Method and apparatus for performing sidelink communications over unlicensed spectrum

Abstract

In a wireless communication system, a wireless user device may receive configuration of at least one HARQ feedback transmission opportunity, transmit HARQ feedback based on the configured at least one HARQ feedback transmission opportunity, operate a sidelink DRX HARQ RTT timer based on the HARQ feedback transmission, and receive a retransmission grant when the sidelink DRX HARQ RTT timer expires.

Description

[Technical Field]

[0001] The present disclosure relates to a method and apparatus for performing sidelink communication over unlicensed spectrum in a wireless communication system. Specifically, the present disclosure relates to a method and apparatus for operating a hybrid automatic repeat request (HARQ) timer in sidelink unlicensed (SL-U) spectrum. [Background technology]

[0002] The International Telecommunication Union (ITU) is developing the International Mobile Telecommunication (IMT) framework and standards, and has recently been discussing fifth-generation (5G) communications 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 operating a HARQ timer in SL-U.

[0008] The technical problem of the present disclosure relates to a method and apparatus for operating a HARQ timer based on a PSFCH (physical sidelink feedback channel) transmission opportunity in SL-U.

[0009] 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]

[0010] According to one aspect of the present disclosure, a wireless user equipment (UE) operating in a sidelink unlicensed spectrum in a wireless communication system includes at least one antenna for transmitting and receiving one or more wireless signals, at least one processor, and a memory for storing instructions for the wireless user equipment, when executed by the at least one processor, to: configure at least one hybrid automatic repeat and request (HARQ) feedback transmission opportunity; transmit HARQ feedback based on the configured at least one HARQ feedback transmission opportunity; operate a sidelink discontinuous reception (DRX) HARQ round trip time (RTT) timer based on the HARQ feedback transmission; and receive a retransmission grant upon expiration of the sidelink DRX HARQ RTT timer.

[0011] According to one aspect of the present disclosure, if the sidelink DRX HARQ RTT timer expires and the data for the sidelink process is not successfully decoded or the HARQ feedback information is a NACK, a retransmission grant can be received based on the sidelink DRX HARQ retransmission timer.

[0012] According to one aspect of the present disclosure, at least one HARQ feedback transmission opportunity may be configured in multiple locations based on at least one of a semi-static physical sidelink feedback channel (PSCCH) configuration and a dynamic PSFCH resource indication.

[0013] According to one aspect of the present disclosure, the sidelink DRX HARQ RTT timer may operate based on a HARQ feedback transmission opportunity that is successful among multiple HARQ feedback transmission opportunities.

[0014] According to one aspect of the present disclosure, the sidelink DRX HARQ RTT timer can operate based on a specific HARQ feedback transmission opportunity among multiple HARQ feedback transmission opportunities.

[0015] According to one aspect of the present disclosure, the at least one HARQ feedback transmission opportunity may be configured as one.

[0016] According to one aspect of the present disclosure, one HARQ feedback transmission opportunity can be indicated in a physical sidelink shared channel (PSSCH) as a resource for HARQ feedback.

[0017] According to one aspect of the present disclosure, the sidelink DRX HARQ RTT timer can operate based on resources for HARQ feedback in the PSSCH. [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 for operating a HARQ timer in SL-U can be provided.

[0020] According to the present disclosure, it is possible to provide a method for operating a HARQ timer based on a PSFCH transmission opportunity in SL-U.

[0021] 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]

[0022] [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 applicable to the present disclosure. [Figure 13] FIG. 13 illustrates 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 configuring multiple PSFCH transmission opportunities and a method for configuring a sidelink DRX timer accordingly, according to the present disclosure. [Figure 18] FIG. 18 illustrates a method for configuring multiple HARQ feedback transmission opportunities through a semi-statically configured PSFCH configuration according to the present disclosure and performing sidelink DRX timer operation accordingly. [Figure 19] FIG. 19 illustrates a method for configuring multiple HARQ feedback transmission opportunities using semi-statically configured PSFCH occasions and designated PSFCH resources, and operating a sidelink DRX timer based on the configured PSFCH occasions and designated PSFCH resources, as applied to the present disclosure. [Figure 20] FIG. 20 is a diagram illustrating designated PSSCH resources for HARQ feedback considering a single HARQ feedback transmission opportunity as applied to the present disclosure. [Figure 21] FIG. 21 is a diagram illustrating a HARQ feedback transmission opportunity bundling operation to which the present disclosure is applied. [Figure 22]FIG. 22 is a flowchart illustrating the operation of a wireless user equipment to which the present disclosure can be applied. [Figure 23] FIG. 23 is a diagram showing a base station apparatus and a terminal apparatus to which the present disclosure can be applied. BEST MODE FOR CARRYING OUT THE INVENTION

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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).

[0034] 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.

[0035] First, a brief description will be given of the physical resource structure of the NR system to which the present invention is applied.

[0036] FIG. 1 is a diagram for explaining an NR frame structure to which the present disclosure can be applied.

[0037] 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.

[0038] 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.

[0039] 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:

[0040]

number

[0041] 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. 39936 JPEG2026508721000003.jpg53 is 20.327μs, 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.

[0042] FIG. 2 is a diagram illustrating an NR resource structure to which the present disclosure may be applied.

[0043] 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.

[0044] 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.

[0045]

number

[0046] 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.

[0047] 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.

[0048] Table 1 below shows examples of pneumoradio supported by the NR system.

[0049] [Table 1]

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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).

[0054] 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.

[0055] 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).

[0056] [Table 2]

[0057] 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.

[0058] [Table 3]

[0059] 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.

[0060] 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.

[0061] [Table 4]

[0062] 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.

[0063] 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. This allows new features to 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.

[0064] 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.

[0065] [Table 5]

[0066] 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.

[0067] 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.

[0068] Here, NR V2X capability is not necessarily limited to supporting only V2X services, and may optionally support the use of a certain V2X RAT.

[0069] 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).

[0070] 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.

[0071] 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.

[0072] FIG. 3 is a diagram illustrating an NR sidelink slot structure to which the present disclosure can be applied.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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).

[0077] 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.

[0078] 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.

[0079] [Table 6]

[0080] [Table 7-1] [Table 7-2] [Table 7-3]

[0081] NOTE 1: For Standardized PQI to QoS characteristics mapping, the table will be extended / updated to support service requirements for other identified V2X services.

[0082] NOTE 2: The PQIs may be used for services other than V2X.

[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, the set of sidelink slots within one resource pool application period (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., when the number of RBs does not match 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. JPEG2026508721000016.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. JPEG2026508721000018.jpg972 and 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 JPEG2026508721000019.jpg1326 and the end CRB is JPEG2026508721000020.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 JPEG2026508721000021.jpg1322 will interfere with the wireless bandwidth.

[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 JPEG2026508721000022.jpg970 That is, the RBS index s can be JPEG2026508721000023.jpg may be a resource block having a size of 1323, JPEG2026508721000024.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 JPEG2026508721000028.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 configured bit 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 end of the PSFCH resource to receive a retransmission grant.

[0127] For example, if HARQ feedback is enabled within a resource pool in which a PSFCH is configured and a retransmission resource is configured within the SCI, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) may be derived from the next retransmission resource within the SCI. As another example, if HARQ feedback is disabled and there are no retransmission resources within 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 within 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 within 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 a retransmission resource does not exist 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) is composed of four, and the PSFCH occasion can be composed of four slots by sl-PSFCH-period. Here, the PSFCH slots associated with one PSFCH occasion are JPEG2026508721000029.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. JPEG2026508721000030.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 JPEG2026508721000031.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 i JPEG2026508721000033.jpg1346 means the slot number associated with the PSFCH, and j (0 ≤ j <N subch ) can mean the number of the subchannel. JPEG2026508721000034.jpg1335 is PRB for HARQ feedback JPEG2026508721000035.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. JPEG2026508721000036.jpg1326 is for each subchannel of the slot associated with the PSFCH JPEG2026508721000037.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 JPEG2026508721000038.jpg1326 is 80, then there will be 5 PRBs for each subchannel. JPEG2026508721000039.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. JPEG2026508721000040.jpg1335, each PRB is the number of CS (cyclic shift) pairs If there are two JPEG2026508721000041.jpg990s and sl-PSFCH-CandidateResourceType is set to "startSubCH" JPEG2026508721000042.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: JPEG2026508721000044.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 an index derived from Equation 8 below. As another example, when sl-PSFCH-CandidateResourceType is set to allocSubCH, JPEG2026508721000045.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, continuous transmission in unlicensed bands may be restricted in certain regions (e.g., Europe, Japan). 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. Also, 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 reduces 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] 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.

[0151] 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.

[0152] The following describes the operation of the HARQ DRX timer in sidelink-unlicensed (SL-U) operation, taking the above points into consideration. As an example, a UE may perform an LBT procedure in SL-U and perform sidelink transmission in COT if the LBT is successful. On the other hand, the UE may perform an LBT procedure in SL-U and fail to occupy the channel, thereby failing to perform sidelink transmission. The following describes the operation of the HARQ DRX timer, taking the above situation into consideration.

[0153] For example, a terminal can perform sidelink transmission by performing an LBT operation in an unlicensed band and occupying a channel based on successful LBT. However, if the terminal is unable to occupy the channel, it may be unable to perform sidelink transmission. In other words, if the terminal fails LBT, it may be unable to perform HARQ feedback transmission on the PSFCH. Furthermore, in unlicensed bands, other communication technologies (e.g., Wi-Fi) coexist and must use the channel equally. Therefore, requirements such as the maximum channel occupancy time (MCOT) can be taken into consideration, as described above. As a specific example, if the received signal strength through the LBT procedure does not exceed a certain power threshold, the terminal can occupy and use the channel for a limited time.

[0154] Here, the existing HARQ feedback operation may be configured semi-statically. Although the PSFCH occasion for HARQ feedback may be configured semi-statically, improvements to this may be required in consideration of the SL-U operation. As an example, the HARQ feedback operation may support an operation of configuring multiple consecutive or non-consecutive PSFCH transmission opportunities in consideration of the SL-U. As another example, the HARQ feedback operation may support a PSFCH (dedicated PSFCH) resource indication operation designated in consideration of the SL-U. As another example, the HARQ feedback operation may support a PSCCH (dedicated PSSCH) resource indication operation designated in consideration of the SL-U. However, this is merely an example and is not limited thereto.

[0155] For example, the multiple PSFCH transmission opportunities taking into account SL-U may refer to one or more semi-statically configured PSFCH occasions. As another example, the multiple PSFCH transmission opportunities taking into account SL-U may refer to one or more semi-statically configured PSFCH occasions and a dynamically indicated dedicated PSFCH resource. For example, the dynamically indicated HARQ feedback resource may be a method of indicating the HARQ feedback resource in sidelink control information (SCI). Here, the SCI may indicate a specific resource or a PSSCH resource among the semi-statically configured PSFCH occasions as the HARQ feedback resource.

[0156] As a specific example, a semi-static PSFCH configuration or a semi-static PSFCH configuration and a dynamic PSFCH / PSSCH resource indication operation can be considered as multiple HARQ feedback transmission opportunities taking SL-U into consideration, which may be as shown in Table 11 below. Furthermore, a dynamic PSSCH resource indication for HARQ feedback can be considered as a single HARQ feedback transmission opportunity. Furthermore, a semi-static PSFCH configuration can be considered as a single HARQ feedback transmission opportunity, which may be as shown in Table 11 below.

[0157] [Table 11]

[0158] Furthermore, sidelink DRX timer (sl-drx-HARQ-RTT-Timer, sl-drx-RetransmissionTimer) operation taking into account additional PSFCH transmission opportunities may be necessary, and this will be described.

[0159] As an example, FIG. 17 illustrates a method for configuring multiple PSFCH transmission opportunities and a method for configuring a sidelink DRX timer based thereon, according to the present disclosure. Referring to FIG. 17, PSFCH resources 1710, 1720, and 1730 may be semi-statically configured in sidelink slots. The intervals between the PSFCH resources 1710, 1720, and 1730 may be semi-statically configured according to a parameter (sl-PSFCH-period) indicating the PSFCH period. As an example, the PSFCH interval in FIG. 17 may be configured with two slots. Specifically, the PSFCH resources may be configured in sidelink slot numbers where the "logical sidelink slot number modulo sl-PSFCH-Period" is 0. However, this is merely a configuration for convenience of explanation, and the present disclosure is not limited to this.

[0160] Here, the sidelink DRX timer may be configured to operate variably. The sidelink DRX timer may be set to reduce the power consumption of the receiving terminal, taking into account the operation of transmitting and receiving a retransmission grant between the transmitting terminal and the receiving terminal. For example, the sidelink DRX timer needs to operate at a specific time point among multiple HARQ feedback transmission opportunities in consideration of the above. The multiple HARQ feedback transmission opportunities may be opportunities for the transmitting terminal to determine ACK / NACK for sidelink data based on the HARQ feedback. The transmitting terminal may generate a retransmission grant considering the time point at which HARQ feedback information is actually received among the HARQ feedback transmission opportunities. Therefore, the receiving terminal may operate the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) in the sidelink DRX timer after the time point at which HARQ feedback transmission is successful among the HARQ feedback transmission opportunities. Thereafter, the receiving terminal may operate the sidelink DRX retransmission timer (sl-drx-Retransmission Timer) in the sidelink DRX timer to receive a retransmission grant, depending on whether the received data has been successfully decoded. As an example, the sidelink DRX retransmission timer may be a timer for a maximum period until a sidelink retransmission is received.

[0161] As another example, when multiple HARQ feedback transmission opportunities are configured, the sidelink DRX timer operation may be fixed to a specific time point. For example, the transmitting terminal may not receive HARQ feedback within the configured multiple HARQ feedback transmission opportunities, and the transmitting terminal may not recognize the reason for the failure to receive HARQ feedback. As a specific example, if the receiving terminal fails LBT, the receiving terminal may not be able to transmit HARQ feedback to the transmitting terminal. As another example, the receiving terminal may not be able to transmit sidelink HARQ feedback through UL operation based on UL / SL prioritization operation. As another example, the receiving terminal may not be able to transmit HARQ feedback when the channel condition is poor, but this is not limiting.

[0162] In consideration of the above, the sidelink DRX timer may be configured to operate at a specific transmission opportunity among the configured multiple HARQ feedback transmission opportunities, and retransmission / reception of retransmission grants may be performed based on the configured transmission opportunity. As a specific example, the sidelink DRX timer may operate at the last transmission opportunity among the configured multiple HARQ feedback transmission opportunities. As another example, the sidelink DRX timer may operate at another transmission opportunity, and is not limited to a specific embodiment.

[0163] As another example, FIG. 18 illustrates a method for configuring multiple HARQ feedback transmission opportunities through a semi-statically configured PSFCH configuration applied to the present disclosure and performing a sidelink DRX timer operation based thereon. Referring to FIG. 18, a receiving terminal may receive SCI and data from a transmitting terminal through a PSCCH / PSSCH 1810 in slot n. The receiving terminal may perform HARQ feedback in slot n+4, which includes the first PSFCH occasion 1820 after two slots indicated by a parameter (e.g., sl-MinTimeGapPSFCH) set to the minimum time gap for the PSFCH. Also, if multiple HARQ feedback transmission opportunities are configured and activated in the terminal, the receiving terminal may perform the nth HARQ feedback transmission in a PSFCH occasion 1830 in slot n+6 using resources available for transmitting HARQ feedback.

[0164] For example, it may be necessary to configure the sidelink DRX timer operation taking the above-mentioned situation into consideration. Specifically, the sidelink DRX timer may be variably determined. The sidelink DRX timer may operate after transmitting HARQ feedback after the LBT procedure is successful among HARQ feedback transmission opportunities. Referring to FIG. 18, a case may be considered in which the receiving terminal fails to transmit HARQ feedback due to an LBT failure in the PSFCH occasion 1820 of slot n+4, but successfully transmits HARQ feedback due to an LBT success in the PSFCH occasion 1830 of slot n+6. However, this is merely an example for convenience of explanation and is not limited thereto. That is, the receiving terminal may transmit HARQ feedback in the PSFCH occasion 1830 of slot n+6. Here, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) of the sidelink DRX timer may operate after the PSFCH occasion 1830 in which the HARQ feedback is transmitted. When the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) expires, if the data of the corresponding sidelink process has not been successfully decoded or the HARQ feedback is a NACK, the receiving terminal can operate the sidelink DRX HARQ retransmission timer (sl-drx-HARQ-RetransmissionTimer) and expect to receive a retransmission grant through PSCCH monitoring.

[0165] As another example, the sidelink DRX timer may be fixed to operate after a specific HARQ feedback transmission opportunity among the HARQ feedback transmission opportunities. For example, the sidelink DRX timer may operate after the last HARQ feedback transmission opportunity. Referring to FIG. 18, a case may be considered in which HARQ feedback transmission is successful based on LBT success in the PSFCH occasion 1820 of slot n+4. However, even in the above case, since the sidelink DRX timer is fixed to operate after the last HARQ feedback transmission opportunity, the sidelink DRX HARQRTT timer (sl-drx-HARQ-RTT-Timer) may operate after the PSFCH occasion 1830 located in slot n+6 as the last HARQ feedback opportunity. When the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) expires, if the data of the corresponding sidelink process is not successfully decoded or the HARQ feedback is a NACK, the receiving terminal may operate the sidelink DRX HARQ retransmission timer (sl-drx-HARQ-RetransmissionTimer) and expect to receive a retransmission grant through PSCCH monitoring. As an example, although the description in FIG. 18 is based on the case where the number of HARQ feedback transmission opportunities is two, the present invention is not limited thereto, and more HARQ feedback transmission opportunities may be configured.

[0166] Furthermore, for example, various methods for indicating multiple HARQ feedback transmission opportunities may be configured. For example, consecutive PSFCH occasions may be indicated, and a fixed N number of PSFCH occasions may be indicated via RRC. That is, the receiving terminal may obtain HARQ feedback transmission opportunities at N consecutive PSFCH occasions starting from a specific PSFCH occasion.

[0167] As another example, when indicating non-consecutive PSFCH occasions, the UE may acquire an offset parameter for the n-th PSFCH occasion through RRC. As an example, the receiving UE may acquire an offset parameter for the second PSFCH occasion (e.g., sl-2ndMinTimeGapPSFCH) and acquire a HARQ feedback transmission opportunity based on the offset parameter. As another example, the UE may acquire the above-mentioned consecutive PSFCH occasions or offset values ​​through SCI rather than RRC, and is not limited to a specific form.

[0168] 19 illustrates a method for configuring multiple HARQ feedback transmission opportunities using semi-statically configured PSFCH occasions and designated PSFCH resources, and for operating a sidelink DRX timer based on the configured HARQ feedback transmission opportunities. For example, the designated PSFCH resource in FIG. 19 may be a specific physical resource block (PRB) in the semi-statically configured PSFCH occasion, or a specific resource in the PSSCH.

[0169] As a specific example, referring to FIG. 19(a), the designated PSFCH resource may be a specific PRB resource within a semi-statically configured PSFCH occasion. For example, the designated PSFCH resource may be indicated via an SCI, and the PSFCH resource may be added as a HARQ feedback transmission opportunity. For example, the sidelink DRX timer may operate after a specific HARQ feedback transmission opportunity among the HARQ feedback transmission opportunities in a fixed manner. For example, the sidelink DRX timer may operate after the last HARQ feedback transmission opportunity, but is not limited to this. In FIG. 19(a), the UE may receive an SCI and data over the PSCCH / PSSCH of slot n. The receiving UE may recognize that a PSFCH occasion 1910 located in slot n+4 is associated with the PSSCH received in slot n and is a HARQ feedback transmission opportunity. Furthermore, the receiving UE may recognize that a designated PSFCH resource 1920 indicated by the SCI is a HARQ feedback transmission opportunity.

[0170] That is, it can be recognized that the PSFCH occasion 1910 located in slot n+4 may be the first HARQ feedback transmission opportunity, and the PSFCH occasion 1920 located in slot n+8 may be the second HARQ feedback transmission opportunity. Here, as an example, the receiving terminal may fail to transmit HARQ feedback due to an LBT failure in the first HARQ feedback transmission opportunity 1910 located in slot n+4, but may succeed in the LBT and perform HARQ feedback transmission in the second HARQ feedback transmission opportunity 1920 located in slot n+8. However, this is merely an example for convenience of explanation, and the present invention is not limited to this.

[0171] The receiving terminal may operate a sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) using a sidelink DRX timer after performing HARQ feedback in slot n+8, which is the second and last PSFCH transmission, to receive a retransmission grant. When the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) expires, if data of the corresponding sidelink process has not been successfully decoded or the HARQ feedback is a NACK, the receiving terminal may operate a sidelink DRX HARQ retransmission timer (sl-drx-HARQ-RetransmissionTimer) to expect to receive a retransmission grant through PSCCH monitoring. Furthermore, as an example, the specified PSFCH resource may not be located earlier in time than the associated first PSFCH resource. As an example, since the PSFCH resource semi-statically configured by the network is set through sl-MinTimeGapPSFCH taking into account the PSFCH period and Tx / Rx switching time, the additionally specified PSFCH resource cannot take priority in time over the first PSFCH resource.

[0172] 19(b), the designated PSFCH resource may be designated within PSSCH resource 1930. As an example, the designated PSFCH resource within PSSCH resource 1930 may be indicated via SCI, and the designated PSFCH resource may be added as a HARQ feedback transmission opportunity.

[0173] In FIG. 19(b), the UE may receive SCI and data via the PSCCH / PSSCH of slot n. The receiving UE may recognize that the PSFCH occasion 1910 located in slot n+4 is an HARQ feedback transmission opportunity associated with the PSSCH received in slot n. Furthermore, the receiving UE may recognize that a designated PSFCH resource within the PSSCH resource 1930 indicated by the SCI is an HARQ feedback transmission opportunity. That is, the receiving UE may recognize that the PSFCH occasion 1910 located in slot n+4 may be the first HARQ feedback transmission opportunity, and that the PSFCH resource within the PSSCH 1930 located in slot n+6 is the second HARQ feedback transmission opportunity. Here, as an example, the receiving UE may fail to transmit HARQ feedback due to an LBT failure in the first HARQ feedback transmission opportunity 1910 located in slot n+4, but may successfully complete the LBT and perform HARQ feedback transmission in the second HARQ feedback transmission opportunity located in slot n+6. However, this is merely an example for the sake of convenience of explanation, and the present invention is not limited to this.

[0174] The receiving terminal may operate the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) as a sidelink DRX timer after performing HARQ feedback in slot n+6, which is the second and last PSFCH transmission, to receive a retransmission grant. When the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) expires, if the data of the corresponding sidelink process was not successfully decoded or the HARQ feedback is a NACK, the receiving terminal may operate the sidelink DRX HARQ retransmission timer (sl-drx-HARQ-RetransmissionTimer) to expect to receive a retransmission grant through PSCCH monitoring.

[0175] Further, as an example, referring to FIG. 19(c), a designated PSFCH resource may be designated within PSSCH resource 1940. As an example, the designated PSFCH resource within PSSCH resource 1940 may be indicated via an SCI, and the designated PSFCH resource may be added as a HARQ feedback transmission opportunity. In FIG. 19(c), a terminal may receive an SCI and data via a PSCCH / PSSCH in slot n. The receiving terminal may recognize that a PSFCH occasion 1910 located in slot n+4 is associated with the PSSCH received in slot n and is a HARQ feedback transmission opportunity. Furthermore, the receiving terminal may recognize that the designated PSFCH resource within PSSCH resource 1940 indicated by the SCI is a HARQ feedback transmission opportunity. Here, the designated PSFCH resource within PSSCH resource 1940 may be located in slot n+3. That is, the designated PSFCH resource in the PSSCH resource 1940 of slot n+3 may be the first HARQ feedback transmission opportunity, and the PSFCH resource 1910 located in slot n+4 may be the second HARQ feedback transmission opportunity. Here, as an example, the receiving terminal may fail to transmit HARQ feedback due to an LBT failure in the first HARQ feedback transmission opportunity located in slot n+3, but may perform HARQ feedback transmission by successfully completing the LBT in the second HARQ feedback transmission opportunity 1910 located in slot n+4. However, this is merely an example for convenience of explanation and is not limited thereto. The receiving terminal may perform HARQ feedback in slot n+4, which is the second and last PSFCH transmission opportunity, to receive a retransmission grant, and then operate a sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) as a sidelink DRX timer.When the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) expires, if the data of the corresponding sidelink process has not been successfully decoded or the HARQ feedback is a NACK, the receiving terminal can operate the sidelink HARQ retransmission timer (sl-drx-HARQ-RetransmissionTimer) and expect to receive a retransmission grant through PSCCH monitoring.

[0176] As another example, a case where HARQ feedback is performed only through a semi-statically configured PSFCH can be considered. For example, HARQ feedback can be performed in one HARQ feedback transmission opportunity, and sidelink DRX operation can be performed based on the HARQ feedback. However, considering the MCOT limitation of SL-U, the HARQ feedback operation may be limited, and therefore improvement operations may be required.

[0177] As a specific example, FIG. 20 is a diagram illustrating a PSSCH resource designated for HARQ feedback considering a single HARQ feedback transmission opportunity applied to the present disclosure. Referring to FIG. 20, a receiving terminal may receive SCI and data through the PSCCH / PSSCH of slot n. Here, the SCI may indicate a HARQ feedback PSSCH resource 2010 as a PSFCH resource for HARQ feedback. The receiving terminal may perform HARQ feedback through the HARQ feedback PSSCH resource 2010. As an example, if multiple HARQ feedback transmission opportunities are deactivated, the receiving terminal may transmit HARQ feedback through the HARQ feedback PSSCH resource 2010 indicated by the SCI, and may not perform HARQ feedback transmission through the PSFCH resource 2020 located in slot n+4 associated with the PSSCH of slot n. The receiving terminal may operate a sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) as a timer after the indicated HARQ feedback PSSCH resource 2010. When the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) expires, if the data of the corresponding sidelink process has not been successfully decoded or the HARQ feedback is a NACK, the receiving terminal can operate the sidelink DRX HARQ retransmission timer (sl-drx-HARQ-RetransmissionTimer) and expect to receive a retransmission grant through PSCCH monitoring.

[0178] Here, as an example, as shown in Table 12 below, the transmitting terminal can receive HARQ information from the physical layer at a PSFCH reception occasion corresponding to PSSCH transmission, and if it fails to receive this information, it can transmit a NACK in the corresponding sidelink process. Also, if the transmitting terminal fails to receive HARQ feedback information at a PSFCH reception occasion, it can increment a counter (e.g., numConsecutiveDTX). Here, if the counter (e.g., numConsecutiveDTX) reaches a threshold (e.g., sl-maxNumConsecutiveDTX), a HARQ-based sidelink RLF (radio link failure) may occur. However, Table 12 is merely an example and is not limited thereto.

[0179] When a sidelink RLF occurs, the transmitting terminal (source UE) with which the PC5-RRC link is established can release the data radio bearer (DRB) and signaling radio bearer (SRB) with the receiving terminal (destination UE) and delete the sidelink configuration. The transmitting terminal can also reset the MAC and release the PC5-RRC with the receiving terminal.

[0180] [Table 12]

[0181] Sidelink RLF may be a procedure for detecting problems in channel conditions / physical layers and configured settings. For example, in an SL-U environment, HARQ feedback transmission may be impossible due to an LBT failure. Since this may be different from RLF, operation taking SL-U into consideration may be required.

[0182] As a specific example, when multiple HARQ feedback transmission opportunities are configured, the counter for RLF (numConsecutiveDTX) may be set to increment when HARQ feedback is not received in all HARQ transmission opportunities based on bundling of the multiple HARQ feedback transmission opportunities. That is, since an LBT failure is not a failure due to channel conditions, RLF may be determined based on all of the multiple HARQ feedback transmission opportunities.

[0183] Figure 21 is a diagram illustrating a HARQ feedback transmission opportunity bundling operation to which the present disclosure is applied. Referring to Figure 21, a transmitting terminal may transmit SCI and data over a PSCCH / PSSCH in slot n. Here, multiple PSFCH occasions associated with the PSCCH / PSSCH in slot n may be semi-statically configured. As an example, in Figure 21, a first PSFCH occasion 2110 and a second PSFCH occasion 2120 may be configured as multiple HARQ feedback transmission opportunities, but this is merely an example for convenience of explanation and is not limited thereto. That is, two or more HARQ feedback transmission opportunities may be configured.

[0184] Referring to FIG. 21, a transmitting terminal and a receiving terminal can bundle HARQ feedback transmission opportunities and transmit and receive HARQ feedback. The transmitting terminal can determine whether to increment a counter for RLF (numConsecutiveDTX) based on the HARQ feedback transmission opportunity bundling. As a specific example, a MAC entity of the terminal can perform a HARQ-based sidelink RLF detection procedure when a PSSCH transmission corresponding to a source layer-2 ID and destination layer-2 ID pair occurs. As an example, the terminal can configure and receive a counter for RLF (numConsecutiveDTX), a threshold for RLF (sl-maxNumConsecutiveDTX), and HARQ feedback transmission opportunity bundling information based on upper layer configuration. If the UE fails to receive HARQ feedback for each PSFCH reception occasion 2110, 2120 associated with a PSSCH transmission and the PSFCH reception occasion is the last occasion in the bundling of HARQ feedback transmission opportunities, the UE may increment the counter (numConsecutiveDTX) by 1. Conversely, if the PSFCH reception occasion is not the last occasion in the bundling of transmission opportunities, the counter (numConsecutiveDTX) may not be incremented. Further, as an example, the UE may initialize the counter (numConsecutiveDTX) to 0 if there is HARQ feedback reception in a PSFCH reception occasion associated with a PSSCH transmission. If the counter (numConsecutiveDTX) reaches a threshold (maxNumConsecutiveDTX) for RLF, the UE may indicate to higher layers that a sidelink RLF has been detected.

[0185] As a specific example, in FIG. 21 , the transmitting terminal may not increment the counter (numConsecutiveDTX) even if it does not receive HARQ feedback on the first PSFCH occasion 2110. If the terminal fails to receive HARQ feedback on the second PSFCH occasion 2120 as the last occasion, it may increment the counter (numConsecutiveDTX) by 1. On the other hand, if the transmitting terminal receives HARQ feedback on the first PSFCH occasion 2110, the transmitting terminal may not increment the counter (numConsecutiveDTX) regardless of whether it receives HARQ feedback on the second PSFCH occasion 2120. Furthermore, if the transmitting terminal fails to receive HARQ feedback on the first PSFCH occasion 2110 but receives HARQ feedback on the second PSFCH occasion 2120, the transmitting terminal may not increment the counter (numConsecutiveDTX). 21 has been described with reference to a PSFCH reception occasion, but is not limited thereto. For example, the above operation may include HARQ feedback occasions via PSSCH / PSCCH. As another example, the counter (numConsecutiveDTX) may be configured to increase when there is no HARQ feedback in a specific occasion other than the last occasion of the HARQ feedback transmission bundle, and is not limited to a specific embodiment.

[0186] FIG. 22 is a flowchart illustrating an operation of a wireless user equipment (UE) to which the present disclosure can be applied. As an example, the wireless user equipment (UE) may be the terminal described above, and is not limited to a specific form. Referring to FIG. 22, the wireless user equipment (UE) may receive configuration of at least one HARQ feedback transmission opportunity (S2210). That is, the wireless user equipment (UE) may receive configuration of multiple HARQ feedback transmission opportunities or one HARQ feedback transmission opportunity. The wireless user equipment (UE) may transmit HARQ feedback based on the configured at least one HARQ feedback transmission opportunity (S2220). The wireless user equipment (UE) may operate a sidelink DRX HARQ RTT timer based on the HARQ feedback transmission (S2230), and may receive a retransmission grant upon expiration of the sidelink DRX HARQ RTT timer (S2240). Here, the wireless user equipment (UE) may receive a retransmission grant based on the sidelink DRX HARQ retransmission timer if the sidelink DRX HARQ RTT timer expires and the data for the sidelink process is not successfully decoded or if the HARQ feedback information is a NACK. Here, for example, at least one HARQ feedback transmission opportunity may be configured based on at least one of a semi-static PSFCH configuration and a dynamic PSFCH resource indication. For example, the sidelink DRX HARQ RTT timer may be variably configured based on a HARQ feedback transmission opportunity that has been successfully transmitted among the plurality of HARQ feedback transmission opportunities. As another example, the sidelink DRX HARQ RTT timer may operate based on a specific HARQ feedback transmission opportunity among the plurality of HARQ feedback transmission opportunities. Here, the specific HARQ feedback transmission opportunity may refer to, but is not limited to, the last HARQ feedback transmission opportunity among the plurality of HARQ feedback transmission opportunities.

[0187] As another example, the at least one HARQ feedback transmission opportunity may be one HARQ feedback transmission opportunity, where the one HARQ feedback transmission opportunity may be indicated as a resource for HARQ feedback in the PSSCH, and the sidelink DRX HARQ RTT timer may operate based on the resource for HARQ feedback in the PSSCH, as described above.

[0188] FIG. 23 is a diagram showing a base station apparatus and a terminal apparatus to which the present disclosure can be applied.

[0189] The base station device 2300 may include a processor 2320 , an antenna unit 2312 , a transceiver 2314 , and a memory 2316 .

[0190] The processor 2320 performs baseband-related signal processing and may include an upper layer processing unit 2330 and a physical layer processing unit 2340. The upper layer processing unit 2330 may process operations of a medium access control (MAC) layer, a radio resource control (RRC) layer, or higher layers. The physical layer processing unit 2340 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 2320 may control the overall operation of the base station device 2300.

[0191] The antenna unit 2312 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.

[0192] The memory 2316 can store information processed by the processor 2320, software associated with the operation of the base station device 2300, an operating system, applications, etc., and can include components such as buffers.

[0193] The processor 2320 of the base station device 2300 may be configured to perform the operations of the base station in the embodiments described herein.

[0194] The terminal device 2350 may include a processor 2370, an antenna unit 2362, a transceiver 2364, and a memory 2366. As an example, in the present invention, the terminal device 2350 can communicate with the base station device 2300. As another example, in the present invention, the terminal device 2350 can perform sidelink communication with another terminal device. That is, the terminal device 2350 of the present invention refers to a device that can communicate with at least one of the base station device 2300 and another terminal device, and is not limited to communication with a specific device.

[0195] The processor 2370 performs baseband-related signal processing and may include an upper layer processing unit 2380 and a physical layer processing unit 2390. The upper layer processing unit 2380 may process operations of the MAC layer, the RRC layer, or higher layers. The physical layer processing unit 2390 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 2370 may control the overall operation of the terminal device 2350.

[0196] The antenna unit 2362 may include one or more physical antennas, and when multiple antennas are included, may support MIMO transmission and reception, and may also support beamforming.

[0197] The memory 2366 can store information processed by the processor 2370, software associated with the operation of the terminal device 2350, an operating system, applications, etc., and can include components such as buffers.

[0198] The terminal device 2350 according to an embodiment of the present invention may be associated with a vehicle. For example, the terminal device 2350 may be built into, located in, or located on the vehicle. The terminal device 2350 according to the present invention may be the vehicle itself. The terminal device 2350 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 2350 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 2350 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.

[0199] Here, vehicles to which the present invention is applicable may include autonomous vehicles, semi-autonomous vehicles, non-autonomous vehicles, etc. Meanwhile, although the terminal device 2350 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.

[0200] In addition, the terminal device 2350 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 2350 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.

[0201] Further, as an example, the terminal device 2350 may receive configuration of multiple HARQ feedback transmission opportunities or one HARQ feedback transmission opportunity. The terminal device 2350 may transmit HARQ feedback based on the configured at least one HARQ feedback transmission opportunity. The terminal device 2350 may operate a sidelink DRX HARQ RTT timer based on the HARQ feedback transmission and receive a retransmission grant when the sidelink DRX HARQ RTT timer expires. Here, the terminal device 2350 may receive a retransmission grant based on the sidelink DRX HARQ retransmission timer when the sidelink DRX HARQ RTT timer expires and data of the sidelink process is not successfully decoded or when the HARQ feedback information is a NACK. Here, as an example, the at least one HARQ feedback transmission opportunity may be configured based on at least one of a semi-static PSFCH configuration and a dynamic PSFCH resource indication. For example, the sidelink DRX HARQ RTT timer may be variably configured based on a HARQ feedback transmission opportunity that has been successfully transmitted among multiple HARQ feedback transmission opportunities. For another example, the sidelink DRX HARQ RTT timer may operate based on a specific HARQ feedback transmission opportunity among multiple HARQ feedback transmission opportunities. Here, the specific HARQ feedback transmission opportunity may refer to, but is not limited to, the last HARQ feedback transmission opportunity among the multiple HARQ feedback transmission opportunities. For another example, the at least one HARQ feedback transmission opportunity may be one HARQ feedback transmission opportunity. Here, one HARQ feedback transmission opportunity may be indicated as a resource for HARQ feedback within the PSSCH. The sidelink DRX HARQ RTT timer may operate based on a resource for HARQ feedback within the PSSCH, as described above.

[0202] 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.

[0203] 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.

[0204] 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]

[0205] The above may also be applied to other systems.

Claims

1. 1. A wireless user equipment (UE) operating in a sidelink unlicensed spectrum 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 as follows: receiving configuration of at least one hybrid automatic repeat and request (HARQ) feedback transmission opportunity; Transmitting HARQ feedback based on the configured at least one HARQ feedback transmission opportunity; activating a sidelink DRX (discontinuous reception) HARQ RTT (round trip time) timer based on the HARQ feedback transmission; The wireless user equipment receives a retransmission grant when the sidelink DRX HARQ RTT timer expires.

2. 2. The wireless user equipment (WUE) of claim 1, wherein the WUE receives the retransmission grant based on a sidelink DRX HARQ retransmission timer when the sidelink DRX HARQ RTT timer expires and data for a sidelink process is not successfully decoded or when HARQ feedback information is a NACK.

3. The wireless user equipment (10) of claim 1, wherein the at least one HARQ feedback transmission opportunity is configured in plurality based on at least one of a semi-static physical sidelink feedback channel (PSFCH) configuration and a dynamic PSFCH resource indication.

4. The wireless user equipment (UE) of claim 3 , wherein the sidelink DRX HARQ RTT timer is configured to operate based on a HARQ feedback transmission opportunity that has been successfully transmitted among the plurality of HARQ feedback transmission opportunities.

5. The wireless user equipment (UE) of claim 3 , wherein the sidelink DRX HARQ RTT timer operates based on a specific HARQ feedback transmission opportunity among the plurality of HARQ feedback transmission opportunities.

6. The wireless user equipment (10) of claim 1, wherein the at least one HARQ feedback transmission opportunity is comprised of one.

7. The wireless user equipment (UE) of claim 6 , wherein the one HARQ feedback transmission opportunity indicates a resource for HARQ feedback within a physical sidelink shared channel (PSSCH).

8. The wireless user equipment (UE) of claim 3 , wherein the sidelink DRX HARQ RTT timer operates based on resources for the HARQ feedback in the PSSCH.

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