Method and apparatus for performing sidelink communication based on LBT process in unlicensed band

Abstract

A wireless user equipment (UE) performing a listen before talk (LBT) operation in a sidelink unlicensed band in a wireless communication system may be configured to select a resource pool and a resource for sidelink communication based on a resource pool and resource selection procedure, perform the LBT procedure using the resource pool and the resource selected based on the sidelink unlicensed band, and perform a listen before talk (LBT) operation using the selected resource pool and resource based on the sidelink unlicensed band. A consistent LBT failure trigger state is verified based on the LBT procedure, and the resource for the sidelink communication is selected based on a transmission resource selection procedure when a consistent LBT failure is triggered.

Description

Technical Field

[0001] The present disclosure relates to a method and an apparatus for performing sidelink communication based on a listen-before-talk (LBT) procedure in an unlicensed band of a wireless communication system. More specifically, the present disclosure relates to a method and an apparatus for performing sidelink communication based on a consistent LBT failure. Background Art

[0003] The International Telecommunication Union (ITU) has developed an International Mobile Telecommunications (IMT) framework and standards. Also, continuous discussions on 5th generation (5G) communication are underway 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 units 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-massive machine type communication (uMTC), and ultra-reliable and low-latency communication (URLLC).

[0006] In addition, vehicle-to-everything (V2X) communication can be considered, which is a communication method of exchanging or sharing road infrastructure and information (e.g., traffic conditions) 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 a speed notification to a vehicle. Summary of the Invention Technical Subject

[0008] The technical subject matter 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 an apparatus for performing sidelink communication based on a listen-before-talk (LBT) procedure in an unlicensed band of a wireless communication system.

[0010] The technical subject matter of the present disclosure relates to a method and an apparatus for performing sidelink communication based on a consistent LBT failure in an unlicensed band of a wireless communication system.

[0011] The technical subject matter of the present disclosure relates to a method and an apparatus for performing sidelink communication based on a consistent LBT failure detection unit.

[0012] 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.

[0013] Technical Solution

[0014] According to an aspect of the present disclosure, there is provided a wireless user equipment (UE) that performs a listen-before-talk (LBT) operation in an unlicensed band of a sidelink in a wireless communication system. The wireless UE includes at least one antenna configured to transmit and receive one or more wireless signals, at least one processor, and a memory configured to store instructions for the wireless UE when executed by the at least one processor. The wireless UE is configured to select a resource pool and resources for sidelink communication based on a resource pool and a resource selection process, perform a listen-before-talk (LBT) process using the resource pool and the resources selected based on the sidelink unlicensed band, verify a consistent LBT failure trigger status based on the LBT process, and when the consistent LBT failure is triggered, select the resources for the sidelink communication based on a transmission resource selection process.

[0015] In addition, according to an aspect of the present disclosure, the consistent LBT failure trigger status can be verified according to a resource block (RB) set, the resource pool includes a plurality of RB sets, and when the consistent LBT failure is triggered in a first RB set among the plurality of RB sets included in the resource pool and the consistent LBT failure is not triggered in a second RB set among the plurality of RB sets included in the resource pool, the wireless UE can perform the resource selection process in the second RB set and select the resources for the sidelink communication.

[0016] In addition, according to an aspect of the present disclosure, when the consistent LBT fails in the first RB set and does not fail in the second RB set, the medium access control (MAC) layer of the wireless UE may release the sidelink authorization selected based on the resource selection process, and may select the resources for the sidelink communication included in the second RB set.

[0017] In addition, according to an aspect of the present disclosure, when the consistent LBT fails in the first RB set and does not fail in the second RB set, the MAC layer of the wireless UE may deliver the consistent LBT failure information to the physical layer of the wireless UE. The physical layer of the wireless UE may determine a candidate resource set based on the consistent LBT failure information and deliver it to the MAC layer of the wireless UE, and the MAC layer of the wireless UE may select at least one resource from the candidate resource set as the resource for the sidelink communication.

[0018] In addition, according to an aspect of the present disclosure, the consistent LBT failure trigger status may be verified for each resource pool. A single sidelink bandwidth part (SL BWP) may include multiple resource pools. When the consistent LBT fails in a first resource pool among the multiple resource pools included in the SL BWP and the consistent LBT does not fail in a second resource pool among the multiple resource pools included in the SL BWP, the wireless UE may select the second resource pool based on the resource pool and the resource selection process, and may perform the resource selection process in the second resource pool and select the resources for the sidelink communication.

[0019] In addition, according to an aspect of the present disclosure, when the consistent LBT fails in all of the multiple resource pools included in the SL BWP, the wireless UE may release the connection with another wireless UE based on sidelink radio link failure (SL RLF).

[0020] In addition, according to an aspect of the present disclosure, the consistent LBT failure reporting may be performed by an SL LBT failure medium access control (MAC) control element (CE), and each C field of the SL LBT failure MAC CE may be configured based on a consistent LBT failure reporting unit.

[0021] Technical effects

[0022] According to the present disclosure, a method and an apparatus for performing sidelink (SL) communication in a wireless communication system may be provided.

[0023] According to the present disclosure, it relates to a method and an apparatus for performing sidelink communication based on a listen-before-talk (LBT) procedure in an unlicensed band of a wireless communication system.

[0024] According to the present disclosure, it relates to a method and an apparatus for performing sidelink communication based on a consistent LBT failure in an unlicensed band of a wireless communication system.

[0025] According to the present disclosure, it relates to a method and an apparatus for performing sidelink communication based on a consistent LBT failure detection unit.

[0026] 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 according to the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 An example of a new radio (NR) frame structure to which the present disclosure can be applied is shown.

[0029] Figure 2 An NR resource structure to which the present disclosure can be applied is shown.

[0030] Figure 3 An NR sidelink time slot structure to which the present disclosure can be applied is shown.

[0031] Figure 4 An NR sidelink frequency to which the present disclosure can be applied is shown.

[0032] Figure 5 An NR sidelink resource pool configuration to which the present disclosure can be applied is shown.

[0033] Figure 6 An unlicensed band for each area for NR sidelink communication to which the present disclosure can be applied is shown.

[0034] Figure 7 The use of a 5 gigahertz (GHz) unlicensed band to which the present disclosure can be applied is shown.

[0035] Figure 8 A method for increasing bandwidth considering power spectral density (PSD) limitations to which the present disclosure can be applied is shown.

[0036] Figure 9 A method for configuring a guard band considering a shared frequency band within a cell to which the present disclosure can be applied is shown.

[0037] Figure 10 An unlicensed band applicable to the present disclosure is shown.

[0038] Figure 11Shows a sidelink resource pool to which the present disclosure can be applied.

[0039] Figure 12 Shows a sidelink discontinuous reception (DRX) hybrid automatic repeat request (HARQ) round-trip time (RTT) timer to which the present disclosure can be applied.

[0040] Figure 13 Shows a method for a sidelink timer in an operation resource pool to which the present disclosure can be applied, where a physical sidelink feedback channel (PSFCH) is not configured in the resource pool.

[0041] Figure 14 Shows a sidelink HARQ feedback operation to which the present disclosure can be applied.

[0042] Figure 15 Shows a physical sidelink shared channel (PSSCH)-PSFCH mapping for HARQ feedback transmission to which the present disclosure can be applied.

[0043] Figure 16 Shows a channel occupancy time (COT) structure to which the present disclosure can be applied.

[0044] Figure 17 Shows a method for detecting a consistent LBT failure to which the present disclosure can be applied.

[0045] Figure 18 Shows a LBT failure media access control (MAC) control element (CE) to which the present disclosure can be applied.

[0046] Figure 19 Shows a method for detecting a consistent LBT failure based on an RB set to which the present disclosure can be applied.

[0047] Figure 20 Shows a method for a MAC layer of a user equipment (UE) to select a resource within a resource pool based on a consistent LBT failure to which the present disclosure can be applied.

[0048] Figure 21 Is a flowchart showing a method for detecting a consistent LBT failure based on an RB set to which the present disclosure can be applied.

[0049] Figure 22 Shows a method for determining a candidate resource set based on a consistent LBT failure to which the present disclosure can be applied.

[0050] Figure 23 Shows a situation of performing a consistent LBT failure based on a resource pool to which the present disclosure can be applied.

[0051] Figure 24 Shows a resource pool selection operation to which the present disclosure can be applied.

[0052] Figure 25 Shows a method for detecting consistent LBT failures based on a resource pool to which the present disclosure can be applied.

[0053] Figure 26 Shows an SL LBT failure MAC CE to which the present disclosure can be applied.

[0054] Figure 27 Shows an SL LBT failure MAC CE considering SL carrier aggregation to which the present disclosure can be applied.

[0055] Figure 28 Shows an SL LBT failure MAC CE reporting operation to which the present disclosure can be applied.

[0056] Figure 29 Shows a method for transmitting an SL LBT failure MAC CE to which the present disclosure can be applied.

[0057] Figure 30 Is a flowchart showing a method for performing sidelink communication based on consistent LBT failures to which the present disclosure can be applied.

[0058] Figure 31 Is a diagram showing a base station device and a terminal device to which the present disclosure can be applied. Detailed implementation manners

[0060] The following will more comprehensively describe various examples of the present disclosure with reference to the accompanying 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.

[0061] 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 specified, the same reference numerals are understood to represent the same elements, features, and structures.

[0062] It will be understood that when an element is referred to as being "connected to", "coupled to", or "accessed" another element, it can be directly connected, coupled, or accessed to the other element, or there may be intermediate elements. In addition, it will also 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.

[0063] 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. Thus, 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.

[0064] Herein, the provided distinguishing elements are only for clearly explaining each feature, and do not mean that the elements must be separated from each other. That is, a plurality of elements may be integrated into a single hardware or software unit. Moreover, a single element may be distributed into a plurality of hardware or software units. Thus, unless otherwise specifically described, integrated or distributed examples are also included within the scope of the present disclosure.

[0065] Herein, the elements described in various examples may not be essential and may be partially optional. Thus, 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.

[0066] The description herein relates to a wireless communication network, and the operations performed in the wireless communication network may be performed in the processing of controlling the network and transmitting data by a system (e.g., a base station) that controls the wireless network, or may be performed in a user equipment.

[0067] Obviously, in a network including a base station and a plurality of network nodes, various operations performed for communicating with a UE may be performed by the base station or other network nodes other than the base station. Here, the term "base station (BS)" may be used interchangeably with other terms, e.g., fixed station, Node B, eNodeB (eNB), gNodeB (gNB), and access point (AP). In addition, the term "terminal" may be used interchangeably with other terms, e.g., user equipment (UE), mobile station (MS), mobile subscriber station (MSS), subscriber station (SS), and non-AP station (non-AP STA).

[0068] Herein, transmitting or receiving a channel includes the meaning of transmitting or receiving information or a signal through the corresponding channel. For example, transmitting a control channel means transmitting control information or a signal through the control channel. Similarly, transmitting a data channel means transmitting data information or a signal through the data channel.

[0069] 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.

[0070] The New Radio (NR) system supports various subcarrier spacings (SCSs) by considering various scenarios, service requirements, potential system compatibilities, etc. 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 a variety of 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).

[0071] Here, 5G mobile communication technology can be defined by including existing Advanced Long Term Evolution (LTE-A) systems as well as the above-mentioned NR system. That is, 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 specific systems.

[0072] First, the physical resource structure of the NR system to which the present disclosure is applied will be briefly described.

[0073] Figure 1 An example of an NR frame structure according to an example of the present invention is shown.

[0074] 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, κ = 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.

[0075] Referring to Figure 1 , the time structure of a 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 max 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.

[0076] 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.

[0077] [Equation 1]

[0078] T TA = (N TA + N TA,offset )T c

[0079] 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

[0080] Figure 2 Shows the NR resource structure to which the present disclosure can be applied.

[0081] 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.

[0082] 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.

[0083] [Equation 2]

[0084]

[0086] The digital parameter configuration can be configured differently to meet the various services and requirements of the NR system. For example, one subcarrier spacing (SCS) can be supported in the LTE / LTE-A system, but multiple SCSs can also be supported in the NR system.

[0087] The new digital parameter configuration of the NR system supporting 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.

[0088] Table 1 below shows an example of the digital parameters supported by the NR system.

[0089] [Table 1]

[0090] 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

[0091] 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.

[0092] 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.

[0093] Here, a normal time slot can be defined as the 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 a time segment such as an LTE subframe.

[0094] For example, in LTE, data can be transmitted based on a transmission time interval (TTI) as the unit time. The 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).

[0095] 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 non-slot standards, it is provided only as an example.

[0096] In addition, for example, the SCS corresponding to μ = 1 and 2 can be used in an unlicensed band of 6 GHz or less, and the SCS corresponding to μ = 3 and 4 can be used in an unlicensed band of 6 GHz or more. Here, for example, if μ = 4, it can be used for a synchronization signal block (SSB).

[0097] [Table 2]

[0098]

[0099] Table 2 shows the number of OFDM symbols for each time slot with 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.

[0100] [Table 3]

[0101]

[0102] 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.

[0103] 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.

[0104] [Table 4]

[0105] SCS Time Slots within 10 ms Time Slots within 10 ms Symbols within 10 ms 15 kHz 10 20 140 30 kHz 20 40 280 60 kHz 40 80 560 120 kHz 80 N / A 1120 240 kHz 160 N / A 2240 480 kHz 320 N / A 4480

[0107] 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.

[0108] 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.

[0109] 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 shown 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.

[0110] [Table 5]

[0111]

[0112] In addition, SA1 can support operation in various systems (such as LTE and NR) because Enhanced V2X (eV2X) supports the technologies for supporting the V2X services. 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.

[0113] 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.

[0114] Here, the NR V2X capabilities can be not limited to basically only supporting V2X services, and the V2X RAT to be used can be selected.

[0115] 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.

[0116] 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.

[0117] 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 64QAM, or 256QAM or URMCS LLC table), PSFCH overhead indicator information (a parameter for the PSSCH rate matching operation with the 2nd SCI), and at least one reserved bit.

[0118] Figure 3 Fig. shows the NR SL time slot structure to which the present disclosure can be applied.

[0119] Reference 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 exist 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 .

[0120] 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. PSCCH (the first SCI) uses the DMRS of 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, PSSCH DMRS is used to decode the second SCI.

[0121] 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.

[0122] 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).

[0123] In addition, NR V2X service quality (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 NR V2X services. Here, these requirements can be configured as shown in Table 6 below, and Table 7 can show the PC5 QoS for NR V2X.

[0124] 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 capabilities, QoS-related information, radio bearer configuration, and physical layer configuration.

[0125] [Table 6]

[0126]

[0127] [Table 7]

[0128] · 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.

[0130] 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, if the V2X UE performs SL communication based on multicast, whether to report HARQ feedback can be determined based on the distance between the Tx UE and the Rx UE.

[0131] When the V2X UE performs at least one of unicast and multicast transmissions, SL HARQ feedback can be enabled or disabled. Here, whether to enable / disable HARQ feedback can be determined 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.

[0132] In the case of multicast, whether to send HARQ feedback can be determined 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 an affirmative 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, 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 HARQ feedback corresponding to the PSSCH reception.

[0133] Here, the location 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 location information, and can operate as described above.

[0134] In addition, when performing unicast communication based on V2X, the case of enabling SL HARQ feedback can be considered. The Rx UE can generate and send HARQ ACK / NACK corresponding to the PSSCH according to whether the decoding of the corresponding transport block (TB) is successful.

[0135] Then, the NR SL resource allocation mode refers to the mode in which the base station schedules SL transmission resources. Here, the mode in which the base station schedules 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.

[0136] 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.

[0137] [Table 8]

[0138]

[0140] Figure 5 Shows 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.

[0141] 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 the 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 the resource pool indicated by the number of consecutive subchannels (the 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 the time resources (e.g., sl-TimeResource) is not established and cannot be used as an NR sidelink resource, the reserved time slots can indicate the remaining time slots.

[0142] Next, the case where the unlicensed band (unlicensed spectrum) is used for communication between the base station and the UE can be considered. For example, the communication scheme based on the unlicensed band can be a scheme of occupying the channel through competition and performing communication based on the occupied channel. Even for the 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 using the sidelink unlicensed band to configure the sidelink resource pool. 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.

[0143] For example, the sidelink communication resource pool can be configured based on time slot units, and the symbols for 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.

[0144] Figure 6The unlicensed bands of each region of NR sidelink communication to which the present disclosure can be applied are 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 bands of the 6 GHz band, but is not limited thereto.

[0145] For example, the unlicensed bands can be located below 1 GHz, 2.4 GHz, 5 GHz, 6 GHz, 37 GHz (only in the United States), and 60 GHz, but are 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.

[0146] 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.

[0147] Here, in most regions, 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 a band of 5470 MHz or higher, it is used in regions 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 regions, given as the Effective Isotropic Radiated Power (EIRP) value based on Table 9 below, and the maximum transmit power is restricted.

[0148] [Table 9]

[0149]

[0151] 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 with a maximum transmit power of 23 dBm.

[0152] 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.

[0153] 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 only 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.

[0154] In addition, for example, the minimum occupancy bandwidth can be the bandwidth control that needs to be minimally occupied when a 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 the allocation of resources for the PUSCH in a specific bandwidth in an interleaved form, but it is not limited to the corresponding embodiments.

[0155] 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 of 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.

[0156] 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.

[0157] Figure 9 shows a method for configuring guard bands in consideration of a shared frequency band (e.g., an unlicensed frequency band) within a cell to which the present disclosure can be applied.

[0158] Referring to Figure 9 , to support wideband 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 positions in the frequency. Here, each guard band can be defined as a 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 within a single carrier accordingly.

[0159] 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 situation described above], 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 the 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.

[0160] 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.

[0161] 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.

[0162] [Equation 3]

[0163]

[0164] [Equation 4]

[0165]

[0166] [Equation 5]

[0167]

[0169] 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. In addition, 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.

[0170] 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 . In addition, 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.

[0172] 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 , the 2.4 GHz band can be used for industrial, scientific, and medical (ISM), the 3.5 GHz band can be used for citizen broadband radio service (CBRS), and the band from 5 GHz to 7 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 power effective isotropic radiated power (EIRP), and dynamic frequency selection (DFS) requirements can be determined, but it can be not limited to a specific form.

[0173] 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), satellites (UNII - 5), broadcasting (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, the indoor can be determined as EIRP 30 dBm (AP) and 24 dBm (UE), and the outdoor can be determined as EIRP 36 dBm (AP) and 30 dBm (UE), but they can be not limited to a specific form.

[0174] 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.

[0175] 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 (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 (which indicates the resource position) within a sidelink bandwidth part (SL BWP), 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).

[0176] 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 the physical resource block (PRB) as the minimum unit for resource selection. 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. Additionally, 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, excluding the time slots containing the reserved time slot SSB. Moreover, 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. Also, 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.

[0177] In addition, the UE can receive data and perform decoding, and can send hybrid automatic repeat request (HARQ) feedback as a response based on the reception success status. For example, the UE can determine whether decoding fails by combining the initial transmission and retransmission. In the current wireless communication system (such as NR), both the downlink (DL) and the uplink (UL) use the asynchronous HARQ incremental redundancy (IR) method. The base station can provide the HARQ feedback timing configuration to the UE through radio resource control (RRC) messages, and can flexibly indicate the HARQ feedback timing through DCI.

[0178] Specifically, for example, the base station can indicate the transmission timing to the UE through DCI. For example, K0 within the DCI can indicate the interval between the DCI sent to the physical downlink control channel (PDCCH) and the DL data sent to the physical downlink shared channel (PDSCH). Additionally, K1 within the DCI can indicate the interval between the reception of PDSCH DL data and the UL HARQ feedback timing sent to the physical uplink control channel (PUCCH). Moreover, K2 within the DCI can indicate the interval between the reception of the PDCCH UL grant and the UL data sent to the physical uplink shared channel (PUSCH).

[0179] In addition, for example, even in sidelink communication, HARQ feedback operations can be considered. Specifically, the medium access control (MAC) entity of the UE can include at most one sidelink HARQ entity for sidelink shared channel (SL-SCH) transmission. The sidelink HARQ entity can maintain up to 16 sidelink processes. The sidelink process can be configured to enable the transmission of multiple MAC protocol data units (PDUs). For example, in resource allocation mode 2 where the UE directly determines the sidelink resources, the UE can configure up to four sidelink processes for the transmission of multiple MAC PDUs. In addition, sidelink grants delivered to the MAC entity and information related to the sidelink grants can be configured in association with the sidelink processes. Each sidelink process can be used to send a single transport block (TB).

[0180] As another example, sidelink discontinuous reception (DRX) operations can be considered. Here, the sidelink DRX HARQ round-trip time (RTT) timer (sl-drx-HARQ-RTT-Timer) can be configured as a sidelink process within the sidelink HARQ entity of the UE, and operations based on the sidelink HARQ round-trip time timer can be performed. The sidelink DRX HARQ RTT timer can be configured differently based on at least one of HARQ feedback disable / enable, the presence or absence of a physical sidelink feedback channel (PSFCH), the presence or absence of retransmission resources within the SCI, and the HARQ feedback method (e.g., ACK / NACK, NACK only).

[0181] Figure 12 The sidelink DRX HARQ RTT timer applied to the present disclosure is shown. For example, Figure 12 it can be the case where, in a resource pool where the PSFCH is configured, HARQ feedback is enabled with a HARQ feedback enable indicator set to a first value within the SCI, and no retransmission resources are indicated. However, this is merely a configuration for clarity of description and is not limited to the corresponding embodiments.

[0182] In Figure 12In the example, time slot 1210 may be a time slot in which PSFCH is configured, and time slot 2 1220 may be a time slot in which PSFCH is not configured. When the UE receives PSCCH and PSSCH in time slot 1 1210, the UE may send HARQ feedback in a sidelink time slot (time slot 3 1230) in which PSFCH is configured, which is two time slots later based on the configured sl-MinTimeGapPSFCH parameter. The UE may expect to receive a retransmission grant or a new grant based on HARQ feedback in the first time slot after PSFCH transmission, and therefore may perform operations based on a sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) which is a sidelink DRX timer configured by a higher layer parameter. For example, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) may refer to the minimum time before an assignment for HARQ retransmission is expected, and the UE may be in a sleep state during the corresponding time period. In addition, a sidelink DRX HARQ RTT timer (SL drx-HARQ-RTT-Timer) may be configured for each HARQ process. For example, for clarity of description, it is referred to as the sidelink DRX HARQ RTT timer below, but the sidelink DRX HARQ RTT timer performing the same function may also be represented by different names and may not be limited to a specific form. As another example, although the UE does not perform sidelink HARQ feedback transmission through UL transmission due to UL / SL prioritization, the UE may operate the sidelink DRX HARQ RTT timer (SL drx-HARQ-RTT-Timer) in the first time slot after the end of the PSFCH resource to receive a retransmission authorization.

[0183] For example, when retransmission resources are configured within the SCI, as a case where HARQ feedback is enabled within the resource pool in which the PSFCH is configured, the sidelink DRX HARQ RTT timer (SL drx-HARQ-RTT-Timer) can be derived through the subsequent retransmission resources within the SCI. As another example, when HARQ feedback is disabled and there are no retransmission resources within the SCI, the UE can perform a sidelink DRX HARQ RTT timer (SL drx-HARQ-RTT-Timer) operation after the PSFCH. On the other hand, when HARQ feedback is disabled and there are retransmission resources within the SCI, the UE can operate the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-timer) from the received PSSCH to the subsequent retransmission resources within the SCI, and this can reduce the power consumption of the UE.

[0184] Figure 13 A method for operating a sidelink timer in a resource pool to which the present disclosure is applied and in which PSFCH is not configured is shown. Refer to Figure 13 , a resource pool in which PSFCH is not configured can be considered. Since the UE does not perform HARQ feedback operations in the corresponding resource pool, the UE can operate a sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-timer) after a PSCCH 1310 indicated in the SCI. For example, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-timer) can be based on the start of a slot unit, and the timer length can be configured based on the slot unit. In addition, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) can operate differently depending on whether there are retransmission resources in the SCI. Specifically, for example, in the case where there are no retransmission resources in the SCI, the operation can be different depending on whether there are retransmission resources in the SCI. When there are no retransmission resources in the SCI, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) can operate regardless of HARQ feedback enable / disable. On the other hand, when there are retransmission resources in the SCI, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) can be set to the time from the PSSCH to the subsequent retransmission resources. As another example, two sidelink DRX HARQ RTT timer values (sl-drx-HARQ-RTT-Timer) can be set for the presence and absence of PSFCH in the resource pool, and the present disclosure is not limited to a specific embodiment.

[0185] Figure 14 A sidelink HARQ feedback operation applied to the present disclosure is shown. Refer to Figure 14 , when the Rx UE receives a PSSCH 1410 in slot n, the Rx UE can determine a PSFCH opportunity to perform HARQ feedback according to a configured higher layer parameter (e.g., sl-MinTimeGapPSFCH). Specifically, for example, in Figure 14 , as a higher layer parameter, sl-MinTimeGapPSFCH can be configured with three slots. The UE can perform HARQ feedback in a first PSFCH opportunity 1430 that appears after slot n + 3, which is three slots from slot n. Specifically, for example, a case where the PSFCHS period is set to 4 in the resource pool can be considered. However, this is only an example for clarity of description, and the present disclosure is not limited thereto. The PSFCH opportunity can be configured for every four sidelink slots based on the PSFCH period 4. In Figure 14In [description], when the UE receives the PSSCH 1410 in time slot n, the UE can perform HARQ feedback in time slot n+5, where the first PSFCH occasion 1430 occurs after sl-MinTimeGapPSFCH.

[0186] Figure 15 FIG. [figure number] shows the PSSCH-PSFCH mapping applied to the present disclosure for HARQ feedback transmission. Refer to Figure 15 , the sidelink HARQ feedback resources may not be explicitly indicated and may be implicitly configured. The UE can derive the PSSCH and PSFCH association relationship based on pre-configured higher layer parameters, and can perform HARQ feedback through the PSFCH resources associated with the received PSSCH. Specifically, for example, in Figure 15 , the number of subchannels (N subch ,sl-NumSubchannel) within the resource pool is 4, and the PSFCH occasions can be configured for every four time slots according to sl-PSFCH-period. Here, the number of PSSCH time slots associated with a single PSFCH occasion can be 4. However, this is only an example for clarity of description and is not limited to the corresponding embodiments.

[0187] The UE can perform PSFCH resource mapping according to the PSSCH through configuration parameters. In addition, the physical resource blocks (PRBs) within the PSFCH occasion for HARQ feedback can be indicated as 0 or 1 as a bit string. For example, in Figure 15 , the total number of PRBs within the PSFCH occasion for HARQ feedback can be 80. Here, the 80 PRBs for HARQ feedback can represent the PRBs indicated as 1 in a bit string from 10 to 270 bits. Based on Equation 6 below, the 80 PRBs within a PSFCH occasion for HARQ feedback can be assigned to the time slots and subchannels associated with the PSFCH.

[0188] [Equation 6]

[0189]

[0191] Here, represents the time slot number associated with the PSFCH, and j((0≤j<N subch ) represents the subchannel number. In addition, represents by dividing the number of PRBs for HARQ feedback The value obtained by dividing by the number of subchannels and the number of time slots associated with the PSFCH. That is, for each subchannel of the time slot associated with the PSFCH To assign for HARQ feedback within the PSFCH occasion For example, in Figure 15 If the number of time slots associated with the PSFCH is four and there are four subchannels, there can be 16 subchannels. Here, if the number of PRBs for HARQ feedback Is 80, then five for each subchannel can be For HARQ feedback.

[0192] The UE selects the resources for transmitting HARQ feedback within the PSFCH PRB associated with the subchannel. Specifically, in Each PRB has two cyclic shift (CS) pairs And when sl-PSFCH-CandidateResourceType is set to The number of PSFCH candidate resources associated with a specific subchannel can be derived as shown in Equation 7.

[0193] [Equation 7]

[0194]

[0196] Here, Can be 20, and the numbers of the 20 candidate resources can be determined according to the CS order after PRB ascending order. The UE can select the PSFCH resources according to the index derived from Equation 8 below. As another example, when sl-PSFCH-CandidateResourceType is set to The number of PSFCH candidate resources can be configured differently.

[0197] [Equation 8]

[0198]

[0200] Here, P ID Represents the physical layer source ID indicated by the SCI format 2-A / 2-B / 2-C, and M ID Represents the higher layer UE ID for multicast HARQ ACK-NACK feedback. For example, in the case of unicast or multicast HARQ only NACK, M ID Can be 0.

[0202] In addition, for example, a UE may perform a Listen Before Talk (LBT) process for channel occupancy in an unlicensed band. The LBT process may be a process of determining whether a channel is occupied through a Clear Channel Assessment (CCA) check before using the channel. The CCA check may be an operation of performing sensing during a CCA period. The CCA check may use Energy Detection (ED) to detect whether there is another signal in the channel. Specifically, if the energy detected during the CCA period (e.g., received signal strength, Received Signal Strength Indicator (RSSI)) is less than the ED threshold, the UE may determine that the channel is not occupied and may occupy the channel during the COT. On the other hand, if the energy detected during the CCA period is greater than the ED threshold, the UE may determine that the channel is occupied, and the CCA period may be extended until the channel is unoccupied. For example, LBT may be a mandatory process for 5 GHz and 60 GHz unlicensed band operations in Europe and Japan, and may not be defined as a basic process in the United States and China. The CCA slot duration may be 9 μs at 5 GHz and 5 μs at 60 GHz, but is not limited thereto. More specifically, the initial CCA may be set to a multiple of 5 μs at 60 GHz, the extended CCA may be set to 8 + m × 5 μs, and m may be configured as a backoff counter. In addition, the ED threshold for a 20 MHz channel bandwidth may be set to -72 dBm at 5 GHz and may be set to -47 dBm at 60 GHz, but is not limited thereto.

[0203] In addition, for example, the LBT categories may consider Categories 1 to 4 shown in Table 10 below, but are not limited thereto.

[0204] [Table 10]

[0205]

[0206] Here, the UE can use different categories according to the transmission purpose. For example, the UE and the base station can use Cat 4 LBT for data transmission purposes in Licensed-Assisted Access (LAA). On the other hand, when the base station sends a discovery reference signal, Cat 2 LBT can be used. As another example, in NR-U, if the transmission interval between DL and UL in the COT sharing operation is less than 16 μs when the base station occupies the channel, the UE can perform Cat 1 LBT without CCA checking. On the other hand, if the transmission interval between DL and UL is greater than 16 μs and less than 25 μs, the UE can perform Cat 2 LBT using short sensing. In addition, if the transmission interval between DL and UL is greater than 25 μs, the UE can perform Cat 4 LBT for general data transmission. Here, although LAA can support one DL / UL exchange, NR-U can support multiple DL / UL handovers.

[0208] In addition, for example, continuous transmission may be restricted in the unlicensed band in a specific region (e.g., Europe, Japan). That is, the Maximum Channel Occupation Time (MCOT), which is the time for which the UE can continuously use the channel, may be limited. For example, according to the priority level in the 5 GHz band, the MCOT can be restricted to 2 ms, 4 ms, or 6 ms. In addition, the MCOT can be restricted to 9 ms in the 60 GHz band, but it is not limited thereto. In addition, for example, the UE and the base station can share the COT in the 5 GHz and 60 GHz bands. That is, downlink (DL) and uplink (UL) transmissions are possible within the COT. Specifically, when the base station occupies the channel through the LBT process and performs DL transmission to the UE, the UE can immediately perform UL transmission without CCA checking.

[0209] After successful LBT, the UE can occupy the channel and use the channel within the MCOT. Here, due to the flexible time slot structure such as micro time slots, compared with existing wireless communication systems (e.g., LTE), the current wireless communication system (e.g., NR) may perform transmission and reception operations in the unlicensed band inefficiently. Therefore, the COT can be shared between the base station and the UE, and the UE can improve the spectral efficiency or can perform a fast response operation.

[0210] Figure 16 The COT structure applied to the present disclosure is shown. For example, the wireless communication system can support a single DL / UL handover or multiple DL / UL handovers. Specifically, for example, referring to Figure 16For (a), a single DL / UL switch can be a configuration for performing a single DL / UL switch within the COT. Due to the small guard band, a single DL / UL switch can reduce overhead. If the interval between DL and UL is greater than 16 μs, multiple LBT procedures may not be performed. However, in a single DL / UL switch, after a specific period after DL, the UL operation is only configured once, so delays in HARQ feedback and UL scheduling may occur. For example, even if an attempt is made to perform Cat 4 LBT and it fails during the UL operation, a UL scheduling delay may occur. Considering the above, the single DL / UL switch COT configuration can be applicable to enhanced mobile broadband (eMBB) services with high throughput and flexible latency requirements, but is not limited thereto.

[0211] In addition, for example, referring to Figure 16 For (b), a multi-DL / UL switch COT configuration can be configured with multiple opportunities to perform UL. Therefore, in a multi-DL / UL switch COT configuration, the HARQ feedback configuration can be simple. In the case of performing sensing according to UL transmission LBT (i.e., if the interval between UL and DL is greater than 16 μs), the multi-DL / UL switch COT configuration can ensure channel utilization. Since the base station performs a CCA check for DL transmission, if the LBT is performed at a relatively close time, the LBT can be successful. However, since the multi-DL / UL switch COT configuration includes multiple guard bands, multiple LBT procedures may need to be performed. Considering the above, the multi-DL / UL switch COT configuration can be applicable to massive machine type communication (mMTC) with latency-sensitive services and low-load services, such as ultra-reliable low-latency communication (URLLC) or enhanced V2X (eV2X), but is not limited thereto.

[0212] In addition, for example, to limit interference between inter-RAT and intra-RAT in unlicensed band operation, power (EIRP, PSD) can be limited in all regions and bands, as described above.

[0213] In addition, for example, the occupied channel bandwidth (OCB) can be defined as the bandwidth that includes 99% of the signal power in a specific region. This can indicate that most of the channel bandwidth needs to be used when accessing a channel in the unlicensed band. For example, at 5 GHz, the OCB can be 70% to 100% of the nominal channel bandwidth (NCB), and at 60 GHz, the OCB can be 80% to 100% of the NCB, but is not limited thereto.

[0214] In addition, as an unlicensed band scenario, Licensed-Assisted Access (LAA), existing unlicensed band communication (LTE-unlicensed), and multi fire technology can be defined for operation in the 5 GHz band. However, current unlicensed band communication (LTE-unlicensed) can be designed by considering multiple frequency bands, such as 2.4 GHz, 3.5 GHz, 5 GHz, 6 GHz, 37 GHz, and 60 GHz, but not limited thereto. In addition, for example, the unlicensed band can be divided into a band of 7 GHz or less and a mmWave band. 7 GHz can include 2.4, 3.5, 5, and 6 GHz, and the mmWave band can include 37 GHz and 60 GHz, but not limited thereto.

[0216] Figure 17 A method for detecting a consistent LBT failure applicable to the present disclosure is shown. In a wireless communication system (e.g., NR), a UE can perform LBT in an unlicensed band. Referring to Figure 17 , the UE can detect an LBT failure. Before performing a transmission, the physical layer of the UE can perform an LBT process, and if the LBT is successful, the UE can occupy the channel and can perform the transmission. On the contrary, if the LBT fails during the LBT process, the UE can not occupy the channel and can not perform the transmission. Here, when the UE does not occupy the channel based on the LBT failure, the physical layer of the UE can deliver an LBT failure indication 1710 to the MAC layer of the UE. The MAC layer of the UE can be configured with a consistent LBT failure recovery process through higher layer signaling (e.g., RRC). For example, the UE can count and detect the consistent LBT failure for each uplink bandwidth part (UL BWP).

[0217] In addition, the UE can be configured with an LBT failure instance maximum counter (lbt-FailureInstanceMaxCounter) and an LBT failure detection timer (lbt-FailureDetectionTimer) through higher layer signaling. The UE can be configured with an LBT counter (LBT_COUNTER) as a UE variable through higher layer signaling, and the LBT counter counts the LBT failures for each serving cell.

[0218] Specifically, for example, referring to Figure 17(a), when the MAC layer of the UE receives a LBT failure indication 1710 from the physical layer of the UE, the MAC layer of the UE may increment the LBT counter (LBT_COUNTER) and may (re)start the LBT failure detection timer (lbt-FailureDetectionTimer). Here, if the LBT failure detection timer (lbt-FailureDetectionTimer) expires, the UE may initialize the LBT counter (LBT_COUNTER) to 0. In addition, referring to Figure 17 (b), when the LBT counter (LBT_COUNTER) is equal to or greater than the LBT failure instance maximum counter (lbt-FailureInstanceMaxCounter), the UE may generate a consistent LBT failure. For example, when the serving cell in which the consistent LBT failure is triggered is a special cell (SpCell) and the consistent LBT failure is triggered in all UL BWPs that configure physical random access channel (PRACH) opportunities in the carrier of the corresponding serving cell, the UE may indicate the consistent LBT failure to a higher layer. For example, when the consistent LBT failure is not triggered in a UL BWP that configures one or more PRACH opportunities, the UE may suspend the ongoing random access to the serving cell and may perform random access by configuring a PRACH opportunity in the enabled UL BWP and by switching the UL BWP in which the consistent LBT failure is not triggered.

[0219] Similarly, for example, for an SpCell, the consistent LBT failure may be triggered and may not be cancelled. When the MAC layer of the UE has uplink shared channel (UL-SCH) resources for a new transmission and includes a LBT failure MAC CE and a sub-header (which depends on the logical channel prioritization (LCP) result), the multiplexing and assembly process may be instructed to generate the LBT failure MAC CE. For example, an SpCell may represent a PCell. In addition, in the case of a dual connectivity (DC) connection, an SpCell may represent the PCell of the master cell group (MCG) and the PSCell of the secondary cell group (SCG). In addition, for example, a serving cell may represent a PCell, a PSCell, or an SCell.

[0220] In addition, for example, the case where a consistent LBT failure is triggered for at least one SCell and is not cancelled can be considered. Here, when the MAC layer of the UE has UL-SCH resources for new transmissions and may include an LBT failure MAC CE and a sub-header, the MAC layer may indicate the multiplexing and assembly process to generate the LBT failure MAC CE. Otherwise, the MAC layer of the UE may perform a scheduling request (SR) process to send the LBT failure MAC CE. In addition, for example, when a consistent LBT failure is triggered for the SpCell and random access is successfully performed after switching to another UL BWP, the MAC layer of the UE may cancel all triggered consistent LBT failures. In addition, when the MAC layer of the UE does not receive an LBT failure related to the transmission of a MAC protocol data unit (PDU) including an LBT failure MAC CE from the physical layer, the MAC layer of the UE may cancel all consistent LBT failures triggered for the SCell included in the LBT failure MAC CE. For example, Figure 18 shows an LBT failure MAC CE applied to the present disclosure. Refer to Figure 18 , C i in which i can represent the index of the serving cell (ServCellIndex). Here, the field of the serving cell where a consistent LBT failure is triggered may be set to 1, and other fields may be set to 0.

[0221] For example, sidelink communication may support improved V2X applications. In addition, sidelink communication may support proximity-based public safety and commercial services, but is not limited thereto. Sidelink communication may support operations to improve power consumption in the UE to increase data reliability by utilizing limited battery power and partial sensing, discontinuous reception (DRX), and inter-UE coordinated operations, but may not be limited thereto.

[0222] In addition, operations considering an increased data rate (increased sidelink data rate) in sidelink communication can be performed. For example, the increased data rate can be used to share sensor information of big data, such as video, between vehicles performing autonomous driving at a high level. The data rate can be increased based on methods such as sidelink carrier aggregation or using an unlicensed sidelink band, but the corresponding embodiments are not limited thereto. In addition, operations considering supporting a new carrier frequency for sidelink communication can be considered. Through FR2 sidelink operations with a new frequency and wide bandwidth, the data rate can be increased. For example, currently, the use of the intelligent transportation system (ITS) band may be limited to applications associated with ITS security. However, if operations such as using an unlicensed band are supported in sidelink communication, commercial services can be expected to be realized as the performance improves. In addition, for example, a V2X scenario in which LTE V2X and NR V2X UEs share the same frequency channel can be considered. A method for different types of UEs to effectively perform resource allocation without adversely affecting each other may be required, but the method is not limited thereto.

[0223] Next, a consistent LBT failure operation according to an unlicensed sidelink band (SL-U) is described in consideration of the above. For example, a UE can perform an LBT process in the SL-U and can perform a sidelink transmission according to the LBT success. On the other hand, if the UE performs an LBT process in the SL-U and does not occupy a channel due to an LBT failure, the UE may not perform a sidelink transmission. The above consistent LBT failure statement and recovery operation are described below.

[0224] For example, a UE can perform a consistent LBT failure detection and recovery process by considering an unlicensed band. The UE can perform an LBT process in the unlicensed band, and if the LBT is successful, it can occupy the channel and perform a transmission. On the contrary, if the LBT fails in the unlicensed band, the UE may not occupy the channel and may not perform a transmission. Also, if the LBT consistently fails, the UE may not occupy the channel and may not perform a transmission. In addition, if the LBT consistently fails, the UE can perform a BWP switch and an LBT failure MAC CE reporting process, and through this process, an LBT failure recovery operation can be performed. In the unlicensed band of a wireless communication system, the LBT failure detection unit can be a UL BWP. Here, for example, different from the unlicensed band of a wireless communication system, a resource pool can exist in the unlicensed sidelink band (SL-U). In addition, the SL-U can have a resource structure different from that of a wireless communication system. Considering the above, the LBT detection unit can be set differently from the unlicensed band of a wireless communication system in the SL-U, and based on this, an operation can be performed after a consistent LBT failure.

[0225] Specifically, for example, the LBT failure detection unit may consider at least one of the RB set (LBT bandwidth), resource pool, SL carrier, and BWP. For example, in SL-U, the UE may perform LBT based on the RB set and may perform channel access and occupancy. Here, the SL carrier may include multiple RB sets. For example, since the SL BWP is set to one, it may not be suitable as a consistent LBT failure detection unit, but this is not limitative. Considering the above, the consistent LBT failure detection unit may be set based on the resource pool or RB set, and the related description is given below.

[0226] The physical layer of the UE may occupy the channel only at specific time points based on the success of LBT in the unlicensed band and may continuously attempt channel access to the occupied specific channel (e.g., RB set). Here, the consistent LBT failure may be a situation where the LBT failure is triggered consistently. That is, the channel (e.g., RB set or resource pool) where the consistent LBT failure is triggered may indicate that it is difficult to occupy the channel due to high load and that another channel needs to be attempted for channel access.

[0227] Here, for example, in the mode where the UE directly performs scheduling, the mode 2 UE may detect the consistent LBT failure based on the set consistent LBT failure detection unit and may perform operations based on this. In addition, in the mode where the base station schedules the sidelink communication resources, the UE may perform a consistent LBT failure report to the base station for consistent LBT failure recovery, and the related description is given below.

[0228] For example, the detection of the consistent LBT failure may be performed based on the RB set or the resource pool, as shown in Table 11 below. Specifically, for example, in Table 11, as the case of detecting the consistent LBT failure based on the RB set, if the resource pool includes multiple RB sets and no consistent LBT failure is detected from at least one RB set, resource reselection may be performed. On the other hand, as the case of detecting the consistent LBT failure based on the RB set, if the resource pool includes a single RB set and a consistent LBT failure is detected from the corresponding RB set, resource pool reselection may be performed. As another example, as the case of detecting the consistent LBT failure based on the resource pool, if the SL BWP includes a resource pool where the consistent LBT failure is not triggered and a consistent LBT failure is detected from the set, resource pool reselection may be performed.

[0229] [Table 11]

[0230]

[0232] For example, a single SL BWP can be configured for a UE, and multiple resource pools can be configured for the configured SL BWP. In addition, the resource pool can include at least one set of RBs, and the set of RBs can be a unit for performing LBT.

[0233] Here, as shown in Table 11 above, in the case where consistent LBT failures are detected for each set of RBs, the MAC layer of the UE can select a resource pool and can select multiple resources divided into time and frequency resources based on the number of single / multiple MAC PDUs and HARQ retransmissions. In addition, the MAC layer of the UE can continuously perform Tx resource (re)selection check operations until the resources of the selected resource pool are released by a higher layer or the generation of the SL grant selected for multiple MAC PDUs is cancelled. The Tx resource (re)selection check can be a process for determining whether to maintain the use and reservation of the resources selected from the resource pool based on at least one of the following cases: the case where the physical sidelink control channel (PSCCH) of the selected SL grant and the PSSCH of the second sidelink control information (SCI) are not the sidelink enabled time at the destination UE; the case where the sidelink resource reselection counter (SL_RESOURCE_RESELECTION_COUNTER) becomes 0; the case where the resources of the resource pool are (re)configured by higher layer signaling; and the case where more than a predetermined number of resources indicated by the selected SL grant are not continuously used. For example, if the above conditions are met, all selected SL grants associated with the sidelink process are released, and a process of performing Tx resource (re)selection and assigning a new selected SL grant to the selected resource pool through new resource selection and reservation is performed.

[0234] In addition, for example, when consistent LBT failures are detected based on a set of RBs, if a set of RBs in which no consistent LBT failure is triggered is included in the selected resource pool, resource selection can be performed. Specifically, for example, the MAC layer of the UE can select resources from the resource pool based on a single MAC PDU or multiple MAC PDUs, can generate the selected SL grant, and can associate it with the sidelink process. In an unlicensed band, the UE can perform an LBT operation before performing a transmission, and if an LBT failure is continuously triggered, a consistent LBT failure can be triggered in the corresponding set of RBs in which the LBT is performed. Therefore, in the case where the UE may no longer maintain the resources selected from the resource pool, if there is a set of RBs in the resource pool in which no consistent LBT failure is triggered, the UE can perform resource selection from the corresponding set of RBs.

[0235] That is to say, the UE can select resources for a single MAC PDU / multiple MAC PDUs, can generate the selected SL grant, and can associate the selected SL grant with the sidelink grant.

[0236] Figure 19 Fig. shows a RB set-based consistent LBT failure detection method applicable to the present disclosure. Refer to Figure 19 , the SLBWP may include two RB sets 1910 and 1920, and the resource pool 1930 may include all two RB sets 1910 and 1920. However, this is only an example for clarity of description and is not limited thereto. The MAC layer of the UE may select the resource pool 0 1930. The MAC layer of the UE may select multiple resources divided into time and frequency based on a single / multiple MAC PDUs and the number of HARQ retransmissions. Here, the MAC layer of the UE may continuously perform the Tx resource (re)selection check operation until the resources of the selected resource pool are released by higher layer signaling or the generation of the SL grant selected for multiple MAC PDUs is cancelled. The physical layer of the UE may perform the LBT operation before transmitting the selected SL grant using the selected resources. Here, the LBT operation may be performed based on the RB set. When the UE performs the LBT operation and the LBT failure is continuously triggered in a specific RB set, a consistent LBT failure may be triggered. For example, in Figure 19 , although the consistent LBT failure may be triggered in the RB set 0 1910, this is only a configuration for clarity of description and the present disclosure is not limited thereto.

[0237] For example, when a consistent LBT failure is triggered in RB set 0 1910, the MAC layer of the UE can perform different operations depending on whether the selected resource pool includes multiple RB sets and whether there is an RB set in which a consistent LBT failure has not been triggered. Specifically, for example, resource pool 1930 includes multiple RB sets 1910 and 1920, and when there is an RB set in which a consistent LBT failure has not been triggered, the MAC layer of the UE can release the selected SL grant associated with the sidelink procedure through the Tx resource (re) selection check procedure and can perform the operation of checking the Tx resource (re) selection. The MAC layer of the UE can select multiple resources divided into time and frequency through the Tx resource (re) selection procedure based on the number of single / multiple MAC PDUs and HARQ retransmissions. Here, an operation of selecting resources within an RB set in which a consistent LBT failure has not been triggered may be required. For example, the MAC layer of the UE can perform resource selection by considering whether a consistent LBT failure has been triggered in the candidate resource set delivered by the physical layer of the UE. That is, the MAC layer of the UE can perform resource selection by separately considering whether a consistent LBT failure has been triggered, and the existing operations of the physical layer do not affect it, so it can be the same.

[0238] As another example, when the MAC layer of the UE selects resources from the candidate resource set delivered by the physical layer of the UE, the MAC layer of the UE can deliver the RB set information in which a consistent LBT failure has been triggered to the physical layer of the UE. The physical layer of the UE can configure the candidate resource set by excluding the resources within the RB set in which a consistent LBT failure has been triggered from the candidate resource set and can deliver the candidate resource set to the MAC layer of the UE. In the above case, the MAC layer of the UE can perform resource selection from the candidate resource set as described above.

[0239] Figure 20 A method for the MAC layer of a UE to select resources within a resource pool based on a consistent LBT failure applicable to the present disclosure is shown. For example, the SL BWP can include two RB sets (RB set 0 and RB set 1), and the resource pool can include two RB sets. That is, the MAC layer of the UE can select a specific resource pool including all of RB set 0 and RB set 1.

[0240] For example, when a consistent LBT failure is detected from an unlicensed band based on an RB set, the MAC layer of the UE can perform a Tx resource (re) selection check. The MAC layer of the UE can release the selected SL grant for the selected and reserved resources and can select multiple resources divided into time and frequency based on the number of single / multiple MAC PDUs and HARQ retransmissions. Specifically, refer to Figure 20(a), if a consensus LBT failure is triggered in RB set 0 2010, the MAC layer of the UE may generate a (re)selection of Tx resources and may reselect resources according to a sensing-based resource selection method. Here, the MAC layer of the UE may select resources within RB set (RB set 1) 2020, where the RB set (RB set 1) 2020 is an RB set in which a consensus LBT failure is not triggered in the candidate resource set (S A , set A).

[0241] As another example, referring to Figure 20 (b), if a consensus LBT failure is triggered in RB set 0 2010, the MAC layer of the UE may generate a (re)selection of Tx resources and may newly select resources according to a random-based resource selection method. Here, the MAC layer of the UE may select resources within RB set (RB set 1) 2020, where the RB set (RB set 1) 2020 is an RB set in which a consensus LBT failure is not triggered in the candidate resource set (S A , set A).

[0242] In addition, for example, if there is no RB set in the resource pool in which a consensus LBT failure is not triggered, the MAC layer of the UE may perform a process of selecting another resource pool including an RB set in which a consensus LBT failure is not triggered in the SL BWP.

[0243] Figure 21 shows a method for detecting a consensus LBT failure based on an RB set applicable to the present disclosure. Referring to Figure 21, in mode 2 where the UE directly selects sidelink communication resources, the MAC layer of the UE can determine to generate a single / multiple MAC PDUs and can perform operations based on this. The MAC layer of the UE can select a resource pool and can select a single resource for the initial transmission or retransmission opportunity (step 1, S2110). For example, the resource pool may include at least one set of RBs. Then, the MAC layer of the UE can verify whether a consistent LBT failure is triggered in a specific set of RBs within the resource pool (step 2, S2120). If a consistent LBT failure is not triggered, the MAC layer of the UE can continuously verify whether a consistent LBT failure is triggered in the specific set of RBs. On the contrary, when a consistent LBT failure is triggered in a specific set of RBs, the MAC layer of the UE can verify whether there is a resource set in which a consistent LBT failure is not triggered (step 3, S2130). For example, when there is no set of RBs in which a consistent LBT failure is not triggered in a specific set of RBs, the MAC layer of the UE can perform the resource pool and resource selection process again. On the contrary, when there is at least one set of RBs in which a consistent LBT failure is not triggered in a specific set of RBs, the MAC layer of the UE can perform the Tx resource (re)selection operation (step 4, S2140). Since there is a set of RBs in which a consistent LBT failure is not triggered in the resource pool, the MAC layer of the UE can release one or more resources selected through the resource pool and resource selection process as in step 1, and can newly select at least one resource from the corresponding set of RBs. Then, the MAC layer of the UE can select a resource within at least one set of RBs in which a consistent LBT failure is not triggered as the newly selected at least one resource (step 5, S2150).

[0244] Figure 22 shows a method for determining a candidate resource set based on a consistent LBT failure applicable to the present disclosure. Refer to Figure 22 , the physical layer of the UE can determine a candidate resource set by considering a consistent LBT failure. For example, the physical layer of the UE can receive a request from a higher layer and can determine an available candidate resource set within the resource pool indicated by the received request. Then, the physical layer of the UE can report the determined candidate resource set to the higher layer.

[0245] Here, when a coherent LBT failure is detected based on the RB set, the corresponding RB set may not be used until the coherent LBT failure is recovered. Therefore, the physical layer of the UE needs to report information about the new candidate resource set to the higher layer. Specifically, for example, the MAC layer of the UE may detect a coherent LBT failure from the RB set 0 2210, and then may request from the physical layer of the UE a resource set that can be determined for PSCCH / PSSCH transmission. For example, the MAC layer of the UE may deliver to the physical layer of the UE at least one RB set information in which the coherent LBT failure is triggered. Then, the physical layer of the UE may perform a process of excluding the resources reserved by another SCI within the selection window, and may exclude the resources in which the coherent LBT failure is triggered.

[0246] For example, in Figure 22 , the physical layer of the UE may determine a candidate resource set 2230 within n+T1 to n+T2. The candidate resource set 2230 may be determined as a resource that excludes the resources 2240 excluded by the SCI received within n+T1 to n+T2 and the resources 2250 within the RB set in which the coherent LBT failure is triggered. Here, n may be the time point when the MAC layer of the UE provides a parameter for requesting the candidate resource set, and the physical layer of the UE may finally determine the candidate resource set 2230 and may report it to the MAC layer of the UE. When the MAC layer of the UE selects the selected authorized resources, the MAC layer of the UE may select the resources in the candidate resource set 2230 reported by the physical layer without considering the coherent LBT failure.

[0247] As another example, consider the case of performing consistent LBT failure detection based on a resource pool. The MAC layer of the UE can select multiple resources divided into time and frequency based on a single / multiple MAC PDUs and the number of HARQ retransmissions. Here, the MAC layer of the UE can continuously perform Tx resource (re)selection check operations until the resources of the selected resource pool are released by higher layer signaling or the generation of the SL grant selected for multiple MAC PDUs is cancelled. The Tx resource (re)selection check can be a process of determining whether to maintain the use and reservation of the resources selected from the resource pool based on at least one of the following cases: the case where the PSCCH of the selected SL grant and the PSSCH of the second SCK are not the SL enabled time at the destination UE; the case where the side link resource reselection counter (SL_RESOURCE_RESELECTION_COUNTER) becomes 0; the case where the resources of the resource pool are (re)configured by higher layer signaling; and the case where more than a predetermined number of resources indicated by the selected SL grant are not continuously used. For example, if the above conditions are met, all the selected SL grants associated with the side link process are released, and if the Tx resources meet this condition, all the SL grant resources associated with the side link process can be released. Then, the MAC layer of the UE can perform Tx resource (re)selection and assign the newly selected SL grant to the selected resource pool through new resource selection and reservation.

[0248] In addition, for example, when a consistent LBT failure is detected based on a resource pool, the UE can perform an operation of switching from the frequency resources within the SL BWP to another resource pool that partially overlaps or does not completely overlap. Specifically, for example, the MAC layer of the UE can select a resource pool, can generate a single / multiple MAC PDU resources, can generate the selected SL grant, and can associate it with the side link process. The UE can perform the LBT operation before performing the transmission in the unlicensed band, and if the LBT failure is consistently triggered, the consistent LBT failure can be triggered in the corresponding resource pool. The UE can determine that the UE no longer holds the selected resources in the selected resource pool and can select a new resource pool. Therefore, the UE can select resources for a single / multiple MAC PDUs, can generate the newly selected SL grant, and can associate it with the side link process.

[0249] Figure 23 Shows the case where consistent LBT failure is performed based on a resource pool applicable to the present disclosure. Refer to Figure 23, the MAC layer of the UE can receive a set of candidate resources from the physical layer of the UE. The MAC layer of the UE can select Resource Pool 2 based on the set of candidate resources, can select resources for initial transmission or retransmission in the selected Resource Pool 2 by considering single / multiple MAC PDUs, can generate the selected SL grant in the corresponding resources, and can associate it with the sidelink procedure. Here, when a consistent LBT failure is triggered in Resource Pool 2, the UE can select Resource Pool 0 or Resource Pool 1 that partially overlaps or does not overlap at all with Resource Pool 2 within the SL BWP. Then, the UE can send the set of candidate resources for initial transmission or retransmission to the physical layer considering single / multiple MAC PDUs, can select resources based on this, can generate the selected SL grant in the corresponding resources, and can associate it with the sidelink process.

[0250] Figure 24 illustrates resource pool selection operations applicable to the present disclosure. Refer to Figure 24 , the UE may need to select a resource pool in which no consistent LBT failure is triggered. For example, when a consistent LBT failure is detected based on the resource pool, a consistent LBT failure may be detected from Resource Pool 12410 and Resource Pool 3 2430. However, this is only a configuration for the purpose of clear description and may not be limited thereto. Here, the MAC layer of the UE can select one of Resource Pool 2 2420 and Resource Pool 4 2440 in which no consistent LBT failure is triggered.

[0251] Figure 25 illustrates a method for detecting a consistent LBT failure based on a resource pool applicable to the present disclosure. Refer to Figure 25 , the MAC layer of the UE operating in Mode 2 (in which the UE directly selects sidelink communication resources by itself) can determine to generate single / multiple MAC PDUs and can perform operations based on this.

[0252] The MAC layer of the UE can select a resource pool and can select a single resource for the initial transmission or retransmission opportunity (Step 1, S2510). For example, the MAC layer of the UE can select a resource pool in which no consistent LBT failure is triggered. Specifically, for example, the MAC layer of the UE can select a specific resource pool according to whether PSFCH is configured in the resource pool where no consistent LBT failure is triggered, which is different from selecting a resource pool according to whether PSFCH is configured in the case of HARQ feedback enabled / disabled considering the data generated in the LCH.

[0253] Then, the MAC layer of the UE can verify whether a consensus LBT failure has been triggered in the selected resource pool (step 2, S2520). If a consensus LBT failure has not been triggered, the MAC layer of the UE can continuously verify whether a consensus LBT failure has been triggered in the selected resource pool. On the contrary, when a consensus LBT failure is triggered in the selected specific resource pool, the MAC layer of the UE can verify whether there is a resource pool in the SL BWP in which a consensus LBT failure has not been triggered (step 3, S2530). For example, when there is at least one resource pool in the SL BWP in which a consensus LBT failure has not been triggered, the MAC layer of the UE can continue the resource pool and resource selection process again. On the contrary, when there is no resource pool in the SL BWP in which a consensus LBT failure has not been triggered, the UE can disconnect the PC5-RRC connection by generating an SL radio link failure (RLF) because there is no resource pool to select in the SL BWP (step 4, S2540).

[0254] As another example, the operation of step 4 can be replaced by another operation. When there is no resource pool in the SL BWP in which a consensus LBT failure has not been triggered, an SL RLF may not be generated. Specifically, for example, in the case where carrier aggregation operation is enabled in the UE, if there is no resource pool in the SL BWP of a specific carrier in which a consensus LBT failure has not been triggered, the UE can report the consensus LBT failure triggered in the specific carrier to other carriers, and the SL BWP of the specific carrier can be configured differently.

[0255] For example, as described above, consensus LBT failure detection can be performed based on an RB set or a resource pool. Here, the UE can perform a consensus LBT failure report for consensus LBT failure recovery. Specifically, for example, a mode 1 UE controlled by a base station can send an SL LBT failure MAC CE to the base station. In addition, when a mode 2 UE that controls sidelink communication performs communication based on SL carrier aggregation, the UE can send an SL LBT failure MAC CE through another enabled SL carrier.

[0256] Figure 26 An SL LBT failure MAC CE applicable to the present disclosure is shown. Referring to Figure 26 (a) of, the MAC CE fixed to a single octet may include eight C fields. Here, C i can be set based on the unit for detecting a consensus LBT failure. Specifically, for example, when detecting a consensus LBT failure based on an RB set, C can be indicated by an RB set index i, and based on this, the presence or absence of a consistent LBT failure can be indicated. For example, if eight RB sets are included in the SL BWP and a consistent LBT failure is triggered in RB set 1, RB set 3, and RB set 5, that is, if eight RB sets are included and a consistent LBT failure is triggered in RB sets 1, 3, and 5, the C1, C3, and C5 fields can be set to 1 and the remaining C fields can be set to 0.

[0257] As another example, when detecting a consistent LBT failure on the basis of a resource pool, C i can be indicated by a resource pool index, and based on this, the presence or absence of a consistent LBT failure can be indicated. Specifically, for example, when five resource pools are configured within the SL BWP and a consistent LBT failure is triggered in resource pool 0 and resource pool 1, the C0 and C1 fields can be set to 1, and the remaining C fields can be set to 0.

[0258] As another example, referring to Figure 26 of (b), the MAC CE can be in a fixed form including four octets and can include 32 C fields. Therefore, when the number of RB sets or the number of resource pools is configured to be greater than 8, the MAC CE can be used. For example, SL carrier aggregation can use multiple SL carriers, and based on this, the number of used RB sets or resource pools can be increased. Considering the above, the MAC CE can be configured to have four octets, but it is not limited to the corresponding embodiments.

[0259] For example, the index of the C field can be configured by a higher layer for each RB set or resource pool. Specifically, for example, as a case of detecting a consistent LBT failure based on an RB set, the case where the SL BWP including four RB sets is enabled in SL carrier 1 and SL carrier 2 can be considered. However, this is only an example for clear description and is not limited thereto. Here, the four RB sets of SL carrier 1 can correspond to the C field indexes C0 to C3. In addition, in SL carrier 2, the four RB sets can correspond to the C field indexes C4 to C7.

[0260] As another example, as a case of detecting a consistent LBT failure based on a resource pool, the case where the SL BWP including four resource pools is enabled in SL carrier 1 and SL carrier 2 can be considered. Here, the four resource pools of SL carrier 1 can correspond to the C field indexes C0 to C3. In addition, in SL carrier 2, the four resource pools can correspond to the C field indexes C4 to C7.

[0261] Figure 27 shows an SL LBT failure MAC CE applicable to the present disclosure considering SL carrier aggregation. Referring to Figure 27 , andFigure 26 Differently, for each octet within the MAC CE, it may include a 2-bit ID and a 6-bit C field. Here, the ID may be the SL BWP ID or the SL carrier ID, but is not limited thereto. Specifically, for example, in the case of performing carrier aggregation through two SL carriers, the number of enabled carriers or SL BWPs may be two. Therefore, the ID may be indicated by one bit to distinguish between the two SL carriers or SL BWPs. As another example, in the case of performing carrier aggregation through four SL carriers, the number of enabled carriers or SL BWPs may be four. Therefore, the ID may be represented by 2 bits to distinguish between the four SL carriers or SL BWPs.

[0262] For example, the ID existing before the C field within one octet may be used to identify the RB set or resource pool and perform consistent LBT failure reporting. Specifically, for example, referring to Figure 27 (a) of, the MAC CE may be fixed to 1 octet. As another example, referring to Figure 27 (b) of, the MAC CE may be fixed to 4 octets. As another example, referring to Figure 27 (c) of, the MAC CE may be variably configured based on the number (N) of SL carriers or SL BWPs to be distinguished and is not limited to a specific form.

[0263] In addition, for example, although the ID is described above as the SL carrier ID or the SL BWP ID, it is not limited thereto and may be an ID for distinguishing multiple SL carriers. As another example, although the ID includes 2 bits, the ID may include more bits and is not limited thereto. For example, in the case of distinguishing multiple SL carriers or SL BWPs, the number of ID bits may increase. As another example, the number of C fields may not be limited to six within one octet and may be configured to be more and is not limited to a specific form.

[0264] Figure 28 Illustrates the SL LBT failure MAC CE reporting operation to which the present disclosure can be applied. Referring to Figure 28 , UE12810 may receive scheduling from the base station 2820 through the downlink control information (DCI) format 3_0. As another example, UE12810 may receive scheduling from UE2 2820 through the sidelink control information (SCI) format 1-A. Specifically, for example, when UE1 2810 operates in mode 1 in which the sidelink communication is controlled by the base station 2820, UE1 2810 may receive the DCI format 3_0 to receive PSCCH / PSSCH scheduling. Here, UE1 2810 may perform the LBT operation before performing transmission based on the unlicensed band. Referring to Figure 28, when the LBT fails to reach a preset threshold before UE1 2810 transmits the scheduled resources, UE1 2810 can trigger a sidelink (SL) compliant LBT failure. For example, as described above, the SL compliant LBT failure detection unit can be an RB set or a resource pool. UE1 2810 can report the compliant LBT failure to the base station 2820 based on the LBT failure detection unit. Here, the newly received resource pool or PSCCH / PSSCH resources indicated by DCI format 3_0 by the UE may not include the resources within the resource pool or RB set reported through the SL LBT failure MAC CE.

[0265] As another example, when UE2 2820 operates in mode 2 for controlling sidelink communication, UE1 2810 can receive SCI format 1-A from UE2 2820 acting as the Tx UE, and based on this, can receive the scheduling of PSSCH and the second SCI. For example, when HARQ feedback is enabled, UE1 2810 acting as the Rx UE may need to perform an LBT process before transmitting the PSFCH. Here, when the LBT failure reaches a predetermined threshold, UE1 2810 can trigger a SL compliant LBT failure. For example, as described above, the SL compliant LBT failure detection unit can be an RB set or a resource pool. UE1 2810 can report the compliant LBT failure to UE2 2820 through the SL LBT failure MAC CE based on the LBT failure detection unit. Then, UE2 2820 can send SCI format 1-A without selecting the resources within the RB set or resource pool reported from UE1 2810.

[0266] As another example, when UE1 2810 operates in mode 2 for controlling sidelink communication, UE1 2810 can become the Tx UE and can perform the scheduling of PSSCH and the second SCI to UE2 2820 through SCI format 1-A. As another example, UE1 2810 can perform an LBT process before performing SL transmissions (e.g., S-SSB, SCI), and can detect an LBT failure. Here, when the LBT failure reaches a predetermined threshold, UE1 2810 can trigger a SL compliant LBT failure. For example, as described above, the SL compliant LBT failure detection unit can be an RB set or a resource pool. UE1 2810 can report the compliant LBT failure to UE2 2820 through the SL LBT failure MAC CE based on the LBT failure detection unit. Then, UE2 2820 can send SCI format 1-A without selecting the resources within the RB set or resource pool reported from UE1 2810. In addition, UE2 2820 can identify that no SCI format 1-A transmission from UE1 2810 has been performed within the resources within the resource pool or RB set reported through the SL LBT failure MAC CE, and can not monitor the PSCCH within the corresponding resource pool.

[0267] Figure 29 shows a method for transmitting an SL LBT failure MAC CE applicable to the present disclosure. Referring to Figure 29 , the UE may perform LBT before performing SL transmission (step 1, S2910). For example, the UE may perform LBT by considering the unlicensed frequency band before performing an SL transmission scheduled by the base station or before scheduling time and frequency resources by the UE itself. Here, in the case of LBT failure (step 2, S2920), if the energy level received in a specific time interval is lower than the threshold, the UE may determine that the LBT is successful and may initialize the SL LBT counter to 0. On the contrary, if the energy level received in a specific time interval is higher than or equal to the threshold, the UE may determine that the LBT has failed and may increment the SL LBT counter (S2930). Here, for example, the MAC layer of the UE may increment the SL LBT counter each time based on the LBT failure. If the maximum counter value is reached based on the increment of the SL LBT counter (step 4, S2940), an SL consistent LBT failure may be triggered. For example, if the SL LBT counter becomes greater than the maximum counter which is a set threshold, the UE may generate an SL consistent LBT failure and may transmit an SL LBT failure MAC CE (step 5, S2950). For example, due to an SL consistent LBT failure detected based on an RB set or a resource pool, the UE may send an SL LBT failure MAC CE to the base station or another UE. For example, when the Tx UE operates in mode 1, the UE may send an SL LBT failure MAC CE to the base station and at least one Rx UE. On the other hand, when the Tx UE operates in mode 2, the UE may send an SL LBT failure MAC CE to at least one Rx UE. On the contrary, if the SL LBT counter is less than the maximum counter which is a set threshold, the UE may perform the process of step 1, that is, perform LBT for another SL transmission.

[0268] Figure 30It is a flowchart showing a method for performing sidelink communication based on a consistent LBT failure applied to the present disclosure. A wireless UE may select a resource pool and resources for sidelink communication based on a resource pool and a resource selection process (S3010). Then, the wireless UE may perform an LBT process using the resource pool and resources selected based on the sidelink unlicensed frequency band (S3020), and may verify a consistent LBT failure trigger status based on the LBT process (S3030). When a consistent LBT failure is triggered, the wireless UE may select resources for sidelink communication based on a transmission resource selection process (S3040). Here, the consistent LBT failure trigger status may be verified for each RB set, and the resource pool may include multiple RB sets. For example, when a consistent LBT failure is triggered in a first RB set among multiple RB sets included in the resource pool and a consistent LBT failure is not triggered in a second RB set among multiple RB sets included in the resource pool, the wireless UE may perform a resource selection process in the second RB set and may select resources for sidelink communication.

[0269] As another example, when a consistent LBT failure is triggered in the first RB set and a consistent LBT failure is not triggered in the second RB set, the MAC layer of the wireless UE may release the sidelink grant selected based on the resource selection process, and may select resources for sidelink communication included in the second RB set.

[0270] As another example, when a consistent LBT failure is triggered in the first RB set and a consistent LBT failure is not triggered in the second RB set, the MAC layer of the wireless UE may deliver the consistent LBT failure information to the physical layer of the wireless UE. The physical layer of the wireless UE may determine a candidate resource set based on the consistent LBT failure information and may deliver it to the MAC layer of the wireless UE. As described above, the MAC layer of the wireless UE may select at least one resource from the candidate resource set as the resource for sidelink communication.

[0271] As another example, the consistent LBT failure trigger status may be verified for each resource pool, and a single sidelink bandwidth part (SL BWP) may include multiple resource pools. For example, when a consistent LBT failure is triggered in a first resource pool among multiple resource pools included in the SL BWP and a consistent LBT failure is not triggered in a second resource pool among multiple resource pools included in the SL BWP, the wireless UE may select the second resource pool based on the resource pool and the resource selection process, and may perform a resource selection process in the second resource pool and select resources for sidelink communication. As another example, when a consistent LBT failure is triggered in all multiple resource pools included in the SL BWP, the wireless UE may release the connection with another wireless UE based on the SL RLF.

[0272] As another example, consistent LBT failure reporting can be performed by the SL LBT failure MAC CE, and each C field of the SL LBT failure MAC CE can be configured based on the consistent LBT failure reporting unit.

[0273] Figure 31 FIG. is a diagram showing a base station device and a terminal device to which the present disclosure can be applied.

[0274] The base station device 3100 may include a processor 3120, an antenna unit 3112, a transceiver 3114, and a memory 3116.

[0275] The processor 3120 performs baseband-related signal processing and may include a higher layer processor 3130 and a physical layer processor 3140. The higher layer processor 3130 may handle operations of the medium access control (MAC) layer, the radio resource control (RRC) layer, or higher layers thereof. The physical layer processor 3140 may handle operations of the physical (PHY) layer (e.g., uplink received signal processing, downlink transmitted signal processing). In addition to performing baseband-related signal processing, the processor 3120 may also control the operation of the base station device 3100.

[0276] The antenna unit 3112 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.

[0277] The memory 3116 may store information that has been computationally processed in relation to the operation of the base station device 3100, such as software, an operating system, applications, etc. of the processor 3120, and may include components such as buffers.

[0278] The processor 3120 of the base station 3100 may be configured to implement the operations of the base station in the examples described herein.

[0279] The terminal device 3150 may include a processor 3170, an antenna unit 3162, a transceiver 3164, and a memory 3166. For example, here, the terminal device 3150 may perform communication with the base station device 3100. As another example, here, the terminal device 3150 may perform SL communication with another terminal device. That is, the terminal device 3150 used herein refers to a device capable of communicating with at least one of the base station device 3100 and other terminal devices, and is not limited to communicating with a specific device.

[0280] The processor 3170 performs baseband-related signal processing and may include a higher layer processor 3180 and a physical layer processor 3190. The higher layer processor 3180 may handle operations of the MAC layer, RRC layer, or higher layers. The physical layer processor 3190 may handle operations of the PHY layer (e.g., downlink received signal processing, uplink transmitted signal processing). In addition, in addition to performing baseband-related signal processing, the processor 3170 may also control the operation of the terminal device 3150.

[0281] The antenna unit 3162 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.

[0282] The memory 3166 may store the information that has been computationally processed related to the operation of the base station device 3100 of the processor 3170, software, operating system, applications, etc., and may include components such as buffers.

[0283] The terminal device 3150 according to an example of the present disclosure may be associated with a vehicle. For example, the terminal device 3150 may be integrated in the vehicle, may be located in the vehicle, or may be located on the vehicle. In addition, the terminal device 3150 according to the present disclosure may be the vehicle itself. In addition, the terminal device 3150 according to the present disclosure may be at least one of a wearable terminal, AR / VR, Internet of Things (IoT) terminal, robot terminal, and public safety terminal. The terminal device 3150 to which the present disclosure may be applied may include various types of communication devices that support interactive services using sidelinks for services such as Internet access, service execution, navigation, real-time information, autonomous driving, and safety and risk diagnosis. In addition, the terminal device 3150 may include an AR / VR device capable of performing sidelink operations or any type of communication device capable of performing a relay operation as a sensor.

[0284] Here, the vehicles to which the present disclosure is applied may include autonomous vehicles, semi-autonomous vehicles, and non-autonomous vehicles. At the same time, although the terminal device 3150 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 disclosure.

[0285] In addition, the terminal device 3150 according to an example of the present disclosure may include various types of communication devices capable of performing cooperation to support interactive services using sidelinks. That is, the terminal device 3150 may directly support interactive services using sidelinks and may be used as a cooperation device for supporting interactive services using sidelinks.

[0286] In addition, for example, the terminal device 3150 may select a resource pool and resources for sidelink communication based on a resource pool and a resource selection process. Then, the terminal device 3150 may perform an LBT process using the selected resource pool and resources based on the sidelink unlicensed band, and may verify a consistent LBT failure trigger status based on the LBT process. When a consistent LBT failure is triggered, the terminal device 3150 may select resources for sidelink communication based on a transmission resource selection process. Here, the consistent LBT failure trigger status may be verified for each RB set, and the resource pool may include multiple RB sets. For example, when a consistent LBT failure is triggered in a first RB set among multiple RB sets included in the resource pool and a consistent LBT failure is not triggered in a second RB set among multiple RB sets included in the resource pool, the terminal device 3150 may perform a resource selection process in the second RB set and may select resources for sidelink communication.

[0287] As another example, when a consistent LBT failure is triggered in a first RB set and a consistent LBT failure is not triggered in a second RB set, the MAC layer of the terminal device 3150 may release the sidelink authorization selected based on the resource selection process and may select resources for sidelink communication included in the second RB set.

[0288] As another example, when a consistent LBT failure is triggered in a first RB set and a consistent LBT failure is not triggered in a second RB set, the MAC layer of the terminal device 3150 may deliver the consistent LBT failure information to the physical layer of the terminal device 3150. The physical layer of the terminal device 315 may determine a candidate resource set based on the consistent LBT failure information and may pass it to the MAC layer of the terminal device 3150. As described above, the MAC layer of the terminal device 3150 may select at least one resource from the candidate resource set as a resource for sidelink communication.

[0289] As another example, the consistent LBT failure trigger status may be verified for each resource pool, and a single sidelink bandwidth part (SL BWP) may include multiple resource pools. For example, when a consistent LBT failure is triggered in a first resource pool among multiple resource pools included in the SL BWP and a consistent LBT failure is not triggered in a second resource pool among multiple resource pools included in the SL BWP, the terminal device 3150 may select the second resource pool based on the resource pool and the resource selection process, and may perform a resource selection process in the second resource pool and select resources for sidelink communication. As another example, when a consistent LBT failure is triggered in all multiple resource pools included in the SL BWP, the terminal device 3150 may release the connection with another wireless UE based on the SL RLF.

[0290] As another example, consistent LBT failure reporting can be performed via a SL LBT failure Medium Access Control (MAC) Control Element (CE), and each C field of the SL LBT failure MAC CE can be configured based on a consistent LBT failure reporting unit.

[0291] In addition, various embodiments of the present disclosure can be implemented by hardware, firmware, software, or a combination thereof. In the case of implementation by hardware, the embodiments 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, and the like.

[0292] The scope of the present disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) for enabling the operations of the methods according to various embodiments, and devices or non-transitory computer-readable media executable on a computer storing such software or instructions.

[0293] The various embodiments of the present disclosure are used to explain 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.

[0294] Industrial Applicability

[0295] The above can be applied to other systems.

Claims

1. A wireless user equipment (UE) that performs a listen - before - talk (LBT) operation in a sidelink unlicensed band in a wireless communication system, the wireless UE comprising: At least one antenna configured to transmit and receive one or more wireless signals; At least one processor; And A memory configured to store instructions for the wireless UE when executed by the at least one processor, Wherein the wireless UE is configured to, Based on a resource pool and a resource selection process, select a resource pool and resources for sidelink communication, Use the resource pool and the resources selected based on the sidelink unlicensed band to perform a listen - before - talk (LBT) process, Based on the LBT process, verify a consistent LBT failure trigger status, and When the consistent LBT failure is triggered, select the resources for the sidelink communication based on a transmission resource selection process.

2. The wireless UE according to claim 1, wherein, The consistent LBT failure trigger status is verified according to a set of resource blocks (RBs), The resource pool includes multiple sets of RBs, and When the consistent LBT failure is triggered in a first RB set among the multiple RB sets included in the resource pool and the consistent LBT failure is not triggered in a second RB set among the multiple RB sets included in the resource pool, the wireless UE performs a resource selection process in the second RB set and selects the resources for sidelink communication.

3. The wireless UE according to claim 2, wherein, When the consistent LBT failure is triggered in the first RB set and not triggered in the second RB set, the media access control (MAC) layer of the wireless UE releases the sidelink authorization selected based on the resource selection process and selects the resources for the sidelink communication included in the second RB set.

4. The wireless UE according to claim 2, wherein When the consistent LBT failure is triggered in the first RB set and not triggered in the second RB set, the MAC layer of the wireless UE delivers the consistent LBT failure information to the physical layer of the wireless UE. The physical layer of the wireless UE determines a candidate resource set based on the consistent LBT failure information and delivers it to the MAC layer of the wireless UE, and the MAC layer of the wireless UE selects at least one resource from the candidate resource set as the resources for the sidelink communication.

5. The wireless UE according to claim 1, wherein The consistent LBT failure trigger status is verified by resource pool, A single sidelink bandwidth part (SL BWP) includes multiple resource pools, and When the consistent LBT failure is triggered in a first resource pool among the multiple resource pools included in the SL BWP and the consistent LBT failure is not triggered in a second resource pool among the multiple resource pools included in the SL BWP, the wireless UE selects the second resource pool based on the resource pool and the resource selection process, and performs a resource selection process in the second resource pool and selects the resources for the sidelink communication.

6. The wireless UE according to claim 5, wherein, When the coherent LBT failure is triggered in all of the plurality of resource pools included in the SL BWP, the wireless UE releases the connection with another wireless UE based on a sidelink radio link failure (SL RLF).

7. The wireless UE according to claim 1, wherein, The coherent LBT failure report is performed by an SL LBT failure media access control (MAC) control element (CE), and each C field of the SL LBT failure MAC CE is configured based on a coherent LBT failure reporting unit.

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