration.

[0003] The third generation partnership project (3GPP) NR system improves the spectral efficiency of the network and enables communication providers to provide more data and voice services on a given bandwidth. Accordingly, the 3GPP NR system is designed to meet the demand for high-speed data and media transmission in addition to supporting a large number of voice. The advantage of the NR system is to have a higher throughput and a lower latency on the same platform, to support frequency division duplex (FDD) and time division duplex (TDD), and to have a low operating cost due to an enhanced end user environment and a simple architecture.

[0004] For more efficient data processing, dynamic TDD of the NR system can use a method for changing the number of orthogonal frequency division multiplexing (OFDM) symbols that can be used in the uplink and the downlink according to the data traffic direction of the cell user. For example, when the downlink traffic of the cell is greater than the uplink traffic, the base station can allocate a plurality of downlink OFDM symbols to a time slot (or a subframe). Information about the time slot configuration should be transmitted to the terminal.

[0005] To mitigate path loss of radio waves and increase the transmission distance of radio waves in the mmWave band, beamforming, massive multi-input / multi-output (massive MIMO), full dimensional MIMO (FD-MIMO), array antenna, analog beamforming, hybrid beamforming combining analog beamforming and digital beamforming, and large scale antenna technology are discussed in the 5G communication system. In addition, to improve the network of the system, technologies related to evolved small cell, advanced small cell, cloud radio access network (cloud RAN), ultra-dense network, device-to-device communication (D2D), vehicle-to-everything communication (V2X), wireless backhaul, non terrestrial network communication (NTN), mobile network, cooperative communication, coordinated multi-points (CoMP), interference mitigation, etc. are under development in the 5G communication system. In addition, in the 5G system, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC), which are an advanced coding modulation (ACM) scheme, and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA), which are an advanced connection technology, are under development.

[0006] Meanwhile, the Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving to the Internet of Things (IoT) where distributed components such as objects exchange information between each other. The Internet of Everything (IoE), which is a combination of the IoT technology and the big data processing technology through connection with a cloud server, has emerged as a new paradigm for the IoT. To implement the IoT, technology elements such as a sensing technology, wired / wireless communication and network infrastructure, service interface technology, and a security technology are required, and thus, a variety of technologies including a sensor network, machine-to-machine (M2M), and machine type communication (MTC) have been developed. In the IoT environment, a variety of technical factors can be provided to a connected object, and the connected object can automatically perceive / identify / analyze / reason / decide its situation, and can make a decision on a corresponding action. Based on a result of the decision, the connected object can actively change and control the network and can also perform a change / controlling of an external device. Therefore, the IoT can be applied to a variety of fields such as smart home, smart building / urban complex, smart car / vehicle, smart grid, health care, smart home appliance, security infrastructure, and an advanced medical service based on a combination of a variety of sensor networks, M2M, and MTC technologies.

[0007] Therefore, various attempts have been made to apply the 5G communication system to the IoT network. For example, technologies such as a sensor network, machine-to-machine (M2M), and machine type communication (MTC) are implemented by techniques such as beamforming, MIMO, and array antenna. The application of cloud RAN, which is the above-described big data processing technology, is an example of the convergence of the 5G technology and the IoT technology. In general, a mobile communication system is developed to provide a voice service while ensuring the activity of users.

[0008] Sidelink (SL) refers to a communication scheme in which a direct link is established between user equipments (UEs) and voice or data are exchanged directly among the UEs without intervention of a base station (BS). The SL is considered as a solution to alleviate a burden of a base station due to rapid increase of data traffic.

[0009] Vehicle-to-Everything (V2X) refers to a communication technique for exchanging information with other vehicles, pedestrians, and infrastructure constructed objects through wired / wireless communication. The V2X can be divided into four types such as Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I), Vehicle-to-Network (V2N), and Vehicle-to-Pedestrian (V2P). The V2X communication can be provided through a PC5 interface and / or a Uu interface.

[0010] As more and more communication devices require greater communication capacity, there is a demand for improved mobile broadband communication from legacy radio access technologies (RATs). Therefore, a communication system considering reliability and latency sensitive services or UEs is under discussion. The next generation radio access technology considering enhanced mobile broadband communication, massive MTC, ultra-reliable and low latency communication (URLLC), etc. can be referred to as New Radio Access Technology (RAT) or New Radio (NR). Even in NR, Vehicle-to-Everything (V2X) communication can be supported.

[0011] Meanwhile, in the case of SL communication related to a service with a high reliability requirement or a service with a relatively high reliability requirement, for example, a SL HARQ feedback operation and / or mechanism of a UE can be useful. SUMMARY

[0012] TECHNICAL PROBLEM

[0013] The present disclosure aims to provide a method for efficiently transmitting a signal in a wireless communication system and a device using the same. Specifically, the present disclosure aims to provide a channel access method for efficiently performing transmission in a wireless communication system and a device using the same.

[0014] TECHNICAL SOLUTION

[0015] In one aspect of the present disclosure, a user equipment (UE) used in a wireless communication system includes a communication module; and a processor that controls the communication module, wherein the processor is configured to determine a channel access priority class (CAPC) value for each SL transmission of a plurality of sidelink (SL) transmissions within a slot, and perform a Type 1 channel access procedure (CAP) based on a highest CAPC value among a plurality of CAPC values associated with the plurality of SL transmissions for transmitting the plurality of SL transmissions in the slot.

[0016] In another aspect of the disclosure, a method used by a user equipment (UE) in a wireless communication system is provided, including determining, for a plurality of sidelink (SL) transmissions within a slot, a channel access priority class (CAPC) value for each SL transmission, and performing a type 1 channel access procedure (CAP) based on a highest CAPC value among a plurality of CAPC values associated with the plurality of SL transmissions for transmitting the plurality of SL transmissions in the slot.

[0017] Preferably, the plurality of CAPC values can be associated with each contention window (CW) parameter, and the higher the CAPC value, the lower the channel access priority of the CW parameter.

[0018] Preferably, the plurality of SL transmissions can be transmitted to each respective receiving UE when the type 1 CAP is successful.

[0019] Preferably, the plurality of SL transmissions can correspond to two or more receiving UEs.

[0020] Preferably, the plurality of SL transmissions can be scheduled to be transmitted on a same time resource within the slot.

[0021] Preferably, the plurality of SL transmissions can be scheduled to be transmitted on different frequency resources within the slot.

[0022] Preferably, the plurality of SL transmissions can include a physical sidelink feedback channel (PSFCH) transmission.

[0023] Preferably, the plurality of SL transmissions can include a plurality of PSFCH transmissions.

[0024] Preferably, the CAPC value associated with the PSFCH transmission can be determined based on a traffic priority of a physical sidelink shared channel (PSSCH) corresponding to the PSFCH transmission.

[0025] Preferably, the traffic priority can be determined based on priority information within sidelink control information (SCI) scheduling the PSSCH.

[0026] Advantages of the Invention

[0027] The disclosure provides a method for efficiently transmitting a signal in a wireless communication system and a device using the same. In addition, the disclosure provides a channel access method for efficiently performing transmission in a wireless communication system and a device using the same.

[0028] Effects obtainable from the disclosure are not limited to the above-mentioned effects and other effects not mentioned above will become apparent to those skilled in the art from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 FIG. illustrates an example of a radio frame structure used in a wireless communication system;

[0030] Figure 2 FIG. illustrates an example of a downlink (DL) / uplink (UL) slot structure in a wireless communication system;

[0031] Figure 3 is a diagram for explaining a physical channel used in a 3GPP system and a typical signal transmission method using the same;

[0032] Figure 4 is a block diagram illustrating a configuration of a UE and a base station according to an embodiment of the present application;

[0033] Figures 5 to 12 FIG. illustrates an example of a sidelink (SL) communication procedure.

[0034] Figure 13 FIG. illustrates a configuration of a physical sidelink control channel / physical sidelink shared channel / physical sidelink feedback channel (PSCCH / PSSCH / PSFCH) in a slot.

[0035] Figure 14 FIG. illustrates a sidelink SSB (S-SSB) structure.

[0036] Figure 15 FIG. illustrates an example of a method performed by a sidelink UE to determine a PSFCH resource.

[0037] Figure 16 FIG. illustrates a new radio unlicensed (NR-U) service environment.

[0038] Figure 17 FIG. illustrates a communication method (e.g., wireless LAN) operating in an existing unlicensed band.

[0039] Figure 18 FIG. illustrates a category 4 LBT based channel access procedure.

[0040] Figure 19 FIG. illustrates an example of a channel occupancy time (COT) configuration and corresponding operation.

[0041] Figure 20 FIG. illustrates multiple SL transmissions.

[0042] Figures 21 to 22 FIG. illustrates a SL transmission method according to the present application. DETAILED DESCRIPTION

[0043] The terms used in the specification are adopted as general terms currently widely used in consideration of functions in the present application, but can be changed according to the intention, customs, and appearance of new technology of those skilled in the art. In addition, in a specific case, there are terms arbitrarily selected by the applicant, and in this case, the meaning thereof will be described in the corresponding description part of the present application. Therefore, it is intended that the terms used in the specification should not be analyzed only based on the name of the term, but should be analyzed based on the substantial meaning of the term and the context in the entire specification.

[0044] Throughout the specification and the subsequent claims, when it is described that one element is "connected" to another element, the one element can be "directly connected" to the other element or "electrically connected" to the other element through a third element. In addition, unless explicitly described to the contrary, the word "comprise" will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. Furthermore, in some example embodiments, a limitation such as "greater than or equal to" or "less than or equal to" based on a specific threshold value can be appropriately replaced with "greater than" or "less than", respectively.

[0045] The following techniques can be used in various wireless access systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier-FDMA (SC-FDMA), etc. The CDMA can be implemented by a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. The TDMA can be implemented by a radio technology such as global system for mobile communications (GSM) / general packet radio service (GPRS) / enhanced data rates for GSM evolution (EDGE). The OFDMA can be implemented by a radio technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, evolved UTRA (E-UTRA), etc. The UTRA is a part of a universal mobile telecommunication system (UMTS). A 3rd generation partnership project (3GPP) long term evolution (LTE) is a part of an evolved UMTS (E-UMTS) using evolved UMTS terrestrial radio access (E-UTRA), and LTE-advanced (A) is an evolved version of the 3GPP LTE. The 3GPP new radio (NR) is a system designed separately from the LTE / LTE-A, and is a system for supporting enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine type communication (mMTC) services as requirements of IMT-2020. For clarity, the 3GPP NR is mainly described, but the technical idea of the present application is not limited thereto.

[0046] 3GPP NR is described, but the technical idea of the present invention is not limited thereto.

[0047] Unless otherwise specified herein, a base station can include a next-generation node B (gNB) defined in 3GPP NR. Also, unless otherwise specified, a terminal can include a user equipment (UE). Hereinafter, to help understanding of the description, each content is described by embodiments respectively, but each embodiment can be used in combination with each other. In the present specification, the configuration of the UE can indicate the configuration by the base station. In more detail, the base station can configure the value of a parameter used in the operation of the UE or the wireless communication system by transmitting a channel or a signal to the UE.

[0048] Figure 1 An example of a radio frame structure used in a wireless communication system is illustrated.

[0049] Reference Figure 1 A radio frame (or radio frame) used in a 3GPP NR system can have a length of 10 ms (Δf max N f / 100)*T c ). Also, the radio frame includes 10 subframes (SFs) equal in size. Here, Δf max = 480*10 3 Hz, N f = 4096, T c = 1 / (Δf ref *N f,ref ), Δf ref = 15*10 3 Hz, and N f,ref = 2048. Numbers from 0 to 9 can be respectively assigned to the 10 subframes within one radio frame. The length of each subframe is 1 ms and can include one or more slots according to a subcarrier spacing. More specifically, in the 3GPP NR system, a subcarrier spacing that can be used is 15*2 μ kHz, and μ can have a value of μ = 0 ~ 4 as a subcarrier spacing configuration. That is, 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz can be used for the subcarrier spacing. One subframe having a length of 1 ms can include 2 μ slots. In this case, the length of each slot is 2 -μ ms. Numbers from 0 to 2 μ -1 can be respectively assigned to the 2 μ slots within one subframe. Also, numbers from 0 to 10*2 μThe numbers -1 are respectively assigned to a slot within a radio frame. Time resources can be distinguished by at least one of a radio frame number (also referred to as a radio frame index), a subframe number (also referred to as a subframe index), and a slot number (or slot index).

[0050] Figure 2 An example of a downlink (DL) / uplink (UL) slot structure in a wireless communication system is illustrated. In particular, Figure 2 The structure of a resource grid of a 3GPP NR system is shown.

[0051] There is one resource grid per antenna port. With reference to Figure 2 , a slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain and a plurality of resource blocks (RBs) in the frequency domain. One OFDM symbol also refers to one symbol interval. Unless otherwise specified, an OFDM symbol can be simply referred to as a symbol. One RB includes 12 consecutive subcarriers in the frequency domain. With reference to Figure 2 , a signal transmitted from each slot can be represented by a resource grid including N size,μ grid,x *N RB sc *subcarriers and N slot symb size,μ grid,x represents the number of resource blocks (RBs) according to subcarrier spacing component μ (x is DL or UL), and N slot symb represents the number of OFDM symbols in a slot. N RB sc is the number of subcarriers constituting one RB and N RB sc = 12. The OFDM symbol can be referred to as a cyclic shift OFDM (CP-OFDM) symbol or a discrete Fourier transform spread OFDM (DFT-s-OFDM) symbol according to a multiple access scheme.

[0052] The number of OFDM symbols included in one slot can vary according to the length of a cyclic prefix (CP). For example, one slot includes 14 OFDM symbols in the case of a normal CP, but one slot can include 12 OFDM symbols in the case of an extended CP. In a particular embodiment, the extended CP can be used only at 60 kHz subcarrier spacing. In Figure 2 , one slot is configured with 14 OFDM symbols as an example for convenience of description, but embodiments of the disclosure can be applied to a slot having a different number of OFDM symbols in a similar manner. With reference to​ Figure 2 Each OFDM symbol includes N size,μ grid,x *N RB sc subcarriers in the frequency domain. The types of subcarriers can be divided into data subcarriers for data transmission, reference signal subcarriers for transmission of reference signals, and guard bands. The carrier frequency is also referred to as the center frequency (fc).

[0053] One RB can be defined by N RB sc (e.g., 12) consecutive subcarriers in the frequency domain. For reference, a resource configured with one OFDM symbol and one subcarrier can be referred to as a resource element (RE) or a tone. Thus, one RB can be configured with N slot symb *N RB sc resource elements. Each resource element in the resource grid can be uniquely defined by a pair of indices (k, l) in one slot. k can be an index assigned from 0 to N size,μ grid,x *N RB sc -1 in the frequency domain, and l can be an index assigned from 0 to N slot symb -1 in the time domain.

[0054] For a UE to receive a signal from a base station or transmit a signal to a base station, the time / frequency of the UE can be synchronized with that of the base station. This is because when the base station and the UE are synchronized, the UE can determine the time and frequency parameters necessary to demodulate a DL signal at the right time and transmit a UL signal.

[0055] Each symbol of a radio frame used in time division duplex (TDD) or unpaired spectrum can be configured with at least one of a DL symbol, a UL symbol, and a flexible symbol. A radio frame used as a DL carrier in frequency division duplex (FDD) or paired spectrum can be configured with a DL symbol or a flexible symbol, and a radio frame used as a UL carrier can be configured with a UL symbol or a flexible symbol. In a DL symbol, DL transmission is possible, but UL transmission is not available. In a UL symbol, UL transmission is possible, but DL transmission is not available. The flexible symbol can be determined to be used as a DL or UL according to a signal.

[0056] Information on a type of each symbol, i.e., information indicating any one of a DL symbol, a UL symbol, and a flexible symbol, can be configured with a cell-specific or common radio resource control (RRC) signal. In addition, the information on the type of each symbol can be additionally configured with a UE-specific or dedicated RRC signal. The base station notifies i) a period of a cell-specific slot configuration, ii) a number of slots having only DL symbols from a beginning of the period of the cell-specific slot configuration, iii) a number of DL symbols from a first symbol of a slot immediately after the slot having only DL symbols, iv) a number of slots having only UL symbols from an end of the period of the cell-specific slot configuration, and v) a number of UL symbols from a last symbol of a slot immediately before the slot having only UL symbols, by using the cell-specific RRC signal. Here, a symbol not configured with any one of a UL symbol and a DL symbol is a flexible symbol.

[0057] When the information on the symbol type is configured with the UE-specific RRC signal, the base station can signal whether the flexible symbol is a DL symbol or a UL symbol with the cell-specific RRC signal. In this case, the UE-specific RRC signal cannot change the DL symbol or the UL symbol configured with the cell-specific RRC signal into another symbol type. The UE-specific RRC signal can signal a number of DL symbols among N slot symb symbols of a corresponding slot of each slot and a number of UL symbols among N slot symb symbols of the corresponding slot of each slot. In this case, the DL symbols of the slot can be continuously configured with the first symbol to the i-th symbol of the slot. In addition, the UL symbols of the slot can be continuously configured with the j-th symbol to the last symbol of the slot (where i < j). In the slot, a symbol not configured with any one of a UL symbol and a DL symbol is a flexible symbol.

[0058] The type of the symbol configured with the above RRC signal can be referred to as a semi-static DL / UL configuration. In the semi-static DL / UL configuration previously configured with the RRC signal, the flexible symbol can be indicated as a DL symbol, a UL symbol indication, or a flexible symbol by dynamic slot format information (SFI) transmitted on a physical DL control channel (PDCCH). In this case, the DL symbol or the UL symbol configured with the RRC signal is not changed to another symbol type. Table 1 illustrates the dynamic SFI that the base station can indicate to the UE.

[0059] Figure 3 is a diagram for explaining a physical channel used in a 3GPP system (e.g., NR) and a typical signal transmission method using the physical channel.

[0060] If the power of the UE is turned on or the UE camps in a new cell, the UE performs an initial cell search (S101). Specifically, the UE can synchronize with the BS in the initial cell search. To this end, the UE can receive a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) from the base station to synchronize with the base station and obtain information such as a cell ID. Thereafter, the UE can receive a physical broadcast channel from the base station and obtain broadcast information in the cell.

[0061] After the initial cell search is completed, the UE receives a physical downlink shared channel (PDSCH) according to a physical downlink control channel (PDCCH) and information in the PDCCH, so that the UE can obtain more specific system information than system information obtained through the initial cell search (S102). Here, the system information received by the UE is cell common system information for normal operation of the UE in a physical layer in a radio resource control (RRC), and is referred to as remaining system information, or referred to as system information block (SIB) 1.

[0062] When the UE initially accesses the base station or does not have a radio resource for signal transmission (i.e., the UE is in an RRC_IDLE mode), the UE can perform a random access procedure on the base station (operations S103 to S106). First, the UE can transmit a preamble through a physical random access channel (PRACH) (S103) and receive a response message for the preamble from the base station through a PDCCH and a corresponding PDSCH (S104). When the UE receives a valid random access response message, the UE transmits data including an identifier of the UE, etc. to the base station through a physical uplink shared channel (PUSCH) indicated by a UL grant transmitted from the base station through a PDCCH (S105). Next, the UE waits for reception of a PDCCH as an indication of the base station for collision resolution. If the UE successfully receives the PDCCH through the identifier of the UE (S106), the random access procedure is terminated. The UE can obtain UE-specific system information for normal operation of the UE in a physical layer in an RRC layer during the random access procedure. When the UE obtains the UE-specific system information, the UE enters an RRC connected mode (RRC_CONNECTED mode).

[0063] The RRC layer is used to generate or manage a message for controlling connection between the UE and a radio access network (RAN). In more detail, in the RRC layer, the base station and the UE can perform broadcasting of cell system information required for each UE in the cell, management of mobility and handover, measurement reporting of the UE, storage management including UE capability management and device management. In general, because an update period of a signal delivered in the RRC layer is longer than a transmission time interval (TTI) in a physical layer, an RRC signal is not changed and maintained for a relatively long interval.

[0064] After the above-described procedure, the UE receives a PDCCH / PDSCH (S107) and transmits a physical uplink shared channel (PUSCH) / physical uplink control channel (PUCCH) (S108) as a general UL / DL signal transmission procedure. In particular, the UE can receive downlink control information (DCI) through the PDCCH. The DCI can include control information such as resource allocation information for the UE. In addition, the format of the DCI can vary according to a predetermined use. The uplink control information (UCI) transmitted by the UE to the base station through the UL includes a DL / UL ACK / NACK signal, a channel quality indicator (CQI), a precoding matrix index (PMI), a rank indicator (RI), etc. Here, the CQI, the PMI, and the RI can be included in channel state information (CSI). In the 3GPP NR system, the UE can transmit control information such as the HARQ-ACK and the CSI described above through the PUSCH and / or the PUCCH.

[0065] Figure 4 is a block diagram illustrating a configuration of a UE and a base station according to an embodiment of the present application. In an embodiment of the present application, the UE can be implemented with various types of wireless communication devices or computing devices that guarantee portability as well as mobility. The UE can be referred to as a user equipment (UE), a station (STA), a mobile subscriber (MS), etc. Further, in an embodiment of the present application, the base station controls and manages a cell (e.g., a macro cell, a femto cell, a pico cell, etc.) corresponding to a service area, and performs functions of signal transmission, channel designation, channel monitoring, self-diagnosis, relaying, etc. The base station can be referred to as a next-generation node B (gNB) or an access point (AP).

[0066] As illustrated in the drawings, the UE 100 according to an embodiment of the present disclosure can include a processor 110, a communication module 120, a memory 130, a user interface 140, and a display unit 150.

[0067] First, the processor 110 can execute various instructions or programs within the UE 100 and process data. Further, the processor 110 can control the entire operation of each unit including the UE 100, and can control transmission / reception of data between the units. Here, the processor 110 can be configured to perform operations according to the embodiments described in the present application. For example, the processor 110 can receive slot configuration information, determine a slot configuration based on the slot configuration information, and perform communication according to the determined slot configuration.

[0068] Next, the communication module 120 can be an integrated module that performs wireless communication using a wireless communication network and performs wireless LAN access using a wireless LAN. To this end, the communication module 120 is capable of including a plurality of network interface cards (NICs), such as cellular communication interface cards 121 and 122 and an unlicensed band communication interface card 123, in an internal or external form. In the drawing, the communication module 120 is shown as an integrated module as a whole, but unlike the drawing, each network interface card can be independently arranged according to a circuit configuration or usage.

[0069] The cellular communication interface card 121 can transmit or receive radio signals with at least one of the base station 200, an external device, and a server by using a mobile communication network and provide a cellular communication service in a first frequency band based on an instruction from the processor 110. According to an embodiment, the cellular communication interface card 121 can include at least one NIC module that uses a frequency band less than 6 GHz. The at least one NIC module of the cellular communication interface card 121 can independently perform cellular communication with at least one of the base station 200, the external device, and the server according to a cellular communication standard or protocol in a sub-6 GHz band supported by the corresponding NIC module.

[0070] The cellular communication interface card 122 can transmit or receive radio signals with at least one of the base station 200, an external device, and a server by using a mobile communication network and provide a cellular communication service in a second frequency band based on an instruction from the processor 110. According to an embodiment, the cellular communication interface card 122 can include at least one NIC module that uses a frequency band greater than 6 GHz. The at least one NIC module of the cellular communication interface card 122 can independently perform cellular communication with at least one of the base station 200, the external device, and the server according to a cellular communication standard or protocol in a super-6 GHz band supported by the corresponding NIC module.

[0071] The unlicensed band communication interface card 123 transmits or receives radio signals with at least one of the base station 200, an external device, and a server by using a third frequency band that is an unlicensed band and provides an unlicensed band communication service based on an instruction from the processor 110. The unlicensed band communication interface card 123 can include at least one NIC module that uses an unlicensed band. For example, the unlicensed band can be a frequency band of 2.4 GHz, 5 GHz, 6 GHz, 7 GHz, or 52.6 GHz or more. The at least one NIC module of the unlicensed band communication interface card 123 can independently or non-independently perform wireless communication with at least one of the base station 200, the external device, and the server according to an unlicensed band communication standard or protocol of the frequency band supported by the corresponding NIC module.

[0072] The memory 130 stores control programs used in the UE 100 and various data thereof. Such control programs can include prescribed programs needed to perform wireless communication with at least one of the base station 200, external devices, and servers.

[0073] Next, the user interface 140 includes various input / output means provided in the UE 100. In other words, the user interface 140 can receive user input using various input means, and the processor 110 can control the UE 100 based on the received user input. Also, the user interface 140 can perform output based on instructions from the processor 110 using various output means.

[0074] Next, the display unit 150 outputs various images on a display screen. The display unit 150 can output various display objects such as content or a user interface executed by the processor 110 based on control instructions from the processor 110.

[0075] Also, the base station 200 according to an embodiment of the present application can include a processor 210, a communication module 220, and a memory 230.

[0076] First, the processor 210 can execute various instructions or programs and process internal data of the base station 200. Also, the processor 210 can control the overall operation of each unit in the base station 200 and control transmission and reception of data between the units. Here, the processor 210 can be configured to perform operations according to the embodiments described in the present application. For example, the processor 210 can signal a slot configuration and perform communication according to the signaled slot configuration.

[0077] Next, the communication module 220 can be an integrated module that performs wireless communication using a wireless communication network and performs wireless LAN access using a wireless LAN. To this end, the communication module 220 can include a plurality of network interface cards, such as cellular communication interface cards 221 and 222 and an unlicensed band communication interface card 223, in an internal or external form. In the drawing, the communication module 220 is shown as an integrated module as a whole, but each network interface card can be independently arranged according to a circuit configuration or usage, unlike the drawing.

[0078] The cellular communication interface card 221 can transmit or receive a radio signal with at least one of the UE 100, the external device, and the server by using a mobile communication network and provide a cellular communication service in a first frequency band based on an instruction from the processor 210. According to an embodiment, the cellular communication interface card 221 can include at least one NIC module using a frequency band less than 6 GHz. The at least one NIC module of the cellular communication interface card 221 can independently perform cellular communication with at least one of the UE 100, the external device, and the server according to a cellular communication standard or protocol in a frequency band less than 6 GHz supported by the corresponding NIC module.

[0079] The cellular communication interface card 222 can transmit or receive a radio signal with at least one of the UE 100, the external device, and the server by using a mobile communication network and provide a cellular communication service in a second frequency band based on an instruction from the processor 210. According to an embodiment, the cellular communication interface card 222 can include at least one NIC module using a frequency band of 6 GHz or more. The at least one NIC module of the cellular communication interface card 222 can independently perform cellular communication with at least one of the UE 100, the external device, and the server according to a cellular communication standard or protocol in a frequency band of 6 GHz or more supported by the corresponding NIC module.

[0080] The unlicensed band communication interface card 223 transmits or receives a radio signal with at least one of the UE 100, the external device, and the server by using a third frequency band that is an unlicensed band and provides an unlicensed band communication service based on an instruction from the processor 210. The unlicensed band communication interface card 223 can include at least one NIC module using an unlicensed band. For example, the unlicensed band can be a frequency band of 2.4 GHz, 5 GHz, 6 GHz, 7 GHz, or 52.6 GHz or more. The at least one NIC module of the unlicensed band communication interface card 223 can independently or dependently perform wireless communication with at least one of the UE 100, the external device, and the server according to an unlicensed band communication standard or protocol of the frequency band supported by the corresponding NIC module.

[0081] Figure 4 FIG. 1 is a block diagram illustrating a UE 100 and a base station 200 according to an embodiment of the present application, and the separately illustrated blocks are logically divided elements of the devices. Accordingly, the aforementioned elements of the devices can be mounted in a single chip or a plurality of chips according to the design of the devices. Also, a part of the configuration of the UE 100, e.g., the user interface 140, the display unit 150, etc., can be selectively provided in the UE 100. Also, the user interface 140, the display unit 150, etc. can be additionally provided in the base station 200 if necessary.

[0082] <sidelink (SL) communication>

[0083] SL communication refers to a communication method that enables a UE to establish a direct link and directly exchange voice or data without passing through a base station. In SL communication, Figure 14 a base station can be replaced by a UE. SL communication can be interchanged with vehicle-to-everything (V2X) communication.

[0084] Figure 5 An example of a UE and a base station for performing V2X or SL communication is illustrated.

[0085] Referring to Figure 5 In V2X / SL communication, the term "UE" can primarily refer to a UE of a user. However, when a network device such as a base station transmits and receives a signal according to a communication method between UEs, the base station can also be considered as a type of UE.

[0086] The UE 1 can select a resource unit corresponding to a specific resource from a resource pool that is a set of resources, and can operate by using the resource unit to transmit an SL signal. The UE 2 that is a reception UE can receive a configuration of a resource pool used for the UE 1 to transmit a signal, and can detect a signal of the UE 1 from the resource pool.

[0087] Here, when the UE 1 is within a connection range of a base station, the base station can report the resource pool. However, when the UE 1 is outside the connection range of the base station, another UE can report the resource pool, or the resource pool can be determined as a predetermined resource.

[0088] Figure 6 An example of a resource unit for V2X or SL communication is illustrated.

[0089] Referring to Figure 6 A resource pool can include a plurality of resource units, and each UE can select and use one resource unit or a plurality of resource units to transmit an SL signal. All frequency resources of a resource pool can be divided into N F units, and all time resources of the resource pool can be divided into N T units. Accordingly, a total of N F *N T resource units can be defined in a resource pool.

[0090] As Figure 6 indicated in the above, one resource unit (e.g., unit #0) can be periodically repeated. Alternatively, in order to obtain a diversity effect in a time or frequency dimension, an index of a physical resource unit to which one logical resource unit is mapped can vary in a predetermined pattern over time. In this structure of a resource unit, a resource pool can refer to a set of resource units that a UE that wants to transmit an SL signal can use for transmission.

[0091] Resource pools can be classified into multiple types. For example, according to the contents of SL signals transmitted in each resource pool, the resource pools can be classified as follows.

[0092] (1) A scheduling assignment (SA) can be a signal including information such as a location of a resource for a transmitting UE to transmit a SL data channel, a modulation and coding scheme (MCS) or a multiple input multiple output (MIMO) transmission method required for demodulating other data channels, and a timing advance (TA). The SA can also be multiplexed and transmitted on the same resource unit as the SL data, in which case the SA resource pool can refer to a resource pool in which the SA is multiplexed and transmitted with the SL data. The SA can also be referred to as a SL control channel.

[0093] (2) A SL data channel (physical sidelink shared channel: PSSCH) can be a resource pool used by a transmitting UE to transmit user data. If the SA is multiplexed and transmitted on the same resource unit as the SL data, only the SL data channel excluding the SA information can be transmitted in the resource pool of the SL data channel. That is, a resource element (RE) used to transmit the SA information on a single resource unit within the SA resource pool can still be used to transmit the SL data in the resource pool for the SL data channel.

[0094] Hereinafter, resource allocation in a SL will be described.

[0095] Figure 7 An example of a procedure in which a UE performs V2X or SL communication according to a transmission mode will be described.

[0096] Referring to Figure 7 , Figure 7 (a) of FIG. 1 illustrates UE operations related to transmission mode 1 or transmission mode 3, and Figure 7 (b) of FIG. 1 illustrates UE operations related to transmission mode 2 or transmission mode 4.

[0097] Referring to Figure 7 (a), in transmission mode 1 / 3, a base station performs resource scheduling for a UE 1 through a PDCCH (more specifically, a downlink control information (DCI)), and the UE 1 performs SL / VTX communication with a UE 2 according to the resource scheduling. The UE 1 can transmit sidelink control information (SCI) to the UE 2 through a physical sidelink control channel (PSCCH), and then transmit data based on the SCI through a physical sidelink shared channel (PSSCH). In LTE SL, transmission mode 1 can be applied to general SL communication, and transmission mode 3 can be applied to V2X SL communication.

[0098] Referring to Figure 7(b), in transmission mode 2 / 4, a UE can autonomously schedule resources. More specifically, in LTE SL, transmission mode 2 can be applied to general SL communication, in which a UE can perform SL operation by autonomously selecting resources from a configured resource pool. Transmission mode 4 can be applied to V2X SL communication, in which a UE can autonomously select resources within a selection window via a sensing / SA decoding procedure, and then perform V2X SL operation. UE 1 can transmit SCI to UE 2 through PSCCH, and then transmit data based on the SCI through PSSCH. In the following, transmission mode can be abbreviated as mode. Procedures related to sensing and resource (re)selection can be supported in resource allocation mode 2. A sensing procedure can be defined as decoding SCI from another UE and / or SL measurement. Decoding SCI in a sensing procedure can provide at least information about SL resources indicated by a UE transmitting the SCI. When the SCI is decoded, the sensing procedure can use L1 SL reference signal received power (RSRP) measurement based on SL demodulation reference signal (DMRS). A resource (re)selection procedure can use the result of the sensing procedure to determine resources for SL transmission.

[0099] Figure 8 An example of a method of illustrating a UE selecting a transmission resource for transmitting a signal is shown.

[0100] Reference Figure 8 A UE can identify transmission resources reserved by other UEs or resources being used by other UEs by sensing within a sensing window, and can randomly select a resource with less interference from remaining resources excluding the reserved or used resources within a selection window.

[0101] For example, a UE can decode PSCCH including information about a period of reserved resources within a sensing window, and can measure PSSCH RSRP of resources determined periodically based on the PSCCH. The UE can exclude resources having a PSSCH RSRP value exceeding a threshold from a selection window. Subsequently, the UE can randomly select a SL resource from among remaining resources within the selection window.

[0102] Figure 9 An example of three cast types of NR sidelink is shown.

[0103] Reference Figure 9 NR sidelink supports three types of cast: unicast, groupcast, and broadcast. In unicast SL communication, a UE can communicate one-to-one with another UE. In groupcast SL communication, a UE can perform SL communication with one or more UEs in a group to which the UE belongs. Groupcast SL communication can be replaced with SL multicast communication, SL one-to-many communication, etc.

[0104] In the following, a hybrid automatic repeat request (HARQ) procedure in the SL is described.

[0105] In SL unicast and groupcast, HARQ feedback and HARQ combining in the physical layer can be supported. For example, when a receiving UE operates in resource allocation mode 1 or 2, the receiving UE can receive a PSSCH from a transmitting UE and can transmit HARQ feedback on the PSSCH to the transmitting UE through a physical sidelink feedback channel (PSFCH) by using a sidelink feedback control information (SFCI) format.

[0106] For example, SL HARQ feedback can be enabled for groupcast. That is, in non-CBG operation, two HARQ feedback options can be supported for groupcast.

[0107] (1) Groupcast Option 1: After a receiving UE decodes a PSCCH targeting the receiving UE, the receiving UE can transmit a HARQ-NACK to a transmitting UE through a PSFCH when the receiving UE fails to decode a transport block related to the PSCCH. However, the receiving UE can not transmit a HARQ-ACK to the transmitting UE when the receiving UE decodes the PSCCH targeting the receiving UE and successfully decodes the transport block related to the PSCCH.

[0108] (2) Groupcast Option 2: After a receiving UE decodes a PSCCH targeting the receiving UE, the receiving UE can transmit a HARQ-NACK to a transmitting UE through a PSFCH when the receiving UE fails to decode a transport block related to the PSCCH. The receiving UE can transmit a HARQ-ACK to the transmitting UE through the PSFCH when the receiving UE decodes the PSCCH targeting the receiving UE and successfully decodes the transport block related to the PSCCH.

[0109] For example, in SL communication related to a service with a requirement of high reliability or a service with a requirement of relatively high reliability, a SL HARQ feedback operation and / or mechanism of a UE can be useful. For example, in SL communication related to a service with a requirement of high reliability, an operation in which a UE receiving the service transmits a SL HARQ feedback to a UE transmitting the service can help to meet the requirement of high reliability.

[0110] A HARQ feedback resource can include a HARQ feedback transmission resource and / or a HARQ feedback reception resource. For example, a HARQ feedback transmission resource can include a resource for transmitting a HARQ feedback and / or a resource related to a transmission of a HARQ feedback. For example, a HARQ feedback reception resource can include a resource for receiving a HARQ feedback and / or a resource related to a reception of a HARQ feedback.

[0111] A PSSCH resource can include a PSSCH transmission resource and / or a PSSCH reception resource. For example, a PSSCH transmission resource can include a resource for transmitting a PSSCH and / or a resource related to a transmission of a PSSCH. For example, a PSSCH reception resource can include a resource for receiving a PSSCH and / or a resource related to a reception of a PSSCH.

[0112] A PSCCH resource can include a PSCCH transmission resource and / or a PSSCH reception resource. For example, a PSCCH transmission resource can include a resource for transmitting a PSCCH and / or a resource related to a transmission of a PSCCH. For example, a PSCCH reception resource can include a resource for receiving a PSCCH and / or a resource related to a reception of a PSCCH.

[0113] A resource can include at least one of a time domain resource, a frequency domain resource, and / or a code domain resource.

[0114] When a resource collision occurs in at least one of a PSSCH transmission, a PSCCH transmission, and / or a HARQ feedback transmission of a UE, a SL HARQ feedback procedure and / or operation of the UE can be difficult to operate correctly. For example, when a resource collision occurs in at least one of a PSSCH transmission, a PSCCH transmission, and / or a HARQ feedback transmission of a UE, an overall SL HARQ feedback procedure and / or operation of the UE can be difficult to perform accurately.

[0115] When a receiving UE successfully receives a PSSCH but an error occurs in a HARQ feedback (e.g., a HARQ ACK) due to a resource collision, a transmitting UE can unnecessarily retransmit the PSSCH to the receiving UE. For example, when a receiving UE fails to receive a PSSCH and does not deliver a HARQ feedback to a transmitting UE due to a resource collision, reliability or performance related to a SL communication can be degraded. For example, when a receiving UE fails to receive a PSCCH and / or a PSSCH transmitted from a transmitting UE and a HARQ NACK corresponding to the PSCCH or the PSSCH is not correctly delivered to the transmitting UE due to a resource collision, reliability or performance related to a SL communication can be degraded. Accordingly, there is a need to determine a HARQ feedback resource to avoid or minimize a collision between multiple UEs.

[0116] A transmitting UE can transmit a PSCCH and / or a PSSCH to a receiving UE. For example, the transmitting UE can transmit SL information to the receiving UE by using a PSCCH resource and / or a PSSCH resource. For example, the SL information can include at least one of SL control information, SL data, a SL packet, a SL transport block (TB), a SL message, and / or a SL service.

[0117] The receiving UE can determine the HARQ feedback resource. Also, for example, the transmitting UE can determine the HARQ feedback resource.

[0118] The HARQ feedback resource can be configured to have an association or linkage with the PSSCH. For example, the HARQ feedback resource can include at least one of a time domain resource, a frequency domain resource, and / or a code domain resource. For example, a location of the HARQ feedback resource can be configured to have an association or linkage with an associated PSSCH resource. For example, the location of the HARQ feedback resource can be configured to have an association or linkage with a location of the associated PSSCH resource based on a predefined function. For example, the HARQ feedback resource can be determined based on at least one of information about a time domain related to the PSSCH, information about a frequency domain related to the PSSCH, and / or information about a code domain related to the PSSCH.

[0119] Additionally / alternatively, for example, the HARQ feedback resource can be configured to have an association or linkage with the PSCCH. For example, a location of the HARQ feedback resource can be configured to have an association or linkage with an associated PSCCH resource. For example, the location of the HARQ feedback resource can be configured to have an association or linkage with a location of the associated PSCCH resource based on a predefined function. For example, the HARQ feedback resource can be determined based on at least one of information about a time domain related to the PSCCH, information about a frequency domain related to the PSCCH, and / or information about a code domain related to the PSCCH.

[0120] The HARQ feedback resource can be configured in the form of a subset of frequency resources used for the PSSCH transmission and / or the PSCCH transmission. For example, a frequency domain of the HARQ feedback resource can be configured in the form of a subset of a frequency domain of the associated PSSCH resource and / or the PSCCH resource. For example, the frequency domain of the HARQ feedback resource can be included in the frequency domain of the PSSCH resource and / or the PSCCH resource.

[0121] Figure 10 An example of a resource for transmitting HARQ feedback in NR sidelink is illustrated.

[0122] Referring to Figure 10 The transmitting UE can transmit the PSCCH and / or the PSSCH to the receiving UE through four sub-channels. In this case, a frequency domain of the HARQ feedback resource related to the PSCCH and / or the PSSCH can be a subset of frequency resources used by the transmitting UE to transmit the PSCCH or the PSSCH.

[0123] A time gap can be configured between the HARQ feedback resource and the PSSCH resource. Additionally / alternatively, for example, a time gap can be configured between the HARQ feedback resource and the PSCCH resource. For example, a time gap can be configured between a time when the receiving UE receives the PSSCH and / or the PSCCH and a time when the receiving UE transmits the HARQ feedback, taking into account the decoding capability and / or the latency requirement of the UE (e.g., V2X message and / or service related latency requirement). For example, a time gap can be configured between a time when the transmitting UE receives the HARQ feedback and a time when the transmitting UE (re)transmits the PSSCH and / or the PSCCH, taking into account the decoding capability and / or the latency requirement of the UE.

[0124] The time gap can be configured commonly within the resource pool. For example, the time gap can be configured commonly between different UEs within the resource pool. For example, the time gap can be configured commonly for the transmitting UE and the receiving UE. Thus, the UE can simply determine the HARQ feedback resource. For example, the time gap can be configured as specific to the resource pool.

[0125] The time gap can be configured or specified to be less than and / or equal to a minimum among latency budgets of coexisting services on the resource pool. For example, when service A and service B coexist on the resource pool and the latency budget of service A is less than the latency budget of service B, the time gap can be configured or specified to be less than or equal to the latency budget of service A.

[0126] The time gap can be specified such that the number of maximum retransmissions related to a transport block (TB) configured specifically to the resource pool, a type of the service, a priority of the service, a type of the broadcast, and / or a QoS requirement of the service is (fully) supported / performed within a latency budget for the (related) service on the resource pool. For example, the number of maximum retransmissions can be a maximum number of allowable retransmissions including an initial transmission.

[0127] The time gap can be configured or designated to be greater than and / or equal to a maximum among decoding capabilities of the UEs. For example, the decoding capability can be a processing time of the UE required from a time when the UE terminates / receives the PSSCH to a time when the UE starts transmitting the PSFCH. Also / alternatively, for example, the decoding capability can be a processing time of the UE required from a time when the UE terminates / receives the PSCCH to a time when the UE starts transmitting the PSFCH. For example, the time gap can be configured or designated to be greater than and / or equal to a maximum among decoding capabilities of the UEs in the resource pool. For example, when UEs A, B, and C perform SL communication in the resource pool and the decoding capability of the UE A is the lowest, the time gap can be configured or designated to be a value greater than or equal to a processing time required from a time when the UE terminates / receives the PSSCH and / or PSCCH of the UE A to a time when the UE A starts transmitting the PSFCH.

[0128] The time gap can be differently or independently configured according to a type of the service, a priority of the service, a type of the SL communication, a session related to the service, a PPPP related to the service, a PPPR related to the service, a target block error rate (BLER) related to the service, a target signal to interference plus noise ratio (SINR) related to the service, a delay budget related to the service, and / or a UE capability. For example, the time gap can be differently or independently configured according to a type of the service, a priority of the service, a type of the SL communication, a session related to the service, a PPPP related to the service, a PPPR related to the service, a target block error rate (BLER) related to the service, a target signal to interference plus noise ratio (SINR) related to the service, a delay budget related to the service, and / or a UE capability within the resource pool. For example, the type of the SL communication can include at least one of unicast, groupcast, and / or broadcast.

[0129] The receiving UE can transmit the HARQ feedback to the transmitting UE. For example, the receiving UE can transmit the HARQ feedback corresponding to the PSCCH and / or the PSSCH to the transmitting UE. For example, the receiving UE can transmit the HARQ feedback to the transmitting UE by using the HARQ feedback resource determined based on the PSCCH resource and / or the PSSCH resource. For example, the transmitting UE can receive the HARQ feedback from the receiving UE on the HARQ feedback resource determined based on the PSCCH resource and / or the PSSCH resource.

[0130] The HARQ feedback can be a HARQ ACK when the receiving UE successfully receives the PSCCH and / or the PSSCH. For example, the HARQ feedback can be at least one of a HARQ NACK and / or a discontinuous detection (DTX) when the receiving UE fails to receive the PSCCH and / or the PSSCH.

[0131] In groupcast where multiple UEs in a group perform SL communication with each other, HARQ feedback resources can be configured in two forms.

[0132] (1) Option A: Common HARQ feedback resources can be configured for receiving UEs. For example, when a transmitting UE transmits PSSCH and / or PSCCH to multiple receiving UEs, HARQ feedback resources can be commonly configured for the multiple receiving UEs that have received the PSSCH and / or PSCCH.

[0133] (2) Option B: Different or independent HARQ feedback resources can be configured for receiving UEs. For example, different or independent HARQ feedback resources can be configured for each receiving UE or for each subgroup including one or more receiving UEs. For example, when a transmitting UE transmits PSSCH and / or PSCCH to multiple receiving UEs, different or independent HARQ feedback resources can be respectively configured for the multiple receiving UEs or for multiple subgroups that have received the PSSCH and / or PSCCH.

[0134] Option A can be applicable only to groupcast option 1. For example, in groupcast option 1, only when PSCCH and / or PSSCH is failed to be received, multiple receiving UEs can transmit HARQ NACK to the transmitting UE by using HARQ feedback resources commonly configured for the multiple receiving users. For example, HARQ NACK can be configured in the form of a single frequency network (SFN). In this case, the transmitting UE can not individually receive HARQ NACK transmitted by the multiple receiving UEs. Therefore, the transmitting UE can not know which receiving UE has transmitted HARQ NACK. However, the transmitting UE can know that at least one of the multiple receiving UEs has transmitted HARQ NACK, and can retransmit PSCCH and / or PSSCH to the multiple receiving UEs.

[0135] In Option A, unicast-related HARQ feedback resource structures can be reused. In addition / alternatively, for example, in Option A, overhead related to HARQ feedback resources can be reduced. However, in Option A, there can be a limitation that the transmitting UE cannot determine / identify DTX. For example, when the transmitting UE transmits PSSCH and / or PSCCH to a receiving UE, the receiving UE can fail to receive PSCCH scheduling PSSCH. In this case, according to Option A, the receiving UE can not transmit HARQ NACK to the transmitting UE. Therefore, the transmitting UE can misinterpret that the receiving UE has successfully received PSSCH.

[0136] In Option B, different or independent HARQ feedback resources can be allocated to each receiving UE or each subgroup in a group including multiple receiving UEs. Here, for example, according to Option B, as the number of receiving UEs or subgroups included in the group increases, a larger number of HARQ feedback resources can be needed. For example, for a group including N receiving UEs, N-1 HARQ feedback resources can be needed. For example, Option B can be limited to groupcast Option 2.

[0137] Figure 11 An example of a process for transmitting and receiving HARQ feedback on PSCCH and / or PSSCH is illustrated.

[0138] Referring to Figure 11 The multiple receiving UEs can each transmit HARQ feedback to the transmitting UE. For example, the multiple receiving UEs can each transmit HARQ feedback corresponding to the PSCCH and / or PSSCH to the transmitting UE. The multiple receiving UEs can each transmit the HARQ feedback to the transmitting UE by using HARQ feedback resources determined based on the PSCCH resources and / or the PSSCH resources.

[0139] When the receiving UE successfully receives the PSCCH and / or the PSSCH, the HARQ feedback can be a HARQ ACK. For example, when the receiving UE fails to receive the PSCCH and / or the PSSCH, the HARQ feedback can be at least one of a HARQ NACK and / or a discontinuous detection (DTX).

[0140] The UE can determine the HARQ feedback transmission power based on at least one of a SL path loss value derived / obtained based on a reference signal on a SL channel, a SL RSRP value derived / obtained based on a reference signal on a SL channel, a SL RSRQ value derived / obtained based on a reference signal on a SL channel, an open loop power control parameter, and / or a closed loop power control parameter. For example, when the transmitting UE transmits a reference signal to the receiving UE through a SL channel, the receiving UE can determine the HARQ feedback transmission power based on at least one of a SL path loss value derived / obtained based on a reference signal on a SL channel, a SL RSRP value derived / obtained based on a reference signal on a SL channel, a SL RSRQ value derived / obtained based on a reference signal on a SL channel, an open loop power control parameter, and / or a closed loop power control parameter.

[0141] The reference signal on the SL channel can be predefined. The reference signal on the SL channel can be a DMRS transmitted on the PSSCH (i.e., PSSCH DMRS) or a DMDS transmitted on the PSCCH (i.e., PSCCH DMRS). The reference signal on the SL channel can be a CSI-RS transmitted on the PSSCH. The reference signal on the SL channel can be a reference signal for estimating a quality of the SL channel (e.g., CQI, PMI, or RI). For example, the reference signal on the SL channel can be a reference signal for measuring at least one of a SL path loss value, a SL RSRP value, and / or a SL RSRQ value.

[0142] The SL path loss can be a path loss in a link between the transmitting UE and the receiving UE. For example, the open loop power control parameter and / or the closed loop power control parameter can be preconfigured. For example, the open loop power control parameter can include a Po and / or an alpha value.

[0143] The Po can be a power control parameter for averaging satisfying a target error rate (e.g., a block error rate (BLER) or a frame error rate (FER)) related to a packet / message transmission. Additionally / alternatively, for example, the Po can be a power control parameter related to an average received SINR between the transmitting UE and the receiving UE. For example, the Po can be a UE-specific power control parameter, a resource pool, a type of a service, a priority of a service, a QoS requirement related to a service, a size of a (frequency) resource for a SL transmission, a MCS value for a SL transmission, a congestion level (e.g., CBR) related to a resource pool, and / or a type of a broadcast. For example, when calculating / deriving a HARQ feedback transmission power based on a SL RSRP and / or a SL RSRQ value / range, a different Po value / range can be mapped / configured for each (preconfigured) SL RSRP or SL RSIQ value / range.

[0144] When the HARQ feedback transmission power is derived / computed based on the SL path loss, the alpha value can be a weight applied to the (measured) path loss compensation. In addition / alternatively, when the HARQ feedback transmission power is computed / derived based on the SL RSRP and / or SL RSRQ value / range, the alpha value can be a weight applied to the (measured) SL RSRP or SL RSRQ value / range. In addition / alternatively, when the HARQ feedback transmission power is computed / derived based on the SL RSRP and / or SL RSRQ value / range, the alpha value can be a weight applied to the HARQ feedback transmission power mapped / configured for each (measured) SL RSRP or SL RSIQ value / range. Here, the alpha value / range can be configured to be specific to the UE, the resource pool, the type of service, the priority of service, the QoS requirement related to the service, the size of the (frequency) resource used for the SL transmission, the MCS value used for the SL transmission, the congestion level (e.g., CBR) related to the resource pool, and / or the type of broadcast. Different alpha values / ranges can be mapped / configured for each (preconfigured) SL RSRP or SL RSRQ value / range when the HARQ feedback transmission power is computed / derived based on the SL RSRP and / or SL RSRQ value / range.

[0145] When the HARQ feedback transmission power is computed / derived based on the SL RSRP and / or SL RSRQ value / range, different offset values / ranges can be mapped / configured for each (preconfigured) SL RSRP or SL RSIQ value / range. The UE measuring the SL RSRP and / or SL RSRQ can apply the offset related to the SL RSRP value and / or SL RSRQ value to the (preconfigured normalized or nominal) SL (HARQ feedback) (maximum) transmission power, thereby determining the final HARQ feedback transmission power. Here, for example, the offset value / range can be configured to be specific to the UE, the resource pool, the type of service, the priority of service, the QoS requirement related to the service, the size of the (frequency) resource used for the SL transmission, the MCS value used for the SL transmission, the congestion level (e.g., CBR) related to the resource pool, and / or the type of broadcast.

[0146] Different (normalized or nominal) (maximum) HARQ feedback transmission power values / ranges can be mapped / configured for each SL RSRP and / or SL RSRQ value / range. For example, the (normalized or nominal) (maximum) HARQ feedback transmission power values / ranges can be configured to be specific to the UE, the resource pool, the type of service, the priority of service, the QoS requirement related to the service, the size of the (frequency) resource used for the SL transmission, the MCS value used for the SL transmission, the congestion level (e.g., CBR) related to the resource pool, and / or the type of broadcast.

[0147] The transmission power value related to the reference signal and / or the SL channel including the reference signal can be signaled to the UE via a predefined channel. The transmitting UE can transmit the transmission power value related to the reference signal and / or the SL channel including the reference signal to the receiving UE via a predefined channel. The predefined channel can be the PSCCH. The receiving UE can be a terminal that measures at least one of the SL path loss, the SL RSRP, and / or the SL RSRQ based on the reference signal.

[0148] The open loop power control parameters (and / or the (maximum or minimum) HARQ feedback transmission power value mapped / configured for each SL RSRP (and / or SL RSRQ) value / range) can be configured differently or independently according to the type of service, the priority of the service, the type of SL communication (e.g., unicast, groupcast, or broadcast), the congestion level (e.g., channel busy ratio (CBR)) related to the resource pool, the session related to the service, the PPPP related to the service, the PPRR related to the service, the target block error rate (BLER) related to the service, the target signal to interference plus noise ratio (SINR) related to the service, the (minimum or maximum) target communication distance related to the service, and / or the delay budget related to the service. In addition / alternatively, for example, the closed loop power control operation / parameters can be managed / configured differently or independently according to the type of service, the priority of the service, the type of SL communication (e.g., unicast, groupcast, or broadcast), the congestion level (e.g., CBR) related to the resource pool, the session related to the service, the PPPP related to the service, the PPRR related to the service, the target block error rate (BLER) related to the service, the target signal to interference plus noise ratio (SINR) related to the service, the (minimum or maximum) target communication distance related to the service, and / or the delay budget related to the service.

[0149] The open loop power control parameters related to the HARQ feedback can be configured differently or independently from the open loop power control parameters related to the PSSCH and / or PSCCH. In addition / alternatively, the closed loop power control operation / parameters related to the HARQ feedback can be managed / configured differently or independently from the closed loop power control operation / parameters related to the PSSCH and / or PSCCH.

[0150] FDM of HARQ feedback resources can be allowed or configured only for receiving UEs whose distance to the transmitting UE receiving the HARQ feedback is within a pre-set threshold. Additionally / alternatively, FDM of HARQ feedback resources can be allowed or configured only for receiving UEs whose SL pathloss difference in the link between the transmitting UE and the receiving UE is within a pre-set threshold. Additionally / alternatively, FDM of HARQ feedback resources can be allowed or configured only for receiving UEs whose SL RSRP difference in the link between the transmitting UE and the receiving UE is within a pre-set threshold. Additionally / alternatively, FDM of HARQ feedback resources can be allowed or configured only for receiving UEs whose SL RSRQ difference in the link between the transmitting UE and the receiving UE is within a pre-set threshold.

[0151] When the distance difference between the multiple receiving UEs and the transmitting UE is within a pre-set threshold, the multiple receiving UEs can transmit HARQ feedback through frequency division multiplexing resources on the frequency axis. Additionally / alternatively, when the pathloss difference between the multiple receiving UEs and the transmitting UE is within a pre-set threshold, the multiple receiving UEs can transmit HARQ feedback through frequency division multiplexing resources on the frequency axis. Additionally / alternatively, when the (measured) RSRP value difference between the multiple receiving UEs and the transmitting UE is within a pre-set threshold, the multiple receiving UEs can transmit HARQ feedback through frequency division multiplexing resources on the frequency axis. Additionally / alternatively, when the (measured) RSRQ value difference between the multiple receiving UEs and the transmitting UE is within a pre-set threshold, the multiple receiving UEs can transmit HARQ feedback through frequency division multiplexing resources on the frequency axis.

[0152] FDM of HARQ feedback resources can not be desired among subgroups or UEs within a group. FDM of HARQ feedback resources can not be desired among different subgroups or different UEs within a group when power control related to HARQ feedback transmission is not applied. FDM of HARQ feedback resources can not be desired among different subgroups or different UEs within a group when the difference of HARQ feedback reception power between the different subgroups or different UEs within the group is greater than a pre-set threshold. FDM of HARQ feedback resources can not be desired among different subgroups or different UEs within a group when the difference of SL pathloss between the different subgroups or different UEs within the group is greater than a pre-set threshold. FDM of HARQ feedback resources can not be desired among different subgroups or different UEs within a group when the SL RSRP difference between the different subgroups or different UEs within the group is greater than a pre-set threshold. FDM of HARQ feedback resources can not be desired among different subgroups or different UEs within a group when the SL RSRQ difference between the different subgroups or different UEs within the group is greater than a pre-set threshold.

[0153] As shown in the above examples, when it is not desired to frequency-division multiplex the HARQ feedback resources, the HARQ feedback resources can be pseudo-randomly frequency-division multiplexed based on at least one of the GUE_ID, the receiving UE related identifier, the SL HARQ process ID, and / or the transmitting UE related identifier. The HARQ feedback resources can be pseudo-randomly determined based on at least one of the GUE_ID, the receiving UE related identifier, the SL HARQ process ID, and / or the transmitting UE related identifier. For example, the HARQ feedback resources can be frequency-division multiplexed or determined by a function with at least one of the GUE_ID, the receiving UE related identifier, the SL HARQ process ID, and / or the transmitting UE related identifier as an input parameter. The HARQ feedback resources can be the HARQ feedback resources for each of the plurality of UEs in the group. The HARQ feedback resources can be the HARQ feedback resources for each subgroup in the group. For example, the receiving UE related identifier can be a destination ID. The transmitting UE related identifier can be a source ID. The function can be predefined.

[0154] The transmitting UE can transmit a PSCCH and / or a PSSCH to the receiving UE. The transmitting UE can transmit SL information to the receiving UE by using a PSCCH resource and / or a PSSCH resource. The SL information can include at least one of SL control information, SL data, a SL packet, a SL transport block (TB), a SL message, and / or a SL service.

[0155] The receiving UE can determine the HARQ feedback resources. In addition, the transmitting UE can determine the HARQ feedback resources. For example, the receiving UE can be one of the plurality of UEs performing groupcast communication within the group.

[0156] The HARQ feedback resources can be determined based on at least one of a PSCCH resource, a PSSCH resource, and / or a GUE_ID. When the plurality of receiving UEs in the group feed back a HARQ ACK or a HARQ NACK to the transmitting UE by using different PSFCH resources, the plurality of receiving UEs in the group can determine the HARQ feedback resources by using the GUE_ID. The resources can include at least one of a time domain resource, a frequency domain resource, and / or a code domain resource. The GUE_ID can be information for identifying the UEs in the group.

[0157] The receiving UE can transmit a HARQ feedback to the transmitting UE. The receiving UE can transmit a HARQ feedback corresponding to a PSCCH and / or a PSSCH to the transmitting UE. For example, the receiving UE can transmit a HARQ feedback to the transmitting UE by using the HARQ feedback resources determined based on at least one of a PSCCH resource, a PSSCH resource, and / or a GUE_ID.

[0158] When the receiving UE successfully receives the PSCCH and / or the PSSCH, the HARQ feedback can be a HARQ ACK. When the receiving UE fails to receive the PSCCH and / or the PSSCH, the HARQ feedback can be at least one of a HARQ NACK and / or a discontinuous detection (DTX).

[0159] When the transmitting UE selects the PSSCH and / or the PSCCH transmission resource through the sensing operation, a collision between the HARQ feedback transmission related resources can not occur. When a plurality of transmitting UEs select different PSSCH and / or PSCCH transmission resources through the sensing operation, the HARQ feedback resources can be determined based on the PSSCH resources and / or the PSCCH resources. Accordingly, a collision between the HARQ feedback resources can be automatically avoided between the UEs that select different PSSCH and / or PSCCH transmission resources based on the sensing operation.

[0160] When the transmitting UE transmits the same PSSCH and / or PSCCH to a plurality of receiving UEs in a group, the plurality of receiving UEs can determine the HARQ feedback resources by using different GUE_IDs. Accordingly, even if the plurality of receiving UEs in the group receive the same PSSCH and / or PSCCH, a collision between the HARQ feedback resources can be prevented.

[0161] Figure 12 An example of a process for transmitting and receiving HARQ feedback on a PSCCH and / or a PSSCH in a groupcast SL communication is illustrated.

[0162] Referring to Figure 12 An ID for identifying a UE within a group can be assigned / designated to a plurality of UEs in the group. The ID can be referred to as an internal ID. The internal ID can be a destination or a parameter such as a GUE_ID. For example, with respect to a specific groupcast service, an application layer can transmit information about an internal ID of a UE and information about a number of UEs in a group to a V2X layer. The UE can be a UE that transmits a specific groupcast service. With respect to the specific groupcast service, the application layer can not transmit information about an internal ID of another UE in the group to the V2X layer. The groupcast service can include at least one of a groupcast service, a groupcast data, a groupcast packet, and / or a groupcast message.

[0163] When the transmitting UE wants to transmit the first service related to groupcast to multiple receiving UEs in the group, the application layer of the transmitting UE can transmit information about the internal ID of the transmitting UE and information about the number of UEs in the group to the V2X layer of the transmitting UE. The application layer of the receiving UE 1 can transmit information about the internal ID of the receiving UE 1 and information about the number of UEs in the group to the V2X layer of the receiving UE 1. The application layer of the receiving UE 2 can transmit information about the internal ID of the receiving UE 2 and information about the number of UEs in the group to the V2X layer of the receiving UE 2. The application layer of the receiving UE 3 can transmit information about the internal ID of the receiving UE 3 and information about the number of UEs in the group to the V2X layer of the receiving UE 3. The application layer of the receiving UE 4 can transmit information about the internal ID of the receiving UE 4 and information about the number of UEs in the group to the V2X layer of the receiving UE 4.

[0164] The V2X layer of the UE can transmit information about the internal ID of the UE and information about the number of UEs in the group to the AS layer of the UE. In addition, for example, the V2X layer of the UE can also transmit the L2 ID (e.g., source L2 ID or destination L2 ID) and / or QoS information to the AS layer of the UE.

[0165] The transmitting UE can transmit the specific groupcast service to the multiple receiving UEs (S2110). The specific groupcast service can be transmitted through the PSSCH and / or the PSCCH.

[0166] The multiple receiving UEs can determine the HARQ feedback resource (S2120). According to the predefined rule, the multiple receiving UEs (e.g., the AS layer of the multiple receiving UEs) can determine the resource for the HARQ feedback on the specific groupcast service based on the information about the internal ID thereof and the information about the number of UEs in the group.

[0167] The transmitting UE can determine the resource for the HARQ feedback (transmitted by the transmitting UE). The transmitting UE can derive or determine the resource for the HARQ feedback from the multiple receiving UEs related to the specific groupcast service based on the information about the internal ID thereof and the information about the number of UEs in the group.

[0168] When the application layer provides the V2X layer of the UE with information about the internal ID of the UE and information about the number of UEs in the group, the UE can determine or consider groupcast option 1 or groupcast option 2 as the (optional) HARQ feedback option for the specific groupcast service. The V2X layer of the UE can determine or consider groupcast option 1 or groupcast option 2 as the (optional) HARQ feedback option for the specific groupcast service. Furthermore, the UE can finally determine or consider groupcast option 1 or groupcast option 2 as the HARQ feedback option for the specific groupcast service depending on whether a pre-defined condition is fulfilled or not. When all HARQ feedback resources for the multiple UEs participating in the groupcast are supported in the resource pool, respectively, the UE can finally determine or consider groupcast option 2 as the HARQ feedback option for the specific groupcast service. When not all HARQ feedback resources for the multiple UEs participating in the groupcast are supported in the resource pool, respectively, the UE can finally determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast service. This determination can be performed in the AS layer of the UE.

[0169] When the application layer does not provide the V2X layer of the UE with information about the number of UEs in the group, the UE can determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast service. When the application layer does not provide the V2X layer of the UE with information about the internal ID of the UE and / or information about the number of UEs in the group, the UE can determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast service. For example, the V2X layer of the UE can determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast service.

[0170] When the application layer and / or the V2X layer provide the AS layer of the UE with information about the internal ID of the UE and information about the number of UEs in the group, the UE can determine or consider groupcast option 1 or groupcast option 2 as the (optional) HARQ feedback option for the specific groupcast service. The AS layer of the UE can determine or consider groupcast option 1 or groupcast option 2 as the (optional) HARQ feedback option for the specific groupcast service. Furthermore, the UE can finally determine or consider groupcast option 1 or groupcast option 2 as the HARQ feedback option for the specific groupcast service depending on whether a pre-defined condition is fulfilled or not. When all HARQ feedback resources for the multiple UEs participating in the groupcast are supported in the resource pool, respectively, the UE can finally determine or consider groupcast option 2 as the HARQ feedback option for the specific groupcast service. When not all HARQ feedback resources for the multiple UEs participating in the groupcast are supported in the resource pool, respectively, the UE can finally determine or consider groupcast option 1 as the HARQ feedback option for the specific groupcast service. This determination can be performed in the AS layer of the UE.

[0171] When the application layer and / or the V2X layer does not provide the AS layer of the UE with information about the number of UEs in the group, the UE can determine or consider groupcast option 1 as a HARQ feedback option for a certain groupcast service. When the application layer and / or the V2X layer does not provide the AS layer of the UE with information about the internal ID of the UE and / or information about the number of UEs in the group, the UE can determine or consider groupcast option 1 as a HARQ feedback option for a certain groupcast service. For example, the AS layer of the UE can determine or consider groupcast option 1 as a HARQ feedback option for a certain groupcast service.

[0172] At least one of groupcast option 1 and / or groupcast option 2 can be signaled to the UE in a resource pool-specific manner. At least one of groupcast option 1 and / or groupcast option 2 can be signaled to the UE according to a type of service, a type of broadcast, or a QoS requirement in a resource pool-specific manner. Whether PSFCH resources related to groupcast option 1 are configured can be signaled to the UE according to a type of service, a type of broadcast, or a QoS requirement in a resource pool-specific manner. Whether PSFCH resources related to groupcast option 2 are configured can be signaled to the UE according to a type of service, a type of broadcast, or a QoS requirement in a resource pool-specific manner.

[0173] A transmitting UE can receive HARQ feedback from a plurality of receiving UEs. The transmitting UE can receive HARQ feedback from a plurality of receiving UEs based on groupcast option 1. For example, the transmitting UE can receive HARQ feedback based on groupcast option 2 from a plurality of receiving UEs.

[0174] For a certain groupcast service, a HARQ feedback operation based on a certain groupcast option can be required. In the case of a high reliability requirement related to a service, when a transmitting UE transmits the service to a receiving UE, the receiving UE needs to perform a HARQ feedback operation based on groupcast option 2. If the receiving UE performs a HARQ feedback operation on the service based on groupcast option 1, DTX can occur, and thus the receiving UE needs to perform a HARQ feedback operation on the service with a high reliability requirement based on groupcast option 2. DTX can be a problem in which the transmitting UE misinterprets that the receiving UE has successfully received a PSCCH and a PSSCH when the receiving UE fails to receive the PSCCH and does not transmit a NACK to the transmitting UE. Due to DTX, it can be difficult to satisfy a reliability requirement of the service. Thus, if a certain groupcast option is not supported on a resource pool, or if a certain groupcast option is not supported for a service and / or a service, the transmitting UE can perform a blind retransmission operation. If PSFCH resources related to a certain groupcast option are not configured, the transmitting UE can perform a blind retransmission operation. The transmitting UE can perform a retransmission without receiving HARQ feedback from the receiving UE.

[0175] Figure 13 FIG. illustrates a configuration of PSCCH / PSSCH / PSFCH in a slot. Refer to Figure 13 , the time position of PSFCH in one slot can be TDMed with PSCCH / PSSCH.

[0176] Figure 14 FIG. illustrates a sidelink SSB (S-SSB) structure. Refer to Figure 14 , a UE can transmit an S-SSB in order to synchronize with other UEs via a sidelink. For the order of symbols mapping a sidelink primary synchronization signal (S-PSS), a sidelink secondary synchronization signal (S-SSS), and a physical sidelink broadcast channel (PSBCH) in an S-SSB, refer to Figure 14 .

[0177] Figure 15 FIG. illustrates an example of a method performed by a sidelink UE to determine a PSFCH resource.

[0178] Figure 15 FIG. illustrates a case where a PSFCH period of 4 slots in an upper layer, a minimum time gap from a reception of a PSSCH to a transmission of a PSFCH in 2 slots, a PSFCH resource type according to a number of PSSCH sub-channels, and two cyclic shift (CS) pairs are configured. Also, Figure 15 FIG. illustrates a case where a PSFCH transmitting UE transmits PSSCHs (i.e., PSSCH 2 and PSSCH 6) by using two sub-channels in a second slot. In this case, the PSFCH transmitting UE can determine an appropriate resource according to an ID (Tx ID or P_ID) of a transmitting UE and an ID (Rx ID or M_ID) of a receiving UE among 10 PRBs corresponding to the 2nd and 6th numbers in a PSFCH occasion and 2 CS pairs configured in the 6th slot according to the PSFCH resource configuration rule defined in 3GPP TS 38.213, i.e., a total of 20 candidate resources (i.e., R PSFCH PRB,cs = 20). This figure shows a case where a result of (Tx ID + Rx ID) mod 20 according to 3GPP TS 38.213 is 17, and shows that the third PRB of the sixth PRB group and the second CS pair (i.e., CS = 3 in the case of NACK, and CS = 9 in the case of ACK) are used for a PSFCH transmission. Except for a case where groupcast requires ACK / NACK feedback, the value of Rx ID is configured to 0.

[0179] <Method of communicating in unlicensed band>

[0180] Figure 16 FIG. illustrates a service environment of new radio unlicensed (NR-U).

[0181] Refer to Figure 16 A user can be provided with a service environment of NR technology 11 in an existing licensed band and NR technology 12 in an unlicensed band (i.e., NR-U). For example, in an NR-U environment, NR technology 11 in a licensed band and NR technology 12 in an unlicensed band can be integrated using a technology such as carrier aggregation, which can contribute to expansion of network capacity. In addition, in an asymmetric traffic structure having more downlink data than uplink data, NR-U can provide NR services optimized for various needs or environments. For convenience, NR technology in a licensed band is referred to as NR-L (licensed NR), and NR technology in an unlicensed band is referred to as NR-U (unlicensed NR).

[0182] Figure 17 A conventional communication scheme (e.g., wireless LAN) operating in an unlicensed band is illustrated. Since most devices operating in an unlicensed band are based on "listen before talk" (LBT) operation, a clear channel assessment (CCA) technique of sensing a channel before data transmission is performed.

[0183] Reference Figure 17 A wireless LAN device (e.g., an AP or a STA) checks whether a channel is busy by performing carrier sensing before transmitting data. When a radio signal of a predetermined strength or higher is sensed in a channel to transmit data, it is determined that the corresponding channel is busy, and the wireless LAN device delays access to the corresponding channel. Such a process is referred to as clear channel assessment, and a signal level used to decide whether a signal is sensed is referred to as a CCA threshold. Meanwhile, when no radio signal is sensed in the corresponding channel or when a radio signal of a strength less than the CCA threshold is sensed, it is determined that the channel is idle.

[0184] When it is determined that a channel is idle, a terminal having data to transmit performs a backoff procedure after a defer duration (e.g., an arbitration interframe space (AIFS), a PCFIFS (PIFS), etc.). The defer duration indicates the shortest time that the terminal needs to wait after a channel is idle. The backoff procedure allows the terminal to further wait for a predetermined time after the defer duration. For example, the terminal prepares for access to the corresponding channel while reducing a time slot corresponding to a random number assigned to the terminal in a contention window (CW) during which the channel is idle, and a terminal that completely exhausts the time slot can attempt to access the corresponding channel.

[0185] When the terminal successfully accesses the channel, the terminal can transmit data through the channel. After the data is successfully transmitted, the CW size (CWS) is reset to the initial value (CWmin). In contrast, when the data is not successfully transmitted, the CWS is doubled. As a result, a new random number is allocated to the terminal in a range twice as large as the previous random number range to perform a backoff procedure in the next CW. In the wireless LAN, only ACK is defined as response information received with respect to data transmission. Therefore, when ACK is received with respect to data transmission, the CWS is reset to the initial value, and when feedback information is not received with respect to data transmission, the CWS is doubled.

[0186] As described above, since existing communications in the unlicensed band mainly operate based on LBT, channel access in the NR-U system also performs LBT to coexist with existing devices. Specifically, according to the presence / absence / application method of LBT, a channel access method on the unlicensed band in NR can be classified into the following four categories.

[0187] • Category 1: No LBT

[0188] The Tx entity does not perform an LBT procedure for transmission.

[0189] • Category 2: LBT without random backoff

[0190] The Tx entity senses whether a channel is idle during a first interval without random backoff to perform transmission. That is, the Tx entity can perform transmission through the channel immediately after sensing that the channel is idle during the first interval. The first interval is an interval of a predetermined length immediately before the Tx entity performs transmission. According to an embodiment, the first interval can be an interval of 25 μs in length, but the present application is not limited thereto.

[0191] • Category 3: LBT with random backoff using a fixed size CW

[0192] The Tx entity obtains a random value within a fixed size CW, sets it as an initial value N of a backoff counter (or backoff timer), and performs backoff by using the set backoff counter N. During the backoff procedure, every time it is detected that the channel is in an idle state for a predetermined slot period, the Tx entity decreases the backoff counter by 1. Here, the predetermined slot period can be 9 μs, but the present application is not limited thereto. The backoff counter N is decreased by 1 from the initial value, and when the value of the backoff counter N reaches 0, the Tx entity can perform transmission. Meanwhile, in order to perform backoff, the Tx entity first senses whether a channel is idle for a second interval (i.e., a defer duration T d) is idle. According to an embodiment of the present application, the Tx entity can sense (determine) whether the channel is idle during the second interval according to whether the channel is idle for at least some period (e.g., a slot period) within the second interval. The second interval can be set based on the channel access priority class of the Tx entity, and consists of a period of 16μs and m consecutive slot periods. Here, m is a value set according to the channel access priority class. When the channel is sensed to be idle during the second interval, the Tx entity performs channel sensing to reduce the backoff counter. On the other hand, when the channel is sensed to be busy during the backoff procedure, the backoff procedure is stopped. After the backoff procedure is stopped, the Tx entity can resume the backoff when the channel is sensed to be idle for an additional second interval. In this way, the Tx entity can perform a transmission when the channel is idle during the slot period of the backoff counter N in addition to the second interval. In this case, the initial value of the backoff counter N is obtained within a CW of a fixed size.

[0193] • Category 4: LBT performs random backoff by using a CW of variable size

[0194] The Tx entity obtains a random value within a CW of variable size, sets the random value as the initial value of the backoff counter (or backoff timer) N, and performs backoff by using the set backoff counter N. More specifically, the Tx entity can adjust the size of the CW based on HARQ-ACK information for a previous transmission, and obtain the initial value of the backoff counter N within the CW of the adjusted size. The specific procedure of performing backoff by the Tx entity is as described in Category 3. In addition to the second interval, the Tx entity can perform a transmission when the channel is idle during the slot period of the backoff counter N. In this case, the initial value of the backoff counter N is obtained within a CW of variable size.

[0195] In the above Category 1 to Category 4, the Tx entity can be a base station or a UE. According to an embodiment of the present application, the first type of channel access can refer to the channel access of Category 4, and the second type of channel access can refer to the channel access of Category 2.

[0196] Figure 18 FIG. illustrates a channel access procedure based on Category 4 LBT according to an embodiment of the present application.

[0197] To perform channel access, first, the Tx entity performs channel sensing (S302) for a defer duration T d According to an embodiment of the present application, the channel sensing for the defer duration T d in step S302 can be performed by channel sensing for at least a portion of the defer duration T d For example, the channel sensing for the defer duration T dchannel sensing during a time slot period within the defer duration T d channel sensing. The Tx entity checks whether the channel is idle by channel sensing during a defer duration T d d If the channel is sensed to be idle during the defer duration T d , the Tx entity returns to step S302. The Tx entity repeats steps S302 to S304 until the channel is sensed to be idle during the defer duration T d d The defer duration T d is set based on the channel access priority class of the Tx entity, and the defer duration T d is composed of a period of 16 μs and m consecutive time slot periods. Here, m is a value set according to the channel access priority class.

[0198] Next, the Tx entity obtains a random value within a predetermined CW, sets the random value as an initial value N of a backoff counter (or backoff timer) (S306), and proceeds to step S308. The initial value of the backoff counter N is randomly selected from among values between 0 and CW. The Tx entity performs a backoff procedure by 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, Figure 18 S306 is illustrated as being performed after the channel is sensed to be idle during the defer duration T d , but the present application is not limited thereto. That is, step S306 can be performed independently of steps S302 to S304, and can be performed before steps S302 to S304. When step S306 is performed before steps S302 to S304, if the channel is sensed to be idle during the defer duration T d by steps S302 to S304, the Tx entity proceeds to step S308.

[0199] In step S308, the Tx entity checks 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 to perform transmission. If the value of the backoff counter N is not 0, the Tx entity proceeds to step S310. In step S310, the Tx entity decreases the value of the backoff counter N by 1. According to an embodiment, the Tx entity can selectively decrease the value of the backoff counter by 1 in the channel sensing process of each time slot. In this case, step S310 can be skipped at least once by the selection of the Tx entity. Next, the Tx entity performs channel sensing for an additional time slot period (S312). The Tx entity checks whether the channel is idle through channel sensing for the additional time slot period (S314). If it is sensed that the channel is idle for the additional time slot period, the Tx entity returns to step S308. In this way, the Tx entity can decrease the backoff counter by 1 whenever the channel is sensed to be idle for a predetermined time slot period. Here, the predetermined time slot period can be 9μs, but the present application is not limited thereto.

[0200] In step S314, if the channel is not sensed to be idle (i.e., sensed to be busy) for the additional time slot period, the Tx entity proceeds to step S316. In step S316, the Tx entity checks whether the channel is idle for an additional deferral duration T d According to an embodiment of the present application, channel sensing in step S316 can be performed in units of time slots. That is, the Tx entity checks whether the channel is sensed to be idle during all time slot periods of the additional deferral duration T d When a time slot is detected to be busy for the additional deferral duration T d , the Tx entity immediately restarts step S316. When the channel is sensed to be idle during all time slot periods of the additional deferral duration T d , the Tx entity returns to step S308.

[0201] On the other hand, if the value of the backoff counter N is 0 in the check of step S308, the Tx entity performs transmission (S320). The Tx entity receives HARQ-ACK feedback corresponding to the transmission (S322). The Tx entity can check whether the previous transmission is successful through 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).

[0202] As described above, after sensing that the channel is idle for the deferral duration T d , the Tx entity can perform transmission when the channel is idle for N additional time slot periods. As described above, the Tx entity can be a base station or a UE, and Figure 18The channel access procedure of the wireless communication device can be used for downlink transmission of the base station and / or uplink transmission of the UE.

[0203] Figure 19 A channel access procedure performed by a wireless communication device in an unlicensed band, and an LBT procedure used when the wireless communication device performs channel access in the unlicensed band, are illustrated. In particular, an LBT procedure used when a wireless communication device according to an embodiment of the present application performs channel access in an unlicensed band will be described. In particular, a channel access in which the wireless communication device performs transmission according to a result of channel sensing for a predetermined duration of a time interval can be configured in the wireless communication device. In this case, a method for operating the wireless communication device when the wireless communication device fails to access a channel will be described. The specified duration mentioned earlier can be 16 μs.

[0204] For convenience of description, the wireless communication device that is a wireless endpoint that initiates channel occupancy will be referred to as an initiating node. In addition, the wireless communication device that is a wireless endpoint that communicates with the initiating node will be referred to as a responding node. The initiating node can be a base station, and the responding node can be a UE. In addition, the initiating node can be a UE, and the responding node can be a base station. When the initiating node is to transmit data, the initiating node can perform channel access according to a channel access priority class determined according to a type of the data. In this case, parameters for channel access can be determined according to the type of the data. The parameters for channel access can include any one of a minimum value of a CW, a maximum value of a CW, a maximum channel occupancy time (MCOT) that is a maximum duration in which a channel can be occupied in one channel occupancy, and a number of sensing slots (m p ) in particular, the initiating node can perform the above-described category 4 LBT according to a channel access priority class determined according to a type of the data.

[0205] Table 1 below shows an example of parameter values for channel access according to a channel access priority class. In particular, Table 1 shows parameter values for channel access for each channel access priority class for downlink transmission in an LTE LAA system.

[0206] When a downlink channel transmitted by the wireless communication device includes data traffic, a defer duration can be configured according to a channel access priority class of traffic included in the downlink channel. In addition, the defer duration can include an initial duration T f or one or more (m p ) slot durations T sl . In this case, the slot duration T sl may be 9 μs. The initial duration includes one idle slot duration T slIn addition, the number of slot durations (m p ) included in the deferral duration can be configured according to the channel access priority class as described above. p Specifically, the number of slot durations (m p ) included in the deferral duration can be configured as shown in Table 1.

[0207] [Table 1]

[0208]

[0209] The wireless communication device can configure a range of CW values according to the channel access priority class. Specifically, the wireless communication device can set the value of CW to satisfy CW min,p <= CW <= CW max,p In this case, the minimum value CW min,p and the maximum value CW max,p of CW can be determined according to the channel access priority class. Specifically, the minimum value CW min,p and the maximum value CW max,p of CW can be determined as shown in Table 1. Referring to Figure 17 , the wireless communication device selects a random counter value within the CW value, and can adjust the CW value (i.e., CW size) according to whether the channel access (or channel transmission) is successful. For example, when the channel access (or channel transmission) is successful, the wireless communication device can reset the current CW value to the minimum value for each CAPC. When the channel access (or channel transmission) fails, the wireless communication device can configure the current CW value to the next highest possible value within the maximum range of values for each CAPC.

[0210] In addition, in the wireless communication device of the unlicensed band, MCOT T mcot，p may be determined according to the channel access priority of the data included in the transmission as described above. Specifically, MCOT can be determined as shown in Table 1. Accordingly, the wireless communication device can not be allowed to perform a continuous transmission for a time exceeding the MCOT in the unlicensed band. This is because the unlicensed band is a frequency band used by various wireless communication devices according to a certain rule. In Table 1, when the value of the channel access priority class is p = 3 or p = 4, the unlicensed band is long-term used by regulation, and there is no wireless communication device using other technologies, the wireless communication device can be configured with T mcot,p = 10 ms. Otherwise, the wireless communication device can be configured with T mcot,p = 8 ms.

[0211] Table 2 shows the parameter values for channel access of each channel access priority class for uplink transmission used in the LTE LAA system.

[0212] [Table 2]

[0213]

[0214] As described in Table 2, when one or more gaps are included in the transmission, the MCOT value of 6 ms can be increased to 8 ms. The gap indicates a time from stopping transmission in a carrier until resuming transmission in the carrier. In this case, the minimum value of the gap duration is 100 µs. Also, the maximum value of the transmission duration performed before including the gap is 6 ms. Also, the duration of the gap is not included in the channel occupancy time. When the value of the channel access priority class is 3 or 4, and it is guaranteed that no other radio access technology is used in the carrier in which the channel access is performed, the value of the MCOT can be 10 ms. In this case, another wireless access technology can include Wi-Fi. Otherwise, the value of the MCOT can be determined as described in Note 1 of Table 2.

[0215] COT indicates a time that a wireless communication device occupies a channel. As described above, MCOT indicates a maximum time that an initiating node can continuously occupy a channel in any one carrier of an unlicensed band. However, as described above, a gap that is an interval in which no transmission is performed can be included between a plurality of transmissions, and when the gap is included, the value of the MCOT can be applied differently.

[0216] <Embodiment: Channel access for sidelink (SL) transmission>

[0217] First, terms used herein will be described.

[0218] - Type 1 channel access procedure (CAP): a channel access procedure with random backoff (see Figure 17 ). Channel sensing can be performed based on a random value selected within a CW. If it is determined that a channel is idle as a result of performing channel access, SL transmission can be performed.

[0219] - Type 2 CAP: a channel access procedure without random backoff. For channel transmission, channel sensing can be performed during a fixed-length sensing interval. According to the fixed-length sensing interval, it can be classified as Type 2A / 2B / 2C.

[0220] - CO (or COT): CO means that a wireless communication device (e.g., UE) initiates transmission in a channel and occupies the channel. COT means channel occupancy time.

[0221] - COT sharing: means that a COT initiated by a wireless communication device (e.g., UE) is shared with the same / different wireless communication device (e.g., see Figure 19 ).

[0222] - SL transmission: The SL transmission includes transmission of SL channels. The SL channels include a physical sidelink control channel (PSCCH), a physical sidellink shared channel (PSSCH), a physical sidelink feedback channel (PSFCH), etc.

[0223] - PSCCH / PSSCH: It refers to the PSSCH and / or the PSSCH.

[0224] - Sidelink control information (SCI): The SCI can be divided into a first SCI (or SCI format 1) and a second SCI (or SCI format 2). The first SCI is transmitted through the PSCCH. The first SCI is used to schedule (i) the PSSCH and (ii) the second SCI on the PSSCH. For example, the first SCI includes time / frequency resource information for PSSCH reception, a priority indicator, second SCI format information, etc. The priority indicator indicates the traffic priority of the PSSCH. The first SCI can be decoded by all UEs in the cell for channel sensing. However, the second SCI is decoded by each receiving UE, and includes the remaining information required to decode the PSSCH. The second SCI can be transmitted using the PSSCH resource. For example, the second SCI includes a HARQ process number, a cast type indicator, a source ID, a destination ID, etc.

[0225] Channel access for multiple SL transmission

[0226] As shown in Figure 9 , the SL transmission can be transmitted / received between multiple UEs. For example, one Tx UE can perform multiple SL transmissions to multiple Rx UEs, or multiple Rx UEs can simultaneously perform SL transmissions.

[0227] Meanwhile, when performing the SL transmission in the unlicensed band, the UE can perform a channel access procedure (CAP) to transmit the SL transmission. For example, the UE can perform a Type 1 CAP to transmit the SL transmission (see Figures 17 to 18 ). The Type 1 CAP is performed using parameters for channel access (e.g., CW), and the parameters for channel access can be defined for each CAP C value (see Tables 1 to 2). The CAP C value indicates the priority of the parameters for channel access (or channel access parameters). For example, referring to Table 1, the CAP C value corresponds to the CWmin and CWmax, and the higher the CAP C value, the higher the CWmin and CWmax. Therefore, the higher the CAP C value, the lower the channel access priority of the UE, because the counter value for random backoff is selected within a wider CW range. The CAP C value used when transmitting the SL can be determined based on the priority of the SL transmission.

[0228] Figure 20 illustrates a problem when performing multiple SL transmissions.

[0229] Referring to Figure 20 Multiple SL transmissions can be scheduled within a slot. Here, the multiple SL transmissions can be scheduled to be transmitted from one UE, or can be scheduled to be transmitted from two or more different UEs. Here, the SL transmissions include Figures 13 and 14 transmissions of SL channels as shown in FIG. 2. For example, the SL channels can include at least one of PSCCH, PSSCH, PSFCH, and PSBCH. In this case, each SL transmission can be associated with a respective CAPC value. For example, CAPC#a can be associated with SL transmission #1, and CAPC#b can be associated with SL transmission #2. Here, CAPC#a and CAPC#b can be different. In this case, Type 1 CAP can be performed by using channel access parameters with different priorities for each SL transmission in order to transmit the multiple SL transmissions. Thus, a SL transmission using channel access parameters with a low priority can be affected by a SL transmission using channel access parameters with a high priority. For example, if SL transmission #1 succeeds in channel access and is transmitted, Type 1 CAP for SL #2 can fail due to the transmission of SL transmission #1.

[0230] Hereinafter, a channel access method for transmitting multiple SL transmissions simultaneously (e.g., in one slot) is described. To help understanding of the present disclosure, PSFCH transmission is used as an example of SL transmission. However, the present disclosure can also be applied to the case where channel access is performed to transmit multiple different SL channels (see Figures 13 and 14 ) within one slot.

[0231] Hereinafter, a method of configuring CAPC when multiple PSFCHs are transmitted in the same PSFCH occasion within a slot is described in detail by dividing cases. Here, the PSFCH occasion indicates a time / frequency resource for PSFCH transmission (e.g., see Figure 10 and Figure 15 ).

[0232] 1. A method for determining CAPC by a UE when one UE transmits multiple SL channels (e.g., PSFCH) to another UE

[0233] When one UE transmits two or more PSFCHs to different UEs at the same PSFCH occasion, the CAPC value for each PSFCH can be independently configured based on the traffic priority corresponding to the PSSCH transmitted from the different UEs. Accordingly, the CAPC value for each PSFCH can be differently configured. In this case, the transmission of another PSFCH performing backoff by setting the CW size relatively long (i.e., higher CAPC value = lower priority) can be affected by the transmission of a PSFCH that is successful in channel access by setting the CW size short (i.e., lower CAPC value = higher priority). For example, some of the transmissions intended from one UE among the two or more PSFCHs can not occur. Accordingly, when one UE transmits two or more PSFCHs to different UEs at the same PSFCH occasion, a CAPC configuration method resolving the collision between the PSFCH transmissions within one UE should be discussed.

[0234] At least one UE can have two or more PSFCH transmissions intended to be transmitted to different UEs at the same PSFCH occasion. Here, the priority of the PSFCH transmissions follows the traffic priority of the PSSCH corresponding to the PSFCH transmissions, and the traffic priority of the PSSCH can be known by decoding the SCI of the PSCCH. The following method can be considered a CAPC configuration method applied during a channel access procedure (CAP) for different PSFCH transmissions to address a collision that can occur in the channel access procedure (CAP) of PSFCH transmissions transmitted by one UE to two or more different UEs at the same PSFCH occasion. When a channel access procedure (CAP) is performed for two or more PSFCH transmissions, a common CAPC value can be configured to perform type 1 channel access, and one UE can transmit two or more PSFCHs at the same PSFCH occasion. In this case, when one UE transmits PSFCH, the transmission of different PSFCHs is less affected. Therefore, PSFCH transmission failure due to PSFCH collision that can occur when each PSFCH transmission transmitted by one UE uses different channel access parameters can be avoided. As a method for commonly configuring one CAPC value when type 1 channel access is performed for multiple PSFCH transmissions, when one UE configures a CAPC for each PSFCH according to the traffic priority of each PSSCH transmitted from different UEs, the highest CAPC value (i.e., the lowest priority) among the CAPC values configured for each PSFCH can be configured as a common CAPC value. Therefore, the UE can perform a type 1 channel access procedure before the start of the PSFCH occasion configured for itself, and if the channel access is successful, the UE can perform transmission of each PSFCH transmitted to different UEs at the start time point of transmitting the same PSFCH. That is, if channel access is successful by performing one type 1 channel access procedure based on the highest CAPC value among multiple CAPC values associated with multiple SL transmissions, the UE can perform multiple SL transmissions in one slot.

[0235] If the channel access is not successful at the start time point of transmitting the same PSFCH, the UE can discard the corresponding PSFCH. Alternatively, if the channel access is not successful at the start time point of transmitting the same PSFCH, the UE can attempt to perform a type 1 channel access procedure at the next PSFCH occasion for PSFCH transmission or a PSFCH occasion that can be additionally configured according to channel access failure, and then perform PSFCH transmission.

[0236] As another method, if different UEs cannot know the traffic priority used for PSFCH transmission in a PSFCH occasion, as a CAPC configuration method for resolving a collision between PSFCH transmissions transmitted by two or more UEs, a fixed value (e.g., lowest CAPC value = highest priority) can be configured to be used as a CAPC value for PSFCH transmission. This can be the simplest method to resolve PSFCH collisions between different UEs.

[0237] Figure 21 SL transmission procedure is illustrated in accordance with examples of the present disclosure.

[0238] Referring to Figure 21 A wireless device (e.g., UE) can determine, for a plurality of sidelink (SL) transmissions within a slot, a channel access priority class (CAPC) value for each SL transmission (S2702). Thereafter, to transmit the plurality of SL transmissions in the slot, the wireless device can perform a Type 1 CAP based on a highest CAPC value among the plurality of CAPC values associated with the plurality of SL transmissions. If the Type 1 CAP is successful, the wireless device can transmit the plurality of SL transmissions to each respective receiving UE. The plurality of SL transmissions can correspond to two or more receiving UEs. Here, each CAPC value is associated with a parameter for channel access, and the higher the CAPC value, the lower the priority for the channel access parameter. Here, the parameter for channel access includes a CW parameter (see, Tables 1-2). For example, the CW parameter can include a CWmin and a CWmax. Further, the plurality of SL transmissions can be scheduled to be transmitted on a same time resource within the slot. Here, the plurality of SL transmissions can include PSFCH transmissions. Further, the plurality of SL transmissions can include a plurality of PSFCH transmissions. Here, the same time resource includes a PSFCH occasion. Here, the CAPC value associated with a PSSCH transmission can be determined based on a traffic priority of the PSSCH corresponding to the PSFCH transmission. Further, the traffic priority can be determined based on priority information within SCI used to schedule the PSSCH.

[0239] Figure 22 Issues in performing multiple SL transmissions are illustrated.

[0240] Referring to Figure 22, the UE can receive PSCCH / PSSCH from multiple other UEs and then perform a procedure for performing multiple PSFCH transmissions within a slot. In this case, each CAPC value can be associated with each PSFCH transmission. For example, CAPC#a can be associated with PSFCH transmission #1 and CAPC#b can be associated with PSFCH transmission #2. The CAPC value associated with the PSFCH transmission can 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 can be determined based on the priority information in the SCI scheduling the PSSCH. For convenience, it is assumed that the value of CAPC#a is greater than CAPC#b. In this case, in order to transmit multiple SL transmissions within a slot, the UE can perform Type 1 CAP based on the highest CAPC value among the multiple CAPC values associated with the multiple SL transmissions. When Type 1 CAP is successful, the UE can transmit multiple PSFCHs (to different UEs).

[0241] 2. A method of determining CAPC by a UE when different UEs transmit PSFCH in the same PSFCH occasion and the CAPC values for PSFCHs configured independently of each other are configured differently

[0242] When different UEs transmit PSFCH in the same PSFCH occasion, the CAPC values for PSFCHs configured independently by different UEs can be configured differently. In this case, there can be a case in which the transmission of another UE performing backoff by setting the CW size relatively long (i.e., higher CAPC value = lower priority) can be affected by the transmission of a UE that is successful in channel access by setting the CW size short (i.e., lower CAPC value = higher priority), and thus the PSFCH transmission of the UE can not occur. Therefore, a CAPC configuration method for resolving a collision that can occur during a channel access procedure (CAP) for PSFCH transmissions transmitted by at least two UEs that can occur in the same PSFCH occasion should be discussed.

[0243] If different UEs can know the traffic priority of PSSCH corresponding to PSFCH transmission in the same PSFCH occasion through decoding SCI of PSCCH, as a CAPC configuration method of two UEs to solve a conflict that can occur during a channel access procedure (CAP) of PSFCH transmission transmitted by two or more UEs, when type 1 channel access is performed for PSFCH transmission, type 1 channel access can be performed by commonly configuring one CAPC value. If each UE performs PSFCH transmission based on a common CAPC value, when each of different UEs transmits PSFCH, the transmission of different UEs can be less affected. Therefore, PSFCH transmission failure due to PSFCH collision that can occur when PSFCH transmission of each UE uses different channel access parameters of different UEs can be avoided. As a method for commonly configuring one CAPC value for PSFCH transmission, the traffic priority for PSSCH transmitted from different UEs can be known by decoding SCI of PSCCH, and when CAPC for each PSFCH is configured according to the traffic priority for each PSSCH, the highest CAPC value (i.e., the lowest priority) among the CAPC configured for each PSSCH can be configured as one common CAPC value. Therefore, type 1 channel access procedure can be performed before the same PSFCH occasion configured for different UEs starts. If channel access is successful, transmission of each PSFCH transmitted by different UEs can be performed at the same start time point of PSFCH transmission configured for different UEs. Specifically, different UEs can perform channel access at the start time point for transmitting the same PSFCH, and the UE or UEs whose channel access is successful can perform PSFCH transmission at the same time. However, the UE whose channel access is not successful can discard transmission of the corresponding PSFCH, or can perform PSFCH transmission after attempting to perform type 1 channel access procedure at the next PSFCH transmission occasion for PSFCH transmission or a PSFCH occasion that can be additionally configured according to channel access failure.

[0244] As another method, if different UEs cannot know the traffic priority for PSFCH transmission in the PSFCH occasion, as a CAPC configuration method for solving a conflict between PSFCH transmissions transmitted by two or more UEs, a fixed value (e.g., lowest CAPC value = highest priority) can be configured to be used as a CAPC value for PSFCH transmission. This can be the simplest method to solve PSFCH collision between different UEs.

[0245] However, regardless of how the CAPC value is configured for each PSFCH transmission, at least the starting time point when the PSFCH is transmitted at the same PSFCH occasion can be configured to be cell-specific. Accordingly, it is possible to substantially minimize the collision of PSFCHs transmitted by different UEs or from the same UE to different UEs. The configuration of the PSFCH transmission starting time point at the PSFCH occasion on a cell-specific basis can be applied to both the case where two or more PSFCHs are transmitted by the same UE to different UEs and the case where different PSFCHs are transmitted by different UEs.

[0246] Although the method and system of the present application have been described in connection with certain embodiments, one or more components or operations of the method and system can be implemented using a computing system having a general hardware architecture.

[0247] The above description of the present application is merely exemplary and those skilled in the art to which the present application pertains will understand that various modifications and changes can be made without changing the technical spirit or essential features of the present application. Therefore, it should be construed that the above-described embodiments are illustrative in all aspects and are not restrictive. For example, various components described as a single type can be implemented in a distributed manner, and likewise, components described as distributed can be implemented in a combined form.

[0248] The scope of the present application is indicated by the appended claims rather than the detailed description, and it should be understood that all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present application.

Claims

1. A user equipment (UE) for use in a wireless communication system, the user equipment comprising: Communication module; as well as a processor, the processor controlling the communication module, Wherein, the processor is configured to: determining, for a plurality of sidelink (SL) transmissions within a time slot, each channel access priority class (CAPC) value for each SL transmission; and A type 1 channel access procedure (CAP) is performed based on a highest CAPC value among a plurality of CAPC values ​​associated with the plurality of SL transmissions for sending the plurality of SL transmissions in the time slot.

2. The UE according to claim 1, wherein: The plurality of CAPC values ​​are associated with each contention window (CW) parameter, and the higher the CAPC value, the lower the channel access priority of the CW parameter.

3. The UE according to claim 1, wherein: The processor is configured to send the plurality of SL transmissions to each corresponding receiving UE when the Type 1 CAP is successful.

4. The UE according to claim 1, wherein: The multiple SL transmissions correspond to two or more receiving UEs. The UE according to claim 1 , wherein: The multiple SL transmissions are scheduled to be sent on the same time resource within the time slot. The UE according to claim 1 , wherein: The multiple SL transmissions are scheduled to be sent on different frequency resources within the time slot.

7. The UE according to claim 1, wherein: The multiple SL transmissions include physical sidelink feedback channel (PSFCH) transmissions.

8. The UE according to claim 6, wherein: The multiple SL transmissions include multiple PSFCH transmissions.

9. The UE according to 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 UE according to claim 9, wherein: The traffic priority is determined based on priority information within sidelink control information (SCI) that schedules the PSSCH.

11. A method for use by a user equipment (UE) in a wireless communication system, the method comprising: determining, for a plurality of sidelink (SL) transmissions within a time slot, each channel access priority class (CAPC) value for each SL transmission; as well as A type 1 channel access procedure (CAP) is performed based on a highest CAPC value among a plurality of CAPC values ​​associated with the plurality of SL transmissions for sending the plurality of SL transmissions in the time slot.

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

13. The method according to claim 11, further comprising: When the Type 1 CAP is successful, the multiple SL transmissions are sent to each corresponding receiving UE.

14. The method according to claim 11, wherein The multiple SL transmissions correspond to two or more receiving UEs.

15. The method according to claim 11, wherein The multiple SL transmissions are scheduled to be sent on the same time resource within the time slot.

16. The method according to claim 11, wherein The multiple SL transmissions are scheduled to be sent on different frequency resources within the time slot.

17. The method according to claim 11, wherein The multiple SL transmissions include physical sidelink feedback channel (PSFCH) transmissions.

18. The method according to claim 16, wherein The multiple SL transmissions include multiple PSFCH transmissions.

19. The method according to 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. The method according to claim 19, wherein The traffic priority is determined based on priority information within sidelink control information (SCI) that schedules the PSSCH.

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