METHOD AND APPARATUS FOR PERFORMING SIDELINK COMMUNICATION BASED ON LBT PROCEDURE OVER UNLICENSED SPECTRUM

Abstract

The operation of a wireless user device performing LBT in a sidelink unlicensed band in a wireless communication system is as follows: select a resource pool and resources for sidelink communication based on a resource pool and resource selection procedure, perform an LBT procedure on the resource pool and resources selected based on the sidelink unlicensed band, check whether consecutive LBT failures have occurred based on the LBT procedure, and if consecutive LBT failures have occurred, select resources for sidelink communication based on the transmission resource selection procedure.

Description

[Technical Field]

[0001] The present disclosure relates to a method and apparatus for performing sidelink communication based on a listen before talk (LBT) procedure over an unlicensed spectrum in a wireless communication system. Specifically, the present disclosure relates to a method and apparatus for performing sidelink communication based on consistent LBT failures. [Background technology]

[0002] The International Telecommunication Union (ITU) is developing the International Mobile Telecommunication (IMT) framework and standards, and recently discussions for fifth-generation (5G) communications have been underway through a program called "IMT for 2020 and beyond."

[0003] To meet the requirements set out in "IMT for 2020 and beyond," the 3GPP (registered trademark) 3rd Generation Partnership Project (NR) New Radio (NR) system is currently discussing the support of various numerologies for time-frequency resource unit standards, taking into account various scenarios, service requirements, potential system compatibility, etc.

[0004] In addition, 5G communication can support the transmission of physical signals or physical channels through multiple beams to overcome poor channel conditions such as high path loss, phase noise, and frequency offset that occur at high carrier frequencies. This enables 5G communication to support applications such as enhanced Mobile Broadband (eMBB), massive Machine Type Communications (mMTC), and Ultra Reliable and Low Latency Communication (URLLC).

[0005] V2X communication, a communication method for exchanging or sharing information such as traffic conditions while communicating with road infrastructure and other vehicles while driving, can also be considered. V2X can include vehicle-to-vehicle (V2V), which refers to Long Term Evolution (LTE) / New Radio (NR)-based communication between vehicles, vehicle-to-pedestrian (V2P), which refers to LTE / NR-based communication between vehicles and personally carried devices, and vehicle-to-infrastructure / network (V2I / N), which refers to LTE / NR-based communication between vehicles and roadside units / networks. Here, roadside units (RSUs) can be transportation infrastructure entities implemented by base stations or fixed devices. For example, they can be entities that transmit speed notifications to vehicles. Summary of the Invention [Problem to be solved by the invention]

[0006] The technical problem of the present disclosure relates to a method and apparatus for performing sidelink (SL) communication in a wireless communication system.

[0007] The technical problem of the present disclosure relates to a method and apparatus for performing sidelink communication based on an LBT procedure on an unlicensed spectrum in a wireless communication system.

[0008] The technical problem of the present disclosure relates to a method and apparatus for performing sidelink communication based on consecutive LBT failures on an unlicensed spectrum in a wireless communication system.

[0009] The technical problem of the present disclosure relates to a method and apparatus for performing sidelink communication based on successive LBT failure detection units.

[0010] The technical problems to be achieved by the present disclosure are not limited to the above-mentioned technical problems, and other technical problems not described can be clearly understood by a person having ordinary skill in the technical field to which the present disclosure pertains from the following description. [Means for solving the problem]

[0011] According to one aspect of the present disclosure, a wireless user device (UE) for LBT operation in a sidelink unlicensed band in a wireless communication system includes at least one antenna for transmitting and receiving one or more radio signals, at least one processor, and a memory for storing instructions for the wireless user device, when executed by the at least one processor, wherein the wireless user device operates to: select a resource pool and resources for sidelink communication based on a resource pool and resource selection procedure; perform a listen before talk (LBT) procedure on the resource pool and resources selected based on the sidelink unlicensed band; check whether consistent LBT failures have occurred based on the LBT procedure; and, if consistent LBT failures have occurred, select resources for sidelink communication based on the transmission resource selection procedure.

[0012] In addition, according to one aspect of the present disclosure, whether or not consecutive LBT failures have occurred is checked for each RB (resource block) set. If a resource pool includes multiple RB sets, and consecutive LBT failures have occurred in a first RB set among the multiple RB sets included in the resource pool, but consecutive LBT failures have not occurred in a second RB set among the multiple RB sets included in the resource pool, the wireless user equipment can perform a resource selection procedure in the second RB set to select resources for sidelink communication.

[0013] Furthermore, according to one aspect of the present disclosure, when consecutive LBT failures occur in the first RB set but consecutive LBT failures do not occur in the second RB set, the MAC (medium access control) layer of the wireless user equipment can release the sidelink grant selected based on the resource selection procedure and select resources for sidelink communication included in the second RB set.

[0014] Furthermore, according to one aspect of the present disclosure, when consecutive LBT failures occur in the first RB set but not in the second RB set, the MAC layer of the wireless user equipment transmits consecutive LBT failure information to the physical layer of the wireless user equipment, the physical layer of the wireless user equipment determines a candidate resource set based on the consecutive LBT failure information and transmits the determined candidate resource set to the MAC layer of the wireless user equipment, and the MAC layer of the wireless user equipment can select at least one resource from the candidate resource set as a resource for sidelink communication.

[0015] In addition, according to one aspect of the present disclosure, whether or not consecutive LBT failures have occurred is checked for each resource pool. One sidelink bandwidth part (SL BWP) includes multiple resource pools. If consecutive LBT failures have occurred in a first resource pool among the multiple resource pools included in the SL BWP and consecutive LBT failures have not occurred in a second resource pool among the multiple resource pools included in the SL BWP, the wireless user equipment may select a second resource pool based on the resource pool and the resource selection procedure, and perform the resource selection procedure in the second resource pool to select resources for sidelink communication.

[0016] Furthermore, according to one aspect of the present disclosure, if consecutive LBT failures occur in all of the resource pools included in the SL BWP, the wireless user equipment may disconnect from other wireless user equipment based on a sidelink radio link failure (SL RLF).

[0017] Furthermore, according to one aspect of the present disclosure, consecutive LBT failure reporting is performed through an SL LBT failure MAC CE (medium access control element), and the C field of each of the SL LBT failure MAC CEs can be set based on consecutive LBT failure reporting units. [Effects of the Invention]

[0018] According to the present disclosure, a method for performing sidelink (SL) communication in a wireless communication system can be provided.

[0019] According to the present disclosure, a method and apparatus for performing sidelink communication based on an LBT procedure over an unlicensed spectrum in a wireless communication system can be provided.

[0020] According to the present disclosure, a method and apparatus for performing sidelink communication based on consecutive LBT failures on an unlicensed spectrum of a wireless communication system can be provided.

[0021] According to the present disclosure, a method and apparatus for performing sidelink communication based on consecutive LBT failure detection units can be provided.

[0022] The effects obtained by the present disclosure are not limited to the effects described above, and other effects not mentioned will be clearly understood by those having ordinary skill in the art to which the present disclosure pertains from the following description. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram for explaining an NR frame structure to which the present disclosure can be applied. [Figure 2] FIG. 2 is a diagram illustrating an NR resource structure to which the present disclosure may be applied. [Figure 3] FIG. 3 is a diagram illustrating an NR sidelink slot structure to which the present disclosure can be applied. [Figure 4] FIG. 4 is a diagram illustrating NR sidelink frequencies to which the present disclosure can be applied. [Figure 5] FIG. 5 is a diagram illustrating an NR sidelink resource pool configuration to which the present disclosure can be applied. [Figure 6] FIG. 6 is a diagram illustrating unlicensed bands by region for NR sidelink communication to which the present disclosure can be applied. [Figure 7] FIG. 7 is a diagram illustrating 5 GHz unlicensed band usage to which the present disclosure may be applied. [Figure 8] FIG. 8 illustrates a method for increasing bandwidth taking into account PSD limitations to which the present disclosure may be applied. [Figure 9] FIG. 9 is a diagram showing a method for setting a guard band in consideration of a shared band within an intra-cell to which the present disclosure can be applied. [Figure 10] FIG. 10 is a diagram illustrating an unlicensed spectrum applicable to the present disclosure. [Figure 11]FIG. 11 is a diagram illustrating a sidelink resource pool to which the present disclosure can be applied. [Figure 12] FIG. 12 illustrates a sidelink DRX HARQ RTT timer applied to the present disclosure. [Figure 13] FIG. 13 is a diagram illustrating a method for operating a sidelink timer in a resource pool in which a PSFCH is not configured, which is applied to the present disclosure. [Figure 14] FIG. 14 illustrates a sidelink HARQ feedback operation applied to the present disclosure. [Figure 15] FIG. 15 is a diagram illustrating PSSCH-PSFCH mapping for HARQ feedback transmission applied to the present disclosure. [Figure 16] FIG. 16 is a diagram showing a COT structure applied to the present disclosure. [Figure 17] FIG. 17 illustrates a method for detecting consecutive LBT failures that can be applied to the present disclosure. [Figure 18] FIG. 18 is a diagram illustrating an LBT failure MAC CE applied to the present disclosure. [Figure 19] FIG. 19 is a diagram illustrating an RB set-based successive LBT failure detection method applied to the present disclosure. [Figure 20] FIG. 20 is a diagram illustrating a method in which a MAC layer of a terminal selects resources in a resource pool based on consecutive LBT failures, which is applied to the present disclosure. [Figure 21] FIG. 21 is a flowchart illustrating a method for detecting consecutive LBT failures in units of RB sets, which is applied to the present disclosure. [Figure 22] FIG. 22 is a diagram illustrating a method for determining candidate resource sets based on consecutive LBT failures that is applied to the present disclosure. [Figure 23] FIG. 23 is a diagram illustrating a case where successive LBT failures applied to the present disclosure are performed in resource pool units. [Figure 24] FIG. 24 is a diagram illustrating a resource pool selection operation applied to the present disclosure. [Figure 25]FIG. 25 is a diagram illustrating a method for detecting consecutive LBT failures in units of resource pools, which is applied to the present disclosure. [Figure 26] FIG. 26 is a diagram illustrating the SL LBT failure MAC CE applied to the present disclosure. [Figure 27] FIG. 27 is a diagram illustrating an SL LBT failure MAC CE taking into account SL carrier aggregation applied to the present disclosure. [Figure 28] FIG. 28 is a diagram illustrating an SL LBT failure MAC CE reporting operation applied to the present disclosure. [Figure 29] FIG. 29 is a diagram illustrating a method for transmitting an SL LBT failure MAC CE according to the present disclosure. [Figure 30] FIG. 30 is a flowchart illustrating a method for performing sidelink communication based on consecutive LBT failures according to the present disclosure. [Figure 31] FIG. 31 is a diagram showing a base station apparatus and a terminal apparatus to which the present disclosure can be applied. DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present disclosure will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily implement the present disclosure. However, the present disclosure may be embodied in various different forms and is not limited to the embodiments described herein.

[0025] In describing embodiments of the present disclosure, if it is determined that a detailed description of a known configuration or function would obscure the gist of the present disclosure, the detailed description will be omitted. In addition, in the drawings, parts that are not related to the description of the present disclosure will be omitted, and similar parts will be designated by similar reference numerals.

[0026] In this disclosure, when a component is said to be "coupled," "coupled," or "connected" to another component, this refers not only to a direct connection, but also to an indirect connection where there is another component between them. Furthermore, when a component is said to "include" or "have" another component, this does not exclude the other component, but means that the component may further include the other component, unless otherwise specified.

[0027] In this disclosure, terms such as first and second are used only to distinguish one component from another, and do not limit the order or importance of the components unless otherwise specified. Therefore, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0028] In this disclosure, components that are distinguished from one another are used to clearly describe the characteristics of each component and do not necessarily mean that the components are separate. That is, multiple components may be integrated into a single hardware or software unit, or a single component may be distributed into multiple hardware or software units. Therefore, even if not otherwise specified, such integrated or distributed embodiments are also included within the scope of this disclosure.

[0029] In this disclosure, the components described in various embodiments are not necessarily essential components, and some may be optional components. Therefore, an embodiment consisting of a subset of the components described in one embodiment is also included in the scope of this disclosure. Note that an embodiment including other components in addition to the components described in various embodiments is also included in the scope of this disclosure.

[0030] The present disclosure describes a wireless communication network, and operations performed in the wireless communication network may be performed in a process of controlling the network and transmitting or receiving signals by a system (e.g., a base station) that manages the wireless communication network, or in a process of transmitting or receiving signals by a terminal coupled to the wireless network.

[0031] It is apparent that various operations performed for communication with a terminal in a network consisting of multiple network nodes including a base station may be performed by the base station or other network nodes other than the base station. The term "base station (BS)" may be replaced with terms such as fixed station, Node B, eNodeB (eNB), ng-eNB, gNodeB (gNB), access point (AP), etc. Furthermore, the term "terminal" may be replaced with terms such as user equipment (UE), mobile station (MS), mobile subscriber station (MSS), subscriber station (SS), non-AP station (non-AP STA), etc.

[0032] In this disclosure, transmitting or receiving a channel includes transmitting or receiving information or signals through the channel. For example, transmitting a control channel means transmitting control information or signals through the control channel. Similarly, transmitting a data channel means transmitting data information or signals through the data channel.

[0033] In the following description, the term NR (New Radio) system is used to distinguish the system to which various examples of the present disclosure are applied from existing systems, but the scope of the present disclosure is not limited by these terms.

[0034] The NR system supports various subcarrier spacings (SCS) taking into account various scenarios, service requirements, and potential system compatibility. The NR system can also support the transmission of physical signals / channels through multiple beams to overcome adverse channel conditions such as high path loss, phase noise, and frequency offset that occur at high carrier frequencies. This allows the NR system to support applications such as enhanced Mobile Broadband (eMBB), massive Machine Type Communications (mMTC) / ultra Machine Type Communications (uMTC), and Ultra Reliable and Low Latency Communications (URLLC).

[0035] Hereinafter, 5G mobile communication technology may be defined to include not only the NR system but also the existing LTE-A (Long Term Evolution-Advanced) and LTE (Long Term Evolution) systems. That is, 5G communication may include not only the newly defined NR system but also technologies that operate in consideration of backward compatibility with previous systems. Therefore, the 5G mobile communication described below may include technologies that operate based on the NR system and technologies that operate based on previous systems (e.g., LTE-A, LTE), and is not limited to a specific system.

[0036] First, a brief description will be given of the physical resource structure of the NR system to which the present invention is applied.

[0037] FIG. 1 is a diagram for explaining an NR frame structure to which the present disclosure can be applied.

[0038] The basic unit of time domain in NR is T c =1 / (Δf max N f ) and Δf max =480 10 3 and N f = 4096, whereas the time domain base unit in LTE is Ts = 1 / (Δf ref N f,ref ) and Δf ref =15 10 3 and N f,ref = 2048. The constant for the multiple relationship between the base unit of NR time and the base unit of LTE time is κ = T s / T c =64.

[0039] Referring to FIG. 1, the time structure of a frame for downlink / uplink (DL / UL) transmission is T f =(Δf max N f / 100)·T s = 10 ms, where one frame is T sf =(Δf max N f / 1000)·T s The number of consecutive OFDM symbols in each subframe is N subframe,u symb =N slot symb N subframe,u slot Also, each frame can be divided into two half frames of the same size, with half frame 1 consisting of subframes 0 to 4 and half frame 2 consisting of subframes 5 to 9.

[0040] N TA denotes the timing advance (TA) between the downlink (DL) and the uplink (UL), where the transmission timing of the uplink transmission frame i is determined based on the downlink reception timing at the terminal according to the following Equation 1:

[0041]

number

[0042] where N TA,offset is the TA offset value that occurs due to differences in duplex modes. TA,offset has a value of 0, but in TDD (Time Division Duplex), N is set to N in consideration of the margin for DL-UL switching time. TA,offset For example, in TDD (Time Division Duplex) in FR1 (Frequency Range 1), which is a frequency below 6 GHz, N TA,offset is 39936T c or 25600T c It can be. 39936T c is 20.327μs, and 25600T c is 13.030μs. Also, at the millimeter wave (mmWave) frequency FR2 (Frequency Range 2), N TA,offset is 13792T c At this time, 39936T c is 7.020μs.

[0043] FIG. 2 is a diagram illustrating an NR resource structure to which the present disclosure may be applied.

[0044] The resource elements (REs) in the resource grid can be indexed by each subcarrier spacing, where one resource grid can be generated for each antenna port and each subcarrier spacing, and uplink and downlink transmission and reception can be performed based on the resource grid.

[0045] In the frequency domain, one resource block (RB) consists of 12 REs, and an index (n PRB ) can be configured. The index for the RB can be used within a specific frequency band or system bandwidth. The index for the RB can be defined as in Equation 2 below. Here, N RB sc denotes the number of subcarriers per RB, and k denotes the subcarrier index.

[0046]

number

[0047] Various neural networks can be configured to meet the various services and requirements of the NR system. For example, an LTE / LTE-A system can support one subcarrier spacing (SCS), while an NR system can support multiple SCSs.

[0048] New pneumatics for NR systems supporting multiple SCSs can operate in frequency ranges or carriers such as below 3 GHz, 3 GHz to 6 GHz, 6 GHz to 52.6 GHz, or above 52.6 GHz, solving the problem of not being able to use wide bandwidths in frequency ranges or carriers such as 700 MHz or 2 GHz.

[0049] Table 1 below shows examples of pneumoradio supported by the NR system.

[0050] [Table 1]

[0051] Referring to Table 1, the neural network parameters can be defined based on the subcarrier spacing (SCS), cyclic prefix (CP) length, and number of OFDM symbols per slot used in an Orthogonal Frequency Division Multiplexing (OFDM) system. These values ​​can be provided to the UE through upper layer parameters DL-BWP-mu and DL-BWP-cp for the downlink and through upper layer parameters UL-BWP-mu and UL-BWP-cp for the uplink.

[0052] In Table 1, when the subcarrier spacing setting index (u) is 2, the subcarrier spacing (Δf) is 60 kHz, and normal CP and extended CP can be applied. In other cases, only normal CP can be applied.

[0053] A normal slot can be defined as a basic time unit used to transmit one piece of data and control information in an NR system. The length of a normal slot can be basically set to 14 OFDM symbols. Furthermore, unlike a slot, a subframe has an absolute time length corresponding to 1 ms in an NR system and can be used as a reference time for the length of other time intervals. Here, for coexistence or backward compatibility between LTE and NR systems, a time interval similar to an LTE subframe may be required in the NR standard.

[0054] For example, in LTE, data may be transmitted based on a transmission time interval (TTI), which is a unit of time, and the TTI may be set in units of one or more subframes. Here, in LTE, one subframe may be set to 1 ms and may include 14 OFDM symbols (or 12 OFDM symbols).

[0055] Furthermore, non-slots can be defined in NR. A non-slot may refer to a slot having a number of symbols at least one smaller than that of a normal slot. For example, when providing low latency, such as in a URLLC service, the latency can be reduced by using a non-slot having a number of symbols smaller than that of a normal slot. Here, the number of OFDM symbols included in a non-slot can be determined taking into account the frequency range. For example, in a frequency range of 6 GHz or higher, a non-slot having a length of one OFDM symbol can be considered. As a further example, the number of OFDM symbols defining a non-slot can include at least two OFDM symbols. Here, the range of the number of OFDM symbols included in a non-slot can be set as the length of a mini-slot up to a predetermined length (e.g., the normal slot length minus 1). However, as a non-slot standard, the number of OFDM symbols may be limited to, but not limited to, 2, 4, or 7 symbols.

[0056] For example, in unlicensed bands below 6 GHz, subcarrier spacing where u is 1 and 2 can be used, and in unlicensed bands above 6 GHz, subcarrier spacing where u is 3 and 4 can be used. For example, when u is 4, it can be used for SSB (Synchronization Signal Block).

[0057] [Table 2]

[0058] Table 2 shows the number of OFDM symbols per slot (N) for normal CP, depending on the subcarrier spacing setting (u). slot symb ), number of slots per frame (N frame,u slot ), the number of slots per subframe (N subframe,u slot) Table 2 shows the above values ​​based on a normal slot having 14 OFDM symbols.

[0059] [Table 3]

[0060] Table 3 shows the number of slots per frame and the number of slots per subframe when extended CP is applied (i.e., when u is 2 and the subcarrier spacing is 60 kHz), based on a normal slot with 12 OFDM symbols per slot.

[0061] As mentioned above, one subframe may correspond to 1 ms on the time axis. Furthermore, one slot may correspond to 14 symbols on the time axis. For example, one slot may correspond to 7 symbols on the time axis. Therefore, the number of slots and symbols that can be considered within 10 ms, which corresponds to one radio frame, can be set differently. Table 4 shows the number of slots and symbols according to each SCS. In Table 4, the 480 kHz SCS may not be considered, but is not limited to these examples.

[0062] [Table 4]

[0063] V2X services (e.g., LTE Rel-14 V2X) can support basic requirements for V2X services. The requirements are primarily designed with road safety services in mind. Here, V2X User Equipment (UE) can exchange status information with each other through sidelink. Furthermore, V2X UE can exchange information with infrastructure nodes and / or pedestrians.

[0064] V2X services (e.g., LTE Rel-15) can support at least one of carrier aggregation, high order modulation, latency reduction, transmit diversity, and sTTI (Transmission Time Interval) in the sidelink. To this end, new features can be applied to V2X communication. Specifically, V2X UEs can operate while taking into account coexistence with other V2X UEs. For example, V2X UEs can use the same resource pool as other V2X UEs.

[0065] As an example, considering use cases for supporting V2X services in SA (System Aspect) 1, technical features can be classified into four categories as shown in Table 5 below, but are not limited to these. In Table 5, Vehicle Platooning can be a technology in which multiple vehicles dynamically form a group and operate in a similar manner. Extended Sensors can be a technology that collects and exchanges data obtained from sensors or video footage. Advanced Driving can be a technology in which vehicles drive based on full automation or semi-automation. Remote Driving can be a technology that provides technology and applications for remote control of vehicles, and more specific details of the above can be seen in Table 5 below.

[0066] [Table 5]

[0067] Furthermore, SA1 is an eV2X (enhanced V2X) support technology for supporting V2X services and can support cases where it operates in various systems (e.g., LTE, NR). As an example, a case can be considered in which the NR V2X system is a first V2X system and the LTE V2X system is a second V2X system. That is, the NR V2X system and the LTE V2X system can be different V2X systems.

[0068] Hereinafter, a method for achieving low latency and high reliability required for an NR sidelink will be described based on an NR V2X system. However, the same or similar configuration may be extended and applied to an LTE V2X system, and the present invention is not limited to the following embodiments. That is, the present invention may be applied to parts that are interoperable with an LTE V2X system.

[0069] Here, NR V2X capability is not necessarily limited to supporting only V2X services, and may optionally support the use of a certain V2X RAT.

[0070] Additionally, NR V2X services can additionally consider new service requirements for public safety and commercial use cases. For example, use cases may include, but are not limited to, at least one of more advanced V2X services, public safety services, NCIS (Network Controlled Interactive Service), MONASTERYEND (Gap Analysis for Railways), REFEC (Enhanced Relays for Energy eFficiency and Extensive Coverage), and AVPROD (Audio-Visual Service Production).

[0071] For the NR V2X, physical channels, signals, a basic slot structure, and physical resources can be configured. Here, the NR Physical Sidelink Shared Channel (NR PSSCH) can be a physical layer NR Sidelink (SL) data channel. V2X terminals can exchange data and control information (e.g., 2nd SCI, CSI) through the NR PSSCH. The NR Physical Sidelink Control Channel (NR PSCCH) is a physical layer NR SL control channel. The NR PSCCH is a channel for transmitting control information (1st SCI, Sidelink Control Information) including scheduling information for the NR SL data channel and a 2nd SCI indication. That is, a V2X terminal can transmit control information for sidelink data communication to another V2X terminal through the PSCCH. The NR Physical Sidelink Feedback Channel (NR PSFCH) is a channel for transmitting physical layer NR Hybrid Automatic Repeat Request (HARQ) feedback information and for transmitting HARQ-ACK feedback information corresponding to the NR SL data channel (i.e., PSSCH). After transmitting data to another V2X terminal, a V2X terminal can receive HARQ feedback information for the data via the NR PSFCH. The NR Sidelink Synchronization Signal / Physical Sidelink Broadcast Channel block (SLSS / PSBCH block) is a channel block in which an NR sidelink synchronization signal and a broadcast channel are transmitted over a continuous time period in the physical layer. Here, the SLSS / PSBCH block may be transmitted periodically based on a set of one or more block indexes to support beam-based transmission in the NR frequency band.The synchronization signal consists of a Primary Sidelink Synchronization Signal (PSSS) and a Secondary Sidelink Synchronization Signal (SSSS). The synchronization signal is generated in a sequence based on at least one SLSSID value. The NR Physical Sidelink Broadcast Channel (PSBCH) is a channel that carries system information required for V2X sidelink communication. The NR PSBCH is transmitted together with the SLSS and is periodically transmitted in the form of an aggregate of the SLSS / PSBCH block index to support beam-based transmission.

[0072] In addition, a physical sidelink control channel (PSCCH) and a physical sidelink shared channel (PSSCH) can be defined based on NR V2X. A terminal can transmit sidelink control information (SCI) to another terminal through the PSCCH. Here, a transmitting terminal can transmit a primary SCI (1st SCI, SCI format 1-A) to a receiving terminal through the PSSCH. In this case, the primary SCI can be used to schedule the PSSCH and the secondary SCI (2nd SCI) within the PSSCH, and the primary SCI can include at least one of priority information, time / frequency resource allocation information, resource reservation information, Demodulation Reference Signal (DMRS) pattern information, secondary SCI format indication information, beta-offset indicator information as a parameter for the secondary SCI and PSSCH rate matching operation, DMRS port number information, MCS (Modulation Coding Scheme) information, additional MCS table indicator information (e.g., indicating one of 64QAM, 256QAM, or URLLC MCS tables), PSFCH overhead indication information (a parameter for the 2nd SCI and PSSCH rate matching operation), and reserved bits.

[0073] FIG. 3 is a diagram illustrating an NR sidelink slot structure to which the present disclosure can be applied.

[0074] Referring to FIG. 3, one sidelink slot (SL slot) includes one automatic gain control (AGC) symbol. One SL slot also includes one transmit-receive (Tx-Rx) switching symbol. In one SL slot, the PSSCH, which is a channel for transmitting data, is transmitted through one or more subchannels (e.g., two subchannels in the case of FIG. 3). In addition, in the time domain, the remaining orthogonal frequency division multiplexing (OFDM) symbols, excluding the AGC symbol and the Tx-Rx switching symbol, may transmit the PSCCH (1st SCI), the secondary SCI, the PSSCH (Data), and a demodulation RS (DMRS) for demodulation. Specifically, the positions of the PSCCH (1st SCI), the secondary SCI, the PSSCH (Data), and the DMRS (Demodulation RS) for demodulation are as shown in FIG. 3, but are not limited thereto. For example, in Fig. 3, the first subchannel has a PSCCH and a secondary SCI, and the PSSCH and DMRS can be allocated taking this into consideration. As another example, the second subchannel in Fig. 3 is a subchannel without a PSCCH or a secondary SCI, and the PSSCH and DMRS can be allocated as shown in Fig. 3.

[0075] Here, the number of OFDMs for the PSSCH DMRS can be set to one or more depending on the channel environment of the terminal through higher layer configuration. The PSCCH (1st SCI) is decoded and received using the DMRS of the PSCCH (i.e., the PSCCH DMRS) and is transmitted by being evenly allocated to every four resource elements within one resource block (RB). On the other hand, the 2nd SCI is decoded using the PSSCH DMRS.

[0076] For example, one resource pool related to the NR sidelink can support all of frequency division multiplexing (FDM), time division multiplexing (TDM), and spatial division multiplexing (SDM). That is, each resource in one resource pool can be divided and used based on frequency, time, and space, thereby improving resource efficiency.

[0077] 4 is a diagram illustrating NR sidelink frequencies to which the present disclosure can be applied. For example, the NR sidelink can operate based on at least one of FR1 (Frequency Range 1, sub 6 GHz) and FR2 (Frequency Range 2, i.e., up to 52.6 GHz), unlicensed ITS bands, and licensed bands. As a specific example, referring to FIG. 4, 5,855 to 5,925 MHz can be allocated for ITS services (technology neutral manner).

[0078] Furthermore, NR V2X Quality of Service (QoS) requirements can be considered. That is, as requirements for NR V2X services, delay, reliability, and data rate must meet certain conditions. Here, the requirements can be set as shown in Table 6 below, and Table 7 can be a table showing PC5 QoS for NR V2X.

[0079] Here, to meet QoS requirements, access stratum (AS)-level QoS management may be necessary. For this purpose, HARQ and CSI feedback associated with link adaptation may be required. Furthermore, each NR V2X UE may have a different maximum bandwidth capability. In consideration of the above, NR V2X UEs may exchange AS-level information including at least one of UE capability, QoS-related information, radio bearer configuration, and physical layer configuration.

[0080] [Table 6]

[0081] [Table 7-1] [Table 7-2] [Table 7-3]

[0082] NOTE 1: For Standardized PQI to QoS characteristics mapping, the table will be extended / updated to support service requirements for other identified V2X services.

[0083] Next, the sidelink HARQ procedure will be described. Whether a V2X terminal reports HARQ feedback is indicated by higher layer (e.g., RRC) configuration and SCI signaling (e.g., 2nd SCI). For example, when a V2X terminal performs communication based on groupcast, it can determine whether to report HARQ feedback based on the distance between the transmitting terminal and the receiving terminal.

[0084] When a V2X terminal performs unicast and / or groupcast, it may enable or disable sidelink HARQ feedback, where the enable / disable of HARQ feedback may be determined based on at least one of channel conditions (e.g., RSRP), the distance between the transmitting terminal and the receiving terminal, and QoS requirements.

[0085] In the case of groupcast, whether to transmit HARQ feedback can be determined depending on the physical distance between the transmitting terminal and the receiving terminal. Here, when HARQ feedback is performed based on groupcast, the receiving terminal can operate to feed back a negative acknowledgment only when PSSCH decoding fails. This can be the operation of option 1. On the other hand, when HARQ feedback is performed based on groupcast, the receiving terminal can operate to feed back a positive or negative acknowledgment depending on whether PSSCH decoding is successful, which can be the operation of option 2. In the operation of option 1, which feeds back only a negative acknowledgment to the HARQ NACK based on groupcast, feedback for the PSSCH can be performed if the physical distance between the transmitting terminal and the receiving terminal is smaller than or equal to the communication range requirement. On the other hand, if the physical distance between the transmitting terminal and the receiving terminal is larger than the communication range requirement, the V2X terminal does not need to feed back PSSCH.

[0086] At this time, the location of the transmitting terminal is indicated to the receiving terminal through the SCI associated with the PSSCH. The receiving terminal can estimate the distance to the transmitting terminal based on the information included in the SCI and its own location information and operate as described above.

[0087] In addition, when performing unicast communication based on V2X, the case where sidelink HARQ feedback is enabled can be taken into consideration. The receiving terminal can generate and transmit HARQ ACK / NACK for PSSCH based on whether the corresponding TB (Transport Block) has been successfully decoded.

[0088] Next, the NR sidelink resource allocation mode includes a mode in which the base station schedules sidelink transmission resources. Here, the mode in which the base station schedules sidelink transmission resources may be Mode 1. For example, when a V2X terminal is located within the base station coverage, the V2X terminal may receive sidelink resource information from the base station based on Mode 1. On the other hand, there is also a mode in which the V2X terminal directly determines resources for sidelink transmission from sidelink resources configured by the base station / network or pre-configured sidelink resources. Here, the mode in which the terminal directly determines sidelink transmission resources may be Mode 2.

[0089] Also, the numerology and waveform for the sidelink may be considered, and may be as shown in Table 8 below. Specifically, in relation to the PSSCH / PSCCH and PSFCH in the sidelink, the SCS and CP lengths supported by each of FR1 and FR2 may be as shown in Table 8 below. Here, the waveform may not support DFT-S-OFDM and may support only OFDM, but is not limited thereto. A sidelink-synchronization signal block (SL-SSB) may be defined independently for each frequency range, which may be similar to NR-Uu.

[0090] [Table 8]

[0091] FIG. 5 is a diagram illustrating an NR sidelink resource pool configuration to which the present disclosure can be applied. Referring to FIG. 5, a resource pool may refer to time and frequency resources used for sidelink transmission and reception. As an example, at least one resource pool may be configured within one SL BWP within one carrier. Here, the resources of the resource pool may be configured based on time resources in units of slot sets and frequency resources in units of consecutive subchannel sets. Furthermore, the resource pool may be configured separately for transmission and reception.

[0092] More specifically, the time resource for resource pool configuration provided in the NR sidelink is the time period of the resource pool, a set of sidelink slots (sl-TimeResource(length=L bitmap)), the first symbol for a set of consecutive symbols within one slot, and / or the number of consecutive symbols may be configured. The frequency resource may be configured as at least one of the bandwidth of one subchannel (e.g., sl-SubchannelSize={10, 15, 20, 25, 50, 75, and 100} RBs), the total bandwidth of a resource pool indicated by the number of consecutive subchannels (a set of consecutive subchannels (e.g., sl-NumSubchannel={1 to 27}), and the frequency domain position of the first subchannel of the resource pool (sl-StartRBsubchannel={0 to 265}). For example, resources in the time domain and the frequency domain may be configured based on higher layer parameters. In FIG. 5, the frequency resource corresponding to the excluded resource block (RB) may refer to some RBs remaining when the total available RB resources do not exactly match the subchannel size (i.e., the number of RBs does not equal one subchannel). In this case, the resource may not be used in the NR sidelink. Also, for example, reserved slots (reserved slots) may be configured. The sl-slot) may refer to the remaining slots in a situation where a multiple of the length of the bitmap on the time resource (e.g., sl-TimeResource) is not established, and may not be used as an NR sidelink resource.

[0093] Next, a case where an unlicensed spectrum is used for communication between a base station and a terminal may be considered. For example, a communication scheme based on an unlicensed spectrum may occupy a channel through contention and perform communication based on the occupied channel. Communication based on an unlicensed spectrum may also be performed between a base station and a terminal. Hereinafter, an operation based on a case where an unlicensed spectrum is used for sidelink communication will be described. That is, an unlicensed spectrum may also be used in sidelink communication, which is communication between terminals. Furthermore, a sidelink resource pool needs to be configured taking into account the use of a sidelink unlicensed spectrum. More specifically, sidelink communication may be performed based on a resource pool, and if communication is performed through an unlicensed spectrum, the resource pool configuration needs to be different.

[0094] For example, the resource pool for sidelink communication may be configured on a slot-by-slot basis to determine symbols available for sidelink within a slot, as shown in Figure 5. In addition, in the frequency domain, the resource pool may be configured based on the number of consecutive subchannels, as shown in Figure 5. The sidelink resource pool configuration may be performed taking into account unlicensed band communication, as will be described later.

[0095] 6 is a diagram illustrating unlicensed bands by region for NR sidelink communication to which the present disclosure can be applied. In Table 8 above, the frequency range of R FR1 may be 450 MHz to 6 GHz, but the corresponding frequency range may be changed to 450 MHz to 7.125 GHz. The NR FR1 frequency range may be changed for the unlicensed band in the 6 GHz band, but is not limited to this.

[0096] By way of example, and without limitation, the unlicensed bands may be located below 1 GHz, 2.4 GHz, 5 GHz, 6 GHz, 37 GHz (US only), and 60 GHz. Referring to Figure 6, for example, the 5 GHz band in the system may be Band 46, defined as 5150-5925 MHz. Furthermore, by way of example, and without limitation, Band 49 (3550-3700 MHz) may be defined as a CBRS (citizens broadband radio service) band for LAA operations.

[0097] Figure 7 is a diagram illustrating the use of the 5 GHz unlicensed band to which the present disclosure can be applied. Referring to Figure 7, each band within the 5 GHz unlicensed band can be set, and the use of the unlicensed band can be set based on that band. For example, the bands can be divided into 20 MHz units for use, and each 20 MHz can be one channel.

[0098] In most areas, the low frequency band from 5150 to 5350 MHz is intended for indoor use and is regulated to have a maximum transmission power of 23 dBm. In the band above 5470 MHz, a transmission power of up to 30 dBm is permitted for outdoor use. In addition to the maximum transmission power limit, some areas may have additional requirements, such as the EIRP (effective isotropic radiated power) value shown in Table 9 below.

[0099] [Table 9]

[0100] Here, PSD (power spectral density) can mean that a device is limited to transmitting at full power within a reference bandwidth. As a specific example, European regulations may limit PSD to 10 dBm / MHz. Therefore, if the bandwidth is not 20 MHz, a device cannot transmit at a maximum transmission power of 23 dBm.

[0101] 8 is a diagram illustrating a method for increasing bandwidth in consideration of PSD limitations to which the present disclosure may be applied. As an example, consider the case of small data transmission, which requires only a small bandwidth, as shown in FIG. 8. In this case, if small data transmission is performed over a wide bandwidth, coverage can be expanded. Furthermore, transmission over a wide bandwidth can satisfy minimum bandwidth occupancy regulations. In consideration of the above, a method for transmitting small data over a wide bandwidth may be preferable.

[0102] For example, when a channel is occupied through a channel access procedure in an unlicensed band, the maximum channel occupancy time (COT), which corresponds to the maximum time that a channel can be occupied, can be set differently for each region. For example, Japan allows a maximum COT of 4 ms, while Europe allows a maximum COT of 8 ms or 10 ms. However, this is merely an example and is not limited to the above-described embodiment. For example, Europe can support Frame Based Equipment (FBE) and Load Based Equipment (LBE) rules. Here, FBE is set to High Performance Radio LAN (HiperLAN) / 2, and LBE can be adopted and applied in the Wi-Fi standard, and both can be supported in NR as a new communication system.

[0103] Further, as an example, the minimum occupied bandwidth may be a specification of a bandwidth that must be minimally occupied once a channel connection is successful. For example, the specification of the minimum occupied bandwidth may be set to occupy 80 to 90% or more of the nominal channel BW. As a specific example, when a terminal transmits a PUSCH to a base station in an unlicensed band, it may request that resources for the PUSCH be allocated to the entire band in an interlaced form with a specific bandwidth, but this may not be limited to this embodiment.

[0104] Furthermore, the dynamic frequency selection provision may be a provision to limit bandwidth usage in order to protect systems (e.g., radio) that have a high priority for using unlicensed bands. Furthermore, the transmit power control provision may be a provision to limit the use of transmit power lower than the maximum permitted transmit power value. Furthermore, the LBT (listen before talk) provision is a provision regarding procedures for channel access, and Europe can support FBE and LBE rules. At this time, FBE is Hiperlan / 2, and LBE can be adopted and applied in Wi-Fi standards, and both can be supported in NR.

[0105] For example, the 5 GHz unlicensed band can be used based on the above, but discussions regarding the use of the 6 GHz band are underway among various countries and organizations. Unlike the 5 GHz band, the 6 GHz band may be a band that has not yet been used by a mobile system. That is, unlike the 5 GHz band, which is shared by multiple mobile communication systems, the 6 GHz band can be used for a single, specific communication system. This reduces the problems and inefficiencies that arise from the coexistence of multiple different systems.

[0106] FIG. 9 is a diagram showing a method for setting a guard band in consideration of a shared band (e.g., an unlicensed band) within an intra-cell to which the present disclosure can be applied.

[0107] Referring to FIG. 9, to support wideband operation in shared spectrum access, the UE may receive an IntraCellGuardBandsPerSCS parameter for each uplink carrier (UL carrier) and downlink carrier (DL carrier) from the base station based on the base station configuration. The UE may receive N subcarrier spacing indexes (μ) on one carrier. RB-set,x A terminal may be provided with an intra-cell guard band of -1. Referring to FIG. 9, the terminal may be provided with higher layer signaling regarding the starting common resource block (CRB) for each guard band and the size of the number of CRBs. For example, a CRB may be a resource block defined / set based on point A, which is the starting point of the transmission bandwidth on a carrier in the frequency domain. The terminal may check information regarding point A through base station signaling and, based on the information, may recognize the CRB position in the frequency domain. Here, each guard band is provided with a starting CRB. JPEG2025539708000015.jpg1326 is defined based on the parameters, and the size of the number of CRBs in each guard band is The UE may be provided with the above information through higher layer signaling based on the startCRB and nrofCRBs parameters, respectively. JPEG2025539708000017.jpg972, N RB-set,x is the number of RB sets, and x may be set to DL or UL for downlink and uplink. RB-set,xThe RB set may be configured as a resource block set (RBS) within one carrier through guard band configuration. For example, the guard band may be configured based on the IntraCellGuardBandsPerSCS parameter, thereby configuring the RBS within one carrier.

[0108] Here, each RBS frequency bandwidth may correspond to an LBT frequency bandwidth. That is, each RBS may be set to a bandwidth corresponding to an LBT procedure performed between a base station and a terminal. For example, in FIG. 9, RB set 1 (911) and RB set 2 (922) correspond to an LBT bandwidth, and if LBT is successful in that area, the band can be occupied to perform communication. That is, an RBS may correspond to an LBT bandwidth. For example, a transmitting node (e.g., a gNB or UE) can determine channel occupancy for an unlicensed band through an LBT channel access procedure performed on RBS resources corresponding to an LTE bandwidth. If the LBT procedure on one RBS is successful, the transmitting node can transmit on resources corresponding to that RBS.

[0109] Here, each RBS can be defined as a start CRB and an end CRB. The start CRB is JPEG2025539708000018.jpg1326 and the end CRB is JPEG2025539708000019.jpg1320. Here, the size of the guard band 913 may be nrofCRBs. As an example, the size of the guard band 913, nrofCRB, is determined by the subcarrier spacing μ and the carrier size It is not necessary to expect the size to be set to be smaller than the number of applicable intracell guard bands defined taking into consideration requirements regarding whether or not interference with wireless bandwidth is permitted by JPEG2025539708000020.jpg1322.

[0110] At this time, the start CRB and the end CRB for each RBS 911, 912 can be determined based on the RBS index s, and the RBS index s is JPEG2025539708000021.jpg970 That is, the RBS index s can be JPEG2025539708000022.jpg1323 may be a resource block having a size of JPEG2025539708000023.jpg1323 is the number of CRBs determined through the start CRB and end CRB based on Equation 3. Also, the start CRB and end CRB for each RBS may be as shown in Equation 4 and Equation 5.

[0111]

number

[0112]

number

[0113]

number

[0114] For example, if the UE is not provided with the IntraCellGuardBandsPerSCS parameter setting, the μ and carrier size of the carrier The CRB index for the nominal intra-cell guard band and RBS pattern based on JPEG2025539708000027.jpg1321 can be determined according to the requirements of the RF standard. Also, as an example, if the nominal intra-cell guard band and RBS pattern do not include the intra-cell guard band, the RBS of the corresponding carrier can be assumed to be 1.

[0115] For example, in FIG. 9, two LBT BWs (RBS0, RBS1) may be configured within one BWP 922 within one carrier bandwidth. In this case, one guard band 913 may be configured between the two RBSs 911, 913. The positions of the two RBSs 911, 913 may be determined as shown in FIG. 9 based on the above-mentioned higher layer parameters. Also, for example, when multiple BWPs 921, 923 are configured within one carrier bandwidth, the RBS associated with each BWP may be identified. Here, the RBSs corresponding to the first RBS (=s0, 912) and the last RBS (=s1, 911) of each BWP among the RBSs 911, 912 within the carrier may be indexed using the s0 and s1 indexes.

[0116] FIG. 10 is a diagram illustrating unlicensed bands applicable to the present disclosure. Referring to FIG. 10, the NR-U band, an unlicensed band for a wireless communication system (e.g., NR), may include two frequency ranges consisting of a low-frequency band below 7 GHz and a high-frequency band of 60 GHz. However, these bands are merely examples and are not limited thereto. As an example, in FIG. 10, the 2.4 GHz band is used for industrial scientific medical (ISM), the 3.5 GHz band is used for citizens broadband radio services (CBRS), and the 5 GHz to 6 GHz band is used for unlicensed national information infrastructure (UNII). The UNII (5.925 GHz to 7.125 GHz) band may include multiple bands (UNII-1, UNII-2, ..., UNII-8). The multiple bands within UNII (UNII-1, UNII-2, ..., UNII-8) may have different transmit power, indoor / outdoor operation, maximum effective isotropic radiated power (EIRP), and dynamic frequency selection (DFS) requirements for each band, but are not limited to any particular form.

[0117] The 5 GHz to 6 GHz band can be divided into non-overlapping 20 MHz channel bandwidths. Here, channels with wider bandwidths, such as 40 MHz, 80 MHz, and 160 MHz, can be configured based on the boundaries. For example, a portion of the 6 GHz band can coexist with systems using backhaul communications (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. Furthermore, the UNII-5 band (5.925 to 6.425 GHz) can be used indoors and outside protected areas. Here, the indoor EIRP may be determined as 30 dBm (AP) and 24 dBM (UE), and the outdoor EIRP may be determined as 36 dBm (AP) and 30 dBM (UE), but this is not limited to a specific form.

[0118] The channel described below may be part of one carrier or multiple consecutive resource blocks (RBs) within a carrier. As an example, a channel access procedure may be a procedure for checking a channel based on sensing to perform transmission. When performing the channel access procedure, a base station or a terminal performs energy detection on a slot-by-slot basis, and if the energy is below a preset threshold, the base station or a terminal may determine that the channel is idle. A method for operating in an unlicensed band based on the above-mentioned operation will be described below.

[0119] FIG. 11 is a diagram illustrating a sidelink resource pool to which the present disclosure can be applied. Referring to FIG. 11, a terminal may be configured with multiple transmit (Tx) resource pools (RPs) and receive (Rx) RPs. Resource pools may be differentiated by an identification (ID) and added or removed from the terminal. Furthermore, as an example, each resource pool configuration may be different. Specifically, the PSCCH, PSSCH, and PSFCH configurations of a resource pool may be different for each resource pool. Furthermore, a resource pool may be configured with a starting position of a subchannel indicating the location of resources in the frequency aspect within a SL BWP, the number of RBs, and a subchannel size. Furthermore, a resource pool may be configured with the location of time resources in the time aspect in a bitmap format. Here, time resources are mapped excluding slots used for SSB and uplink (UL), and may be repeatedly applied for each bit configured within a system frame number (SFN).

[0120] As a specific example, referring to FIG. 11, the UE may determine the resource location in a specific resource pool within the SL BWP. The subchannel size may refer to a physical resource block (PRB), which is the smallest unit for selecting resources. Also, 'sl-StartRBsubchannel' may indicate the start RB of a subchannel within the SL BWP, 'sl-RB-Number' may indicate the number of RBs available within the SL BWP, and 'sl-SubchannelSize' may indicate the size of one subchannel. The UE may determine how many subchannels to use within the SL BWP based on the above parameters. Furthermore, as an example, time resources may be indicated in slot units via 'sl-TimeResource'. As a specific example, if the UE receives '0011111100' as a 10-bit indicator, the UE may use resources in slots indicated by 1, excluding slots including reserved slot SSBs. Furthermore, the UE may not use slots that are not included in the above subchannel RBs within the SL BWP or that are indicated by 0 in 'sl-TimeResource'. Furthermore, as an example, up to four SL BWPs may be configured, and one of the configured BWPs may be activated and used. Also, up to eight Tx resource pools and up to 16 Rx resource pools may be configured within the SL BWP, and are not limited to a specific embodiment.

[0121] Furthermore, the UE can receive and decode data and transmit hybrid automatic repeat and request (HARQ) feedback in response based on whether the reception was successful. For example, the UE can determine whether decoding failed by combining the initial transmission and retransmission. In current wireless communication systems (e.g., NR), both the downlink (DL) and uplink (UL) use an asynchronous HARQ incremental redundancy (IR) scheme. The base station provides the UE with a HARQ feedback timing configuration through a radio resource control (RRC) message and can dynamically instruct the HARQ feedback timing through DCI.

[0122] As a specific example, a base station can indicate transmission timing to a terminal through DCI. For example, K0 in the DCI can indicate the interval between DCI transmitted on a PDCCH (Physical Downlink Control Channel) and DL data transmitted on a PDSCH (Physical Downlink Shared Channel). In addition, K1 in the DCI can indicate the interval between PDSCH DL data reception and UL HARQ feedback timing transmitted on a PUCCH (Physical Uplink Control Channel). Furthermore, K2 in the DCI can indicate the interval between PDCCH UL grant reception and UL data transmitted on a PUSCH (Physical Uplink Shared Channel).

[0123] For example, HARQ feedback operation may also be considered in sidelink communication. More specifically, the medium access control (MAC) entity of the UE may include up to one sidelink HARQ entity for sidelink shared channel (SL-SCH) transmission. The sidelink HARQ entity may support up to 16 sidelink processes. A sidelink process may be configured to enable multiple MAC protocol data unit (PDU) transmissions. For example, in resource allocation mode 2, in which the UE directly determines sidelink resources, the UE may configure up to four sidelink processes for multiple MAC PDU transmissions. Furthermore, sidelink grants transmitted to the MAC entity and information associated with these sidelink grants may be associated with and configured as sidelink processes. Each sidelink process may be used to transmit one transport block (TB).

[0124] As another example, a sidelink discontinuous reception (DRX) operation can be considered. Here, a sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) can be configured for a sidelink process in a sidelink HARQ entity of the UE, and an operation can be performed based on the configured timer. The sidelink DRX HARQ RTT timer can be configured differently depending on at least one of whether HARQ feedback is enabled (HARQ feedback disable / enable), whether a physical sidelink feedback channel (PSFCH) is present, whether retransmission resources are available within sidelink control information (SCI), and / or the HARQ feedback scheme (e.g., ACK / NACK, NACK Only).

[0125] 12 illustrates a sidelink DRX HARQ RTT timer according to the present disclosure. For example, in a resource pool in which a PSFCH is configured, the HARQ feedback enable indicator in the SCI may be set to a first value, thereby enabling HARQ feedback and not indicating retransmission resources. However, this is merely a configuration for convenience of explanation and is not limited to this embodiment.

[0126] In FIG. 12, slot 1 1210 may be a slot in which a PSFCH is configured, and slot 2 1220 may be a slot in which a PSFCH is not configured. If the UE receives the PSCCH and PSSCH in slot 1 1210, the UE may transmit HARQ feedback in the sidelink slot (slot 3, 1230) in which a PSFCH is configured after two slots based on the configured sl-MinTimeGapPSFCH parameter. Since the UE can expect to receive a retransmission grant or a new grant based on the HARQ feedback in the first slot after PSFCH transmission, the sidelink DRX timer configured according to higher layer parameters may operate based on the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer). For example, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) may refer to the minimum time before anticipating an allocation for HARQ retransmission, and the UE may be in a sleep state during this time. In addition, a sidelink DRX HARQ RTT timer (SL drx-HARQ-RTT-Timer) can be configured for each HARQ process. For example, although the sidelink DRX HARQ RTT timer will be referred to as a sidelink DRX HARQ RTT timer hereinafter for convenience of explanation, a sidelink DRX HARQ RTT timer performing the same function may be referred to by other names and is not limited to a specific form. As another example, even if the UE does not transmit sidelink HARQ feedback in 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 slot after the PSFCH resource is exhausted in order to receive a retransmission grant.

[0127] For example, if HARQ feedback is enabled in a resource pool in which a PSFCH is configured and a retransmission resource is configured in the SCI, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) may be derived from the next retransmission resource in the SCI. As another example, if HARQ feedback is disabled and there are no retransmission resources in the SCI, the UE may operate the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) after the PSFCH. On the other hand, if HARQ feedback is disabled and there are retransmission resources in the SCI, the UE may operate the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) from the received PSSCH to the next retransmission resource in the SCI, thereby reducing the power consumption of the UE.

[0128] FIG. 13 illustrates a method for operating a sidelink timer in a resource pool in which a PSFCH is not configured, according to the present disclosure. Referring to FIG. 13, a resource pool in which a PSFCH is not configured can be considered. Since the UE does not perform HARQ feedback operations in this resource pool, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) can be operated after the PSCCH 1310 indicated by the SCI. For example, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) may be started on a slot-by-slot basis, and the timer length may also be set on a slot-by-slot basis. Furthermore, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) may operate differently depending on whether or not a retransmission resource exists in the SCI. As a specific example, if there is no retransmission resource in the SCI, the operation may differ depending on whether or not a retransmission resource exists in the SCI. If there are no retransmission resources in the SCI, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) can operate regardless of whether HARQ feedback is enabled. On the other hand, if 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 next retransmission resource. As another example, two sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) values ​​can be set depending on whether there is a PSFCH in the resource pool, and this is not limited to a specific embodiment.

[0129] FIG. 14 illustrates a sidelink HARQ feedback operation applied to the present disclosure. Referring to FIG. 14, when a receiving terminal receives a PSSCH 1410 in slot n, the receiving terminal may determine a PSFCH occasion for performing HARQ feedback according to a configured higher layer parameter (e.g., sl-MinTimeGapPSFCH). As a specific example, in FIG. 14, sl-MinTimeGapPSFCH may be configured as three slots as the higher layer parameter. The terminal may perform HARQ feedback in the first PSFCH occasion 1430 occurring after slot n+3, which is three slots from slot n. As a specific example, consider a case where the PSFCH period is set to 4 in a resource pool. However, this is merely an example for convenience of explanation and is not limited thereto. A PSFCH occasion may be configured every four sidelink slots based on a PSFCH period of 4. In FIG. 14, if the terminal receives PSSCH 1410 in slot n, the terminal can perform HARQ feedback in slot n+5, in which the first PSFCH occasion 1430 occurring after sl-MinTimeGapPSFCH occurs.

[0130] FIG. 15 is a diagram illustrating PSSCH-PSFCH mapping for HARQ feedback transmission applied to the present disclosure. Referring to FIG. 15, the sidelink HARQ feedback resource is not explicitly indicated but may be implicitly configured. The terminal may derive the association between the PSSCH and the PSFCH based on preconfigured higher layer parameters and perform HARQ feedback through the PSFCH resource associated with the received PSSCH. As a specific example, in FIG. 15, the number of subchannels in the resource pool (N subch, sl-NumSubchannel) and the PSFCH occasion may be configured every four slots by sl-PSFCH-period. Here, the PSFCH slots associated with one PSFCH occasion are JPEG2025539708000028.jpg923 can be four, but this is merely an example for the convenience of explanation and is not limited to this embodiment.

[0131] The UE can map PSFCH resources to PSSCH resources through configured parameters. In addition, a PRB (physical resource block) for HARQ feedback within a PSFCH occasion can be used. JPEG2025539708000029.jpg1326 may be indicated by a bit string of 0 or 1. As an example, in FIG. 15, the PRB for HARQ feedback in the PSFCH occasion The total number of JPEG2025539708000030.jpg1326 may be 80. Here, the 80 PRBs for HARQ feedback may refer to PRBs indicated by 1 among bit strings of 10 to 270. The 80 PRBs for HARQ feedback in one PSFCH occasion may be allocated to slots and subchannels associated with the PSFCH based on Equation 6 below.

[0132]

number

[0133] where: JPEG2025539708000032.jpg1350 means the slot number associated with the PSFCH, and j (0 ≤ j <N subch ) can mean the number of the subchannel. JPEG2025539708000033.jpg1335 is PRB for HARQ feedback JPEG2025539708000034.jpg1326 divided by the number of subchannels and the number of slots associated with the PSFCH, i.e., the PRB for HARQ feedback within a PSFCH occasion. JPEG2025539708000035.jpg1326 is for each subchannel of the slot associated with the PSFCH. JPEG2025539708000036.jpg1335 can be allocated at a time. For example, in FIG. 15, if there are four subchannels and the number of slots associated with the PSFCH is four, there can be 16 subchannels. Here, the PRBs for HARQ feedback are If the number of JPEG2025539708000037.jpg1326 is 80, then there will be 5 PRBs for each subchannel. JPEG2025539708000038.jpg1344 can be used for HARQ feedback.

[0134] The terminal selects a resource for transmitting HARQ feedback within the PSFCH PRB associated with the subchannel. JPEG2025539708000039.jpg1335, each PRB is the number of CS (cyclic shift) pairs If there are two JPEG2025539708000040.jpg1391 and sl-PSFCH-CandidateResourceType is set to "startSubCH" JPEG2025539708000041.jpg931, the number of PSFCH candidate resources associated with a specific subchannel can be derived as shown in Equation 7 below.

[0135]

number

[0136] where: JPEG2025539708000043.jpg1323 may be 20, and the 20 candidate resources may be numbered according to the CS order after the PRB ascending order. The UE may select a PSFCH resource according to the index derived from Equation 8 below. As another example, when sl-PSFCH-CandidateResourceType is set to allocSubCH, JPEG2025539708000044.jpg940, the number of PSFCH candidate resources can be configured differently.

[0137]

number

[0138] where P ID is the physical layer source ID indicated through SCI format 2-A / 2-B / 2-C, and M ID may refer to an upper layer UE identifier used for groupcast HARQ ACK-NACK feedback. For example, in the case of unicast or groupcast HARQ NACK-only, M ID can be 0.

[0139] Further, as an example, a terminal may perform a listen before talk (LBT) procedure for channel occupancy in an unlicensed band. The LBT procedure may be a procedure for determining whether a channel is occupied through a channel clear assessment (CCA) check before using the channel. The CCA check may be an operation for performing sensing during a CCA period. The CCA check may use energy detection (ED) to detect the presence or absence of other signals in the channel. Specifically, if the energy (e.g., received signal strength indicator (RSSI)) detected during the CCA period is less than an energy threshold (ED threshold), the terminal may determine that the channel is unoccupied and occupy the channel during the channel occupancy time (COT). Conversely, if the energy detected during the CCA period is greater than the energy threshold, the terminal may determine that the channel is occupied, and the CCA period may be extended until the channel can be occupied. For example, LBT may be a mandatory procedure for operation in the 5 GHz and 60 GHz unlicensed bands in Europe and Japan, but may not be defined as a mandatory procedure in the United States and China. The CCA slot duration may be, but is not limited to, 9 μs in the 5 GHz band and 5 μs in the 60 GHz band. More specifically, in the 60 GHz band, the initial CCA may be set to a multiple of 5 μs, and the extended CCA may be set to 8 + m × 5 μs, where m is a backoff counter. In addition, in the case of a 20 MHz channel bandwidth, the ED threshold may be, but is not limited to, −72 dBm in the 5 GHz band and −47 dBm in the 60 GHz band.

[0140] As an example, the LBT category may be, but is not limited to, Category 1 to Category 4 shown in Table 10 below.

[0141] [Table 10]

[0142] Here, the terminal can use different categories depending on the transmission purpose. For example, the terminal and base station can use Cat 4 LBT for data transmission in license-assisted access (LAA). Conversely, when the base station transmits a discovery reference signal, Cat 2 LBT can be used. As another example, in NR-U, in COT sharing operation when the base station occupies the channel, if the interval between DL and UL transmission is less than 16 μs, the terminal can perform Cat 1 LBT without CCA check. Conversely, if the interval between DL and UL transmission is greater than 16 μs but less than 25 μs, the terminal can perform Cat 2 LBT using short sensing. Furthermore, if the interval between DL and UL transmission is greater than 25 μs, the terminal can perform Cat 4 LBT, which is used for general data transmission. Here, LAA supports only one DL / UL switching, but NR-U can support multiple DL / UL switching.

[0143] For example, in certain regions (e.g., Europe and Japan), continuous transmission in unlicensed bands may be restricted. That is, the maximum channel occupancy time (MCOT) may be limited to the time during which a terminal can continuously use a channel. For example, the MCOT may be limited to 2 ms, 4 ms, or 6 ms depending on the priority class in the 5 GHz band. Furthermore, the MCOT may be limited to 9 ms in the 60 GHz band, but is not limited thereto. Furthermore, for example, a terminal and a base station may share a COT in the 5 GHz and 60 GHz bands. That is, a combination of downlink (DL) and uplink (UL) transmissions may be possible within the COT. Specifically, if a base station occupies a channel through a listen before talk (LBT) procedure and the terminal performs DL transmission, the terminal can immediately perform UL transmission without channel clear assessment (CCA) confirmation.

[0144] After successful LBT, the UE can occupy and use the channel for only MCOT. Here, current wireless communication systems (e.g., NR) can perform unlicensed band transmission and reception operations more efficiently than existing wireless communication systems (e.g., LTE) due to flexible slot structures such as minislots. Therefore, the COT is shared between the base station and the UE, allowing the UE to improve spectral efficiency or perform a quick response operation.

[0145] FIG. 16 illustrates a COT structure applicable to the present disclosure. As an example, a wireless communication system may support single DL / UL switching or multiple DL / UL switching. As a specific example, referring to FIG. 16(a), single DL / UL switching may be configured to be performed only once within a COT. Single DL / UL switching can reduce overhead by reducing the guard band, and when the interval between DL and UL is greater than 16 μs, multiple LBT procedures may not be performed. However, since single DL / UL switching configures UL operation only once after a certain period of time following DL, delays may occur in HARQ feedback and UL scheduling. For example, UL scheduling delays may occur when Cat 4 LBT is attempted and fails during UL operation. Considering the above, a single DL / UL switching COT configuration may be suitable for, but not limited to, eMBB (enhanced Mobile Broadband) traffic, which has high throughput and flexible delay requirements.

[0146] Further, referring to FIG. 16(b), as an example, a multiple DL / UL switching COT configuration can provide multiple opportunities to perform UL. Therefore, a multiple DL / UL switching COT configuration can facilitate HARQ feedback configuration. When sensing by UL transmission LBT must be performed (i.e., when the interval between UL and DL is greater than 16 μs), a multiple DL / UL switching COT configuration can ensure channel usage. Because the base station performs a CCA check for DL ​​transmission, LBT may be successful if it is performed relatively close to the time of the DL transmission. However, because a multiple DL / UL switching COT configuration includes multiple guard bands, multiple LBT procedures may need to be performed. Considering the above, a multiple DL / UL switching COT configuration may be suitable for massive machine-type communications (mMTC) with delay-sensitive traffic and low-load traffic, such as ultra-reliable low latency communications (URL) and enhanced V2X (eV2X), but is not limited to this.

[0147] Further, by way of example, power (EIRP, PSD) can be limited in all regions and bands to limit inter-RAT and intra-RAT interference in unlicensed band operation, as described above.

[0148] Furthermore, by way of example, the occupied channel bandwidth (OCB) can be defined as the bandwidth in a particular region that contains 99% of the signal power. This may mean that a majority of the channel bandwidth must be used when connecting to a channel in an unlicensed band. By way of example, but not limitation, at 5 GHz, the OCB may be 70-100% of the nominal channel bandwidth (NCB), and at 60 GHz, the OCB may be 80-100% of the NCB.

[0149] Furthermore, as unlicensed spectrum scenarios, licensed assisted access (LAA), existing unlicensed spectrum communications (LTE-unlicensed), and multi-fire technologies have been defined for operation in the 5 GHz band. However, current unlicensed spectrum communications (NR-unlicensed) can be designed taking into account multiple bands, such as, but not limited to, 2.4 GHz, 3.5 GHz, 5 GHz, 6 GHz, 37 GHz, and 60 GHz. Furthermore, as an example, unlicensed spectrum can be divided into sub-7 GHz bands and mmWave bands. Sub-7 GHz includes the 2.4, 3.5, 5, and 6 GHz bands, and mmWave bands include, but are not limited to, 37 GHz and 60 GHz.

[0150] FIG. 17 illustrates a method for detecting consecutive LBT failures applicable to the present disclosure. In a wireless communication system (e.g., NR), a terminal may perform LBT in an unlicensed band. Referring to FIG. 17, the terminal may detect an LBT failure. The physical layer of the terminal performs an LBT procedure before performing transmission, and if the LBT is successful, the terminal may occupy the channel and perform transmission. Conversely, if the LBT fails during the LBT procedure, the terminal may not be able to occupy the channel and may not be able to perform transmission. Here, if the terminal does not occupy the channel due to an LBT failure, the physical layer of the terminal may deliver an LBT failure indication (1710) to the MAC layer of the terminal. The MAC layer of the terminal may be configured with a consistent LBT failure recovery procedure through higher layer signaling (e.g., RRC). As an example, the terminal may count and detect consecutive LBT failures per uplink bandwidth part (UL BWP).

[0151] In addition, the UE can receive the configuration of the LBT failure instance maximum counter (lbt-FailureInstanceMaxCounter) and the LBT failure detection timer (lbt-FailureDetectionTimer) through higher layer signaling. The UE can also receive the configuration of the LBT counter (LBT_COUNTER), which counts LBT failures for each serving cell as a UE variable through higher layer signaling.

[0152] As a specific example, referring to FIG. 17(a), when the MAC layer of the terminal receives an LBT failure indication 1710 from the physical layer of the terminal, the MAC layer of the terminal may increment the LBT counter (LBT_COUNTER) and (re)start the LBT failure detection timer (lbt-FailureDetectionTimer). Here, when the LBT failure detection timer (lbt-FailureDetectionTimer) expires, the terminal may initialize the LBT counter (LBT_COUNTER) to 0. Further, as an example, referring to FIG. 17(b), when the LBT counter (LBT_COUNTER) becomes equal to or greater than the LBT failure instance maximum counter (lbt-FailureInstanceMaxCounter), the terminal may generate consecutive LBT failures. For example, if the serving cell in which consecutive LBT failures occur is a special cell (SpCell), and consecutive LBT failures occur in all UL BWPs configured with physical random access channel (PRACH) occasions on the carrier of the serving cell, the UE may indicate consecutive LBT failures to a higher layer. For example, if consecutive LBT failures do not occur for a UL BWP configured with at least one PRACH occasion, the UE may terminate ongoing random access to the serving cell, configure a PRACH occasion in an active UL BWP, switch to a UL BWP in which consecutive LBT failures do not occur, and perform random access.

[0153] Further, as an example, consecutive LBT failures may occur for an SpCell and not be canceled. If uplink-shared channel (UL-SCH) resources for new transmission exist and an LBT failure MAC CE and subheader can be included according to a logical channel prioritization (LCP) result, the MAC layer of the UE may instruct to generate an LBT failure MAC CE through a multiplexing and assembly procedure. As an example, the SpCell may refer to a PCell. Also, in the case of dual connectivity (DC), the SpCell may refer to a PCell of a master cell group (MCG) and a PSCell of a secondary cell group (SCG). Note that, as an example, the serving cell may refer to a PCell, a PSCell, or an SCell.

[0154] Further, as an example, a case may be considered in which consecutive LBT failures occur for at least one SCel and are not canceled. Here, if an UL-SCH resource for new transmission exists and can include an LBT failure MAC control element (MAC CE) and a subheader, the UE MAC layer may instruct generation of an LBT failure MAC CE through a multiplexing and assembly procedure. Otherwise, the UE MAC layer may perform a scheduling request (SR) procedure for LBT failure MAC CE transmission. Further, as an example, if consecutive LBT failures occur for an SpCell and random access is successfully performed after switching to another UL BWP, the UE MAC layer may cancel all the consecutive LBT failures that occurred. Furthermore, if the UE MAC layer does not receive an LBT failure from the physical layer associated with a MAC protocol data unit (MAC PDU) transmission including an LBT failure MAC CE, the UE MAC layer may cancel all the consecutive LBT failures that occurred for SCels included within the LBT failure MAC CE. As an example, FIG. 18 illustrates an LBT failure MAC CE applied to the present disclosure. Referring to Figure 18, C i In the above, i may represent the index of the serving cell (ServCellIndex), where the field of the serving cell in which consecutive LBT failures have occurred may be set to 1, and the other fields may be set to 0.

[0155] For example, sidelink communication can support enhanced V2X applications. Furthermore, sidelink communication can support proximity-based public safety and commercial services, including, but not limited to, partial sensing, discontinuous reception (DRX), and inter-UE coordination operations to improve power consumption and data reliability in battery-limited devices.

[0156] In addition, sidelink communication may be operated with an increased data rate. For example, the increased data rate may be used to share large amounts of sensor information, such as vehicle-to-vehicle video, for highly autonomous driving. The increased data rate may be achieved through methods such as sidelink carrier aggregation and sidelink unlicensed band operation, but is not limited to these embodiments. Support for new carrier frequencies for sidelink operation may also be considered. The increased data rate may be achieved through FR2 sidelink operation with new frequencies and wider bandwidth. For example, currently, the use of ITS (intelligent transport system) frequency bands is limited to applications related to ITS safety. However, support for unlicensed band operation in sidelink communication may enable commercial services due to improved performance. For example, a V2X scenario in which LTE V2X and NR V2X terminals share the same frequency channel may also be considered. A method for efficiently allocating resources without adversely affecting other types of terminals may also be needed, but is not limited to this.

[0157] Considering the above, the following describes a consistent LBT failure operation during sidelink-unlicensed (SL-U) operation. As an example, a UE can perform sidelink transmission if the LBT procedure is successful in SL-U. Conversely, if the UE performs the LBT procedure in SL-U and does not occupy the channel due to an LBT failure, it may not be able to perform sidelink transmission. Considering the above situation, the following describes a consistent LBT failure declaration and recovery operation.

[0158] For example, the UE may perform a consistent LBT failure detection and recovery procedure taking into account the unlicensed band. The UE performs the LBT procedure in the unlicensed band, and if the LBT is successful, it can occupy the channel and perform transmission. Conversely, if the LBT fails in the unlicensed band, the UE may not be able to occupy the channel and may not be able to perform transmission. Furthermore, if the LBT fails persistently, the UE may perform BWP switching and LBT failure MAC CE reporting procedures. This allows for the execution of an LBT failure recovery operation. In the unlicensed band of the wireless communication system, the LBT failure detection unit may be the UL BWP. Here, for example, a sidelink unlicensed band (SL-U) may have a resource pool, unlike the unlicensed band of the wireless communication system. Furthermore, the SL-U may have a different resource structure from the wireless communication system. In consideration of the above, the LBT detection unit may be set to be different from that of the unlicensed band of the wireless communication system in the SL-U, and operations after the consecutive LBT failures may be performed based on the LBT detection unit.

[0159] As a specific example, the LBT failure detection unit may be at least one of an RB set (LBT bandwidth), a resource pool, an SL carrier, and a BWP. For example, in SL-U, a UE may perform LBT in units of RB sets to perform channel connection and occupation. Here, an SL carrier may include multiple RB sets. For example, since an SL BWP is configured as one, it may be inappropriate as a unit for detecting consecutive LBT failures, but this is not limiting. In consideration of the above, the unit for detecting consecutive LBT failures may be configured in units of a resource pool or an RB set, and the following description will be given in relation to this.

[0160] The physical layer of the terminal can occupy a channel only at a specific time based on the success of the LBT in the unlicensed band and can continuously attempt channel access to the specific occupied channel (e.g., RB set). Here, continuous LBT failure may be a situation in which LBT failures occur continuously. That is, a channel (e.g., RB set or resource pool) in which continuous LBT failures occur may indicate a situation in which the channel is heavily loaded and difficult to occupy, and it is necessary to attempt channel access to another channel.

[0161] Here, as an example, in a mode in which the UE directly performs scheduling, a mode 2 UE can detect consecutive LBT failures based on the configured consecutive LBT failure detection unit and perform an operation based thereon. Furthermore, in a mode in which the base station schedules sidelink communication resources, the UE can report consecutive LBT failures to the base station for consecutive LBT failure recovery, which will be described later.

[0162] As an example, detection of consecutive LBT failures may be performed on an RB set basis or on a resource pool basis, as shown in Table 11 below. As a specific example, in Table 11, when consecutive LBT failures are detected on an RB set basis, if a resource pool includes multiple RB sets and consecutive LBT failures are not detected in at least one RB set, resource reselection may be performed. On the other hand, when consecutive LBT failures are detected on an RB set basis, if a resource pool includes one RB set and consecutive LBT failures are detected in the RB set, resource pool reselection may be performed. As another example, when consecutive LBT failures are detected on a resource pool basis, if an SL BWP includes a resource pool in which consecutive LBT failures are not triggered and consecutive LBT failures are detected in the set, resource pool reselection may be performed.

[0163] [Table 11]

[0164] For example, one SL BWP may be configured in a terminal, and multiple resource pools may be configured in the configured SL BWP. Furthermore, a resource pool may include one or more RB sets, and the RB set may be a unit for performing LBT.

[0165] Here, when consecutive LBT failures are detected for each RB set as shown in Table 11, the UE MAC layer may select a resource pool and select multiple resources divided into time resources and frequency resources based on the single / multiple MAC PDUs and the number of HARQ retransmissions. Furthermore, the UE MAC layer may continuously perform a Tx resource (re)selection check operation until the resources of the selected resource pool are released by the upper layer or the generation of the selected SL grant for multiple MAC PDUs is canceled. The Tx resource (re)selection check is performed by checking the PSCCH (physical sidelink control channel) and 2 nd The procedure may determine whether to maintain the use and reservation of selected resources in a resource pool based on at least one of the following: when the PSSCH of the sidelink control information (SCI) indicates that the destination terminal is not in the SL activation time; when the sidelink resource reselection counter (SL_RESOURCE_RESELECTION_COUNTER) becomes 0; when resources in the resource pool are (re)configured by higher layer signaling; and when resources indicated by the selected SL grant are not used for a certain number of consecutive times or more. As an example, all selected SL grants associated with the sidelink process may be released if the above-mentioned conditions are met, and a procedure may be performed in which transmission resource (re)selection is performed to allocate newly selected SL grants to the selected resource pool through new resource selection and reservation.

[0166] Further, as an example, when consecutive LBT failures are detected on an RB set basis, resource reselection may be performed if the selected resource pool includes an RB set in which consecutive LBT failures do not occur. As a specific example, the MAC layer of the terminal may select resources from the resource pool based on a single MAC PDU or multiple MAC PDUs, generate a selected SL grant, and associate it with the sidelink process. In an unlicensed band, the terminal may perform an LBT operation before transmitting, and if LBT failures occur persistently, consecutive LBT failures may occur in the RB set in which the LBT was performed. Thus, if the terminal can no longer maintain the selected resources in the resource pool, and if an RB set in the resource pool in which consecutive LBT failures do not occur exists, the terminal may perform resource reselection in the RB set.

[0167] That is, the UE can select resources for a single MAC PDU / multiple MAC PDUs, generate the selected SL grant, and associate it with the sidelink grant.

[0168] FIG. 19 illustrates an RB set-based continuous LBT failure detection method that may be applied to the present disclosure. Referring to FIG. 19, an SL BWP includes two RB sets 1910 and 1920, and a resource pool 1930 may include both RB sets 1910 and 1920. However, this is merely an example for convenience of explanation and is not limiting. The MAC layer of the UE may select resource pool 0 (resource pool 0, 1930). The MAC layer of the UE may select multiple resources partitioned in 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 a transmission resource (re)selection check operation until the resources of the selected resource pool are released by higher layer signaling or until generation of the selected SL grants for multiple MAC PDUs is canceled. The physical layer of the UE may perform an LBT operation before transmitting the selected SL grant on the selected resources. Here, the LBT operation may be performed on an RB set basis. When a UE performs an LBT operation and an LBT failure occurs continuously in a specific RB set, consecutive LBT failures may occur. As an example, consecutive LBT failures may occur in RB set 01910 in FIG. 19, but this is merely a configuration for convenience of explanation and is not limiting.

[0169] For example, if consecutive LBT failures occur in RB set 0 (1910), the UE MAC layer may perform different operations depending on whether the selected resource pool includes multiple RB sets and whether an RB set in which consecutive LBT failures do not occur exists. As a specific example, if the resource pool 1930 includes multiple RB sets 1910 and 1920 and an RB set in which consecutive LBT failures do not occur exists, the UE MAC layer may release the selected SL grant associated with the sidelink process through a transmission resource (re)selection check procedure and perform a transmission resource (re)selection check operation. The UE MAC layer may select multiple resources divided into time and frequency through a transmission resource (re)selection procedure based on a single / multiple MAC PDUs and the number of HARQ retransmissions. Here, an operation of selecting resources within an RB set in which consecutive LBT failures do not occur may be required. For example, the UE MAC layer may perform resource selection considering whether consecutive LBT failures occur in the candidate resource set transmitted by the UE physical layer. That is, the MAC layer of the terminal can independently perform resource selection taking into account whether or not consecutive LBT failures have occurred, and since it does not affect the existing operation in the physical layer, it can be the same.

[0170] As another example, when the UE MAC layer selects resources from a candidate resource set transmitted by the UE physical layer, the UE MAC layer may transmit information about the RB set in which consecutive LBT failures have occurred to the UE physical layer. The UE physical layer may configure a candidate resource set by excluding resources in the RB set in which consecutive LBT failures have occurred from the candidate resource set, and transmit the candidate resource set to the UE MAC layer. In the above case, the UE MAC layer may perform resource selection from the candidate resource set as before.

[0171] 20 is a diagram illustrating a method for a terminal's MAC layer to select resources in a resource pool based on consecutive LBT failures, which can be applied to the present disclosure. As an example, an SL BWP includes two RB sets (RB set 0 and RB set 1), and a resource pool can include two RB sets. That is, the terminal's MAC layer can select a specific resource pool that includes both RB set 0 and RB set 1.

[0172] As an example, if consecutive LBT failures are detected in an unlicensed band on an RB set basis, the MAC layer of the terminal may perform a transmission resource (re)selection check. The MAC layer of the terminal may release the selected SL grant for the selected and reserved resource, and select multiple resources divided into time and frequency based on the number of single / multiple MAC PDUs and HARQ retransmissions. More specifically, referring to FIG. 20(a), if consecutive LBT failures occur in RB set 0 (2010) based on the sensing-based resource selection method, the MAC layer of the terminal may generate a transmission resource (re)selection and select a new resource. Here, the MAC layer of the terminal may select a new resource based on the candidate resource set (S) reported by the physical layer of the terminal. A , SetA), a resource in the RB set (RB Set 1, 2020) in which continuous LBT failures do not occur can be selected.

[0173] As another example, referring to FIG. 20(b), when consecutive LBT failures occur in RB set 0 (2010) based on the random-based resource selection method, the MAC layer of the terminal may generate a transmission resource (re)selection and select a new resource. Here, the MAC layer of the terminal may select a new resource from the candidate resource set (S A , SetA), a resource in the RB set (RB Set 1, 2020) in which continuous LBT failures do not occur can be selected.

[0174] Further, as an example, if there is no RB set in the resource pool in which consecutive LBT failures do not occur, the MAC layer of the terminal may perform a procedure to select another resource pool including an RB set in which consecutive LBT failures do not occur in the SL BWP.

[0175] FIG. 21 is a flowchart illustrating a method for detecting consecutive LBT failures on an RB set basis that can be applied to the present disclosure. Referring to FIG. 21, a MAC layer of a terminal operating in Mode 2, in which the terminal directly selects sidelink communication resources, can determine single / multiple MAC PDU generation and perform operations based on the determination. The MAC layer of the terminal can select a resource pool and select one resource for an initial transmission or a retransmission opportunity (step 1, S2110). For example, a resource pool may include one or more RB sets. The MAC layer of the terminal then checks whether consecutive LBT failures have occurred in a specific RB set within the resource pool (step 2, S2120). If consecutive LBT failures do not occur, the MAC layer of the terminal can continuously check whether consecutive LBT failures have occurred in a specific RB set. On the other hand, if consecutive LBT failures have occurred in a specific RB set, the MAC layer of the terminal can check whether a resource set exists in which consecutive LBT failures do not occur (step 3, S2130). For example, if there is no RB set in which consecutive LBT failures do not occur in a specific RB set, the UE MAC layer may perform the resource pool and resource selection procedure again. On the other hand, if there is one or more RB sets in which consecutive LBT failures do not occur in a specific RB set, the UE MAC layer may perform a transmission resource (re)selection operation (step 4, S2140). Since there is an RB set in which consecutive LBT failures do not occur in the resource pool, the UE MAC layer may release one or more resources selected in the resource pool and resource selection procedure in step 1 and select one or more new resources from the RB set. Then, the UE MAC layer may select resources in one or more RB sets in which consecutive LBT failures do not occur as the one or more newly selected resources (step 5, S2150).

[0176] 22 is a diagram illustrating a method for determining a candidate resource set based on consecutive LBT failures that can be applied to the present disclosure. Referring to FIG. 22, a physical layer of a terminal may determine a candidate resource set in consideration of consecutive LBT failures. As an example, the physical layer of the terminal may receive a request from a higher layer and determine a possible candidate resource set in a designated resource pool based on the received request. The physical layer of the terminal may then report the determined candidate resource set to the higher layer.

[0177] Here, if consecutive LBT failures are detected in units of an RB set, the RB set may not be used until the consecutive LBT failures are resolved. Therefore, the physical layer of the UE needs to report information about new candidate resource sets to a higher layer. As a specific example, after detecting consecutive LBT failures in RB set 0 (2210), the MAC layer of the UE may request a resource set that can be determined for PSCCH / PSSCH transmission from the physical layer of the UE. As an example, the MAC layer of the UE may transmit information about one or more RB sets in which consecutive LBT failures have occurred to the physical layer of the UE. Thereafter, the physical layer of the UE may perform a procedure to eliminate resources reserved through other SCIs within the selection window, and then eliminate the resources in which consecutive LBT failures have occurred.

[0178] 22, the UE's physical layer may determine a candidate resource set 2230 within n+T1 to n+T2. The candidate resource set 2230 may include resources 2240 excluded through the SCI received within n+T1 to n+T2 and resources 2250 in the RB set where consecutive LBT failures have occurred. Here, point n may be the point at which the UE's MAC layer provides parameters for requesting a candidate resource set, and the UE's physical layer may ultimately determine the candidate resource set 2230 and report it to the UE's MAC layer. When selecting a selected SL grant resource, the UE's MAC layer may select resources within the candidate resource set 2230 reported by the physical layer without considering consecutive LBT failures.

[0179] As another example, a case in which continuous LBT failure detection is performed on a resource pool basis may be considered. 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 a transmission resource (re)selection check operation until the resources of the selected resource pool are released by higher layer signaling or the generation of the selected SL grant for multiple MAC PDUs is canceled. The transmission resource (re)selection check may be a procedure for determining whether to maintain the use and reservation of the resources selected in the resource pool based on at least one of the following: when the PSCCH of the selected SL grant and the PSSCH of the 2nd SCI are not in the SL activation time in the destination UE; when the sidelink resource reselection counter (SL_RESOURCE_RESELECTION_COUNTER) becomes 0; when the resources of the resource pool are (re)configured by higher layer signaling; and when the resources indicated by the selected SL grant are not used consecutively for a certain number of times or more. For example, all selected SL grants associated with the sidelink process may be released if the above-mentioned conditions are met, and all SL grant resources associated with the sidelink process may be released if the transmission resource conditions are met. Thereafter, the MAC layer of the terminal may perform transmission resource (re)selection and perform a procedure for allocating the newly selected SL grant to the selected resource pool through new resource selection and reservation.

[0180] Further, as an example, if consecutive LBT failures are detected on a resource pool basis, the UE may perform a switching operation to another resource pool that partially or completely overlaps with the frequency resources in the SL BWP. As a specific example, the UE's MAC layer may select a resource pool, select single / multiple MAC PDU resources, generate a selected SL grant, and associate it with the sidelink process. The UE may perform an LBT operation before transmitting in an unlicensed band, and if consecutive LBT failures occur, consecutive LBT failures may occur in the resource pool. The UE may determine that the selected resources in the selected resource pool can no longer be maintained and may select a new resource pool. Therefore, the UE may select resources for single / multiple MAC PDUs, generate a new selected SL grant, and associate it with the sidelink process.

[0181] FIG. 23 illustrates a case where consecutive LBT failures are performed in resource pool units, which is applicable to the present disclosure. Referring to FIG. 23, the MAC layer of the UE may receive a candidate resource set from the physical layer of the UE. The MAC layer of the UE may select resource pool 2 based on the candidate resource set, select resources for initial transmission or retransmission in the selected resource pool 2 by considering single / multiple MAC PDUs, generate a selected SL grant for the resources, and associate the resources with the sidelink process. Here, if consecutive LBT failures occur in resource pool 2, the UE may select one of resource pool 0 or resource pool 1, which partially or completely overlaps with resource pool 2 in the frequency aspect, within the SL BWP. The UE may then receive a candidate resource set for initial transmission or retransmission from the physical layer by considering single / multiple MAC PDUs, select resources based on the candidate resource set, generate a selected SL grant for the resources, and associate the resources with the sidelink process.

[0182] 24 is a diagram illustrating a resource pool selection operation that can be applied to the present disclosure. Referring to FIG. 24, a terminal needs to select a resource pool in which consecutive LBT failures do not occur. As an example, if consecutive LBT failures are detected on a resource pool basis, the terminal may detect consecutive LBT failures in resource pool 1 (2410) and resource pool 3 (2430). However, this is merely a configuration for convenience of explanation and is not limited thereto. Here, the MAC layer of the terminal may select one of resource pool 2 (2420) and resource pool 4 (2440) in which consecutive LBT failures do not occur.

[0183] 25 is a diagram illustrating a method for detecting consecutive LBT failures on a resource pool basis, which may be applied to the present disclosure. Referring to FIG. 25, the MAC layer of a terminal operating in Mode 2, in which the terminal directly selects sidelink communication resources, may determine to generate single / multiple MAC PDUs and perform operations based on the determination.

[0184] The MAC layer of the terminal may select a resource pool and select one resource for an initial transmission or a retransmission opportunity (step 1, S2510). As an example, the MAC layer of the terminal may select a resource pool in which consecutive LBT failures do not occur. As a specific example, unlike selecting a resource pool depending on whether a PSFCH is configured and taking into account HARQ feedback enable / disable of data generated on the LCH, the MAC layer of the terminal may select a specific resource pool depending on whether a PSFCH is configured from among resource pools in which consecutive LBT failures do not occur, but is not limited thereto.

[0185] Thereafter, the UE MAC layer may determine whether consecutive LBT failures have occurred in the selected resource pool (step 2, S2520). If consecutive LBT failures have not occurred, the UE MAC layer may determine whether consecutive LBT failures have occurred in the continuously selected resource pool. On the other hand, if consecutive LBT failures have occurred in a specific selected resource pool, the UE MAC layer may determine whether a resource pool in which consecutive LBT failures have not occurred exists in the SL BWP (step 3, S2530). For example, if one or more resource pools in which consecutive LBT failures have not occurred exist in the SL BWP, the UE MAC layer may perform the resource pool and resource selection procedure again. On the other hand, if there is no resource pool in which consecutive LBT failures have not occurred in the SL BWP, the UE may generate an SL radio link failure (RLF) and release the PC5-RRC connection since there is no resource pool that can be selected in the SL BWP (step 4, S2540).

[0186] As another example, the operation of step 4 can be replaced with another operation. If there is no resource pool in which consecutive LBT failures in an SL BWP do not occur, an SL RLF may not occur. As a specific example, if SL carrier aggregation operation is activated in the UE, if there is no resource pool in which consecutive LBT failures in an SL BWP do not occur on a specific carrier, the UE may report consecutive LBT failures that occurred on a specific carrier to other carriers and configure the SL BWP of the specific carrier differently.

[0187] For example, the detection of consecutive LBT failures may be performed in units of RB sets or resource pools, as described above. Here, the UE may perform consistent LBT failure reporting for recovery from consecutive LBT failures. As a specific example, a Mode 1 UE controlled by a base station may transmit an SL LBT failure MAC CE to the base station. Also, if a Mode 2 UE in which the UE controls sidelink communication performs communication based on SL carrier aggregation, the UE may transmit an SL LBT failure MAC CE through other activated SL carriers.

[0188] Figure 26 is a diagram showing an SL LBT failure MAC CE that can be applied to the present disclosure. Referring to Figure 26(a), a MAC CE fixed at one octet can include eight C-fields. Here, C i can be set based on the unit for detecting consecutive LBT failures. As a specific example, when consecutive LBT failures are detected in units of RB sets, C i can be indicated as an RB set index, and the presence or absence of consecutive LBT failures can be indicated based on the RB set index. For example, if there are eight RB sets in an SL BWP and consecutive LBT failures occur in RB set 1, RB set 3, and RB set 5, when there are eight RB sets and consistent LBT failures occur in RB sets 1, 3, and 5, the C1, C3, and C5 fields may be set to 1 and the remaining C fields may be set to 0.

[0189] As another example, if consecutive LBT failures are detected in a resource pool, ican be indicated as a resource pool index, and the presence or absence of consecutive LBT failures can be indicated based on the resource pool index. As a specific example, if there are five resource pools in an SL BWP and consecutive LBT failures occur in resource pool 0 and resource pool 1, the C0 and C1 fields may be set to 1, and the remaining C fields may be set to 0.

[0190] As another example, referring to FIG. 26(b), the MAC CE may have a fixed format including four octets, and the C field may include 32. Therefore, when the number of RB sets or resource pools is greater than eight, the MAC CE can be used. As an example, SL carrier aggregation can use multiple SL carriers, and the number of RB sets or resource pools used may increase accordingly. In consideration of the above, the MAC CE may be configured with four octets, but is not limited to this embodiment.

[0191] For example, the C field index may be configured by a higher layer for each RB set or resource pool. As a specific example, when consecutive LBT failures are detected for each RB set, a case may be considered in which an SL BWP including four RB sets is activated for SL carrier 1 and SL carrier 2. However, this is merely an example for convenience of explanation and is not limiting. Here, the four RB sets in SL carrier 1 may correspond to C field indexes C0 to C3. Furthermore, the four RB sets in SL carrier 2 may correspond to C field indexes C4 to C7.

[0192] As another example, consider a case where consecutive LBT failures are detected in resource pool units, and an SL BWP including four resource pools is activated on SL carrier 1. However, this is merely an example for convenience of explanation and is not limiting. Here, the four resource pools on SL carrier 1 may correspond to C field indexes C0 to C3. Furthermore, the four resource pools on SL carrier 2 may correspond to C field indexes C4 to C7.

[0193] FIG. 27 is a diagram illustrating an SL LBT failure MAC CE that takes into account SL carrier aggregation, which can be applied to the present disclosure. Referring to FIG. 27, unlike FIG. 26, each octet in the MAC CE can include a 2-bit identifier (ID) and a 6-bit C field. Here, the identifier can be, but is not limited to, an SL BWP ID or an SL carrier ID. As a specific example, when carrier aggregation is performed through two SL carriers, there can be two activated carriers or SL BWPs. Therefore, the ID can indicate and distinguish the two SL carriers or SL BWPs using one bit. As another example, when carrier aggregation is performed through four SL carriers, there can be four activated carriers or SL BWPs. Therefore, the ID can indicate and distinguish the four SL carriers or SL BWPs using two bits.

[0194] For example, an identifier present before the C field within one octet can be used to distinguish RB sets or resource pools for consecutive LBT failure reports. As a specific example, referring to FIG. 27(a), the MAC CE may be fixed at one octet. As another example, referring to FIG. 27(b), the MAC CE may be fixed at four octets. As another example, referring to FIG. 27(c), the MAC CE may be variably configured based on the number of SL carriers or SL BWPs (N) that need to be distinguished, and is not limited to a specific form.

[0195] As an example, the identifier has been described above as an SL carrier ID or an SL BWP ID, but is not limited thereto and may be an identifier for distinguishing between multiple SL carriers. As another example, the identifier is configured with two bits, but is not limited thereto and may be configured with more bits. For example, when distinguishing between multiple SL carriers or SL BWPs, the number of identifier bits may increase. As another example, the C field is not limited to six bits within one octet and may be configured with more than six bits, and is not limited to a specific form.

[0196] FIG. 28 illustrates an SL LBT failure MAC / CE reporting operation to which the present disclosure may be applied. Referring to FIG. 28, terminal 1 (2810) may be controlled by a base station 2820 to perform scheduling through downlink control information (DCI) format 3_0. As another example, terminal 1 (2810) may be controlled by terminal 2 (2820) to perform scheduling through sidelink control information (SCI) format 1-A. As a specific example, when terminal 1 (2810) operates in mode 1 in which sidelink communication is controlled by a base station, terminal 1 (2810) may receive DCI format 3_0 and be controlled to perform PSCCH / PSSCH scheduling. Here, terminal 1 (2810) may perform an LBT operation before transmitting based on an unlicensed band. Referring to FIG. 28, if LBT failure reaches a preset threshold before terminal 1 (2810) transmits scheduled resources, the terminal may generate a sidelink consistent LBT failure. For example, the SL consecutive LBT failure detection unit may be an RB set or a resource pool, as described above. Terminal 1 (2810) may report consecutive LBT failures to base station 2820 based on the LBT failure detection unit. Here, the resource pool or PSCCH / PSSCH resources indicated by DCI format 3_0 newly received by the terminal may not include resources in the resource pool or RB set reported via the SL LBT failure MAC CE.

[0197] As another example, when terminal 2 (2820) operates in mode 2 that controls sidelink communication, terminal 1 (2810) receives SCI format 1-A from terminal 2 (2820), which is the transmitting terminal, and based on this, transmits PSSCH and 2 ndThe SCI can be scheduled. For example, if HARQ feedback is activated, the terminal 1 (2810), which is the receiving terminal, may need to perform an LBT procedure before transmitting a PSFCH. Here, if the LBT failure reaches a certain threshold, the terminal 1 (2810) may generate SL consecutive LBT failures. For example, the SL consecutive LBT failure detection unit may be an RB set or a resource pool, as described above. The terminal 1 (2810) may report consecutive LBT failures to the terminal 2 (2820) through an SL LBT failure MAC CE based on the LBT failure detection unit. Thereafter, the terminal 2 (2820) may transmit SCI format 1-A without selecting a resource from the RB set or resource pool reported by the terminal 1 (2810).

[0198] As another example, when the terminal 1 (2810) operates in mode 2 controlling sidelink communication, the terminal 1 (2810) becomes a transmitting terminal and can cause the terminal 2 (2820) to schedule the PSSCH and the second SCI through SCI format 1-A. As an example, the terminal 1 (2810) can perform an LBT procedure and detect an LBT failure before performing an SL transmission (e.g., S-SSB, SCI). Here, if the LBT failure reaches a certain threshold, the terminal 1 (2810) can generate an SL consecutive LBT failure. As an example, the SL consecutive LBT failure detection unit can be an RB set or a resource pool, as described above. The terminal 1 (2810) can report consecutive LBT failures to the terminal 2 (2820) through an SL LBT failure MAC CE based on the LBT failure detection unit. Thereafter, the terminal 2 (2820) can transmit SCI format 1-A without selecting a resource from the RB set or resource pool reported by the terminal 1 (2810). In addition, terminal 2 (2820) can recognize that SCI format 1-A transmission is not being performed from terminal 1 (2810) in the RB set or resources in the resource pool reported through the SL LBT failure MAC CE, and does not need to monitor the PSCCH in the resource pool.

[0199] FIG. 29 is a diagram illustrating a method for transmitting an SL LBT failure MAC CE that may be applied to the present disclosure. Referring to FIG. 29, a terminal may perform an LBT before performing an SL transmission (step 1, S2910). For example, the terminal may perform an LBT taking into account an unlicensed band before performing an SL transmission for which the base station schedules or the terminal itself schedules time and frequency resources. If the LBT fails (step 2, S2920), the terminal may determine that the LBT is successful if the energy level received over a specific time interval is lower than a threshold, and may initialize an SL LBT counter to 0. On the other hand, if the energy level received over a specific time interval is higher than the threshold, the terminal may determine that the LBT is unsuccessful and increment the SL LBT counter (S2930). For example, the MAC layer of the terminal may increment the SL LBT counter by one based on the LBT failure. If the SL LBT counter reaches its maximum counter value (step 4, S2940), consecutive SL LBT failures may occur. For example, if the SL LBT counter is greater than the maximum counter at a set threshold, the UE may generate SL consecutive LBT failures and transmit an SL LBT failure MAC CE (step 5, S2950). For example, the UE may transmit an SL LBT failure MAC CE to a base station or another UE regarding SL consecutive LBT failures detected in units of an RB set or resource pool. For example, if the transmitting UE operates in mode 1, the UE may transmit an SL LBT failure MAC CE to a base station and one or more receiving UEs. Conversely, if the transmitting UE operates in mode 2, the UE may transmit an SL LBT failure MAC CE to one or more receiving UEs. Conversely, if the SL LBT counter is less than the maximum counter at a set threshold, the UE may proceed with step 1 of performing LBT for another SL transmission.

[0200] FIG. 30 is a flowchart illustrating a method for performing sidelink communication based on consecutive LBT failures according to the present disclosure. The wireless user device may select a resource pool and resources for sidelink communication based on a resource pool and resource selection procedure (S3010). The wireless user device then performs an LBT procedure using the selected resource pool and resources based on the sidelink unlicensed band (S3020) and checks whether consecutive LBT failures have occurred based on the LBT procedure (S3030). If consecutive LBT failures have occurred, the wireless user device may select resources for sidelink communication based on a transmission resource selection procedure (S3040). The occurrence of consecutive LBT failures is checked for each resource block (RB) set, and the resource pool may include multiple RB sets. For example, if consecutive LBT failures have occurred in a first RB set among multiple RB sets included in a resource pool and consecutive LBT failures have not occurred in a second RB set among the multiple RB sets included in the resource pool, the wireless user device may perform a resource selection procedure using the second RB set to select resources for sidelink communication.

[0201] As another example, if consecutive LBT failures occur in the first RB set but consecutive LBT failures do not occur in the second RB set, the MAC layer of the wireless user equipment may release the sidelink grant selected based on the resource selection procedure and select resources for sidelink communication included in the second RB set.

[0202] As another example, if consecutive LBT failures occur in the first RB set but not in the second RB set, the MAC layer of the wireless user equipment may transmit consecutive LBT failure information to the physical layer of the wireless user equipment. The physical layer of the wireless user equipment may determine a candidate resource set based on the consecutive LBT failure information and transmit the determined candidate resource set to the MAC layer of the wireless user equipment. The MAC layer of the wireless user equipment may select at least one resource from the candidate resource set as a resource for sidelink communication, as described above.

[0203] As another example, whether consecutive LBT failures occur may be checked for each resource pool, and one sidelink bandwidth part (SL BWP) may include multiple resource pools. For example, if consecutive LBT failures occur in a first resource pool among the multiple resource pools included in the SL BWP and consecutive LBT failures do not occur in a second resource pool among the multiple resource pools included in the SL BWP, the wireless user equipment may select the second resource pool based on a resource pool and resource selection procedure and perform a resource selection procedure in the second resource pool to select resources for sidelink communication. As another example, if consecutive LBT failures occur in all multiple resource pools included in the SL BWP, the wireless user equipment may release connections with other wireless user equipment based on the SL RLF.

[0204] As another example, consecutive LBT failure reporting may be performed through an SL LBT failure MAC CE, and the C field of each of the SL LBT failure MAC CEs may be set based on consecutive LBT failure reporting units.

[0205] FIG. 31 is a diagram showing a base station apparatus and a terminal apparatus to which the present disclosure can be applied.

[0206] The base station device 3100 may include a processor 3120, an antenna unit 3112, a transceiver 3114, and a memory 3116.

[0207] The processor 3120 performs baseband-related signal processing and may include an upper layer processing unit 3130 and a physical layer processing unit 3140. The upper layer processing unit 3130 may process operations of a medium access control (MAC) layer, a radio resource control (RRC) layer, or higher layers. The physical layer processing unit 3140 may process operations of a physical (PHY) layer (e.g., uplink receive signal processing, downlink transmit signal processing). In addition to performing baseband-related signal processing, the processor 3120 may control the overall operation of the base station device 3100.

[0208] The antenna unit 3112 may include one or more physical antennas, and when multiple antennas are included, it may support MIMO (Multiple Input Multiple Output) transmission and reception, and may also support beamforming.

[0209] The memory 3116 can store information processed by the processor 3120, software associated with the operation of the base station device 3100, an operating system, applications, etc., and can include components such as buffers.

[0210] The processor 3120 of the base station device 3100 may be configured to implement the operation of the base station in the embodiments described herein.

[0211] The terminal device 3150 may include a processor 3170, an antenna unit 3162, a transceiver 3164, and a memory 3166. As an example, in the present invention, the terminal device 3150 can communicate with the base station device 3100. As another example, in the present invention, the terminal device 3150 can perform sidelink communication with another terminal device. That is, the terminal device 3150 of the present invention refers to a device that can communicate with at least one of the base station device 3100 and another terminal device, and is not limited to communication with a specific device.

[0212] The processor 3170 performs baseband-related signal processing and may include an upper layer processing unit 3180 and a physical layer processing unit 3190. The upper layer processing unit 3180 may process operations of the MAC layer, the RRC layer, or higher layers. The physical layer processing unit 3190 may process operations of the PHY layer (e.g., downlink receive signal processing, uplink transmit signal processing). In addition to performing baseband-related signal processing, the processor 3170 may control the overall operation of the terminal device 3150.

[0213] The antenna unit 3162 may include one or more physical antennas, and when multiple antennas are included, may support MIMO transmission and reception, and may also support beamforming.

[0214] The memory 3166 can store information processed by the processor 3170, software associated with the operation of the terminal device 3150, an operating system, applications, etc., and can include components such as buffers.

[0215] A terminal device 3150 according to an embodiment of the present invention may be associated with a vehicle. For example, the terminal device 3150 may be built into, located in, or located on the vehicle. The terminal device 3150 according to the present invention may be the vehicle itself. The terminal device 3150 according to the present invention may be at least one of a wearable terminal, an AV / VR terminal, an IoT terminal, a robot terminal, and a public safety terminal. The terminal device 3150 to which the present invention is applicable may include any of various types of communication devices that support interactive services using a sidelink for services such as Internet connection, service execution, navigation, real-time information, autonomous driving, safety, and hazard diagnosis. The terminal device 3150 may also include any type of communication device that can perform a sidelink operation, such as an AR / VR device, or a sensor that performs a relay operation.

[0216] Here, vehicles to which the present invention is applied may include autonomous vehicles, semi-autonomous vehicles, non-autonomous vehicles, etc. Meanwhile, although the terminal device 3150 according to an example of the present invention is described as being associated with a vehicle, one or more of the UEs may not be associated with a vehicle. This is merely an example, and the application of the present invention should not be construed as being limited by the described example.

[0217] In addition, the terminal device 3150 according to an embodiment of the present invention may include various types of communication devices that can cooperate to support an interactive service using a sidelink. That is, the terminal device 3150 can be used not only to directly support an interactive service using a sidelink, but also as a cooperating device to support an interactive service using a sidelink.

[0218] Further, as an example, the terminal device 3150 may select a resource pool and resources for sidelink communication based on a resource pool and resource selection procedure. Then, the terminal device 3150 may perform an LBT procedure on the resource pool and resources selected based on the sidelink unlicensed band and check whether consecutive LBT failures occur based on the LBT procedure. If consecutive LBT failures occur, the terminal device 3150 may select resources for sidelink communication based on a transmission resource selection procedure. Here, whether consecutive LBT failures occur is checked for each resource block (RB) set, and the resource pool may include multiple RB sets. As an example, if consecutive LBT failures occur in a first RB set among multiple RB sets included in a resource pool and consecutive LBT failures do not occur in a second RB set among the multiple RB sets included in the resource pool, the terminal device 3150 may perform a resource selection procedure on the second RB set to select resources for sidelink communication.

[0219] As another example, if consecutive LBT failures occur in the first RB set but consecutive LBT failures do not occur in the second RB set, the MAC layer of the terminal device 3150 can release the sidelink grant selected based on the resource selection procedure and select resources for sidelink communication included in the second RB set.

[0220] As another example, if consecutive LBT failures occur in the first RB set but not in the second RB set, the MAC layer of the terminal device 3150 may transmit consecutive LBT failure information to the physical layer of the terminal device 3150. The physical layer of the terminal device 3150 may determine a candidate resource set based on the consecutive LBT failure information and transmit the determined candidate resource set to the MAC layer of the terminal device 3150. 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, as described above.

[0221] As another example, whether consecutive LBT failures occur is checked for each resource pool, and one sidelink bandwidth part (SL BWP) may include multiple resource pools. For example, if consecutive LBT failures occur in a first resource pool among the multiple resource pools included in the SL BWP and consecutive LBT failures do not occur in a second resource pool among the multiple resource pools included in the SL BWP, the terminal device 3150 may select a second resource pool based on a resource pool and resource selection procedure and perform a resource selection procedure in the second resource pool to select resources for sidelink communication. As another example, if consecutive LBT failures occur in all multiple resource pools included in the SL BWP, the terminal device 3150 may release connections with other terminal devices 3150 based on the SL RLF.

[0222] As another example, consecutive LBT failure reporting may be performed through an SL LBT failure MAC CE (medium access control element), and the C field of each of the SL LBT failure MAC CEs may be set based on consecutive LBT failure reporting units.

[0223] Furthermore, various embodiments of the present disclosure may be implemented using hardware, firmware, software, or a combination thereof, etc. In the case of a hardware implementation, the implementation may be using 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 processors, controllers, microcontrollers, microprocessors, etc.

[0224] The scope of the present disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) that cause the operations of the methods of the various embodiments to be performed on a device or computer, as well as non-transitory computer-readable media on which such software or instructions are stored and which can be executed on a device or computer.

[0225] The various embodiments of the present disclosure do not enumerate all possible combinations, but are intended to describe representative aspects of the present disclosure, and the matters described in the various embodiments may be applied independently or in combination of two or more. [Industrial Applicability]

[0226] The above may also be applied to other systems.

Claims

1. A wireless user equipment (UE) that operates in a sidelink unlicensed band via LBT in a wireless communication system, comprising: at least one antenna for transmitting and receiving one or more radio signals; at least one processor; and a memory that stores instructions for the wireless user device when executed by the at least one processor; The operation of the wireless user equipment is to: selecting a resource pool and resources for sidelink communication based on a resource pool and resource selection procedure; performing a listen before talk (LBT) procedure on the resource pool and the resources selected based on the sidelink unlicensed spectrum; determining whether a consistent LBT failure has occurred based on the LBT procedure; When the consecutive LBT failures occur, the wireless user equipment selects resources for the sidelink communication based on a transmission resource selection procedure.

2. The occurrence of the consecutive LBT failures is checked for each RB (resource block) set, 2. The wireless user equipment (UE) of claim 1, wherein the resource pool includes a plurality of RB sets, and when the consecutive LBT failures occur in a first RB set among the plurality of RB sets included in the resource pool and the consecutive LBT failures do not occur in a second RB set among the plurality of RB sets included in the resource pool, the wireless user equipment (UE) performs the resource selection procedure in the second RB set to select the resources for the sidelink communication.

3. 3. The wireless user equipment according to claim 2, wherein, when the consecutive LBT failures occur in the first RB set but the consecutive LBT failures do not occur in the second RB set, a medium access control (MAC) layer of the wireless user equipment releases the sidelink grant selected based on the resource selection procedure and selects the resources for the sidelink communication included in the second RB set.

4. 3. The wireless user equipment according to claim 2, wherein, when the consecutive LBT failures occur in the first RB set but the consecutive LBT failures do not occur in the second RB set, the MAC layer of the wireless user equipment transmits consecutive LBT failure information to the physical layer of the wireless user equipment, the physical layer of the wireless user equipment determines a candidate resource set based on the consecutive LBT failure information and transmits the determined candidate resource set to the MAC layer of the wireless user equipment, and the MAC layer of the wireless user equipment selects at least one resource from the candidate resource set as the resource for the sidelink communication.

5. The occurrence of the consecutive LBT failures is checked for each resource pool, One sidelink bandwidth part (SL BWP) includes multiple resource pools, 2. The wireless user equipment (UE) of claim 1, wherein, when the consecutive LBT failures occur in a first resource pool among the plurality of resource pools included in the SL BWP and the consecutive LBT failures do not occur in a second resource pool among the plurality of resource pools included in the SL BWP, the wireless user equipment (UE) selects the second resource pool based on the resource pool and a resource selection procedure, and performs a resource selection procedure in the second resource pool to select the resources for sidelink communication.

6. 6. The wireless user equipment according to claim 5, wherein when the consecutive LBT failures occur in all of the resource pools included in the SL BWP, the wireless user equipment releases its connection with other wireless user equipments based on a sidelink radio link failure (SL RLF).

7. 2. The wireless user equipment according to claim 1, wherein the successive LBT failure reporting is performed through an SL LBT failure MAC CE (medium access control element), and a C field of each of the SL LBT failure MAC CEs is set based on successive LBT failure reporting units.

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