Method and apparatus for control and data channel transmission and reception in wireless communication system

Abstract

A method and apparatus are provided in a wireless communication system. A plurality of physical sidelink shared channels (PSSCHs) are received at a first user equipment (UE) from a second UE on a first plurality of carriers. A plurality of physical sidelink feedback channels (PSFCHs) are transmitted to a second UE on a second plurality of carriers based on a first maximum number of simultaneous PSFCH transmissions in the time slot. Each PSFCH of the plurality of PSFCHs corresponds to a respective PSSCH of the plurality of PSSCHs.

Description

Technical Field

[0001] This disclosure generally relates to wireless communication systems, and more specifically, to methods and apparatus for allocating resources in wireless communication systems. Background Technology

[0002] Fifth-generation (5G) mobile communication technology defines a wide frequency band, enabling high transmission rates and new services. It can be implemented not only in "sub-6GHz" bands such as 3.5 GHz, but also in "above-6GHz" bands, including 28 GHz and 39 GHz, known as millimeter waves (mmWave). Furthermore, to achieve transmission rates fifty times faster than 5G and ultra-low latency one-tenth that of 5G, sixth-generation (6G) mobile communication technology (also known as super 5G systems) can be implemented in terahertz (THz) bands (e.g., the 95 GHz to 3 THz band).

[0003] In the early stages of 5G mobile communication technology development, to support services and meet performance requirements related to enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC), standardization has been underway for the following: beamforming and massive multiple-input multiple-output (MIMO) to mitigate radio wave path loss and increase radio wave transmission distance in mmWave; support for basic parameter sets (e.g., operating multiple subcarrier spacings) for dynamic operation that effectively utilizes mmWave resources and time slot formats; initial access technologies to support multi-beam transmission and broadband; definition and operation of the bandwidth portion (BWP); new channel coding and decoding methods, such as low-density parity-check (LDPC) codes for large data transmissions and polar codes for highly reliable transmission of control information; layer 2 (L2) preprocessing; and network slicing to provide dedicated networks for specific services.

[0004] Given the services that 5G mobile communication technology will support, there has been discussion about improvements and performance enhancements to the initial 5G mobile communication technology, and physical layer standardization has been established for technologies such as: Vehicle-to-Everything (V2X), used to assist autonomous driving determination based on information sent by the vehicle about its location and status, and to enhance user convenience; New Radio Unlicensed (NR-U), designed to comply with the system operation requirements related to various regulations in unlicensed bands; New Radio (NR) User Equipment (UE) power saving; Non-Terrestrial Network (NTN), which is UE-satellite direct communication, used to provide coverage in areas where communication with terrestrial networks is unavailable; and positioning.

[0005] Furthermore, standardization is underway in air interface architecture / protocols for technologies such as: Industrial Internet of Things (IIoT) to support new services through interoperability and convergence with other industries; Integrated Access and Backhaul (IAB) to provide nodes for network service area extension by supporting wireless backhaul links and access links in an integrated manner; mobility enhancements, including conditional handover and Dual Active Protocol Stack (DAPS) handover; and two-step random access to simplify random access procedures (2-step RACH for NR). Standardization is also underway in system architecture / services for: 5G baseline architecture (e.g., service-based architecture or service-based interface) to combine Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies; and Mobile Edge Computing (MEC) for receiving services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, the number of connected devices will increase exponentially, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of connected devices. To this end, new research is planned related to: extended reality (XR) for effectively supporting augmented reality (AR), virtual reality (VR), mixed reality (MR), etc.; improving 5G performance and reducing complexity by leveraging artificial intelligence (AI) and machine learning (ML); AI service support; metaverse service support; and drone communication.

[0007] Furthermore, this development of 5G mobile communication systems will not only serve as the foundation for developing new waveforms for providing terahertz band coverage for 6G mobile communication technologies, multi-antenna transmission technologies (such as full-dimensional MIMO (FD-MIMO), array antennas, and massive MIMO), metamaterial-based lenses and antennas for improving terahertz band signal coverage, high-dimensional spatial multiplexing technologies using orbital angular momentum (OAM), and reconfigurable smart surfaces (RIS), but also as the foundation for developing full-duplex technologies to improve the frequency efficiency of 6G mobile communication technologies and improve system networks, AI-based communication technologies to implement system optimization by leveraging satellites and AI from the design phase and internalizing end-to-end AI support capabilities, and next-generation distributed computing technologies to implement services with complexity levels exceeding UE operational capability limitations by utilizing ultra-high-performance communication and computing resources. Summary of the Invention

[0008] Solution to the problem

[0009] One aspect of this disclosure provides a method and apparatus for allocating resources in a wireless communication system.

[0010] According to an embodiment, a method is provided performed by a first UE in a wireless communication system. A plurality of Physical Side Link Shared Channels (PSSCHs) are received from a second UE on a first plurality of carriers. Based on a first maximum number of simultaneous PSFCH transmissions in a time slot, a plurality of Physical Side Link Feedback Channels (PSFCHs) are transmitted to the second UE on a second plurality of carriers. Each PSFCH in the plurality of PSFCHs corresponds to a corresponding PSSCH in the plurality of PSSCHs.

[0011] According to an embodiment, a method is provided performed by a second UE in a wireless communication system. A plurality of PSSCHs are transmitted to the first UE on a first plurality of carriers. Based on a first maximum number of simultaneous PSFCHs transmitted in a time slot, a plurality of PSFCHs are received from the first UE on a second plurality of carriers. Each PSFCH in the plurality of PSFCHs corresponds to a corresponding PSSCH in the plurality of PSSCHs.

[0012] According to embodiments of this disclosure, a first UE is provided in a wireless communication system. The first UE includes a transceiver and a controller coupled to the transceiver. The controller is configured to receive a plurality of PSSCHs from a second UE on a first plurality of carriers, and to transmit a plurality of PSFCHs to the second UE on a second plurality of carriers based on a first maximum number of simultaneous PSFCHs transmitted in a time slot. Each PSFCH in the plurality of PSFCHs corresponds to a corresponding PSSCH in the plurality of PSSCHs.

[0013] According to an embodiment, a second UE is provided in a wireless communication system. The second UE includes a transceiver and a controller coupled to the transceiver. The controller is configured to transmit a plurality of PSSCHs to the first UE on a first plurality of carriers and to receive a plurality of PSFCHs from the first UE on a second plurality of carriers based on a first maximum number of simultaneous PSFCHs transmitted in a time slot. Each of the plurality of PSFCHs corresponds to a corresponding PSSCH in the plurality of PSSCHs. Attached Figure Description

[0014] The above and other aspects, features and advantages of embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0015] Figure 1 This is a diagram illustrating a system according to an embodiment;

[0016] Figure 2 This is a diagram illustrating a V2X communication method according to an embodiment;

[0017] Figure 3 This is a diagram illustrating the protocol of a V2X UE according to an embodiment;

[0018] Figure 4This is a diagram illustrating an example of a V2X communication protocol according to an embodiment;

[0019] Figure 5 This is a diagram illustrating a V2X communication protocol according to an embodiment;

[0020] Figure 6 This is a diagram illustrating a sidelink (SL) resource pool for V2X communication performed by a V2X UE according to an embodiment;

[0021] Figure 7 This is a diagram illustrating a multiplexing scheme for the SL control channel, SL data channel, and SL feedback channel in the SL resource pool according to an embodiment;

[0022] Figure 8A This is a diagram illustrating an example of time axis resource allocation for the SL feedback channel according to an embodiment;

[0023] Figure 8B This is a diagram illustrating another example of time axis resource allocation for the SL feedback channel according to an embodiment;

[0024] Figure 9A This is a diagram illustrating an example of the resource structure of the SL feedback channel according to an embodiment;

[0025] Figure 9B This is a diagram illustrating another example of the resource structure of the SL feedback channel according to an embodiment;

[0026] Figure 10 This is a diagram illustrating an example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0027] Figure 11 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0028] Figure 12 This is a diagram illustrating another example of time axis resource allocation for the SL feedback channel according to an embodiment;

[0029] Figure 13A This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0030] Figure 13B This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0031] Figure 13C This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0032] Figure 13D This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0033] Figure 13E This is a diagram illustrating an example of calculating the number of bits of feedback information transmitted via the SL feedback channel according to an embodiment;

[0034] Figure 14 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0035] Figure 15 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0036] Figure 16 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0037] Figure 17 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0038] Figure 18 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0039] Figure 19 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0040] Figure 20A This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0041] Figure 20B This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0042] Figure 21A This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0043] Figure 21B This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment;

[0044] Figure 22A This is a flowchart illustrating the operation of a receiving UE for transmitting SL Hybrid Automatic Repeat Request (HARQ) feedback according to an embodiment;

[0045] Figure 22B This is a flowchart illustrating the operation of a receiving UE for SL HARQ feedback transmission according to an embodiment;

[0046] Figure 23 A method for controlling the transmit power of an SL feedback channel according to an embodiment is shown;

[0047] Figure 24 This is a block diagram illustrating the transmission of a UE according to an embodiment;

[0048] Figure 25 This is a block diagram illustrating the receiving UE according to an embodiment;

[0049] Figure 26 This is a block diagram illustrating a base station according to an embodiment;

[0050] Figure 27 This is a diagram illustrating a V2X communication method according to an embodiment;

[0051] Figure 28 This is a diagram illustrating a method by which a UE allocates transmit power for multiple PSFCH transmissions according to an embodiment; and

[0052] Figure 29 This is a diagram illustrating the PSFCH scheduled in a resource pool across multiple carriers according to an embodiment of the present disclosure. Detailed Implementation

[0053] Embodiments of this disclosure are described in detail below with reference to the accompanying drawings. Similar components may be denoted by the same or similar reference numerals, although they are shown in different drawings.

[0054] In describing the embodiments, descriptions relating to technical content known in the relevant art and not directly related to this disclosure will be omitted. This omission of unnecessary descriptions is intended to prevent obscuring the main ideas of this disclosure and to convey them more clearly.

[0055] For the same reason, some elements may be exaggerated, omitted, or shown schematically in the accompanying drawings. Furthermore, the size of each element does not perfectly reflect its actual size.

[0056] The advantages and features of this disclosure, as well as methods of implementing them, will become apparent from the embodiments described in detail below with reference to the accompanying drawings. However, this disclosure is not limited to the embodiments set forth below, but can be implemented in a variety of different forms. The following embodiments are provided only to fully disclose this disclosure and to inform those skilled in the art of its scope, and this disclosure is defined only by the scope of the appended claims. Throughout the specification, the same or similar reference numerals indicate the same or similar elements.

[0057] Here, each box in the flowchart illustration, and combinations of boxes in the flowchart illustration, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more flowchart boxes. These computer program instructions can also be stored in a computer-usable or computer-readable storage medium that can instruct the computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-usable or computer-readable storage medium produce an article of writing including instruction means for implementing the functions specified in one or more flowchart boxes. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus, thereby producing a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowchart boxes.

[0058] Furthermore, each box in the flowchart diagram may represent a module, segment, or section of code, which includes one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions mentioned in the boxes may occur out of order. For example, depending on the functions involved, two boxes shown consecutively may actually execute substantially concurrently, or the boxes may sometimes execute in reverse order.

[0059] As used in embodiments of this disclosure, "unit" refers to a software or hardware element that performs a predetermined function, such as a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC). However, "unit" is not always limited to software or hardware. A "unit" can be configured to be stored in addressable storage media or to execute one or more processors. Thus, a "unit" includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and parameters. Elements and functions provided by a "unit" can be combined into a smaller number of elements or "units," or divided into a larger number of elements or "units." Furthermore, elements and "units" can be implemented as one or more central processing units (CPUs) within a playback device or secure multimedia card. Additionally, a "unit" in the embodiments may include one or more processors.

[0060] The following detailed description of embodiments of this disclosure is primarily directed to NR as a radio access network and packet core as a core network in the 5G mobile communication standard specified by the 3rd Generation Partnership Project (3GPP), which is the mobile communications standardization group. However, based on the determination of those skilled in the art, the main ideas of this disclosure can be applied to other communication systems with similar backgrounds with some modifications without significantly departing from the scope of this disclosure.

[0061] In the following description, for ease of description, some terms and names defined in the 3GPP Long Term Evolution (LTE) standards (standards for 5G, NR, LTE or similar systems) may be used. However, this disclosure is not limited to these terms and names and can be applied in the same manner to systems conforming to other standards.

[0062] In the following description, for ease of description, terms for identifying access nodes, referring to network entities, referring to messages, referring to interfaces between network entities, referring to various types of identification information, etc., are used illustratively. Therefore, this disclosure is not limited to the terminology used herein, and other terms that refer to subjects with equivalent technical meanings may be used.

[0063] In the following description, a base station is an entity that allocates resources to terminals and can be at least one of a gNode B, eNode B, Node B, base station (BS), radio access unit, BS controller, and nodes on a network. Terminals can include UEs, mobile stations (MS), cellular phones, smartphones, computers, or multimedia systems capable of performing communication functions. Of course, BSs are not limited to the examples above. Here, "downlink (DL)" refers to the radio link through which the base station transmits signals to the terminal, and "uplink (UL)" refers to the radio link through which the terminal transmits signals to the base station. To meet the increased demand for wireless data traffic since the deployment of 4G communication systems, efforts have been made to develop improved 5G communication systems (NR). 5G communication systems have been designed to support ultra-high frequency (mmWave) bands (e.g., the 28 GHz band) to achieve higher data rates. To reduce radio wave propagation loss and increase transmission distance in the ultra-high frequency band, beamforming, massive MIMO, FD-MIMO, array antennas, analog beamforming, and massive MIMO technologies are being discussed in 5G communication systems. Furthermore, unlike LTE, 5G communication systems support various subcarrier spacings including 15kHz, 30kHz, 60kHz, and 120kHz. The physical control channel uses polarization coding, and the physical data channel uses LDPC. Additionally, Cyclic Prefix (CP)-Orthogonal Frequency Division Multiplexing (OFDM) and Discrete Fourier Transform-Extended (DFT-S)-OFDM are also used as waveforms for UL transmission. While LTE supports HARQ retransmission on a transport block (TB) basis, 5G can additionally support HARQ retransmission based on bundled code block groups (CBGs) comprising multiple code blocks (CBs).

[0064] In addition, in 5G communication systems, technologies for improving system networks are being developed based on evolved small cells, advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multipoint (CoMP), and receiver interference cancellation.

[0065] The Internet, as a human-centric network of connections where humans generate and consume information, is now evolving into the Internet of Things (IoT), in which distributed entities (such as things) exchange and process information without human intervention. The Internet of Everything (IoE) has emerged, a combination of IoT technologies and big data processing technologies connected to cloud servers and the like. Because IoT implementation already requires technological elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology, and security technology, sensor networks, machine-to-machine (M2M) communication, and machine-type communication (MTC) have recently been researched. Such an IoT environment can provide intelligent Internet of Things (IT) services, creating new value for human life by collecting and analyzing data generated in connected things. Through the integration and combination of existing information technology (IT) with various industrial applications, IoT can be applied to a wide range of fields, including smart homes, smart buildings, smart cities, smart or connected cars, smart grids, healthcare, smart appliances, and advanced medical services.

[0066] Consistent with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, MTC, and M2M communication are implemented using beamforming, MIMO, and array antenna technologies, which are 5G communication technologies. Cloud radio access networks (RAN), as an application of the aforementioned big data processing technologies, can also be considered an example of the convergence of 5G and IoT technologies. As mentioned above, multiple services can be provided to users in a communication system, and to provide such multiple services to users, a method and apparatus for providing each service within the same time period based on its characteristics are required. Various services to be provided in 5G communication systems are being investigated, one of which is a service that meets the requirements of low latency and high reliability.

[0067] In the context of vehicle-to-everything (V2X) communication, LTE-based V2X has been standardized in 3GPP Rel-14 and Rel-15 based on the D2D communication architecture, and efforts are currently underway to develop 5G NR-based V2X. NR V2X is scheduled to support unicast, multicast (or multicast) and broadcast communication between UEs. Furthermore, unlike LTE V2X, which is designed to send and receive basic safety information necessary for vehicles to travel on the road, NR V2X aims to provide more advanced services such as platooning, advanced driver assistance, extended sensors, or remote driving.

[0068] An NR V2X receiving UE can send SL control information and data information to another NR V2X receiving UE. An NR V2X receiving UE that has received this information can send an acknowledgment (ACK) or a negative acknowledgment (NACK) to an NR V2X sending UE for the received SL data information. The ACK / NACK message can be referred to as the SL Feedback Control Message (SFCI). The SFCI can be sent through the physical layer's PSFCH.

[0069] Simultaneously, the NR V2X transmitting UE can transmit an SL reference signal to allow the NR V2X receiving UE to obtain information about the SL channel state. In this case, the SL reference signal can be a demodulation reference signal (DMRS) used by the NR V2X receiving UE to perform channel estimation or a channel state information reference signal (CSI-RS) used to obtain channel state information (CSI). When using CSI-RS, it can be transmitted using time / frequency / code resources different from those of the DMRS. The NR V2X receiving UE, which has already obtained the CSI about the SL channel through the DMRS or CSI-RS transmitted by the NR V2X transmitting UE, can report the obtained CSI to the NR V2X transmitting UE. In this case, the CSI can be the aforementioned SFCI and can be transmitted through the SL feedback channel. As another example, HARQ-ACK / NACK information and CSI reporting information can be multiplexed and transmitted simultaneously through the SL feedback channel.

[0070] Embodiments are proposed to support the above scenario, and the embodiments will be used to provide a method and apparatus for transmitting or receiving SL feedback channels by an NR V2X UE.

[0071] This disclosure relates to a method for allocating resources for a feedback channel in a wireless communication system, and more particularly, to a method and apparatus for allocating resources for transmitting and receiving SL feedback channels between UEs.

[0072] The embodiments provide a method and apparatus for allocating resources for UEs to transmit and receive SL feedback channels in a wireless communication environment where UEs have SL feedback channels.

[0073] For ease of description, the terms and names defined in the 5GS and NR standards, which are existing communication standards specified by the 3GPP group, will be used herein. However, this disclosure is not limited to these terms and names and can be applied in the same manner to systems conforming to other standards. For example, this disclosure can be applied to 3GPP 5GS / NR (5G mobile communication standard).

[0074] Figure 1 This is a diagram illustrating a system according to an embodiment.

[0075] Figure 1 Part (a) shows an example of all V2X UEs (UE-1 and UE-2) located within the coverage of the base station (gNB / eNB / RSU).

[0076] All V2X UEs (UE-1 and UE-2) can receive data and control information from the BS (gNB / eNB / RSU) via DL, or transmit data and control information to the base station via UL. In this case, the data and control information can be for V2X communication. Alternatively, the data and control information can be for conventional cellular communication. Additionally, V2X UEs (UE-1 and UE-2) can send / receive data and control information for V2X communication via SL.

[0077] Figure 1 Part (b) shows an example of a V2X UE where UE-1 is located within the coverage of the BS (gNB / eNB / RSU) and UE-2 is located outside the coverage of the base station (gNB / eNB / RSU). Figure 1 The example of part (b) can be called the example of partial coverage.

[0078] UE-1 located within the coverage of BS (gNB / eNB / RSU) can receive data and control information from BS (gNB / eNB / RSU) via DL, or send data and control information to BS (gNB / eNB / RSU) via UL.

[0079] UE-2 located outside the coverage of BS (gNB / eNB / RSU) cannot receive data and control information from BS (gNB / eNB / RSU) via DL, and cannot send data and control information to BS (gNB / eNB / RSU) via UL.

[0080] UE-2 can send data and control information for V2X communication to or receive data and control information from UE-1 via SL.

[0081] Figure 1 Section (c) shows an example of all V2X UEs (UE-1 and UE-2) located outside the coverage of the base station (gNB / eNB / RSU).

[0082] Therefore, UE-1 and UE-2 cannot receive data and control information from the BS (gNB / eNB / RSU) via DL, and cannot send data and control information to the BS (gNB / eNB / RSU) via UL.

[0083] UE-1 and UE-2 can send or receive data and control information for V2X communication to or from each other via SL.

[0084] Figure 1 Part (d) is an example of performing V2X communication between UEs located in different cells. Specifically, Figure 1 Part (d) illustrates a scenario where the V2X transmitting UE and the V2X receiving UE are connected to different BSs (gNB / eNB / RSU) (Radio Resource Control (RRC) connected state) or camped on different BSs (RRC connected released state, i.e., RRC idle state) (inter-cell V2X communication). In this case, UE-1 can be a V2X transmitting UE, and UE-2 can be a V2X receiving UE. Alternatively, UE-1 can be a V2X receiving UE, and UE-2 can be a V2X transmitting UE. UE-1 can receive V2X Dedicated System Information Blocks (SIBs) from the BS (gNB / eNB / RSU) to which UE-1 is connected (or on which UE-1 camps), and UE-2 can receive V2X Dedicated SIBs from another base station to which UE-2 is connected (or on which UE-2 camps). In this case, the V2X Dedicated SIB information received by UE-1 and the V2X Dedicated SIB information received by UE-2 can be different from each other. Therefore, it is necessary to match information to perform V2X communication between UEs located in different cells.

[0085] exist Figure 1 For ease of description, a V2X system comprising two UEs (UE-1 and UE-2) is shown in this document; however, this disclosure is not limited to this, and multiple UEs may participate in a V2X system. Furthermore, the UL and DL between the BS (gNB / eNB / RSU) and the V2X UEs (UE-1 and UE-2) may be referred to as the Uu interface, and the SL between the V2X UEs (UE-1 and UE-2) may be referred to as the PC5 interface. Therefore, these can be used interchangeably herein.

[0086] Here, "vehicle" can mean a vehicle supporting vehicle-to-vehicle (V2V) communication, a vehicle or pedestrian mobile phone supporting vehicle-to-pedestrian (V2P) communication, a vehicle supporting vehicle-to-network (V2N) communication, or a vehicle supporting vehicle-to-infrastructure (V2I) communication. Furthermore, "UE" can be a roadside unit (RSU) equipped with UE functionality, an RSU equipped with BS functionality, or an RSU equipped with a portion of BS functionality and a portion of UE functionality, etc.

[0087] Furthermore, a BS can be predefined as a BS that supports both V2X communication and general cellular communication, or a BS that only supports V2X communication. In this case, the BS can be a 5G BS (gNB), a 4G BS (eNB), or an RSU. Therefore, unless otherwise described, BS and RSU can be used with the same concept, and thus, BS and RSU can be used interchangeably.

[0088] Figure 2 This is a diagram illustrating a V2X communication method according to an embodiment.

[0089] As in Figure 2 As shown in part (a), the transmitting (TX) UE and the receiving (RX) UE can perform one-to-one communication, which can be referred to as unicast communication.

[0090] like Figure 2 As shown in section (b), the TX UE and RX UE can perform one-to-many communication. This can be referred to as multicast or multicast communication.

[0091] Figure 2 Part (b) shows that UE-1, UE-2, and UE-3 form a group (Group A) to perform multicast communication, and UE-4, UE-5, UE-6, and UE-7 form another group (Group B) to perform multicast communication. Each UE can perform multicast communication only within its own group and can communicate with UEs in different groups via unicast, multicast, or broadcast communication. Figure 2 Part (b) shows the formation of two groups, but this disclosure is not limited thereto and more groups can be formed.

[0092] V2X UEs can perform broadcast communication. Broadcast communication can mean that all V2X UEs can receive data and control information sent by the V2X sending UE via SL. For example, assuming... Figure 2 When UE-1 in part (b) is the transmitting UE used for broadcasting, all UEs (UE-2, UE-3, UE-4, UE-5, UE-6 and UE-7) can receive data and control information transmitted by UE-1.

[0093] According to the embodiments, SL broadcast, multicast, and unicast communication methods can be supported in coverage, out-of-coverage, and partial coverage scenarios.

[0094] Unlike LTE V2X systems, NR V2X systems can support both unicast data transmission from a vehicle UE to a single specific UE and multicast data transmission from a vehicle UE to multiple specific UEs. For example, these unicast and multicast techniques can be useful when considering service scenarios such as platooning, a technique used to connect two or more vehicles via a network to allow vehicles to travel in groups. Specifically, unicast communication may be required for the purpose of a leader UE controlling a specific UE within a group connected via platooning, while multicast communication may be needed for the purpose of simultaneously controlling a group comprising a specific number of UEs.

[0095] Resource allocation in a V2X system according to an embodiment can be performed using the following methods.

[0096] -Mode 1 Resource Allocation

[0097] Mode 1 resource allocation can mean a resource allocation method scheduled by the BS. More specifically, in Mode 1 resource allocation, the base station can allocate resources for SL transmission to UEs with RRC connections in a dedicated scheduling scheme. The scheduled resource allocation method may be effective for interference management and resource pool management (dynamic allocation and / or semi-persistent transmission) because the base station can manage SL resources. If there is data to be sent to other UEs(s), the RRC connection mode UE can send information to the base station notifying the base station of the existence of data to be sent to other UEs(s) ...

[0098] -Mode 2 Resource Allocation

[0099] Mode 2 resource allocation can mean a method where the SL transmitting UE autonomously selects resources (UE autonomous resource selection). More specifically, Mode 2 resource allocation is a method in which the base station provides the UE with an SL transmit / receive resource pool for V2X via system information or RRC messages (e.g., RRCReconfiguration messages or PC5-RRC messages), and the transmitting UE selects the resource pool and resources according to defined rules. In the example above, the base station provides configuration information about the SL transmit / receive resource pool, and therefore, Mode 2 resource allocation is applicable when the V2X transmitting / receive UE is within the coverage of the BS. When the V2X transmitting / receive UE is outside the coverage of the BS, the V2X transmitting / receive UE can perform Mode 2 resource allocation operations within a pre-configured transmit / receive resource pool. UE autonomous resource selection methods can include area mapping, sense-based resource selection, random selection, etc.

[0100] - Additionally, even though the V2X transmitting / receiving UE is within the coverage of the base station, it is not necessary to perform resource allocation or resource selection or scheduling in the UE autonomous resource selection mode. In this case, the UE can perform V2X SL communication through the pre-configured SL transmitting / receiving resource pool.

[0101] Figure 3 This is a diagram illustrating the protocol of a V2X UE according to an embodiment.

[0102] The application layer of UE-A and UE-B can perform service discovery. In this case, service discovery can include the discovery of V2X communication schemes (e.g., unicast, multicast, or broadcast) performed by each UE. Therefore, in Figure 3 In this context, it can be assumed that UE-A and UE-B have already identified the unicast communication scheme through the service discovery process performed at the application layer. The NR V2X UE can obtain information about the source ID and destination ID of the NR V2X unicast communication during the aforementioned service discovery process.

[0103] If the service discovery process is complete, then Figure 3 The PC5 signaling protocol layer shown can execute direct link establishment procedures between UEs. In this case, security configuration information for direct communication between UEs can be sent or received.

[0104] If the direct link establishment procedure is completed, then... Figure 3 The PC5-RRC establishment procedure between UEs is executed in the PC5-RRC layer. In this case, information about the capabilities of UE-A and UE-B can be exchanged, as well as access layer (AS) parameter information for unicast communication.

[0105] Once the PC5-RRC configuration procedure is completed, UE-A and UE-B can perform unicast communication.

[0106] Although unicast communication has been described above, it can be similarly applied to multicast communication. For example, when UE-A, UE-B, and UE-C perform multicast communication, as described above, service discovery, direct link establishment, and PC5-RRC establishment procedures between UE-A and UE-B can be performed between UE-B and UE-C, and between UE-A and UE-C.

[0107] More specifically, the NR V2X UE can obtain information about the source ID and destination ID used for NR V2X multicast communication during the service discovery process described above. If the service discovery process is complete, then... Figure 3 The PC5 signaling protocol layer shown can execute direct link establishment procedures between UEs. In this case, security configuration information for direct communication between UEs can be sent or received.

[0108] If the direct link establishment procedure is completed, then... Figure 3 The PC5-RRC establishment procedure between UEs is executed in the PC5-RRC layer. In this case, information about the capabilities of UE-A, UE-B, and UE-C can be exchanged, as well as AS layer parameter information for multicast communication. However, when there are three or more UEs, significant signaling overhead and communication latency can occur when exchanging information about their capabilities and AS layer parameter information. Therefore, in the case of multicast communication, if the described direct link establishment procedure is completed, the PC5-RRC establishment procedure between UEs can be omitted.

[0109] When the PC5-RRC establishment procedure is completed (or when the direct link establishment procedure is completed without omitting the PC5-RRC establishment procedure), UE-A, UE-B, and UE-C can perform multicast communication.

[0110] Figure 4 This is a diagram illustrating an example of a V2X communication procedure according to an embodiment.

[0111] More specifically, Figure 4 It shows the basis Figure 2 The V2X communication protocol for Mode 1 resource allocation is described in [the document / section]. Figure 4In this context, the gNB can configure parameters for V2X communication to the V2X UE in the cell via system information. For example, the gNB can configure information about resource pools that can perform V2X communication in its own cell. In this case, a resource pool can refer to a transmit resource pool for V2X transmission or a receive resource pool for V2X reception. Additionally, a resource pool can refer to an SL control information resource pool for transmitting or receiving V2X control information, an SL data information resource pool for transmitting or receiving V2X data information, or an SL feedback information resource pool for transmitting or receiving V2X feedback information.

[0112] A V2X UE can receive configuration information about one or more resource pools from a gNB. The gNB can configure unicast, multicast, and broadcast communications to be performed in different resource pools using system information. For example, resource pool 1 can be used for unicast communications, resource pool 2 for multicast communications, and resource pool 3 for broadcast communications. As another example, a BS can configure unicast, multicast, and broadcast communications to be performed in the same resource pool. The resource pool information configured by the gNB can include at least one of the following:

[0113] - Regarding the timeline information of the resource pool in which physical SL control channels (PSCCH) and (PSSCH) can be transmitted: Specifically, this information may include the index and time period of the time slot in which PSCCH and PSSCH can be transmitted, the index of the time slot in which PSCCH and PSSCH can be transmitted, the index and time period of the symbol in the corresponding time slot, etc.

[0114] - Regarding frequency axis information of resource pools in which PSCCH and PSSCH can be transmitted: Specifically, this information may include the index of resource blocks in which PSCCH and PSSCH can be transmitted, or the index of sub-channels comprising two or more resource blocks.

[0115] Information regarding whether to perform SL HARQ-ACK can be included in the resource pool configuration information.

[0116] • For the SL HARQ-ACK operation, at least one of the following information may be included.

[0117] ○ Maximum number of retransmissions

[0118] ○HARQ-ACK timing: This refers to the time interval from the point when the V2X receives the UE's SL control and data information to the point when the V2X receives the UE's HARQ-ACK / NACK information. In this case, the time unit can be a time slot or one or more OFDM symbols.

[0119] ○-Physical Feedback Channel (PSFCH) Format: When operating with two or more PSFCH formats, one PSFCH format can be used to send HARQ-ACK / NACK information including 1 or 2 bits. Another PSFCH format can be used to send HARQ-ACK / NACK information including 3 or more bits. When sending the aforementioned HARQ-ACK / NACK information via PSFCH, each of the ACK and NACK information can be sent through that PSFCH. In this case, when decoding of the PSFCH sent by the NR V2X transmitting UE is successfully performed, the NR V2X receiving UE can send ACK through the PSFCH. If decoding fails, NACK can be sent through the PSFCH. As another example, when decoding of the PSFCH sent by the NR V2X transmitting UE is successfully performed, the NR V2X receiving UE may not send ACK, but may only send NACK through the PSFCH if decoding fails.

[0120] ○ The time / frequency / code resources or resource set that constitute the PSFCH: Time resources may include the slot index or symbol index and period used for PSFCH transmission. Frequency resources may include the start and end points (or the start point and length of frequency resources) of a subchannel containing two or more consecutive blocks or frequency resource blocks (RBs) for transmitting the PSFCH.

[0121] • When not operating SL HARQ-ACK, information related to the SL feedback channel may not be included.

[0122] Information regarding whether to perform blind retransmission can be included in the resource pool configuration information.

[0123] • Unlike HARQ-ACK / NACK-based retransmissions, blind retransmissions mean that the NR transmitting UE does not receive feedback information about ACK or NACK from the NR receiving UE; instead, the NR transmitting UE repeatedly performs the transmission. When blind retransmissions are performed, the number of blind retransmissions can be included in the resource pool information. For example, when the number of blind retransmissions is set to 4, the NR transmitting UE can always send the same information four times when sending PSCCH / PSSCH to the NR receiving UE. In this case, the Redundancy Version (RV) value can be included in the SL control information (SCI) sent via PSCCH.

[0124] - Information about the DMRS mode that can be used in PSSCHs sent in the corresponding resource pool.

[0125] • Depending on the UE's speed, the DMRS modes available in the PSSCH can vary. For example, at high speeds, it's necessary to increase the number of OFDM symbols used for DMRS transmission on the timeline to enhance channel estimation accuracy. Conversely, since channel estimation accuracy can be guaranteed even with a small number of DMRS symbols at low UE speeds, it's necessary to reduce the number of OFDM symbols used for DMRS transmission on the timeline to reduce DMRS overhead. Therefore, information about resource pools can include information about the DMRS modes available in the corresponding resource pool. In this case, two or more DMRS modes can be configured in one resource pool, and the NR V2X transmitting UE can select and use one of the configured DMRS modes based on its own speed. Furthermore, the NR V2X transmitting UE can send information about its selected DMRS mode to the NR V2X receiving UE via the SCI of the PSSCH. The NR V2X receiving UE can receive this information and obtain the DMRS mode information, perform channel estimation on the PSSCH, and perform demodulation and decoding processes to obtain SL data information.

[0126] - Whether to operate SL CSI-RS

[0127] • When operating SL CSI-RS, at least one of the following pieces of information may be included.

[0128] ○CSI-RS transmission start time: This can mean the start time at which the V2X transmitting UE needs to send CSI-RS to the V2X receiving UE. The start time can refer to the index of the time slot for transmitting CSI-RS, the index of the symbol for transmitting CSI-RS, or both the time slot index and the symbol index.

[0129] ○CSI Report Timing: This refers to the time interval from the point in time when the V2X receiving UE receives the CSI-RS from the V2X sending UE (i.e., the received slot index or the symbol index in the received slot) to the point in time when the V2X receiving UE sends the CSI report to the V2X sending UE (i.e., the slot index of the sent CSI report or the symbol index in the sent slot index). In this case, the time unit can be a slot or one or more OFDM symbols.

[0130] • This information may be omitted when SL CSI-RS is not in operation.

[0131] ○ Parameters used for SL transmit power control

[0132] The above information has been illustrated as being included in the resource pool configuration used for V2X communication, but this disclosure is not limited thereto. In other words, the above information can be configured independently of the resource pool configuration for either a V2X sending UE or a V2X receiving UE.

[0133] like Figure 4 As shown, when data to be sent to a V2X RX-UE is generated in a V2X TX-UE, the V2X transmitting UE can use a SR and / or BSR to request SL resources from the gNB to be sent to the V2X receiving UE. The gNB, having received the BSR, can recognize that the UE has data for SL transmission and determine the resources required for SL transmission based on the BSR.

[0134] The gNB can send a SL scheduling authorization to the V2X UE, which includes at least one of resource information for SL data transmission and resource information for SCI transmission. The SL scheduling authorization is information used to authorize dynamic scheduling in the SL and can be DL control information (DCI) transmitted on the physical DL control channel (PDCCH). When the base station is an NR base station, the SL scheduling authorization may include information indicating the BWP for performing SL transmission and the carrier indicator field (CIF) or carrier frequency indicator for performing SL transmission; when the base station is an LTE base station, it may only include the CIF. Furthermore, the SL scheduling authorization may also include resource allocation information related to the PSFCH for transmitting feedback information (A / N information) for SL data. When the SL transmission is multicast, the resource allocation information may include information for allocating multiple PSFCH resources for multiple UEs in the group. Additionally, the resource allocation information related to the feedback information may be information indicating at least one of a set of multiple feedback information resource candidates configured via higher-layer signaling.

[0135] A V2X TX-UE that has received SL scheduling authorization sends a SCI (Schedule Instruction) to a V2X RX-UE via PSCCH to schedule SL data according to the SL scheduling authorization, and transmits SL data via PSSCH. The SCI may include at least one of the following: resource allocation information for SL data transmission; modulation and coding scheme (MCS) information applied to SL data; group destination ID information; source ID information; unicast destination ID information; power control information for SL power control; timing advance (TA) information; DMRS configuration information for SL transmission; and packet retransmission related information (e.g., the number of packet retransmissions, resource allocation related information during packet retransmission, RV, and HARQ process IDs). Furthermore, the SCI may also include information indicating resources for transmitting feedback information (A / N information) for SL data.

[0136] A V2X RX-UE that has already received SCI receives SL data. Subsequently, the V2X RX-UE sends ACK / NACK information on the PSFCH to the V2X UE indicating whether the decoding of the SL data was successful or failed. Feedback information transmission for SL can be applied to unicast or multicast transmissions, but broadcast transmission is not excluded. If the SL transmission corresponds to a multicast transmission, each UE that has received multicast data can send feedback information using different PSFCH resources. Alternatively, each UE that has received multicast data can send feedback information using the same PSFCH resources, and in this case, only NACK information is fed back (i.e., UEs that have received data do not perform feedback if ACK is received). In this case, PSFCH resources can include not only resources distinguished in the time and / or frequency domains, but also resources distinguished using codes such as scrambling codes or orthogonal overlay codes, and resources distinguished using different sequences (and cyclic shifts applied to the sequences).

[0137] Figure 4 Assuming the V2X TX-UE is connected to the gNB via a UL connection (i.e., RRC connected state), and both the V2X TX-UE and V2X RX-UE are within the gNB's coverage area, when the V2X transmitting UE is not connected to the gNB via a UL connection (i.e., RRC idle state), the V2X TX-UE can execute the random access procedure for configuring the UL connection with the gNB. Furthermore, in scenarios where the V2X TX-UE is within the gNB's coverage area and the V2X RX-UE is outside the gNB's coverage area, the V2X RX-UE can be pre-configured with and use the aforementioned information for V2X communication. Simultaneously, the V2X TX-UE can be configured with information from the gNB for V2X communication, such as... Figure 4 As shown.

[0138] When both the V2X TX-UE and V2X RX-UE are outside the coverage of the gNB, the V2X TX-UE and V2X RX-UE can be pre-configured with and use the aforementioned information for V2X communication. In this case, being pre-configured can mean using the values ​​stored in the UE when it is released. In another sense, when the V2X TX-UE or RX-UE has already accessed the gNB and has already obtained information about V2X communication through RRC configuration or has experience obtaining information about V2X communication through the base station's system information, it can mean the most recently obtained information.

[0139] Additionally, it can be assumed that the V2X TX-UE has already passed the SR / BSR before sending it to the gNB. Figure 3The procedures described in the document complete the service discovery, direct link establishment procedures, and PC5 RRC configuration with V2X RX-UE.

[0140] Figure 5 This is a diagram illustrating another V2X communication procedure according to an embodiment.

[0141] More specifically, Figure 5 It shows the basis Figure 2 The V2X communication protocol for mode 2 resource allocation is described in [the document / section]. Figure 5 In this context, the gNB can send / receive UE configuration parameters for V2X communication to / from the V2X network within the cell via system information. In this case, the parameters may include... Figure 4 At least one of the parameter information shown.

[0142] like Figure 5 As shown, when generating data to be sent from a V2X TX-UE to a V2X RX-UE, the V2X TX-UE can send an SCI to the V2X RX-UE via PSCCH and send SL data via PSSCH. The SCI may include at least one of the following: resource allocation information for SL data transmission, MCS information applied to the SL data, group destination ID information, source ID information, unicast destination ID information, power control information for SL power control, timing advance information, DMRS configuration information for SL transmission, and packet retransmission related information (e.g., the number of packet retransmissions, resource allocation related information during packet retransmission, RV and HARQ process IDs). Furthermore, the SCI may also include information indicating resources for sending feedback information (A / N information) for the SL data.

[0143] A V2X RX-UE that has received SCI can receive SL data. Subsequently, the V2X RX-UE can send ACK / NACK information on the PSFCH to the V2X TX-UE indicating whether the decoding of the SL data was successful or failed. Feedback information transmission for SL can be applied to unicast or multicast transmissions, but broadcast transmission is not excluded. If the SL transmission corresponds to a multicast transmission, each UE that has received multicast data can send feedback information using different PSFCH resources. Alternatively, each UE that has received multicast data can send feedback information using the same PSFCH resources, and in this case, only NACK information is fed back (i.e., the UE that has received data does not perform feedback when determining ACK). In this case, PSFCH resources can include not only resources distinguished in the time and / or frequency domains, but also resources distinguished using codes such as scrambling codes or orthogonal overlay codes, and resources distinguished using different sequences (and cyclic shifts applied to the sequences).

[0144] exist Figure 5 In this scenario, it can be assumed that all V2X transmitting / receiving UEs are within the coverage area of ​​the gNB. Even when all V2X transmitting / receiving UEs are outside the coverage area of ​​the gNB, the following can still be applied. Figure 5 Example. In this case, the V2X transmitting / receiving UE can be pre-configured with the aforementioned information for V2X communication. Furthermore, even in scenarios where one of the V2X transmitting / receiving UEs is within the gNB's coverage area and the remaining UEs are outside the gNB's coverage area, this can still be applied. Figure 5 Example. In this scenario, a UE within the gNB's coverage area can be configured with information for V2X communication by the gNB, and a UE outside the gNB's coverage area can be pre-configured with information for V2X communication. In this example, "information for V2X communication" can be interpreted as information about at least one of the parameters used for V2X communication, as described above. Figure 4 As described above. Additionally, in the example, when pre-configured, it can mean using the value stored in the UE when the UE is released. In another sense, when a V2X TX-UE or V2X RX-UE has already accessed the gNB and obtained information about V2X communication through RRC configuration, or has experience obtaining information about V2X communication through system information, it can mean the most recently obtained information.

[0145] It can be assumed that the V2X TX-UE has already passed the PSCCH / PSSCH before the V2X sending UE sends it to the V2X RX-UE. Figure 3 The procedures described in the document complete the service discovery, direct link establishment procedures, and PC5 RRC configuration with V2X RX-UE.

[0146] Despite Figure 5 The text describes unicast communication involving only one V2X RX-UE, but... Figure 5 The same example can be applied to multicast and broadcast communications in which there are two or more V2X RX-UEs.

[0147] Figure 6 This is a diagram illustrating an SL resource pool for V2X communication performed by a V2X UE according to an embodiment.

[0148] Specifically, Figure 6The SL resource pool may include K time slots on the time axis and M resource blocks on the frequency axis. A time slot usually consists of 14 OFDM symbols, but it is not limited thereto. In other words, a time slot constituting the SL resource pool may be less than 14 OFDM symbols. In addition, among the K time slots constituting the SL resource pool, each time slot may include the same number of OFDM symbols (i.e., each of the K time slots includes L symbols), or each time slot may include a different number of OFDM symbols. A resource block may include 12 subcarriers.

[0149] The K time slots may be physically continuous or logically continuous on the time axis (if the time slots are logically continuous, the time slots may be physically discontinuous). Similarly, the M resource blocks may be physically continuous or logically continuous on the frequency axis (if the blocks are logically continuous, the blocks may be physically discontinuous).

[0150] The V2X transmitting UE may use Figure 6 the SL resource pool to transmit SL control information, data information, or feedback information. In addition, the V2X receiving UE may use Figure 6 the SL resource pool to receive SL control information or data information and transmit SL feedback information.

[0151] Figure 7 is a diagram showing a multiplexing scheme of an SL control channel, an SL data channel, and an SL feedback channel in an SL resource pool according to an embodiment.

[0152] Figure 7 shows that the PSCCH is multiplexed with the PSSCH on the time axis and the frequency axis (i.e., time division multiplexing (TDM) and frequency division multiplexing (FDM)). In this case, the PSCCH and the PSSCH may include different numbers of resource blocks on the frequency axis. In other words, as Figure 7 shown, the PSCCH may include N1 resource blocks on the frequency axis, and the PSSCH may include M resource blocks. In this case, N1 may be less than M (N1 < M). However, the case where the PSCCH and the PSSCH include the same number of resource blocks (M RBs) on the frequency axis, or the case where the number of resource blocks of the PSCCH is greater than the number of resource blocks of the PSSCH (i.e., N1 > M) may not be excluded.

[0153] In addition, as Figure 7As shown, the PSCCH and PSSCH are frequency-division multiplexed in K1 OFDM symbols on the time axis, and in the remaining K2 symbols, only the PSSCH can be transmitted without transmitting the PSCCH. In other words, the PSCCH can include N1 frequency blocks on the frequency axis and K1 OFDM symbols on the time axis. The PSSCH can include N2 frequency blocks with a length of K1 OFDM symbols and can be frequency-division multiplexed with the PSCCH. Additionally, for the length of K2 OFDM symbols, the PSSCH can include M frequency blocks that are not frequency-division multiplexed with the PSCCH. In this case, the sum of N2 and N1 can be equal to or different from M.

[0154] Figure 7 It is shown that the N1 frequency blocks constituting the PSCCH and the (M - N2) frequency blocks constituting the PSSCH are physically continuous, but they may not be physically continuous (i.e., they are logically continuous but not physically continuous). The values of K1 and K2 can be equal to or different from each other, and when the values of K1 and K2 are different from each other, K1 > K2 or K1 < K2. The V2X transmitting UE can include the time / frequency allocation information of the PSSCH in the SL control information transmitted through the PSCCH and transmit this information. After receiving and decoding the PSCCH, the V2X receiving UE can obtain the time / frequency allocation information of the PSSCH and decode the PSSCH. Although Figure 7 It is shown that the K2 symbols constituting the PSSCH are physically located continuously after the K1 symbols constituting the PSCCH, but these symbols may not be physically continuous (i.e., they may be logically continuous but not physically continuous).

[0155] Figure 7This illustrates the case where the PSFCH exists within an SL resource comprising K OFDM symbols. In this scenario, a timeslot may include, on the time axis, K1 symbols of PSCCH, K2 symbols of PSSCH (when only symbols not involved in FDM with the PSCCH are considered; if FDM with the PSCCH is considered, then the PSSCH consists of K1+K2 symbols), a protection symbol (GAP), a PSCCHK3 symbol, and a protection symbol GAP. In other words, K1+K2+Protection Symbol 1+K3+Protection Symbol 2=K. In this case, Protection Symbol 1 and Protection Symbol 2 can be one OFDM symbol or two or more OFDM symbols. Protection Symbol 1 may be required for the transition between transmission and reception so that the V2X transmitting UE can transmit the PSCCH and PSSCH and receive the PSFCH. Conversely, from the perspective of the V2X receiving UE, Protection Symbol 1 may be required for the transition between reception and transmission so that the V2X receiving UE can receive the PSCCH and PSSCH and transmit the PSFCH. Similarly, protection symbol 2 might be required for the transition between receiving and transmitting, so that the V2X transmitting UE receives the PSFCH from the V2X receiving UE and transmits the PSCCH and PSSCH in the next SL resource. Conversely, from the perspective of the V2X receiving UE, protection symbol 2 might be required for the transition between transmitting and receiving, so that the V2X receiving UE sends the PSFCH to the V2X transmitting UE and receives the PSCCH and PSSCH in the next SL resource.

[0156] One of the protection symbols 1 and 2 can be 0. For example, when a V2X transmitting UE receives PSFCH and then receives PSCCH and PSSCH from another UE in the next SL resource, no conversion between receiving and transmitting is required, and therefore the number of protection symbols 2 can be 0. Additionally, it is not excluded that at least one of K1, K2, and K3 is 0.

[0157] Although the frequency resource block size of PSFCH is shown as... Figure 7 The frequency resource block size of the PSSCH is the same as that of the PSCCH and PSSCH (i.e., M RBs), but the resource block size of the PSFCH on the frequency axis can be the same as or different from that of the PSCCH and PSSCH. After decoding the PSSCH, the V2X receiving UE can include the success result (i.e., ACK / NACK information) in the PSFCH and send it to the V2X sending UE.

[0158] In the example above, the time and frequency resources of the PSFCH transmitted by a V2X UE can be defined as K3 OFDM symbols and M resource blocks, respectively. In this case, regardless of the UE's location (within, outside, or partially covered by the base station), all V2X UEs can use the same K3 and M values. As another example, at least one of K3 and M can be configured by the base station or the V2X UE. More specifically, the base station can send information about the SL resource pool to the V2X UEs present in its cell via System Information (SIB) or RRC configuration. In this case, the information about the resource pool can include at least one of K3 and M. As another example, when V2X transmitting / receiving UEs performing unicast or multicast communication communicate via, for example... Figure 3 When configuring the PC-5 RRC to exchange AS layer parameters as described above, at least one of K3 and M can be configured. As another example, at least one of K3 and M can be a pre-configured value.

[0159] When the PSFCH uses two or more formats (e.g., one PSFCH format is used to send SL feedback information of 2 bits or less, and another PSFCH format is used to send SL feedback information including more than 2 bits), at least one PSFCH format may use a fixed value for at least one of K3 and M.

[0160] Figure 8A and Figure 8B This is a diagram illustrating an example of time axis resource allocation for the SL feedback channel according to an embodiment.

[0161] Resource allocation on the PSFCH timeline can signify the starting point of resources capable of transmitting PSFCH and the period during which such resources exist. Specifically, the starting point of resources capable of transmitting PSFCH can include the index of the time slot capable of transmitting PSFCH or the index of the time slot capable of transmitting PSFCH and the symbol index within the corresponding time slot.

[0162] Figure 8A This diagram illustrates a method for allocating a resource pool for the PSFCH, and shows the case where the PSFCH resource pool is allocated independently of the configuration of the resource pools for transmitting the PDCCH and PSSCH. In other words, it shows that the PSFCH resources begin at slot index 8 of system frame "1" with reference system frame number "0", and such PSFCH timeline resources repeat at a period of N. Based on this information, the V2X receiving UE can send its HARQ-ACK / NACK information to the V2X transmitting UE via the PSFCH in the slot where the PSFCH exists.

[0163] When there is no base station (i.e., when the V2X receiving UE is outside the coverage of the base station), the starting point of the resource pool where the PSFCH can be transmitted can be configured by referring to the direct frame number (DFN) 0.

[0164] The above PSFCH time-axis resource allocation method can be regarded as being described in terms of the system. In other words, in the V2X system, the starting time slot and period of the PSFCH resource pool can be configured, which may not mean that a V2X receiving UE needs to always use the corresponding resources. As an example, in terms of the system, the PSFCH resource pool can start from time slot "8" of system frame "1", and the period can have N time slots, as Figure 8A shown. Only when a specific V2X receiving UE needs to transmit the PSFCH of the PSFCH resource pool in terms of the system can the V2X receiving UE use the PSFCH resources. For example, the time point when the V2X receiving UE needs to transmit the PSFCH can be K time slots after the time point when the V2X receiving UE receives the PSCCH and PSSCH from the V2X transmitting UE. The timing relationship "K" between the PSCCH / PSSCH and the PSFCH can be configured for each PSFCH resource pool. "K" can be different for each PSFCH resource pool, or the same value can be used throughout the PSFCH resource pool.

[0165] In terms of the system, the PSFCH resource pool period N can be set to 1 or an integer greater than 1. According to the relationship between N and K described (i.e., N = K, N < K or N > K), the resources of the PSFCH that need to be transmitted by a specific V2X receiving UE may not exist in the corresponding time slots. For example, when Figure 8AAssuming N is 4, for the system as a whole, PSFCH timeline resources can exist in every four time slots. In other words, referring to time slot 8 of system frame 1, PSFCH timeline resources can exist in time slots 2 and 6 of system frame 2, and time slots 0, 4, and 8 of system frame 3. In this case, assuming K=4 (i.e., the V2X receiving UE sends PSFCH in four time slots after receiving PSCCH / PSSCH from the V2X transmitting UE) and the V2X receiving UE receives PSCCH / PSSCH in time slot 9 of system frame 1, the V2X receiving UE needs to send HARQ-ACK / NACK information via PSFCH in time slot 3 of system frame 2. However, since there are no PSFCH resources in the corresponding time slot, the V2X receiving UE may not be able to send PSFCH. In this case, the V2X receiving UE can send PSFCH in the earliest existing PSFCH time slot in the time slot where the V2X receiving UE needs to send PSFCH. In other words, in the example above, the V2X receiving UE can send HARQ-ACK / NACK information through PSFCH in slot 6 of system frame 2.

[0166] Figure 8B This is a diagram illustrating another example of time axis resource allocation for the SL feedback channel according to an embodiment.

[0167] Figure 8A This illustrates the scenario where the PSFCH resource pool is allocated independently of the resource pool configuration used for sending PSCCH and PSSCH. Figure 8A different, Figure 8B This illustrates a method for configuring the PSFCH resource pool within the resource pool for transmitting PSCCH and PSSCH. In other words, the resources for PSCCH and PSSCH can begin at slot index 3 of system frame "1" with reference system frame number "0". This starting point can be referred to as offset 1. Since the PSFCH exists within the resource pool for PSCCH and PSSCH, the starting point of the PSFCH can be determined by referencing offset 2 from the start time of the PSCCH / PSSCH. In other words, the start of the PSFCH resource can be identified at slot index "8", which is five slots following slot index 3 of system frame "1". Figure 8B The PSFCH timeline resource is shown to repeat in period N. Based on this information, the V2X receiving UE can send HARQ-ACK / NACK information to the V2X sender via PSFCH in a time slot where PSFCH is present.

[0168] The PSFCH time axis resource allocation method described above can be considered as a system-level description. Therefore, as Figure 8AAs described above, from a system perspective, the PSFCH resource may not exist in the time slot where a specific V2X receiving UE needs to send the PSFCH. In this case, the V2X receiving UE can send the PSFCH in the earliest existing PSFCH time slot, referencing the time slot where the V2X receiving UE needs to send the PSFCH, such as... Figure 8A As described in [the text].

[0169] Figure 9A This is a diagram illustrating an example of the resource structure of the SL feedback channel according to an embodiment. Figure 9B This is a diagram illustrating an example of the resource structure of the SL feedback channel according to an embodiment.

[0170] refer to Figure 9A and Figure 9B , Figure 9A and Figure 9B The PSFCH resource structure can mean that in Figure 4 and Figure 5 The resource structure of the PSFCH sent by the V2X receiving UE to the V2X sending UE in the unicast communication procedure shown. Furthermore, Figure 9A and Figure 9B The PSFCH resource structure can mean that in situations such as Figure 4 The resource structure of PSFCH used in the multicast communication shown, where each V2X receiving UE sends HARQ ACK and NACK information to the V2X (Option 2), is illustrated. Furthermore, Figure 9A and Figure 9B The PSFCH resource structure can mean that in situations such as Figure 4 The resource structure of PSFCH used in the multicast communication shown is in the case where multiple V2X receiving UEs in the group only send NACK information to V2X UEs (Option 1).

[0171] In the aforementioned unicast and multicast communications, each V2X receiving UE can use... Figure 9A and Figure 9B The PSFCH resource structure is used by the V2X UE to send SL Feedback Control Information (SFCI). In this case, the PSFCH used by a V2X receiving UE for SFCI transmission may include T symbols on the time axis and L frequency blocks (resource blocks (RBs) on the frequency axis, such as... Figure 9A Or as shown in 9B. T and L can both be 1, and when T=L=1, each V2X receiving UE can send a PSFCH to the V2X transmitting UE that includes one OFDM symbol and one RB on the time axis. In this case, one RB can include 12 subcarriers or 12 reference elements (REs). Furthermore, when in Figure 9A and Figure 9BWhen L>1, a PSFCH resource comprising L RBs can be considered a PSFCH subchannel. In this case, the number of PSFCH subchannels that a V2X receiving UE can use for SFCI transmission can be [x]. In this case, the value of [x] can be 1 or greater than 1, and can be configured via RRC from the base station or via PC-5 RRC (or the value [x] can be preset). Information about the above value [x] can be included in the SL resource pool configuration information.

[0172] exist Figure 9A and Figure 9B In this disclosure, it is assumed that the DMRS overhead is 1 / 3 (i.e., four of the 12 resource elements (REs) are used as DMRS), but this disclosure is not limited to this. For example, if the DMRS overhead is 1 / 4, i.e., if three of the 12 REs are used as DMRS, then the DMRS can be mapped to RE indices 1, 5, and 9 (or 2, 6, and 10), and the SFCI can be mapped to the remaining RE indices. Although Figure 9A and Figure 9B The PSFCH structure for a single RB comprising 12 REs is shown, but the same PSFCH structure applies to PSFCHs comprising two or more RBs. In other words, assuming the two RBs are the size of the PSFCH frequency resources transmitted by a V2X receiving UE, DMRS can be mapped to RE indices 1, 4, 7, 10, 13, 16, 19, and 22, and SFCI can be mapped to the remaining RE indices. Based on this principle, PSFCH structures comprising more than two (L>2) RBs can be extended and determined.

[0173] Simultaneously, when a PSFCH sent by a V2X receiving UE includes two or more OFDM symbols on the time axis, a PSFCH including one OFDM symbol can be repeated. In other words, as... Figure 9A As shown, a PSFCH comprising two or more OFDM symbols has a repeating structure of a PSFCH comprising one OFDM symbol, and DMRS can exist in REs at the same position in each OFDM symbol. In a PSFCH comprising two or more OFDM symbols, the position of the REs containing DMRS can vary for each OFDM symbol. This can be intended to reduce DMRS overhead. For example, DMRS can exist only in odd-numbered OFDM symbols and may not exist in even-numbered OFDM symbols. Alternatively, DMRS can exist only in even-numbered OFDM symbols and may not exist in odd-numbered OFDM symbols.

[0174] As another example, although Figure 9AThis illustrates that even as the number of OFDM symbols increases, the DMRS still exists in the same RE on the frequency axis, but the location of the DMRS can vary for each OFDM symbol. For example, the DMRS positioning in the first OFDM symbol and the second OFDM symbol can be different. In other words, compared to... Figure 9A Compared to a PSFCH structure comprising two OFDM symbols, the DMRS can be located at RE indices 0 and 7 in the first OFDM symbol, and at RE indices 3 and 11 in the second OFDM symbol. Alternatively, the DMRS locations in even-numbered OFDM symbols and odd-numbered OFDM symbols can differ, but the DMRS locations in even-numbered OFDM symbols can be the same (i.e., the DMRS locations in the second and fourth OFDM symbols can be the same), and the DMRS locations in odd-numbered OFDM symbols can be the same (i.e., the DMRS locations in the first and third OFDM symbols can be the same). This can be summarized as meaning that the DMRS RE locations can be the same in at least two or more OFDM symbols.

[0175] exist Figure 9A In this approach, SFCI information can be mapped to all REs of the PSFCH without DMRS. In this case, there may be a drawback that channel estimation cannot be performed due to the absence of DMRS. However, when SFCI information is transmitted based on sequences, the receiver can receive the SFCI without channel estimation, and therefore, the reception performance of the PSFCH can be improved by increasing the sequence length used for SFCI transmission and reducing DMRS overhead. (Reference) Figure 10 A detailed description of a specific example of a sequence-based SFCI transmission method.

[0176] Figure 9B This is a diagram illustrating another example of the resource structure of the SL feedback channel according to an embodiment.

[0177] refer to Figure 9BThe PSFCH resource structure is the structure of the receiver of the transmitting UE used to receive the PSFCH when configuring Automatic Gain Control (AGC). More specifically, the receiver of the transmitting UE needs to set an AGC range to receive the PSFCH. In this case, the receiving UE used to transmit the PSFCH can be located adjacent to the transmitting UE used to receive the PSFCH, or it can be located far away from the transmitting UE used to receive the PSFCH. For example, it can be assumed that UE-A is located adjacent to the transmitting UE used to receive the PSFCH, and UE-B is located far away from the transmitting UE used to receive the PSFCH. In this case, the PSFCH transmitted by UE-A can be received by the transmitting UE with high receive power, and the PSFCH transmitted by UE-B can be received by the transmitting UE with low receive power. When the transmitting UE used to receive the PSFCH configures AGC according to the PSFCH of UE-A, the PSFCH transmitted by UE-A can be quantized with a wide interval. In this case, the PSFCH transmitted by UE-B has a low receive signal level, and therefore can therefore be appropriately expressed as the quantized value described above. Therefore, the PSFCH transmitted by UE-B may not be received correctly. Similarly, when the transmitting UE configuring AGC based on UE-B's PSFCH, the PSFCH transmitted by UE-B has a low receive signal, and therefore the receive signal of the PSFCH transmitted by UE-A falls outside the AGC range, thus the receive signal of the PSFCH transmitted by UE-A may be distorted. Therefore, the PSFCH transmitted by UE-A may not be received correctly. To solve this problem, the receiver of the transmitting UE needs to configure the AGC range for a sufficient amount of time to ensure many samples are received when the PSFCH is received.

[0178] To execute this AGC range configuration, such as Figure 9B As shown, instead of mapping DMRS, SFCI information can be mapped to the first symbol. More specifically, as... Figure 9A As shown, when DMRS is mapped to the first symbol and the first symbol is used for AGC range configuration, the channel estimation performance using DMRS may degrade. Therefore, when the first symbol is used for AGC range configuration, DMRS may not be mapped to the first symbol, as... Figure 9B As shown. As another example, instead of mapping SFCI information to the first symbol, a sequence can be sent to assist the UE in receiving the PSFCH during AGC configuration. In other words, a preamble for AGC training can be sent in the first symbol of the PSFCH. Except that no DMRS is mapped to the first symbol, the localization of the DMRS mapped to the remaining symbols can follow... Figure 9A One of the methods illustrated in the example. For instance, the location of the REs for the DMRS can be the same or different for each OFDM symbol.

[0179] As another example, it can be found Figure 9B The AGC preamble is transmitted in the first symbol, and only the SFCI can be transmitted in the second symbol without the DMRS. In this case, the SFCI can be transmitted in sequence. As an example, assuming a 1-bit HARQ ACK transmission, sequence-A can be used for ACK information transmission, and sequence-B can be used for NACK information transmission. This sequence-based transmission does not require channel estimation for demodulation and decoding, and therefore the aforementioned feedback channel resource structure is possible. (Reference) Figure 10 Describe in detail the sequence-based SFCI transmission method.

[0180] Figure 10 This is a diagram illustrating an example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0181] like Figure 10 As shown, a V2X transmitting UE can transmit PSCCH and PSSCH in time slot nK. A V2X receiving UE can decode PSCCH to obtain SL control information and obtain information about the time / frequency / code resources of PSSCH from it. Figure 10 The illustration shows the transmission of PSCCH and PSSCH in the same time slot, but this disclosure is not limited thereto. In other words, PSCCH can be transmitted in time slot nK, but PSSCH can be transmitted in a subsequent time slot. In this case, the timing relationship between PSCCH and PSSCH can be fixed (e.g., PSSCH is transmitted 4 ms after PSCCH reception) or can be configured by the base station. As another example, the V2X transmitting UE can indicate the timing relationship between PSCCH and PSSCH in the SL control information transmitted by the V2X transmitting UE. The V2X receiving UE, having already obtained the SL control information, can decode PSSCH using information about the frequency / code resources of PSSCH and the timing relationship between PSCCH and PSSCH.

[0182] A V2X receiving UE can receive the PSCCH and PSSCH sent by a V2X sending UE, perform decoding, and then send feedback to the V2X sending UE via PSFCH regarding whether the PSSCH decoding was successfully performed (i.e., HARQ-ACK / NACK). Therefore, the V2X receiving UE needs to know the frequency and timing resources of the PSFCH used to send HARQ-ACK and HARQ-NACK information. Thus, in order for the V2X sending UE to receive the PSFCH from the V2X receiving UE, the V2X sending UE needs to know the frequency and timing resources of the PSFCH sent by the receiving UE.

[0183] Depending on the entity allocating the resources or how the signaling for resource allocation is designed, there can be various methods for allocating frequency resources for the PSFCH.

[0184] As an example of an entity used for resource allocation, the V2X receiving UE itself can select the resources of the PSFCH to be transmitted. More specifically, the base station can configure a PSFCH resource pool to the V2X receiving UE in the cell through system information and RRC configuration. When no base station is present, the PSFCH resource pool can be pre-configured. The V2X receiving UE can directly select the PSFCH resources to be transmitted from either the base station-configured or pre-configured PSFCH resource pool. For example, the V2X receiving UE can select PSFCH resources through sensing operations. However, in this method, PSFCH can only be transmitted if sensing is successfully performed, which may cause delays in HARQ operations and is therefore potentially undesirable. In this case, sensing operations could mean decoding SL control information transmitted on the SL control channel or decoding SL control information and measuring the reference signal received power (RSRP) via DMRS transmitted on the SL data channel.

[0185] As another example of an entity used for resource allocation, the base station can directly allocate PSFCH frequency resources to a V2X receiving UE that wants to send PSFCH to it via DCI. Alternatively, the base station can configure the set of PSFCH frequency resources available to each V2X receiving UE via RRC and indicate the frequency resources in the set to be used via DCI. This method can only be applied when the V2X receiving UE is in an RRC connected state with the base station. Therefore, a V2X receiving UE in an RRC disconnected state needs to perform random access for configuring an RRC connection with the base station, which may lead to increased signaling overhead. Furthermore, this method cannot be used when the V2X receiving UE is outside coverage.

[0186] As another example of an entity used for resource allocation, the base station can directly allocate PSFCH frequency resources to V2X transmitting UEs that want to receive PSFCH (i.e., V2X transmitting UEs that transmit PSCCH and PSSCH) via DCI. Alternatively, the base station can configure the set of PSFCH frequency resources that each V2X transmitting UE can use via RRC and indicate the frequency resources in the set of frequency resources to be used via DCI. This method can be implemented in... Figure 2The method described in the text uses the Mode 1 resource allocation method. However, in the Mode 1 resource allocation method, the base station can transmit frequency resource allocation information for the PSCCH and PSSCH sent by the UE to the V2X via DCI. Therefore, when the PSFCH frequency resource allocation information is included in the DCI, the amount of resource allocation information transmitted via DCI may increase. Furthermore, this method may only be applicable to the Mode 1 resource allocation method as described above, and not to the Mode 2 resource allocation method.

[0187] To solve this problem, Figure 10 In this process, it is necessary to introduce the correlation between the frequency resources of PSSCH sent by V2X transmitting UE (i.e., received by V2X receiving UE) and the frequency resources of PSFCH sent by V2X receiving UE (i.e. received by V2X transmitting UE), and at least one of the following methods can be used.

[0188] Method 1) The starting Physical Resource Block (PRB) index of the PSSCH sent by the UE in time slot nK via V2X can be correlated with the starting PRB index of the PSFCH sent by the UE in time slot n via V2X. See below for reference. Figure 11 , Figure 12 Figure 13 Figure 14 and Figure 15 These methods are described in detail.

[0189] For example, if the starting PRB index of the PSSCH in time slot nK is M, the starting PRB index of the PSFCH in time slot n can also be the same M. As another example, if the starting PRB index of the PSSCH in time slot nK is M, the PSFCH in time slot n can start at (M + offset) (or (M - offset)). In this case, the unit of offset can be PRB, and it can be a fixed value used the same by all V2X UEs or a value configured to vary for each resource pool. For example, in resource pool 1, 10 can be used as the offset value, and in resource pool 2, 20 can be used as the offset value. In this case, K can be a value equal to or greater than 0.

[0190] Similar to this example, the last PRB index of the PSSCH sent by the V2X-transmitting UE in time slot nK can be correlated with the starting PRB index of the PSFCH sent by the V2X-receiving UE in time slot n.

[0191] Method 2) The starting PRB index of the PSCCH transmitted by the V2X-transmitting UE in time slot nK can be correlated with the starting PRB index of the PSFCH transmitted by the V2X-receiving UE in time slot n. (See reference...) Figure 16 , Figure 17 , Figure 18 and Figure 19 Method 2 is described in detail.

[0192] Method 2 is similar to Method 1, but unlike Method 1, it can mean that the starting PRB index of the PSFCH is not related to the PSSCH, but is related to the PSCCH. For example, if the starting PRB index of the PSSCH in slot nK is M, the starting PRB index of the PSFCH in slot n can be the same M. As another example, if the starting PRB index of the PSSCH in slot nK is M, the PSFCH in slot n can start at (M + offset) (or (M - offset)). In this case, the unit of offset can be PRB, and it can be a fixed value used the same by all V2X UEs or a value configured to vary for each resource pool. For example, in resource pool 1, 10 can be used as the offset value, and in resource pool 2, 20 can be used as the offset value. In this case, K can be a value equal to or greater than 0.

[0193] Method 3) Unlike Methods 1 and 2, the initial PRB of PSFCH is not related to PSSCH or PSCCH.

[0194] For example, a V2X transmitting UE can send the starting PRB index of the PSFCH to a V2X receiving UE via SL control information. This information can be a value configured or indicated to the V2X transmitting UE by the base station. In other words, the starting PRB index of the PSFCH can be transmitted to the V2X transmitting UE via system information or RRC configuration, or indicated via DCI. The V2X transmitting UE, having received this information, can send the corresponding information to the V2X receiving UE via SL control information. In this case, a fixed value can always be used for the number of PRBs constituting the PSFCH. Alternatively, the number of PRBs in the PSFCH, along with the starting PRB index, can also be transmitted from the base station via DCI and can be included in the SL control information and sent to the V2X receiving UE.

[0195] - As another example, the starting PRB index (or the last PRB index) of the PSFCH can be inferred by the V2X receiving UE through the destination ID or source ID sent via the PSCCH or PSSCH. The V2X sending UE can transmit information about the number of PRBs constituting the PSFCH to the V2X receiving UE via the SCI. Alternatively, a fixed value can always be used for the number of PRBs constituting the PSFCH.

[0196] - As another example, the base station can transmit a set of starting PRB indices of the PSFCH to the V2X transmitting UE via system information or RRC configuration, and the V2X transmitting UE that has received the set can select one of the values ​​included in the set and send it to the V2X receiving UE via SL control information.

[0197] As described in the examples above, PSFCH frequency resources may require information about the number of resource blocks constituting the PSFCH and information about the starting PRB of the frequency. Information about the number of resource blocks constituting the PSFCH can be obtained using at least one of the following methods, as well as the methods described above.

[0198] PSFCH format 1 can transmit one or two bits of HARQ-ACK or HARQ-NACK information. When transmitting one bit of HARQ-ACK / NACK information, sequence 1 can mean HARQ-ACK information, and sequence 2 can mean HARQ-NACK information. When transmitting two bits of HARQ-ACK / NACK information, four sequences can be used: sequence 1 can mean (ACK, ACK), sequence 2 can mean (ACK, NACK), sequence 3 can mean (NACK, NACK), and sequence 4 can mean (NACK, ACK). Therefore, PSFCH format 1 can be referred to as sequence-based transmission. In contrast, there may be cases where two or more bits of HARQ-ACK / NACK information are transmitted. In this case, channel coding / decoding can be used, and such a format can be referred to as PSFCH format 2. For ease of description, two PSFCH formats have been illustrated, but more PSFCH formats may exist depending on the type of SL feedback information transmitted via PSFCH and the bit size of the SL feedback information transmitted via PSFCH.

[0199] Regardless of the exemplified PSFCH format, the same number of PRBs can be used. In this case, the PRB values ​​are fixed values ​​previously known to all V2X UEs. As another example, different fixed values ​​can be used depending on the exemplified PSFCH format. In other words, PSFCH format 1 can use one PRB, and PSFCH format 2 can use four PRBs.

[0200] As another example, the number of PRBs used for the PSFCH can use different values ​​through base station configuration or pre-configuration. For instance, the base station can include the presence or absence of the PSFCH in the resource pool configuration information, and when the PSFCH exists in the corresponding resource pool, it can include information about the number of PRBs constituting the PSFCH.

[0201] HARQ-ACK / NACK messages sent by a V2X receiving UE in multicast or unicast communication can be sent via one PSFCH resource or two PSFCH resources. When sending messages via one PSFCH, the above method can be applied. However, when sending messages via two PSFCH resources (i.e., one PSFCH resource for HARQ-ACK transmission and another for HARQ-NACK transmission), a method for informing the starting points of the two PSFCH resources may be required.

[0202] When two PSFCH resources exist consecutively, the starting PRB index of the first PSFCH resource can be derived from the starting PRB index of the PSSCH as described above. In other words, in the example, the starting PRB index of the first PSFCH resource can be M or (M + offset) (or (M - offset)). Furthermore, the starting PRB index of the second PSFCH resource can be determined depending on the number of PRBs constituting the first PSFCH resource. For example, if we assume the number of PRBs constituting the first PSFCH resource is [X1], then the starting PRB index of the second PSFCH resource can be (M + [X1]) or (M + offset + [X1]) (or (M - offset - [X1])). In this case, for [X1], a fixed value can be used, or [X1] can be configured by the UE via the base station or V2X.

[0203] When two PSFCH resources are not contiguous, the starting PRB index of the first PSFCH resource can be derived from the starting PRB index of the PSSCH, and the starting PRB index of the second PSFCH resource can be configured using separate offsets as described above. For example, in the example, the starting PRB index of the first PSFCH resource can be M or (M + offset 1) (or (M - offset 1)). The starting PRB index of the second PSFCH resource can be (M + offset 2) or (M + offset 1 + offset 2) (or (M - offset 1 - offset 2)). In this case, offset 1 can represent the difference between the starting PRB index of the PSSCH and the starting PRB index of the PSFCH, and offset 2 can represent the difference between the starting PRB index of the first PSFCH resource and the starting PRB index of the second PSFCH resource.

[0204] As another example, the starting PRB index of the second PSFCH resource can be (M + [X1] + offset 2) or (M + offset 1 + [X1] + offset 2) (or (M - offset 1 - [X1] - offset 2)). In this case, [X1] means the number of PRBs constituting the first PSFCH resource, and for [X1], a fixed value can be used, or [X1] can be configured by the base station or V2X sent to the UE. Additionally, in this example, offset 1 can mean the difference between the starting PRB index of the PSSCH and the starting PRB index of the PSFCH. Furthermore, offset 2 can mean the difference between the starting PRB index of the first PSFCH resource and the starting PRB index of the second PSFCH resource.

[0205] Figure 11 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0206] Figure 11 This illustrates the case where the starting PRB index of PSSCH transmitted by different V2X transmitting UEs is the same. In other words, this means the starting PRB index of the PSSCH transmitted by V2X transmitting UE 1 to V2X receiving UE 1 in time slot nK is the same as the starting PRB index of the PSSCH transmitted by V2X transmitting UE 2 to V2X receiving UE 2 in time slot n-K+1. Because PSSCHs transmitted in different time slots use the same starting PRB index, if a reference is applied... Figure 10 The described method assumes that the starting PRB index of the PSFCH is the same, and therefore conflicts may occur between PSFCHs. This problem can arise not only when different V2X transmitting UEs send PSFCHs to different V2X receiving UEs, but also when different V2X transmitting UEs send PSFCHs to the same V2X receiving UE, such as... Figure 11 As shown in the example (i.e., when the PSCCH / PSSCH sent by V2X sending UE 1 and the PSCCH / PSSCH sent by V2X sending UE 2 are sent to V2X sending UE 1), this PSFCH conflict problem can be resolved using one of the following methods.

[0207] Method 1) The starting PRB index of PSSCH and the V2X UE ID indicate the starting PRB index of PSFCH.

[0208] A V2X UE ID can mean either the destination ID or the source ID, or both. The [X1] bits of the destination ID, including the [X] bits, can be sent via PSCCH, and the remaining [X2] bits can be included in the MAC PDU sent via PSCCH ([X] = [X1] + [X2]). The [Y1] bits of the source ID, including the [Y] bits, can be sent via PSCCH, and the remaining [Y2] bits can be included in the MAC PDU sent via PSCCH ([Y] = [Y1] + [Y2]). In the example, [X2] and [Y2] can be 0 bits. This could mean sending only the destination ID and source ID via PSCCH. Furthermore, in the example, [X1] and [Y1] can be 0 bits. This could mean sending only the destination ID and source ID via PSCCH.

[0209] A V2X receiving UE can decode PSCCHs sent by different V2X transmitting UEs in different time slots and obtain partial (when the destination ID and source ID bits are split and sent in the MAC PDU of the PSCCH and PSSCH) or all (when the destination ID or source ID bits are sent only through the PSCCH) V2X UE ID information. Furthermore, a V2X receiving UE that has successfully performed PSCCH decoding can obtain information about the frequency resources of the PSSCH and obtain partial (when the destination ID or source ID bits are split and sent in the MAC PDU of the PSCCH and PSSCH) or all (when the destination ID or source ID bits are sent only through the PSSCH) V2X UE ID information.

[0210] The destination ID is the ID used to identify the receiving UE of the PSSCH sent by the V2X sending UE. The source ID is the ID used to identify the sending UE of the PSSCH sent by the V2X sending UE. This method can be further subdivided into the following methods depending on whether the source ID or the destination ID is used to identify the starting PRB index of the PSSCH.

[0211] Method 1-1) Using the source ID

[0212] Since different V2X transmitting UEs can send different PSSCHs to the same V2X receiving UE, the PSFCH conflict problem still exists if an offset is given to the starting PRB index of the PSSCH sent in different time slots via the destination ID, because the same destination ID is used. Therefore, an offset can be given to the starting PRB index of the PSFCH via the source ID.

[0213] More specifically, such as Figure 11As shown, PSCCH-1 or PSSCH-1 transmitted by V2X UE 1 in time slot nK has source ID 1. PSCCH-2 or PSSCH-2 transmitted by UE 2 in time slot n-K+1 has source ID 2. Even when PSCCH-1 and PSSCH-2 have the same starting PRB index, the starting PRB index of PSFCH transmitted in time slot n can vary because different source IDs are used. In other words, different source IDs can give different offsets to the starting PRB index of PSFCH.

[0214] In this scenario, the relationship between the source ID and the offset of the starting PRB index of the PSFCH can be pre-configured or configured by the higher layers of the base station or UE. As another example, the source ID can be converted to a decimal number and interpreted as an offset. More specifically, it can be assumed that the source ID consists of 4 bits and that source ID 1 = 0011 and source ID 2 = 1011. In this case, when source ID 1 is converted to decimal, it can be expressed as source ID 1 = 3 and source ID 2 = 11. Therefore, the PSFCH corresponding to PSSCH-1 transmitted by V2X-transmitting UE 1 can have an offset of 3, and the PSFCH corresponding to PSSCH-2 transmitted by V2X-transmitting UE 2 can have an offset of 11. For ease of description, a source ID consisting of 4 bits is illustrated, but the number of bits in the source ID can be larger (e.g., 24 bits). In this case, since the offset value becomes very large, it may deviate from the index range of the frequency resources in the corresponding resource pool. In this case, modulo operation can be performed. Furthermore, in this example, all bits that make up the source ID are converted to decimal numbers to express the offset value, but some bits of the source ID (e.g., the most significant bit (MSB) [K1] or the least significant bit (LSB) [K1]) can be converted to decimal numbers and interpreted as offsets.

[0215] Method 1-2) Using Destination ID

[0216] A V2X transmitting UE can send PSFCH to different V2X receiving UEs in different time slots. In this case, since the source ID is the same but the destination ID may be different, PSFCH collisions may still occur when using the source ID to determine the starting PRB index of the PSFCH. Therefore, an offset can be given to the starting PRB index of the PSFCH based on the destination ID. The method exemplified when using the source ID can be used.

[0217] Method 2) The starting PRB index of PSSCH and the index of the time slot for sending PSSCH indicate the starting PRB index of PSFCH.

[0218] like Figure 13AAs shown, the frequency resources of the PSFCH can be grouped into frequency resources that can be used in each time slot. In other words, they can be... Figure 12 The scenario where HARQ-ACK / NACK information is sent in time slot 8 corresponds to the scenario where the V2X receiving UE receives PSSCH in time slots 2, 3, 4, and 5. Therefore, the number of groups into which frequency resources need to be divided in time slots where PSSCH can be sent can be determined based on K and N, or one of these two values. Figure 12 In the example, assume K=3 and N=4, and... Figure 13A In this context, the PSFCH frequency resources are divided into four groups. For example... Figure 13A As shown, the PSFCH frequency resources available to each group (i.e., the number of PRBs constituting the PSFCH) can be the same or different. The starting PRB index of the PSFCH can be determined through this grouping and its correlation with the starting PRB index of the PSSCH illustrated in Figure 8. Therefore, the PSFCH collision problem can be resolved even when different PSSCHs are sent using the same starting PRB index in different time slots, because the starting PRB index of the PSFCH can be configured to vary.

[0219] Figure 12 This is a diagram illustrating another example of time axis resource allocation for the SL feedback channel according to an embodiment.

[0220] exist Figure 12 In the example, the PSFCH timeline resource starts from slot 0 and has a period of 4 slots (N=4). Therefore, the PSFCH timeline resource can exist in slots 0, 4, 8, 2, and 6. Furthermore, in Figure 12 In this context, assume the time relationship K between the PSSCH sent by the V2X transmitting UE (i.e., the PSSCH received by the V2X receiving UE) and the PSFCH to be sent by the V2X receiving UE is three time slots. In other words, the V2X receiving UE can decode the PSSCH sent by the V2X transmitting UE and prepare HARQ-ACK and HARQ-NACK information for sending the PSFCH within a timeframe shorter than three time slots. Therefore, the HARQ-ACK / NACK information corresponding to the PSSCH received by the V2X receiving UE in time slots 0 and 1 can be sent in time slot 4, such as... Figure 12 As shown in the diagram, HARQ-ACK / NACK information corresponding to the PSSCH received by the V2X receiving UE in time slots 2, 3, 4, and 5 can be sent in time slot 8. Furthermore, HARQ-ACK / NACK information corresponding to the PSSCH received by the V2X receiving UE in time slots 6, 7, 8, and 9 can be sent in time slot 2.

[0221] Figure 13A This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0222] Figure 13A This demonstrates the grouping of frequency resources in the PSFCH to address... Figure 11 The PSFCH conflict problem described in [the document]. For example... Figure 13A As shown, the frequency resources of the PSFCH can be grouped into frequency resources available in each time slot. In other words, it is possible to... Figure 12 The scenario where HARQ-ACK / NACK information is sent in time slot 8 corresponds to the scenario where the V2X receiving UE receives PSSCH in time slots 2, 3, 4, and 5. Therefore, the number of frequency resources that need to be divided into groups within the time slots where PSSCH can be sent can be determined by one or both of the values ​​K and N. Figure 12 In the example, assume K=3 and N=4, and... Figure 13A In this context, the PSFCH frequency resources are divided into four groups. For example... Figure 13A As shown, the PSFCH frequency resources available to each group (i.e., the number of PRBs constituting the PSFCH) can be the same or different. The starting PRB index of the PSFCH can be determined through this grouping and its correlation with the starting PRB index of the PSSCH illustrated in Figure 8. Therefore, the PSFCH collision problem can be resolved even when different PSSCHs are sent using the same starting PRB index in different time slots, because the starting PRB index of the PSFCH can be configured to vary.

[0223] Figure 13B This is a diagram illustrating a specific example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0224] Figure 13B yes Figure 13A Specific embodiments are shown, and such embodiments are illustrated. Figure 12 The example shown illustrates a case where the PSFCH resource associated with the PSCCH or PSSCH received by the receiving UE in time slots 2, 3, 4, and 5 exists in time slot index 8. The total number of PSCCH or PSSCH receive time slots associated with the PSFCH transmit resource is defined as L (in Figures 12 to 13A In the example above, the number of PRBs constituting each PSCCH or PSSCH receive slot associated with the PSFCH transmit resource can be defined as M. In this case, M can be defined as the total number of PRBs constituting a SL resource pool, and the total number of PRBs in the frequency axis within the SL resource pool is the same across all slots constituting the SL resource pool. In the example above, the number of PSCCH or PSSCH receive slots associated with the PSFCH transmit resource (i.e., L=4) is... Figure 12 , 13A The set of slots 2, 3, 4 and 5 shown in 13B can be physically contiguous or logically contiguous (if logically contiguous, physically discontinuous). Furthermore, the M PRBs constituting each receive slot of the PSCCH or PSSCH can also be physically contiguous or logically contiguous.

[0225] exist Figure 13B In this context, the PSCCH or PSSCH receive slot indices 2, 3, 4, and 5 associated with the PSFCH transmit resource can be interpreted as slot indices 0', 1', 2', and 3', respectively. More generally, assuming L physically contiguous or discontinuous PSCCH or PSSCH receive slots associated with the PSFCH transmit resource, the corresponding PSCCH or PSSCH receive slots can be interpreted in chronological order as slot indices 0', 1', ..., and (L-1)'. Since... Figure 13B The case of L=4 is shown, so the corresponding PSCCH or PSSCH receive slots can be interpreted in chronological order as slot indices 0', 1', 2', and 3'.

[0226] like Figure 10 and Figure 11 As shown, when the transmit frequency resources of PSFCH are associated with the receive frequency resources of PSCCH or PSSCH, the location of the receive frequency resources of PSCCH or PSSCH received by each receiving UE can be mapped to the location of the frequency resources used for transmitting PSFCH. Therefore, it may be necessary to require as many PSFCH transmit resources as there are available PSCCH or PSSCH resources. For example, assuming that the minimum transmit resource unit a transmitting UE can transmit is 1 PRB, in... Figure 13B Up to M PSCCHs or PSSCHs can be received in slot index 0'. Therefore, the total number of frequency resources for PSCCHs or PSSCHs associated with the frequency resources for PSFCHs can be (4 × M) PRBs. Typically, the total number of frequency resources for PSCCHs or PSSCHs associated with PSFCH transmission can be (L × M) PRBs. In this case, L can mean the total number of PSCCHs or PSSCHs associated with the PSFCH transmission resources, as described above.

[0227] The (L×M) PRB indices indicating the starting location of the frequency resources that can receive the aforementioned PSCCH or PSSCH can be mapped to the starting point of the frequency resources used for PSFCH transmission, such as... Figure 13BAs shown. In other words, the PRB indices 0, 1, ..., and (M-1) of time slot index 0', the PRB indices 0, 1, ..., and (M-1) of time slot index 1', the PRB indices 0, 1, ..., and (M-1) of time slot index 2', and the PRB indices 0, 1, ..., and (M-1) of time slot index 3' can be mapped in sequence. Based on the mapping rules, receiving UEs that have received PSCCH or PSSCH using PRB index 0 of time slot index 2 as the starting point and receiving UEs that have received PSCCH or PSSCH using PRB index 0 of time slot index 3 as the starting point can regard the PSFCH frequency resources mapped to the PRB indices and corresponding time slot indices as the starting point for frequency resources used for PSFCH transmission.

[0228] Typically, the index of the PSCCH or PSSCH receive slot associated with the frequency resources used for PSFCH transmission (i.e., Figure 13B When time slots 2 (or time slot 0'), 3 (or time slot 1'), 4 (or time slot 2'), and 5 (or time slot 3') can be defined as "l", and the index of the PRB in each time slot is defined as "m", the starting index of the PSFCH frequency resource in the time slot transmitting the PSFCH can be determined by "(l + m + offset)". In this case, the offset value is a parameter used to reduce inter-cell interference, and... Figure 13B The offset is assumed to be 0, but it can have a different value for each cell. The offset value can be configured by the base station for the UE through system information or RRC configuration, or it can be derived from the cell ID (or a virtual cell ID configured by the base station) detected by the UE from the base station's synchronization signal. For example, a UE that has obtained "0" from 0, 1, or 2 obtained through cell ID mod 3 operation can apply offset = 0, a UE that has obtained "1" can apply offset = z, and a UE that has obtained "2" can apply offset = 2z. In this case, z can be assumed to be a fixed value and known to both the base station and the UE.

[0229] In addition to the starting point of the frequency resources used for PSFCH transmission (i.e., the starting PRB index), the receiving UE also needs to know the number of PRBs required for PSFCH transmission. In this case, it can be assumed that the receiving UE knows the number of PRBs required for PSFCH transmission before PSFCH transmission. For example, a fixed value may be used for the number of PRBs required for PSFCH transmission (i.e., 2 PRBs), or the number of PRBs required for PSFCH transmission may be configured through the base station's system information or RRC, or PC-5 RRC.

[0230] In the example above, when the minimum resource unit (RPB) that a UE can use for PSCCH or PSSCH transmission is assumed to be 1 PRB, it may require (L×M) start indices of PSFCH frequency resources. In this case, if it is assumed that the number of PRBs required for PSFCH transmission is 1, then (L×M) PSFCH frequency resources may be required. However, when the number of PRBs required for PSFCH transmission is assumed to be greater than 1 ("R"), PSFCH frequency resources may require (L×M×R) PRBs. This may lead to a shortage of PSFCH frequency resources in the time slot for PSFCH transmission. For example, when the SL BWP is set to 20 MHz and an SL resource pool is configured in the SLBWP, there can be 100 PRBs in the SL resource pool. When it is assumed that the minimum transmission resource for PSCCH or PSSCH is 1 PRB and the number of PRBs required for PSFCH transmission is 1, in Figure 13B The system may require 400 (=4 × 100) PSFCH frequency resources. Since a resource pool includes 100 PRBs, the 300 UEs in the above example may not be able to perform PSFCH transmission. In the above example, when the number of PRBs required for PSFCH transmission increases to 2, it may require 800 (=4 × 100 × 2) PSFCH frequency resources, which may exacerbate the PSFCH frequency resource shortage problem.

[0231] Figure 13C This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0232] Figure 13C Another example of the mapping between the starting index of the frequency resource used for PSFCH transmission and the starting index of the frequency resource that can receive PSCCH or PSSCH is shown.

[0233] exist Figure 13B In this process, the frequency resource index of the first time slot receiving the PSCCH or PSSCH is sequentially mapped to the start index of the PSFCH frequency resource, and then the frequency resource index of the next time slot is sequentially mapped to the start index of the PSFCH frequency resource. In contrast, Figure 13C The index of the first frequency resource of the time slot receiving the PSCCH or PSSCH is shown to be mapped to the starting index of the PSFCH frequency resource, and then the frequency resources below are mapped sequentially. Figure 13C The mapping structure and Figure 13B The mapping structures are different, but they may undergo processes such as Figure 13B The problem of PSFCH frequency resource shortage in China.

[0234] Figure 13B and Figure 13CThe PSFCH frequency resource shortage problem described herein may be exacerbated by an increase in the minimum resource unit (RPU) of the PSCCH or PSSCH transmitted by the transmitting UE (e.g., one PRB) and / or an increase in the minimum resource unit of the PSFCH transmitted by the receiving UE (e.g., two or more PRBs). This problem can be addressed by increasing the minimum resource unit of the PSCCH or PSSCH and decreasing the minimum resource unit of the PSFCH transmitted by the receiving UE. For example, two or more physically or logically contiguous PRBs can be grouped into a PRB group (PRBG). In this case, the PRBG can be referred to as a subchannel, and a subchannel can be defined as the minimum resource unit for PSCCH, PSSCH, or PSFCH transmission. Furthermore, a PSCCH subchannel representing the minimum resource unit of the PSCCH, a PSSCH subchannel representing the minimum resource unit of the PSSCH, and a PSFCH subchannel representing the minimum resource unit of the PSFCH can include the same or different numbers of PRBs. For example, a PSCCH subchannel can include two PRBs, a PSSCH subchannel can include four PRBs, and a PSFCH subchannel can include one PRB. However, this is provided only as an example, and the number of PRBs constituting the PSCCH, PSSCH, and PSFCH sub-channels can be defined as α, β, and γ, respectively. In this case, fixed values ​​can be used for α, β, and γ, or the base station can configure fixed values ​​for PSCCH, PSSCH, and PSFCH respectively. Alternatively, these values ​​can be configured or pre-configured via PC-5 RRC. As mentioned above, to address the PSFCH resource shortage problem, it is necessary to satisfy α > β (when PSFCH resources are associated with PSCCH resources) or β > γ (when PSFCH resources are associated with PSSCH resources).

[0235] For example, a PSCCH subchannel or a PSSCH subchannel may include α PRBs (for ease of description, it is assumed that the number of PRBs constituting the PSCCH subchannel and the PSSCH subchannel is the same), and a PSFCH subchannel includes γ PRBs. Furthermore, as... Figure 13B and Figure 13C As shown, assuming each time slot constituting the SL resource pool comprises a total of M PRBs, then time slots that can receive PSCCH or PSSCH (e.g., Figure 13B and Figure 13CTime slots 2 (or 0'), 3 (or 1'), 4 (or 2'), and 5 (or 3') can be considered as including M / α PSCCH or PSSCH sub-channels. In this case, when M / α is not an integer, it can be rounded down or up (i.e., └M / α┘ or ┌M / α┐). Therefore, since there may be a total of (L×M / α) frequency resources capable of receiving PSCCH or PSSCH sub-channels, (L×M / α×γ) PSFCH frequency resources are required in the time slots where PSFCH resources exist. To solve the above PSFCH frequency resource shortage problem, the condition L×M / α×γ≤M needs to be satisfied. More specifically, when assuming L=4, M=100, α=4, and γ=1, the left and right sides of the above equation are both 100, and the condition is thus satisfied. Therefore, the PSFCH resource shortage problem may not occur. However, when assuming L=4, M=100, α=4, and γ=2, the left-hand side of the above equation is 200, and the right-hand side is 100, thus failing to meet the conditions. Therefore, the PSFCH resource shortage problem can still occur.

[0236] Figure 13D This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0237] Figure 13D Another example of the mapping between the starting index of the frequency resource used for PSFCH transmission and the starting index of the frequency resource that can receive PSCCH or PSSCH is shown.

[0238] and Figures 13B to 13C different, Figure 13D This illustrates a scenario where the start index of the frequency resource in which PSCCH or PSSCH can be received within a time slot is mapped to the start index of the PSFCH frequency resource, and the time slot index in which PSCCH or PSSCH can be received is mapped to the index of the PSFCH code resource. In other words, according to... Figure 13D The scheme shown can use M PRBs on the frequency axis and L codes on the code axis to express resource indices mapped to a total of (L×M) PRBs. More specifically, when the index of the PSCCH or PSSCH receive slot associated with the frequency resource used for PSFCH transmission is defined as "1" and the index of the PRB in each slot is defined as "m", the starting index of the PSFCH frequency resource in the transmit PSFCH slot can be determined by "m + offset". Furthermore, the starting index of the PSFCH frequency resource can be determined by "m + offset", regardless of the index of each PSCCH or PSSCH receive slot, and the index of each PSCCH or PSSCH receive slot can be mapped to code resources. In this case, the offset value is a parameter used to reduce inter-cell interference, and... Figure 13B The offset is assumed to be 0, but it can have a different value for each cell. The offset value can be configured for the UE by the base station via system information or RRC, or it can be derived from the cell ID (or a virtual cell ID configured by the base station) detected by the UE from the base station's synchronization signal. For example, a UE that has obtained "0" from 0, 1, or 2 obtained through cell ID mod 3 can apply offset = 0, a UE that has obtained "1" can apply offset = z, and a UE that has obtained "2" can apply offset = 2z. In this case, z can be assumed to be a fixed value and known to both the base station and the UE.

[0239] In addition to the starting point of the frequency resources used for PSFCH transmission (i.e., the starting PRB index), the receiving UE also needs to know the number of PRBs required for PSFCH transmission. It can be assumed that the receiving UE knows the number of PRBs required for PSFCH transmission before PSFCH transmission. For example, the number of PRBs required for PSFCH transmission can be a fixed value (i.e., two PRBs), or it can be configured via the base station's system information, RRC, or PC-5 RRC.

[0240] The above example can be applied to the PSCCH, PSSCH, and PSFCH subchannel concepts described above. For instance, a total of (L×M / α) PSFCH resource indices can be expressed using M / α subchannels on the frequency axis and L codes on the code axis for each time slot capable of receiving PSCCH or PSSCH. As mentioned above, when the number of PRBs constituting a PSFCH subchannel is assumed to be γ, there can be (M / α×γ) PSFCH frequency resources on the frequency axis in a time slot where PSFCH resources exist. Since the time slots constituting the SL resource pool can have a total of M PRBs on the frequency axis, a PSFCH resource shortage problem does not occur if the condition M / α×γ≤M is satisfied. In other words, a PSFCH resource shortage problem does not occur if α≥γ. Because the bit size of the SFCI sent via PSFCH is very small compared to the bit size sent via PSCCH or PSSCH (e.g., the bit size of the SFCI sent via PSFCH is 1 or 2, while the bit size sent via PSCCH or PSSCH is tens to thousands of bits), α can always be equal to or greater than γ. Therefore, since the above condition can always be satisfied, the PSFCH resource shortage problem can be avoided.

[0241] When the frequency resources of a PSCCH or PSSCH transmitted by a transmitting UE are associated with the transmission frequency resources of a PSFCH transmitted by a receiving UE, the following can be applied: Figure 13A , Figure 13B , Figure 13C and Figure 13D The example described above illustrates this. Unlike the above scenario, in multicast communication, the frequency resources for a PSCCH or PSSCH transmitted by a transmitting UE can be associated with the transmission frequency resources for a PSFCH transmitted by two or more receiving UEs. For example, consider multicast communication involving three UEs (UE-A, UE-B, and UE-C). In this case, assume UE-A is the transmitting UE sending the PSCCH or PSSCH, and UE-B and UE-C are the receiving UEs receiving the PSCCH or PSSCH. The PSCCH or PSSCH transmitted by UE-A can be received by UE-B and UE-C, and UE-B and UE-C, having already received the PSCCH or PSSCH, need to send a PSFCH to UE-A. In this case, UE-B and UE-C can send HARQ feedback information using one of two methods.

[0242] Option 1: A NACK message may be sent only if the decoding of the received PSSCH fails. In other words, when decoding of the PSSCH received from UE-A is successfully performed, UE-B and UE-C may not send an ACK message, and may only send a NACK message if the decoding of the PSSCH fails. In this case, the UE used to send the NACK message may only send it if specific conditions are met. More specifically, UE-B and UE-C do not always send a NACK message when the PSSCH fails to be decoded, but additional conditions may be determined. This condition may be the distance from UE-A or the RSRP. For example, UE-B may fail to decode the PSSCH and therefore needs to send a NACK message to UE-A, but UE-B may not send a NACK message to UE-A unless the aforementioned distance condition or RSRP condition is met. When using the distance condition, UE-A corresponding to the transmitting UE can send its location information to the receiving UEs (i.e., UE-B and UE-C). UE-B and UE-C, having received this location information, can measure the distance to UE-B or UE-C and UE-A using the location information received from UE-A and the location information measured by UE-B and UE-C. Each receiving UE can perform a comparison operation with the distance measured by the receiving UE using a distance threshold received from higher layers. When the distance measured by the receiving UE is greater than the distance threshold, each receiving UE does not send a NACK message to UE-A. Each receiving UE can send a NACK message to UE-A only when the distance measured by the receiving UE is less than the distance threshold. When using the RSRP condition, the receiving UEs in the group (i.e., UE-B and UE-C) can measure the RSRP using a reference signal (e.g., DMRS or SL CSI-RS) transmitted by the transmitting UE. Each receiving UE can perform a comparison operation with the RSRP measured by the receiving UE using a threshold of RSRP received from higher layers. When the RSRP measured by the receiving UE is greater than the RSRP threshold, no NACK message is sent to UE-A. Each receiving UE may send a NACK message to UE-A only when the RSRP measured by the receiving UE is less than the RSRP threshold.

[0243] In Option 1, all receiving UEs in the group can use the same time / frequency resources to transmit the PSFCH. Therefore, when the PSFCH frequency resource is associated with the frequency resource of the PSCCH or PSSCH, the receiving UEs used to transmit the PSFCH can use... Figure 13A , Figure 13B , Figure 13C and Figure 13D One of the methods shown in the example is for sending PSFCH.

[0244] Option 2: Unlike Option 1 above, each of the receiving UEs (UE-B and UE-C) in the same group performing multicast communication can send ACK and NACK messages to UE-A. In other words, a receiving UE that has successfully decoded the PSSCH can send ACK messages via PSFCH, and a receiving UE that has failed to decode the PSSCH can send NACK messages via PSFCH. In Option 2, the messages sent by the receiving UEs to the sending UE (UE-A) can be different from each other (i.e., UE-B sends NACK messages, and UE-C sends ACK messages). Therefore, in order for UE-A, which has received different feedback messages, to decode them accurately, the receiving UEs in the group need to use different PSFCH transmission resources. Furthermore, when UE-B and UE-C send the same message using the same PSFCH transmission resources (i.e., when both UEs send ACK or NACK), UE-A, which has received the same message, may not be able to determine which receiving UE has received the corresponding feedback message from it. Therefore, the receiving frequency resources of PSCCH or PSSCH need to be associated with two or more PSFCH frequency resources. Furthermore, the distance condition or RSRP condition described in Option 1 can be further applied to Option 2. In other words, the receiving UE in the group can only send ACK or NACK information to the sending UE if the distance condition or RSRP condition is met.

[0245] Figure 13A , Figure 13B , Figure 13C and Figure 13D The method described herein is an example of a case where the receive frequency resource of a PSCCH or PSSCH is associated with a PSFCH frequency resource, and therefore may not be applied to option 2. Therefore, it is required that the method used to... Figure 13A , Figure 13B , Figure 13C and Figure 13B The method described in [the document] is applied to the new method in option 2.

[0246] More specifically, already Figure 13B and Figure 13CThe document describes the need to satisfy the condition L×M / α×γ≤M to address the PSFCH resource shortage problem. However, this condition only applies when a PSCCH or PSSCH frequency resource is associated with a single PSFCH resource (e.g., option 1 above). As mentioned above, in option 2, since the PSCCH or PSSCH frequency resource needs to be associated with two or more PSFCH resources (i.e., multiple receiving UEs in the group need to use different PSFCH resources), the number of receiving UEs in the group needs to be considered. Therefore, when the number of receiving UEs in a group is defined as G, the condition G×L×M / α×γ≤M needs to be satisfied to address the PSFCH resource shortage problem. In application... Figure 13B and Figure 13C In the example described above, where L=4, M=100, α=4, γ=2, if we assume that the number of receiving UEs in the group is G=5, then the left side of the above equation is 5×4×100 / 4×2=1000, and the right side is 100, and therefore the condition is not satisfied.

[0247] To solve this problem, when using Figure 13B and Figure 13C In this method, receiving UEs in the group share the same PSFCH frequency resources, and the corresponding receiving UEs can transmit PSFCH using different codes. For example, assuming multicast communication including UE-1, UE-2, UE-3, UE-4, and UE-5, and assuming that UE-1 is the transmitting UE and the remaining UEs are receiving UEs in the group, in Figure 13BIn this scenario, UE-1 transmits a PSCCH or PSSCH with a starting frequency index of 0 in slot index 0', and receiving UEs (UE-2, UE-3, UE-4, and UE-5) receive this PSCCH or PSSCH. UE-2, UE-3, UE-4, and UE-5 know that the PSFCH frequency resource with slot index 0' and starting frequency index 0 is the starting frequency index capable of transmitting PSFCH. In this case, UE-2, UE-3, UE-4, and UE-5 can use the same PSFCH frequency resource but apply different codes. More specifically, UE-2, UE-3, UE-4, and UE-5 can have their own UE IDs. In this case, the UE ID can be the source ID of each receiving UE or a higher-layer ID that can identify each UE included in the same group in multicast communication. Each receiving UE knows its own UE ID and can select a code based on the ID. In this case, the code can mean the root index used to determine the sequence or cyclic shift. As another example, the code can mean an orthogonal cover code (OCC) on the time axis or an OCC on the frequency axis. Each receiving UE can select a code resource that can be used by itself through modulo operation of its own ID and a specific number "C". For example, UE-2 can obtain "0" through modulo operation of its own ID and "C", while UE-3 can obtain "1" through modulo operation of its own ID and "C". UE-2, which has obtained "0", can choose the code corresponding to "0", and UE-3, which has obtained "1", can choose the code corresponding to "1". UE-2 and UE-3 can multiply the PSFCH to be transmitted with the selected code on the time axis or frequency axis and transmit it. Therefore, UE-1 can receive PSFCH transmitted from UE-2, UE-3, UE-4, and UE-5 using different codes in the same PSFCH frequency resource.

[0248] In the above example, "C" can be a fixed value or a variable value, depending on the method used to form a group in multicast communication. More specifically, UEs in a group can know their mutual group destination IDs by exchanging information about group members before performing multicast communication. For example, when UE-1 is the transmitting UE and UE-2, UE-3, UE-4, and UE-5 are the receiving UEs in the above example, UE-1 knows the group destination IDs used by the receiving UEs before multicast transmission. In this case, "C" can vary depending on the number of group members constituting the group and can be configured while exchanging information about group members before performing multicast communication. For example, "C" can be configured via PC-5 RRC or in the resource pool information for performing multicast communication. Meanwhile, there may be cases where information about group members is unknown before performing multicast communication. In this case, since there is no information about group members, the number of group members may be unknown. In this case, a fixed value can be used as "C". As another example, within the coverage area of ​​a base station, the base station can configure the above "C" value via system information or RRC. This information can be included in the resource pool configuration information used for multicast communication.

[0249] In order to solve the problem Figure 13B and Figure 13C The PSFCH resource shortage problem caused by this, in Figure 13D In this context, different codes are used to distinguish the PSFCH resources associated with the time slots used to receive PSCCH or PSSCH. The method of selecting the PSFCH resources to be transmitted by each UE using the UE ID and the modulo operation of "C" in the example above can also be applied to... Figure 13D For example, suppose a multicast communication includes UE-1, UE-2, UE-3, UE-4, and UE-5, and it can be assumed that UE-1 is the sending UE and the remaining UEs are receiving UEs in the group. Figure 13DIn this scenario, UE-1 transmits a PSCCH or PSSCH with a starting frequency index of 0 in slot index 0', and receiving UEs (UE-2, UE-3, UE-4, and UE-5) receive this PSCCH or PSSCH. UE-2, UE-3, UE-4, and UE-5 can determine that the PSFCH frequency resource with starting frequency index 0 is a starting frequency index capable of transmitting PSFCH, and know that code 0 needs to be used to transmit PSFCH because the PSCCH or PSSCH is received in slot index 0'. In this case, UE-2, UE-3, UE-4, and UE-5 can use the same PSFCH frequency resource and the same code corresponding to slot index 0', and can apply different codes to distinguish the UEs. More specifically, UE-2, UE-3, UE-4, and UE-5 can have their own UE IDs. In this case, the UE ID can be the source ID of each receiving UE or a higher-layer ID that can identify each UE included in the same group in multicast communication. Each receiving UE knows its own UE ID and can select a code based on the ID. In this context, the code can refer to the root index used to determine a sequence or cyclic shift. As another example, the code can refer to an orthogonal overlay code (OCC) on the time axis or an OCC on the frequency axis. Each receiving UE can select the code resource available to it by performing a modulo operation between its own ID and a specific number "C". For example, UE-2 can obtain "0" by performing a modulo operation between its own ID and "C", and UE-3 can obtain "1" by performing a modulo operation between its own ID and "C". UE-2, having obtained "0", can select the code corresponding to "0", and UE-3, having obtained "1", can select the code corresponding to "1". UE-2 and UE-3 can multiply the PSFCH to be transmitted with the selected code on either the time axis or the frequency axis and transmit it. Therefore, UE-1 can receive PSFCHs transmitted from UE-2, UE-3, UE-4, and UE-5 using different codes within the same PSFCH frequency resource.

[0250] exist Figure 12 , Figure 13A , Figure 13B , Figure 13C and Figure 13D In the example, in order to correctly send and receive the PSFCH, the SL sending / receiving UE needs to know the number of bits of HARQ-ACK / NACK information included in the PSFCH, which can be determined based on a combination of one or more of the following parameters.

[0251] - The period of the time slot containing PSFCH resources (i.e., the period of the PSFCH time axis resources). Figure 12 (N)

[0252] -Whether to bind HARQ-ACK / NACK information: In Figure 12 In this context, HARQ-ACK / NACK information corresponding to the PSSCH received by the V2X receiving UE in time slots 2, 3, 4 and 5 can be sent in time slot 8. The HARQ-ACK / NACK bits sent in time slot 8 can be values ​​determined by AND operation of the corresponding HARQ-ACK / NACK bits of the PSSCH received in time slots 2, 3, 4 and 5 (i.e., if any one is NACK, then it is determined as NACK).

[0253] - Whether to use and configure retransmission in units of CBG: When using retransmission in units of CBG, a TB can be split into two or more CBGs, and HARQ-ACK / NACK feedback can be in units of CBG. In this case, two or more bits of HARQ-ACK / NACK feedback information for a TB can be sent via PSFCH.

[0254] - Number of TBs included in PSSCH: When a PSSCH sends two TBs, the number of bits in the HARQ-ACK / NACK information can be two (when the above-mentioned retransmission in units of CBG is not used).

[0255] - The actual number of PSSCHs sent / received: Figure 12 The diagram illustrates HARQ-ACK / NACK feedback for PSSCHs received in time slots 2, 3, 4, and 5, transmitted in time slot 8. When the SL channel quality is poor, the receiving UE may fail to receive one or more PSSCHs in some cases. In this situation, the receiving UE can generate HARQ-ACK / NACK information based on the actual number of PSSCHs received.

[0256] - The timing relationship between the PSSCH reception time and the PSFCH transmission time, or the minimum signal processing time K for the UE to prepare for PSSCH processing and PSFCH transmission: Figure 12 In this scenario, assume K=3. It can be assumed that the receiving UE receiving the PSSCH has already received the PSSCH in time slot "n", and the PSFCH resource exists in time slot "n+x". In this case, the receiving UE sending the PSFCH can send the HARQ-ACK / NACK information for the aforementioned PSSCH via the PSFCH existing in time slot "n+x" using the smallest "x" value equal to or greater than K. In other words, it can be considered that... Figure 12The receiving UE receives the PSSCH in time slot 2 (n=2). Since the PSFCH resources exist in time slots 4 (n+x=4) and 8 (n+x=8), in the example above, x=2 (when n+x=4) or x=6 (when n+x=8). When assuming K=3, the receiving UE needs to use the smallest "x" value among integers equal to or greater than K=3; in the example above, the receiving UE can choose x=6 and send the PSFCH in time slot 8. As another example, one could consider... Figure 12 The receiving UE receives the PSSCH in time slot 1 (n=1). Since the PSFCH resource exists in time slots 4 (n+x=4) and 8 (n+x=8), in the example above, x=3 (when n+x=4) or x=7 (when n+x=8). When assuming K=3, the receiving UE needs to use the smallest "x" value among integers equal to or greater than K=3. In the example above, the receiving UE can choose x=3 and send the PSFCH in time slot 4.

[0257] The K value mentioned above can be determined by the SL UE through a combination of one or more of the following methods, or it can be configured through the base station's system information and RRC, or through PC-5 RRC.

[0258] - Method 1) K can be fixed regardless of the subcarrier size (e.g., K=2). This is why, considering the UE's processing time capability, a minimum processing time of more than 28 symbols may not be defined across all subcarrier intervals.

[0259] -Method 2) can determine K depending on the size of the subcarriers used. For example, K=2 for 15 kHz and 30 kHz, and K=3 for 60 kHz and 120 kHz.

[0260] - Method 3) K can be configured based on the SL resource pool or pre-configured based on the SL resource pool. As another example, it can be configured to vary depending on the unicast or multicast communication scheme in the SL resource pool.

[0261] -Method 4) is a method used to determine the process by a combination of one or more of the following a) to d), where a) to d) include, for example, UE processing capability and the time interval between PSSCH and PSFCH.

[0262] ■The time point at which PSSCH transmission ends, i.e., the time point of the last symbol.

[0263] ■The time point at which PSFCH transmission begins, i.e., the time point of the first symbol.

[0264] ■UE processing capabilities

[0265] ■Time Slot Boundary Point

[0266] The above method can be modified and applied as follows: When a PSSCH is received in time slot n, the receiving UE can send HARQ-ACK feedback information for the PSSCH through the earliest positioned PSFCH among the PSSCH and PSFCH with a time axis interval equal to or greater than y symbols. y can be a value pre-configured by the sending UE or a value configured in the SL resource pool for sending the corresponding PSSCH or PSFCH. For this configuration, the SL receiving UE can be required to exchange its processing capabilities with the SL sending UE, and furthermore, this configuration can vary depending on the subcarrier interval.

[0267] As another example, UE processing capabilities can be divided into two phases, such as normal processing capability (capability type 1) and enhanced processing capability (capability type 2), and can depend on the subcarriers to which different K values ​​are applied. More specifically, information about the UE processing capabilities of the SL transmitting / receiving UE can be exchanged during the RRC configuration process between the SL UE and the base station or during the establishment of a PC-5 RRC connection between SL UEs. As specified in Table 1, a UE with normal processing capability (capability type 1) can apply K=2 when the subcarrier spacing (SCS) used for SL transmitting / receiving is 15 kHz or 30 kHz, and a UE with enhanced processing capability (capability type 2) can apply K=1 when the subcarrier spacing (SCS) used for SL transmitting / receiving is 15 kHz or 30 kHz.

[0268] [Table 1]

[0269]

[0270] To illustrate the bit size of the HARQ-ACK / NACK information constituting the PSFCH, we can assume N=2 and K=1. In other words, it's the case where PSFCH resources are configured in the SL resource pool every N=2 time slots along the time axis, and the receiving UE has the capability (K=1) to send HARQ-ACK / NACK feedback information for the PSFCH received in time slot "n+1". In this case, it can be done as follows... Figure 13E The time slot shown is used to determine when HARQ-ACK feedback can actually be sent.

[0271] exist Figure 13EIn this context, the first line represents the logical index corresponding to the index of the time slots that constitute the SL resource pool. In this case, logical time slot indices are only assigned to time slots included in the SL resource pool, and not to time slots not included in the SL resource pool. In other words, since time slots 4, 8, 9, 10, 12, and 13 are not included in the SL resource pool, no logical time slot index is assigned. Figure 13E The second line shows the physical time slot index, and the time slot index can be assigned according to the order of the time slots, regardless of whether the corresponding time slot is included in the SL resource pool. Figure 13E The third line indicates whether the corresponding time slot is included in the SL resource pool. O means that the corresponding time slot is included in the SL resource pool, and X means that the corresponding time slot is not included in the SL resource pool. Figure 13E The fourth line indicates whether PSFCH transmission is possible, where O means a time slot where PSFCH transmission is possible and X means a time slot where PSFCH transmission is not possible. In this case, the time slots where PSFCH transmission is possible need to be included in the SL resource pool, and can be determined based on N calculated based on the logical time slot index, and it is assumed that N=2 (i.e., based on the logical time slot index, PSFCH resources can exist for every two time slots). Figure 13E The fifth line could indicate the time slot in which the PSSCH corresponding to the HARQ-ACK / NACK information sent via PSFCH is received. For example, the PSFCH sent in physical time slot index n could include HARQ feedback information about the PSSCHs received in time slots n-1 and n-2.

[0272] like Figure 13E As shown in the fifth line, the number of HARQ-ACK / NACK bits that each receiving UE can send on the PSFCH in a time slot where PSFCH transmission is possible can be 2 bits. In other words, each receiving UE can determine the number of HARQ-ACK / NACK feedback bits that need to be included in the PSFCH when transmitting PSFCH in a specific time slot, depending on the UE processing capability configuration or determined K, the period N for configuring PSFCH resources, the time slots where PSFCH resources exist, and the time slots included in the SL resource pool. More specifically, the determined number of HARQ-ACK / NACK feedback bits can be determined by the following equation (1).

[0273] The number of HARQ-ACK bits to be included in the PSFCH sent in physical time slot n = the number of time slots included in the SL resource pool from physical time slot (k-K+1) to physical time slot (nK)...(1)

[0274] In equation (1), the physical slot index k can be an index of a slot that includes a PSFCH resource configured immediately before the PSFCH that can be sent in physical slot n.

[0275] As another example, given N and K, the maximum number of HARQ-ACK feedback bits sent by a receiving UE on a PSFCH can be fixed (i.e., all receiving UEs send HARQ-ACK feedback including the same number of bits). This fixed number of feedback bits can be defined as the maximum number of HARQ-ACK feedback bits sent by a receiving UE in a PSFCH, and can be determined by the following equation (2).

[0276] The maximum number of HARQ-ACK / NACK feedback bits that a receiving UE can send on a single PSFCH is N + K - 1… (2)

[0277] As another example, when sending feedback in SL unicast or multicast communication, the number of feedback bits can be calculated using the number of time slots included in the SL resource pool, N, K, and the number of time slots that can send PSSCH associated with the HARQ-ACK feedback sent on the PSSCH in the time slot used for PSFCH transmission. In the example above, depending on the combination of N and K, the number of HARQ-ACK feedback bits sent by the receiving UE can increase to a predetermined value or more. In this case, the PSFCH reception error rate may increase because many bits need to be sent. Therefore, the receiving UE can send only the last K bits of the feedback bits that need to be sent by the receiving UE (i.e., only send HARQ-ACK / NACK feedback information about the most recently received PSSCH), without sending the remaining bits.

[0278] Meanwhile, PSFCH resources may exist in a specific time slot, but there may be no SL time slot where the PSSCH associated with HARQ-ACK / NACK feedback needs to be transmitted. In other words, depending on N and K and the SL resource pool configuration, there may be cases where the feedback information bits to be transmitted do not exist in the PSFCH resources of a specific time slot. In this case, even if the receiving UE has configured PSFCH resources in the corresponding time slot, the receiving UE can consider that PSFCH resources do not exist. In other words, although configured to allow the existence of PSFCH resources, the receiving UE can ignore the corresponding PSFCH resources and can choose not to perform PSFCH transmission. In this case, the receiving UE can perform the transmission / reception of control information and / or PSSCH in the corresponding time slot.

[0279] In this document, when describing HARQ-ACK / NACK, the corresponding PSSCH can be a unicast or multicast PSSCH configured or indicated to send HARQ-ACK / NACK. In other words, the proposed scheme may not be applicable to PSSCHs that do not require sending HARQ-ACK / NACK (i.e., PSSCHs without HARQ-ACK / NACK configuration). Furthermore, the control information scheduling the PSSCH can refer to the PSCCH, but this disclosure is not limited to this. In other words, control information can be sent not only via the PSSCH (e.g., via the PSSCH itself). Moreover, the control information can be a single control message, but multiple control messages can schedule a single PSSCH.

[0280] Figure 14 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0281] and Figure 10 different, Figure 14 This illustrates a scenario where the same TB is repeatedly transmitted through two or more time slots via time slot aggregation or blind retransmission. (See reference...) Figure 10 The above, Figure 14 This shows that the starting PRB index of the last PSSCH sent by the V2X transmitting UE (or the last PRB index of the last PSSCH) can be associated with the starting PRB index of the PSFCH sent by the V2X receiving UE.

[0282] More specifically, in Figure 14 In V2X, the transmitting UE can transmit PSCCH and PSSCH in time slot nK and repeat them in time slot n. The receiving UE can decode PSCCH to obtain SL control information and obtain information about the time / frequency / code resources of PSSCH. Furthermore, the receiving UE can obtain information about RV and New Data Indicator (NDI) from the SL control information. From this information, the receiving UE can determine whether a TB transmitted in time slot n is a new TB or a repeat of a TB transmitted in time slot nK.

[0283] In addition, V2X transmitting / receiving UEs can be configured with information regarding the number of aggregated time slots (when time slot aggregation is configured) or the maximum number of retransmissions (when blind retransmission is reconfigured). This information allows the V2X transmitting and receiving UEs to identify whether the time slot in which the last PSSCH of a specific TB is transmitted, or the PSSCH within the corresponding time slot, is the last time slot.

[0284] Therefore, as Figure 14As shown, when the starting PRB index of the PSSCH in time slot n is M, the starting PRB index of the PSFCH in time slot (n+L) can be the same M. As another example, when the starting PRB index of the PSSCH in time slot n is M, the PSFCH in time slot (n+L) can start at (M + offset) (or (M - offset)). In this case, the unit of offset can be PRB, and it can be a fixed value used the same by all V2X UEs or a value configured to vary for each resource pool. For example, in resource pool 1, 10 can be used as the offset value, and in resource pool 2, 20 can be used as the offset value.

[0285] Similar to the example above, the last PRB index of the PSSCH sent by the V2X transmitting UE in time slot n can be correlated with the starting PRB index of the PSFCH sent by the V2X receiving UE in time slot (n+L).

[0286] at the same time, Figure 14 This illustration shows the transmission of PSCCH and PSSCH in the same time slot, but this disclosure is not limited thereto. Information regarding the number of resource blocks constituting the PSFCH can be obtained using... Figure 10 At least one of the methods described herein.

[0287] Figure 14 This illustrates a PSSCH that is repeatedly transmitted over two or more time slots (repeated transmission via blind retransmission or repeated transmission via time slot aggregation). In this case, a PSCCH including control information about the corresponding PSSCH can be transmitted together in the time slot where the PSSCH is transmitted. Figure 14 In this context, because the starting PRB index of the last transmitted PSSCH is associated with the starting PRB index of the PSFCH, if the V2X receiving UE fails to decode the last PSSCH transmitted in slot n, the V2X receiving UE may not be able to obtain information about the starting PRB index of the PSFCH. To resolve this issue, the V2X receiving UE can determine the starting PRB index of the PSFCH by using the starting PRB index of the last PSSCH received by the V2X receiving UE (or successfully decoded by the V2X receiving UE).

[0288] Meanwhile, regardless of the number of time slots used for time slot aggregation or the number of repeated PSSCH transmissions, the PSSCH can always be positioned and transmitted at the same frequency. In this case, the V2X receiving UE can refer to any PSSCH in the PSSCH received by the V2X receiving UE (or successfully decoded by the V2X receiving UE) to determine the starting PRB index of the PSFCH from the starting PRB index of the PSSCH.

[0289] HARQ-ACK / NACK messages sent by a V2X receiving UE in multicast or unicast communication can be sent via one PSFCH resource or two PSFCH resources. When sending HARQ-ACK / NACK messages via one PSFCH, the following can be applied: Figure 14 The method described herein. However, when sending HARQ-ACK / NACK information through two PSFCH resources (i.e., one PSFCH resource is used for HARQ-ACK transmission and the other PSFCH resource is used for HARQ-NACK transmission), a method for indicating the starting point of the two PSFCH resources may be required.

[0290] When two PSFCH resources exist consecutively, such as Figure 14 As described above, the starting PRB index of the first PSFCH resource can be derived from the starting PRB index of the last PSSCH (or from the starting PRB index of the last PSSCH successfully received by the V2X UE). In other words, in the example, the starting PRB index of the first PSFCH resource can be M or (M + offset) (or (M - offset)). Furthermore, the starting PRB index of the second PSFCH resource can be determined depending on the number of PRBs constituting the first PSFCH resource. For example, if we assume the number of PRBs constituting the first PSFCH resource is [X1], then the starting PRB index of the second PSFCH resource can be M + [X1] or (M + offset + [X1]) (or (M - offset - [X1])). In this case, [X1] can be a fixed value or configured by the base station or the V2X-transmitted UE.

[0291] When the two PSFCH resources are not contiguous, such as Figure 14 As described, the starting PRB index of the first PSFCH resource can be derived from the starting PRB index of the last PSSCH (or from the starting PRB index of the last PSSCH successfully received by the V2X UE). The starting PRB index of the second PSFCH resource can be configured by a separate offset. For example, in the example, the starting PRB index of the first PSFCH resource can be M or (M + offset 1) (or (M - offset 1)). The starting PRB index of the second PSFCH resource can be (M + offset 2) or (M + offset 1 + offset 2) (or (M - offset 1 - offset 2)). In this case, offset 1 can mean the difference between the starting PRB index of the PSSCH and the starting PRB index of the PSFCH, and offset 2 can mean the difference between the starting PRB index of the first PSFCH resource and the starting PRB index of the second PSFCH resource.

[0292] As another example, the starting PRB index of the second PSFCH resource can be (M + [X1] + offset 2) or (M + offset 1 + [X1] + offset 2) (or (M - offset 1 - [X1] - offset 2)). In this case, [X1] means the number of PRBs constituting the first PSFCH resource, and [X1] can be a fixed value or configured by the base station or V2X transmitted to the UE. Additionally, in this example, offset 1 can mean the difference between the starting PRB index of the PSSCH and the starting PRB index of the PSFCH. Furthermore, offset 2 can mean the difference between the starting PRB index of the first PSFCH resource and the starting PRB index of the second PSFCH resource.

[0293] Although not in Figure 14 As described in the text, but Figure 13B , Figure 13C and Figure 13D One of the methods described in [the document] can be applied to [the following]. Figure 14 .

[0294] Figure 15 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0295] and Figure 10 and Figures 11 to 14 different, Figure 15 This illustrates the case of repeated PSFCH transmissions. This situation could be identical, as the starting PRB index (or last PRB index) of the PSFCH can be represented by a reference. Figures 10 to 14 One of the methods described is to initially send the starting PRB index of the PSFCH.

[0296] exist Figure 15 In this context, it can be assumed that the V2X transmitting UE used to receive the PSFCH and the V2X receiving UE used to transmit the PSFCH previously knew the number of PSFCH retransmissions. For example, the number of PSFCH retransmissions can be included in the resource pool configuration information and can be configured by the base station, or it can be pre-configured when no base station exists.

[0297] Therefore, one of the following methods can be used as a method for configuring the starting PRB index of the Xth PSFCH to be sent (where X is an integer greater than 1).

[0298] For example, the same PRB index as the starting PRB index of the initially sent PSFCH can be used. As another example, if an offset has already been applied to determine the starting PRB index of the initially sent PSFCH, the same corresponding offset can be applied. More specifically, when the starting PRB index of the initially sent PSFCH is (M + offset) (or (M - offset)), the starting PRB index of the second sent PSFCH can be (M + offset + offset) (or (M - offset - offset)). In the examples above, M means either the starting PRB index or the last PRB index of the PSFCH.

[0299] As another example, different offset values ​​can be used for each PSFCH transmission. In other words, when the starting PRB index of the initially transmitted PSFCH is (M + offset 1) (or (M - offset 1)), the starting PRB index of the second transmitted PSFCH can be (M + offset 1 + offset 2) (or (M - offset 1 - offset 2)). In this case, offset 1 and offset 2 can be configured by the base station, or they can be pre-configured if the base station does not exist.

[0300] The same number of PRBs constituting the PSFCH can be used for both the initial transmission and retransmission of the PSFCH. As another example, the number of PRBs used for the initial transmission of the PSFCH and the number of PRBs used for the retransmission can be different. For instance, when the number of PRBs used for the initial transmission is Y1, the number of PRBs for the second transmission of the PSFCH can be (Y1 + Z1). In this case, Z1 can be a fixed value or configured or pre-configured by the base station. The number of PRBs for the third transmission of the PSFCH can be (Y1 + Z1 + Z2). In this case, Z2 can be the same value as Z1 or a different value. Again, Z2 can be a fixed value or configured or pre-configured by the base station. The above method can also be applied to the number of PRBs for the fourth transmission of the PSFCH.

[0301] Although not in Figure 15 As described in the text, but Figure 13B , Figure 13C and Figure 13D One of the methods described in [the document] can be applied to [the following]. Figure 15 .

[0302] Figure 16 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0303] Figure 10 This shows the association between PSSCH frequency resources and PSFCH frequency resources. However, with Figure 10 different, Figure 16The PSCCH frequency resources are shown to be associated with the PSFCH frequency resources.

[0304] like Figure 16 As shown, a V2X transmitting UE can transmit PSCCH and PSSCH in time slot nK. A V2X receiving UE can decode PSCCH to obtain SL control information and information about the time / frequency / code resources of PSSCH. Figure 16 The illustration shows the transmission of PSCCH and PSSCH in the same time slot, but this disclosure is not limited thereto. In other words, PSCCH can be transmitted in time slot nK, but PSSCH can be transmitted in a subsequent time slot. In this case, the timing relationship between PSCCH and PSSCH can be fixed (e.g., PSSCH is transmitted 4 ms after PSCCH reception) or can be configured by the base station. As another example, the V2X transmitting UE can indicate the timing relationship between PSCCH and PSSCH in the SL control information transmitted by the V2X transmitting UE. The V2X receiving UE, having already obtained the SL control information, can decode PSSCH using information about the frequency / code resources of PSSCH and the timing relationship between PSCCH and PSSCH.

[0305] The starting PRB index of a PSCCH transmitted by a V2X transmitting UE in slot (nK) can be related to the starting PRB index of a PSFCH transmitted by a V2X receiving UE in slot n. For example, if the starting PRB index of the PSCCH in slot (nK) is M, the starting PRB index of the PSFCH in slot n can also be the same M. As another example, if the starting PRB index of the PSCCH in slot (nK) is M, the PSFCH in slot n can start at (M + offset) (or (M - offset)). In this case, the unit of offset can be PRB, and it can be a fixed value used the same by all V2X UEs or a value configured to vary for each resource pool. For example, in resource pool 1, 10 can be used as the offset value, and in resource pool 2, 20 can be used as the offset value.

[0306] Similar to the example above, the last PRB index of the PSCCH sent by the V2X-transmitting UE in time slot (nK) can be correlated with the starting PRB index of the PSFCH sent by the V2X-receiving UE in time slot n.

[0307] For information regarding the number of resource blocks that make up the PSFCH, please refer to Figures 8 and 9. Figure 10 At least one of the methods described herein.

[0308] Figure 16The example shown illustrates the transmission of one SL control message in a single time slot; however, it is possible to transmit two SL control messages in a single time slot. For instance, when the SL control message is split into two groups, the first SL control message may include basic information (e.g., information related to sensing operations and destination ID), and may also include time / frequency / code resource allocation information for decoding the second SL control message. The second SL control message may include time / frequency / code resource allocation information for decoding the SL data channel. In this case, the starting PRB index of the PSFCH may be associated with the starting PRB index (or the last PRB index) of the PSCCH that transmitted the first SL control message. As another example, the starting PRB index of the PSFCH may be associated with the starting PRB index (or the last PRB index) of the PSCCH that transmitted the second SL control message.

[0309] HARQ-ACK / NACK messages sent by a V2X receiving UE in multicast or unicast communication can be sent via one PSFCH resource or two PSFCH resources. When sent via one PSFCH resource, the method described above can be applied. However, when sent via two PSFCH resources (i.e., one PSFCH resource for HARQ-ACK transmission and another for HARQ-NACK transmission), a method for indicating the starting points of the two PSFCH resources may be required.

[0310] When two PSFCH resources exist consecutively, the starting PRB index of the first PSFCH resource can be derived from the starting PRB index of the PSCCH as described above. In other words, in the example, the starting PRB index of the first PSFCH resource can be M or (M + offset) (or (M - offset)). Furthermore, the starting PRB index of the second PSFCH resource can be determined depending on the number of PRBs constituting the first PSFCH resource. For example, if we assume the number of PRBs constituting the first PSFCH resource is [X1], then the starting PRB index of the second PSFCH resource can be (M + [X1]) or (M + offset + [X1]) (or (M - offset - [X1])). In this case, [X1] can be a fixed value, or it can be configured by the base station or V2X transmitted to the UE.

[0311] When two PSFCH resources are not contiguous, the starting PRB index of the first PSFCH resource can be derived from the starting PRB index of the PSCCH, and the starting PRB index of the second PSFCH resource can be configured using separate offsets as described above. For example, in the example, the starting PRB index of the first PSFCH resource can be M or (M + offset 1) (or (M - offset 1)). The starting PRB index of the second PSFCH resource can be (M + offset 2) or (M + offset 1 + offset 2) (or (M - offset 1 - offset 2)). In this case, offset 1 can represent the difference between the starting PRB index of the PSCCH and the starting PRB index of the PSFCH, and offset 2 can represent the difference between the starting PRB index of the first PSFCH resource and the starting PRB index of the second PSFCH resource.

[0312] As another example, the starting PRB index of the second PSFCH resource can be (M + [X1] + offset 2) or (M + offset 1 + [X1] + offset 2) (or (M - offset 1 - [X1] - offset 2)). In this case, [X1] means the number of PRBs constituting the first PSFCH resource, and [X1] can be a fixed value or can be configured by the base station or V2X transmitted to the UE. Additionally, in this example, offset 1 can mean the difference between the starting PRB index of the PSCCH and the starting PRB index of the PSFCH. Furthermore, offset 2 can mean the difference between the starting PRB index of the first PSFCH resource and the starting PRB index of the second PSFCH resource.

[0313] Although not in Figure 16 As described in the text, but Figure 13B , Figure 13C and Figure 13D One of the methods described in [the document] can be applied to [the following]. Figure 16 .

[0314] Figure 17 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0315] Figure 17 This illustrates the case where the starting PRB index of the PSCCH sent by different V2X transmitting UEs is the same. In other words, this means the starting PRB index of the PSCCH sent by V2X transmitting UE 1 to V2X receiving UE 1 in time slot (nK) is the same as the starting PRB index of the PSCCH sent by V2X transmitting UE 2 to V2X receiving UE 2 in time slot (n-K+1). Because the PSCCHs sent in different time slots use the same starting PRB index, if a reference is applied... Figure 16The described method assumes that the starting PRB index of the PSFCH is the same, and therefore conflicts may occur between PSFCHs. Figure 17 As shown, this problem can occur not only when different V2X transmitting UEs send PSCCH to different V2X receiving UEs, but also when different V2X transmitting UEs send PSCCH to the same V2X receiving UE (i.e., when a PSCCH / PSSCH sent by V2X transmitting UE 1 and a PSCCH / PSSCH sent by V2X transmitting UE 2 are sent to V2X transmitting UE 1). This PSCCH conflict problem can be resolved using one of the following methods.

[0316] Method 1) The starting PRB index of PSCCH and the V2X UE ID indicate the starting PRB index of PSFCH.

[0317] Method 1-1) Using the source ID

[0318] Method 1-2) Using Destination ID

[0319] Method 2) The starting PRB index of PSCCH and the index of the time slot for sending PSSCH indicate the starting PRB index of PSFCH.

[0320] The specific operation of the above method and Figure 11 The operations described herein are the same.

[0321] Although not in Figure 17 As described in the text, but Figure 13B , Figure 13C and Figure 13D One of the methods described in [the document] can be applied to [the following]. Figure 17 .

[0322] Figure 18 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0323] and Figure 16 and Figure 17 different, Figure 18 This illustrates a scenario where the same TB is repeatedly transmitted through two or more time slots via time slot aggregation or blind retransmission. (As combined with...) Figure 16 The above, Figure 18 This shows that the starting PRB index of the last PSCCH sent by the V2X transmitting UE (or the last PRB index of the last PSCCH) can be associated with the starting PRB index of the PSFCH sent by the V2X receiving UE.

[0324] More specifically, in Figure 18In V2X, the transmitting UE can transmit PSCCH and PSSCH in time slot (nK) and repeat PSCCH and PSSCH in time slot n. The receiving UE can decode PSCCH to obtain SL control information and information about the time / frequency / code resources of PSSCH. Furthermore, the receiving UE can obtain information about RV and NDI from the SL control information. From this information, the receiving UE can identify whether a TB transmitted in time slot n is a new TB or a repeat of a TB transmitted in time slot (nK).

[0325] Additionally, V2X transmitting / receiving UEs can be configured with information regarding the number of aggregated time slots (when time slot aggregation is configured) or the maximum number of retransmissions (when blind retransmission is reconfigured). This information allows the V2X transmitting and receiving UEs to identify whether the time slot in which the last PSSCH of a specific TB is transmitted, or the PSSCH within the corresponding time slot, is the last time slot.

[0326] Therefore, as Figure 18 As shown, when the starting PRB index of the PSCCH in time slot n is M, the starting PRB index of the PSFCH in time slot (n+L) can also be the same M. As another example, when the starting PRB index of the PSCCH in time slot n is M, the PSFCH in time slot (n+L) can start at (M + offset) (or (M - offset)). In this case, the unit of offset can be PRB, and it can be a fixed value used identically by all V2X UEs or a value configured to vary for each resource pool. For example, in resource pool 1, 10 can be used as the offset value, and in resource pool 2, 20 can be used as the offset value.

[0327] Similar to the example above, the last PRB index of the PSCCH sent by the V2X transmitting UE in time slot n can be correlated with the starting PRB index of the PSFCH sent by the V2X receiving UE in time slot (n+L).

[0328] at the same time, Figure 18 This illustration shows the transmission of PSCCH and PSSCH in the same time slot, but this disclosure is not limited thereto. Information regarding the number of resource blocks constituting the PSFCH can be obtained using... Figure 10 , Figure 11 , Figure 14 and Figure 15 At least one of the methods described herein.

[0329] Figure 18This illustrates a PSSCH that is repeatedly transmitted over two or more time slots (repeated transmission via blind retransmission or repeated transmission via time slot aggregation). In this case, a PSCCH including control information about the corresponding PSSCH can be transmitted together in the time slot where the PSSCH is transmitted. Figure 12 In this context, because the starting PRB index of the last PSCCH transmitted is associated with the starting PRB index of the PSFCH, if the V2X receiving UE fails to decode the last PSCCH transmitted in slot n, the V2X receiving UE may not be able to obtain information about the starting PRB index of the PSFCH. To resolve this issue, the V2X receiving UE can determine the starting PRB index of the PSFCH by using the starting PRB index of the last PSCCH received (or successfully decoded) by the V2X receiving UE.

[0330] Meanwhile, regardless of the number of time slots used for time slot aggregation or the number of repeated transmissions of PSSCH, PSCCH can always be transmitted at the same frequency. In this case, the V2X receiving UE can refer to any PSCCH received (or successfully decoded) by the V2X receiving UE to determine the starting PRB index of PSFCH from the starting PRB index of PSCCH.

[0331] HARQ-ACK / NACK messages sent by a V2X receiving UE in multicast or unicast communication can be sent via one PSFCH resource or two PSFCH resources. When sending HARQ-ACK / NACK messages via one PSFCH resource, the method described above can be applied. However, when sending HARQ-ACK / NACK messages via two PSFCH resources (i.e., one PSFCH resource is used for HARQ-ACK transmission, and the other for HARQ-NACK transmission), a method for indicating the starting points of the two PSFCH resources may be required.

[0332] When two PSFCH resources exist consecutively, the starting PRB index of the first PSFCH resource can be derived from the starting PRB index of the PSSCH as described above. In other words, in the example, the starting PRB index of the first PSFCH resource can be M or (M + offset) (or (M - offset)). Furthermore, the starting PRB index of the second PSFCH resource can be determined depending on the number of PRBs constituting the first PSFCH resource. For example, if we assume the number of PRBs constituting the first PSFCH resource is [X1], then the starting PRB index of the second PSFCH resource can be (M + [X1]) or (M + offset + [X1]) (or (M - offset - [X1])). In this case, [X1] can be a fixed value or configured by the base station or V2X transmitted to the UE.

[0333] When two PSFCH resources are not contiguous, the starting PRB index of the first PSFCH resource can be derived from the starting PRB index of the PSCCH, and the starting PRB index of the second PSFCH resource can be configured using separate offsets as described above. For example, in the example, the starting PRB index of the first PSFCH resource can be M or (M + offset 1) (or (M - offset 1)). The starting PRB index of the second PSFCH resource can be (M + offset 2) or (M + offset 1 + offset 2) (or (M - offset 1 - offset 2)). In this case, offset 1 can represent the difference between the starting PRB index of the PSCCH and the starting PRB index of the PSFCH, and offset 2 can represent the difference between the starting PRB index of the first PSFCH resource and the starting PRB index of the second PSFCH resource.

[0334] As another example, the starting PRB index of the second PSFCH resource can be (M + [X1] + offset 2) or (M + offset 1 + [X1] + offset 2) (or (M - offset 1 - [X1] - offset 2)). In this case, [X1] means the number of PRBs constituting the first PSFCH resource, and [X1] can be a fixed value or configured by the base station or V2X transmitted to the UE. Furthermore, in this example, offset 1 can mean the difference between the starting PRB index of the PSCCH and the starting PRB index of the PSFCH. Additionally, offset 2 can mean the difference between the starting PRB index of the first PSFCH resource and the starting PRB index of the second PSFCH resource.

[0335] Although not in Figure 18 As described in the text, but Figure 13B , Figure 13C and Figure 13D One of the methods described in [the document] can be applied to [the following]. Figure 18 .

[0336] Figure 19 This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0337] and Figure 16 , Figure 17 and Figure 18 different, Figure 19 The example of repeatedly sending PSFCH is shown. This situation can be the same because the starting PRB index (or the last PRB index) of PSCCH can be represented by a reference. Figure 16 , Figure 17 and Figure 18 One of the methods described is to initially send the starting PRB index of the PSFCH.

[0338] exist Figure 19 In this context, it can be assumed that the V2X transmitting UE used to receive the PSFCH and the V2X receiving UE used to transmit the PSFCH previously knew the number of PSFCH retransmissions. For example, the number of PSFCH retransmissions can be included in the resource pool configuration information and can be configured by the base station, or it can be pre-configured when no base station exists.

[0339] Therefore, one of the following methods can be used as a method for configuring the starting PRB index of the Xth PSFCH to be sent (where X is an integer greater than 1).

[0340] For example, the same PRB index as the starting PRB index of the initially sent PSFCH can be used. As another example, if an offset has already been applied to determine the starting PRB index of the initially sent PSFCH, the same corresponding offset can be applied. More specifically, when the starting PRB index of the initially sent PSFCH is (M + offset) (or (M - offset)), the starting PRB index of the second sent PSFCH can be (M + offset + offset) (or (M - offset - offset)). In the examples above, M means either the starting PRB index or the last PRB index of the PSCCH.

[0341] As another example, different offset values ​​can be used for each PSFCH transmission. In other words, when the starting PRB index of the initially transmitted PSFCH is (M + offset 1) (or (M - offset 1)), the starting PRB index of the second transmitted PSFCH can be (M + offset 1 + offset 2) (or (M - offset 1 - offset 2)). In this case, offset 1 and offset 2 can be configured by the base station, or they can be pre-configured if the base station does not exist.

[0342] The same number of PRBs constituting the PSFCH can be used for both the initial transmission and retransmission of the PSFCH. As another example, the number of PRBs used for the initial transmission of the PSFCH and the number of PRBs used for the retransmission can be different. For instance, when the number of PRBs used for the initial transmission is Y1, the number of PRBs for the second transmission of the PSFCH can be (Y1 + Z1). In this case, Z1 can be a fixed value, or it can be a value configured or pre-configured by the base station. The number of PRBs for the third transmission of the PSFCH can be (Y1 + Z1 + Z2). In this case, Z2 can be the same value as Z1 or it can be a different value. Again, Z2 can be a fixed value, or it can be a value configured or pre-configured by the base station. The above method can also be applied to the number of PRBs for the fourth transmission of the PSFCH.

[0343] Figure 10 , Figure 11 , Figure 14 , Figure 15 , Figure 16 , Figure 17 , Figure 18 and Figure 19 The index of the starting PRB described herein can mean either the starting index of a subchannel or the lowest CCE index. In this case, a subchannel means either a set of consecutive PRBs or a set of non-consecutive PRBs, and can be interpreted as a resource block group (RBG). Furthermore, a CCE means a control channel element that constitutes a control channel, and a CCE can include N PRBs. In this case, N can be an integer greater than 1.

[0344] exist Figure 10 , Figure 11 , Figure 14 , Figure 15 , Figure 16 , Figure 17 , Figure 18 and Figure 19 The document describes a method for allocating PSFCH frequency resources using the starting PRB index and the number of PRBs constituting the PSFCH. However, when the number of PRBs constituting the PSFCH is always fixed, PSFCH frequency resources can be allocated using either the starting PRB index or the last PRB index. In this case, the starting PRB index can be interpreted as either the starting index of the subchannel or the lowest CCE index.

[0345] Although not in Figure 19 As described in the text, but Figure 13B , Figure 13C and Figure 13D One of the methods described in [the document] can be applied to [the following]. Figure 19 .

[0346] Figure 20A This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment. Figure 20B This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0347] Figure 20A and Figure 20B Showing more details Figure 13B , Figure 13C and Figure 13D And in Figure 20A and Figure 20B In this context, M represents the number of sub-channels constituting a sidelink BWP or SL bandwidth within the SL bandwidth. In this case, a PSSCH sub-channel may include one or more frequency blocks (RBs), and as follows: Figure 13B and Figure 13CThe number of RBs constituting a PSSCH subchannel, as defined in [the document], can be defined as β. In this case, β can have a value of 10, 15, 20, 50, 75, or 100, and can be obtained by receiving resource pool information from the SL UE (in other words, information about the number of RBs constituting a PSSCH subchannel can be included in the resource pool configuration information), such as... Figures 6 to 7 As stated in [the text]. Additionally, as [the text continues with further details]. Figure 13B and Figure 13C The number of RBs constituting a PSFCH sent by a receiving UE, as defined in the document, can be defined as γ. γ can be one of 1 or an integer greater than 1 (e.g., 2, 4, etc.) and can be configured in the SL resource pool information, such as β, or unlike β, can always use a fixed value in all resource pools without separate configuration (e.g., the value is fixed at γ=1 in all resource pools).

[0348] Additionally, as referenced Figure 12 , Figure 13B , Figure 13C and Figure 13D As described, PSFCH transmit resources (or PSFCH receive resources, hereinafter referred to as PSFCH resources) can exist every N time slots, where N can be one of 1, 2, and 4. For example, N=1 can mean that PSFCH resources exist for every SL time slot, and N=2 and N=4 can mean that PSFCH resources exist for every two SL time slots (N=2) and for every four SL time slots (N=4), respectively. Furthermore, as referenced... Figure 12The minimum difference between the time point when the receiving UE receives the PSCCH / PSSCH from the sending UE and the time point when the receiving UE sends the PSFCH to the sending UE can be defined as K time slots. This can mean the minimum time interval required for the receiving UE to receive SL control information (PSCCH), decode SL data (PSSCH), and prepare to send the SL feedback channel. In other words, considering the UE's signal processing capabilities, K may need to be determined with sufficient margin. For example, K can be one of 1, 2, and 3, and K=1 can be supported by UEs with fast signal processing capabilities (i.e., high signal processing capabilities), and K=3 can be supported by UEs with slow signal processing capabilities (i.e., low signal processing capabilities). K=1 can mean that when the receiving UE receives the PSCCH / PSSCH in SL time slot index n, the receiving UE needs to send the PSFCH in a time slot after SL time slot index (n+1). Furthermore, K=2 and K=3 can mean that when the receiving UE receives PSCCH / PSSCH in SL slot index n, the receiving UE needs to send PSFCH in the slot after slot index (n+2) (K=2) and the slot after SL slot index (n+3) (K=3).

[0349] The values ​​N and K mentioned above can be configured for each SL resource pool, and N and K can also be configured with different values ​​for each resource pool. For example, in resource pool 1, N=N1 and K=K1, and in resource pool 2, N=N2 and K=K2. In this case, N1 and N2 can be the same or different, and K1 and K2 can be the same or different. When the SL UE is within the coverage of the base station, the SL UE can be configured with corresponding information from the base station through system information and RRC. When there is no base station coverage, N and K included in the pre-configured resource pool information can be used. When N and K are not included in the resource pool configuration information, the transmitting UE and receiving UE that want to perform SL transmission or reception in the corresponding resource pool can not operate SL HARQ in the corresponding resource pool.

[0350] Simultaneously, the two UEs performing unicast communication can negotiate their signal processing capabilities, and Figure 3The PC5-RRC connection establishment process described herein uses a K value corresponding to the negotiation result. For example, it can be assumed that UE-A and UE-B, which are to perform unicast communication, have fast signal processing capabilities (capability A or signal processing A1) and slow signal processing capabilities (capability B or signal processing time B1). When a resource pool capable of performing unicast communication can be configured, and two or more K values ​​are configured in the corresponding resource pool, UE-A and UE-B can negotiate to perform unicast communication using a K value greater than the slowest signal processing capability (capability B or signal processing time B1). As another example, when two or more resource pools capable of performing unicast communication are configured, and one K value is configured in each resource pool, UE-A and UE-B can negotiate to perform unicast communication in a resource pool configured with a K value greater than the slowest signal processing capability (capability B or signal processing time B1). In the above examples, multiple K values ​​can exist that satisfy the slowest signal processing capability (capability B or signal processing time B1) of UE-A and UE-B. In this scenario, the UE can negotiate to use the smallest K value among multiple K values ​​to perform unicast communication. As another example, when two or more resource pools capable of performing unicast communication are configured, and two or more K values ​​are configured in each resource pool, the UE can negotiate to use the K value that satisfies the slowest signal processing capability (capability B or signal processing time B1) of UE-A and UE-B to perform unicast communication. In this case, when multiple K values ​​exist that satisfy the slowest signal processing capability (capability B or signal processing time B1) of UE-A and UE-B, the UE can negotiate to use the smallest K value among the multiple K values ​​to perform unicast communication.

[0351] Figure 20A and Figure 20BAn example is shown where N=4 and K=1 are configured in the SL resource pool information. A receiving UE-A that has already received PSCCH / PSSCH in SL slot index 0 can send PSFCH in slots following SL slot index 1 (K=1). In this case, since PSFCH resources only exist in slot index 4 (N=4), receiving UE-A can send PSFCH in slot index 4. As another example, a receiving UE-B that has already received PSCCH / PSSCH in SL slot index 1 can send PSFCH in slots following SL slot index 2 (K=1). In this case, since PSFCH resources only exist in slot index 4 (N=4), receiving UE-B can send PSFCH in slot index 4 like receiving UE-A. As another example, a receiving UE-C that has already received PSCCH / PSSCH in slot index 2 can send PSFCH in slots following SL slot index 3 (K=1). In this scenario, since the PSFCH resource exists only in slot index 4 (N=4), receiving UE-C can send the PSFCH in slot index 4 just like receiving UE-A and receiving UE-B. As another example, receiving UE-D, which has already received PSCCH / PSSCH in slot index 3, can send the PSFCH in a slot after slot index 4 (K=1). In this case, since the PSFCH resource exists only in slot index 4 (N=4), receiving UE-D can send the PSFCH in slot index 4 just like receiving UE-A, receiving UE-B, and receiving UE-C.

[0352] As mentioned above, PSFCH resources do not exist in slot indices 0, 1, 2 and 3, and PSFCH resources may exist only in slot index 4. Figure 20A and Figure 20B This shows that the PSFCH symbols present in slot index 4 (when the PSFCH consists of one symbol) or PSFCH symbols (when the PSFCH consists of two or more symbols) are located in the SL bandwidth or the entire SL BWP within the SL bandwidth. Therefore, the (multiple) PSFCH symbols on the frequency axis can include (M×β) RBs. The number of (multiple) symbols constituting the PSFCH on the time axis can be included as follows: Figure 9A and Figure 9B The resource pool information described herein can be configured explicitly or implicitly. When the number (such as 1, 2, or 3) of the symbols constituting the PSFCH is explicitly configured in the resource pool information, the structure of the PSFCH transmitted by a receiving UE can be as follows: Figure 9A and Figure 9BAs shown. The number of symbols constituting a PSFCH can be implicitly configured in the resource pool information by whether or not the PSFCH is repeatedly transmitted, or the number of times it is repeatedly transmitted. For example, if the default number of PSFCH symbols on the timeline is defined as 1, then if repeated transmission is configured in the resource pool information, it means that the number of PSFCH symbols transmitted by the receiving UE in the corresponding resource pool is 2. If repeated transmission is not configured in the resource pool information, it means that the number of PSFCH symbols transmitted by the receiving UE in the corresponding resource pool is 1. Similarly, if the number of PSFCH symbols on the timeline is defined as 2, then if repeated transmission is configured in the resource pool information, it means that the number of PSFCH symbols transmitted by the receiving UE in the corresponding resource pool is 4. If repeated transmission is not configured in the resource pool information, it means that the number of PSFCH symbols transmitted by the receiving UE in the corresponding resource pool is 2. As another example, if the default number of PSFCH symbols on the timeline is defined as 1, and the number of repeated transmissions is configured as 2 in the resource pool information, it means that the receiving UE transmits 2 PSFCH symbols in the corresponding resource pool. Conversely, if the number of repeated transmissions is configured as 4 in the resource pool information, it means that the receiving UE transmits 4 PSFCH symbols in the corresponding resource pool. If repeated transmissions are not configured in the resource pool information or the number of repeated transmissions is configured as 0, it means that the receiving UE transmits 1 PSFCH symbol in the corresponding resource pool.

[0353] It is also possible to consider the case where (multiple) PSFCH symbols are located on the frequency axis within a portion of the SL bandwidth or SL BWP. Furthermore, slot 4 may include, as in the reference... Figure 7 The GAP as described.

[0354] As mentioned above, it has already been Figure 20A and Figure 20B A receiving UE that receives PSCCH and PSSCH in at least one of time slots in time slot indices 0, 1, 2, and 3 can send SL HARQ feedback to the transmitting UE using at least one of the PSFCH resources configured in time slot 4. In this case, it is possible to apply Figure 13B , Figure 13C and Figure 13DThe diagram illustrates the mapping relationship between PSSCH and PSFCH resources (or the mapping relationship between PSCCH and PSFCH resources). In other words, the receiving UE can obtain the location (or the starting point) of the PSFCH frequency resource to be transmitted by the receiving UE through a combination of the index of the time slot for receiving PSSCH and the start index of the sub-channel for receiving PSSCH. Similarly, the transmitting UE can obtain information about the location (or the starting point) of the PSFCH frequency resource to be received by the transmitting UE through a combination of the index of the time slot for transmitting PSSCH and the start index (or the index of the starting sub-channel) for transmitting PSSCH.

[0355] Reference Figure 13B , Figure 13C and Figure 13D The mapping relationship described above between PSSCH and PSFCH resources, or between PSSCH and PSFCH resources, has already described how the time slot index and the starting sub-channel index of the PSSCH can be associated with the location of the PSFCH frequency resource to be actually transmitted (or actually received). More generally, as... Figure 20A and Figure 20B As shown, the slot index and starting subchannel index of the PSSCH can be associated with the starting point of a candidate PSFCH resource that includes one or more PSFCH frequency resources, rather than with the location (or starting point) of the PSFCH frequency resource to be actually transmitted (or actually received). In this case, if the number of PSFCH candidates is 1, then refer to Figure 13B , Figure 13C and Figure 13D The mapping relationships described above between PSSCH resources and PSFCH frequency resources, or between PSSCH resources and PSFCH frequency or code (or frequency and code) resources, can be the same. Conversely, if there are two or more PSFCH candidates, the time and frequency resources of one PSSCH can be associated with the frequency or code (or frequency and code) resources of multiple PSFCH candidates.

[0356] More specifically, such as Figure 20AAs shown, a set of candidate PSFCH frequency resources including Δ PSFCH resources can be considered. For ease of description, candidate PSFCH frequency resources including PSFCH frequency resource indices 0 to (Δ-1) can be defined as candidate PSFCH frequency resource set index 0. Candidate PSFCH frequency resources including PSFCH frequency resource indices Δ to (2Δ-1) can be defined as candidate PSFCH frequency resource set index 1. Generally, there can exist a total of ((M×β) / ᝛�) candidate PSFCH frequency resource sets including Δ PSFCH resources, and the slowest (or highest) frequency can be referenced from index 0 to index ((M×β) / ᝛�-1). However, such indices are examples and are not provided in the original text. Figure 13B , Figure 13C and Figure 13D As described, depending on the configured (or pre-configured or fixed) offset value, the starting index of the candidate PSFCH frequency resource set may not be 0. For example, when the offset is 3, the set of candidate PSFCH frequency resources constituting indices 3Δ to (3Δ-1) may correspond to candidate PSFCH frequency resource set index 0.

[0357] The starting index (or index of the candidate starting PSFCH frequency resource), PSSCH slot index, and starting sub-channel index (or starting index of the sub-channel) of the aforementioned candidate PSFCH frequency resource set can have the following correlation: A PSSCH received in the starting sub-channel index m (or starting index m of the sub-channel) of slot index 1 can represent the starting point of a candidate PSFCH frequency resource set including Δ PSFCH candidates. For example, according to reference... Figure 13B The mapping relationship between the described PSSCH resources and PSFCH frequency resources is in Figure 20A A PSSCH transmitted in the starting sub-channel index 0 (or the starting index 0 of the sub-channel) of time slot index 0 can represent candidate PSFCH frequency resource set index 0, which includes PSFCH frequency resource indices 0 to (Δ-1) in time slot index 4. A PSSCH transmitted in the starting sub-channel index 1 (or the starting index 1 of the sub-channel) of time slot index 0 can represent candidate PSFCH frequency resource set index 1, which includes PSFCH frequency resource indices Δ and (2Δ-1) in time slot index 4.

[0358] In the examples above, it has been described that the PSSCH slot index 0 and the starting sub-channel index 0 (or the starting index 0 of the sub-channel) are associated with the candidate PSFCH frequency resource set index 0. However, as mentioned above, depending on the configured (or pre-configured or fixed) offset values, the PSSCH slot index 0 and the starting sub-channel index 0 (or the starting index 0 of the sub-channel) can be associated with the candidate PSFCH frequency resource set index Q. Generally, this can mean that the PSSCH slot index 1 and the starting sub-channel index m (or the starting index m of the sub-channel) can be associated with the candidate PSFCH frequency resource set index δ. In this case, as mentioned above, there can be Δ candidate PSFCH frequency resources in the candidate PSFCH frequency resource set with index δ. The value Δ can be included in the resource pool information configured by the base station through RRC or system information. In the absence of coverage outside the base station, the value Δ can be included in the pre-configured resource pool information.

[0359] Meanwhile, the Δ value, which represents the PSFCH frequency resources constituting a candidate PSFCH frequency resource set, can always be a fixed value instead of being included in the resource pool configuration information. For example, the Δ value can be defined as a function of β (the number of RBs constituting a PSSCH subchannel) and γ (the number of RBs constituting a PSFCH used by a UE to transmit or receive a PSFCH). For example, ∥ = floor(β / γ) can be defined, and in this case, floor() can be a function that means rounding down to the decimal point. As another example, ∥ = ceil(β / γ) can be defined, and in this case, ceil() can be a function that means rounding up to the decimal point. In this case, the separate signaling used to configure the Δ value in the resource pool information can be omitted.

[0360] Figure 20A This illustrates that PSFCH frequency resources constituting a candidate PSFCH frequency resource set are located consecutively within that set. Conversely, Figure 20B This illustrates the non-contiguous location of PSFCH frequency resources constituting a candidate PSFCH frequency resource set within that set. For example, in... Figure 20B In this context, Δ PSFCH frequency resources with PSFCH frequency resource indices 0, n, 2n, ..., (Δ-n) can constitute a candidate PSFCH frequency resource set. In this case, each PSFCH frequency resource can have an offset "n" that can be configured in the resource pool information. When the offset n=1, Figure 20B Can be with Figure 20A Same. Therefore, Figure 20A The various embodiments described herein can also be applied to Figure 20B.

[0361] exist Figure 20A and Figure 20B In this context, a receiving UE, having determined the index of a candidate PSFCH frequency resource set comprising Δ PSFCH frequency resources through the PSSCH slot index and the index of the starting sub-channel (or the starting index of the sub-channel), can transmit a PSFCH to a transmitting UE using at least one of the Δ PSFCH frequency resources. In this case, various methods may exist for the receiving UE to select PSFCH frequency resources, and one or a combination of two or more of the following methods may be used.

[0362] For example, such as Figure 13D As described, the receiving UE can select one PSFCH frequency resource from Δ PSFCH frequency resources using the source ID. More specifically, a PSFCH frequency resource can be selected using a modulo operation of the source ID and Δ. In this case, as referenced... Figure 11 The source ID may include a [Y] bit and may be included in the MAC PDU, wherein the [Y1] bit of the source ID is sent via PSCCH, and the remaining [Y2] bits are sent via PSSCH. The source ID used in the above modulo operation may be either the [Y] bit or the [Y1] bit sent via PSCCH.

[0363] As another example, the receiving UE can randomly select one PSFCH frequency resource from Δ PSFCH frequency resources to be actually transmitted by the receiving UE.

[0364] As another example, the receiving UE can select one PSFCH frequency resource with the lowest (or highest) index from Δ PSFCH frequency resources as the PSFCH frequency resource to be actually transmitted by the receiving UE.

[0365] The above example describes the case where the receiving UE selects one PSFCH frequency resource from Δ PSFCH frequency resources, but this disclosure is not limited thereto. For example, the receiving UE can select two or more PSFCH frequency resources from Δ PSFCH frequency resources. In this case, the example of selecting one PSFCH frequency resource described above can be extended.

[0366] For example, when selecting multiple PSFCH frequency resources based on the source ID, the receiving UE can select one PSFCH frequency resource through the above modulo operation, and then select consecutive PSFCH frequency resources accordingly. In other words, when selecting PSFCH frequency resource index 6 based on the source ID through modulo operation, the receiving UE can select multiple PSFCH frequency resources in ascending order of indices 6, 7, 8, ... Alternatively, the receiving UE can select multiple PSFCH frequency resources in descending order of indices 6, 5, 4, ...

[0367] When randomly selecting multiple PSFCH frequency resources, the receiving UE can randomly select one PSFCH frequency resource and then select consecutive PSFCH frequency resources based on this. In other words, when selecting PSFCH frequency resource index 6 by random selection, the receiving UE can select multiple PSFCH frequency resources in ascending order of indices 6, 7, 8, ... or in descending order of indices 6, 5, 4, ... As another example of randomly selecting multiple PSFCH frequency resources, the receiving UE can randomly select multiple PSFCH frequency resources from Δ PSFCH frequency resources.

[0368] When selecting multiple PSFCH frequency resources using the lowest (or highest) index in reference A, the receiving UE can select multiple PSFCH frequency resources in ascending or descending order of the selected lowest (or highest) index.

[0369] Simultaneously, it may be necessary to determine whether to transmit one PSFCH via one PSFCH frequency resource out of Δ PSFCH frequency resources, or to transmit two or more PSFCH via two or more PSFCH frequency resources. As an example, in the time slots configured for PSFCH resources (i.e., Figure 20A and Figure 20B In slot index 4), it can be associated with the number of HARQ-ACK and / or HARQ-NACK bits to be sent by the receiving UE. More specifically, when the number of HARQ-ACK and / or HARQ-NACK bits to be sent by the receiving UE is 1, one PSFCH can be sent through one PSFCH frequency resource. When the number of HARQ-ACK and / or HARQ-NACK bits to be sent by the receiving UE is 2, two PSFCHs can be sent through two PSFCH frequency resources.

[0370] As another example, the number of PSFCHs to be sent by a receiving UE can be configured in the resource pool information. The receiving UE can select as many PSFCH frequency resources as configured, using the source ID, random selection, or lowest (or highest) frequency index, and send HARQ feedback.

[0371] The above example has primarily described a method for determining the index of a candidate PSFCH frequency resource set including Δ PSFCH frequency resources based on the PSSCH slot index and the starting sub-channel index (or the starting index of the sub-channel). However, this can be extended to a method for determining the index of a candidate PSFCH code resource set including Δ PSCCH code resources based on the PSSCH slot index and the starting sub-channel index (or the starting index of the sub-channel).

[0372] Meanwhile, the above-mentioned PSFCH frequency resource selection method can be referenced. Figure 13D The HARQ operation option 1 described is used for unicast and multicast communication. This is why... Figure 13D As described above, HARQ operation option 2 for multicast communication requires each receiving UE participating in the multicast communication to send HARQ feedback to the sending UE, and therefore can require as many PSFCH frequency and / or code resources as there are receiving UEs. In other words, the sending UE can be required to determine from which receiving UEs have sent HARQ feedback received from different receiving UEs in the group, and one of the following methods can be considered.

[0373] For example, such as Figure 13D As described above, higher layers in multicast communication can provide group information for multicast communication. In this case, such as... Figure 13D As described above, group information may include at least one of the number of group members participating in multicast communication and a group ID. More specifically, when selecting a PSFCH frequency resource based on group information, such as... Figure 13D As illustrated, the receiving UE can select a PSFCH frequency resource using a modulo operation of the group ID and the number of group members, and send HARQ feedback in the corresponding PSFCH frequency resource. When selecting multiple PSFCH frequency resources, the receiving UE can select one PSFCH frequency resource using the above modulo operation, and select consecutive PSFCH frequency resources accordingly. In other words, when selecting PSFCH frequency resource index 6 using a modulo operation of the group ID and the number of group members, the receiving UE can select multiple PSFCH frequency resources in ascending order of indices 6, 7, 8, ... Alternatively, the receiving UE can select multiple PSFCH frequency resources in descending order of indices 6, 5, 4, ... The above example can be extended to the case of selecting one PSFCH code resource or multiple PSFCH code resources.

[0374] Meanwhile, the aforementioned method for selecting PSFCH frequency (or code) resources based on group information, and the method for selecting one or more PSFCHs based on source ID, random selection, or the lowest (or highest) frequency index, can operate as follows: For example, the receiving UE can select a PSFCH frequency resource by modulo operation of the group ID and the number of group members, and select a PSFCH code resource based on the source ID, random selection, or the lowest (or highest) code index. The receiving UE can then transmit the selected PSFCH frequency resource using the code selected by the receiving UE.

[0375] For example, the receiving UE can select a PSFCH frequency resource based on the source ID, random selection, or the lowest (or highest) frequency index, and select a PSFCH code resource by modulo operation of the group ID and the number of group members. The receiving UE can then transmit the selected PSFCH frequency resource using the code selected by the receiving UE.

[0376] In the above example, code resources (or codes) can mean resources distinguished by codes such as scrambling codes or orthogonal overlay codes and different sequences (and cyclic shifts applied to the sequences), as described with reference to Figure 9.

[0377] Figure 21A This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment. Figure 21B This is a diagram illustrating another example of frequency resource allocation for the SL feedback channel according to an embodiment.

[0378] like Figure 9A , Figures 9B to 13D As described above, multicast communication can have two options (Option 1 and Option 2) depending on the SL HARQ operation. Meanwhile, as... Figure 4 As described, unicast, multicast, and broadcast communications can be performed within a resource pool. For example, in resource pool A, UE1 and UE2 can perform unicast, multicast, and broadcast communications. Figure 4 Following the PC-5 RRC connection establishment procedure illustrated, unicast communication is performed. Within the same resource pool A, UE 3 can perform multicast communication with other UEs, and UE 4 can perform broadcast communication with other UEs. As another example, a UE can perform two or more of unicast, multicast, and broadcast communication with the same or different UEs in resource pool A.

[0379] In the various scenarios described above, depending on the PSFCH transmission method used by the receiving UE to transmit the PSFCH, different types of interference may occur to the transmitting UE used to receive the PSFCH. More specifically, as in the reference... Figure 9A and Figures 9B to 13DIn the case of multicast HARQ option 1, receiving UEs in the same group that transmit PSFCH can transmit NACK by using the same time / frequency or the same time / frequency / code resources. In other words, each receiving UE in the same group can transmit a sequence that signifies HARQ NACK, and the receiver of the transmitting UE that receives that sequence can receive overlapping sequences from two or more receiving UEs. Accordingly, the received power intensity of the PSFCH received in the corresponding time / frequency resources may increase, which may interfere with the reception of another PSFCH that is simultaneously received at an adjacent frequency. This can be referred to as in-band transmission (IBE), which may lead to a severe degradation of the PSFCH reception performance. As another example, in the case of multicast HARQ option 2, receiving UEs in the same group that transmit PSFCH simultaneously can technically transmit HARQ-ACK or HARQ-NACK by using independent frequency resources. However, if the number of receiving UEs in the group that transmit PSFCH increases, due to factors such as Figure 13D The PSFCH frequency resource shortage problem described above may prevent frequency division multiplexing (FDM) from being performed between different PSFCHs. Therefore, code division multiplexing (CDM) may be required for some PSFCH resources. In this case, as in multicast option 1 above, PSFCH reception performance may be severely degraded due to IBE problems.

[0380] As a method for solving the IBE problem, the following can be used: Figure 21A and Figure 21B The method shown. More specifically, Figure 21A This illustrates the allocation of PSFCH frequency resources within a resource pool configured for unicast, multicast option 1, and multicast option 2 HARQ feedback transmission. Figure 21A different, Figure 21B The PSFCH frequency resource set available for unicast communication and multicast option 1 HARQ feedback transmission is shown to be separate from the PSFCH frequency resource set available for multicast option 2 HARQ feedback transmission.

[0381] For example, in Figure 21AAmong them, the set of PSFCH frequency resources for multicast option 2 HARQ feedback transmission may include n1 frequency blocks (RBs) or n1 PSFCH sub-channels (indexes from 0 to (n1 - 1)). In addition, the set of PSFCH frequency resources for multicast option 1 HARQ feedback transmission may include n2 RBs or n2 PSFCH sub-channels (indexes from n1 to (n1 + n2 - 1)). The set of PSFCH frequency resources for unicast communication HARQ feedback transmission may include n3 RBs or n3 PSFCH sub-channels (indexes from (n1 + n2) to (n1 + n2 + n3 - 1)). Similarly, Figure 21B shows that the set of PSFCH frequency resources for multicast option 1 HARQ feedback transmission may include n1 RBs or n1 PSFCH sub-channels (indexes from 0 to (n1 - 1)), and the set of PSFCH frequency resources for unicast or multicast option 2 HARQ feedback transmission may include n2 RBs or n2 PSFCH sub-channels (indexes from n1 to (n1 + n2 - 1)).

[0382] Figure 21A and Figure 21B shows that the sets of PSFCH frequency resources for unicast, multicast option 1, and multicast option 2 HARQ feedback transmission are continuous on the frequency axis, but this is an example, and the set of PSFCH frequency resources for HARQ feedback transmission may be discontinuous on the frequency axis.

[0383] Meanwhile, it can be assumed that the PSFCH frequency resources in the resource pool include M RBs as shown in Figure 7 or the resource pool includes M frequency resources as shown in Figure 6 (i.e., when all M RBs are used for PSFCH transmission / reception in the resource pool configured for PSFCH). In this case, Figure 21A shows that n1 + n2 + n3 < M, and Figure 21B shows that n1 + n2 < M. In other words, in Figure 21A , among the M PSFCH frequency resources, (M - (n1 + n2 + n3)) frequency resources may not be used for PSFCH transmission / reception. In addition, in Figure 21B , among the M PSFCH frequency resources, (M - (n1 + n2)) frequency resources may not be used for PSFCH transmission / reception. In such a single resource pool, the unused PSFCH frequency resources can be used for another UE to send SL control information or data information in the corresponding resource pool, or can be used for frequency division multiplexing of different PSFCH formats.

[0384] In other words, in Figure 21A , (n1 + n2 + n3) PSFCH frequency resources can be used as those based on the reference Figure 9A or Figure 9B The PSFCH frequency resources for transmitting / receiving in the described sequence transmission PSFCH format are specified, and the remaining (M - (n1 + n2 + n3)) PSFCH frequency resources can be used for reference-based transmission. Figure 9A or Figure 9B The described channel codec transmits / receives PSFCH frequency resources in another PSFCH format. Similarly, in Figure 21B In this context, (n1+n2) frequency resources can be used for reference-based applications. Figure 9A or Figure 9B The PSFCH frequency resources for transmitting / receiving in the described sequence transmission PSFCH format are specified, and the remaining (M - (n1 + n2)) PSFCH frequency resources can be used for reference-based transmission. Figure 9A or Figure 9B The described channel codec transmits / receives PSFCH frequency resources in another PSFCH format. n1+n2+n3=M, and... Figure 21B In this case, n1 + n2 = M. This could mean that all M PSFCH frequency resources are allocated (i.e., within a PSFCH symbol, PSFCH frequency resources may not be frequency-divided with SL control and data information), or that the same PSFCH format is used across the M PSFCH frequency resources.

[0385] In addition, Figure 21A and Figure 21B In this context, n1, n2, and n3 can represent the same value or different values. Furthermore, as... Figure 21A The mapping shown for the order of PSFCH frequency resources used for multicast option 2, multicast option 1, and unicast communication HARQ feedback is an example, and this disclosure is not limited thereto. Similarly, as Figure 21B The mapping shown is an example of the order in which PSFCH frequency resources are used for multicast option 1, multicast option 2, and unicast communication HARQ feedback, and this disclosure is not limited thereto.

[0386] like Figure 10 , Figure 11 , Figure 13B , Figure 13C , Figure 13D , Figure 14 , Figure 15 , Figure 16 , Figure 17 , Figure 18 , Figure 19 , Figure 20A and Figure 20BAs described in the example, the starting point of the PSFCH frequency resource to be transmitted by each receiving UE (i.e., the starting RB index of the PSFCH or the starting sub-channel index of the PSFCH) can be associated with the starting RB index (or starting sub-channel index) of the PSCCH or PSSCH transmitted by each transmitting UE and / or the slot index of the PSCCH or PSSCH transmitted by each transmitting UE. Therefore, in Figure 21A and Figure 21B In the example, for unicast, multicast option 1 and multicast option 2 HARQ feedback transmission, information about the start and end points of the frequency resource set used by the PSFCH (or the start point of the PSFCH frequency resource set) may be required.

[0387] For example, the PSFCH transmission frequency resource used for unicast HARQ feedback transmission can be determined by the starting subchannel index (or starting RB index) or the time slot index of the PSCCH or PSSCH received by the receiving UE, as shown in the reference. Figure 13A and Figure 13C As described above. In this case, it may be necessary to configure an offset value so that the UE that has received unicast can... Figure 21A The PSFCH frequency resource set shown is used for unicast communication (i.e., PSFCH is transmitted from index (n1+n2) to index (n1+n2+n3-1)). In other words, Figure 13B and Figure 13C This illustrates a UE that has already received a PSCCH or PSSCH in slot index "0" and starting subchannel index (or starting RB index "0") sending a PSFCH with index 0. If... Figure 13B The mapping principle is applied to Figure 21A Then, a UE that has already received a PSCCH or PSSCH via unicast communication in slot index "0" and starting sub-channel index (or starting RB index) "0" can send a PSFCH with index (n1+n2) (i.e., the offset of n1+n2). A UE that has already received a PSCCH or PSSCH via unicast communication in slot index "0" and starting sub-channel index (or starting RB index) "1" can send a PSFCH with index (n1+n2+1). Similarly, if... Figure 13C The mapping principle is applied to Figure 21A Then, a UE that has already received a PSCCH or PSSCH via unicast communication in slot index "0" and starting subchannel index (or starting RB index) "0" can send a PSFCH with index n1+n2 (i.e., an offset of n1+n2). This can be used with applications Figure 13B The same applies to the mapping principle described above. However, if applied... Figure 13CThe mapping is such that a UE that has received a PSCCH or PSSCH via unicast communication in slot index "1" and starting subchannel index (or starting RB index) "0" can send a PSFCH with index (n1+n2+1).

[0388] in addition, Figure 13B and Figure 13C The mapping principle can be applied as follows: Figure 21B If we take Figure 13B The mapping principle is applied to Figure 21B Then, a UE that has received a PSCCH or PSSCH via unicast communication in slot index "0" and starting sub-channel index (or starting RB index) "0" can send a PSFCH with index n1 (i.e., an offset of n1). Furthermore, a UE that has already received a PSCCH or PSSCH via unicast communication in slot index "0" and starting sub-channel index (or starting RB index) "1" can send a PSFCH with index (n1+1). Similarly, if... Figure 13C The mapping principle is applied to Figure 21B Then, a UE that has already received a PSCCH or PSSCH via unicast communication in slot index "0" and starting subchannel index (or starting RB index) "0" can send a PSFCH with index n1 (i.e., offset of n1). This can be used with applications Figure 13B The same applies to the mapping principle described above. However, if applied... Figure 13C The mapping is such that a UE that has received a PSCCH or PSSCH via unicast communication in slot index "1" and starting subchannel index (or starting RB index) "0" can send a PSFCH with index (n1+1).

[0389] The aforementioned offset values ​​can be included in the SL resource pool configuration information.

[0390] The configuration of the PSFCH transmission frequency resources for multicast communication HARQ feedback transmission option 1 can be the same as the configuration of the PSFCH transmission frequency resources for unicast communication HARQ feedback transmission described above. In other words, the configuration of the PSFCH transmission frequency resources for multicast communication HARQ feedback transmission option 1 can be determined by the slot indices of the PSCCH or PSSCH received by two or more receiving UEs and the starting sub-channel index (or starting RB index) of the PSCCH or PSSCH. More specifically, if... Figure 13B The mapping principle is applied to Figure 21AThen, a UE that has already received a PSCCH or PSSCH via multicast communication option 1 in slot index "0" and starting sub-channel index (or starting RB index) "0" can send a PSFCH with index n1 (i.e., an offset of n1). A UE that has already received a PSCCH or PSSCH via multicast communication option 1 in slot index "0" and starting sub-channel index (or starting RB index) "1" can send a PSFCH with index (n1+1). Similarly, if... Figure 13C The mapping principle is applied to Figure 21A Then, a UE that has already received a PSCCH or PSSCH via multicast communication option 1 in slot index "0" and starting subchannel index (or starting RB index) "0" can send a PSFCH with index n1 (i.e., offset of n1). This can be used with applications Figure 13B The same applies to the mapping principle described above. However, if applied... Figure 13C The mapping is such that a UE that has received a PSCCH or PSSCH via multicast communication option 1 in slot index "1" and starting subchannel index (or starting RB index) "0" can send a PSFCH with index (n1+1).

[0391] in addition, Figure 13B and Figure 13C The mapping principle can be applied as follows: Figure 21B If we take Figure 13B The mapping principle is applied to Figure 21B A UE that has already received a PSCCH or PSSCH via multicast communication option 1 in slot index "0" and starting sub-channel index (or starting RB index) "0" can send a PSFCH with index 0 (i.e., offset from 0). A UE that has already received a PSCCH or PSSCH via multicast communication option 1 in slot index "0" and starting sub-channel index (or starting RB index) "1" can send a PSFCH with index 1. Similarly, if... Figure 13C The mapping principle is applied to Figure 21B Then, a UE that has already received a PSCCH or PSSCH via multicast communication option 1 in slot index "0" and starting subchannel index (or starting RB index) "0" can send a PSFCH with index 0 (i.e., offset from 0). This can be used with applications Figure 13B The same applies to the mapping principle described above. However, if applied... Figure 13C If the mapping is such that a UE that has already received a PSCCH or PSSCH via multicast communication option 1 in slot index "1" and starting subchannel index (or starting RB index) "0" can send a PSFCH with index 1.

[0392] Meanwhile, the configuration of the PSFCH transmission frequency resources for multicast communication HARQ feedback transmission option 2 can differ from the configuration of the PSFCH transmission frequency resources for unicast communication HARQ feedback transmission or multicast communication HARQ feedback transmission option 1. This is why, in multicast communication HARQ feedback transmission option 2, receiving UEs in a group that have received PSCCH and PSSCH from the transmitting UE need to independently transmit PSFCH to the transmitting UE using different time / frequency / code resources. Therefore, the amount of PSFCH resources needs to increase proportionally to the number of receiving UEs (i.e., PSFCH transmitting UEs) in the group. For this purpose, a method may be needed for transmitting different PSFCH time / frequency / code resources between different receiving UEs in a group performing multicast communication. As a method, one approach could be to use... Figure 13A and Figure 13D One of the methods described in [the document].

[0393] For example, in Figure 21A In this context, a UE that has already received a PSCCH or PSSCH via multicast communication option 2 at slot index "0" and starting subchannel index (or starting RB index) "0" can start sending a PSFCH from index 0 (i.e., starting the PSFCH from an offset of 0). In this case, it can be assumed that the number of receiving UEs in the group performing multicast communication is G0. (See reference...) Figure 13D As described, each receiving UE can receive from the higher layer the number of group members participating in multicast communication (G0 receiving UEs + one transmitting UE = G0 + 1) and its own group ID. Therefore, each receiving UE can identify the number of independent PSFCH frequency resources required in the PSFCH frequency resource set starting from index 0. Each receiving UE can access these resources through its group ID (e.g., ...). Figure 13D The modulo operation described in [the document] identifies PSFCH resources that can be used by the receiving UE from the PSFCH starting at index 0. If... Figure 13B The mapping principle is applied to Figure 21A If a UE has already received a PSCCH or PSSCH via multicast communication option 2 in slot index "0" and starting subchannel index (or starting RB index) "1", it can start sending PSFCH from PSFCH index 1. Each receiving UE can receive the number of group members participating in multicast communication (G1 receiving UEs + one sending UE = G1 + 1) and its own group ID from the higher layer. Therefore, each receiving UE can identify that G1 independent PSFCH frequency resources are needed in the PSFCH frequency resource set starting from index 1. Each receiving UE can use its group ID (e.g., ...) Figure 13D , Figure 20A and Figure 20BThe modulo operation described in the text identifies PSFCH resources that can be used by the receiving UE from the PSFCH starting at index 0.

[0394] Additionally, if Figure 13C The mapping principle is applied to Figure 21A If a UE has already received a PSCCH or PSSCH via multicast communication option 2 in slot index "1" and starting subchannel index (or starting RB index) "0", it can start transmitting PSFCH from PSFCH index 1. Each receiving UE can receive the number of group members participating in multicast communication (G1 receiving UEs + one transmitting UE = G1 + 1) and its own group ID from the higher layer. Therefore, each receiving UE can identify that G1 independent PSFCH frequency resources are needed in the PSFCH frequency resource set starting from index 1. Each receiving UE can use its group ID (e.g., Figure 13D , Figure 20A and Figure 20B The modulo operation described in the text identifies PSFCH resources that can be used by the receiving UE from the PSFCH starting at index 0.

[0395] Similarly, in Figure 21B In this context, a UE that has already received a PSCCH or PSSCH via multicast communication option 2 at slot index "0" and starting subchannel index (or starting RB index) "0" can start sending a PSFCH from index n1 (i.e., starting the PSFCH from an offset of n1). In this case, it can be assumed that the number of receiving UEs in the group performing multicast communication is G0. (See reference...) Figure 13D As described, each receiving UE can receive from the higher layer the number of group members participating in multicast communication (G0 receiving UEs + one transmitting UE = G0 + 1) and its own group ID. Therefore, each receiving UE can identify the number of independent PSFCH frequency resources required in the PSFCH frequency resource set starting from index n1. Each receiving UE can access these resources through its group ID (e.g., ...). Figure 13D , Figure 20A and Figure 20B The modulo operation described in [the document] identifies PSFCH resources that can be used by the receiving UE from the PSFCH starting at index n1. If... Figure 13B The mapping principle is applied to Figure 21BIf a UE has already received a PSCCH or PSSCH via multicast communication option 2 in slot index "0" and starting subchannel index (or starting RB index) "1", it can start transmitting PSFCH from PSFCH index n1+1. Each receiving UE can receive the number of group members participating in multicast communication (G1 receiving UEs + one transmitting UE = G1+1) and its own group ID from the higher layer. Therefore, each receiving UE can identify that G1 independent PSFCH frequency resources are needed in the PSFCH frequency resource set starting from index n1+1. Each receiving UE can use its group ID (e.g., ...) Figure 13D , Figure 20A and Figure 20B The modulo operation described in [the document] identifies PSFCH resources that can be used by the receiving UE from the PSFCH starting at index 0. Meanwhile, if [the following is done]... Figure 13C The mapping principle is applied to Figure 21A If a UE has already received a PSCCH or PSSCH via multicast communication option 2 in slot index "1" and starting subchannel index (or starting RB index) "0", it can start transmitting PSFCH from PSFCH index n1+1. Each receiving UE can receive the number of group members participating in multicast communication (G1 receiving UEs + one transmitting UE = G1+1) and its own group ID from the higher layer. Therefore, each receiving UE can identify that it needs G1 independent PSFCH frequency resources in the PSFCH frequency resource set starting from index n1+1. Each receiving UE can use its group ID (e.g., ...) Figure 13D , Figure 20A and Figure 20B The modulo operation described in the text identifies PSFCH resources that can be used by the receiving UE from the PSFCH starting at index n1+1.

[0396] Meanwhile, the above-described method for determining the starting index of the PSFCH for unicast, multicast HARQ option 1, and multicast HARQ option 2 operations has been primarily illustrated, relating it to the timeslot index of the received PSSCH and / or the sub-channel index (or RB index) of the received PSSCH (or relating it to the timeslot index of the received PSCCH and / or the sub-channel index (or RB index) of the received PSCCH). However, in addition to this, as Figure 13D As mentioned above, source ID and destination ID can be used. For example, the source ID can be used to find... Figure 21A and Figure 21B The starting point of the PSFCH frequency resource set shown can be determined by the correlation between PSFCH and PSSCH in each PSFCH frequency resource set, and the index of the PSFCH frequency resource used by each receiving UE for PSFCH transmission in the corresponding PSFCH frequency resource set can be determined by the correlation between PSFCH and PSSCH in each PSFCH frequency resource set.

[0397] Figure 21A and Figure 21B The above embodiments can be compared with Figure 20A and Figure 20B The embodiments are used simultaneously. For example, in Figure 20A and Figure 20B The document already describes the association between the PSSCH slot index and the sub-channel start index (or the start sub-channel index) and the PSFCH frequency and / or code resource start index, or the association between the PSSCH slot index and the sub-channel start index (or the start sub-channel index) and the PSFCH candidate frequency and / or code resource set start index. In this case, when defining the above correlation between PSSCH resources and PSFCH resources, a mapping relationship can be defined such that PSFCH resources (or resources of the candidate PSFCH set) are mapped to the excluded... Figure 21A and Figure 21B The remaining portion after the unused resources are shown.

[0398] Figure 22A This is a flowchart illustrating the operation of a receiving UE for SL HARQ feedback transmission according to an embodiment. Figure 22B This is a flowchart illustrating the operation of a receiving UE for SL HARQ feedback transmission according to an embodiment.

[0399] like Figure 21A and Figure 21B As described, UEs can coexist in the same resource pool, and UEs can use unicast, multicast (including options 1 and 2), and broadcast communication. In this case, HARQ feedback can be omitted in broadcast communication. Figure 4 As described, HARQ feedback can be activated or deactivated in unicast and multicast communications. In other words, as mentioned above, whether to operate HARQ feedback depends on the broadcast scheme (unicast, multicast, or broadcast), and various HARQ feedback operation methods (Options 1 and 2) can exist in a specific broadcast scheme (multicast). Furthermore, HARQ feedback can be activated / deactivated in some broadcast schemes (unicast or multicast). Therefore, when unicast, multicast, and broadcast communications share the same resource pool (i.e., when UEs used to perform unicast, multicast, and broadcast coexist in one resource pool), it may be necessary to design a signaling scheme to support the activation / deactivation of HARQ feedback and the aforementioned HARQ feedback operation methods. For this purpose, at least one of the following can be considered.

[0400] 1) Whether to activate / deactivate SL HARQ operations can be explicitly or implicitly included in the resource pool information configured by the base station through RRC information or system information. In out-of-coverage environments where no base station is present, whether to activate / deactivate SL HARQ operations can be explicitly or implicitly included in the pre-configured resource pool information. Explicitly configuring or pre-configuring whether to activate / deactivate SL HARQ operations can mean one of the following: explicitly including whether to activate / deactivate SL HARQ operations in the resource pool information configuration information via a bit, explicitly including it via "Enable / Disable", or explicitly including it via "On / Off". Conversely, implicitly configuring or pre-configuring whether to activate / deactivate SL HARQ operations can mean that if the resource pool configuration information includes parameters regarding SL HARQ operations, the SL HARQ operation is activated, and unless the resource pool configuration information includes parameters regarding HARQ operations, the SL HARQ operation is deactivated. Therefore, V2X sending and receiving UEs that have received resource pool configuration information can determine whether to activate / deactivate the SL HARQ operation in the corresponding resource pool.

[0401] At the same time, such as Figure 2 As described above, broadcast communication can mean that a V2X transmitting UE broadcasts SL control and data information to multiple unspecified UEs present around it. Therefore, since the V2X transmitting UE and the V2X receiving UE performing the broadcast communication are unaware of each other's existence, they may be unable to operate SL HARQ feedback. In this case, if the V2X UE performing the broadcast communication shares a resource pool with the V2X UE performing unicast or multicast communication, the understanding of whether to operate SL HARQ operation may differ between the transmitting UE and the receiving UE if 1) above is used.

[0402] For example, although the transmitting UE sends SL data via broadcast communication, the receiving UE may send HARQ feedback to the transmitting UE based on the HARQ operation activation configuration information included in the resource pool configuration information. Because the transmitting UE has already used broadcast communication, it does not expect feedback from the receiving UE and may choose not to receive the HARQ feedback sent by the receiving UE. Due to the different understanding between the transmitting and receiving UEs, the receiving UE may unnecessarily send PSFCH, which could increase power consumption and lead to half-duplex problems. In this case, for UEs that cannot perform SL transmission and reception simultaneously (e.g., UEs where the SL transmission RF chain and SL reception RF chain are not separate), the half-duplex problem may cause the receiving UE to be unable to receive PSFCH from another UE in the corresponding resource pool due to the unnecessary PSFCH transmission as described above.

[0403] The above problems are described in detail below. The broadcast type (unicast, multicast, or broadcast) can be determined by the application layer, and HARQ operations can be performed by the physical layer and MAC layer. Therefore, when the data generated by the application layer of the sending UE is broadcast communication, the physical layer and MAC layer of the sending UE can determine not to perform a HARQ operation. Thus, as in 1), although the HARQ operation activation information is explicitly or implicitly included in the resource pool information received by the sending UE, the sending UE can ignore it. However, before receiving the corresponding broadcast data through the application layer of the receiving UE, the UE that has already received the broadcast data from the sending UE does not know the broadcast type, and therefore the physical layer and MAC layer may not be able to identify whether the corresponding data is broadcast type data. Therefore, the receiving UE using 1) may send HARQ feedback to the sending UE based on the HARQ operation activation information configured in the resource pool.

[0404] Therefore, in order to solve the above problems, the following methods may be needed for the physical layer and MAC layer of the receiving UE to identify whether the HARQ operation is activated.

[0405] 2) such as Figure 22A As shown, the transmitting UE and receiving UE performing unicast communication can obtain the activation information for the SL HARQ operation through the resource pool configuration information. In this case, when the SL HARQ operation activation information is explicitly or implicitly configured in the resource pool information used for SL transmission, the transmitting UE can send a 1-bit indicator in the SCI indicating whether the HARQ operation is activated to the receiving UE. For example, "0" can mean deactivating the SL HARQ operation, and "1" can mean activating the SL HARQ operation. The receiving UE can only send HARQ feedback to the transmitting UE if the activation of the SL HARQ operation is explicitly or implicitly configured in the resource pool information used for SL reception, and the 1-bit indicator in the SCI sent by the transmitting UE also indicates the activation of the SL HARQ operation. Even if the activation of the SL HARQ operation is explicitly or implicitly configured in the resource pool information used for SL reception, if a 1-bit indicator in the SCI sent by the transmitting UE indicates the deactivation of the HARQ operation, then HARQ feedback need not be sent to the transmitting UE.

[0406] In scenario 2) above, it's possible that HARQ operation deactivation can be configured in the resource pool configuration information, while the sending UE indicates HARQ operation activation via a 1-bit indicator in the SCI. This could mean the resource pool lacks PSFCH resources for HARQ operation, and therefore the receiving UE prioritizes the resource pool configuration information and may not send HARQ feedback to the sending UE. In other words, the receiving UE can ignore the HARQ operation activation indicated by the 1-bit indicator in the SCI sent by the sending UE.

[0407] Meanwhile, in multicast communication, the sending UE and the receiving UE may need a common protocol regarding whether to use Option 1 or Option 2. For this purpose, the following can be considered.

[0408] 3) Resource pool configuration information provided by the base station through system and RRC signaling, or pre-configured resource pool configuration information, may include HARQ operation information (Option 1 or Option 2). UEs used to perform transmission and reception in the corresponding resource pool via multicast communication can operate Option 1 or Option 2 based on the HARQ operation information configured in the resource pool.

[0409] However, it may be necessary to consider the method by which the receiving UE identifies whether to use Option 1 or Option 2 in multicast communication. More specifically, whether to use Option 1 or Option 2 can be determined by the application layer (or the V2X layer between the application layer and the AS layer, and hereinafter, the application layer and V2X layer are used interchangeably), and the physical layer and MAC layer of the transmitting UE can receive whether to use Option 1 or Option 2 from its application layer. For example, the application layer can transmit the number of group members involved in the multicast communication and the group ID information that the transmitting UE can use to the physical layer through the MAC layer. If the above information is not received from the application layer, the MAC layer and physical layer of the transmitting UE do not know the information about the group (i.e., the number of group members and the group ID), and therefore may request to operate Option 1. Meanwhile, the MAC layer and physical layer of the transmitting UE that have received the above group-related information can operate Option 2. In this case, although the above information is provided from the application layer, the MAC layer and physical layer of the transmitting UE can operate Option 1 according to conditions. For example, when the number of group members is equal to or greater than a specific value configured (or pre-configured) by the base station via RRC or system information, the MAC and physical layers of the transmitting UE can operate Option 1. Alternatively, when the amount of PSFCH resources is less than the number of group members, the MAC and physical layers of the transmitting UE can operate Option 1.

[0410] Based on the above example, whether to use option 1 or option 2 is determined by the application layer, and therefore the physical and MAC layers of the UE that have received SL data from the sending UE may not know whether to use option 1 or option 2. Therefore, similar to the above discussion of whether to activate or deactivate HARQ operations, 3) may be incorrect. A method to resolve these issues may be needed, and 4) below could be considered.

[0411] 4) such as Figure 22BAs shown, the transmitting UE and receiving UE performing multicast communication can obtain SL HARQ operation activation information through resource pool configuration information. In this case, similar to the operation in unicast communication described above, the transmitting UE can send SL HARQ feedback activation information to the receiving UE via SCI. Furthermore, the transmitting UE can send a 1-bit indicator for SL HARQ operation information to the receiving UE as follows: for example, "0" can mean using option 1, and "1" can mean using option 2. The receiving UE can send HARQ feedback to the transmitting UE via PSFCH using either option 1 or option 2 based on the 1-bit indicator in the SCI sent by the transmitting UE. In other words, according to the above example, when SL HARQ operation is explicitly or implicitly activated in the resource pool configuration information, a 1-bit message indicating whether HARQ operation is activated or deactivated via SCI can be sent, and when HARQ operation is activated via SCI, a 1-bit indicator for HARQ operation information can be further sent to the receiving UE (i.e., two bits can indicate whether HARQ is activated and whether HARQ feedback option 1 or option 2 is used). For example, HARQ activation can be configured explicitly or implicitly in the resource pool configuration information, and the sending UE that wants to perform multicast communication in the corresponding resource pool can indicate the following to the receiving UE using two bits of the SCI indicator. For example, "00" can mean that the receiving UE will not send HARQ feedback. "01" can mean that the receiving UE will send HARQ feedback via multicast option 1, and "10" can mean that the receiving UE will send HARQ feedback via multicast option 2.

[0412] As described above, the physical layer and MAC layer can disregard unicast, multicast, and broadcast communications. Therefore, regardless of the type of unicast, multicast, or broadcast communication, the number of bits constituting the SCI needs to remain the same to reduce the complexity of UE SCI decoding. Thus, a transmitting UE that uses broadcast communication to send SL control information and data information can configure "00" in its SCI to prevent a receiving UE from sending HARQ feedback via PSFCH in a resource pool where HARQ operation is activated. Even without recognizing the broadcast type, the physical layer and MAC layer of a UE that has received the SCI can also refrain from sending PSFCH based on the "00" indicator in the SCI. Similarly, a transmitting UE that uses unicast or multicast communication to send SL control information and data information can configure "00" in its SCI to prevent a receiving UE from sending HARQ feedback via PSFCH in a resource pool where HARQ operation is activated. Even without recognizing the broadcast type, the physical layer and MAC layer of a UE that has received the SCI can also refrain from sending PSFCH based on the "00" indicator in the SCI.

[0413] Meanwhile, in the multicast communication example above, it is assumed that each of the activation and deactivation information of the SL HARQ operation and the SL HARQ operation information (Option 1 or Option 2) is sent to the SCI via a separate 1-bit indicator. In other words, a 2-bit indicator may be needed in the SCI to send two messages. Furthermore, as mentioned above, since the physical and MAC layers at the receiver cannot recognize the broadcast type, it may be necessary to include 2 bits of information in the SCI regardless of the broadcast type to reduce the SCI decoding complexity at the receiver. This may increase the number of bits sent to the SCI, thereby increasing signaling overhead and channel coding / decoding rate, thus degrading SCI coverage. Therefore, a method is needed to address these issues, and at least one of the following methods can be considered.

[0414] 1) Since the deactivation of HARQ operations in the resource pool configuration information means that PSFCH resources are not configured in SL HARQ operations, this may mean that HARQ operations in unicast communication, HARQ option 1 operations in multicast communication, HARQ option 2 operations in multicast communication, and HARQ operations in broadcast communication are all impossible.

[0415] 2) When HARQ operation is activated in the resource pool configuration information, this may mean that PSFCH resources for SLHARQ operation have been configured. Therefore, the sending UE can indicate to the receiving UE whether to operate HARQ via a bit of the SCI. More specifically, although HARQ operation is activated in the resource pool configuration information, the sending UE for unicast, multicast, and broadcast communications can set one bit of the SCI indicator to "0" and send it to the receiving UE to deactivate HARQ operation. Although HARQ operation is activated in the resource pool configuration information, the receiving UE that has received the SCI may not send HARQ feedback to the sending UE. Meanwhile, when SL HARQ operation is activated in the resource pool configuration information and the sending UE wants to operate HARQ in unicast communication or via option 1 or option 2 in multicast communication, the sending UE can set one bit of the SCI indicator to "1" and send it to the receiving UE. As mentioned above, since the physical layer and MAC layer of the receiving UE cannot recognize the broadcast type, if the 1-bit indicator of SCI is set to "1", the physical layer and MAC layer of the receiving UE may not be able to determine whether it means a HARQ feedback operation in unicast or a HARQ feedback operation in multicast.

[0416] This can be determined by the receiving UE through the source ID and / or destination ID included in the SCI. For example, when the source ID and / or destination ID are divided into two sets, and a source ID and / or destination ID corresponding to set 1 is detected, the physical layer and MAC layer of the receiving UE can identify from the corresponding ID that it signifies unicast communication. Conversely, when a source ID and / or destination ID corresponding to set 2 is detected, the physical layer and MAC layer of the receiving UE can identify from the corresponding ID that it signifies multicast communication. Various methods can exist for configuring the aforementioned set 1 and set 2. For example, the sending UE can set the indicator to "1" and send an 8-bit source ID and a 16-bit destination ID to the receiving UE via the SCI. In this case, when an even-numbered source ID and / or destination ID is detected, the physical layer of the receiving UE can determine that it is unicast communication. When an odd-numbered source ID and / or destination ID is detected, the physical layer of the receiving UE can determine that it is multicast communication. As another example, the 8-bit source ID and 16-bit destination ID are converted into decimal numbers, and the physical layer of the receiving UE can determine that it is unicast communication when the source ID and / or destination ID is equal to or greater than a specific threshold (or greater than the threshold).

[0417] Having identified the receiving UE for multicast communication using the methods described above, further identification is needed to determine whether it signifies HARQ option 1 or HARQ option 2 in the multicast communication. This can be performed as follows: For example, when the SCI includes information about the sending UE's location (e.g., including the sending UE's area ID or at least one of latitude and longitude) and range requirements, the receiving UE's physical layer can determine that it will execute multicast HARQ option 1. When the SCI does not include the aforementioned information, the receiving UE's physical layer can determine that it will execute multicast HARQ option 2.

[0418] Figure 23 This is a diagram illustrating a transmit power control method for an SL feedback channel according to an embodiment.

[0419] V2X transmitting UEs can perform SL transmit power control for PSCCH and PSSCH transmission. For SL transmit power control, the V2X transmitting UE can send an SL reference signal to the V2X receiving UE, and the V2X receiving UE, having received the SL reference signal, can measure the SL RSRP and report it to the V2X transmitting UE. In this case, the SL RSRP can be measured by the V2X receiving UE via the SL CSI-RS, or it can be measured by the V2X receiving UE using a reference signal (e.g., DMRS) transmitted via the SL control channel or data channel. The V2X transmitting UE, having received the SL RSRP from the V2X receiving UE, can estimate the path loss value based on the received SL RSRP and its transmit power, and perform SL transmit power control by reflecting this path loss value.

[0420] Similarly, when a V2X receiving UE sends a PSFCH to a V2X sending UE, it may be required to perform SL transmit power control. SL transmit power control for PSFCH can be performed by at least one of the following methods.

[0421] Method 1) The V2X receiving UE can transmit the PSFCH using the configured maximum transmit power. In this case, the configured maximum transmit power can be configured by the V2X receiving UE based on metrics configured from higher layers (e.g., distance information) or by the QoS received by the V2X receiving UE from higher layers.

[0422] Method 2) The V2X receiving UE can configure the PSFCH transmit power value using the DL path loss value with the base station and the SL transmit power control parameters included in the PSFCH resource pool configuration information. In this case, the DL path loss value with the base station can be estimated by the V2X receiving UE through the secondary synchronization signal (SSS) transmitted by the base station via DL, or it can be estimated by the V2X receiving UE through the DMRS and SSS of the physical broadcast channel (PBCH). The signal for which the V2X receiving UE needs to estimate the DL path loss can be included in the resource pool information sent by the base station to the V2X UE via RRC configuration or system information. When the V2X receiving UE is outside the coverage of the base station and therefore cannot use the DL path loss value for PSFCH transmit power control, the V2X receiving UE can configure the PSFCH transmit power value by using only other transmit power control parameters without using the DL path loss value. As another example, when the V2X receiving UE is within the coverage of the base station, Method 2 can be used to configure the PSFCH transmit power, and when the V2X receiving UE is outside the coverage of the base station, Method 1 can be used to configure the PSFCH transmit power.

[0423] Method 3) The V2X transmitting UE can notify the V2X receiving UE of the transmit power value used by the V2X transmitting UE for PSCCH or PSSCH transmission. In this case, the V2X transmitting UE can send information about its transmit power value to the V2X receiving UE via SL control information or MAC CE. The V2X receiving UE can measure SLRSRP using the SL CSI-RS or SL DMRS transmitted by the V2X transmitting UE via PSCCH or PSSCH and the transmit power value received by the V2X transmitting UE for PSCCH or PSSCH transmission, and use it to estimate the SL path loss value. The V2X receiving UE can configure the transmit power value of PSFCH using the SL path loss value estimated by the V2X receiving UE and the SL transmit power parameters included in the PSFCH resource pool configuration information.

[0424] Method 4) A mapping relationship can be configured between the SL RSRP value measured by the V2X receiving UE and the PSFCH transmit power. The mapping relationship is illustrated in Table 2 below, and when the SL RSRP value measured by the V2X receiving UE is -X1 dBm, the V2X receiving UE can use Y1 dBm as the PSFCH transmit power. Table 2 below can be configured by the base station or can be pre-configured. Depending on the power level or QoS of the V2X UE (e.g., minimum communication range), two or more mapping tables as shown in Table 2 below may exist. Table 2 below illustrates a one-to-one mapping relationship between SL RSRP and PSFCH transmit power values, but a one-to-many mapping relationship may exist. In other words, two or more SL RSRP values ​​can be mapped to one PSFCH transmit power value. In Table 2 below, SL RSRP values ​​can have a difference of Z1 dB (i.e., the step size, granularity, or resolution of the SL RSRP values ​​is Z1 dB). Similarly, PSFCH transmit power values ​​can have a difference of Z2 dB (i.e., the step size, granularity, or resolution of the PSFCH transmit power values ​​is Z2 dB). In this case, Z1 and Z2 can be the same or different. Table 2 below shows the mapping between SL RSRP and PSFCH transmit power.

[0425] [Table 2]

[0426]

[0427] Figure 23 An example of a PSFCH transmit power control method based on the above example is shown. More specifically, the V2X receiving UE can obtain information about pre-configured PSFCH parameters from the base station or the V2X transmitting UE. In this case, the information about the PSFCH parameters may include... Figure 4At least one of the PSFCH-related information described in the document. Furthermore, the information regarding the PSFCH parameters may include information about the PSFCH transmit power, as well as the aforementioned information. If the V2X receiving UE has received the SL RSRP from the V2X transmitting UE (i.e., if the V2X receiving UE possesses the SL RSRP information measured by the V2X transmitting UE), the V2X receiving UE can estimate the SL path loss. The V2X receiving UE can configure the PSFCH transmit power using at least one of the obtained information about the PSFCH parameters and the estimated path loss value. The V2X receiving UE can transmit the PSFCH to the V2X transmitting UE using the PSFCH transmit power value configured by the V2X receiving UE.

[0428] If the V2X receiving UE has not yet received the SL RSRP from the V2X transmitting UE (i.e., if the V2X receiving UE does not have the SL RSRP information measured by the V2X transmitting UE), the V2X receiving UE can determine whether the mapping table between the SL RSRP value and the PSFCH transmit power value is configured as illustrated in Table 2. A V2X receiving UE configured with the table shown in Table 2 can select a PSFCH transmit power value mapped to the SL RSRP value measured by the V2X receiving UE, configure the PSFCH transmit power value, and send the PSFCH to the V2X transmitting UE (Method 4).

[0429] If the V2X receiving UE is not configured with a table such as Table 2, the V2X receiving UE can configure the PSFCH transmit power value through methods 1 and 2 above and send the PSFCH to the V2X transmitting UE.

[0430] As Figure 23 Another example is that if SL RSRP information does not exist, the V2X receiving UE that has determined whether SL RSRP information exists can configure the PSFCH transmit power value through methods 1 and 2 above without determining whether a table such as Table 2 is configured, and send the PSFCH to the V2X transmitting UE.

[0431] As Figure 23 In another example, the V2X receiving UE can immediately determine whether a table as shown in Table 2 is configured, without needing to determine the existence of SL RSRP information. When a table as shown in Table 2 is configured, the V2X receiving UE can choose to map a PSFCH transmit power value to the SL RSRP value measured by the V2X receiving UE, configure the PSFCH transmit power value, and send the PSFCH to the V2X transmitting UE (Method 4). If the V2X receiving UE fails to configure a table such as Table 2, the V2X receiving UE can configure the PSFCH transmit power value using Methods 1 and 2 described above and send the PSFCH to the V2X transmitting UE.

[0432] Figure 24 This is a block diagram illustrating the internal structure of the transmitting UE according to an embodiment.

[0433] refer to Figure 24 The transmitting UE 2400 disclosed herein may include a transceiver 2410, a controller 2420, and a memory 2430. The memory 2430 may also be referred to as a storage unit 2430. However, the components of the transmitting UE 2400 are not limited thereto. For example, the transmitting UE 2400 may include more or fewer components than those described above. Furthermore, the transceiver 2410, controller 2420, and memory 2430 may be implemented as a single chip.

[0434] Transceiver 2410 can transmit signals to or receive signals from a base station or another UE. These signals may include synchronization signals, reference signals, control information, and data. For this purpose, transceiver 2410 may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, an RF receiver for low-noise amplification of the received signal and down-converting the received signal, etc. Furthermore, transceiver 2410 can receive signals via a radio channel, output signals to controller 2420, and transmit signals output from controller 2420 via a radio channel.

[0435] The memory 2430 can store programs and data required for operating the transmitting UE 2400. Additionally, the memory 2430 can store control information or data included in signals transmitted or received by the transmitting UE 2400. The memory 2430 may include storage media such as ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media. Furthermore, the memory 2430 may include multiple memories.

[0436] Controller 2420 can control a series of operations to allow UE 2400 to operate as described above. Controller 2420 may include at least one processor. Controller 2420 may include multiple processors and execute programs stored in memory 2430 to control the feedback channel resource allocation method described herein and the transmission and reception of the SL feedback channel transmitted between UEs.

[0437] Figure 25 This is a block diagram illustrating the internal structure of the receiving UE according to an embodiment.

[0438] refer to Figure 25The receiving UE 2500 of this disclosure may include a transceiver 2510, a controller 2520, and a memory 2530. However, the components of the receiving UE 2500 are not limited thereto. For example, the receiving UE 2520 may include more or fewer components than those described above. In addition, the transceiver 2510, the controller 2520, and the memory 2530 may be implemented as a single chip.

[0439] Transceiver 2510 can transmit signals to or receive signals from a base station or another UE. These signals may include synchronization signals, reference signals, control information, and data. For this purpose, transceiver 2510 may include an RF transmitter for up-converting the frequency and amplifying the transmitted signal, an RF receiver for low-noise amplification of the received signal and down-converting the received signal, etc. Furthermore, transceiver 2510 can receive signals via a radio channel, output signals to controller 2520, and transmit signals output from controller 2520 via a radio channel.

[0440] The memory 2530 can store programs and data required for the operation of the transmitting UE 2500. Additionally, the memory 2530 can store control information or data included in signals transmitted or received by the receiving UE 2500. The memory 2530 may include storage media such as ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media. Furthermore, the storage device 2530 may include multiple memories.

[0441] Controller 2520 can control a series of operations to allow receiving UE 2500 to operate as described above. Controller 2520 may include at least one processor. Controller 2520 may include multiple processors and execute programs stored in memory 2530 to control the feedback channel resource allocation method and the transmission and reception of the SL feedback channel between UEs.

[0442] Figure 26 This is a block diagram illustrating the internal structure of a base station according to an embodiment.

[0443] refer to Figure 26 The base station 2600 disclosed herein may include a transceiver 2610, a controller 2620, and a memory 2630. However, the components of the base station 2600 are not limited thereto. For example, the base station 2600 may include more or fewer components than those described above. Furthermore, the transceiver 2610, controller 2620, and memory 2630 may be implemented as a single chip.

[0444] Transceiver 2610 can transmit signals to or receive signals from a base station or another UE. These signals may include synchronization signals, reference signals, control information, and data. For this purpose, transceiver 2610 may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, an RF receiver for low-noise amplification of the received signal and down-converting the frequency of the received signal, etc. Furthermore, transceiver 2610 can receive signals via a radio channel, output signals to controller 2620, and transmit signals output from controller 2620 via a radio channel.

[0445] The memory 2630 can store programs and data required to operate the base station 2600. Additionally, the memory 2630 can store control information or data included in signals transmitted or received by the base station 2600. The memory 2630 may include storage media such as ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media. Furthermore, the storage device 2630 may include multiple memories.

[0446] Controller 2620 can control a series of processes for enabling the UE to operate as described above. Controller 2620 may include at least one processor. Controller 2620 may include multiple processors and execute programs stored in memory 2630 to control the feedback channel resource allocation method and the transmission and reception of the SL feedback channel between UEs.

[0447] Figure 27 This is a diagram illustrating a V2X communication method according to an embodiment.

[0448] Figure 27 This illustrates a scenario where the UE performs SL communication using one or more carriers (or BWPs). When the UE needs to receive PSSCH and send PSFCH including HARQ-ACK information for the corresponding PSSCH across multiple carriers, refer to... Figure 27 One or a combination of the methods shown are possible. In the following description, a carrier can be replaced and applied by a BWP. When a carrier is replaced by a BWP, it is possible for the UE to transmit or receive multiple BWPs on a single carrier via an SL. Furthermore, it is possible for multiple carriers or multiple BWPs to be present for each carrier, and this disclosure is not limited thereto.

[0449] Case 1 involves executing both PSSCH and PSFCH on the same carrier. That is, when a PSSCH is received on carrier 1, a PSFCH including HARQ-ACK information is executed on carrier 1. When a PSSCH is received on carrier 2, a PSFCH including HARQ-ACK information is executed on carrier 2. When a PSSCH is received on carrier 3, a PSFCH including HARQ-ACK information is executed on carrier 3. When a PSSCH is received on carrier 4, a PSFCH including HARQ-ACK information is executed on carrier 4. Therefore, when... Figure 27 When configuring four carriers and receiving PSSCHs simultaneously on each carrier, it's possible for the UE to simultaneously transmit the corresponding PSFCHs within a specific time slot. Depending on the UE's capabilities, it can transmit all scheduled PSFCHs or only some. When transmitting some PSFCHs, the UE can select which PSFCHs to transmit using a method that prioritizes them by carrier index or based on PSFCH priority information. Transmitting only some PSFCHs is possible when the UE's capabilities are determined for each carrier or when the UE determines the maximum number of PSFCHs to transmit. Alternatively, when the sum of the transmission powers of the scheduled PSFCHs exceeds the UE's maximum transmission power, it's possible for the UE to transmit only some of the scheduled PSFCHs because it cannot transmit all of them.

[0450] Case 2 illustrates scenarios where the carrier transmitting or receiving the PSSCH is the same as or different from the carrier transmitting or receiving the PSFCH including HARQ-ACK information of the PSSCH. For example, it illustrates a case where HARQ-ACK information of the PSSCH transmitted or received on carrier 1 is transmitted or received on carrier 2. It illustrates a case where HARQ-ACK information of the PSSCH transmitted or received on carrier 3 is transmitted or received on carrier 4. Therefore, the PSFCH transmitted or received on a specific carrier may include HARQ-ACK information of the PSSCH transmitted or received on multiple carriers. When a UE sends HARQ-ACK information for multiple PSSCHs to the PSFCH, the UEs that have already sent the corresponding PSSCHs can be different from each other, and therefore can send the PSFCHs separately through independent physical channel resources without reusing the HARQ-ACK information. In this case, the PSFCH includes 1 bit of HARQ-ACK information. When the UEs that have already sent the corresponding PSSCHs are the same, the UE can reuse the HARQ-ACK information and send it through a single PSFCH. In this case, the PSFCH can include HARQ-ACK information with two or more bits. In case 2, the carrier for transmitting or receiving the PSSCH and the carrier of the PSFCH including the HARQ-ACK information of the PSSCH are predetermined by the higher-layer signaling. Therefore, the transmission or reception of the PSFCH for transmitting or receiving the PSSCH in the specific carrier i can be performed in the specific carrier i or j predetermined by the higher-layer signaling information.

[0451] In scenario 3, the carrier for transmitting or receiving the PSSCH and the carrier for transmitting or receiving the PSFCH including HARQ-ACK information of the PSSCH can be the same or different from each other. For example, for a PSSCH transmitted or received in carrier index 1, the UE can transmit or receive the PSFCH in carrier index 1 or 2. For a PSSCH transmitted or received in carrier index 2, the UE can transmit or receive the PSFCH in carrier index 1 or 3. For a PSSCH transmitted or received in carrier index 3, the UE can transmit or receive the PSFCH in carrier index 4. For a PSSCH transmitted or received in carrier index 4, the UE can transmit or receive the PSFCH in carrier index 3 or 4. For this purpose, the carrier index for transmitting or receiving the PSFCH can be dynamically identified using the SCI (or DCI) used to schedule the PSSCH. Therefore, the PSFCH including HARQ-ACK information of the PSSCH transmitted or received in specific carrier i can be transmitted or received in specific carrier i, determined by the SCI. In summary, the operations of Case 2 and Case 3 are similar to each other, but Case 2 and Case 3 are different and are distinguished from each other based on whether the signaling used to determine the carrier of the PSFCH to be transmitted or received is a higher-layer signal (Case 2) or an L1 signal (Case 3).

[0452] The PSCCH used for scheduling PSSCH can also be transmitted or received on the same carrier or different carriers, and it is possible to perform this through at least one or a combination of cases 1 to 3. For each UE, a set of different PSSCH carriers can be possible. For each UE, a set of different PSFCH carriers can be possible. For each UE, a set of different PSCCH carriers can be possible. The aforementioned carriers can be replaced and used by information configured by time, frequency, or code resources, bandwidth portions, or cell.

[0453] When a UE supports multiple carriers, the set of carriers used for SL transmission and the set of carriers used for SL reception can be the same or different from each other. As an example of cases where the sets differ, it's possible for a UE to perform SL reception via multiple carriers but SL transmission via only one carrier. The PSFCH can be configured for all carriers or only some carriers based on higher-layer signal configuration, and the PSFCH offset and transmit / receive period configured for each carrier can be the same or different from each other. The PSFCH-related higher-layer signal configuration can be determined specifically for the UE, the carrier, or the carrier group.

[0454] Figure 28 This is a diagram illustrating a method by which a UE allocates transmit power for multiple PSFCH transmissions according to an embodiment.

[0455] The following section describes the method for allocating PSFCH transmit power to the UE. This involves scheduling N for the UE. sch,Tx In the case of multiple PSFCHs, when the UE reports that it can send a maximum of N PSFCHs from the resource pool in which it sends PSFCHs. max When there are a number of PSFCHs, the UE determines the number N of PSFCHs that can be sent simultaneously. Tx and the power P used for transmission of the k-th PSFCH PSFCH,k (i). K has 1 and N Tx The values ​​between and , where i means the PSFCH transmission position in the active BWP b of carrier f. The UE can determine whether dl-P0-PSFCH can be configured, and N max Comparison with P CMAX The PSFCH transmission power is determined by comparison. For example, the determination of the PSFCH transmission power can be made in a scheme as shown in pseudocode 1.

[0456] [Starting with pseudocode 1]

[0457] 1) If dl-P0-PSFCH is provided to the UE,

[0458] P PSFCH,one = P O,PSFCH + 10·log 10 (2 u ) + α PSFCH ·PL [dBm]

[0459] - P O,PSFCH It is dl-P0-PSFCH.

[0460] - If dl-Alpha-PSFCH is provided, then αPSFCH is the corresponding value; otherwise, it is 1.

[0461] -PL is the path loss value and the value estimated from the reference signal.

[0462] 2) If N sch,Tx ≤ N max ,

[0463] 3) P PSFCH,one + 10·log 10 (N sch,Tx ) ≤ P CMAX ,

[0464] - N Tx = N sch,Tx And P PSFCH,k (i) = P PSFCH,one [dBm]

[0465] 3) If PPSFCH,one + 10·log 10 (N sch,Tx ) > P CMAX ,

[0466] -UE determines N based on the following conditions Tx Quantity: PSFCH.

[0467] - N Tx ≥ max(1,Σ K i =1M i M i K is the number of PSFCHs with priority value i, and K is the number of PSFCHs allocated simultaneously with priority values ​​1, 2, ... while satisfying P. PSFCH,one + 10·log 10 (max(1,Σ K i =1M i )) ≤ P CMAX The maximum value.

[0468] Otherwise, 0

[0469] - P PSFCH,k (i) = min(P CMAX - 10·log 10 (N Tx,PSFCH ), P PSFCH,one [dBm]

[0470] 2) If N sch,Tx > N max ,

[0471] -UE automatically selects N according to the ascending order of the corresponding field values. max Send one PSFCH.

[0472] 3) If P PSFCH,one + 10·log 10 (N max ) ≤ P CMAX ,

[0473] - N Tx = N max And P PSFCH,k (i) = P PSFCH,one [dBm]

[0474] 3) If P PSFCH,one + 10·log 10 (N max ) > P CMAX ,

[0475] -UE considers the following conditions to determine N Tx Number of PSFCHs sent.

[0476] - N Tx ≥ max(1,Σ K i =1M i M i K is the number of PSFCHs with priority value i, and K is the number of PSFCHs allocated simultaneously with priority values ​​1, 2, ... while satisfying P. PSFCH,one + 10·log 10 (max(1,Σ K i =1M i )) ≤ P CMAX The maximum value.

[0477] Otherwise, 0

[0478] - P PSFCH,k (i) = min(P CMAX - 10·log 10 (N Tx,PSFCH ), P PSFCH,one [dBm]

[0479] 1) If no dl-P0-PSFCH is provided to the UE,

[0480] - P PSFCH,k (i) = P CMAX - 10·log 10 (N Tx,PSFCH [dBm]

[0481] - The UE determines N autonomously according to the ascending order of the corresponding priority field values. Tx,PSFCH Send one PSFCH.

[0482] [End of Pseudocode 1]

[0483] For example, refer to the description in pseudocode 1 above. Figure 28 When dl-P0-PSFCH is provided to the UE, if five PSFCHs (N) are scheduled... sch,Tx =5) and N max If the value is 4, then one PSFCH needs to be excluded based on priority. If in Figure 28 If PSFCH transmission 5 has the lowest priority, then PSFCH transmission 5 will not be executed. Afterwards, the UE will reference the dl-P0-PSFCH configuration value used for transmitting the four PSFCHs and adjust the transmit power with P... CMAXCompare. If so... Figure 28 P like that PSFCH,one +10·log 10 (N) max The value of ) is greater than P CMAX The UE selects a PSFCH based on priority. Two, three, or four PSFCHs can be selected, and if two PSFCHs are selected, the UE selects based on P... PSFCH,k (i) = P PSFCH,one [dBm] determines the transmit power of each PSFCH. When three or four PSFCHs are selected, the UE determines the transmit power based on P. PSFCH,k (i) = P CMAX -10·log 10 (N) Tx,PSFCH [dBm] determines the transmit power of each in the PSFCH. This is because, when selecting three or more PSFCHs, if P... PSFCH,one If the transmission is executed, it will exceed P. CMAX The UE chooses between two or four PSFCHs. If no dl-P0-PSFCH is provided to the UE, the UE initially selects four PSFCHs, such that N max It is four, and then according to P PSFCH,k (i) = P CMAX -10·log 10 (N) Tx,PSFCH [dBm] determines the transmit power of each PSFCH.

[0484] The following describes a method for a UE supporting SL carrier aggregation to determine PSFCH transmission resources for PSSCH received over multiple carriers. Essentially, PSSCH can be transmitted or received over multiple carriers, and PSFCH is considered to be transmitted or received over the carriers receiving PSSCH. That is, considering... Figure 27 Case 1 describes a method for determining the transmit power of the UE's SL channel in this scenario.

[0485] There may be situations where different configurations are provided for dl-P0-PSFCH for each carrier. For example, in the case of performing SL communication for two carriers, when dl-P0-PSFCH configuration is provided to the first carrier and no dl-P0-PSFCH configuration is provided to the second carrier, the UE determines whether to perform dl-P0-PSFCH configuration for each carrier when determining whether to provide dl-P0-PSFCH configuration information. This corresponds to the condition first determined in [Pseudocode 1], and therefore the subsequent determination of PSFCH transmission power is unclear. Therefore, the UE can determine the PSFCH transmission power by at least one or a combination of the following methods. This method is applied when the UE transmits PSFCH for two or more carriers, and when transmitting PSFCH for one carrier, the UE can operate based on [Pseudocode 1].

[0486] • Method A-1: ​​Provide a dl-P0-PSFCH configuration with the same value for each carrier. Specifically, the dl-P0-PSFCH value that can be configured for the corresponding BWP resource pool of a carrier can be configured to have the same value on multiple carriers. By doing so, the UE can apply the same method for one or more carriers scheduled to send or receive PSFCH [Pseudocode 1].

[0487] • Method A-2: PSFCH transmit power can be allocated by prioritizing carriers configured with dl-P0-PSFCH. If the sum of all transmit powers of the PSFCHs to be transmitted on carriers configured with dl-P0-PSFCH is less than P... CMAX Then the UE can perform transmission by allocating the remaining transmit power to the PSFCH of the carrier for which it has not configured dl-P0-PSFCH. Specifically, the transmit power can be determined by the following equation (3).

[0488] P PSFCH,c2 (i)=P cmax - P tx,c1 – 10 log 10 (N TX,PSFCH,c2 [dBm]…(3)

[0489] P PSFCH,c2 (i) means the transmit power of the k-th PSFCH in a carrier where dl-P0-PSFCH is not configured. tx,c1 This means the sum of the transmit power of all PSFCHs transmitted on a carrier configured with dl-P0-PSFCH. N TX,PSFCH,c2The number of PSFCHs to be transmitted on a carrier without dl-P0-PSFCH configuration is determined by the UE. This number can be equal to or less than the number of PSFCHs scheduled on the corresponding carrier. Priority values ​​may be considered, and the determination can be based on the UE's capability values ​​for transmitting PSFCHs. Priority values ​​can be determined through the SCI used to provide PSFCH scheduling information. Higher priority may mean a smaller priority-related field value in the corresponding SCI field. Alternatively, higher priority may mean a larger priority-related field value in the corresponding SCI field. If the sum of the total transmit power of the PSFCHs to be transmitted on a carrier with dl-P0-PSFCH configuration is equal to or greater than P... CMAX Then the UE can allocate the PSFCH transmission power according to equations such as equation (4).

[0490] P PSFCH,k (i)=P CMAX - 10 log 10 (N TX,PSFCH [dBm]…(4)

[0491] P PSFCH,k (i) means the transmit power of the PSFCH scheduled for each carrier, regardless of the configuration of the dl-P0-PSFCH. TX,PSFCH This means the transmit power of the PSFCHs to be transmitted for all carriers in which the UE operates. This can be equal to or less than the number of scheduled PSFCHs and can be determined based on the UE capability value used by the UE to transmit PSFCHs. Alternatively, when the sum of the total transmit power of the PSFCHs to be transmitted on carriers configured with dl-P0-PSFCH is greater than or equal to P... CMAX In this case, the UE can transmit only the PSFCH to be transmitted on carriers configured with dl-P0-PSFCH, and can also skip PSFCH transmission on carriers not configured with dl-P0-PSFCH. Furthermore, the transmit power adjustment for the PSFCH to be transmitted on carriers configured with dl-P0-PSFCH can be operated based on [pseudocode 1].

[0492] • Method A-3: PSFCH transmit power can be allocated by prioritizing carriers without configured dl-P0-PSFCH. Specifically, as in equation (4), PSFCH transmission is performed by allocating transmit power only to PSFCHs scheduled for carriers without configured dl-P0-PSFCH. In this case, N in equation (4) TX,PSFCHThis means the number of PSFCHs scheduled for carriers without dl-P0-PSFCH configuration. Therefore, for PSFCHs scheduled for carriers with dl-P0-PSFCH configuration, the UE does not perform transmission when at least one PSFCH is scheduled for a carrier without dl-P0-PSFCH configuration, and when no PSFCH is scheduled for a carrier without dl-P0-PSFCH configuration, the UE can determine the transmission power based on [pseudocode 1]. Alternatively, after allocating transmission power by applying equation (4) to PSFCHs scheduled for carriers without dl-P0-PSFCH configuration, the UE can allocate the remaining transmission power to PSFCHs scheduled for carriers with dl-P0-PSFCH configuration, and in this case, [pseudocode 1] is applied. In this case, instead of P cmax Consider P cmax -P tx,c2 And P tx,c2 It is the sum of the transmit power of the PSFCH for carrier scheduling without dl-P0-PSFCH configuration.

[0493] • Method A-4: When no dl-P0-PSFCH is configured for at least one carrier, the UE can also determine the PSFCH transmit power by applying a method such as equation (4) to the carriers configured with dl-P0-PSFCH.

[0494] • Method A-5: It may be possible to apply Method A-2 or Method A-3 by considering PSFCH priority, selecting the carrier with the highest priority, or a carrier comprising many PSFCHs with high priority values, and determining whether dl-P0-PSFCH is configured for the corresponding carrier. Alternatively, it may be possible to apply Method A-2 or Method A-3 by considering the carrier index to determine whether the lowest (or highest) carrier index of dl-P0-PSFCH is configured.

[0495] • Method A-6: When the configured dl-P0-PSFCH has different values ​​even when dl-P0-PSFCH is configured for each carrier, it may be possible to sequentially allocate PSFCH transmit power by prioritizing the carrier configured with the largest dl-P0-PSFCH value. For example, when there are a total of four carriers and the dl-P0-PSFCH values ​​are configured in descending order of the first carrier, second carrier, third carrier, and fourth carrier, the transmit power of the PSFCH scheduled for the first carrier is determined. The sum of the transmit powers of the PSFCH scheduled for the first carrier does not exceed P. CMAX When the sum of the transmission powers of the PSFCH scheduled for the first and second carriers does not exceed P, the transmission power of the PSFCH is determined. CMAXWhen the transmit power of the PSFCH scheduled for the third carrier is determined, the transmit power is determined. The sum of the transmit powers of the PSFCHs scheduled for the first, second, and third carriers does not exceed P. CMAX When the transmit power of the PSFCH scheduled for the fourth carrier is determined, the transmit power is determined. When the sum of the transmit powers of the PSFCHs scheduled for the first carrier does not exceed P... CMAX When the sum of the transmission powers of the PSFCH scheduled for the first and second carriers does not exceed P, the transmission power of the PSFCH is determined. CMAX At that time, the UE can make P... CMAX It can be prevented from being overtaken, or P can be made possible by selecting only some PSFCHs with high priority. CMAX It will not be exceeded. Furthermore, the UE does not transmit PSFCH scheduled for the third and fourth carriers. In the example above, four carriers are assumed, but two or more carriers can be configured, and it is possible to sequentially allocate PSFCH transmission power by prioritizing the carrier used to configure the dl-P0-PSFCH with the minimum value.

[0496] • Method A-7: The UE can assume P for each carrier CMAX To apply [pseudocode 1]. That is, when three carriers are configured, the UE can have the same or different P for each carrier. CMAX The PSFCH transmit power is determined simultaneously with the value. Specifically, when P... CMAX When the sum of the transmission powers is used, the maximum transmission power value (P) of each carrier can be determined by the following equation (5). CMAX,c ).

[0497] P CMAX,c =P CMAX - 10 log 10 (N carrier [dBm]…(5)

[0498] N carrier This means the total number of carriers configured or activated by the UE for SL communication. Alternatively, it can be the maximum transmit power value (P) for each carrier. CMAX c) can be determined proportionally to the number of PSFCHs scheduled for each carrier (or the maximum number of PSFCHs indicated by the UE capability report) and can be determined by the following equation (6).

[0499] P CMAX,c =P CMAX - 10 log 10 ( [dBm]…(6)

[0500] N tx This can mean the number of PSFCHs scheduled for all carriers (or the maximum number of PSFCHs the UE can send for all carriers), and N tx,c This could mean the number of PSFCHs scheduled for carrier c (or the maximum number of PSFCHs the UE can send for carrier c).

[0501] The UE can report different maximum numbers of PSFCHs that can be transmitted separately for multiple pools configured for multiple carriers. For example, N for the first carrier. max,1 N of the second carrier max,2 These values ​​can be different from each other. Therefore, in the case of multiple carriers, when the number of PSFCHs scheduled for each carrier exceeds the maximum number of PSFCHs that the UE can support transmitting, a method is required to determine the number of PSFCHs by considering priorities. Therefore, the UE can consider at least one of the following methods to determine the number of PSFCHs to transmit.

[0502] • Method B-1: The UE considers N reported for each carrier max,c And when the number N of PSFCHs scheduled for the corresponding carrier... sch,Tx,c Greater than N max,c When the UE considers priority information, it selects N. max,c There are N PSFCHs. When multiple PSFCHs have the same priority, if it is necessary to select only some PSFCHs, the UE can randomly select only some PSFCHs. max,c This is the maximum number of PSFCHs that a UE can send within the resource pool of carrier c, and it is reported as a UE capability. sch,Tx,c This refers to the number of PSFCHs that the UE will transmit in the resource pool within carrier c. If N is the number of PSFCHs scheduled for the corresponding carrier... sch,Tx,c Equal to or less than N max,c Then the UE can determine whether to transmit N in the corresponding carrier. sch,Tx,c One PSFCH. Figure 29 This illustrates the scenario of scheduling PSFCHs across resource pools on multiple carriers. With 3 PSFCHs scheduled for the first carrier and 4 PSFCHs scheduled for the second carrier, the maximum number of PSFCHs the UE can send on the first carrier is 2, and the maximum number of PSFCHs it can send on the second carrier is 3. Therefore, the UE needs to select the PSFCH with the highest priority on each carrier. Consequently, the PSFCH with the lowest priority on both the first and second carriers is discarded.

[0503] • Method B-2: For N reported for each carrier max,cThe UE can refer to the N of the corresponding carrier. max,c Sum of values ​​N max To select PSFCH. Use Figure 29 To illustrate this, consider the example below. When the maximum number of PSFCHs a UE can transmit on the first carrier is 2, and the maximum number of PSFCHs a UE can transmit on the second carrier is 3, the UE determines that the maximum number of PSFCHs it can transmit on both the first and second carriers is 5. For a total of seven PSFCHs scheduled on the first and second carriers, the UE can select the five PSFCHs with higher priority and transmit them. Therefore, in the same situation, according to method B-1, one PSFCH is discarded for each carrier; however, according to method B-2, there may be cases where only two PSFCHs are discarded on the first carrier or only two PSFCHs are discarded on the second carrier.

[0504] • Method B-3: In addition to the maximum number N of PSFCHs that can be sent per carrier max,c In addition, the UE can also report separately the maximum number N of PSFCHs that can be transmitted simultaneously on multiple carriers. max Unlike method B-2, N max The value can be related to the N of the corresponding carrier. max,c The total number of values ​​may be the same or different. For example, in Figure 29 In N max,1 =2 and N max,2 In the case where N = 3, max It can have a value equal to 5 or a natural value other than 5. Therefore, when scheduling PSFCH only for a specific carrier c, the UE can refer to the maximum number N of PSFCHs that can be transmitted in the corresponding carrier c. max,c PSFCH resources are determined based on priority, and when scheduling PSFCH for multiple carriers, the UE can refer to N. max PSFCH resources are determined based on priority. Additionally, when multiple carriers exist, the same value can be applied to N. max Alternatively, different values ​​can be defined based on the combination of carriers. For example, when configuring a total of three carriers for the UE, the PSFCH can be scheduled for only the first and second carriers, only for the second and third carriers, only for the first and third carriers, and only for the first, second, and third carriers. max These can each have different values, and the UE can determine N related to the combination of carriers that schedules the PSFCH for it, based on the carrier combination. max value.

[0505] • Method B-4: The UE may assume that the maximum number of PSFCHs that can be transmitted in resource pools existing in multiple carriers is always the same for multiple carriers, and report this maximum number. Alternatively, when the maximum number of transmittable PSFCHs reported in a specific carrier c is N max,c And when the number of carriers configured for the UE or in which the UE operates is C, it can be done via C·N. max,c This determines the maximum number of PSFCHs that the UE can send for the corresponding multiple carriers.

[0506] When the number of PSFCHs scheduled for multiple carriers is greater than the maximum transmittable PSFCH or exceeds the maximum transmit power P CMAX In such cases, the UE may need to discard some PSFCHs. The UE can discard lower-priority PSFCHs by considering priorities within the carrier element, or by comprehensively considering multiple carriers and priorities. Specifically, the UE can determine the PSFCHs to be transmitted by considering at least one or a combination of the following methods.

[0507] • Method C-1: The UE can consider carrier-specific priority information to discard PSFCHs with lower priorities. For example, in Figure 29 In the scenario where three PSFCHs are scheduled for the first carrier and four PSFCHs are scheduled for the second carrier, when the maximum number of transmittable PSFCHs in the first carrier is 2 and the maximum number of transmittable PSFCHs in the second carrier is 3, the UE can consider the maximum number of transmittable PSFCHs for each carrier and transmit the PSFCHs with higher priority for each carrier. Furthermore, when the maximum number of transmittable PSFCHs is met and maximum transmit power values ​​are allocated to each carrier, the UE can consider priorities and transmit only the PSFCHs with higher priority. For example, even if two maximum transmittable PSFCHs are selected in the first carrier, if the sum of the transmit power values ​​of the corresponding PSFCHs exceeds the maximum transmit power value allocated to the first carrier (P... CMAX,1 In this case, the UE can also select only the PSFCH with higher priority, and in this case, it can select no more than P. CMAX,1 The maximum PSFCH. The above method is described with reference to the case where each PSFCH has a different priority, but when some PSFCHs have the same priority information, the UE can randomly select a specific PSFCH.

[0508] • Method C-2: The UE can discard PSFCHs with lower priorities based on the priority information of all carriers using PSFCH. For example, in Figure 29In the scenario where three PSFCHs are scheduled for the first carrier and four PSFCHs are scheduled for the second carrier, when the maximum number of PSFCHs the UE can transmit on the first and second carriers is four, the UE can determine the priority information of all PSFCHs scheduled for the first and second carriers and discard PSFCHs with lower priorities. When PSFCHs 1, 2, and 3 on the first carrier have lower priorities than PSFCHs 4, 5, 6, and 7 on the second carrier, all PSFCHs 1, 2, and 3 on the first carrier can be discarded. As another example, the UE can consider the priority of each carrier, the maximum number of PSFCHs that can be transmitted on each carrier, and select PSFCH resources with higher priorities. Figure 29 In the case where PSFCH1 and 2 are selected in the first carrier and PSFCH4, 5, and 6 are selected in the second carrier, the transmit power used to transmit the five PSFCHs may exceed the UE's maximum transmit power (P). CMAX In this case, the UE can consider the priority information of the PSFCH selected in the first carrier and the second carrier to select the PSFCH with higher priority. Specifically, within a range not exceeding P... CMAX In this case, the UE can select the maximum number of PSFCHs. When PSFCH 1 has the lowest priority and the sum of the transmit power values ​​of the remaining PSFCHs 2, 4, 5, and 6 after excluding PSFCH 1 does not exceed P... CMAX At this time, the UE can select PSFCH2, 4, 5 and 6.

[0509] • Method C-3: The UE can consider carrier index information to determine the PSFCH to transmit. When calculating the sum of transmit power values ​​after the UE selects the PSFCH based on priority information according to the maximum transmittable PSFCH, the UE can prioritize according to the ascending or descending order of the determined index of each carrier. For example, in Figure 29 In the case where PSFCH 1 and 2 are selected in the first carrier and PSFCH 4, 5 and 6 are selected in the second carrier, when the transmit power used to transmit the five PSFCHs exceeds the UE's maximum transmit power (P... CMAX When the UE determines which PSFCHs to discard according to the ascending order of the carrier index, the UE can discard each PSFCH with lower priority among the PSFCHs selected in the first carrier 1 and 2, and determine whether the sum of the transmit power values ​​of the remaining PSFCHs exceeds P. CMAX When both PSFCH 1 and 2 are discarded and the sum of the transmit power values ​​of the remaining PSFCHs still exceeds P... CMAX When this happens, the UE discards each PSFCH with lower priority among PSFCHs 4, 5, and 6 of the second carrier, and determines whether the sum of the transmit power values ​​of the remaining PSFCHs exceeds P.CMAX Therefore, the UE can be configured to operate at a speed not exceeding P. CMAX In this case, the UE selects the maximum number of PSFCHs. In the example above, the decision to discard PSFCHs is made in ascending order of the carrier index, but the UE can also decide whether to discard PSFCHs in descending order of the carrier index. Alternatively, when the dl-P0-PSFCH values ​​configured for each carrier are different, the UE can determine whether to start discarding PSFCHs from the carrier with the largest dl-P0-PSFCH value. Alternatively, when the dl-P0-PSFCH values ​​configured for each carrier are different, the UE can determine whether to start discarding PSFCHs from the carrier with the smallest dl-P0-PSFCH value.

[0510] • Method C-4: In the above method, when the sum of the transmit power values ​​of PSFCH exceeds the maximum transmit power (P... CMAX When considering priority information, the primary consideration is discarding lower-priority PSFCHs, while this method is used to transmit PSFCHs by adjusting the transmission power of individual PSFCHs without considering priority information. For example, in Figure 29 In the case where PSFCH 1 and 2 are selected in the first carrier and PSFCH 4, 5 and 6 are selected in the second carrier, when the transmit power used to transmit the five PSFCHs exceeds the UE's maximum transmit power (P... CMAX When N is in the PSFCH, the UE can determine the transmit power of each PSFCH by applying equation (4). In this case, N in equation (4) TX,PSFCH This means the number of PSFCHs selected in the first and second carriers.

[0511] When a UE is configured or scheduled to transmit simultaneously via UL and SL on one or different carriers, if the UE does not have the capability to transmit simultaneously via UL and SL on one or different carriers, the UE will only transmit via the link with the higher priority (i.e., UL or SL).

[0512] When a UE is configured or scheduled to perform transmission via UL and reception via SL on a single carrier, or when a UE is configured or scheduled to perform transmission via UL and reception via SL on different carriers simultaneously, if the UE does not have the capability to perform transmission via UL and reception via SL on different carriers simultaneously, the UE selects only the link with the higher priority. If the UL has a higher priority than the SL, the UE performs only transmission via UL, and if the SL has a higher priority than the UL, the UE performs only reception via SL.

[0513] In cases where the UE can simultaneously perform transmissions via UL and SL on different carriers, the UE is scheduled or configured to perform transmissions via UL and SL on each carrier, with UL transmission resources and SL transmission resources overlapping in specific intervals, and the total UE transmit power value exceeding the UE's maximum transmit power (P) during the corresponding time interval. CMAX When SL transmission has a higher priority than UL transmission, the UE reduces the UL transmission power before starting UL transmission, ensuring that the total UE transmission power does not exceed P. CMAX If UL transmission has a higher priority than SL transmission, the UE reduces the SL transmission power before starting transmission on the start side, ensuring that the total UE transmission power does not exceed P. CMAX .

[0514] For example, the UE can determine the priority between SL transmit / receive and UL transmit by comparing priority threshold information configured via specific higher-layer signals with priority information of the SCI scheduled for SL transmit or receive. When the priority value of the SCI scheduled for SL transmit or receive is less than the priority threshold configured via higher-layer signals, the UE can determine that SL transmit / receive has a higher (or lower) priority than UL transmit. Alternatively, if the priority value of the SCI scheduled for SL transmit or receive is equal to or greater than the priority threshold configured via higher-layer signals, the UE can determine that SL transmit / receive has a higher (or lower) priority than UL transmit.

[0515] When a UE performs SL channel transmission or reception for multiple carriers, and at least some corresponding SL resources overlap with UL channels, the UE may consider at least one or a combination of the following methods to determine the priority between UL and SL.

[0516] • Method D-1: When at least one of the SL channels transmitted or received by the UE in multiple carriers has a priority lower than a priority threshold configured via higher-layer signals, the UE can determine that all SL channels transmitted or received by the UE in the corresponding multiple carriers have a higher (or lower) priority than the UL. If not, the UE can determine that all SL channels transmitted or received by the UE in the corresponding multiple carriers have a lower (or higher) priority than the UL.

[0517] • Method D-2: When at least one of the SL channels transmitted or received by the UE in multiple carriers has a priority equal to or greater than a priority threshold configured via higher-layer signals, the UE can determine that all SL channels transmitted or received by the UE in the corresponding multiple carriers have a priority lower (or higher) than the UL. If not, the UE can determine that all SL channels transmitted or received by the UE in the corresponding multiple carriers have a priority higher (or lower) than the UL.

[0518] • Method D-3: When the priority of a specific carrier's SL channel in multiple carriers transmitted or received by the UE has a priority threshold configured via higher-layer signals, the UE can determine that all SL channels transmitted or received by the UE in the corresponding multiple carriers have a higher (or lower) priority than the UL. If not, the UE can determine that all SL channels transmitted or received by the UE in the corresponding multiple carriers have a lower (or higher) priority than the UL. Specific carriers can be pre-configured via higher-layer signals, or the UE can randomly select specific carriers. Alternatively, the specific carrier can be the same as the UL carrier. Alternatively, the specific carrier can be a carrier with the largest configured dl-P0-PSFCH value. Alternatively, the specific carrier can be a carrier with the smallest dl-P0-PSFCH value.

[0519] • Method D-4: When the priority of the SL channel of a specific carrier in the SL channels transmitted or received by the UE across multiple carriers is equal to or greater than a priority threshold configured via higher-layer signals, the UE can determine that all SL channels transmitted or received by the UE across the corresponding multiple carriers have a lower (or higher) priority than the UL. If not, the UE can determine that all SL channels transmitted or received by the UE across the corresponding multiple carriers have a higher (or lower) priority than the UL. Specific carriers can be pre-configured via higher-layer signals, or the UE can select a carrier with the minimum (or maximum) index value. Alternatively, the specific carrier can correspond to the same carrier as the UL carrier. Alternatively, the specific carrier can be a carrier with the maximum configured dl-P0-PSFCH value. Alternatively, the specific carrier can be a carrier with the minimum dl-P0-PSFCH value.

[0520] • Method D-5: When the sum of the priorities of the SL channels transmitted or received by the UE across multiple carriers is less than a priority threshold configured via higher-layer signaling, the UE can determine that all SL channels transmitted or received by the UE across the corresponding multiple carriers have a higher (or lower) priority than the UL. If not, the UE can determine that all SL channels transmitted or r...

Claims

1. A method performed by a first user equipment (UE) in a wireless communication system, the method comprising: receiving, from a second UE, a plurality of physical sidelink shared channels (PSSCHs) on a first plurality of carriers; and transmitting, to the second UE, a plurality of physical sidelink feedback channels (PSFCHs) on a second plurality of carriers based on a first maximum number of simultaneous PSFCH transmissions in a slot, wherein each of the plurality of PSFCHs corresponds to a respective PSSCH of the plurality of PSSCHs.

2. The method of claim 1, wherein, in case the plurality of PSFCHs are transmitted on a carrier, the plurality of PSFCHs are transmitted based on a second maximum number of simultaneous PSFCH transmissions in a slot.

3. The method of claim 1, wherein, The plurality of PSFCHs are transmitted based on a maximum transmit power (P CMAX ) of the first UE.

4. The method of claim 1, wherein, determining the plurality of PSFCHs to be transmitted based on a priority of the plurality of PSFCHs. 5.A method performed by a second user equipment (UE) in a wireless communication system, the method comprising: transmitting, to a first UE, a plurality of physical sidelink shared channels (PSSCHs) on a first plurality of carriers; and receiving, from the first UE, a plurality of physical sidelink feedback channels (PSFCHs) on a second plurality of carriers based on a first maximum number of simultaneous PSFCH transmissions in a slot, wherein each of the plurality of PSFCHs corresponds to a respective PSSCH of the plurality of PSSCHs.

6. The method of claim 5, wherein, in case the plurality of PSFCHs are transmitted on a carrier, the plurality of PSFCHs are transmitted based on a second maximum number of simultaneous PSFCH transmissions in a slot.

7. The method of claim 5, wherein, The plurality of PSFCHs are transmitted based on a maximum transmit power (P CMAX ) of the first UE.

8. The method of claim 5, wherein, determining the plurality of PSFCHs to be transmitted based on a priority of the plurality of PSFCHs. 9.A first user equipment (UE) in a wireless communication system, the first UE comprising: a transceiver; and a controller coupled to the transceiver; the controller configured to: receive, from a second UE, a plurality of physical sidelink shared channels (PSSCHs) on a first plurality of carriers; and transmit, to the second UE, a plurality of physical sidelink feedback channels (PSFCHs) on a second plurality of carriers based on a first maximum number of simultaneous PSFCH transmissions in a slot, wherein each of the plurality of PSFCHs corresponds to a respective PSSCH of the plurality of PSSCHs.

10. The first UE of claim 9, wherein, in case the plurality of PSFCHs are transmitted on a carrier, the plurality of PSFCHs are transmitted based on a second maximum number of simultaneous PSFCH transmissions in a slot.

11. The first UE of claim 9, wherein, The plurality of PSFCHs are transmitted based on a maximum transmit power (P CMAX ) of the first UE.

12. The first UE of claim 9, wherein, determining the plurality of PSFCHs to be transmitted based on a priority of the plurality of PSFCHs. 13.A second user equipment (UE) in a wireless communication system, the second UE comprising: a transceiver; and a controller coupled to the transceiver; the controller configured to: transmit, to a first UE, a plurality of physical sidelink shared channels (PSSCHs) on a first plurality of carriers; and receive, from the first UE, a plurality of physical sidelink feedback channels (PSFCHs) on a second plurality of carriers based on a first maximum number of simultaneous PSFCH transmissions in a slot, wherein each of the plurality of PSFCHs corresponds to a respective PSSCH of the plurality of PSSCHs. in case the plurality of PSFCHs are transmitted on a carrier, the plurality of PSFCHs are transmitted based on a second maximum number of simultaneous PSFCH transmissions in a slot. Each of the plurality of PSFCHs corresponds to a respective PSSCH of the plurality of PSSCHs.

14. The second UE of claim 13, wherein, In a case that the plurality of PSFCHs are transmitted on a carrier, the plurality of PSFCHs are transmitted based on a second maximum number of simultaneous PSFCH transmissions in a slot.

15. The second UE of claim 13, wherein, The plurality of PSFCHs are transmitted based on a maximum transmit power (P CMAX ) of the first UE.

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