Method and apparatus for performing sidelink communication in unlicensed band

Abstract

A method for performing sidelink communication based on an unlicensed band by a user equipment (UE) in a wireless communication system may include receiving, by the UE, sidelink resource pool configuration information from a base station based on higher layer signaling; generating a sidelink (SL) grant if data is generated in a logical channel (LCH) based on the sidelink resource pool configuration information; selecting a sidelink resource pool according to whether hybrid automatic repeat request (HARQ) feedback is configured to the data generated in the LCH based on the sidelink resource pool configuration information; and selecting a sidelink resource from the selected sidelink resource pool, and performing a sidelink transmission.

Description

Technical Field

[0001] The present disclosure relates to a method and an apparatus for performing sidelink communication in an unlicensed frequency band in a wireless communication system. Background Art

[0003] The International Telecommunication Union (ITU) has developed the International Mobile Telecommunications (IMT) framework and standards. Similarly, continuous discussions on 5th generation (5G) communication are being carried out through a program called "IMT for 2020 and beyond".

[0004] To meet the requirements requested by "IMT for 2020 and beyond", various proposals have been made to support various digital parameter configurations (numerologies) for time - frequency resource unit standards by considering various scenarios, service requirements, and potential system compatibility in the 3rd Generation Partnership Project (3GPP) New Radio (NR) system.

[0005] In addition, to overcome adverse channel environments such as high path loss, phase noise, and frequency offset that occur at high carrier frequencies, the NR system can support the transmission of physical signals / channels through multiple beams. In this way, the NR system can support various applications, such as enhanced mobile broadband (eMBB), massive machine - type communication (mMTC) / ultra - machine - type communication (uMTC), and ultra - reliable and low - latency communication (URLLC).

[0006] In addition, vehicle - to - everything (V2X) communication can be considered, that is, a communication method in which road infrastructure and information (e.g., traffic conditions) are exchanged or shared by communicating with other vehicles during driving. V2X can include, for example, vehicle - to - vehicle (V2V) (which can refer to LTE - based / NR - based communication between vehicles), vehicle - to - pedestrian (V2P) (which can refer to LTE - based / NR - based communication between a vehicle and a user equipment (UE) carried by a user), and vehicle - to - infrastructure / network (V2I / N) (which can refer to LTE - based / NR - based communication between a vehicle and a roadside unit (RSU) / network). The RSU can be a transportation infrastructure entity configured by a base station or a fixed UE, such as an entity that sends speed notifications to vehicles. Summary of the Invention Technical Subject

[0008] The technical subject of the present disclosure relates to a method and an apparatus for performing sidelink (SL) communication in a wireless communication system.

[0009] The technical subject matter of the present disclosure relates to a method and apparatus for configuring sidelink (SL) resource pools in an unlicensed frequency band.

[0010] The technical subject matter of the present disclosure relates to a method and apparatus for selecting an SL resource pool configured in an unlicensed frequency band based on the listen-before-talk (LBT) result.

[0011] The technical subject matter of the present disclosure relates to a method and apparatus for selecting an SL resource pool configured in an unlicensed frequency band based on an LBT counter.

[0012] The technical subject matter of the present disclosure relates to a method and apparatus for selecting an SL resource pool configured in an unlicensed frequency band based on the channel busy rate (CBR).

[0013] The technical subject matter of the present disclosure relates to a method and apparatus for selecting a specific transmission opportunity based on candidate transmission opportunities in a resource pool including multiple LBT bandwidths.

[0014] The technical subject matter of the present disclosure relates to a method and apparatus for controlling a minimum time gap between transmission opportunities by considering the maximum channel occupancy time (MCOT) in an unlicensed frequency band.

[0015] The technical subject matter to be achieved by the present disclosure is not limited to the above technical subject matter, and other technical subject matter not described can be clearly understood by those of ordinary skill in the art to which the present disclosure pertains according to the following description.

[0016] Technical Solution

[0017] According to an aspect of the present disclosure, a method for a user equipment (UE) to perform sidelink communication based on an unlicensed frequency band in a wireless communication system may include: receiving, by the UE, sidelink resource pool configuration information from a base station based on higher layer signaling; generating a sidelink (SL) grant if data is generated in a logical channel (LCH) based on the sidelink resource pool configuration information; selecting a sidelink resource pool based on whether hybrid automatic repeat request (HARQ) feedback is configured for the data generated in the LCH according to the sidelink resource pool configuration information; and selecting a sidelink resource from the selected sidelink resource pool and performing sidelink transmission, wherein the UE performs a listen-before-talk (LBT) operation on the unlicensed frequency band during the process of selecting the sidelink resource pool, and performs the sidelink resource pool selection based on at least one of an LBT result, an LBT failure counter, and a channel busy rate (CBR).

[0018] In addition, according to one aspect of the present disclosure, when the HARQ feedback is configured for the UE, the UE may select a sidelink resource pool from one or more sidelink resource pools in which a physical sidelink feedback channel (PSFCH) is configured, and when the HARQ feedback is not configured for the UE, the UE may select a sidelink resource pool from one or more sidelink resource pools regardless of whether the PSFCH is configured.

[0019] In addition, according to one aspect of the present disclosure, the UE may select a resource pool from among one or more resource pools included in the LBT bandwidth in which the LBT is successful based on the LBT result.

[0020] In addition, according to one aspect of the present disclosure, the UE may select a resource pool from among one or more resource pools included in the LBT bandwidth (in which the LBT counter is less than a preset value) based on the LBT counter.

[0021] In addition, according to one aspect of the present disclosure, when a first sidelink resource pool including a plurality of LBT bandwidths is configured for the UE, at least one candidate transmission opportunity may be configured in the first sidelink resource pool including the plurality of LBT bandwidths based on each LBT bandwidth, and when the first sidelink resource pool is selected based on at least one of the LBT result, the LBT failure counter, and the CBR, the UE may select a first transmission opportunity from among one or more candidate transmission opportunities within the first sidelink resource pool based on at least one of the LBT result, the LBT failure counter, and the CBR.

[0022] Technical effects

[0023] According to the present disclosure, sidelink (SL) communication may be performed in a wireless communication system.

[0024] According to the present disclosure, a method of configuring an SL resource pool in an unlicensed frequency band may be provided.

[0025] According to the present disclosure, a method of selecting an SL resource pool configured in an unlicensed frequency band based on a listen-before-talk (LBT) result may be provided.

[0026] According to the present disclosure, a method of selecting an SL resource pool configured in an unlicensed frequency band based on an LBT counter may be provided.

[0027] According to the present disclosure, a method of selecting an SL resource pool configured in an unlicensed frequency band based on a channel busy ratio (CBR) may be provided.

[0028] According to the present disclosure, a method of selecting a specific transmission opportunity based on candidate transmission opportunities in a resource pool including a plurality of LBT bandwidths may be provided.

[0029] According to the present disclosure, a method of controlling a minimum time gap between transmission opportunities by considering a maximum channel occupancy time (MCOT) in an unlicensed band can be provided.

[0030] The effects to be achieved by the present disclosure are not limited to the above effects, and other technical effects not described can be clearly understood by those of ordinary skill in the art to which the present disclosure pertains based on the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 An example of a new radio (NR) frame structure to which the present disclosure can be applied is shown.

[0033] Figure 2 An NR resource structure to which the present disclosure can be applied is shown.

[0034] Figure 3 An NR sidelink time slot structure to which the present disclosure can be applied is shown.

[0035] Figure 4 An NR sidelink frequency to which the present disclosure can be applied is shown.

[0036] Figure 5 An NR sidelink resource pool configuration to which the present disclosure can be applied is shown.

[0037] Figure 6 An unlicensed band for each area for NR sidelink communication to which the present disclosure can be applied is shown.

[0038] Figure 7 The use of a 5 gigahertz (GHz) unlicensed band to which the present disclosure can be applied is shown.

[0039] Figure 8 A method of increasing bandwidth considering power spectral density (PSD) limitations to which the present disclosure can be applied is shown.

[0040] Figure 9 A method of configuring a guard band considering a shared frequency band within a cell to which the present disclosure can be applied is shown.

[0041] Figure 10 An unlicensed band applicable to the present disclosure is shown.

[0042] Figure 11 A sidelink resource pool to which the present disclosure can be applied is shown.

[0043] Figure 12 A method for a user equipment (UE) operating based on sidelink resource assignment mode 2 applicable to the present disclosure is shown.

[0044] Figure 13Shows a method for operating a sidelink hybrid automatic repeat request (HARQ) entity applicable to the present disclosure.

[0045] Figure 14 Shows a sidelink procedure applicable to the present disclosure.

[0046] Figure 15 Shows a sidelink resource pool configured in a single unlicensed band applicable to the present disclosure.

[0047] Figure 16 Shows a sidelink bandwidth part (SL BWP) configuration operating in a wideband.

[0048] Figure 17 Shows a resource pool selection procedure applicable to the present disclosure.

[0049] Figure 18 Shows a method for a UE to perform resource selection considering the LBT result applicable to the present disclosure.

[0050] Figure 19 Shows a method for selecting a resource pool based on an LBT failure counter applicable to the present disclosure.

[0051] Figure 20 Shows a method for a UE to perform resource selection considering the LBT counter applicable to the present disclosure.

[0052] Figure 21 Shows a method for generating a sidelink grant and selecting a resource based on the channel busy ratio (CBR) applicable to the present disclosure.

[0053] Figure 22 Shows a CBR window in the sidelink unlicensed band applicable to the present disclosure.

[0054] Figure 23 Shows a resource pool configuration in the SL BWP applicable to the present disclosure.

[0055] Figure 24 Shows a method for a UE to perform resource selection considering the LBT counter applicable to the present disclosure.

[0056] Figure 25 Shows a sidelink operation applicable to the present disclosure.

[0057] Figure 26 Shows an SL BWP including a plurality of resource block (RB) sets.

[0058] Figure 27 Shows a method for selecting a transmission opportunity based on candidate transmission opportunities applicable to the present disclosure.

[0059] Figure 28Illustrates a method for determining a transmission opportunity based on LBT operation applicable to the present disclosure.

[0060] Figure 29 Illustrates a case where a minimum time gap is guaranteed in a transmission opportunity applicable to the present disclosure.

[0061] Figure 30 Illustrates a method for determining a transmission opportunity using consecutive time slots in an unlicensed band applicable to the present disclosure.

[0062] Figure 31 Is a flowchart showing a method for a UE to perform sidelink communication to which the present disclosure can be applied.

[0063] Figure 32 Is a flowchart showing a method for a UE to perform sidelink communication to which the present disclosure can be applied.

[0064] Figure 33 Is a diagram showing a base station device and a terminal device to which the present disclosure can be applied. Detailed implementation

[0066] The various examples of the present disclosure will be described more fully below with reference to the drawings, so that those of ordinary skill in the art to which the present disclosure pertains can easily implement these examples. However, the present disclosure can be implemented in various forms and is not limited to the examples described herein.

[0067] When describing the examples of the present disclosure, for clarity and conciseness, detailed descriptions of known configurations or functions may be omitted. Throughout the drawings and the detailed description, unless otherwise stated, the same reference numerals are understood to represent the same elements, features, and structures.

[0068] It will be understood that when an element is referred to as "connected to", "coupled to", or "accessed" another element, it can be directly connected, coupled, or accessed to another element, or there may be an intermediate element. Further, it will be understood that when an element is described as "including / containing" or "having" another element, it specifies the presence of another element, but does not exclude the presence of another element described in other ways.

[0069] In addition, terms such as first, second, etc. may be used herein to describe elements in the description herein. These terms are used to distinguish one element from another. Therefore, the terms do not limit the elements, the order of arrangement, or the sequence, etc. Thus, a first element in one example may be referred to as a second element in another example. Similarly, a second element in one example may be referred to as a first element in another example.

[0070] Here, providing distinguishing elements is merely for clearly explaining each feature, and does not mean that the elements must be separated from each other. That is, multiple elements can be integrated into a single hardware or software unit. Moreover, a single element can be distributed among multiple hardware or software units. Therefore, unless otherwise specifically described, integrated or distributed examples are also included within the scope of the present disclosure.

[0071] Here, the elements described in various examples may not be essential and may be partially optional. Therefore, examples including a partial set of the elements described in the examples are also included within the scope of the present disclosure. In addition, examples further including another element in addition to the elements described in various examples are also included within the scope of the present disclosure.

[0072] The descriptions provided herein relate to a wireless communication network, and the operations performed in the wireless communication network can be performed in the process of a system (such as a base station) that controls the wireless network to control the network and transmit data, or can be performed in a user equipment.

[0073] Obviously, in a network including a base station and multiple network nodes, various operations performed for communicating with a UE can be performed by the base station or other network nodes other than the base station. Here, the term "base station (BS)" can be used interchangeably with other terms, such as fixed station, Node B, eNodeB (eNB), gNodeB (gNB), and access point (AP). In addition, the term "terminal" can be used interchangeably with other terms, such as user equipment (UE), mobile station (MS), mobile subscriber station (MSS), subscriber station (SS), and non-AP station (non-AP STA).

[0074] Here, a transmitting or receiving channel includes the meaning of transmitting or receiving information or a signal through the corresponding channel. For example, a transmitting control channel means transmitting control information or a signal through the control channel. Similarly, a transmitting data channel means transmitting data information or a signal through the data channel.

[0075] In the following description, although the term "New Radio (NR) system" is used to distinguish the systems according to various examples of the present disclosure from existing systems, the scope of the present disclosure is not limited thereto.

[0076] The New Radio (NR) system supports various subcarrier spacings (SCSs) by considering various scenarios, service requirements, potential system compatibilities, etc. In addition, to overcome the adverse channel environments such as high path loss, phase noise, and frequency offset that occur at high carrier frequencies, the NR system can support the transmission of physical signals / channels through multiple beams. In this way, the NR system can support various applications, such as enhanced mobile broadband (eMBB), massive machine type communication (mMTC) / ultra-massive machine type communication (uMTC), and ultra-reliable and low-latency communication (URLLC).

[0077] Here, 5G mobile communication technology can be defined by including the existing Advanced Long Term Evolution (LTE-A) system and the above-mentioned NR system. That is to say, 5G mobile communication technology can operate by considering backward compatibility with previous systems and the newly defined NR system. Therefore, subsequent 5G mobile communication can include technologies operating based on the NR system and technologies operating based on previous systems (e.g., LTE-A, LTE), but is not limited to a specific system.

[0078] First, the physical resource structure of the NR system to which the present disclosure is applied will be briefly described.

[0079] Figure 1 An example of an NR frame structure according to an example of the present invention is shown.

[0080] In NR, the basic unit in the time domain can be T c = 1 / (Δf max N f ). Here, Δf max = 480·10 3 and N f = 4096. In addition, k = T s / T c = 64 can be a constant regarding the multiple relationship between the NR time unit and the LTE time unit. In LTE, T s = 1 / (Δf ref ·N f,ref ), Δf ref = 15·10 3 and N f,ref = 2048 can be defined as the reference time unit. The constant regarding the multiple relationship between the NR time basic unit and the LTE time basic unit can be defined as k = T s / T c = 64.

[0081] Referring to Figure 1 , the time structure of the frame for downlink / uplink (DL / UL) transmission can include T f = (Δfmax N f / 100)·T s = 10 ms. Here, a single frame may include corresponding to T sf = (Δf mas N f / 1000)·T s = 1 ms of 10 sub - frames. The number of consecutive Orthogonal Frequency Division Multiplexing (OFDM) symbols per sub - frame may be In addition, each frame may be divided into two half - frames, and a half - frame may include sub - frames 0 to 4 and sub - frames 5 to 9. Here, half - frame 1 may include sub - frames 0 to 4, and half - frame 2 may include sub - frames 5 to 9.

[0082] N TA represents the Timing Advance (TA) between the downlink (DL) and the uplink (UL). Here, according to Equation 1 below, the transmission timing of the uplink transmission frame i is determined based on the downlink reception timing at the UE.

[0083] [Equation 1]

[0084] T TA = (N TA + N TA,offset )T c

[0085] N TA,offset represents the TA offset value that appears due to duplex mode differences, etc. Basically, in Frequency Division Duplexing (FDD), N TA,offset = 0. In Time Division Duplexing (TDD), N can be defined as a fixed value by considering the margin of the DL - UL switching time. For example, in TDD (Time Division Duplexing) of RF1 (Frequency Range 1) (which is a frequency below 6 GHz or lower), N TA,offset can be 39936T TA,offset or 2600T C . 39936T C = 20.327 μs and 25600T C = 13.030 μs. In addition, in FR2 (Frequency Range 2) for millimeter - wave (mmWave), N C can be 13792T TA,offset . At this time, 39936T C = 7.020 μs. C

[0086] Figure 2 Shows the NR resource structure to which the present disclosure can be applied.

[0087] Resource elements within a resource grid can be indexed based on each subcarrier spacing. Here, a single resource grid can be generated for each antenna port and each subcarrier spacing. Uplink / downlink transmission and reception can be performed based on the corresponding resource grid.

[0088] A resource block (RB) in the frequency domain is configured with 12 REs, and for every 12 REs, an index (n PRB ) of an RB can be configured. The index of the RB can be used within a specific frequency band or system bandwidth. The index of the RB can be defined as shown in Equation 2 below. Here, N RB sc represents the number of subcarriers of each RB, and k represents the subcarrier index.

[0089] [Equation 2]

[0090]

[0092] Digital parameter configurations can be configured differently to meet the various services and requirements of the NR system. For example, in the LTE / LTE-A system, one subcarrier spacing (SCS) can be supported, but in the NR system, multiple SCSs can also be supported.

[0093] The new digital parameter configurations of the NR system that support multiple SCSs can operate in frequency ranges or carriers such as 3 GHz or less, 3 GHz - 6 GHz, 6 GHz - 52.6 GHz or greater to solve the problem that a wide bandwidth cannot be obtained in frequency ranges or carriers such as 700 MHz or 2 GHz.

[0094] Table 1 below shows an example of the digital parameters supported by the NR system.

[0095] [Table 1]

[0096] μ <![CDATA[Δf = 2 μ ·15 [kHz]]]> Cyclic Prefix 0 15 Normal 1 30 Normal 2 60 Normal, Extended 3 120 Normal 4 240 Normal

[0097] Referring to Table 1 above, the digital parameter configuration can be defined based on the SCS, cyclic prefix (CP) length, and the number of OFDM symbols per time slot used in the OFDM system. The above values can be provided to the UE through the higher layer parameters DL-BWP-mu and DL-BWP-cp for the downlink, and through the higher layer parameters UL-BWP-mu and UL-BWP-cp for the uplink.

[0098] In Table 1 above, if μ = 2 and SCS = 60 kHz, then normal CP and extended CP can be applied. In other frequency bands, only normal CP can be applied.

[0099] Here, a normal time slot can be defined as a basic time unit for transmitting a single piece of data and control information in an NR system. The length of a normal time slot can basically include 14 OFDM symbols. In addition, different from a time slot, a subframe can have an absolute time length corresponding to 1 ms in the NR system and can be used as a reference time for the length of another time segment. Here, for the coexistence and backward compatibility of LTE and NR systems, the NR standard may require time segments such as LTE subframes.

[0100] For example, in LTE, data can be transmitted based on a transmission time interval (TTI) as a unit of time. A TTI can include at least one subframe unit. Here, even in LTE, a single subframe can be set to 1 ms and can include 14 OFDM symbols (or 12 OFDM symbols).

[0101] In addition, in the NR system, a non-slot can be defined. A non-slot can refer to a time slot having a number of symbols that is at least one symbol less than the number of symbols in a normal time slot. For example, in the case of providing low latency such as ultra-reliable and low-latency communication (URLLC) services, the latency can be reduced by a non-slot having a number of time slots less than that of a normal time slot. Here, the number of OFDM symbols included in a non-slot can be determined based on the frequency range. For example, a non-slot having a length of 1 OFDM symbol can be considered in a frequency range of 6 GHz or higher. As another example, the number of symbols used to define a non-slot can include at least two OFDM symbols. Here, the number range of OFDM symbols included in a non-slot can be configured to have a mini-slot length up to (normal time slot length) - 1. Here, although the number of OFDM symbols can be limited to 2, 4, or 7 as a non-slot standard, it is provided only as an example.

[0102] In addition, for example, SCS corresponding to μ = 1 and 2 can be used in an unlicensed band of 6 GHz or less, and SCS corresponding to μ = 3 and 4 can be used in an unlicensed band of more than 6 GHz. Here, for example, if μ = 4, it can be used for a synchronization signal block (SSB).

[0103] [Table 2]

[0104]

[0105] Table 2 shows the number of OFDM symbols per time slot for normal CP set by the subcarrier spacing The number of time slots per frame and the number of time slots per subframe In Table 2, these values are based on a normal time slot with 14 OFDM symbols.

[0106] [Table 3]

[0107]

[0108] In Table 3, in the case of applying an extended CP (i.e., μ = 2 and SCS = 60 kHz), the number of time slots per frame and the number of time slots per subframe of a normal time slot with 12 OFDM symbols per time slot are shown.

[0109] As described above, a single subframe can correspond to 1 ms on the time axis. Moreover, a single time slot can correspond to 14 symbols on the time axis. For example, a single time slot can correspond to 7 symbols on the time axis. Therefore, the number of time slots and the number of symbols that can be considered can be set differently within 10 ms corresponding to a single radio frame. Table 4 can show the number of time slots and the number of symbols according to each SCS. Although the SCS of 480 kHz may not be considered in Table 4, the present disclosure is not limited to such an example.

[0110] [Table 4]

[0111]

[0113] The V2X service can support a set of basic requirements for the V2X service. These requirements are basically designed with full consideration of road safety services. Here, the V2X UE can exchange autonomous state information through SL. The V2X UE can also exchange information with infrastructure nodes and / or pedestrians.

[0114] The V2X service (e.g., LTE Rel-15) can support at least one of the following: carrier aggregation in SL, high-order modulation, latency reduction, transmit (Tx) diversity, and sTTI (transmission time interval). For this purpose, new features can be applied to V2X communication. More specifically, the V2X UE can operate considering coexistence with other V2X UEs. For example, the V2X UE can use the same resource pool as other V2X UEs.

[0115] For example, by considering the usage scenarios for supporting V2X services as System Aspect (SA) 1, the technical features can be classified mainly based on the four categories represented in Table 5 below, but not limited thereto. In Table 5, "vehicle platooning" can be a technology that enables multiple vehicles to dynamically form a group and operate similarly. "Extended sensors" can be a technology that enables the exchange of data collected from sensors or video images. "Advanced driving" can be a technology that enables a vehicle to be based on semi-automated or fully automated driving. "Remote driving" can be a technology for remotely controlling a vehicle and a technology for providing applications. Based on this, further descriptions related thereto are given in Table 5 below.

[0116] [Table 5]

[0117]

[0118] In addition, SA1 can support operation in various systems (such as LTE and NR) because enhanced V2X (eV2X) supports the technology for supporting the V2X service. For example, the NR V2X system can be the first V2X system. In addition, the LTE V2X system can be the second V2X system. That is to say, the NR V2X system and the LTE V2X system can be different V2X systems.

[0119] The method for meeting the required low latency and high reliability in NR SL based on the NR V2X system is described below. However, the same or similar components can be extended and applied to the LTE V2X system, and include but are not limited to the following examples. That is to say, in the LTE V2X system, the present disclosure can be applied to the interactive part.

[0120] Here, the NR V2X capability can be not limited to basically only supporting the V2X service, and the V2X RAT to be used can be selected.

[0121] In addition, new service requirements for the public safety and commercial usage scenarios of the NR V2X service can be further considered. For example, the usage scenarios can include but are not limited to at least one of the following: more advanced V2X services, public safety services, network control interactive services (NCIS), railway clearance analysis (MONASTERYEND), energy-efficient and wide-coverage enhanced relay (REFEC), and audio-visual service production (AVPROD) certification.

[0122] Physical channels, signals, basic time slot structures, and physical resources can be configured for NR V2X. Here, the NR physical SL shared channel (NR PSSCH) can be a physical layer NR SL data channel. V2X UEs can exchange data and control information (e.g., the second SCI, CSI) through the NR PSSCH. The NR physical SL control channel (NR PSCCH) can be a physical layer NR SL control channel. The NR PSCCH is a channel for transmitting scheduling information of the NR SL data channel and control information (the first SL control information (SCI)) including the second SCI indication. That is, a V2X UE can send control information for SL data communication to another V2X UE through the PSCCH. The NR physical SL feedback channel (NR PSFCH) is a channel for transmitting physical layer NR hybrid automatic repeat request (HARQ) feedback information and HARQ-ACK feedback information corresponding to the NR SL data channel (i.e., PSSCH). A V2X UE can send data to another V2X UE and then receive HARQ feedback information of the corresponding data through the NR PSFCH. The NR SL synchronization signal / physical SL broadcast channel (SLSS / PSBCH) block is a channel block that transmits the NR SL synchronization signal and the broadcast channel in a single continuous time. Here, the SLSS / PSBCH block can be periodically transmitted based on a set of one or more block indices to support beam-based transmission in the NR band. The synchronization signal includes a primary SL synchronization signal (PSSS) and a secondary SL synchronization signal (SSSS). The synchronization signal is generated based on at least one SLSSID value. The NR physical SL broadcast channel (PSBCH) is a channel for transmitting system information required for performing V2X SL communication. The NR PSBCH is transmitted together with the SLSS and is periodically transmitted based on a set of SLS / PSBCH block indices to support beam-based transmission.

[0123] In addition, the PSCCH and PSSCH can be defined to support NR V2X. The UE can send an SCI to another UE via the PSCCH. Here, the Tx UE can send a first SCI (the 1st SCI, SCI format 1-A) to the Rx UE via the PSCCH. The 1st SCI can be used to schedule the PSSCH and the secondary SCI (the 2nd SCI) within the PSSCH, and the 1st SCI can include priority information, time / frequency resource allocation information, resource reservation information, demodulation reference signal (DMRS) pattern information, 2nd SCI format indicator information, 2nd beta-offset indicator information as a parameter for the SCI and PSSCH rate matching operation, DMRS port count information, modulation and coding scheme (MCS) information, additional MCS table indicator information (e.g., indicating one of the 64QAM, or 256QAM or URMCS LLC tables), PSFCH overhead indicator information (a parameter for the PSSCH rate matching operation with the 2nd SCI), and at least one reserved bit.

[0124] Figure 3 Fig. shows the NR SL time slot structure to which the present disclosure can be applied.

[0125] Refer to Figure 3 , a single SL time slot (SL time slot) includes a single automatic gain control (AGC) symbol. Moreover, a single SL time slot includes a single Tx-Rx switching symbol. In a single SL time slot, the PSSCH is the channel through which data is sent, and it is sent through at least one subchannel (e.g., Figure 3 two subchannels in). In addition, in the time domain, the PSCCH (the 1st SCI), the 2nd SCI, the PSSCH (data), and the demodulation RS (DMRS) for demodulation can be sent to the remaining OFDM symbols except for the AGC symbol and the Tx-Rx switching symbol. Specifically, the positions of the PSCCH (the 1st SCI), the 2nd SCI, the PSSCH (data), and the DMRS for demodulation can be the same as those in Figure 3 , but not limited thereto. For example, in Figure 3 , the PSCCH and the 2nd SCI are present in the first subchannel, and in consideration of this, the PSSCH and the DMRS can be allocated. As another example, the second subchannel refers to the subchannel in which the PSCCH and the 2nd SCI do not exist, and the PSSCH and the DMRS can be allocated as in Figure 3 .

[0126] Here, the number of PSSCH DMRSs can be configured according to a higher layer configuration, and one or more PSSCH DMRSs can be configured according to the UE's channel environment. The PSCCH (first SCI) uses the DMRS of the PSCCH (i.e., PSCCH DMRS) to receive demodulation, and is evenly allocated and transmitted every four resource elements (REs) within a single resource block (RB). In contrast, the PSSCH DMRS is used to decode the second SCI.

[0127] In addition, for example, a single resource pool associated with NR SL can support frequency division multiplexing (FDM), time division multiplexing (TDM), and space division multiplexing (SDM). This means that each resource in the single resource pool can be divided and used based on frequency, time, and space, which can improve resource efficiency.

[0128] Figure 4 The NR SL frequencies to which the present disclosure can be applied are shown. For example, NR SL can operate based on at least one of the following: frequency range 1 (FR1) (below 6 GHz) and frequency range 2 (FR2) (i.e., up to 52.6 GHz), unlicensed ITS bands, and licensed bands. Specifically, for example, referring to Figure 4 , 5,855 to 5,925 MHz can be allocated for ITS services (in a technology-neutral manner).

[0129] In addition, the NR V2X quality of service (QoS) requirements can be considered. That is, latency, reliability, and data rate may need to be satisfied through predetermined conditions related to the requirements of the NR V2X service. Here, these requirements can be configured as shown in Table 6 below, and Table 7 can show the PC5 QoS for NR V2X.

[0130] Here, in order to meet the QoS requirements, access stratum (AS)-level QoS management may be required. For this purpose, HARQ and CSI feedback associated with link adaptation may be required. In addition, each of the NR V2X UEs may have a different maximum bandwidth capability (maximum BW capability). Considering this, AS-level information can be exchanged between NR V2X UEs, and the AS-level information includes at least one of the following: UE capability, QoS-related information, radio bearer configuration, and physical layer configuration.

[0131] [Table 6]

[0132]

[0133] [Table 7]

[0134] · Note 1: For the standardized PQI to QoS characteristic mapping, this table can be extended / updated to support the service requirements of other identified V2X services. · Note 2: PQI can be used for services other than V2X.

[0136] In the following, the SL HARQ process is described. Whether the V2X UE is to report HARQ feedback is configured by a higher layer (e.g., RRC) and indicated by SCI signaling (e.g., the second SCI). For example, when the V2X UE performs SL communication based on multicast, it can be determined whether to report HARQ feedback based on the distance between the Tx UE and the Rx UE.

[0137] When the V2X UE performs at least one of unicast and multicast transmissions, the SL HARQ feedback can be enabled or disabled. Here, it can be determined whether to enable / disable the HARQ feedback based on at least one of the channel condition (e.g., RSRP), the distance between the Tx UE and the Rx UE, and the QoS requirement.

[0138] In the case of multicast, it can be determined whether to send HARQ feedback based on the physical distance between the Tx UE and the Rx UE. Here, when performing HARQ feedback for multicast transmission via the PSSCH, the Rx UE can send a negative response only when the received PSSCH decoding fails. This can be referred to as Option 1 operation. In addition, when performing HARQ feedback for multicast transmission via the PSSCH, the Rx UE can feedback a positive response or a negative response based on whether the PSSCH decoding is successful, and this can be referred to as Option 2 operation. In Option 1 operation where only a negative response is fed back as the only NACK HARQ feedback, if the physical distance between the Tx UE and the Rx UE is less than or equal to the communication range requirement, the HARQ feedback corresponding to the PSSCH reception can be performed. On the contrary, if the physical distance between the Tx UE and the Rx UE is greater than the communication range requirement, the V2X UE may not perform the HARQ feedback corresponding to the PSSCH reception.

[0139] Here, the position of the Tx UE is indicated to the Rx UE through the SCI signaling associated with the PSSCH. The Rx UE can estimate the distance to the Tx UE based on both the information segment included in the received SCI and its position information, and can operate as described above.

[0140] In addition, when performing unicast communication based on V2X, the case of enabling the SL HARQ feedback can be considered. The Rx UE can generate and send the HARQ ACK / NACK corresponding to the PSSCH according to whether the decoding of the corresponding transport block (TB) is successful.

[0141] Then, the NR SL resource allocation mode refers to the mode in which the base station schedules the SL transmission resources. Here, the mode in which the base station schedules the SL transmission resources can be Mode 1. For example, when the V2X UE is within the coverage area of the base station, the V2X UE can receive SL resource information from the base station. On the contrary, there is a mode in which the V2X UE directly determines the resources for SL transmission on the SL resources configured by the base station / network or pre-configured SL resources. Here, the mode in which the UE directly determines the SL transmission resources can be Mode 2.

[0142] In addition, digital parameter configuration and waveforms for the sidelink can be considered, which can be as shown in Table 8 below. Specifically, regarding PSSCH / PSCCH and PSFCH in the sidelink, the SCS and CP lengths supported in each of FR1 and FR2 can be as shown in Table 8 below. Here, the waveform can support only OFDM and not DFT-S-OFDM, but it is not limited thereto. A sidelink synchronization signal block (SL-SSB) can be defined independently for each frequency range, which can be similar to NR-Uu.

[0143] [Table 8]

[0144]

[0146] Figure 5 Illustrates the NR sidelink (SL) resource pool configuration. Refer to Figure 5 , the resource pool can represent the resources in time and frequency for sidelink transmission and reception. For example, at least one resource pool can be configured within a single SLBWP within a single carrier. Here, the resources of the resource pool can be configured based on the time resources of the time slot set unit and the frequency resources of the continuous subchannel set unit. In addition, the resource pool can be configured for each of transmission and reception.

[0147] More specifically, as the time resources provided for resource pool configuration in the NR sidelink, at least one of the following can be configured: resource pool period, sidelink time slot set within a single resource pool application period (sl-TimeResource (length = L bitmap), and the first symbol and the number of consecutive symbols in a consecutive symbol set within a single time slot. As frequency resources, at least one of the following can be configured: the bandwidth of at least one subchannel (e.g., sl-SubchannelSize = {10, 15, 20, 25, 50, 75, and 100} RBs), the entire bandwidth of a resource pool indicated by the number of consecutive subchannels (a set of consecutive subchannels (e.g., sl-NumSubchannel = {1 to 27})), and the position of the first subchannel of the resource pool in the frequency domain (sl-StartRBsubChannel = {0 to 265}). For example, the resources in the time domain and the frequency domain can be configured based on higher layer parameters. In Figure 5 If the total available RB resources do not exactly match the subchannel size (i.e., if it does not reach the number of RBs that make up a single subchannel), the frequency resources corresponding to the excluded resource blocks (RBs) can represent some remaining RBs. Here, the corresponding resources may not be used in the NR sidelink. In addition, for example, if the length of the bitmap in time resources (e.g., sl-TimeResource) is not established and cannot be used as an NR sidelink resource, the reserved time slot can indicate the remaining time slots.

[0148] Next, consider the case where an unlicensed band (unlicensed spectrum) is used for communication between the base station and the UE. For example, the communication scheme based on the unlicensed band can be a scheme of occupying a channel by competition and performing communication based on the occupied channel. Even for communication between the base station and the UE, communication based on the unlicensed band can be performed. Below, the operations in the case where the unlicensed band is used for sidelink communication are described. That is, even for sidelink communication as communication between UEs, the unlicensed band can be used. In addition, it is necessary to consider configuring the sidelink resource pool using the sidelink unlicensed band. More specifically, sidelink communication can be performed based on the resource pool. In the case of performing communication through the unlicensed band, the resource pool configuration needs to be configured differently.

[0149] For example, the sidelink communication resource pool can be configured based on time slot units, and the symbols for the sidelink within a single time slot can be determined, which is the same as Figure 5 shown. In addition, as described above in connection with Figure 5 In the frequency domain, it can be configured based on the number of consecutive subchannels. The above sidelink resource pool configuration can be configured considering unlicensed band communication, which will be described below.

[0150] Figure 6The unlicensed band of each area of NR sidelink communication to which the present disclosure can be applied is shown. In Table 8 above, the frequency range of NR FR1 can be from 450 MHz to 6 GHz, but the corresponding frequency range can vary from 450 MHz to 7.125 GHz. The frequency range of NR FR1 can be changed for the unlicensed band of the 6 GHz band, but is not limited thereto.

[0151] For example, the unlicensed band can be located below 1 GHz, 2.4 GHz, 5 GHz, 6 GHz, 37 GHz (only in the United States), and 60 GHz, but is not limited thereto. Here, referring to Figure 6 , for example, in a system, the 5 GHz band can be Band 46 defined as 5150 to 5925 MHz. In addition, for example, for LAA operation, Band 49 (3550 - 3700 MHz) can be defined as Citizen Broadband Radio Service (CBRS), but is not limited thereto.

[0152] Figure 7 The use of the 5 GHz unlicensed band to which the present disclosure can be applied is shown. Referring to Figure 7 , each band within the 5 GHz unlicensed band can be set, and based on this, the use of the unlicensed band can be set. For example, it can be divided into 20 MHz units, and each 20 MHz can be a single channel.

[0153] Here, in most areas, the low - frequency band from 5150 to 5350 MHz within the above - mentioned band is specified to have a maximum transmit power of 23 dBm for indoor use. Moreover, in the band of 5470 MHz or higher, it is used in areas with a transmit power up to 30 dBm and is used outdoors in most areas. Here, for example, there may be additional requirements in some areas, given as the Effective Isotropic Radiated Power (EIRP) value based on Table 9 below, and the maximum transmit power is restricted.

[0154] [Table 9]

[0155]

[0157] Here, the Power Spectral Density (PSD) can indicate that the device is limited to perform full - power transmission within the reference bandwidth. As a detailed example, European regulations may limit the PSD to 10 dBm / MHz. Therefore, in a non - 20 MHz bandwidth, the device may not perform transmission at the maximum transmit power of 23 dBm.

[0158] Figure 8 The method of increasing the bandwidth considering the PSD limit to which the present disclosure can be applied is shown. For example, as Figure 8As shown, it is possible to consider the case of small data transmission that only requires a small bandwidth. Here, in the case of performing small data transmission through a wide bandwidth, the coverage range can be extended. In addition, the minimum bandwidth occupancy control can be satisfied by means of transmission using a wide bandwidth. Considering this, for small data, a method of performing transmission in a wide bandwidth may be preferable.

[0159] In addition, for example, in the case of occupying a channel through a channel access procedure in an unlicensed band, the maximum channel occupancy time (COT) corresponding to the maximum allowable occupancy time can be set differently for each region. For example, Japan allows a maximum COT of up to 4 ms, while Europe allows a maximum COT of up to 8 ms or 10 ms. However, this is merely an example and is not limited to the above embodiments. In addition, for example, Europe can support Frame-based Equipment (FBE) and Load-based Equipment (LBE) rules. Here, FBE can be set to High Performance Radio (LAN HiperLAN) / 2, and LBE can be adopted and applied according to the Wi-Fi standard specification, and both can be supported in NR, which is a new communication system.

[0160] In addition, for example, the minimum occupancy bandwidth can be the bandwidth control that needs to be minimally occupied when the channel access is successful once. For example, the minimum occupancy bandwidth control can be configured to occupy 80% to 90% or more of the nominal channel BW. As a detailed example, when a UE sends a PUSCH to a base station in an unlicensed band, it can request to allocate resources for the PUSCH in an interleaved form in a specific bandwidth, but it is not limited to the corresponding embodiments.

[0161] In addition, the control regarding dynamic frequency selection can be a control that restricts bandwidth use for the purpose of protecting a system (such as a radio) with a high priority for using an unlicensed band. In addition, the transmit power control regulation can be a regulation that limits the transmit power to be much lower than the maximum transmit power value allowed for use. In addition, the Listen Before Talk (LBT) regulation can be a regulation for the channel access procedure, and Europe can support FBE and LBE rules. Here, FBE can be Hiperlan / 2, and LBE can be adopted and applied from the Wi-Fi standard specification, and both can be supported in NR.

[0162] In addition, for example, based on the above description, the 5 GHz unlicensed band can be used, but the use of the 6 GHz band is being discussed in each country and organization. Here, the 6 GHz band can be a band that is different from the 5 GHz band and is not used in mobile systems. That is, different from the 5 GHz band shared by multiple mobile communication systems, the 6 GHz band can be used for a single specified communication system. Therefore, problems or inefficiencies caused by the coexistence of different systems can be reduced.

[0163] Figure 9 Shows a method for configuring guard bands in consideration of a shared frequency band (e.g., unlicensed frequency band) within a cell to which the present disclosure can be applied.

[0164] Referring to Figure 9 , to support broadband operations in shared spectrum access, a UE can receive an IntraCellGuardBandsPerSCS parameter for each of the UL carrier and the DL carrier from a base station based on the base station configuration. N RB-set,x -1 in-cell guard bands can be provided for the UE in a single carrier (subcarrier spacing index = μ). Referring to Figure 9 , the UE can receive higher layer signaling for: the number of common resource blocks (CRBs) and the starting CRB for each guard band. For example, a CRB can be a resource block defined / configured based on point A, which is the starting position of the transmission bandwidth in a carrier in the frequency domain. The UE can verify information about point A through base station signaling, and based on this, can identify the CRB position in the frequency. Here, each guard band can be defined as the starting CRB based on the parameter, and within each guard band, the size of the number of CRBs can be defined based on the parameter. The UE can receive the aforementioned information through higher layer signaling based on each of the startCRB and nrofCRB parameters. Here, s ∈ {0, 1, …, N RB-set,x -2}, N RB-set,x represents the number of RB sets, and x can be configured for DL or UL for downlink and uplink. N RB-set,x RB sets can be configured as a resource block set (RBS) within a single carrier through guard band configuration. For example, the guard bands can be configured based on the IntraCellGuardBandsPerSCS parameter, and the RBS can be configured accordingly within a single carrier.

[0165] Here, the frequency bandwidth of each RBS can correspond to an LBT frequency bandwidth. That is, each RBS can be set to a bandwidth corresponding to the LBT process performed by the base station and the UE. For example, in Figure 9In [the above scenario], if LBT is successful in the corresponding region corresponding to the LBT bandwidth, RB set 1 911 and RB set 2 912 can occupy the corresponding frequency band and can perform communication. That is to say, the RBS can correspond to the LBT bandwidth. For example, a Tx node (e.g., a gNB or a UE) can determine the channel occupancy of the unlicensed frequency band through an LBT channel access procedure performed on the RBS resources corresponding to the LTE bandwidth. When the LBT process is successful in a single RBS, the Tx node can perform transmission on the resources corresponding to that RBS.

[0166] Here, each RBS can be defined by a starting CRB and an ending CRB. The starting CRB can be The ending CRB can be Here, the size of the guard band 913 can be nrofCRB. For example, according to the subcarrier spacing μ and the carrier size It may not be desirable to set the size nrofCRB of the guard band 913 to be less than the size of the applicable intra-cell guard band defined considering the interference status regarding the radio bandwidth requirements.

[0167] Here, the starting CRB and the ending CRB of each RBS (911, 912) can be determined based on the RBS index, and the RBS index can be s ∈ {0, 1, …, N RB-set,x -1}. That is to say, the RBS index s can be a resource block with size, and represents the number of CRBs determined by the starting CRB and the ending CRB based on Equation 3 below. Moreover, in each RBS, the starting CRB and the ending CRB can be as shown in Equation 4 and Equation 5 below.

[0168] [Equation 3]

[0169]

[0170] [Equation 4]

[0171]

[0172] [Equation 5]

[0173]

[0175] For example, if the UE is not configured with the IntraCellGuardBandsPerSCS parameter, the carrier μ and the carrier size can be determined according to the requirements of the RF standard The nominal in-cell guard band and the CRB index of the RBS mode. Additionally, for example, if the above nominal in-cell guard band and RBS mode do not include an in-cell guard band, the RBS of the corresponding carrier can be assumed to be 1.

[0176] For example, in Figure 9 , two LBT BWs (RBS 0, RBS1) can be configured in a single BWP922 within the single carrier bandwidth. Here, a single guard band 913 can be configured between the two RBSs 911 and 913. The position of each of the two RBSs 911 and 913 can be determined based on the above higher layer parameters as shown in Figure 9 . Additionally, for example, when multiple BWPs 921 and 923 are configured within the single carrier bandwidth, the RBSs associated with each BWP can be verified. Here, the RBSs corresponding to the first RBS (= s0, 912) and the last RBS (= s1, 911) of each BWP among the RBSs 911 and 912 within the carrier can be indexed by the s0 and s1 indices.

[0178] Figure 10 shows an unlicensed band applicable to the present disclosure. Referring to Figure 10 , the NR-U band as an unlicensed band (e.g., NR) of a wireless communication system can include two frequency ranges: a low frequency band of 7 GHz or less and a high frequency band of 60 GHz. However, this is merely an example and can be not limited thereto. For example, in Figure 10 , a 2.4 GHz band can be used for Industrial, Scientific and Medical (ISM), a 3.5 GHz band can be used for Citizen Broadband Radio Service (CBRS), and a band from 5 GHz to 6 GHz can be used for Unlicensed National Information Infrastructure (UNII). The UNII (5.925 GHz to 7.125 GHz) band can include multiple bands (UNII-1, UNII-2, …, UNII-8). For each of the multiple bands (UNII-1, UNII-2, …, UNII-8) within the UNII, different transmission powers, indoor / outdoor operations, maximum effective isotropic radiated power (EIRP), and dynamic frequency selection (DFS) requirements can be determined, but it can be not limited to a specific form.

[0179] The frequency band from 5 GHz to 6 GHz can be divided into non - overlapping 20 - MHz channel bandwidths. Here, channels with wide bandwidths such as 40 MHz, 80 MHz, and 160 MHz can be configured based on the boundaries. For example, a part of the 6 - GHz frequency band can coexist with systems using backhaul communication (UNII - 5, UNII - 7), satellite (UNII - 5), broadcast (UNII - 6, UNII - 8), and ultra - wideband (UWB) systems (UNII - 6). The number of channels in the UNII - 5 band (5.925 to 6.425 GHz) can be 24, 12, 6, and 4 at 20 MHz, 40 MHz, 80 MHz, and 160 MHz respectively. In addition, the UNII - 5 band (5.925 to 6.425 GHz) can be used outside indoor and protected areas. Here, indoor can be determined as EIRP 30 dBm (AP) and 24 dBm (UE), and outdoor can be determined as EIRP 36 dBm (AP) and 30 dBm (UE), but they are not limited to a specific form.

[0180] The channels described below can be part of a single carrier or multiple consecutive resource blocks (RBs) within the carrier. For example, the channel access process can be a process of verifying the channel based on sensing to perform transmission. In the case of performing the channel access process, the base station or UE can perform energy detection based on a time - slot unit, and if it is less than or equal to a preset value, it can determine that the channel is in an idle state. Hereinafter, a method of operating in an unlicensed frequency band based on the above operations is described.

[0181] Figure 11 A sidelink resource pool to which the present disclosure can be applied is shown. Refer to Figure 11 , multiple Tx resource pools (RPs) and Rx RPs can be configured for the UE. The resource pool can be identified by an identifier / identification (ID), and added to or removed from the UE. In addition, for example, each resource - pool configuration can be different. Specifically, the PSCCH, PSSCH, and PSFCH configurations of the resource pool can be different for each resource pool. In addition, the resource pool can be configured with the starting position of sub - channels within a sidelink bandwidth part (SL BWP) (which indicates the resource position), the number of RBs, and the sub - channel size according to frequency. In addition, in the resource pool, the position of time resources can be configured in a bitmap format. Here, except for the time slots used in the SSB and uplink, time resources can be mapped, and the time resources can be repeatedly applied for each bit configured within a system frame number (SFN).

[0182] Specifically, for example, refer to Figure 11, the UE can determine the resource locations in a specific resource pool within the SL BWP. The subchannel size can represent a physical resource block (PRB) as the minimum unit for selecting resources. Moreover, "SL-startRBsubchannelSize" can represent the starting RB of the subchannel within the SL BWP, "SL-RB-number" can represent the number of available RBs within the SL BWP, and "SL-SubchannelSize" can represent the size of a single subchannel. The UE can determine the number of subchannels to be used within the SL BWP based on the above parameters. In addition, for example, the time-axis resources can be indicated in units of time slots by "sl-TimeResource". Specifically, for example, when the UE receives the indication of "0011111100" as a 10-bit indicator, the UE can use the resources of the time slots indicated by 1, which does not include the time slots containing the reserved time slot SSB. In addition, the UE can not use the time slots not included in the above subchannel RBs within the SL BWP, or the time slots indicated by 0 in "SL-TimeResource". For example, up to 4 SL BWPs can also be configured, and one of the configured BWPs can be activated and used. Moreover, within the SL BWP, up to eight Tx resource pools can be configured, and up to 16 Rx resource pools can be configured, which is not limited to a specific embodiment.

[0183] Sidelink communication can be performed based on the above in the unlicensed band, and based on this, the LBT operation can be performed. That is, the UE can verify whether the channel is being used before transmitting a signal in the unlicensed band, and if it is verified that the channel is in an idle state, the UE can transmit the signal. For example, the method for the UE to select transmission (or retransmission) resources from the resource pool is described below.

[0184] For example, the UE can perform transmission through the sidelink shared channel (SL-SCH). Specifically, the UE can receive the sidelink authorization through at least one of the physical downlink control channel (PDCCH) and radio resource control (RRC). When the UE receives the PDCCH scrambled with the scheduling-radio network temporary identifier (SLC-RNTI) configured for the sidelink and in which the new data indicator (NDI) indicates 1, the UE can determine that it has received a dynamic sidelink authorization and can perform based on this. For example, the SLCS-RNTI can be an identifier indicating the configured scheduling of sidelink communication, and if the UE receives the DCI scrambled with the SLCS-RNTI, the UE can perform sidelink communication based on the pre-configured scheduling. As another example, the UE can automatically generate the sidelink authorization in the MAC layer of the UE. That is, the MAC layer of the UE can have the sidelink authorization to determine the PSCCH and PSSCH durations within the activated SL BWP.

[0185] Specifically, for example, when the sidelink resource allocation mode 1 is configured for the UE, the UE can perform operations based on the authorization received in the PDCCH occasion. For example, the sidelink resource assignment mode 1 can be a mode in which the base station schedules the sidelink resources. The base station can schedule the sidelink resources for the UE through the DCI of the PDCCH, and the UE can perform sidelink communication with another UE through the resources indicated by the base station. For example, the UE can receive the DCI scrambled with the SL-RNTI. Here, the NDI included in the DCI may not be toggled, and if the NDI is not toggled, it can indicate retransmission. If the NDI included in the DCI is not toggled, the UE can determine the PSCCH and PSSCH durations during which at least one retransmission related to a single MAC protocol data unit (PDU) will be performed through the received sidelink authorization.

[0186] On the other hand, if the NDI included in the DCI is toggled (i.e., in the case of performing a new transmission), the UE can determine the PSCCH and PSSCH durations during which the transmission related to a single MAC PDU is performed through the received sidelink authorization. In addition, if retransmission resources are configured for the UE, the UE can also determine the resources for performing the retransmission of a single MAC PDU. For example, when the UE receives a retransmission sidelink authorization for the MAC PDU for which it has received an ACK, the UE can remove the PSCCH and PSSCH durations configured to perform the retransmission of the MAC PDU.

[0187] As another example, the UE may receive DCI scrambled with the SLCS-RNTI. Here, when the configured sidelink grant (CG) activated by the DCI indicates a retransmission of a specific HARQ process ID, the UE may determine the PSCCH and PSSCH durations for a single MAC PDU transmission. As another example, when the DCI indicates deactivation for type 2 CG, the UE may generate a sidelink grant confirmation for the configured sidelink grant. Specifically, the UE may generate a sidelink grant confirmation MAC CE. On the other hand, when the DCI indicates activation for type 2 CG, the UE may generate a confirmation for the configured sidelink grant and may determine the PSCCH and PSSCH durations for multiple MAC PDU transmissions. For example, type 1 CG may be a CG type where the UE receives a grant via RRC and performs transmission via the scheduled resources without DCI or other triggers. On the other hand, type 2 CG may be a CG type where, if the UE receives a grant via RRC and then triggers the corresponding grant-based transmission via DCI, the UE activates the CG and performs the transmission.

[0188] Figure 12 A method for a UE operating based on sidelink resource assignment mode 2 applicable to the present disclosure is shown. For example, sidelink resource assignment mode 2 may be a mode in which the UE directly determines resources for performing sidelink communication by sensing. Referring to Figure 12 , the UE may generate sidelink resources (S1201). Specifically, the MAC layer of the UE may select resources within a resource pool based on sensing and random selection within the sidelink carrier. For example, if a sidelink grant is received from the MAC layer of the UE, the physical layer of the UE may perform operations based on this sidelink grant. In addition, for example, the MAC layer of the UE may configure at least one logical channel (LCH), and the UE may perform retransmissions. When "sl-HARQ-FeedbackEnabled" is set to "enabled" in at least one of the LCHs configured for the UE, the UE may determine that the PSFCH is configured in at least one resource pool.

[0189] Referring to Figure 12, the UE may generate a sidelink grant (S1201). Here, the UE may determine whether to configure multiple MAC PDUs based on how much data is included in the LCH. For example, the UE may generate a sidelink grant for multiple MAC PDU transmissions as a case where there is data in a specific LCH (S1202). Here, the UE may select a resource pool according to whether "sl-HARQ-FeedbackEnabled" of the corresponding LCH is enabled (S1203). For example, when "sl-HARQ-FeedbackEnabled" of the corresponding LCH is set to "enabled", the UE may select one of the resource pools in which the PSFCH is configured as the resource pool among the configured resource pools (S1204). On the other hand, when "sl-HARQ-FeedbackEnabled" of the LCH is set to "disable", the UE may select a single resource pool regardless of whether the PSFCH is configured in the configured resource pool (S1204). Then, the UE may perform resource selection (or reselection) in the selected resource pool (S1205). In addition, the UE may deliver the sidelink grant to the HARQ entity (S1206). For example, the UE may continuously perform a transmission resource selection (or reselection) check operation until the UE determines to cancel the sidelink grant generation corresponding to multiple MAC PDU transmissions, or until the RRC releases the corresponding resource pool. For example, when the UE performs transmission resource reselection based on the transmission resource selection (or reselection) operation, the UE may select an available value within the "SL-ResourceReservePeriodList" configured by the RRC as the resource reservation interval P RVSP_TX . The UE may select a value within the "SL-ResourceReservePeriodList" that is greater than the remaining packet delay budget (PDB) of the sidelink data as the resource reservation interval P RVSP_TX . For example, in each resource pool, the "SL-ResourceReservePeriodList" may have up to 16 reservation interval values. The reservation interval values may indicate values of 0, 1 to 99, 100, 200, 300, 400, and 1000 ms, but are not limited thereto. If the selected resource reservation interval P RVSP_TX is greater than or equal to 100 ms, the UE may randomly select a value between [5, 15] and set it as the sidelink resource reselection counter (SL_RESOURCE_RESELECTION_COUNTER). On the other hand, if the resource reservation interval P RVSP_TX is less than 100 ms, the UE may be in A value is randomly selected therebetween and can be set to the sidelink resource reselection counter (SL_RESOURCE_RESELECTION_COUNTER).

[0190] In addition, the UE can select the number of HARQ retransmissions and frequency resources within the values configured as RRC parameters. The UE can randomly select the time and frequency resources for one transmission opportunity from the resources indicated by the physical layer according to the remaining PDB of the sidelink data in the LCH and the amount of the selected frequency resources. For example, the UE can use the randomly selected resources to select the periodic resources located by the resource reservation interval P RVSP_TX Furthermore, when the UE selects at least one HARQ retransmission, if resources indicated by the physical layer remain, the MAC layer of the UE can randomly select resources considering the minimum time gap of the PSFCH with the resource pool, the remaining PDB of the sidelink data, and the number of HARQ retransmissions. The UE can use the randomly selected resources to select the periodic resources located by the resource reservation interval P RVSP_TX Here, the UE can determine the first transmission as the initial transmission and can determine subsequent transmissions as retransmissions in the resources periodically configured at each resource reservation interval P RVSP_TX

[0191] In addition, for example, when the UE generates a sidelink grant for a single MAC PDU transmission as the case where data exists in a specific LCH (S1203), the UE can select a resource pool (S1203) according to whether "sl-HARQ-FeedbackEnabled" of the corresponding LCH is enabled. That is, when "sl-HARQ-FeedbackEnabled" of the LCH is set to "enabled", the UE can select one of the resource pools in which the PSFCH is configured within the configured resource pool. On the other hand, when "sl-HARQ-FeedbackEnabled" of the LCH is set to "disabled", the UE can select a single resource pool regardless of whether the PSFCH is configured within the configured resource pool.

[0192] ​As another example, when the UE performs sidelink channel state information (CSI) reporting in a situation where data exists in a specific LCH, the UE can select a resource pool according to whether "sl-HARQ-FeedBackEnabled" of the LCH is enabled. When "sl-HARQ-FeedBackEnabled" of the LCH is set to "enabled", the UE can select one of the resource pools in which the PSFCH is configured within the configured resource pool. On the other hand, when "sl-HARQ-FeedBackEnabled" of the LCH is set to "disabled", the UE can select a resource pool regardless of whether the PSFCH is configured within the configured resource pool. Here, "SL-HARQ-FeedbackEnabled" can be included in the "SL-LogicalChannelConfig IE" and can be as shown in Table 10 below, but is not limited thereto.

[0193] [Table 10]

[0194] sl-HARQ-FeedbackEnabled ENUMERATED{enabled,disabled}

[0196] Then, the UE can perform resource selection (or reselection) in the selected resource pool (S1205). In addition, the UE can deliver the sidelink grant to the HARQ entity (S1206). For example, the UE can continuously perform the transmission resource selection (or reselection) check operation until the UE determines to cancel the sidelink grant generation corresponding to a single MAC PDU transmission, or until the RRC releases the corresponding resource pool. The UE can select the HARQ retransmission number and frequency resources within the value configured to the RRC parameter. In addition, the UE can randomly select the time and frequency resources for one transmission opportunity from the resources indicated by the physical layer according to the remaining PDB of the sidelink data in the LCH, the amount of the selected frequency resources, and the latency requirement of the SL-CSI. In addition, when at least one HARQ retransmission is selected, if resources indicated by the physical layer of the UE remain, the MAC layer of the UE can randomly select resources considering the minimum time gap with the PSFCH of the resource pool, the remaining PDB of the sidelink data, and the number of HARQ retransmissions. For example, when the transmission resources cannot be selected according to the resources assigned by the previous SCI, the UE can select the retransmission resources in a different manner, but it is not limited to a specific form.

[0197] Figure 13 shows an operation method of the sidelink HARQ entity applicable to the present disclosure, and Figure 14 shows a sidelink procedure applicable to the present disclosure. Refer to Figure 13, the sidelink HARQ entity may receive a sidelink grant from the MAC entity (S1301). For example, the MAC entity of the UE may perform resource pool selection and resource selection. The sidelink HARQ entity may perform MAC PDU acquisition and transmission determination as well as sidelink transmission information determination. Additionally, the sidelink procedure may represent an indication of transmission to the physical layer. Here, each of the MAC entity and the HARQ entity may be a different entity, but they may be logically distinct entities and may not be limited to a specific form. In the following, for the sake of clear description, the description is made based on the operations performed by each of the MAC entity and the HARQ entity. However, it may not be limited thereto.

[0198] For example, the sidelink HARQ entity may verify whether the sidelink grant is for an initial transmission (S1302). When the sidelink grant is for an initial transmission (S1303), the sidelink HARQ entity may verify the associated sidelink procedure (S1304). Here, when the sidelink HARQ entity does not obtain the MAC PDU from the multiplexing and assembly entity (S1305), the sidelink HARQ entity may refresh the HARQ buffer of the associated sidelink procedure (S1306). For example, if the sidelink HARQ entity selects a resource pool due to the generation of a sidelink grant in the MAC entity, but the MAC PDU is not delivered from the multiplexing and assembly entity, the UE may ignore the generated sidelink grant. For example, the UE may perform the above operations for periodic resource configuration considering subsequently generated MAC PDUs, but it is not limited thereto.

[0199] On the other hand, when the sidelink HARQ entity obtains the MAC PDU from the multiplexing and assembly entity (S1305), the sidelink HARQ entity may determine the sidelink transmission information (S1307). Then, the sidelink HARQ entity may deliver the MAC PDU, the sidelink grant, and the sidelink transmission information to the sidelink procedure (S1308). Then, the sidelink HARQ entity may instruct the associated sidelink procedure to trigger a new transmission to the MAC entity (S1309).

[0200] On the other hand, when the sidelink grant is not for an initial transmission (S1302), the sidelink HARQ entity may determine a retransmission (S1310). Here, the sidelink HARQ entity may verify the associated sidelink procedure (S1311), and may deliver the sidelink grant to the MAC entity (S1312). Then, the sidelink HARQ entity may instruct the associated sidelink procedure to trigger a new transmission to the MAC entity (S1313).

[0201] In addition, for example, referring to Figure 14, the MAC entity can receive a request from the sidelink HARQ entity (S1401). Here, when the request is an initial transmission request (S1402), the MAC entity can perform an initial transmission (S1403). In addition, the MAC entity can store the MAC PDU and the sidelink grant (S1404). Then, the MAC entity can generate a transmission (S1405). For example, the MAC entity can instruct the physical layer to send an SCI according to the sidelink transmission information. In addition, the MAC entity can instruct the physical layer to perform the above transmission, and based on this, the transmission can be performed.

[0202] On the other hand, when the request is not an initial transmission request (S1402), the MAC entity can perform a retransmission (S1406). In addition, the MAC entity can store the sidelink grant (S1407). Then, the MAC entity can generate the transmission (S1405). For example, the MAC entity can instruct the physical layer to send an SCI according to the sidelink transmission information. In addition, the MAC entity can instruct the physical layer to perform the above transmission, and based on this, the transmission can be performed.

[0203] In addition, for example, sidelink communication can be performed by considering the case of configuring a resource pool in the LBT bandwidth. Specifically, multiple LBT bandwidths (RB sets) can be configured in the wideband. Here, at least one available resource pool can be configured in each LBT bandwidth. That is, the UE can perform the LBT operation in each LBT bandwidth and may need to select a resource pool based on the LBT operation. For example, if the UE fails in the LBT, the UE can not use the corresponding LBT bandwidth and can not select the resource pool within the corresponding LBT bandwidth. Here, the physical layer of the UE can indicate the LBT failure to the MAC layer based on the LBT operation. For example, when the UE performs the sidelink reception and generation process, the MAC layer of the UE may need to perform the resource pool selection for attempting sidelink transmission by considering the LBT failure or success from the physical layer of the UE, and a method for this purpose is described below. For example, although the UE operation based on the above sidelink resource assignment mode 2 is described below, it is not limited thereto. That is, the following operations can even be applied to sidelink resource assignment mode 1 and are not limited to specific embodiments.

[0204] Figure 15 A sidelink resource pool configured in a single unlicensed band applicable to the present disclosure is shown. Refer to Figure 15 , the SL BWP can have a 20 MHz bandwidth as a single band. In addition, a resource pool can be configured within the SL BWP. Specifically, for example, refer to Figure 15In (a) thereof, resource pools 1510 and 1520 within the SL BWP can be distinguished based on the presence or absence of the PSFCH. Here, resource pools 1510 and 1520 within the SL BWP can represent the same resources on the frequency axis, but can be distinguished based on the time axis. For example, resource pools 1510 and 1520 within the SL BWP can be distinguished by the "SL-TimeResource" parameter, and the resource pool 1510 with the PSFCH and the resource pool 1520 without the PSFCH can be configured.

[0205] As another example, referring to Figure 15 In (b) thereof, the resource pool 1530 within the SL BWP can be configured with the same resources on both the time axis and the frequency axis. Here, the resource pool 1530 within the SL BWP can be distinguished by the presence or absence of the PSFCH. That is, the resource pool 1530 with the same time and frequency resources within the SL BWP can be distinguished by the presence or absence indication of the PSFCH. Here, when the MAC layer of the UE generates a sidelink grant, the MAC layer of the UE can select a resource pool according to whether the PSCFH is configured. For example, if HARQ feedback is set to enabled, the MAC layer of the UE can select the resource pool 2 in which the PSFCH is configured. On the other hand, if HARQ feedback is set to "disabled", the MAC layer of the UE can select a resource pool regardless of whether the PSFCH is configured. Therefore, the UE can select one resource pool between resource pool 1 and resource pool 2. Here, for example, if LBT fails a preset number of times or more in the SL BWP of the unlicensed band, the UE can perform an LBT failure recovery operation. Specifically, the UE can perform a BWP switch to the LBT failure recovery operation. However, as Figure 15 shown, when the UE operates in a single unlicensed band, the UE can not perform a BWP switch to the LBT failure recovery operation, and can request an LBT failure operation.

[0206] In addition, for example, Figure 16 shows an SL BWP configuration operating in the wideband. Referring to Figure 16 , the SL BWP can have a 40 MHz bandwidth same as the wideband. However, this is only an example and is not limited thereto. Resource pools can be configured within the SL BWP. For example, referring to Figure 16 In (a) thereof, resource pools 1610, 1620, 1630, 1640, 1650 can be configured and indicated for each LBT bandwidth (or RB set) within the 40 MHz SL BWP. Here, the presence or absence of the PSFCH can be configured differently for each of the resource pools 1610, 1620, 1630, 1640, 1650. As another example, referring to Figure 16In (b) thereof, the resource pool 1660 can be configured across two LBT bandwidths (or RB sets) and is not limited to a specific form.

[0207] In addition, for example, the resource pool can be configured differently for each quality of service (QoS) in a specific sidelink communication (e.g., Rel-12 ProSe sidelink). Thus, a specific resource pool can be used in a specific QoS. On the other hand, the resource pool can support all QoS levels allowed in other sidelink communications (e.g., LTE V2X sidelink, NR V2X sidelink). That is, a specific service type that meets the QoS can be satisfied in any resource pool regardless of the resource pool selection. With this in mind, one or more resource pools can be configured within the SL BWP, and multiple resource pools are not necessary. In addition, for example, a service type that requires a specific QoS based on a higher layer configuration in other sidelink communications (e.g., LTE V2X sidelink, NR V2X sidelink) can be associated with at least one carrier frequency.

[0208] In addition, for example, in the case of selecting carriers based on carrier aggregation operations in other sidelink communications (e.g., LTE V2X sidelink, NR V2X sidelink), multiple carriers can be selected as candidate carriers based on the per-packet priority of neighboring services (PPPP). Here, the finally selected carrier can be determined as the carrier with the lowest CBR among the candidate carriers. That is, the finally selected carrier can be determined as the carrier with the lowest resource occupancy rate in the resource pool among the candidate carriers, and thus high QoS can be provided.

[0209] Refer to Figure 16 , in the LBT process in unlicensed broadband operation, the LBT process can be performed in units of LBT bandwidth (or RB set). Here, at least one resource pool can be configured in the LBT bandwidth (or RB set). For example, the UE may not be able to identify which LBT bandwidth the LBT will be successful for. Thus, the resource pool can be configured to be set and selected in each LBT bandwidth. For example, since non-3GPP (e.g., Wi-Fi, etc.) access coexists in the unlicensed band, the channel state can be different for each LBT bandwidth.

[0210] Here, referring to Table 11 below which is an existing communication system, the UE can perform resource pool selection without considering sidelink unlicensed band operation and only considering the "sl-HARQ-FeedBackEnabled" parameter. However, when the UE performs resource pool selection based on the sidelink unlicensed band, the UE may need to perform resource pool selection by considering whether LBT fails. Specifically, when the UE selects a resource pool within the RB set where LBT fails, the UE may not occupy the channel, which makes it impossible to send PSCCH and PSSCH.

[0211] [Table 11]

[0212]

[0214] For example, in Figure 16 (b), when the UE has successful LBT only in RB set 0, the UE may not select resource pool 01660 and resource pool 2 1680. That is, the UE may not select the resource pool within the RB set where LBT fails and may request an operation based on this. Therefore, when the UE performs resource pool selection, the UE can consider the content in Table 12 below. Specifically, the UE can perform resource pool selection based on the LBT result, and the related description is given below. As another example, the UE can perform resource pool selection based on the LBT failure counter, and the related description is given below. As another example, the UE can consider CBR to perform RB set and resource pool set selection, and the related description is given below. As another example, the UE can perform resource pool selection by considering both the LBT failure counter and CBR, and the related description is given below. That is, the UE can consider the LBT result and CBR to select the resource pool.

[0215] [Table 12]

[0216]

[0218] For example, when the MAC layer of the UE generates a sidelink grant, the MAC layer of the UE can consider the LBT result or the LBT failure counter for each LBT bandwidth (or RB set) configured in the SL BWP to select the resource pool. Specifically, Figure 17 illustrates the resource pool selection process applicable to the present disclosure. Refer to Figure 17When generating LCH data that requires HARQ feedback, the MAC layer 1710 of the UE may perform a process of generating a sidelink grant. Here, the MAC layer 1710 of the UE may instruct the physical layer 1720 of the UE to perform an LBT check to select a resource pool. The physical layer 1720 of the UE may perform an LBP operation for each LBT bandwidth (or RB set) configured within the SL BWP, and may report the LBT execution result information to the MAC layer 1710 of the UE.

[0219] Specifically, for example, when the MAC layer 1710 of the UE instructs the physical layer 1720 of the UE to perform an LBT check, the MAC layer 1710 of the UE may instruct the physical layer 1720 of the UE of the LBT bandwidth (or RB set) for which the LBT is to be performed. As another example, the MAC layer 1710 of the UE may instruct the physical layer 1720 of the UE to perform an LBT for the entire SL BWP. In addition, the LBT result report for each LBT bandwidth (or RB set) reported by the physical layer 1720 of the UE to the MAC layer 1710 of the UE may include information about the LBT bandwidth (or RB set) in which an LBT failure has occurred. As another example, the LBT result report for each LBT bandwidth (or RB set) may include information about the LBT bandwidth (or RB set) in which no LBT failure has occurred, and is not limited to a specific embodiment.

[0220] Specifically, for example, when Figure 16 the SL BWP and the resource pool are configured for the UE as shown in (a) above, data may be generated in the LCH that requires HARQ feedback in the UE. Here, the MAC layer 1710 of the UE may instruct the physical layer 1720 of the UE to perform an LBT check for the LBT bandwidth (or RB set) within the SL BWP. The physical layer 1720 of the UE may report the LBT failure status for the LBT bandwidth (or RB set) to the MAC layer 1710 of the UE. Here, if an LBT failure occurs in RB set 0, the physical layer 1720 of the UE may deliver the information about RB set 0 in which the LBT failure has occurred to the MAC layer 1710. As another example, the physical layer 1720 of the UE may deliver the information about RB set 1 in which no LBT failure has occurred to the MAC layer 1710 of the UE, and this is not limited to a specific embodiment. The MAC layer 1710 of the UE may select the resource pool 0 1610 in which the PSFCH is configured within RB set 1 based on the report from the physical layer 1710 of the UE, excluding the resource pool within RB set 0 in which an LBT failure has occurred.

[0221] In addition, for example, when HARQ feedback for a specific logical channel is activated as a case of performing resource pool selection in the MAC layer of the UE, the MAC layer of the UE may select a resource pool in which the PSFCH is configured, which includes the LBT bandwidth (or RB set) in which no LBT failure has occurred within the configured resource pool.

[0222] As another example, when HARQ feedback for a specific logical channel is activated as a case of performing resource pool selection in the MAC layer of the UE, the MAC layer of the UE may select a resource pool in which the PSFCH is configured, which includes the LBT bandwidth (or RB set) in which no LBT failure has occurred within the configured resource pool. As another example, when, as a case of performing resource pool selection in the MAC layer of the UE, a specific logical channel is generated not by sidelink data but by SL-CSI, the MAC layer of the UE may select a resource pool in which the PSFCH is configured, which includes the LBT bandwidth (or RB set) in which no LBT failure has occurred within the configured resource pool.

[0223] That is, the MAC layer of the UE may select a resource pool in which no LBT failure has occurred among all the LBT bandwidths (or RB sets) within each resource pool related to each of the multiple configured resource pools.

[0224] In addition, specifically, for example, the MAC layer of the UE may obtain the LBT result by indicating the LBT operation to the physical layer based on previous sidelink transmissions and other operations. That is, the MAC layer of the UE may continuously verify the LBT result, but it is not limited thereto. The MAC layer of the UE may select a resource pool in which no LBT failure has occurred among all the LBT bandwidths (or RB sets) within each resource pool configured based on the LBT result.

[0225] Figure 18 A method for a UE to perform resource selection considering the LBT result applicable to the present disclosure is shown. For example, the UE may operate in sidelink resource assignment mode 2, in which the UE directly determines the resources for performing sidelink communication by sensing. Refer to Figure 18 , the UE may generate sidelink resources (S1801). For example, when receiving a sidelink grant from the MAC layer of the UE, the physical layer of the UE may perform operations based thereon. The MAC layer of the UE may configure at least one LCH, and this LCH may be a unit for performing retransmission. Here, the MAC layer of the UE may indicate an LBT check for the SL BWP to the physical layer of the UE. Refer to Figure 18 , the UE may configure multiple MAC PDUs in the data existing in the LCH.

[0226] Specifically, when the UE generates a sidelink grant for multiple MAC PDU transmissions in the case where data exists in a specific LCH (S1802), the UE can select a resource pool according to whether the "sl-HARQ-FeedBackEnabled" of the corresponding LCH is enabled (S1803). For example, when the "sl-HARQ-FeedBackEnabled" of the corresponding LCH is set to "enabled", the UE can be associated with the LBT bandwidth (RB set) where no LBT failure occurs in the configured resource pool, and can select the resource pool in which the PSFCH is configured (S1804). On the other hand, when the "sl-HARQ-FeedBackEnabled" of the LCH is set to "disabled", the UE can be associated with the LBT bandwidth (RB set) where no LBT failure occurs in the configured resource pool, and can select any resource pool regardless of whether the PSFCH is configured (S1804). That is, the UE can select a resource pool by considering whether HARQ feedback is configured in the LBT bandwidth (or RB set) where LBT is successful. Then, the UE can perform resource selection (or reselection) in the selected resource pool (S1805). In addition, the UE can deliver the sidelink grant to the HARQ entity (S1806). For example, the UE can continuously perform the transmission resource selection (or reselection) check operation until the UE determines to cancel the sidelink grant generation corresponding to the multiple MAC PDU transmissions, or until the RRC releases the corresponding resource pool. For example, when the UE performs transmission resource reselection based on the transmission resource selection (or reselection) operation, the UE can select an available value within the "SL-ResourceReservePeriodList" configured by the RRC as the resource reservation interval P RVSP_TX . The UE can select a value greater than the remaining packet delay budget (PDB) of the sidelink data within the "SL-ResourceReservePeriodList" as the resource reservation interval P RVSP_TX . For example, in each resource pool, the "SL-ResourceReservePeriodList" can have up to 16 reservation interval values. These reservation interval values can indicate 0, 1 to 99, 100, 200, 300, 400, and 1000 ms, but are not limited thereto. If the selected resource reservation interval P RVSP_TX is greater than or equal to 100 ms, the UE can randomly select a value between [5, 15] and set it as the sidelink resource reselection counter (SL_RESOURCE_RESELECTION_COUNTER). On the other hand, if the resource reservation interval P RVSP_TX is less than 100 ms, the UE can be in Select a value randomly among them and can set it to the sidelink resource reselection counter (SL_RESOURCE_RESELECTION_COUNTER).

[0227] In addition, the UE can select the number of HARQ retransmissions and frequency resources within the values configured as RRC parameters. The UE can randomly select the time and frequency resources for a transmission opportunity from the resources indicated by the physical layer according to the remaining PDB of the sidelink data in the LCH and the amount of the selected frequency resources. For example, the UE can use the randomly selected resources to select the periodic resources located by the resource reservation interval P RVSP_TX Furthermore, when the UE selects at least one HARQ retransmission, the MAC layer of the UE can randomly select resources considering the minimum time gap of the PSFCH with the resource pool, the remaining PDB of the sidelink data, and the number of HARQ retransmissions. The UE can use the randomly selected resources to select the periodic resources located by the resource reservation interval P RVSP_TX Here, the UE can determine the first transmission as the initial transmission and can determine the subsequent transmissions as retransmissions in the resources periodically configured at each resource reservation interval P RVSP_TX

[0228] In addition, for example, when the UE generates a sidelink grant for a single MAC PDU transmission in the case where data exists in a specific LCH (S1807), the UE can select a resource pool associated with the LBT bandwidth (or RB set) where no LBT failure occurs within the configured resource pool according to whether the "sl-HARQ-FeedbackEnabled" of the corresponding LCH is enabled (S1808).

[0229] ​In addition, for example, when the UE performs sidelink channel state information (CSI) reporting in a case where data exists in a specific LCH, the UE may be associated with an LBT bandwidth (or set of RBs) in which LBT fails do not occur within the configured resource pool, and may select a resource pool regardless of whether the PSFCH is configured. Then, the UE may perform resource selection (or reselection) in the selected resource pool (S1805). In addition, the UE may deliver a sidelink grant to the HARQ entity (S1806). For example, the UE may continuously perform a transmission resource selection (or reselection) check operation until the UE determines to cancel the generation of a sidelink grant corresponding to a single MAC PDU transmission, or until the RRC releases the corresponding resource pool. The UE may select the HARQ retransmission count and frequency resources within the values configured to the RRC parameters. In addition, the UE may randomly select time and frequency resources for one transmission opportunity from the resources indicated by the physical layer based on the remaining PDB of the sidelink data in the LCH, the amount of the selected frequency resources, and the latency requirement of the SL-CSI. In addition, when selecting at least one HARQ retransmission, if resources indicated by the physical layer remain, the MAC layer of the UE may randomly select resources considering the minimum time gap of the PSFCH with the resource pool, the remaining PDB of the sidelink data, and the number of HARQ retransmissions. For example, when retransmission resources cannot be selected based on the resources assigned by a previous SCI, the UE may select retransmission resources in a different manner, but it may not be limited to a specific form.

[0230] In addition, for example, referring to Figure 18 , sidelink resource pools may be removed or added based on the ID of each SL BWP. Here, the UE may derive the size of the sidelink resource pool based on the starting RB position of the subchannel in the resource pool configuration associated with the identifier. In addition, when the "intraCellguardBand" parameter is configured for the UE, the UE may determine that multiple sets of RBs are configured. Therefore, the MAC layer of the UE may receive a report from the physical layer of the UE regarding the presence or absence of LBT fails in the multiple sets of RBs. Here, the physical layer of the UE may identify a resource pool included in the set of RBs in which LBT fails have not occurred. That is, the physical layer of the UE may verify the resource pool configuration in an implicit manner without a separate indication. As another example, the UE may explicitly identify the relationship of the set of RBs associated with the resource pool. Specifically, for example, when the RRB parameters for the SL BWP are configured for the UE, the UE may receive an indication of the associated RB set index within the resource pool configuration, but is not limited thereto.

[0231] Figure 19 shows a method of selecting a resource pool based on an LBT fail counter applicable to the present disclosure. Referring to Figure 19When generating LCH data that requires HARQ feedback in the MAC layer 1910 of the UE, the MAC layer 1910 of the UE may generate a sidelink grant and may perform resource pool selection. Here, the MAC layer 1910 of the UE may receive and count LBT result reports from the physical layer 1920 of the UE to select a resource pool. For example, LBT result reports may be performed for each LBT bandwidth (or RB set) or resource pool. As another example, the physical layer 1920 of the UE may report LBT failure count values to the MAC layer 1910 of the UE according to each LBT bandwidth (or RB set) or resource pool.

[0232] In addition, for example, the information included in the LBT result report may be information on each LBT bandwidth (or RB set) or resource pool where the LBT failure counter does not exceed a preset threshold. That is, if the LBT failure counter does not exceed the preset threshold, the MAC layer 1910 of the UE may obtain the LBT result report of each RB set or resource pool from the physical layer 1920. Specifically, for example, the resource pool selection process based on the LBT counter may be performed during the process of generating a sidelink grant, which may be as shown in Figure 20 For example, Figure 20 shows a method for resource selection performed by the UE considering the LBT counter that can be applied to the present disclosure. The UE may operate in the sidelink resource assignment mode 2 in a mode where the UE directly determines resources by sensing to perform sidelink communication. Referring to Figure 20 the UE may generate sidelink resources (S2001). For example, if a sidelink grant is received from the MAC layer, the physical layer of the UE may perform operations based on the sidelink grant. In addition, for example, the MAC layer of the UE may configure at least one LCH, and the LCH may be a unit for performing retransmission. Here, the MAC layer of the UE may indicate an LBT check for the SL BWP to the physical layer of the UE.

[0233] Referring to Figure 20, the UE can determine whether to configure multiple MAC PDUs by considering the data of the LCH. When the UE generates a sidelink grant for multiple MAC PDU transmissions in the case where data exists in a specific LCH (S2002), the UE can select a resource pool according to whether "sl-HARQ-FeedBackEnabled" of the corresponding LCH is enabled (S2003). In addition, the UE can compare the LBT failure counter value with a preset value (or threshold), and can select a resource pool. For example, when "sl-HARQ-FeedBackEnabled" of the corresponding LCH is set to "enabled", the UE can select a resource pool with an LBT failure counter value less than the preset value (or threshold) or a resource pool in which a PSFCH is configured in the LBT bandwidth (RB set), and can select one of the corresponding resource pools. As another example, the UE can select a resource pool with an LBT failure counter value less than the preset value (or threshold), a resource pool with the minimum LBT failure counter value in the LBT bandwidth (RB set), or a resource pool in which a PSFCH is configured in the LBT bandwidth (RB set). As another example, when the number of resource pools or LBT bandwidths (RB sets) with an LBT failure counter value less than the preset value (or threshold) is multiple, the UE can select the resource pool or LBT bandwidth (RB set) in different ways, and it is not limited to a specific embodiment (S2004).

[0234] On the other hand, when "sl-HARQ-FeedBackEnabled" of the LCH is set to "disabled", the UE can select one of a resource pool with an LBT failure counter value less than the preset value (or threshold) and a resource pool regardless of whether a PSFCH is configured in the LBT bandwidth (RB set). As another example, the UE can select one of a resource pool with an LBT failure counter value less than the preset value (or threshold) and a resource pool with the minimum LBT failure counter value in the LBT bandwidth (RB set), regardless of whether a PSFCH is configured in the LBT bandwidth (RB set). As another example, when the number of resource pools or LBT bandwidths (RB sets) with an LBT failure counter value less than the preset value (or threshold) is multiple, the UE can select the resource pool or LBT bandwidth (RB set) in different ways, and it is not limited to a specific embodiment (S2004).

[0235] Then, the UE can perform resource selection (or reselection) in the selected resource pool (S2005). In addition, the UE can deliver the sidelink grant to the HARQ entity (S2006). For example, the UE can continuously perform the transmission resource selection (or reselection) check operation until the UE determines to cancel the sidelink grant generation corresponding to multiple MAC PDU transmissions, or until the RRC releases the corresponding resource pool. For example, when the UE performs transmission resource reselection based on the transmission resource selection (or reselection) operation, the UE can select an available value within the "SL-ResourceReservePeriodList" configured by the RRC as the resource reservation interval P RVSP_TX . The UE can select a value within the "SL-ResourceReservePeriodList" that is greater than the remaining packet delay budget (PDB) of the sidelink data as the resource reservation interval P RVSP_TX . For example, in each resource pool, the "SL-ResourceReservePeriodList" can have up to 16 resource reservation period values. The reservation interval values can indicate 0, 1 to 99, 100, 200, 300, 400, and 1000 ms, but are not limited thereto. If the selected resource reservation interval P RVSP_TX is greater than or equal to 100 ms, the UE can randomly select a value between [5, 15] and set it as the sidelink resource reselection counter (SL_RESOURCE_RESELECTION_COUNTER). On the other hand, if the resource reservation interval P RVSP_TX is less than 100 ms, the UE can randomly select a value between and set it to the sidelink resource reselection counter (SL_RESOURCE_RESELECTION_COUNTER).

[0236] In addition, the UE can select the HARQ retransmission number and frequency resources within the values configured as RRC parameters. The UE can randomly select the time and frequency resources for one transmission opportunity from the resources indicated by the physical layer according to the remaining PDB of the sidelink data of the LCH and the amount of the selected frequency resources. For example, the UE can use the randomly selected resources to select the periodic resources located by the resource reservation interval P RVSP_TX . In addition, when the UE selects at least one HARQ retransmission, the MAC layer of the UE can randomly select resources considering the minimum time gap of the PSFCH of the resource pool, the remaining PDB of the sidelink data, and the number of HARQ retransmissions. The UE can use the randomly selected resources to select the periodic resources located by the resource reservation interval P RVSP_TXLocated periodic resources. Here, the UE may determine the first transmission as the initial transmission and may determine subsequent transmissions as at each resource reservation interval P RVSP_TX Retransmissions in periodically configured resources.

[0237] In addition, for example, when the UE generates a sidelink grant for a single MAC PDU transmission as the case where data exists in a specific LCH (S2007), the UE may select a resource pool associated with the LBT bandwidth (or RB set) within the configured resource pool according to whether "sl-HARQ-FeedBackEnabled" of the corresponding LCH is enabled, in which LBT counter is not greater than the threshold (S2008).

[0238] In addition, for example, when the UE performs sidelink CSI reporting as the case where data exists in a specific LCH, the UE may be associated with the RB set in which LBT failure does not occur in the configured resource pool and may select a resource pool regardless of whether PSFCH is configured. Then, the UE may perform resource selection (or reselection) in the selected resource pool (S2005). In addition, the UE may transmit the sidelink grant to the HARQ entity (S2006). For example, the UE may continuously perform the transmission resource selection (or reselection) check operation until the UE determines to cancel the sidelink grant generation corresponding to a single MAC PDU transmission or until the RRC releases the corresponding resource pool. The UE may select the HARQ retransmission number and frequency resources within the value configured to the RRC parameter. In addition, the UE may randomly select the time and frequency resources for one transmission opportunity from the resources indicated by the physical layer according to the remaining PDB of the sidelink data in the LCH, the amount of the selected frequency resources, and the latency requirement of the SL-CSI. In addition, when selecting at least one HARQ retransmission, if resources indicated by the physical layer of the UE remain, the UE may randomly select resources considering the minimum time gap with the PSFCH of the resource pool, the remaining PDB of the sidelink data, and the number of HARQ retransmissions. For example, when retransmission resources cannot be selected according to the resources assigned by the previous SCI, the UE may select retransmission resources in a different way, but it may not be limited to a specific form.

[0239] In addition, for example, referring to Figure 20, the sidelink resource pool can be removed or added based on the ID of each SL BWP. Here, the UE can derive the size of the sidelink resource pool based on the starting RB position of the subchannel in the resource pool configuration associated with the identifier. Also, when the "intraCellguardBand" parameter is configured for the UE, the UE can determine that multiple LBT bandwidths (RB sets) are configured. Accordingly, the MAC layer of the UE can receive a report from the physical layer of the UE regarding the presence or absence of LBT failures in the multiple LBT bandwidths (RB sets). Here, the physical layer of the UE can identify the resource pool included in the LBT bandwidth (RB set) in which the LBT failure has not occurred yet. That is, the physical layer of the UE can verify the resource pool configuration in an implicit manner without a separate indication. As another example, the UE can explicitly identify the relationship of the RB set related to the resource pool. Specifically, for example, when the RRB parameter for the BWP is configured for the UE, the UE can receive an indication of the associated LBT bandwidth (RB set) index within the resource pool configuration, but is not limited thereto.

[0240] Figure 21 illustrates a method for generating sidelink grants and selecting resources based on CBR applicable to the present disclosure. Refer to Figure 21 , data can be generated at time point n. The UE can generate a sidelink grant to transmit the generated data and can perform resource selection. For example, when the UE generates a sidelink grant, the UE can select a CR limit, the number of retransmission resources, the number of optional subchannels, the range of optional modulation and coding scheme (MCS) levels, and the transmission power. The UE can generate a sidelink grant considering the above parameters. That is, the UE can perform RB set and resource pool selection considering the above parameters and can thereby generate a sidelink grant without additional delay.

[0241] Figure 22 illustrates a CBR window in the sidelink unlicensed band applicable to the present disclosure. Refer to Figure 22 , a CBR window (2210, 2220) can be configured for each resource pool. For example, in Figure 22 , the CBR window (2210, 2220) can be configured for each RB set in the sidelink unlicensed band. Specifically, the CBR window 1 2210 can be configured to correspond to the resource pool 0 (RP0) 2230 and the resource pool 1 (RP1) 2240. In addition, the CBR window 2 2220 can be configured to correspond to the resource pool 2 (RP2) 2250 and the resource pool 3 (RP3) 2260. For example, in Figure 22In the above, the CBR window is similarly represented in resource pools located in the same LBT bandwidth (RB set), but this is merely an example and is not limited thereto. That is, the CBR window can be configured for each resource pool and can be configured in different forms. Specifically, for example, although the CBR window size can be configured identically in resource pools included in the same LBT bandwidth (RB set), the RSSI threshold can be set differently. As another example, by considering the characteristics of the sidelink unlicensed band, the CBR window size can be configured differently for each resource pool, and the CBR window size can be not limited to a specific form.

[0242] For example, when generating sidelink data in LCH (where "SL-HARQ-FeedbackEnabled" is set to "enabled"), the UE can determine resource pool 0 2230 and resource pool 2 2250 (where PSFCH is configured within the SL BWP) as candidate resource pools. The UE can verify the CBR of each of resource pool 0 2230 and resource pool 2 2250 that are candidate resource pools, and can select the resource pool with a CBR less than a preset value (or threshold) as the final resource pool. As another example, the UE can verify the CBR of each of resource pool 0 2230 and resource pool 2 2250 that are candidate resource pools, and can compare the CBRs, and can select the resource pool with a smaller CBR as the final resource pool.

[0243] On the other hand, when generating sidelink data in LCH (where "SL-HARQ-FeedbackEnabled" is set to "disabled"), the UE can determine all resource pools 02220, resource pool 1 2230, resource pool 2 2240, and resource pool 3 2250 as candidate resource pools regardless of whether PSFCH is configured within the SL BWP. The UE can verify the CBR of each of resource pool 02220, resource pool 1 2230, resource pool 2 2240, and resource pool 3 2250 that are candidate resource pools, and can select the resource pool with a CBR less than a preset value (or threshold) as the final resource pool. As another example, the UE can verify the CBR of each of resource pool 0 2220, resource pool 1 2230, resource pool 2 2240, and resource pool 3 2250 that are candidate resource pools, and can compare the CBRs, and can select the resource pool with the smallest CBR as the final resource pool. As another example, the UE can configure multiple final resource pools, and it is not limited to a specific form.

[0244] In addition, for example, the sidelink resource pool can be removed or added based on the ID of each SL BWP. Here, the UE can derive the size of the sidelink resource pool based on the starting RB position of the subchannel in the resource pool configuration associated with the identifier. In addition, when the "intraCellguardBand" parameter is configured for the UE, the UE can determine that multiple LBT bandwidths (RB sets) are configured. Therefore, the MAC layer of the UE can receive a report from the physical layer of the UE regarding the presence or absence of LBT failures in multiple LBT bandwidths (RB sets). Here, the physical layer of the UE can identify the resource pool included in the LBT bandwidth (RB set) in which the LBT failure has not occurred. That is, the physical layer of the UE can verify the resource pool configuration in an implicit manner without a separate indication. As another example, the UE can explicitly identify the relationship of the RB set associated with the resource pool. Specifically, for example, when the RRB parameter for the SL BWP is configured for the UE, the UE can receive an indication of the associated RB set index within the resource pool configuration, but is not limited thereto.

[0245] As another example, the UE can select the final resource pool by considering both the LBT failure counter and the CBR. Specifically, the UE can select the resource pool with a CBR less than a preset value (or threshold). Here, when the number of resource pools selected by the UE is multiple, the UE can select the final resource pool based on the LBT failure counter. As another example, the UE can select the resource pool with an LBT failure counter less than a preset value (or threshold). Here, when the number of resource pools selected by the UE is multiple, the UE can select the final resource pool according to the CBR.

[0246] For example, as described above, when the MAC layer of the UE generates a sidelink grant, the MAC layer of the UE can indicate the LBT check to the physical layer of the UE. The physical layer of the UE can perform the LBT and can report the result to the MAC layer of the UE. Here, the time point for verifying the LBT result for resource pool selection and the time point for actually transmitting the SCI and data can be different. Therefore, in the case of performing an additional LBT process, the physical layer of the UE may require additional operations. As another example, as described above, the UE can select a single resource pool by considering at least one of the LBT failure counter value and the CBR. Here, at the time point when the UE transmits the SCI and data, there may be a possibility that the LBT may fail, and a transmission failure may occur accordingly.

[0247] In view of the above, the UE can select at least one candidate resource pool. The UE can perform resource selection in at least one resource pool and can perform SCI and data transmission through the selected resource pool. Specifically, for example, the MAC layer of the UE can determine the resource pool in the set of RBs including LBT success in the candidate resource pools and can indicate transmission to the physical layer of the UE. For example, Figure 23 illustrates the resource pool configuration in the SL BWP applicable to the present disclosure. Referring to Figure 23 , the SL BWP of the unlicensed band can be configured for the UE. Here, the SL BWP can include at least one LBT bandwidth (or set of RBs) for broadband operation, and at least one resource pool can be configured in the LBT bandwidth (or set of RBs). For example, in Figure 23 , each of the resource pools 2310, 2320, 2330, and 2340 can be distinguished by an index and configured for the UE. In addition, each of the resource pools 2310, 2320, 2330, and 2340 can be different in terms of whether the resources for HARQ feedback are configured. For example, the resource pool in which the resources for HARQ feedback are configured can be denoted as w / PSFCH (with PSFCH), and the resource pool in which the resources for HARQ feedback are not configured can be denoted as w / o PSFCH (without PSFCH). Here, the PSFCH resources can be periodically configured in the logical sidelink time slots. Specifically, for example, when the PSFCH resource period is configured with four time slots, the PSCFH resources can be configured in the time slots with "sidelink time slot index mod 4 = 0" based on the logical sidelink time slots. The UE can select one or more candidate resource pools instead of a single resource pool, and by doing so, can operate considering LBT failures. For example, the UE can select as a candidate resource pool the resource pool in which the PSFCH resources for data transmission are configured in the LCH where HARQ feedback is activated. Here, the UE can select at least one candidate resource pool for each LBT bandwidth (or set of RBs). Referring to Figure 23 , when HARQ feedback is enabled, the candidate resource pools can be resource pool 0 2310, resource pool 2 2330, and resource pool 3 2340. On the other hand, when HARQ feedback is disabled, the candidate resource pools can be resource pool 0 2310, resource pool 1 2320, resource pool 2 2330, and resource pool 3 2340. That is, when HARQ feedback is disabled, the UE can select the resource pool regardless of whether the PSFCH is configured.

[0248] Here, when the UE configures at least one resource pool in units of the LBT bandwidth (or RB set), it can be as shown in Table 13 below. Specifically, when HARQ feedback is enabled, the UE can select Resource Pool 2 2330 as the candidate resource pool for RB Set 0, can select Resource Pool 0 2310 as the candidate resource pool for RB Set 1, and can select Resource Pool 3 2340 as the candidate resource pool for both RB Set 0 and RB Set 1. On the other hand, when HARQ feedback is prohibited, the UE can select Resource Pool 2 2330 as the candidate resource pool for RB Set 0, can select Resource Pool 0 2310 or Resource Pool 1 2320 as the candidate resource pool for RB Set 1, and can select Resource Pool 3 2340 as the candidate resource pool for both RB Set 0 and RB Set 1.

[0249] [Table 13]

[0250]

[0252] For example, in Figure 23 since the resource pool configured in RB Set 0 is Resource Pool 2 2330 in which HARQ feedback resources are configured, Resource Pool 2 2330 can be selected regardless of whether HARQ feedback is enabled or disabled in the LCH. On the other hand, the resource pools configured in RB Set 1 can be Resource Pool 0 2310 in which HARQ feedback resources are configured and Resource Pool 1 2320 in which HARQ feedback resources are not configured. Therefore, when HARQ feedback of the LCH is enabled, the UE can select Resource Pool 0 2310 as the candidate resource pool. On the other hand, when HARQ feedback of the LCH is disabled, the UE can select Resource Pool 0 2310 or Resource Pool 1 2320 as the candidate resource pool. In addition, if the UE successfully performs LBT in both RB Set 0 and RB Set 1 and is able to occupy the channel, the UE can select Resource Pool 3 2340 configured for broadband operation as the candidate resource pool.

[0253] Figure 24 shows a method for the UE to perform resource selection considering the LBT counter applicable to the present disclosure. For example, according to sidelink resource assignment mode 2, the UE can operate in a mode where the UE directly determines the resources for performing sidelink communication by sensing. Referring to Figure 24 , the UE can generate sidelink resources (S2401). For example, if a sidelink grant is received from the MAC layer of the UE, the physical layer of the UE can perform operations based on the sidelink grant. In addition, for example, the MAC layer of the UE can configure at least one LCH, and the LCH can be a unit for performing retransmission. Here, the MAC layer of the UE can indicate the LBT check for the SL BWP to the physical layer of the UE.

[0254] Here, with reference to Figure 24 , the UE can determine whether to configure multiple MAC PDUs based on the data of the LCH. When the UE generates a sidelink grant for multiple MAC PDU transmissions in the case where data exists in a specific LCH (S2402), the UE can select a resource pool according to whether "sl-HARQ-FeedBackEnabled" of the corresponding LCH is enabled (S2403). In addition, the UE can consider candidate resource pools to perform resource pool selection. For example, when "sl-HARQ-FeedbackEnabled" of the corresponding LCH is set to "enabled", the UE can select candidate resource pools based on HARQ feedback enablement (S2404), and can perform transmission resource selection in each candidate resource pool (S2405). On the other hand, when "sl-HARQ-FeedbackEnabled" of the LCH is set to "disabled", the UE can select candidate resource pools based on HARQ feedback disablement (S2404), and can perform transmission resource selection in each candidate resource pool (S2405). In addition, the UE can deliver the sidelink grant to the HARQ entity (S2406).

[0255] In addition, for example, when the UE generates a sidelink grant for a single MAC PDU transmission in the case where data exists in a specific LCH (S2407), the UE can select a resource pool according to whether "sl-HARQ-FeedBackEnabled" of the corresponding LCH is enabled (S2408). For example, when "sl-HARQ-FeedbackEnabled" of the corresponding LCH is set to "enabled", the UE can select candidate resource pools based on HARQ feedback enablement, and can perform transmission resource selection in each candidate resource pool (S2405). On the other hand, when "sl-HARQ-FeedbackEnabled" of the LCH is set to disabled, the UE can select candidate resource pools based on HARQ feedback disablement, and can perform transmission resource selection in each candidate resource pool (S2405). In addition, the UE can deliver the sidelink grant to the HARQ entity (S2406).

[0256] Figure 25illustrates sidelink operations applicable to the present disclosure. The MAC layer of the UE may select a final resource pool, excluding the resource pools within the LBT bandwidth (or RB set) where LBT failures have occurred. That is, the MAC layer of the UE may select the resource pools within the LBT bandwidth (or RB set) where LBT is successful. Then, the MAC layer of the UE may indicate SCI and data transmission to the physical layer of the UE through the selected resource pool. For example, if LBT failures do not occur only in RB set 0, the MAC layer of the UE may select one of the resource pools included in RB set 0. On the other hand, if LBT failures do not occur only in RB set 1, the MAC layer of the UE may select one of the resource pools included in RB set 1. As another example, if LBT failures do not occur in both RB set 0 and RB set 1, the MAC layer of the UE may select one of all the candidate resource pools. Specifically, for example, referring to Figure 25 , the MAC of the UE may receive a transmission request from the sidelink HARQ entity (S2501). Here, the MAC layer of the UE may determine whether the requested transmission is an initial transmission (S2502). For example, when the requested transmission is an initial transmission (S2503), the MAC layer of the UE may store the MAC PDU and the sidelink grant (S2504), and may perform an LBT check in the SL BWP (S2505). Then, the MAC layer of the UE may select a resource pool within the LBT bandwidth (or RB set) where LBT is successful (S2506), and may perform the transmission (S2507). Here, the MAC layer of the UE may indicate to the physical layer of the UE to send the SCI based on the sidelink transmission information. In addition, the MAC layer of the UE may indicate to the physical layer of the UE to generate the transmission.

[0257] On the other hand, when the requested transmission is not an initial transmission (S2508), the MAC layer of the UE may perform a retransmission (S2508). Then, the MAC layer of the UE may store the sidelink grant (S2509), and may perform an LBT check in the SL BWP (S2510). Then, the MAC layer of the UE may perform the transmission based on successful LBT (S2507). Here, the MAC layer of the UE may indicate to the physical layer of the UE to send the SCI based on the sidelink transmission information. In addition, the MAC layer of the UE may indicate to the physical layer of the UE to generate the transmission.

[0258] As another example, Figure 26 illustrates an SL BWP including a plurality of resource block (RB) sets. Referring to Figure 26, the resource pool configuration within the SL BWP can be configured to always include multiple LBT bandwidths (or RB sets). However, this is merely an example and is not limited thereto. For example, although the resource pool 2610 is configured with multiple LBT bandwidths (or RB sets), the UE can select the resource pool based on the HARQ feedback enable / disable state of the LCH as described above. Here, if the resource pool 2610 includes multiple LBT bandwidths (or RB sets), the transmission opportunity selection operation for the UE's initial transmission (or retransmission) may be problematic. Specifically, after selecting the resource pool, the UE can randomly select a transmission opportunity for the initial transmission (or retransmission) from the resource set (or resources) indicated by the UE's physical layer. For example, the UE can implicitly identify which LBT bandwidth (or RB set) the corresponding resource is included in, but the UE can select the transmission opportunity without considering the LBT success status. Therefore, if the UE randomly selects a resource with an unsuccessful LBT, the UE may not perform the transmission even though the UE randomly selects a resource within the resource pool. Specifically, for example, in Figure 26 , the resource pool 0 2610 can include two LBT bandwidths (or RB sets). The UE can select the resource pool 0 2610 and can randomly select a resource set (or resources) included in the two LBT bandwidths (or RB sets). Here, if the UE selects the resource pool 0 2610, randomly selects a resource included in the RB set 0, and thereby determines the transmission opportunity, the UE can perform the transmission only when the LBT in the corresponding RB set 0 is successful. For example, if the LBT fails in the RB set 0 and the LBT is successful in the RB set 1, the UE needs to select a resource in the RB set 1 instead of the resource in the RB set 0 to perform the transmission. That is, the UE may need to perform the transmission opportunity selection by considering the LBT-related information. Specifically, the UE can perform the transmission opportunity selection by considering the LBT results, LBT counters, and candidate transmission opportunities for each RB set (or LBT bandwidth), which will be described below.

[0259] For example, Figure 27 illustrates a method of selecting a transmission opportunity based on candidate transmission opportunities applicable to the present disclosure. Referring to Figure 27 , when the UE selects a transmission opportunity, the UE can select available candidate resources 2710, 2720 for each LBT bandwidth (or RB set). Specifically, for example, when the UE performs SCI and data transmission, the MAC layer of the UE can receive a report on the LBT result from the physical layer of the UE and can determine the resource to be used for the actual transmission among the candidate resources. For example, in Figure 27In [the case where], if the UE fails in the LBT for RB set 1 and succeeds in the LBT for RB set 0, the UE may determine the candidate transmission resource 12710 as a transmission opportunity. On the other hand, if the UE fails in the LBT for RB set 0 and succeeds in the LBT for RB set 1, the UE may determine the candidate transmission resource 2 2720 as a transmission opportunity. As another example, if the UE succeeds in the LBT for both RB set 0 and RB set 1, the UE may determine one of the candidate transmission resource 1 2710 and the candidate transmission resource 2 2720 as a transmission opportunity.

[0260] That is to say, if the UE succeeds in the LBT only in one LBT bandwidth (or RB set), the UE may determine the candidate resource within the RB set where the LBT succeeds as a transmission opportunity. On the other hand, if the UE succeeds in the LBT in multiple LBT bandwidths (or RB sets), the UE may determine one of the candidate resources as a transmission opportunity. Here, for example, when the UE can verify the LBT counter value in the LBT bandwidth (or RB set), the UE may select the resource within the RB set with a small LBT counter value, but it is not limited thereto.

[0261] As another example, the UE may set candidate resources for the LBT bandwidth (or RB set). As described above, candidate resources may be determined for each LBT bandwidth (or RB set), and candidate resources for multiple LBT bandwidths (or RB sets) may also be determined. If the UE succeeds in the LBT in multiple LBT bandwidths (or RB sets), the UE may determine the candidate resources for the multiple LBT bandwidths (or RB sets) as a transmission opportunity, but it is not limited thereto.

[0262] Figure 28 Illustrates a method for determining a transmission opportunity based on LBT operation applicable to the present disclosure. Refer to Figure 28 , the UE may determine a transmission opportunity based on LBT. Specifically, for example, referring to Figure 28 of (a), the MAC layer 2810 of the UE may select a transmission opportunity based on the LBT result. The MAC layer 2810 of the UE may request the physical layer 2820 of the UE to perform an LBT check and may receive a report on the LBT result for each RB set based thereon. Here, the MAC layer 2810 of the UE may select the resource within the LBT bandwidth (or RB set) where the LBT succeeds. For example, as Figure 26As shown, when the UE selects a transmission opportunity in the case of configuring a single resource pool in an SL BWP including multiple LBT bandwidths (or RB sets), the MAC layer of the UE may perform transmission opportunity selection based on the LBT results reported from the physical layer of the UE. For example, if LBT is reported successful in RB set 0 and LBT is reported failed in RB set 1, the MAC layer 2810 of the UE may select a transmission opportunity within RB set 0.

[0263] In addition, for example, referring to Figure 28 (b) of, the MAC layer 2810 of the UE may select a transmission opportunity based on the LBT counter value. For example, the physical layer 2820 of the UE may continuously report the LBT results to the MAC layer 2810 of the UE for each LBT bandwidth (or RB set). Here, the MAC layer 2820 of the UE may select a transmission opportunity based on the LBT counter value reported for each LBT bandwidth (or RB set). For example, as shown in Figure 26 , when the UE selects a transmission opportunity for configuring a single resource pool in an SL BWP including multiple RB sets, the MAC layer of the UE may perform transmission opportunity selection based on the LBT results reported from the physical layer of the UE through the LBT failure counter value. For example, if the LBT counter value of RB set 0 is less than the LBT counter value of RB set 1, the MAC layer 2810 of the UE may select a transmission opportunity within RB set 0.

[0264] As another example, the UE may select a HARQ retransmission resource in a resource pool in which a PSFCH resource is configured. Here, the UE may need to ensure the interval between the two selected resources so as to consider the processing time for HARQ feedback transmission and reception through a minimum time gap. For example, the minimum time gap may be as shown in Table 14 below. Here, the maximum channel occupancy time (MCOT) limit may be set to the sidelink unlicensed band. That is, the UE may consider using the unlicensed band and perform sidelink communication based on the MCOT which is a limited time. Here, due to the MCOT limit, the UE may not perform HARQ feedback transmission and reception, and considering this, scheduling may be required in consecutive sidelink time slots. Considering the above, the UE may select resources without considering the minimum time gap, which will be described below.

[0265] [Table 14]

[0266]

[0268] For example, the MAC layer of the UE can select the number of one or more HARQ retransmissions. Here, when there are remaining available resources in the resources indicated by the physical layer in the resource pool, the MAC layer of the UE can select resources by considering the sidelink DRX active time of the target UE, the amount of frequency resources, the number of retransmission resources, the remaining PDB of the LCH data, and the SL-SCI latency requirement. For example, when the MAC layer of the UE selects resources, the aforementioned minimum time gap can be ensured between two resources that are the selected resources, as Figure 29 shown. For example, Figure 29 illustrates a case of ensuring a minimum time gap in a transmission opportunity applicable to the present disclosure. Referring to Figure 29 , by considering the processing time of transmission and reception, a minimum time gap can be set between each of the transmission opportunities 2910, 2920, and 2930. Here, the selected resources can be determined as transmission opportunities. For example, the first resource can be determined as the initial transmission opportunity, and the remaining resources can be determined as retransmission opportunities. In addition, all transmission opportunities can be determined as the selected sidelink grants. For example, when the inter-UE coordination function is activated in the UE, the MAC layer of the UE can select resources within the set of preferred resources and the set of resources indicated by the physical layer.

[0269] In addition, for example, the retransmission resources can be indicated by the time resource assignment within the first SCI, and if the higher layer parameter sl-MaxNumerReserve indicating the number of retransmission resources is 2, the retransmission resources can be represented by 5 bits. In addition, if the higher layer parameter sl-MaxNumerReserve indicating the number of retransmission resources is 3, the retransmission resources can be represented by 9 bits. For example, if sl-MaxNumerReserve = 3, up to three transmission opportunities can be set, and each transmission opportunity can be indicated in such a way that the starting logical sidelink time slot position and the subchannel position are determined according to the TRIV indicated by the time resource assignment and the FRIV indicated by the frequency resource assignment.

[0270] On the other hand, the above-mentioned MCOT can exist in the unlicensed band. For example, when two resources are selected, the two resources can be restricted to be selected while ensuring the minimum time gap within the MCOT. Considering the above situation, the transmission opportunity using the two selected resources can be determined as consecutive time slots. Specifically, Figure 30 illustrates a method of determining a transmission opportunity using consecutive time slots in the unlicensed band applicable to the present disclosure. Referring to Figure 30, the transmission opportunities 3010, 3020, and 3030 can be determined as consecutive time slots. The UE can select at least one retransmission, and can select available resources from the resources indicated by the physical layer when selecting each resource. Here, the UE may not guarantee the minimum time gap between the two selected resources. For example, the first resource among the resources selected by the UE can be determined as the initial transmission opportunity, and the remaining resources can be determined as retransmission opportunities. In addition, for example, the selected resources can be limited to the resources within the MCOT. That is, when the UE occupies the channel through the LBT process, the UE can select the transmission opportunity by considering the MCOT that can occupy the channel. Through the above, even in the resource pool where the PSFCH resources are configured, retransmission resources may be selected without satisfying the minimum time gap.

[0271] Figure 31 is a flowchart showing a method for the UE to perform sidelink communication, to which the present disclosure can be applied. Referring to Figure 31 , the UE can receive sidelink resource pool configuration information from the base station based on higher layer signaling. Here, if data is generated in the LCH based on the sidelink resource pool configuration information, the UE can generate a sidelink grant (S3110). Here, when HARQ feedback is set to the data generated in the LCH based on the sidelink resource pool configuration information (S3120), the UE can select a sidelink resource pool based on at least one of the LBT result, the LBT failure counter, and the CBR, in which the PSFCH is configured (S3130). Then, the UE can select a sidelink resource from the selected sidelink resource pool and can perform sidelink transmission (S3140). On the other hand, when HARQ feedback is not set to the data generated in the LCH based on the sidelink resource pool configuration information (S3120), the UE can select a sidelink resource pool regardless of the PSFCH configuration based on at least one of the LBT result, the LBT failure counter, and the CBR (S3150). Then, the UE can select a sidelink resource from the selected sidelink resource pool and can perform sidelink transmission (S3140).

[0272] Here, for example, as described above, the UE can select a resource pool based on the LBT result from one or more sidelink resource pools included in the LBT bandwidth that occupies the channel through successful LBT. As another example, as described above, the UE can select a sidelink resource pool from one or more sidelink resource pools included in the LBT bandwidth (the LBT counter of which is less than a preset value) based on the LBT counter.

[0273] Figure 32 is a flowchart showing a method for the UE to perform sidelink communication, to which the present disclosure can be applied. Referring to Figure 32, the UE may generate a sidelink grant (S3210) based on the data generated in the LCH. For example, when a sidelink resource pool including multiple LBT bandwidths is configured for the UE based on the sidelink resource pool configuration information (S3220), the UE may set candidate transmission opportunities based on the LBT bandwidths within the sidelink resource pool (S3230). For example, each candidate transmission opportunity may be set for each LBT bandwidth, but is not limited thereto. Then, the UE may select a sidelink resource pool including the multiple LBT bandwidths based on at least one of the LBT result, the LBT failure counter, and the CBR. Here, the UE may select a specific transmission opportunity from the candidate transmission opportunities based on at least one of the LBT result, the LBT failure counter, and the CBR (S3240). On the other hand, when a sidelink resource pool including a single LBT bandwidth is configured for the UE (S3220), the UE may select the sidelink resource pool based on at least one of the LBT result, the LBT failure counter, and the CBR, and may randomly select a transmission opportunity from the selected sidelink resource pool, which is described above (S3250).

[0274] Figure 33 FIG. is a diagram showing a base station device and a UE device to which the present disclosure can be applied.

[0275] The base station device 3300 may include a processor 3320, an antenna unit 3312, a transceiver 3314, and a memory 3316.

[0276] The processor 3320 performs baseband-related signal processing and may include a higher layer processor 3330 and a physical layer processor 3340. The higher layer processor 3330 may process operations of the media access control (MAC) layer, the radio resource control (RRC) layer, or a higher layer thereof. The physical layer processor 3340 may process operations of the physical (PHY) layer (e.g., uplink received signal processing, downlink transmitted signal processing). In addition, in order to perform baseband-related signal processing, the processor 3320 may also overall control the operation of the base station device 3300.

[0277] The antenna unit 3312 may include one or more physical antennas and may support multiple-input multiple-output (MIMO) transmission and reception in the case of including multiple antennas. In addition, beamforming may be supported.

[0278] The memory 3316 may store information processed by calculation related to the operation of the base station device 3300, such as software, an operating system, an application, etc. of the processor 3320, and may include components such as a buffer.

[0279] The processor 3320 of the base station 3300 may be configured to implement the operation of the base station in the examples described herein.

[0280] The UE device 3350 may include a processor 3370, an antenna unit 3362, a transceiver 3364, and a memory 3366. For example, here, the UE device 3350 may perform communication with the base station device 3300. As another example, here, the UE device 3350 may perform SL communication with another UE device. That is, the UE device 3350 used here refers to a device capable of communicating with at least one of the base station device 3300 and other UE devices, and is not limited to communicating with a specific device.

[0281] The processor 3370 performs baseband-related signal processing and may include a higher layer processor 3380 and a physical layer processor 3390. The higher layer processor 3380 may handle operations of the MAC layer, RRC layer, or higher layers. The physical layer processor 3390 may handle operations of the PHY layer (e.g., downlink received signal processing, uplink transmitted signal processing). In addition, in order to perform baseband-related signal processing, the processor 3370 may also control the overall operation of the UE device 3350.

[0282] The antenna unit 3362 may include one or more physical antennas and may support MIMO transmission and reception in the case of including multiple antennas. In addition, beamforming may be supported.

[0283] The memory 3366 may store computationally processed information related to the operation of the UE device 3350, such as the processor 3370, software, an operating system, applications, etc., and may include components such as buffers.

[0284] The terminal device 3350 according to an example of the present disclosure may be associated with a vehicle. For example, the terminal device 3350 may be integrated in a vehicle, may be located in a vehicle, or may be located on a vehicle. In addition, the terminal device 3350 according to the present disclosure may be the vehicle itself. In addition, the terminal device 3350 according to the present disclosure may be at least one of a wearable terminal, an AR / VR, an Internet of Things (IoT) terminal, a robot terminal, and a public safety terminal. The terminal device 3350 to which the present disclosure may be applied may include various types of communication devices (which support interactive services using a side link) for services such as Internet access, service execution, navigation, real-time information, autonomous driving, and safety and risk diagnosis. In addition, the terminal device 3350 may include an AR / VR device capable of performing side link operations or any type of communication device capable of performing a relay operation as a sensor.

[0285] Here, the vehicles to which the present disclosure is applied may include autonomous vehicles, semi-autonomous vehicles, and non-autonomous vehicles. Also, although the terminal device 3350 according to an example of the present disclosure is described as being associated with a vehicle, at least one of the UEs may not be associated with a vehicle. However, it is provided only as an example and should not be construed as limiting the application of the present invention.

[0286] In addition, the terminal device 3350 according to an example of the present disclosure may include various types of communication devices capable of performing cooperation, and the cooperation may support interactive services using a sidelink. That is, the terminal device 3350 may directly support interactive services using a sidelink and may be used as a cooperation device for supporting interactive services using a sidelink.

[0287] In addition, for example, the terminal device 3350 may receive sidelink resource pool configuration information from the base station device 3300 based on higher layer signaling. Here, if data is generated in the LCH based on the sidelink resource pool configuration information, the terminal device 3350 may generate a sidelink grant. Here, when HARQ feedback is set for the data generated in the LCH based on the sidelink resource pool configuration information, the terminal device 3350 may select a sidelink resource pool based on at least one of the LBT result, the LBT failure counter, and the CBR, in which the PSFCH is configured. Then, the terminal device 3350 may select a sidelink resource from the selected sidelink resource pool and may perform sidelink transmission. On the contrary, when HARQ feedback is not set for the data generated in the LCH based on the sidelink resource pool configuration information, the terminal device 3350 may select a sidelink resource pool based on at least one of the LBT result, the LBT failure counter, and the CBR without considering the PSFCH configuration. Then, the terminal device 3350 may select a sidelink resource from the selected sidelink resource pool and may perform sidelink transmission. In addition, for example, when a sidelink resource pool including a plurality of LBT bandwidths is configured to the terminal device 3350 based on the sidelink resource pool configuration information, the terminal device 3350 may set candidate transmission opportunities based on the LBT bandwidth within the sidelink resource pool. Then, the terminal device 3350 may select a sidelink resource pool including a plurality of LBT bandwidths based on at least one of the LBT result, the LBT failure counter, and the CBR. Here, the terminal device 3350 may select a specific transmission opportunity from the candidate transmission opportunities based on at least one of the LBT result, the LBT failure counter, and the CBR.

[0288] In addition, the various examples of the present disclosure can be implemented by hardware, firmware, software, or a combination thereof. In the case of implementation by hardware, the examples can be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), general purpose processors, controllers, microcontrollers, microprocessors, etc.

[0289] The scope of the present invention includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) for enabling the operations of the methods according to the various embodiments, and devices or non-transitory computer-readable media executable on a computer storing such software or instructions.

[0290] The various embodiments of the present disclosure are used to explain the representative aspects of the present disclosure, rather than listing all possible combinations, and the descriptions made in the various embodiments can be applied independently or in combinations of two or more.

[0291] Industrial Applicability

[0292] The above can be applied to other systems.

Claims

1. A sidelink communication method for a user equipment (UE) to perform sidelink communication in an unlicensed frequency band in a wireless communication system, the method comprises: receiving, by the UE, sidelink resource pool configuration information from a base station based on higher layer signaling; generating a sidelink (SL) grant if data is generated in a logical channel (LCH) based on the sidelink resource pool configuration information; selecting a sidelink resource pool according to whether hybrid automatic repeat request (HARQ) feedback is configured for the data generated in the LCH based on the sidelink resource pool configuration information; and selecting a sidelink resource from the selected sidelink resource pool and performing sidelink transmission, wherein the UE performs a listen-before-talk (LBT) operation on the unlicensed frequency band during the process of selecting the sidelink resource pool, and performs the sidelink resource pool selection based on at least one of an LBT result, an LBT failure counter, and a channel busy rate (CBR).

2. The sidelink communication method according to claim 1, wherein when the HARQ feedback is configured for the UE, the UE selects the sidelink resource pool from one or more sidelink resource pools in which a physical sidelink feedback channel (PSFCH) is configured, and when the HARQ feedback is not configured for the UE, the UE selects the sidelink resource pool from the one or more sidelink resource pools regardless of whether the PSFCH is configured.

3. The sidelink communication method according to claim 2, wherein the UE selects the resource pool from one or more resource pools included in an LBT bandwidth with a successful LBT based on the LBT result.

4. The sidelink communication method according to claim 3, wherein the UE selects the resource pool from the one or more resource pools included in the LBT bandwidth with an LBT counter less than a preset value based on the LBT counter.

5. The sidelink communication method according to claim 1, wherein, when a first sidelink resource pool including multiple LBT bandwidths is configured for the UE, at least one candidate transmission opportunity is configured in the first sidelink resource pool including the multiple LBT bandwidths based on each LBT bandwidth, and when the first sidelink resource pool is selected based on at least one of the LBT result, the LBT failure counter, and the CBR, the UE selects a first transmission opportunity from the one or more candidate transmission opportunities in the first sidelink resource pool based on at least one of the LBT result, the LBT failure counter, and the CBR.

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