Method and apparatus for performing sidelink communication in unlicensed band

Abstract

A wireless user equipment (UE) in a wireless communication system may be configured with at least one hybrid automatic repeat request (HARQ) feedback transmission opportunity, may transmit HARQ feedback based on the configured at least one HARQ feedback transmission opportunity, may operate a sidelink discontinuous reception (DRX) HARQ round trip time (RTT) timer based on the HARQ feedback transmission, and may transmit the HARQ feedback based on the HARQ feedback transmission opportunity. And if the sidelink DRX HARQ RTT timer expires, a retransmission grant may be received.

Description

Technical Field

[0001] The present disclosure relates to methods and apparatuses for performing sidelink communication in an unlicensed band of a wireless communication system. More specifically, the present disclosure relates to methods and apparatuses for operating a hybrid automatic repeat request (HARQ) timer in a sidelink unlicensed band (SL-U). Background Art

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

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

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

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

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

[0009] The technical subject matter of the present disclosure relates to methods and apparatuses for operating a hybrid automatic repeat request (HARQ) timer in a sidelink unlicensed band (SL-U).

[0010] The technical subject matter of the present disclosure relates to methods and apparatuses for operating a HARQ timer based on a physical sidelink feedback channel (PSFCH) transmission opportunity in SL-U.

[0011] The technical subject matter to be achieved by the present disclosure is not limited to the above technical subject matter, and other technical subject matter not described can be clearly understood by those of ordinary skill in the art to which the present disclosure pertains according to the following description.

[0012] Technical Solutions

[0013] According to one aspect of the present disclosure, there is provided a wireless user equipment (UE) operating in a sidelink unlicensed band in a wireless communication system. The wireless UE includes: at least one antenna configured to transmit and receive one or more wireless signals; at least one processor; and a memory configured to store instructions for the wireless UE when executed by the at least one processor, wherein the wireless UE is configured to have at least one hybrid automatic repeat 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 if the sidelink DRX HARQ RTT timer expires.

[0014] According to one aspect of the present disclosure, if the sidelink DRX HARQ RTT timer expires and the data of the sidelink process is not successfully decoded, or the HARQ feedback information is NACK, the wireless UE may be configured to receive the retransmission grant based on a sidelink DRX HARQ retransmission timer.

[0015] According to one aspect of the present disclosure, the at least one HARQ feedback transmission opportunity may be configured as multiple based on at least one of a semi-static physical sidelink feedback channel (PSFCH) configuration and a dynamic PSFCH resource indication.

[0016] According to one aspect of the present disclosure, the sidelink DRX HARQ RTT timer may be operated based on a HARQ feedback transmission opportunity in which the HARQ feedback transmission in the multiple HARQ feedback transmission opportunities is successful.

[0017] According to one aspect of the present disclosure, the sidelink DRX HARQ RTT timer may operate based on a specific HARQ feedback transmission opportunity among the plurality of HARQ feedback transmission opportunities.

[0018] According to one aspect of the present disclosure, the at least one HARQ feedback transmission opportunity may be configured as one.

[0019] According to one aspect of the present disclosure, the one HARQ feedback transmission opportunity may be indicated as a resource for HARQ feedback within a Physical Sidelink Shared Channel (PSSCH).

[0020] According to one aspect of the present disclosure, the sidelink DRX HARQ RTT timer may operate based on the resource for the HARQ feedback within the PSSCH.

[0021] Technical Effects

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

[0023] According to the present disclosure, a method for operating a Hybrid Automatic Repeat reQuest (HARQ) timer in a sidelink unlicensed band (SL-U) may be provided.

[0024] According to the present disclosure, a method for operating a HARQ timer based on a Physical Sidelink Feedback Channel (PSFCH) transmission opportunity in SL-U may be provided.

[0025] The effects that can be achieved by the present disclosure are not limited to the above effects, and other effects not described can be clearly understood by those of ordinary skill in the art to which the present disclosure pertains based on the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 An example of a New Radio (NR) frame structure to which the present disclosure can be applied is shown.

[0028] Figure 2 An NR resource structure to which the present disclosure can be applied is shown.

[0029] Figure 3 An NR sidelink time slot structure to which the present disclosure can be applied is shown.

[0030] Figure 4 An NR sidelink frequency to which the present disclosure can be applied is shown.

[0031] Figure 5 An NR sidelink resource pool configuration to which the present disclosure can be applied is shown.

[0032] Figure 6 Shows the unlicensed bands for each area for NR side - link communication to which the present disclosure can be applied.

[0033] Figure 7 Shows the use of the 5 gigahertz (GHz) unlicensed band to which the present disclosure can be applied.

[0034] Figure 8 Shows a method for increasing the bandwidth considering the power spectral density (PSD) limit to which the present disclosure can be applied.

[0035] Figure 9 Shows a method for configuring a guard band considering the shared frequency band within a cell to which the present disclosure can be applied.

[0036] Figure 10 Shows the unlicensed bands applicable to the present disclosure.

[0037] Figure 11 Shows the side - link resource pool to which the present disclosure can be applied.

[0038] Figure 12 Shows the side - link discontinuous reception (DRX) hybrid automatic repeat request (HARQ) round - trip time (RTT) timer to which the present disclosure can be applied.

[0039] Figure 13 Shows a method for the side - link timer in the operation resource pool to which the present disclosure can be applied, where a physical side - link feedback channel (PSFCH) is not configured in the resource pool.

[0040] Figure 14 Shows the side - link HARQ feedback operation to which the present disclosure can be applied.

[0041] Figure 15 Shows the PSSCH - PSFCH mapping for HARQ feedback transmission to which the present disclosure can be applied.

[0042] Figure 16 Shows the channel occupancy time (COT) structure to which the present disclosure can be applied.

[0043] Figure 17 Shows a method for configuring multiple PSFCH transmission opportunities to which the present disclosure can be applied and a method for configuring the side - link DRX timer based on this.

[0044] Figure 18 Shows a method for configuring multiple HARQ feedback transmission opportunities through semi - static PSFCH configuration to which the present disclosure can be applied and for performing side - link DRX timer operation based on this.

[0045] Figure 19 Disclosed is a method of configuring multiple HARQ feedback transmission opportunities by using semi-statically configured PSFCH timing and dedicated PSFCH resources to which the present disclosure can be applied, and operating a sidelink DRX timer based thereon.

[0046] Figure 20 Disclosed is dedicated PSSCH resources for HARQ feedback considering a single HARQ feedback transmission opportunity to which the present disclosure can be applied.

[0047] Figure 21 Disclosed is a HARQ feedback transmission opportunity bundling operation to which the present disclosure can be applied.

[0048] Figure 22 is a flowchart showing operations of a wireless UE to which the present disclosure can be applied.

[0049] Figure 23 is a diagram showing a base station device and a terminal device to which the present disclosure can be applied. Detailed Description

[0050] Various examples of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, so that those of ordinary skill in the art to which the present disclosure pertains can easily implement these examples. However, the present disclosure can be implemented in various forms and is not limited to the examples described herein.

[0051] When describing the examples of the present disclosure, detailed descriptions of known configurations or functions may be omitted for clarity and conciseness. Throughout the drawings and the detailed description, unless otherwise stated, the same reference numerals are understood to represent the same elements, features, and structures.

[0052] It will be understood that when an element is referred to as being "connected to", "coupled to", or "accessed" another element, it can be directly connected, coupled, or accessed to the other element, or there may be intervening elements. Further, it will be understood that when an element is described as "including / containing" or "having" another element, it specifies the presence of the other element, but does not exclude the presence of another element described in other ways.

[0053] In addition, terms such as first, second, etc. may be used herein to describe elements in the description herein. These terms are used to distinguish one element from another. Therefore, the terms do not limit the elements, the order of arrangement, or the sequence, etc. Thus, a first element in one example may be referred to as a second element in another example. Similarly, a second element in one example may be referred to as a first element in another example.

[0054] Here, providing the distinguishing elements is merely for clearly explaining each feature, and does not mean that the elements must be separated from each other. That is, multiple elements can be integrated into a single hardware or software unit. Moreover, a single element can be distributed into multiple hardware or software units. Therefore, unless otherwise specifically described, the integrated or distributed examples are also included within the scope of the present disclosure.

[0055] Here, the elements described in the various examples may not be necessary and can be partially optional. Therefore, examples including a partial set of the elements described in the examples are also included within the scope of the present disclosure. In addition, examples further including another element in addition to the elements described in the various examples are also included within the scope of the present disclosure.

[0056] The descriptions herein relate to a wireless communication network, and the operations performed in the wireless communication network can be performed in the process of a system (such as a base station) that controls the wireless network to control the network and transmit data, or can be performed in a user equipment.

[0057] Obviously, in a network including a base station and multiple network nodes, various operations performed for communicating with a UE can be performed by the base station or other network nodes other than the base station. Here, the term "base station (BS)" can be used interchangeably with other terms, such as a fixed station, Node B, eNodeB (eNB), gNodeB (gNB), and access point (AP). In addition, the term "terminal" can be used interchangeably with other terms, such as user equipment (UE), mobile station (MS), mobile subscriber station (MSS), subscriber station (SS), and non-AP station (non-AP STA).

[0058] Here, transmitting or receiving a channel includes the meaning of transmitting or receiving information or a signal through the corresponding channel. For example, transmitting a control channel means transmitting control information or a signal through the control channel. Similarly, transmitting a data channel means transmitting data information or a signal through the data channel.

[0059] In the following description, although the term "New Radio (NR) system" is used to distinguish the systems according to the various examples of the present disclosure from existing systems, the scope of the present disclosure is not limited thereto.

[0060] The New Radio (NR) system supports various subcarrier spacings (SCSs) by considering various scenarios, service requirements, potential system compatibilities, etc. In addition, to overcome the adverse channel environments such as high path loss, phase noise, and frequency offset that occur at high carrier frequencies, the NR system can support the transmission of physical signals / channels through multiple beams. In this way, the NR system can support a variety of applications, such as enhanced mobile broadband (eMBB), massive machine type communication (mMTC) / ultra-massive machine type communication (uMTC), and ultra-reliable and low-latency communication (URLLC).

[0061] Here, 5G mobile communication technology can be defined by including the existing Advanced Long Term Evolution (LTE-A) system and the above-mentioned NR system. That is to say, 5G mobile communication technology can operate by considering backward compatibility with previous systems and the newly defined NR system. Therefore, subsequent 5G mobile communication can include technologies operating based on the NR system and technologies operating based on previous systems (e.g., LTE-A, LTE), but is not limited to specific systems.

[0062] First, the physical resource structure of the NR system to which the present disclosure is applied will be briefly described.

[0063] Figure 1 An example of an NR frame structure according to an example of the present invention is shown.

[0064] In NR, the basic unit in the time domain can be T c = 1 / (Δf max ·N f ). Here, Δf max = 480·10 3 and N f = 4096. In addition, k = T s / T c = 64 can be a constant regarding the multiple relationship between the NR time unit and the LTE time unit. In LTE, T s = 1 / (Δf ref ·N f,ref ), Δf ref = 15·10 3 and N f,ref = 2048 can be defined as the reference time unit. The constant regarding the multiple relationship between the NR time basic unit and the LTE time basic unit can be defined as k = T s / T c = 64.

[0065] Referring to Figure 1 , the time structure of the frame for downlink / uplink (DL / UL) transmission can include T f = (Δfmax N f / 100)·T s = 10 ms. Here, a single frame may include corresponding to T sf = (Δf max N f / 1000)·T s = 1 ms of 10 sub - frames. The number of consecutive Orthogonal Frequency Division Multiplexing (OFDM) symbols per sub - frame may be In addition, each frame may be divided into two half - frames, and a half - frame may include sub - frames 0 to 4 and sub - frames 5 to 9. Here, half - frame 1 may include sub - frames 0 to 4, and half - frame 2 may include sub - frames 5 to 9.

[0066] N TA represents the Timing Advance (TA) between the Downlink (DL) and the Uplink (UL). Here, according to Equation 1 below, the transmission timing of uplink transmission frame i is determined based on the downlink reception timing at the UE.

[0067] [Equation 1]

[0068] T TA = (N TA + N TA,offset )T c

[0069] N TA,offset represents the TA offset value that appears due to duplex mode differences, etc. Basically, in Frequency Division Duplexing (FDD), N TA,offset = 0. In Time Division Duplexing (TDD), N can be defined as a fixed value by considering the margin of the DL - UL switching time. For example, in TDD (Time Division Duplexing) of RF1 (Frequency Range 1) (which is a frequency below 6 GHz or lower), N TA,offset can be 39936T TA,offset or 2600T C . 39936T C = 20.327 μs and 25600T C = 13.030 μs. In addition, in FR2 (Frequency Range 2) for millimeter - wave (mmWave), N C can be 13792T TA,offset . At this time, 39936T C = 7.020 μs. C

[0070] Figure 2 shows the NR resource structure to which the present disclosure can be applied.

[0071] Resource elements within a resource grid can be indexed based on each subcarrier spacing. Here, a single resource grid can be generated for each antenna port and each subcarrier spacing. Uplink / downlink transmission and reception can be performed based on the corresponding resource grid.

[0072] A resource block (RB) in the frequency domain is configured with 12 resource elements (REs), and for every 12 REs, an index (n PRB ) of an RB can be configured. The index of the RB can be used within a specific frequency band or system bandwidth. The index of the RB can be defined as shown in Equation 2 below. Here, N RB sc represents the number of subcarriers of each RB, and k represents the subcarrier index.

[0073] [Equation 2]

[0074]

[0076] Digital parameter configurations can be configured differently to meet the various services and requirements of the NR system. For example, one subcarrier spacing (SCS) can be supported in the LTE / LTE-A system, but multiple SCSs can also be supported in the NR system.

[0077] The new digital parameter configurations of the NR system supporting multiple SCSs can operate in frequency ranges or carriers such as 3 GHz or less, 3 GHz - 6 GHz, 6 GHz - 52.6 GHz or greater to address the problem that wide bandwidth cannot be obtained in frequency ranges or carriers such as 700 MHz or 2 GHz.

[0078] Table 1 below shows an example of the digital parameters supported by the NR system.

[0079] [Table 1]

[0080] μ <![CDATA[Δf = 2 μ ·15 [kHz]]]> Cyclic Prefix 0 15 Normal 1 30 Normal 2 60 Normal, Extended 3 120 Normal 4 240 Normal

[0081] Referring to Table 1 above, the digital parameter configuration can be defined based on the SCS, cyclic prefix (CP) length, and the number of OFDM symbols per time slot used in the OFDM system. The above values can be provided to the UE through the higher layer parameters DL-BWP-mu and DL-BWP-cp for the downlink, and through the higher layer parameters UL-BWP-mu and UL-BWP-cp for the uplink.

[0082] In Table 1 above, if μ = 2 and SCS = 60 kHz, then normal CP and extended CP can be applied. In other frequency bands, only normal CP can be applied.

[0083] Here, a normal time slot can be defined as the basic time unit for transmitting a single piece of data and control information in the NR system. The length of a normal time slot can basically include 14 OFDM symbols. In addition, different from a time slot, a subframe can have an absolute time length corresponding to 1 ms in the NR system and can be used as a reference time for the length of another time segment. Here, for the coexistence and backward compatibility of LTE and NR systems, the NR standard may require a time segment such as an LTE subframe.

[0084] For example, in LTE, data can be transmitted based on a transmission time interval (TTI) as the unit time. The TTI can include at least one subframe unit. Here, even in LTE, a single subframe can be set to 1 ms and can include 14 OFDM symbols (or 12 OFDM symbols).

[0085] In addition, in the NR system, a non-slot can be defined. A non-slot can refer to a time slot having a number of symbols that is at least one symbol less than the number of symbols in a normal time slot. For example, in the case of providing low latency such as ultra-reliable and low-latency communication (URLLC) services, the latency can be reduced by a non-slot having a number of time slots less than that of a normal time slot. Here, the number of OFDM symbols included in a non-slot can be determined based on the frequency range. For example, a non-slot having a length of 1 OFDM symbol can be considered in a frequency range of 6 GHz or higher. As another example, the number of symbols used to define a non-slot can include at least two OFDM symbols. Here, the number range of OFDM symbols included in a non-slot can be configured to have a mini-slot length up to (normal time slot length) - 1. Here, although the number of OFDM symbols can be limited to 2, 4, or 7 as a non-slot standard, it is provided only as an example.

[0086] In addition, for example, the SCS corresponding to μ = 1 and 2 can be used in an unlicensed band of 6 GHz or less, and the SCS corresponding to μ = 3 and 4 can be used in an unlicensed band of 6 GHz or more. Here, for example, if μ = 4, it can be used for a synchronization signal block (SSB).

[0087] [Table 2]

[0088]

[0089] Table 2 shows the number of OFDM symbols for each time slot with normal CP set by the subcarrier spacing The number of time slots per frame and the number of time slots per subframe In Table 2, these values are based on a normal time slot having 14 OFDM symbols.

[0090] [Table 3]

[0091]

[0092] In Table 3, in the case of applying an extended CP (i.e., μ = 2 and SCS = 60 kHz), the number of time slots per frame and the number of time slots per subframe of a normal time slot having 12 OFDM symbols per time slot are shown.

[0093] As described above, a single subframe may correspond to 1 ms on the time axis. Moreover, a single time slot may correspond to 14 symbols on the time axis. For example, a single time slot may correspond to 7 symbols on the time axis. Thus, the number of time slots and the number of symbols that can be considered can be set differently within 10 ms corresponding to a single radio frame. Table 4 can show the number of time slots and the number of symbols according to each SCS. Although the SCS of 480 kHz may not be considered in Table 4, the present disclosure is not limited to such an example.

[0094] [Table 4]

[0095] SCS Time Slots within 10 ms Time Slots within 10 ms Symbols within 10 ms 15 kHz 10 20 140 30 kHz 20 40 280 60 kHz 40 80 560 120 kHz 80 N / A 1120 240 kHz 160 N / A 2240 480 kHz 320 N / A 4480

[0097] The V2X service may support a set of basic requirements for the V2X service. These requirements are basically designed with full consideration of road safety services. Here, the V2X UE may exchange autonomous state information through SL. The V2X UE may also exchange information with infrastructure nodes and / or pedestrians.

[0098] The V2X service (e.g., LTE Rel-15) may support at least one of the following: carrier aggregation in SL, higher-order modulation, latency reduction, transmit (Tx) diversity, and sTTI (transmission time interval). To this end, new features may be applied to V2X communication. More specifically, the V2X UE may operate considering coexistence with other V2X UEs. For example, the V2X UE may use the same resource pool as other V2X UEs.

[0099] For example, by considering the usage scenarios for supporting V2X services as System Aspect (SA) 1, the technical features can be classified mainly based on the four categories shown in Table 5 below, but are not limited thereto. In Table 5, "vehicle platooning" can be a technology that enables multiple vehicles to dynamically form a group and operate similarly. "Extended sensors" can be a technology that enables the exchange of data collected from sensors or video images. "Advanced driving" can be a technology that enables a vehicle to be based on semi-automated or fully automated driving. "Remote driving" can be a technology for remotely controlling a vehicle and a technology for providing applications. Based on this, further descriptions related thereto are given in Table 5 below.

[0100] [Table 5]

[0101]

[0102] In addition, SA1 can support operation in various systems (such as LTE and NR) because enhanced V2X (eV2X) supports the technologies for supporting the V2X services. For example, the NR V2X system can be the first V2X system. In addition, the LTE V2X system can be the second V2X system. That is to say, the NR V2X system and the LTE V2X system can be different V2X systems.

[0103] The method for meeting the required low latency and high reliability in NR SL based on the NR V2X system is described below. However, the same or similar components can be extended and applied to the LTE V2X system, and include but are not limited to the following examples. That is to say, in the LTE V2X system, the present disclosure can be applied to the interactive part.

[0104] Here, the NR V2X capabilities can be not limited to basically only supporting V2X services, and the V2X RAT to be used can be selected.

[0105] In addition, new service requirements for the public safety and commercial usage scenarios of the NR V2X service can be further considered. For example, the usage scenarios can include but are not limited to at least one of the following: more advanced V2X services, public safety services, network control interactive services (NCIS), railway clearance analysis (MONASTERYEND), energy-efficient and wide-coverage enhanced relay (REFEC), and audiovisual service production (AVPROD) certification.

[0106] Physical channels, signals, basic time slot structures, and physical resources can be configured for NR V2X. Here, the NR physical SL shared channel (NR PSSCH) can be a physical layer NR SL data channel. V2X UEs can exchange data and control information (e.g., the second SCI, CSI) through the NR PSSCH. The NR physical SL control channel (NR PSCCH) can be a physical layer NR SL control channel. The NR PSCCH is a channel for transmitting scheduling information of the NR SL data channel and control information (the first SL control information (SCI)) including the second SCI indication. That is, a V2X UE can send control information for SL data communication to another V2X UE through the PSCCH. The NR physical SL feedback channel (NR PSFCH) is a channel for transmitting physical layer NR hybrid automatic repeat request (HARQ) feedback information and HARQ-ACK feedback information corresponding to the NR SL data channel (i.e., the PSSCH). A V2X UE can send data to another V2X UE and then receive HARQ feedback information of the corresponding data through the NR PSFCH. The NR SL synchronization signal / physical SL broadcast channel (SLSS / PSBCH) block is a channel block that transmits the NR SL synchronization signal and the broadcast channel in a single continuous time. Here, the SLSS / PSBCH block can be periodically transmitted based on a set of one or more block indices to support beam-based transmission in the NR band. The synchronization signal includes a primary SL synchronization signal (PSSS) and a secondary SL synchronization signal (SSSS). The synchronization signal is generated based on at least one SLSSID value. The NR physical SL broadcast channel (PSBCH) is a channel for transmitting system information required for performing V2X SL communication. The NR PSBCH is transmitted together with the SLSS and is periodically transmitted based on a set of SLS / PSBCH block indices to support beam-based transmission.

[0107] In addition, the PSCCH and PSSCH can be defined to support NR V2X. A UE can send an SCI to another UE via the PSCCH. Here, the Tx UE can send a first SCI (the 1st SCI, SCI format 1-A) to the Rx UE via the PSCCH. The 1st SCI can be used to schedule the PSSCH and the secondary SCI (the 2nd SCI) within the PSSCH, and the 1st SCI can include priority information, time / frequency resource allocation information, resource reservation information, demodulation reference signal (DMRS) pattern information, 2nd SCI format indicator information, 2nd beta-offset indicator information as a parameter for the SCI and PSSCH rate matching operation, DMRS port count information, modulation and coding scheme (MCS) information, additional MCS table indicator information (e.g., indicating one of 64QAM, or 256QAM or the URMCS LLC table), PSFCH overhead indicator information (a parameter for the PSSCH rate matching operation for the 2nd SCI), and at least one reserved bit.

[0108] Figure 3 Fig. shows the NR SL time slot structure to which the present disclosure can be applied.

[0109] Reference Figure 3 , a single SL time slot (SL time slot) includes a single automatic gain control (AGC) symbol. Moreover, a single SL time slot includes a single Tx-Rx switching symbol. In a single SL time slot, the PSSCH is the channel through which data is sent, and it is sent through at least one sub-channel (e.g., Figure 3 two sub-channels in). In addition, in the time domain, the PSCCH (the 1st SCI), the 2nd SCI, the PSSCH (data), and the demodulation RS (DMRS) for demodulation can be sent to the remaining OFDM symbols except for the AGC symbol and the Tx-Rx switching symbol. Specifically, the positions of the PSCCH (the 1st SCI), the 2nd SCI, the PSSCH (data), and the DMRS for demodulation can be the same as those in Figure 3 , but are not limited thereto. For example, in Figure 3 , the PSCCH and the 2nd SCI are present in the first sub-channel, and in consideration of this, the PSSCH and the DMRS can be allocated. As another example, the second sub-channel refers to the sub-channel in which the PSCCH and the 2nd SCI do not exist, and the PSSCH and the DMRS can be allocated as in Figure 3 .

[0110] Here, the number of PSSCH DMRSs can be configured according to higher layer configuration, and one or more PSSCH DMRSs can be configured according to the UE's channel environment. PSCCH (the first SCI) uses the DMRS of PSCCH (i.e., PSCCH DMRS) to receive demodulation, and is evenly allocated and transmitted every four resource elements (REs) within a single resource block (RB). In contrast, PSSCH DMRS is used to decode the second SCI.

[0111] In addition, for example, a single resource pool associated with NR SL can support frequency division multiplexing (FDM), time division multiplexing (TDM), and space division multiplexing (SDM). This means that each resource in the single resource pool can be divided and used based on frequency, time, and space, which can improve resource efficiency.

[0112] Figure 4 Shows the NR SL frequencies to which the present disclosure can be applied. For example, NR SL can operate based on at least one of the following: frequency range 1 (FR1) (below 6 GHz) and frequency range 2 (FR2) (i.e., up to 52.6 GHz), unlicensed ITS band, and licensed band. Specifically, for example, referring to Figure 4 , 5,855 to 5,925 MHz can be allocated for ITS services (technology-neutral manner).

[0113] In addition, NR V2X service quality (QoS) requirements can be considered. That is, latency, reliability, and data rate may need to be satisfied through predetermined conditions related to the requirements of NR V2X services. Here, these requirements can be configured as shown in Table 6 below, and Table 7 can show the PC5 QoS for NR V2X.

[0114] Here, in order to meet the QoS requirements, access stratum (AS)-level QoS management may be required. For this purpose, HARQ and CSI feedback associated with link adaptation may be required. In addition, each of the NR V2X UEs may have a different maximum bandwidth capability (maximum BW capability). Considering this, AS-level information can be exchanged between NR V2X UEs, and the AS-level information includes at least one of the following: UE capability, QoS-related information, radio bearer configuration, and physical layer configuration.

[0115] [Table 6]

[0116]

[0117] [Table 7]

[0118] · Note 1: For the standardized PQI to QoS characteristic mapping, this table can be extended / updated to support the service requirements of other identified V2X services. · Note 2: PQI can be used for other services besides V2X.

[0120] In the following, the SL HARQ process is described. Whether the V2X UE is to report HARQ feedback is configured by a higher layer (e.g., RRC) and indicated by SCI signaling (e.g., the second SCI). For example, if the V2X UE performs SL communication based on multicast, whether to report HARQ feedback can be determined based on the distance between the Tx UE and the Rx UE.

[0121] When the V2X UE performs at least one of unicast and multicast transmissions, SL HARQ feedback can be enabled or disabled. Here, whether to enable / disable HARQ feedback can be determined based on at least one of the channel condition (e.g., RSRP), the distance between the Tx UE and the Rx UE, and the QoS requirement.

[0122] In the case of multicast, whether to send HARQ feedback can be determined based on the physical distance between the Tx UE and the Rx UE. Here, when performing HARQ feedback for multicast transmission via the PSSCH, the Rx UE can send a negative response only when the received PSSCH decoding fails. It can be referred to as Option 1 operation. In addition, when performing HARQ feedback for multicast transmission via the PSSCH, the Rx UE can feedback an affirmative response or a negative response based on whether the PSSCH decoding is successful, and this can be referred to as Option 2 operation. In Option 1 operation where only a negative response is fed back as the only NACK HARQ feedback, if the physical distance between the Tx UE and the Rx UE is less than or equal to the communication range requirement, HARQ feedback corresponding to the PSSCH reception can be performed. On the contrary, if the physical distance between the Tx UE and the Rx UE is greater than the communication range requirement, the V2X UE may not perform HARQ feedback corresponding to the PSSCH reception.

[0123] Here, the position of the Tx UE is indicated to the Rx UE through the SCI signaling associated with the PSSCH. The Rx UE can estimate the distance to the Tx UE based on both the information segment included in the received SCI and its position information, and can operate as described above.

[0124] In addition, when performing unicast communication based on V2X, the case of enabling SL HARQ feedback can be considered. The Rx UE can generate and send HARQ ACK / NACK corresponding to the PSSCH according to whether the decoding of the corresponding transport block (TB) is successful.

[0125] Then, the NR SL resource allocation mode refers to the mode in which the base station schedules SL transmission resources. Here, the mode in which the base station schedules SL transmission resources can be Mode 1. For example, when the V2X UE is within the coverage area of the base station, the V2X UE can receive SL resource information from the base station. On the contrary, there is a mode in which the V2X UE directly determines the resources for SL transmission on the SL resources configured by the base station / network or pre-configured SL resources. Here, the mode in which the UE directly determines the SL transmission resources can be Mode 2.

[0126] In addition, digital parameter configuration and waveforms for the sidelink can be considered, which can be as shown in Table 8 below. Specifically, regarding PSSCH / PSCCH and PSFCH in the sidelink, the SCS and CP lengths supported in each of FR1 and FR2 can be as shown in Table 8 below. Here, the waveform can support only OFDM and not DFT-S-OFDM, but it is not limited thereto. A sidelink synchronization signal block (SL-SSB) can be defined independently for each frequency range, which can be similar to NR-Uu.

[0127] [Table 8]

[0128]

[0130] Figure 5 Illustrates the NR sidelink (SL) resource pool configuration. Refer to Figure 5 , the resource pool can represent the resources in time and frequency for sidelink transmission and reception. For example, at least one resource pool can be configured within a single SLBWP within a single carrier. Here, the resources of the resource pool can be configured based on the time resources of the time slot set unit and the frequency resources of the continuous subchannel set unit. In addition, the resource pool can be configured for each of transmission and reception.

[0131] More specifically, as the time resources provided for resource pool configuration in the NR sidelink, at least one of the following can be configured: resource pool period, sidelink time slot set (sl-TimeResource (length = L) within a single resource pool application period bitmap), and the first symbol and the number of consecutive symbols in a consecutive symbol set within a single time slot. As frequency resources, at least one of the following can be configured: the bandwidth of at least one subchannel (e.g., sl-SubchannelSize = {10, 15, 20, 25, 50, 75, and 100} RBs), the entire bandwidth of the resource pool indicated by the number of consecutive subchannels (a set of consecutive subchannels (e.g., sl-NumSubchannel = {1 to 27})), and the position of the first subchannel of the resource pool in the frequency domain (sl-StartRBsubChannel = {0 to 265}). For example, the resources in the time domain and the frequency domain can be configured based on higher layer parameters. In Figure 5 If the total available RB resources do not exactly match the subchannel size (i.e., if it does not reach the number of RBs that make up a single subchannel), the frequency resources corresponding to the excluded resource blocks (RBs) can represent some remaining RBs. Here, the corresponding resources may not be used in the NR sidelink. In addition, for example, if the length of the bitmap in time resources (e.g., sl-TimeResource) is not established and cannot be used as an NR sidelink resource, the reserved time slots can indicate the remaining time slots.

[0132] Next, the case where an unlicensed band (unlicensed spectrum) is used for communication between the base station and the UE can be considered. For example, the communication scheme based on the unlicensed band can be a scheme of occupying a channel through competition and performing communication based on the occupied channel. Even for communication between the base station and the UE, communication based on the unlicensed band can be performed. Below, the operations in the case where the unlicensed band is used for sidelink communication are described. That is, even for sidelink communication as communication between UEs, the unlicensed band can be used. In addition, it is necessary to consider configuring the sidelink resource pool using the sidelink unlicensed band. More specifically, sidelink communication can be performed based on the resource pool. In the case of performing communication through the unlicensed band, the resource pool configuration needs to be configured differently.

[0133] For example, the sidelink communication resource pool can be configured based on time slot units, and the symbols for the sidelink within a single time slot can be determined, which is the same as Figure 5 shown. In addition, as described above in connection with Figure 5 In the frequency domain, it can be configured based on the number of consecutive subchannels. The above sidelink resource pool configuration can be configured considering unlicensed band communication, which will be described below.

[0134] Figure 6The unlicensed bands for each area of NR side - link communication to which the present disclosure can be applied are shown. In Table 8 above, the frequency range of NR FR1 can be from 450 MHz to 6 GHz, but the corresponding frequency range can vary from 450 MHz to 7.125 GHz. The frequency range of NR FR1 can be changed for the unlicensed bands of the 6 GHz band, but is not limited thereto.

[0135] For example, the unlicensed bands can be located below 1 GHz, 2.4 GHz, 5 GHz, 6 GHz, 37 GHz (only in the United States), and 60 GHz, but are not limited thereto. Here, referring to Figure 6 , for example, in a system, the 5 GHz band can be Band 46 defined as 5150 to 5925 MHz. In addition, for example, for LAA operation, Band 49 (3550 - 3700 MHz) can be defined as the Citizen Broadband Radio Service (CBRS), but is not limited thereto.

[0136] Figure 7 The use of the 5 GHz unlicensed band to which the present disclosure can be applied is shown. Referring to Figure 7 , each band within the 5 GHz unlicensed band can be set, and based on this, the use of the unlicensed band can be set. For example, it can be divided into 20 MHz units, and each 20 MHz can be a single channel.

[0137] Here, in most areas, the low - frequency band from 5150 to 5350 MHz within the above - mentioned band is specified to have a maximum transmit power of 23 dBm for indoor use. Moreover, in the band of 5470 MHz or higher, it is used in areas with a transmit power up to 30 dBm and is used outdoors in most areas. Here, for example, there may be additional requirements in some areas, given as the Effective Isotropic Radiated Power (EIRP) value based on Table 9 below, and the maximum transmit power is restricted.

[0138] [Table 9]

[0139]

[0141] Here, the Power Spectral Density (PSD) can indicate that the device is limited to perform full - power transmission within the reference bandwidth. As a detailed example, European regulations may limit the PSD to 10 dBm / MHz. Therefore, in a non - 20 MHz bandwidth, the device may not perform transmission at the maximum transmit power of 23 dBm.

[0142] Figure 8 The method of increasing the bandwidth considering the PSD limit to which the present disclosure can be applied is shown. For example, as Figure 8As shown, it is possible to consider the case of small data transmission that only requires a small bandwidth. Here, in the case of performing small data transmission through a wide bandwidth, the coverage range can be extended. In addition, the minimum bandwidth occupancy control can be satisfied by means of transmission using a wide bandwidth. Considering this, for small data, a method of performing transmission in a wide bandwidth may be preferred.

[0143] In addition, for example, in the case of occupying a channel through a channel access procedure in an unlicensed band, the maximum channel occupancy time (COT) corresponding to the maximum allowable occupancy time can be set differently for each region. For example, Japan allows a maximum COT of up to 4 ms, while Europe allows a maximum COT of up to 8 ms or 10 ms. However, this is merely an example and is not limited to the above embodiments. In addition, for example, Europe can support frame-based equipment (FBE) and load-based equipment (LBE) rules. Here, FBE can be set to high-performance radio (LAN HiperLAN) / 2, and LBE can be adopted and applied according to the Wi-Fi standard specification, and both can be supported in NR, which is a new communication system.

[0144] In addition, for example, the minimum occupancy bandwidth can be the bandwidth control that needs to be minimally occupied when a channel access is successful once. For example, the minimum occupancy bandwidth control can be configured to occupy 80% to 90% or more of the nominal channel BW. As a detailed example, when a UE sends a PUSCH to a base station in an unlicensed band, it can request resources for the PUSCH to be allocated in an interleaved form in a specific bandwidth, but it is not limited to the corresponding embodiments.

[0145] In addition, the control regarding dynamic frequency selection can be a control that restricts bandwidth use for the purpose of protecting a system (such as a radio) with a high priority for using an unlicensed band. In addition, the transmit power control regulation can be a regulation that limits the transmit power to be much lower than the maximum transmit power value allowed for use. In addition, the listen-before-talk (LBT) control can be a control of the channel access procedure, and Europe can support FBE and LBE rules. Here, FBE can be Hiperlan / 2, and LBE can be adopted and applied from the Wi-Fi standard specification, and both can be supported in NR.

[0146] In addition, for example, based on the above description, the 5 GHz unlicensed band can be used, but the use of the 6 GHz band is being discussed in each country and organization. Here, the 6 GHz band can be a band that is different from the 5 GHz band and is not used in mobile systems. That is, different from the 5 GHz band shared by multiple mobile communication systems, the 6 GHz band can be used for a single specified communication system. Therefore, problems or inefficiencies caused by the coexistence of different systems can be reduced.

[0147] Figure 9 Shows a method for configuring guard bands in consideration of a shared frequency band (e.g., an unlicensed frequency band) within a cell to which the present disclosure can be applied.

[0148] Referring to Figure 9 , to support wideband operations in shared spectrum access, a UE can receive an IntraCellGuardBandsPerSCS parameter for each of the UL carrier and the DL carrier from a base station based on the base station configuration. N RB-set,x -1 intra-cell guard bands can be provided for the UE in a single carrier (subcarrier spacing index = μ). Referring to Figure 9 , the UE can receive higher layer signaling for: the number of common resource blocks (CRBs) and the starting CRB for each guard band. For example, a CRB can be a resource block defined / configured based on Point A, which is the starting position of the transmission bandwidth in a carrier in the frequency domain. The UE can verify information about Point A through base station signaling, and based on this, can identify the CRB position in the frequency. Here, each guard band can be defined as the starting CRB based on parameters, and within each guard band, the size of the number of CRBs can be defined based on parameters. The UE can receive the aforementioned information through higher layer signaling based on each of the startCRB and nrofCRB parameters. Here, s ∈ {0, 1,..., N RB-set,x -2}, N RB-set,x represents the number of RB sets, and x can be configured for DL or UL for downlink and uplink. N RB-set,x RB sets can be configured as a resource block set (RBS) within a single carrier through guard band configuration. For example, the guard band can be configured based on the IntraCellGuardBandsPerSCS parameter, and the RBS can be configured within a single carrier accordingly.

[0149] Here, the frequency bandwidth of each RBS can correspond to an LBT frequency bandwidth. That is, each RBS can be set to a bandwidth corresponding to the LBT process performed by the base station and the UE. For example, in Figure 9In the case where LBT is successful in the corresponding region corresponding to the LBT bandwidth, RB set 1 911 and RB set 2 912 may occupy the corresponding frequency band and may perform communication. That is to say, the RBS may correspond to the LBT bandwidth. For example, a Tx node (e.g., gNB or UE) may determine the channel occupancy of the unlicensed frequency band through an LBT channel access procedure performed on the RBS resources corresponding to the LTE bandwidth. When the LBT process is successful in a single RBS, the Tx node may perform transmission on the resources corresponding to that RBS.

[0150] Here, each RBS may be defined as a starting CRB and an ending CRB. The starting CRB may be The ending CRB may be Here, the size of the guard band 913 may be nrofCRB. For example, according to the subcarrier spacing μ and the carrier size It may not be desirable to set the size nrofCRB of the guard band 913 to be less than the size of the applicable intra-cell guard band number defined considering the interference state regarding the radio bandwidth.

[0151] Here, the starting CRB and the ending CRB of each RBS (911, 912) may be determined based on the RBS index, and the RBS index may be s ∈ {0, 1, …, N RB-set,x -1}. That is to say, the RBS index s may be a resource block having size, and represents the number of CRBs determined by the starting CRB and the ending CRB based on Equation 3 below. Moreover, in each RBS, the starting CRB and the ending CRB may be as shown in Equation 4 and Equation 5 below.

[0152] [Equation 3]

[0153]

[0154] [Equation 4]

[0155]

[0156] [Equation 5]

[0157]

[0159] For example, if the UE is not provided with the IntraCellGuardBandsPerSCS parameter configuration, the carrier μ and the carrier size may be determined according to the requirements of the RF standard The nominal in-cell guard band and the CRB index of the RBS mode. Additionally, for example, if the above-mentioned nominal in-cell guard band and RBS mode do not include an in-cell guard band, the RBS of the corresponding carrier can be assumed to be 1.

[0160] For example, in Figure 9 , two LBT BWs (RBS 0, RBS1) can be configured in a single BWP922 within the single-carrier bandwidth. Here, a single guard band 913 can be configured between the two RBSs 911 and 913. The position of each of the two RBSs 911 and 913 can be determined based on the above-mentioned higher-layer parameters as shown in Figure 9 . Additionally, for example, when multiple BWPs 921 and 923 are configured within the single-carrier bandwidth, the RBSs associated with each BWP can be verified. Here, the RBSs corresponding to the first RBS (= s0, 912) and the last RBS (= s1, 911) of each BWP among the RBSs 911 and 912 within the carrier can be indexed by the s0 and s1 indices.

[0162] Figure 10 shows the unlicensed bands applicable to the present disclosure. Referring to Figure 10 , the NR-U band as the unlicensed band (e.g., NR) of a wireless communication system can be two frequency ranges: a low-frequency band of 7 GHz or less and a high-frequency band of 60 GHz. However, the said bands are merely examples and can be not limited thereto. For example, in Figure 10 , a 2.4 GHz band can be used for Industrial, Scientific and Medical (ISM), a 3.5 GHz band can be used for Citizen Broadband Radio Service (CBRS), and a band from 5 GHz to 7 GHz can be used for Unlicensed National Information Infrastructure (UNII). The UNII (5.925 GHz to 7.125 GHz) band can include multiple bands (UNII-1, UNII-2,..., UNII-8). For each of the multiple bands UNII (UNII-1, UNII-2,..., UNII-8) within UNII, different transmission powers, indoor / outdoor operations, maximum power Effective Isotropic Radiated Power (EIRP), and Dynamic Frequency Selection (DFS) requirements can be determined, but it can be not limited to a specific form.

[0163] The frequency band from 5 GHz to 6 GHz can be divided into non - overlapping 20 - MHz channel bandwidths. Here, channels with wide bandwidths such as 40 MHz, 80 MHz, and 160 MHz can be configured based on the boundaries. For example, a part of the 6 - GHz frequency band can coexist with systems using backhaul communication (UNII - 5, UNII - 7), satellite (UNII - 5), broadcast (UNII - 6, UNII - 8), and ultra - wideband (UWB) systems (UNII - 6). The number of channels in the UNII - 5 frequency band (5.925 to 6.425 GHz) can be 24, 12, 6, and 4 at 20 MHz, 40 MHz, 80 MHz, and 160 MHz respectively. In addition, the UNII - 5 frequency band (5.925 to 6.425 GHz) can be used outside indoor and protected areas. Here, indoor can be determined as EIRP 30 dBm (AP) and 24 dBm (UE), and outdoor can be determined as EIRP 36 dBm (AP) and 30 dBm (UE), but they are not limited to a specific form.

[0164] The channels described below can be part of a single carrier or multiple consecutive resource blocks (RBs) within the carrier. For example, the channel access process can be a process of verifying the channel based on sensing to perform transmission. In the case of performing the channel access process, the base station or UE can perform energy detection based on a time - slot unit, and if it is less than or equal to a preset value, it can determine that the channel is in an idle state. Hereinafter, a method of operating in an unlicensed frequency band based on the above operations is described.

[0165] Figure 11 A sidelink resource pool to which the present disclosure can be applied is shown. Refer to Figure 11 , multiple Tx resource pools (RPs) and Rx RPs can be configured for the UE. The resource pool can be identified by an identifier (ID) and added to or removed from the UE. In addition, for example, each resource pool configuration can be different. Specifically, the physical sidelink control channel (PSCCH), physical sidelink shared channel (PSSCH), and physical sidelink feedback channel (PSFCH) configurations can be different for each resource pool. In addition, the resource pool can be configured with the starting position of sub - channels within a sidelink bandwidth part (SL BWP) (which indicates the resource position), the number of RBs, and the sub - channel size according to frequency. In addition, in the resource pool, the position of time resources can be configured in a bitmap format. Here, except for the time slots used in the SSB and uplink, time resources can be mapped, and the time resources can be repeatedly applied for each bit configured within a system frame number (SFN).

[0166] Specifically, for example, refer to Figure 11, the UE can determine the resource locations in a specific resource pool within the SL BWP. The subchannel size can represent a physical resource block (PRB) as the minimum unit for resource selection. Also, "SL-startRBsubchannelSize" can represent the starting RB of the subchannel within the SL BWP, "SL-RB-number" can represent the number of available RBs within the SL BWP, and "SL-SubchannelSize" can represent the size of a single subchannel. The UE can determine the number of subchannels to be used within the SL BWP based on the above parameters. Additionally, for example, the time-axis resources can be indicated in units of time slots by "sl-TimeResource". Specifically, for example, when the UE receives an indication of "0011111100" as a 10-bit indicator, the UE can use the resources of the time slots indicated by 1, excluding the time slots containing the reserved time slot SSB. Moreover, the UE can not use the time slots not included in the above subchannel RBs within the SL BWP, or the time slots indicated by 0 in "SL-TimeResource". For example, up to 4 SL BWPs can also be configured, and one of the configured BWPs can be activated and used. Also, within the SL BWP, up to eight Tx resource pools can be configured, and up to 16 Rx resource pools can be configured, which is not limited to a specific embodiment.

[0167] In addition, the UE can receive data and perform decoding, and can send hybrid automatic repeat request (HARQ) feedback as a response based on the reception success status. For example, the UE can determine whether decoding fails by combining the initial transmission and retransmission. In the current wireless communication system (such as NR), both the downlink (DL) and the uplink (UL) use the asynchronous HARQ incremental redundancy (IR) method. The base station can provide the HARQ feedback timing configuration to the UE through a radio resource control (RRC) message, and can flexibly indicate the HARQ feedback timing through DCI.

[0168] Specifically, for example, the base station can indicate the transmission timing to the UE through DCI. For example, K0 within the DCI can indicate the interval between the DCI sent to the physical downlink control channel (PDCCH) and the DL data sent to the physical downlink shared channel (PDSCH). Additionally, K1 within the DCI can indicate the interval between the reception of the PDSCH DL data and the UL HARQ feedback timing sent to the physical uplink control channel (PUCCH). Moreover, K2 within the DCI can indicate the interval between the reception of the PDCCH UL grant and the UL data sent to the physical uplink shared channel (PUSCH).

[0169] In addition, for example, even in sidelink communication, HARQ feedback operations can be considered. Specifically, the medium access control (MAC) entity of a UE can include at most one sidelink HARQ entity for sidelink shared channel (SL-SCH) transmission. The sidelink HARQ entity can maintain up to 16 sidelink processes. The sidelink process can be configured to enable the transmission of multiple MAC protocol data units (PDUs). For example, in resource allocation mode 2 where the UE directly determines sidelink resources, the UE can configure up to four sidelink processes for the transmission of multiple MAC PDUs. In addition, sidelink grants delivered to the MAC entity and information related to the sidelink grants can be configured in association with the sidelink processes. Each sidelink process can be used to send a single transport block (TB).

[0170] As another example, sidelink discontinuous reception (DRX) operations can be considered. Here, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) can be configured as a sidelink process within the sidelink HARQ entity of the UE, and operations based on the sidelink HARQ round-trip time timer can be performed. The sidelink DRX HARQ RTT timer can be configured differently based on at least one of HARQ feedback disable / enable, the presence or absence of a physical sidelink feedback channel (PSFCH), the presence or absence of retransmission resources within the SCI, and the HARQ feedback method (e.g., ACK / NACK, NACK only).

[0171] Figure 12 The sidelink DRX HARQ RTT timer applied to the present disclosure is shown. For example, Figure 12 it can be the case where, in a resource pool where the PSFCH is configured, HARQ feedback is enabled with a HARQ feedback enable indicator set to a first value within the SCI, and no retransmission resources are indicated. However, this is only a configuration for clarity of description and is not limited to the corresponding embodiments.

[0172] In Figure 12In the example, time slot 1210 may be a time slot in which PSFCH is configured, and time slot 2 1220 may be a time slot in which PSFCH is not configured. When the UE receives PSCCH and PSSCH in time slot 1 1210, the UE may send HARQ feedback in a sidelink time slot (time slot 3 1230) in which PSFCH is configured, which is two time slots later based on the configured sl-MinTimeGapPSFCH parameter. The UE may expect to receive a retransmission grant or a new grant based on HARQ feedback in the first time slot after PSFCH transmission, and therefore may perform operations based on a sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) which is a sidelink DRX timer configured by a higher layer parameter. For example, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) may refer to the minimum time before an assignment for HARQ retransmission is expected, and the UE may be in a sleep state during the corresponding time period. In addition, a sidelink DRX HARQ RTT timer (SL drx-HARQ-RTT-Timer) may be configured for each HARQ process. For example, for clarity of description, it is referred to as the sidelink DRX HARQ RTT timer below, but the sidelink DRX HARQ RTT timer performing the same function may also be represented by different names and may not be limited to a specific form. As another example, although the UE does not perform sidelink HARQ feedback transmission through UL transmission due to UL / SL prioritization, the UE may operate the sidelink DRX HARQ RTT timer (SL drx-HARQ-RTT-Timer) in the first time slot after the end of the PSFCH resource to receive a retransmission authorization.

[0173] For example, when retransmission resources are configured within the SCI, as a case where HARQ feedback is enabled within the resource pool in which the PSFCH is configured, the sidelink DRX HARQ RTT timer (SL drx-HARQ-RTT-Timer) can be derived through the subsequent retransmission resources within the SCI. As another example, when HARQ feedback is disabled and there are no retransmission resources within the SCI, the UE can perform a sidelink DRX HARQ RTT timer (SL drx-HARQ-RTT-Timer) operation after the PSFCH. On the other hand, when HARQ feedback is disabled and there are retransmission resources within the SCI, the UE can operate the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-timer) from the received PSSCH to the subsequent retransmission resources within the SCI, and this can reduce the power consumption of the UE.

[0174] Figure 13 A method for operating a sidelink timer in a resource pool where PSFCH is not configured is shown. Refer to Figure 13 , a resource pool where PSFCH is not configured can be considered. Since the UE does not perform HARQ feedback operations in the corresponding resource pool, the UE can operate the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-timer) after the PSCCH 1310 indicated in the SCI. For example, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-timer) can start based on a slot unit, and the timer length can be configured based on the slot unit. In addition, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) can operate differently depending on whether there are retransmission resources in the SCI. Specifically, for example, in the case where there are no retransmission resources in the SCI: A. The operation can be different depending on whether there are retransmission resources in the SCI. When there are no retransmission resources in the SCI, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) can operate without considering HARQ feedback enable / disable. On the other hand, when there are retransmission resources in the SCI, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) can be set to the time from the PSSCH to the subsequent retransmission resources. As another example, two sidelink DRX HARQ RTT timer values (sl-drx-HARQ-RTT-Timer) can be set for the presence and absence of PSFCH in the resource pool, and it is not limited to a specific embodiment.

[0175] Figure 14 A sidelink HARQ feedback operation applied to the present disclosure is shown. Refer to Figure 14 , when the Rx UE receives the PSSCH 1410 in slot n, the Rx UE can determine the PSFCH timing to perform HARQ feedback according to the configured higher layer parameter (e.g., sl-MinTimeGapPSFCH). Specifically, for example, in Figure 14 , as a higher layer parameter, sl-MinTimeGapPSFCH can be configured with three slots. The UE can perform HARQ feedback in the first PSFCH timing 1430, which appears after slot n + 3, three slots starting from slot n. Specifically, for example, the case where the PSFCHS period is set to 4 in the resource pool can be considered. However, this is only an example for clarity of description, and the present disclosure is not limited thereto. The PSFCH timing can be configured for every four sidelink slots based on the PSFCH period 4. InFigure 14 In this case, when the UE receives the PSSCH 1410 in time slot n, the UE may perform HARQ feedback in time slot n+5, where the first PSFCH occasion 1430 occurs after sl-MinTimeGapPSFCH.

[0176] Figure 15 Shows the PSSCH-PSFCH mapping for HARQ feedback transmission applied to the present disclosure. Refer to Figure 15 , the sidelink HARQ feedback resources may not be explicitly indicated and may be implicitly configured. The UE may derive the PSSCH and PSFCH association relationship based on preconfigured higher layer parameters, and may perform HARQ feedback through the PSFCH resources associated with the received PSSCH. Specifically, for example, in Figure 15 the number of subchannels (N subch ,sl-NumSubchannel) within the resource pool is 4, and the PSFCH occasion may be configured for every four time slots according to sl-PSFCH-period. Here, the number of PSSCH time slots associated with a single PSFCH occasion may be 4. However, this is merely an example for clarity of description and is not limiting to the corresponding embodiments.

[0177] The UE may perform PSFCH resource mapping according to the PSSCH through configuration parameters. In addition, the physical resource blocks (PRBs) within the PSFCH occasion for HARQ feedback may be indicated as 0 or 1 as a bit string. For example, the total number of PRBs within the PSFCH occasion for HARQ feedback may be 80. Here, the 80 PRBs for HARQ feedback may represent the PRBs indicated as 1 in a bit string from 10 to 270 bits. Based on the following Equation 6, the 80 PRBs within a PSFCH occasion for HARQ feedback may be assigned to the time slot and subchannel associated with the PSFCH.

[0178] [Equation 6]

[0179]

[0181] Here, represents the time slot number associated with the PSFCH, and j((0≤j<N subch ) represents the number of the subchannel. In addition, represents by dividing the number of PRBs for HARQ feedback A value obtained by dividing by the number of subchannels and the number of time slots associated with the PSFCH. That is, for each subchannel of the time slot associated with the PSFCH PRBs for HARQ feedback within the PSFCH occasion can be assigned For example, in Figure 15 if the number of time slots associated with the PSFCH is four and there are four subchannels, there can be 16 subchannels. Here, if the number of PRBs for HARQ feedback is 80, five PRBs for each subchannel can be used for HARQ feedback.

[0182] The UE selects resources for transmitting HARQ feedback within the PSFCH PRBs associated with the subchannels. Specifically, in each PRB has two cyclic shift (CS) pairs and when sl-PSFCH-CandidateResourceType is set to the number of PSFCH candidate resources associated with a specific subchannel can be derived as shown in Equation 7.

[0183] [Equation 7]

[0184]

[0186] Here, can be 20, and the numbers of the 20 candidate resources can be determined according to the CS order after PRB ascending order. The UE can select the PSFCH resources according to the index derived from Equation 8 below. As another example, when sl-PSFCH-CandidateResourceType is set to the number of PSFCH candidate resources can be configured differently.

[0187] [Equation 8]

[0188]

[0190] Here, P ID represents the physical layer source ID indicated by the SCI format 2-A / 2-B / 2-C, and M ID represents the higher layer UE ID for multicast HARQ ACK-NACK feedback. For example, in the case of unicast or multicast HARQ only NACK, M ID can be 0.

[0192] In addition, for example, the UE may perform a Listen Before Talk (LBT) process for channel occupancy in an unlicensed band. The LBT process may be a process of determining whether a channel is occupied by a Clear Channel Assessment (CCA) check before using the channel. The CCA check may be an operation of performing sensing during a CCA period. The CCA check may use Energy Detection (ED) to detect whether there is another signal in the channel. Specifically, if the energy detected during the CCA period (e.g., received signal strength, Received Signal Strength Indicator (RSSI)) is less than the ED threshold, the UE may determine that the channel is not occupied and may occupy the channel during the COT. On the other hand, if the energy detected during the CCA period is greater than the ED threshold, the UE may determine that the channel is occupied, and the CCA period may be extended until the channel is unoccupied. For example, LBT may be a mandatory process for 5 GHz and 60 GHz unlicensed band operations in Europe and Japan, and may not be defined as a basic process in the United States and China. The CCA slot duration may be 9 μs at 5 GHz and 5 μs at 60 GHz, but is not limited thereto. More specifically, the initial CCA may be set to a multiple of 5 μs at 60 GHz, the extended CCA may be set to 8 + m × 5 μs, and m may be configured as a backoff counter. In addition, the ED threshold for a 20 MHz channel bandwidth may be set to -72 dBm at 5 GHz and may be set to -47 dBm at 60 GHz, but is not limited thereto.

[0193] In addition, for example, the LBT category may consider categories 1 to 4 shown in Table 10 below, but is not limited thereto.

[0194] [Table 10]

[0195]

[0196] Here, the UE can use different categories according to the transmission purpose. For example, the UE and the base station can use Cat 4 LBT for data transmission purposes in Licensed-Assisted Access (LAA). On the other hand, when the base station sends a discovery reference signal, Cat 2 LBT can be used. As another example, in NR-U, if the transmission interval between DL and UL in the COT sharing operation is less than 16 μs when the base station occupies the channel, the UE can perform Cat 1 LBT without CCA checking. On the other hand, if the transmission interval between DL and UL is greater than 16 μs and less than 25 μs, the UE can perform Cat 2 LBT using short sensing. In addition, if the transmission interval between DL and UL is greater than 25 μs, the UE can perform Cat 4 LBT for general data transmission. Here, although LAA can support one DL / UL exchange, NR-U can support multiple DL / UL handovers.

[0198] In addition, for example, continuous transmission may be restricted in the unlicensed band in a specific region (e.g., Europe, Japan). That is, the Maximum Channel Occupation Time (MCOT), which is the time for which the UE can continuously use the channel, may be limited. For example, according to the priority level in the 5 GHz band, the MCOT can be restricted to 2 ms, 4 ms, or 6 ms. In addition, the MCOT can be restricted to 9 ms in the 60 GHz band, but is not limited thereto. In addition, for example, the UE and the base station can share the COT in the 5 GHz and 60 GHz bands. That is, downlink (DL) and uplink (UL) transmissions are possible within the COT. Specifically, when the base station occupies the channel through the LBT process and performs a DL transmission to the UE, the UE can immediately perform a UL transmission without CCA checking.

[0199] After successful LBT, the UE can occupy the channel and use the channel within the MCOT. Here, due to the flexible time slot structure such as micro time slots, the current wireless communication system (e.g., NR) may perform the transmission and reception operations in the unlicensed band less efficiently compared to the existing wireless communication system (e.g., LTE). Therefore, the COT can be shared between the base station and the UE, and the UE can improve the spectrum efficiency or can perform a fast response operation.

[0200] Figure 16 The COT structure applied to the present disclosure is shown. For example, the wireless communication system can support a single DL / UL handover or multiple DL / UL handovers. Specifically, for example, referring to Figure 16For (a) of , a single DL / UL switch can be a configuration for performing a single DL / UL switch within the COT. Due to the small guard band, a single DL / UL switch can reduce overhead. If the interval between DL and UL is greater than 16 μs, multiple LBT procedures may not be performed. However, in a single DL / UL switch, after a specific period of time after DL, the UL operation is only configured once, so delays in HARQ feedback and UL scheduling may occur. For example, even if an attempt is made to perform Cat 4 LBT and it fails during the UL operation, a UL scheduling delay may occur. Considering the above, the single DL / UL switch COT configuration can be applicable to enhanced mobile broadband (eMBB) services with high throughput and flexible latency requirements, but is not limited thereto.

[0201] In addition, for example, referring to Figure 16 For (b) of , a multi-DL / UL switch COT configuration can be configured with multiple opportunities to perform UL. Therefore, in a multi-DL / UL switch COT configuration, the HARQ feedback configuration can be simple. In the case of performing sensing according to UL transmission LBT (i.e., if the interval between UL and DL is greater than 16 μs), the multi-DL / UL switch COT configuration can ensure channel utilization. Since the base station performs a CCA check for DL transmission, if LBT is performed at a relatively close time, LBT can be successful. However, since the multi-DL / UL switch COT configuration includes multiple guard bands, multiple LBT procedures may need to be performed. Considering the above, the multi-DL / UL switch COT configuration can be applicable to massive machine type communication (mMTC) with latency-sensitive services and low-load services, such as ultra-reliable low-latency communication (URLLC) or enhanced V2X (eV2X), but is not limited thereto.

[0202] In addition, for example, to limit interference between inter-RAT and intra-RAT in unlicensed band operation, power (EIRP, PSD) can be limited in all regions and bands, as described above.

[0203] In addition, for example, the occupied channel bandwidth (OCB) can be defined as the bandwidth that includes 99% of the signal power in a specific region. This can indicate that most of the channel bandwidth needs to be used when accessing a channel in the unlicensed band. For example, at 5 GHz, the OCB can be 70% to 100% of the nominal channel bandwidth (NCB), and at 60 GHz, the OCB can be 80% to 100% of the NCB, but is not limited thereto.

[0204] In addition, as an unlicensed band scenario, Licensed-Assisted Access (LAA), existing unlicensed band communication (LTE-unlicensed), and multi fire technology can be defined for operation in the 5 GHz band. However, current unlicensed band communication (LTE-unlicensed) can be designed by considering multiple frequency bands, such as 2.4 GHz, 3.5 GHz, 5 GHz, 6 GHz, 37 GHz, and 60 GHz, but not limited thereto. In addition, for example, the unlicensed band can be divided into a band of 7 GHz or less and a mmWave band. 7 GHz can include 2.4, 3.5, 5, and 6 GHz, and the mmWave band can include 37 GHz and 60 GHz, but not limited thereto.

[0207] For example, sidelink communication can support improved V2X applications. In addition, sidelink communication can support proximity-based public safety and commercial services, but not limited thereto. Sidelink communication can support operations to improve power consumption in the UE to increase data reliability by using limited battery and partial sensing, discontinuous reception (DRX), and inter-UE coordinated operation, but not limited thereto.

[0208] In addition, operations considering the increased data rate (increased sidelink data rate) in sidelink communication can be performed. For example, the increased data rate can be used to share sensor information of big data, such as video, between vehicles performing autonomous driving at a high level. The data rate can be increased based on methods such as sidelink carrier aggregation or using the sidelink unlicensed band, but not limited to the corresponding embodiments. In addition, operations supporting a new carrier frequency for sidelink communication can be considered. Through FR2 sidelink operation with a new frequency and wide bandwidth, the data rate can be increased. For example, currently, the use of the Intelligent Transportation System (ITS) band may be limited to applications associated with ITS security. However, if operations such as using the unlicensed band are supported in sidelink communication, commercial services can be expected with improved performance. In addition, for example, a V2X scenario where LTE V2X and NR V2X UEs share the same frequency channel can be considered. A method for different types of UEs to effectively perform resource assignment without adversely affecting each other may be required, but not limited thereto.

[0209] Next, considering the above description of the HARQ DRX timer operation according to the SL-U operation. For example, the UE can perform the LBT procedure in SL-U and can perform sidelink transmission in the COT based on the success of LBT. On the other hand, if the UE performs the LBT procedure in SL-U and does not occupy the channel due to LBT failure, the UE may not perform sidelink transmission. The following describes the HARQ DRX timer operation considering the above.

[0211] For example, the UE can perform the LBT operation in the unlicensed band. If the channel is occupied based on the success of LBT, sidelink transmission can be performed, and if the channel is not occupied, sidelink transmission may not be performed. If the UE fails in LBT, the UE may not perform HARQ feedback transmission via the PSFCH. In addition, as described above, in the unlicensed band, other communication technologies (e.g., Wi-Fi) can coexist, and the channel needs to be used equally, so requirements such as MCOT can be considered. Specifically, for example, through the LBT procedure, if the received signal strength does not exceed a specific power threshold, the UE can occupy and use the channel during a limited time period.

[0212] Here, the existing HARQ feedback operation can be configured semi-statically. The PSFCH timing of HARQ feedback can be semi-statically configured, but needs to be improved considering the SL-U operation. For example, the HARQ feedback operation can support the operation of configuring multiple consecutive or non-consecutive PSFCH transmission opportunities by considering SL-U. As another example, the HARQ feedback operation can support the dedicated PSFCH resource indication operation by considering SL-U. As another example, the HARQ feedback operation can support the dedicated PSSCH resource indication operation by considering SL-U. However, this is only an example, and the present disclosure is not limited thereto.

[0213] For example, the multiple PSFCH transmission opportunities considering SL-U can represent at least one of the semi-statically configured PSFCH timings. As another example, the multiple PSFCH transmission opportunities considering SL-U can represent at least one of the semi-statically configured PSFCH timing and the dynamically indicated dedicated PSFCH resource. For example, the dynamically indicated HARQ feedback resource can be a method of indicating the HARQ feedback resource using the SCI. Here, the SCI can indicate the PSSCH resource or a specific resource in the semi-statically configured PSFCH timing as the HARQ feedback resource.

[0214] Specifically, for example, as the multiple HARQ feedback transmission opportunities considering SL-U, a semi-static PSFCH configuration or a semi-static PSFCH configuration and a dynamic PSFCH / PSSCH resource indication operation can be considered, which can be as shown in Table 11 below. In addition, as a single HARQ feedback transmission opportunity, a dynamic PSSCH resource indication for HARQ feedback can be considered. In addition, as a single HARQ feedback transmission opportunity, a semi-static PSFCH configuration can be considered, which can be as shown in Table 11 below.

[0215] [Table 11]

[0216]

[0217] In addition, the operation of the sidelink DRX timers (sl-drx-HARQ-RTT-Timer, sl-drx-RetransmissionTimer) for additional PSFCH transmission opportunities may need to be considered and described accordingly.

[0218] For example, Figure 17 illustrates a method for configuring multiple PSFCH transmission opportunities applied to the present disclosure and a method for configuring the sidelink DRX timer based thereon. Referring to Figure 17 , the PSFCH resources 1710, 1720, and 1730 can be semi-statically configured in the sidelink time slot. The intervals between the PSFCH resources 1710, 1720, and 1730 can be semi-statically configured by a parameter indicating the PSFCH period (sl-PSFCH-period). For example, in Figure 17 , two time slots can be used to configure the PSFCH interval. Specifically, the PSFCH resources can be configured in the sidelink time slot number in which "logical sidelink time slot number modulo sl-PSFCH-Period" becomes 0. However, for the sake of clarity of description, this is only one configuration, but the present disclosure is not limited thereto.

[0219] Here, the sidelink DRX timer may be configured to operate variably. The sidelink DRX timer may be configured to reduce the power consumption of the Rx UE by considering the operations of sending and receiving retransmission authorizations between the Tx UE and the Rx UE. For example, considering the above situation, the sidelink DRX timer needs to operate at a specific time point among multiple HARQ feedback transmission opportunities. The multiple HARQ feedback transmission opportunities may be opportunities for the Tx UE to determine ACK / NACK for sidelink data based on HARQ feedback. The Tx UE may generate a retransmission authorization by considering the time point when HARQ feedback information is actually received during the HARQ feedback transmission opportunity. Therefore, the Rx UE may operate the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) as the sidelink DRX timer after a successful HARQ feedback transmission during the HARQ feedback transmission opportunity. Then, the Rx UE may operate the sidelink DRX retransmission timer (sl-drx-RetransmissionTimer) as the sidelink DRX timer to receive a retransmission authorization based on whether the decoding of the received data is successful. For example, the sidelink DRX retransmission timer may be a timer for the maximum period before receiving a sidelink retransmission.

[0220] As another example, when multiple HARQ feedback transmission opportunities are configured, the operation of the sidelink DRX timer may be fixed to a specific time point. For example, the Tx UE may not receive HARQ feedback within the configured multiple HARQ feedback transmission opportunities, and the Tx UE may not identify the reason for the failure of HARQ feedback reception. Specifically, for example, when the Rx UE fails in LBT, the Rx UE may not perform HARQ feedback transmission to the Tx UE. As another example, the Rx UE may not perform sidelink HARQ feedback transmission through UL operation based on UL / SL priority operation. As another example, the Rx UE may not perform HARQ feedback transmission due to poor channel conditions, but this is not limited thereto.

[0221] Considering the above situation, the sidelink DRX timer may be configured to execute in a specific transmission opportunity among the configured multiple HARQ feedback transmission opportunities, and based on this, retransmission authorization sending and receiving may be performed. Specifically, for example, the sidelink DRX timer may operate in the last transmission opportunity among the HARQ feedback transmission opportunities. As another example, the sidelink DRX timer may operate in different transmission opportunities and is not limited to a specific embodiment.

[0222] As another example, Figure 18A method is shown for configuring multiple HARQ feedback transmission opportunities through semi-statically configured PSFCH configurations applied to the present disclosure and performing sidelink DRX timer operations based thereon. Referring to Figure 18 , the Rx UE can receive the SCI and data from the Tx UE through the PSCCH / PSSCH 1810 in slot n, and the Rx UE can 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 as the minimum time gap for the PSFCH. In addition, when multiple HARQ feedback transmission opportunities are configured and enabled in the UE, the Rx UE can utilize the resources capable of sending HARQ feedback to perform the nth HARQ feedback transmission in the PSFCH occasion 1830 of slot n+6.

[0223] For example, it is necessary to configure sidelink DRX timer operations considering the above situation. Specifically, the sidelink DRX timer can be variably determined. The sidelink DRX timer can operate after a successful LBT process and after sending HARQ feedback during a HARQ feedback transmission opportunity. Referring to Figure 18 , a situation can be considered where the Rx UE does not send HARQ feedback due to LBT failure in the PSFCH occasion 1820 of slot n+4 and successfully sends HARQ feedback due to LBT success in the PSFCH occasion 1830 of slot n+6. However, this is only an example for clarity of description, and the present disclosure is not limited thereto. That is, the Rx UE can perform HARQ feedback transmission in the PSFCH occasion 1830 of slot n+6. Here, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) as the sidelink DRX timer can operate after the PSFCH occasion 1830 of sending HARQ feedback. If the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) expires and the data of the corresponding sidelink process is not successfully decoded, or the HARQ feedback is NACK, the RxUE can operate the sidelink DRX HARQ retransmission timer (sl-drx-HARQ-RetransmissionTimer) and can expect to receive a retransmission grant through PSCCH monitoring.

[0224] As another example, the sidelink DRX timer can be fixed after a specific HARQ feedback transmission opportunity in the HARQ feedback transmission opportunity. For example, the sidelink DRX timer can operate after the last HARQ feedback transmission opportunity. Referring to Figure 18, it is possible to consider the case where HARQ feedback transmission is successfully performed based on the success of LBT in the PSFCH opportunity 1820 at time slot n+4. However, even in the above case, the sidelink DRX timer is fixed to operate after the last HARQ feedback transmission opportunity. Therefore, after the PSFCH opportunity 1830 that exists in time slot n+6 as the last HARQ feedback opportunity, the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) can be operated. If the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) expires and the data of the corresponding sidelink procedure is not successfully decoded, or the HARQ feedback is NACK, the Rx UE can operate the sidelink DRX HARQ retransmission timer (sl-drx-HARQ-RetransmissionTimer) and can expect to receive a retransmission grant through PSCCH monitoring. For example, although it is described in Figure 18 based on the case where the number of multiple HARQ feedback transmission opportunities is two, two or more HARQ feedback transmission opportunities can be configured, and it is not limited thereto.

[0225] In addition, for example, the method for indicating multiple HARQ feedback transmission opportunities can be configured in various ways. For example, the consecutive PSFCH opportunities can be indicated by RRC and N fixable PSFCH opportunities can be indicated. That is, the Rx UE can obtain HARQ feedback transmission opportunities in N consecutive PSFCH opportunities starting from a specific PSFCH opportunity.

[0226] As another example, in the case of indicating non-consecutive PSFCH opportunities, the UE can obtain the offset parameter of the nth PSFCH opportunity through RRC. For example, the Rx UE can obtain the offset parameter of the second PSFCH opportunity (e.g., sl-2ndMinTimeGapPSFCH), and based on this, can obtain HARQ feedback transmission opportunities. As another example, the UE can obtain the above consecutive PSFCH opportunities or offset values through SCI instead of RRC, and it is not limited to a specific form.

[0227] Figure 19 shows a method of applying the present disclosure to configure multiple HARQ feedback transmission opportunities by using semi-statically configured PSFCH opportunities and dedicated PSFCH resources, and operating the sidelink DRX timer based on this. For example, in Figure 19 , the dedicated PSFCH resource can be a specific physical resource block (PRB) within a semi-statically configured PSFCH opportunity or a specific resource within a PSSCH.

[0228] Specifically, for example, referring toFigure 19 In (a), the dedicated PSFCH resource may be a specific PRB resource in a semi-statically configured PSFCH occasion. For example, the dedicated PSFCH resource may be indicated by an SCI, and the corresponding PSFCH resource may be added to the HARQ feedback transmission opportunity. For example, the sidelink DRX timer may operate in a fixed form after a specific HARQ feedback transmission opportunity in the HARQ feedback transmission opportunity. For example, the sidelink DRX timer may operate after the last HARQ feedback transmission opportunity, but is not limited thereto. In Figure 19 In (a), the UE may receive an SCI and data through the PSCCH / PSSCH in slot n. The Rx UE may identify that the PSFCH occasion 1910 located in slot n + 4 is a HARQ feedback transmission opportunity associated with the PSSCH received in slot n. In addition, the Rx UE may identify that the dedicated PSFCH resource 1920 indicated by the SCI is a HARQ feedback transmission opportunity.

[0229] That is, the Rx UE may identify 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, for example, the Rx UE may not send HARQ feedback due to an LBT failure in the first HARQ feedback transmission opportunity 1910 located in slot n + 4, and may succeed in LBT in the second HARQ feedback transmission opportunity 1920 located in slot n + 8, and may accordingly perform HARQ feedback transmission. However, this is only an example for clarity of description, and the present disclosure is not limited thereto.

[0230] To receive a retransmission grant, the Rx UE may perform HARQ feedback in time slot n+8, which is the second and last PSFCH transmission opportunity, and then the Rx UE may operate the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) as the sidelink DRX timer. If the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) expires as a timer and the data of the corresponding sidelink procedure is not successfully decoded, or the HARQ feedback is NACK, the Rx UE may operate the sidelink DRX HARQ retransmission timer (sl-drx-HARQ-RetransmissionTimer) and may expect to receive a retransmission grant by monitoring the PSCCH. In addition, for example, dedicated PSFCH resources may not appear in time before the associated first PSFCH resource. For example, since the PSFCH resources semi-statically configured by the network are set by sl-MinTimeGapPSFCH by considering the PSFCH period and the Tx / Rx switching time, additional dedicated PSFCH resources may have a higher time priority than the first PSFCH resource.

[0231] In addition, for example, referring to Figure 19 (b) thereof, dedicated PSFCH resources may be indicated within the PSSCH resource 1930. For example, the PSFCH resources indicated within the PSSCH resource 1930 may be indicated by the SCI, and the corresponding PSFCH resources may be added to the HARQ feedback transmission opportunity.

[0232] In Figure 19 (b) thereof, the UE may receive the SCI and data through the PSCCH / PSSCH in time slot n, and the Rx UE may recognize that the PSFCH occasion 1910 located in time slot n+4 is the HARQ feedback transmission opportunity associated with the PSSCH received in time slot n. In addition, the Rx UE may recognize that the dedicated PSFCH resources within the PSSCH resource 1930 indicated by the SCI are the HARQ feedback transmission opportunity. That is, the Rx UE may recognize that the PSFCH occasion 1910 located in time slot n+4 may be the first HARQ feedback transmission opportunity, and the PSFCH resources within the PSSCH 1930 located in time slot n+6 may be the second HARQ feedback transmission opportunity. Here, for example, the Rx UE may not send HARQ feedback due to an LBT failure in the first HARQ feedback transmission opportunity 1910 located in time slot n+4, and may succeed in LBT in the second HARQ feedback transmission opportunity located in time slot n+6, and may accordingly perform HARQ feedback transmission. However, this is only an example for clear description, and the present disclosure is not limited thereto.

[0233] To receive retransmission authorization, the Rx UE may perform HARQ feedback in slot n+6 of the second and last PSFCH transmission opportunity. Then, the Rx UE may use the sidelink DRX timer as a timer to operate the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer). If the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) expires as a timer and the data of the corresponding sidelink procedure is not successfully decoded, or the HARQ feedback is NACK, the Rx UE may operate the sidelink DRX HARQ retransmission timer (sl-drx-HARQ-RetransmissionTimer) and may expect to receive retransmission authorization by monitoring the PSCCH.

[0234] In addition, for example, referring to Figure 19 (c), the dedicated PSFCH resource may be indicated within the PSSCH resource 1940. For example, the PSFCH resource indicated within the PSSCH resource 1940 may be indicated by the SCI, and the corresponding PSFCH resource may be added to the HARQ feedback transmission opportunity. In Figure 19In (c) above, the UE can receive the SCI and data through the PSCCH / PSSCH in time slot n. The Rx UE can identify that the PSFCH opportunity 1910 in time slot n+4 is the HARQ feedback transmission opportunity associated with the PSSCH received in time slot n. In addition, the Rx UE can identify that the dedicated PSFCH resource within the PSSCH resource 1940 indicated by the SCI is the HARQ feedback transmission opportunity. Here, the dedicated PSFCH resource within the PSSCH resource 1940 can be located within time slot n+3. That is to say, the dedicated PSFCH resource within the PSSCH resource 1940 in time slot n+3 can be the first HARQ feedback transmission opportunity, and the PSFCH resource 1910 in time slot n+4 can be the second HARQ feedback transmission opportunity. Here, for example, the Rx UE may not send HARQ feedback due to the LBT failure in the first HARQ feedback transmission opportunity in time slot n+3, and may succeed in the LBT in the second HARQ feedback transmission opportunity 1910 in time slot n+4, and can perform the HARQ feedback transmission. However, this is only an example for clear description, and the present disclosure is not limited thereto. To receive the retransmission authorization, the Rx UE can perform HARQ feedback in time slot n+4 which is the second and last PSFCH transmission opportunity, and the Rx UE can use the sidelink DRX timer as a timer to operate the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer). If the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) as a timer expires and the data of the corresponding sidelink procedure is not successfully decoded or the HARQ feedback is NACK, the Rx UE can operate the sidelink HARQ retransmission timer (sl-drx-HARQ-RetransmissionTimer), and can expect to receive the retransmission authorization through PSCCH monitoring.

[0235] As another example, the case where HARQ feedback is performed only through the semi-statically configured PSFCH can be considered. For example, HARQ feedback can be performed in one HARQ feedback transmission opportunity, and the sidelink DRX operation can be performed based on this. However, considering the MCOT limitation in SL-U, the HARQ feedback operation may be restricted, and for this, the operation may need to be improved.

[0236] Specifically, for example, Figure 20 shows the dedicated PSSCH resource for HARQ feedback considering a single HARQ feedback transmission opportunity applied to the present disclosure. Refer to Figure 20, the Rx UE can receive the SCI and data through the PSCCH / PSSCH in slot n. Here, the SCI can indicate that the HARQ feedback PSSCH resource 2010 is used as the PSFCH resource for HARQ feedback. The Rx UE can perform HARQ feedback through the HARQ feedback PSSCH resource 2010. For example, when multiple HARQ feedback transmission opportunities are prohibited, the Rx UE can send HARQ feedback in the HARQ feedback PSSCH resource 2010 indicated by the SCI, and can not perform HARQ feedback transmission in the PSFCH resource 2020 in slot n+4 associated with the PSSCH in slot n. The Rx UE can operate the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) as a timer after the indicated HARQ feedback PSSCH resource 2010. If the sidelink DRX HARQ RTT timer (sl-drx-HARQ-RTT-Timer) as a timer expires and the data of the corresponding sidelink process is not successfully decoded or the HARQ feedback is NACK, then the Rx UE can operate the sidelink DRX HARQ retransmission timer (sl-drx-HARQ-RetransmissionTimer), and can expect to receive a retransmission grant through PSCCH monitoring.

[0237] Here, for example, as shown in Table 12 below, the Tx UE can receive HARQ information from the physical layer in the PSFCH reception opportunity according to the PSSCH transmission, and in the case of not receiving this information, can deliver NACK in the corresponding sidelink process. Moreover, if the Tx UE does not receive the HARQ feedback information in the PSFCH reception opportunity, the Tx UE can increase the counter (e.g., numConsecutiveDTX). Here, if the corresponding counter (e.g., numConsecutiveDTX) reaches the threshold (e.g., sl-maxNumConsecutiveDTX), a HARQ-based sidelink radio link failure (RLF) may occur. However, Table 12 is only an example, and the present disclosure is not limited thereto.

[0238] If a sidelink RLF occurs, the Tx UE (source UE) with the PC5-RRC link established can release the Rx UE (destination UE), the data radio bearer (DBR), and the signaling radio bearer (SRB), and can delete the sidelink configuration. Similarly, the Tx UE can reset the MAC, and can release the Rx UE and the PC5-RRC.

[0239] [Table 12]

[0240]

[0242] Side-link RLF can be a process of detecting problems in channel conditions / physical layer and the configured configuration. For example, in the SL-U environment, due to LBT failure, HARQ feedback transmission may be impossible, and this situation may be different from RLF, and the operation of SL-U may need to be considered.

[0243] Specifically, for example, when multiple HARQ feedback transmission opportunities are configured, if, based on the bundling of multiple HARQ feedback transmission opportunities, no HARQ feedback is received in all HARQ transmission opportunities, the counter of RLF (NumConsucctiveDTX) can be configured to increase. That is, since LBT failure is not a failure according to channel conditions, the determination of RLF can be performed based on the entire multiple HARQ feedback transmission opportunities.

[0244] Figure 21 The HARQ feedback transmission opportunity bundling operation to which the present disclosure is applied is shown. Refer to Figure 21 , the Tx UE can send SCI and data through PSCCH / PSSCH in slot n. Here, in slot n, multiple PSFCH opportunities associated with PSCCH / PSSCH can be configured semi-statically. For example, in Figure 21 , although the first PSFCH opportunity 2110 and the second PSFCH opportunity 2120 are configured as multiple HARQ feedback transmission opportunities, for the sake of clear description, they are provided as examples, and the present disclosure is not limited thereto. That is, the number of multiple HARQ feedback transmission opportunities can be configured to be two or more.

[0245] Refer to Figure 21, the Tx UE and the Rx UE may bind the HARQ feedback transmission opportunity and may perform HARQ feedback transmission and reception. The Tx UE may determine whether to increment a counter (numConsucctiveDTX) for RLF based on the HARQ feedback transmission opportunity binding. Specifically, for example, if a PSSCH transmission corresponding to a source layer-2 ID and destination layer-2 ID pair occurs, the MAC entity of the UE may perform a HARQ-based sidelink RLF detection procedure. For example, the UE may configure and receive a counter (numConsecutiveDTX) for RLF, a threshold (sl-maxNumConsecutiveDTX) for RLF, and HARQ feedback transmission opportunity binding information based on a higher layer configuration. The UE may not receive HARQ feedback for each PSFCH reception occasion 2110, 2120 associated with the PSSCH transmission, and if the corresponding PSFCH reception occasion is the last occasion of the HARQ feedback transmission opportunity binding, the counter (numConsecutiveDTX) may be incremented by 1. On the other hand, if the corresponding PSFCH reception occasion is not the last occasion of the HARQ feedback transmission opportunity binding, the counter (numConsecutiveDTX) may not be incremented. In addition, for example, if there is a HARQ feedback reception in the PSFCH reception occasions associated with the PSSCH transmission, the UE may initialize the counter (numConsecutiveDTX) to 0. If the counter (numConsecutiveDTX) reaches the threshold (maxNumConsecutiveDTX) for RLF, the UE may indicate to the higher layer that sidelink RLF has been detected.

[0246] Specifically, for example, in Figure 21Among them, although the Tx UE does not receive HARQ feedback in the first PSFCH opportunity 2110, the Tx UE may not increment the counter (numConsecutiveDTX). If the UE does not receive HARQ feedback even in the second PSFCH opportunity 2120 as the last opportunity, the UE may increment the counter (numConsecutiveDTX) by 1. On the other hand, if the Tx UE receives HARQ feedback in the first PSFCH opportunity 2110, the Tx UE may not increment the counter (numConsecutiveDTX), regardless of whether the Tx UE receives HARQ feedback in the second PSFCH opportunity 2120. Moreover, if the Tx UE does not receive HARQ feedback in the first PSFCH opportunity 2110 and receives HARQ feedback in the second PSFCH opportunity 2120, the Tx UE may not increment the counter (numConsecutiveDTX). For example, in Figure 21 it is described based on the PSFCH reception opportunity, but it may not be limited thereto. For example, the above operations may include the HARQ feedback opportunity through the PSSCH / PSCCH. As another example, the counter (numConsecutiveDTX) may be configured to increment if there is no HARQ feedback at a specific opportunity that is not the last opportunity in the HARQ feedback transmission bundle.

[0247] Figure 22 is a flowchart showing the operations of a wireless UE to which the present disclosure can be applied. For example, the wireless UE may be the above UE and may not be limited to a specific form. Refer to Figure 22, a wireless UE may be configured with at least one HARQ feedback transmission opportunity (S2210). That is, the wireless UE may be configured with multiple HARQ feedback transmission opportunities or a single HARQ feedback transmission opportunity. The wireless UE may send HARQ feedback based on the at least one configured HARQ feedback transmission opportunity (S2220). The wireless UE may operate a sidelink DRX HARQ RTT timer based on the HARQ feedback transmission (S2230), and may receive a retransmission grant if the sidelink DRX HARQ RTT timer expires (S2240). Here, if the sidelink DRX HARQ RTT timer expires and the data of the sidelink procedure is not successfully decoded, or the HARQ feedback information is NACK, the wireless UE may be configured to receive a retransmission grant based on the sidelink DRX HARQ retransmission timer. Here, for example, the at least one HARQ feedback transmission opportunity may be configured as multiple based on at least one of a semi-static physical sidelink feedback channel (PSFCH) configuration and a dynamic PSFCH resource indication. For example, the sidelink DRX HARQ RTT timer may be variably configured based on the HARQ feedback transmission opportunity in which the HARQ feedback transmission among the multiple HARQ feedback transmission opportunities is successful. As another example, the sidelink DRX HARQ RTT timer may operate based on a specific HARQ feedback transmission opportunity among the multiple HARQ feedback transmission opportunities. Here, the specific HARQ feedback transmission opportunity may refer to the last HARQ feedback transmission opportunity among the multiple HARQ feedback transmission opportunities, but is not limited thereto.

[0248] As another example, the at least one HARQ feedback transmission opportunity may be a single HARQ feedback transmission opportunity. Here, the single HARQ feedback transmission opportunity may be indicated as a resource for HARQ feedback within the PSSCH. As described above, the sidelink DRX HARQ RTT timer may operate based on the resource for the HARQ feedback within the PSSCH.

[0249] Figure 23 FIG. is a diagram showing a base station and a terminal device to which the present disclosure can be applied.

[0250] The base station 2300 may include a processor 2320, an antenna unit 2312, a transceiver 2314, and a memory 2316.

[0251] The processor 2320 can perform baseband-related signal processing and can include a higher-layer processor 2330 and a physical-layer processor 2340. The higher-layer processor 2330 can perform operations of the Medium Access Control (MAC) layer, Radio Resource Control (RRC) layer, or higher layers thereof. The physical-layer processor 2340 can process operations of the Physical (PHY) layer (e.g., uplink received signal processing, downlink transmitted signal processing). In addition to performing baseband-related signal processing, the processor 2320 can also control the overall operation of the base station 2300.

[0252] The antenna unit 2312 can include at least one physical antenna, and in the case of including multiple antennas, can support multiple-input multiple-output (MIMO) transmission and reception. In addition, the antenna unit 2312 can support beamforming.

[0253] The memory 2316 can store the information processed by the calculation of the processor 2320 and software, operating system, applications, etc. related to the operation of the base station 2300, and can also include components such as buffers.

[0254] The processor 2320 of the base station 2300 can be configured to implement the operations of the base station in the embodiments described herein.

[0255] The terminal device 2350 can include a processor 2370, an antenna unit 2362, a transceiver 2364, and a memory 2366. For example, here, the terminal device 2350 can perform communication with the base station 2300. As another example, here, the terminal device 2350 can perform sidelink communication with another terminal device. That is, the terminal device 2350 of the present invention is a device capable of communicating with at least one of the base station 2300 and other terminal devices, and is not limited to communicating with a specific device.

[0256] The processor 2370 can perform baseband-related signal processing and can include a higher-layer processor 2380 and a physical-layer processor 2390. The higher-layer processor 2380 can process operations of the MAC layer, RRC layer, or higher layers thereof. The physical-layer processor 2390 can process operations of the PHY layer (e.g., downlink received signal processing, uplink transmitted signal processing). In addition to performing baseband-related signal processing, the processor 2370 can also control the overall operation of the terminal device 2350.

[0257] The antenna unit 2362 can include at least one physical antenna, and in the case of including multiple antennas, can support MIMO transmission and reception. In addition, the antenna unit 2362 can support beamforming.

[0258] The memory 2366 may store the computing and processing information of the processor 2370, as well as software, operating systems, applications, etc. related to the operation of the terminal device 2350, and may also include components such as buffers.

[0259] The terminal device 2350 according to an example of the present invention may be associated with a vehicle. For example, the terminal device 2350 may be integrated in the vehicle, may be located in the vehicle, or may be located on the vehicle. In addition, the terminal device 2350 according to the present invention may be the vehicle itself. In addition, the terminal device 2350 according to the present disclosure may be at least one of a wearable terminal, an AR / VR, an Internet of Things (IoT) terminal, a robot terminal, and a public safety terminal. The terminal device 2350 to which the present disclosure may be applied may include various types of communication devices that support interactive services using sidelinks for services such as, for example, Internet access, service execution, navigation, real-time information, autonomous driving, and safety and risk diagnosis. In addition, the terminal device 2350 may include an AR / VR device capable of performing sidelink operations or any type of communication device capable of performing a relay operation as a sensor.

[0260] Here, the vehicles to which the present invention is applied may include autonomous vehicles, semi-autonomous vehicles, and non-autonomous vehicles. Meanwhile, although the terminal device 2350 according to an example of the present invention is described as being associated with a vehicle, at least one UE may not be associated with a vehicle. However, it is provided only as an example and should not be construed as limiting the application of the present invention.

[0261] In addition, the terminal device 2350 according to an example of the present disclosure may include various types of communication devices capable of performing cooperation to support interactive services using sidelinks. That is, the terminal device 2350 may directly support interactive services using sidelinks and may serve as a cooperation device for supporting interactive services using sidelinks.

[0262] In addition, for example, the terminal device 2350 may be configured to have multiple HARQ feedback transmission opportunities or a single HARQ feedback transmission opportunity. The terminal device 2350 may send HARQ feedback based on at least one configured HARQ feedback transmission opportunity. The terminal device 2350 may operate a sidelink DRX HARQ RTT timer based on the HARQ feedback transmission, and may receive a retransmission grant if the sidelink DRX HARQ RTT timer expires. Here, if the sidelink DRX HARQ RTT timer expires and the data of the sidelink procedure is not successfully decoded, or the HARQ feedback information is NACK, the terminal device 2350 may receive a retransmission grant based on the sidelink DRX HARQ retransmission timer. Here, for example, at least one HARQ feedback transmission opportunity may be configured as multiple 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 the HARQ feedback transmission opportunity in which the HARQ feedback transmission is successful among the multiple 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 multiple HARQ feedback transmission opportunities. Here, the specific HARQ feedback transmission opportunity may refer to the last HARQ feedback transmission opportunity among the multiple HARQ feedback transmission opportunities, but is not limited thereto. As another example, the at least one HARQ feedback transmission opportunity may be a single HARQ feedback transmission opportunity. Here, the single HARQ feedback transmission opportunity may be indicated as a resource for HARQ feedback within the PSSCH. As described above, the sidelink DRX HARQ RTT timer may operate based on the resource for the HARQ feedback within the PSSCH.

[0263] In addition, various embodiments of the present disclosure may be implemented by hardware, firmware, software, or a combination thereof. In the case of implementation by hardware, the embodiments may be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), general purpose processors, controllers, microcontrollers, microprocessors, etc.

[0264] The scope of the present disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) for operating a method according to various embodiments on a device or computer, and non-transitory computer-readable media that are executable on the device or computer storing such software or instructions.

[0265] The various embodiments of the present disclosure are used to explain representative aspects of the present disclosure, rather than listing all possible combinations, and the descriptions made in the various embodiments can be applied independently or in combinations of two or more.

[0266] Industrial applicability

[0267] The above can be applied to other systems.

Claims

1. A wireless user equipment (UE) operating in a sidelink unlicensed band in a wireless communication system, the wireless UE comprising: At least one antenna configured to transmit and receive one or more wireless signals; At least one processor; And A memory configured to store instructions for the wireless UE when executed by the at least one processor, Wherein the wireless UE is configured to, Be configured with at least one hybrid automatic repeat 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 if the sidelink DRX HARQ RTT timer expires.

2. The wireless UE according to claim 1, wherein, If the sidelink DRX HARQ RTT timer expires and the data of the sidelink procedure is not successfully decoded or the HARQ feedback information is NACK, the wireless UE is configured to receive the retransmission grant based on a sidelink DRX HARQ retransmission timer.

3. The wireless UE according to claim 1, wherein, The at least one HARQ feedback transmission opportunity is configured as multiple based on at least one of a semi-static physical sidelink feedback channel (PSFCH) configuration and a dynamic PSFCH resource indication.

4. The wireless UE according to claim 3, wherein, The sidelink DRX HARQ RTT timer operates based on a HARQ feedback transmission opportunity in which the HARQ feedback transmission is successful among the multiple HARQ feedback transmission opportunities.

5. The wireless UE according to claim 3, wherein, The sidelink DRX HARQ RTT timer operates based on a specific HARQ feedback transmission opportunity among the multiple HARQ feedback transmission opportunities.

6. The wireless UE according to claim 1, wherein, The at least one HARQ feedback transmission opportunity is configured as one.

7. The wireless UE according to claim 6, wherein, The one HARQ feedback transmission opportunity is indicated as a resource for HARQ feedback within a physical sidelink shared channel (PSSCH).

8. The wireless UE according to claim 7, wherein, The sidelink DRX HARQ RTT timer operates based on the resource for the HARQ feedback within the PSSCH.

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