Method and apparatus for providing HARQ feedback in a wireless communication system

Abstract

A method performed by a first terminal in a wireless communication system, the method comprising: obtaining resource pool information associated with a sidelink; transmitting sidelink control information (SCI) associated with sidelink data on a physical sidelink control channel (PSCCH); and transmitting sidelink data on a physical sidelink shared channel (PSSCH) based on the SCI, wherein, in a case where a regional identifier (ID) of the first terminal and information regarding a range requirement are included in the SCI, feedback information associated with the sidelink data is received from a second terminal based on a distance between the first terminal and the second terminal.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for feedback transmission / reception in a wireless communication system. The present disclosure relates to a method and apparatus for providing feedback in a sidelink system such as a device-to-device (D2D) or vehicle-to-everything (V2X) system. Background Art

[0002] To meet the increasing wireless data traffic demand since the deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, 5G or pre-5G communication systems are also referred to as "beyond 4G networks" or "post-LTE systems". The 5G communication system is considered to be implemented in a higher frequency (millimeter wave) band (e.g., 60 GHz band) in order to achieve a higher data rate. To reduce the propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple-input multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large antenna technologies are being discussed in the 5G communication system. In addition, in the 5G communication system, system network improvement is being developed based on advanced small cells, cloud radio access network (RAN), ultra-dense network, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multi-point (CoMP), receiver interference cancellation, etc. In the 5G system, hybrid FSK with QAM modulation (FQAM) and sliding window superimposed coding (SWSC) have been developed as advanced coding modulation (ACM), and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) have been developed as advanced access technologies.

[0003] The Internet, as a human-centric connectivity network in which 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, which is a combination of IoT technology and big data processing technology through connection with a cloud server. Since IoT implementation requires technical elements such as "sensing technology", "wired / wireless communication and network infrastructure", "service interface technology", and "security technology", sensor networks, machine-to-machine (M2M) communication, machine type communication (MTC), etc. have been recently studied. Such an IoT environment can provide intelligent Internet technology services that create new value for human life by collecting and analyzing data generated between interconnected things. IoT can be applied to various fields through the convergence and combined application of existing information technology (IT) and various industrial applications, including smart home, smart building, smart city, smart car or connected car, smart grid, healthcare, smart appliances, and advanced medical services.

[0004] Consistent with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine-type communication (MTC), and machine-to-machine (M2M) communication can be implemented through beamforming, MIMO, and array antennas. The application of cloud radio access network (RAN) as a big data processing technology can also be regarded as an example of the convergence between 5G technology and IoT technology.

[0005] Consistent with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine-type communication (MTC), and machine-to-machine (M2M) communication can be implemented through beamforming, MIMO, and array antennas. The application of cloud radio access network (RAN) as the above-mentioned big data processing technology can also be considered as an example of the convergence of 5G technology and IoT technology. The vehicle-to-everything (hereinafter referred to as V2X) using 5G communication systems is being studied, and it is expected that various services can be provided to users using V2X.

[0006] This information is provided only as background information and is provided to facilitate understanding of the present disclosure. No decision has been made and no claim is made as to whether any of the above can be applied as prior art with respect to the present disclosure. Summary of the Invention

[0007] Technical Problem

[0008] The technical task to be achieved in the embodiments of the present disclosure is to provide a method and apparatus for transmitting or receiving feedback between sidelinks in order to support high reliability and high data rate.

[0009] The technical task to be achieved in the embodiments of the present disclosure is to provide a method and apparatus for providing feedback in a next-generation mobile communication system such as D2D or V2X.

[0010] The technical task to be achieved in the embodiments of the present disclosure is to provide a method and apparatus capable of effectively providing services in a mobile communication system.

[0011] Technical Solution

[0012] An embodiment may provide a method performed by a first terminal in a wireless communication system. The method includes: obtaining resource pool information associated with a sidelink; transmitting sidelink control information (SCI) associated with sidelink data on a physical sidelink control channel (PSCCH); and transmitting sidelink data on a physical sidelink shared channel (PSSCH) based on the SCI, wherein when the area identifier (ID) of the first terminal and information about range requirements are included in the SCI, feedback information associated with the sidelink data is received from a second terminal based on the distance between the first terminal and the second terminal.

[0013] In addition, an embodiment may provide a method performed by a second terminal in a wireless communication system. The method includes: obtaining resource pool information associated with a sidelink; receiving sidelink control information (SCI) associated with sidelink data from a first terminal on a physical sidelink control channel (PSCCH); and receiving sidelink data from the first terminal on a physical sidelink shared channel (PSSCH) based on the SCI, wherein when the area identifier (ID) of the first terminal and information about range requirements are included in the SCI, feedback information associated with the sidelink data is transmitted to the first terminal based on the distance between the first terminal and the second terminal.

[0014] In addition, an embodiment may provide a first terminal in a wireless communication system. The first terminal includes: a transceiver; and a controller configured to:

[0015] obtain resource pool information associated with a sidelink to transmit sidelink control information (SCI) associated with sidelink data on a physical sidelink control channel (PSCCH) via the transceiver; and transmit sidelink data on a physical sidelink shared channel (PSSCH) based on the SCI via the transceiver, wherein when the area identifier (ID) of the first terminal and information about range requirements are included in the SCI, feedback information associated with the sidelink data is received from a second terminal based on the distance between the first terminal and the second terminal.

[0016] In addition, an embodiment may provide a second terminal in a wireless communication system. The second terminal includes: a transceiver; and a controller configured to: obtain resource pool information associated with a sidelink; receive sidelink control information (SCI) associated with sidelink data from a first terminal on a physical sidelink control channel (PSCCH) via the transceiver; and receive sidelink data from the first terminal on a physical sidelink shared channel (PSSCH) based on the SCI via the transceiver, wherein when the area identifier (ID) of the first terminal and information about range requirements are included in the SCI, feedback information associated with the sidelink data is transmitted to the first terminal based on the distance between the first terminal and the second terminal.

[0017] Advantageous Effects of the Invention

[0018] According to embodiments of the present disclosure, an improved communication method and apparatus can be provided in a communication system. According to embodiments of the present disclosure, an improved feedback transmission / reception method and apparatus can be provided in a communication system. According to embodiments of the present disclosure, an improved feedback method and apparatus can be provided in a next-generation mobile communication system, such as D2D or V2X. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To more fully understand the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:

[0020] Figure 1 An example of a system for describing embodiments of the present disclosure is shown;

[0021] Figure 2 An example of a sidelink communication method for describing embodiments of the present disclosure is shown;

[0022] Figure 3 An example of a protocol of a sidelink UE to which embodiments of the present disclosure are applied is shown;

[0023] Figure 4 An example of a sidelink communication procedure according to embodiments of the present disclosure is shown;

[0024] Figure 5 Another example of a sidelink unicast communication procedure according to embodiments of the present disclosure is shown;

[0025] Figure 6 An example of a method for operating hybrid automatic repeat request (HARQ) in sidelink multicast communication according to embodiments of the present disclosure is shown;

[0026] Figure 7 Another example of a method for operating HARQ in sidelink multicast communication according to embodiments of the present disclosure is shown;

[0027] Figure 8 An example of a method for using a region ID in sidelink communication according to embodiments of the present disclosure is shown;

[0028] Figure 9 An example of a problem in HARQ operation using a region ID in sidelink communication according to embodiments of the present disclosure is shown;

[0029] Figure 10 Another example of a problem in HARQ operation using a region ID in sidelink communication according to embodiments of the present disclosure is shown;

[0030] Figure 11 An embodiment of a method for calculating a region ID in distance-based side-link HARQ operations according to an embodiment of the present disclosure is shown;

[0031] Figure 12 Another embodiment for transmitting the location information of a transmitting UE according to an embodiment of the present disclosure is shown;

[0032] Figure 13 Another embodiment for transmitting the location information of a transmitting UE according to an embodiment of the present disclosure is shown;

[0033] Figure 14 Another embodiment for transmitting the location information of a transmitting UE according to an embodiment of the present disclosure is shown;

[0034] Figure 15 is a diagram showing the structure of a transmitting UE according to an embodiment of the present disclosure;

[0035] Figure 16 is a diagram showing the structure of a receiving UE according to an embodiment of the present disclosure; and

[0036] Figure 17 is a diagram showing the structure of a transmitting base station according to an embodiment of the present disclosure. Detailed Description of the Embodiments

[0037] The following discussion Figures 1 to 17 and the various embodiments for describing the principles of the present disclosure in this patent document are for illustrative purposes only and should not be construed in any way as limiting the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any suitably arranged system or device.

[0038] Advantages and features of the present disclosure and its implementation will become apparent by referring to the embodiments described in detail below with reference to the accompanying drawings. However, the present disclosure can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. To fully disclose the scope of the present disclosure to those skilled in the art, and the present disclosure is limited only by the scope of the claims.

[0039] It should be understood that the various boxes of 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 device to produce a machine, such that the instructions executed via the processor of the computer or other programmable data processing device produce means for implementing the functions specified in one or more of the flowchart boxes. These computer program instructions can also be stored in a computer-usable or computer-readable memory, the memory can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-usable or computer-readable memory produce an article of manufacture including instruction means for implementing the functions specified in one or more of the flowchart boxes. The computer program instructions can also be loaded onto a computer or other programmable data processing device to cause a series of operations to be performed on the computer or other programmable device, thereby producing a computer-implemented process, such that the instructions executed on the computer or other programmable device provide operations for implementing the functions specified in one or more of the flowchart boxes.

[0040] And the various boxes of the flowchart illustration can represent modules, segments, or portions of code that include one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions noted in the boxes can occur out of order. For example, two boxes shown in succession can in fact be executed substantially concurrently, or the boxes can sometimes be executed in the reverse order, depending upon the functionality involved.

[0041] As used herein, the term "unit" can refer to a software component, a hardware component, or a device that performs a particular task, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). A unit can be configured to be located on an addressable storage medium and configured to execute on one or more processors. Thus, a module or unit can include, by way of example, components such as software components, object-oriented software components, class components, and task components, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided by the components and modules / units can be combined into fewer components and modules / units or further divided into additional components and modules.

[0042] In the following description, terms used for convenience to identify access nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, terms referring to various identification information, etc. are used illustratively. Thus, the present disclosure is not limited to the terms used hereinafter, and other terms regarding subject matter having equivalent technical meanings can be used.

[0043] For convenience of description, in the following description, the present disclosure uses terms and names defined in 5G, New Radio (NR), or LTE system standards. However, the present disclosure is not limited to these terms and names and can be applied to systems conforming to other standards in the same manner.

[0044] That is, communication standards defined by 3GPP will be mainly described in the detailed description of embodiments of the present disclosure. However, based on the decision of those skilled in the art, the main idea of the present disclosure can be applied to other communication systems with a similar background with some modifications without significantly departing from the scope of the present disclosure.

[0045] In the present disclosure, a transmitting UE refers to a UE that transmits sidelink control information and data information and is a UE that receives HARQ feedback information. A receiving UE refers to a UE that receives sidelink control information and data information. A receiving UE refers to a UE that receives the location information of the transmitting UE and calculates the distance between the transmitting UE and itself (the receiving UE) based on the received location information to determine whether to transmit HARQ feedback. A receiving UE refers to a UE that transmits HARQ feedback information based on the above determination. In the present disclosure, the transmitting UE can be used in combination with a D2D transmitting UE and a V2X transmitting UE, and the receiving UE can be used as a D2D receiving UE and a V2X receiving UE. In the present disclosure, the transmitting UE and the receiving UE are terms used to distinguish a UE that transmits data from a UE that receives data, and a UE is not always limited to the transmitting UE or the receiving UE in the present disclosure. When a specific UE is used to transmit sidelink control information and data information, the specific UE can operate as the transmitting UE described in the present disclosure, and when a specific UE is used to receive sidelink control information and data, the specific UE can operate as the receiving UE described in the present disclosure. When a specific UE is used to transmit sidelink HARQ feedback information, the specific UE can operate as the transmitting UE described in the present disclosure, and when a specific UE is used to receive sidelink HARQ feedback information, the specific UE operates as the receiving UE described in the present disclosure.

[0046] Figure 1 An example of a system for describing embodiments of the present disclosure is shown.

[0047] Figure 1(a) shows an example of a situation (in-coverage scenario) where all V2X UEs (UE-1 and UE-2) are within the coverage area of a base station (gNB / evolved Node B (eNB) / Road Side Unit (RSU)). All V2X UEs (UE-1 and UE-2) can receive data and control information from the base station (gNB / eNB / RSU) via the downlink (DL), or can send data and control information to the base station via the uplink (UL). The data and control information can be data and control information for V2X communication, or can be data and control information for general cellular communication that is not V2X communication. In Figure 1 (a), the V2X UEs (UE-1 and UE-2) can send or receive data and control information for V2X communication via the sidelink (SL).

[0048] Figure 1 (b) shows an example of a situation (partial coverage) where UE-1 among the V2X UEs is within the coverage area of the base station (gNB / eNB / RSU) and UE-2 is outside the coverage area of the base station (gNB / eNB / RSU). UE-1, which is within the coverage area of the base station, can receive data and control information from the base station via the DL, or can send data and control information to the base station via the UL. UE-2, which is outside the coverage area of the base station, cannot receive data and control information from the base station via the downlink and cannot send data and control information to the base station via the uplink. UE-2 can send or receive data and control information for V2X communication via UE-1 and the sidelink (SL).

[0049] Figure 1 (c) shows an example of a situation where all V2X UEs (UE-1 and UE-2) are outside the coverage area of the base station (gNB / eNB / RSU). Therefore, UE-1 and UE-2 cannot receive data and control information from the base station via the DL and cannot send data and control information to the base station via the UL. UE-1 and UE-2 can send / receive data and control information for V2X communication via the sidelink (SL).

[0050] Figure 1Figure (d) shows an example of a scenario where the V2X transmitting UE and the V2X receiving UE are connected to different base stations (gNB / eNB / RSU) (radio resource control (RRC) connected state) or a scenario where the V2X transmitting UE and the V2X receiving UE are camped (RRC disconnected state, i.e., RRC idle state) (inter-cell V2X communication). UE-1 can be the V2X transmitting UE and UE-2 can be the V2X receiving UE. Alternatively, UE-1 can be the V2X receiving UE and UE-2 can be the V2X transmitting UE. UE-1 can receive the V2X dedicated system information block (SIB) from the base station to which UE-1 is connected (or where UE-1 is camped), and UE-2 can receive the V2X dedicated SIB from another base station to which UE-2 is connected (or where UE-2 is camped). The information of the V2X dedicated SIB received by UE-1 and the information of the V2X dedicated SIB received by UE-2 may be different from each other. Therefore, in order to perform D2D V2X communication at different cells, unified information is required.

[0051] In Figure 1 For the convenience of description, a V2X system including two UEs (UE-1 and UE-2) is taken as an example for description. However, the V2X system is not limited thereto, and various numbers of UEs can participate in the V2X system. The uplink (UL) and downlink (DL) between the base station (eNB / gNB / RSU) and the V2X UEs (UE-1 and UE-2) can be referred to as the Uu interface, and the sidelink SL between the V2X UEs (UE-1 and UE-2) can be referred to as the PC5 interface. Therefore, in the present disclosure, it is pre-stated that these terms can be used interchangeably.

[0052] In the present disclosure, a UE can refer to a UE supporting sidelink communication, a UE supporting device-to-device (D2D) communication, a vehicle supporting vehicle-to-vehicle (V2V) communication, a vehicle or a pedestrian's mobile phone (e.g., a smart phone) supporting vehicle-to-pedestrian (V2P) communication, a vehicle supporting vehicle-to-network (V2N) communication, or a vehicle supporting vehicle-to-infrastructure (V2I) communication. In the present disclosure, a UE can refer to an RSU equipped with UE functions, an RSU equipped with base station functions, or an RSU equipped with some base station functions and some UE functions.

[0053] Figure 2 Figure shows an example of a sidelink communication method for describing embodiments of the present disclosure.

[0054] As Figure 2 shown in Figure (a), the transmitting UE and the receiving UE can perform one-to-one communication, and this can be referred to as unicast communication.

[0055] As Figure 2For the transmission in (b), the transmitting UE and the receiving UE can perform one-to-many communication, and this can be referred to as multicast or broadcast. Figure 2 Figure (b) shows that UE-1, UE-2, and UE-3 form a group (Group A) for multicast communication, and shows that UE-4, UE-5, UE-6, and UE-7 form another group (Group B) for multicast communication. Each UE can perform multicast communication only within the group to which each UE belongs, and unicast, multicast, or broadcast communication can be performed between different groups. Figure 2 Figure (b) shows the formation of two groups, but is not limited to this, and a larger number of groups can be formed.

[0056] Although Figure 2 not shown in the figure, the sidelink UE can perform broadcast communication. Broadcast communication refers to the situation where all sidelink UEs (e.g., multiple UEs within the range capable of sidelink communication) receive data and control information sent by the sidelink transmitting UE via the sidelink. For example, if it is assumed that Figure 2 UE-1 in Figure (b) is the transmitting UE for broadcast, then all UEs (UE-2, UE-3, UE-4, UE-5, UE-6, and UE-7) can receive the data and control information sent by UE-1.

[0057] The sidelink unicast, multicast, and broadcast communication methods according to the embodiments can be supported in scenarios of in-coverage, partial coverage, and out-of-coverage.

[0058] In NR sidelink communication, different from LTE sidelink communication, transmission types where a vehicle UE supports sending data to only one specific UE via unicast and transmission types where sending data to a specific number of UEs via multicast can be considered. For example, when considering service scenarios such as vehicle platooning (vehicle platooning is a technology for moving two or more vehicles in a vehicle group by connecting two or more vehicles with one network), such unicast and multicast technologies may be useful. Specifically, unicast communication may be required for purposes such as controlling a specific UE by the leader UE of the group connected by vehicle platooning, and multicast communication may be required for the purpose of simultaneously controlling a specific number of UEs.

[0059] In the NR sidelink system, resource allocation can be performed as follows.

[0060] (1) Mode 1 resource allocation

[0061] Mode 1 resource allocation refers to the method of resource allocation scheduled by the base station (scheduled resource allocation). More specifically, in Mode 1 resource allocation, the base station can allocate resources for sidelink transmission to the RRC-connected UE in a dedicated scheduling method. The base station is capable of managing the resources of the sidelink, such that the scheduled resource allocation method can effectively perform interference management and resource pool management (dynamic allocation and / or semi-persistent transmission). If there is data to be sent to other UEs, the RRC-connected UE can send information indicating the existence of data to be sent to other UEs to the base station by using an RRC message or a Media Access Control (MAC) Control Element (CE). For example, the RRC message can be a Sidelink UE Information message or a UE Assistance Information message. The MAC CE can correspond to a Scheduling Request (SR) and a Buffer Status Report (BSR) MAC CE, including at least one of information about the size of the data buffered for sidelink communication and an indicator notifying the BSR of V2X communication. The sidelink transmitting UE receives the resources scheduled by the base station, and thus when the V2X transmitting UE is within the coverage of the base station, the method of Mode 1 resource allocation can be applied.

[0062] (2) Mode 2 resource allocation

[0063] In Mode 2, the sidelink transmitting UE can autonomously select resources (UE autonomous resource selection). More specifically, Mode 2 corresponds to the method of providing a sidelink transmission / reception resource pool for the sidelink to the UE by the base station as system information or an RRC message (e.g., an RRC reconfiguration message or a PC5-RRC message), where the transmitting UE that has received the transmission / reception resource pool selects a resource pool and resources according to a predetermined rule. In the above example, the base station provides the configuration information of the sidelink transmission / reception resource pool, and when the sidelink transmitting UE and the receiving UE are within the coverage of the base station, Mode 2 can be applied. If the sidelink transmitting UE and the receiving UE are outside the coverage of the base station, the sidelink transmitting UE and the receiving UE can perform Mode 2 operations in a pre-configured transmission / reception resource pool. The UE autonomous resource selection method can include area mapping, sensing-based resource selection, random selection, etc.

[0064] (3) In addition, even if the UE is within the coverage of the base station, resource allocation or resource selection may not be performed in the scheduled resource allocation or UE autonomous resource selection mode, and in this case, the UE can perform sidelink communication via a pre-configured sidelink transmission / reception resource pool (pre-configured resource pool).

[0065] The sidelink resource allocation method according to the above embodiments of the present disclosure can be applied to various embodiments of the present disclosure.

[0066] Figure 3 An embodiment of the protocol of the sidelink UE to which the embodiments of the present disclosure are applied is shown.

[0067] Although Figure 3 not shown in, the application layers of UE-A and UE-B may perform service discovery. Service discovery may include discovering the V2X communication schemes (unicast, multicast, or broadcast) to be performed by each UE. Thus, in Figure 3 it may be assumed that UE-A and UE-B have been identified as performing a unicast communication scheme via the service discovery process performed in the application layer. More specifically, in the application layer, operations related to group management, group ID, quality of service (QoS), etc. may be performed. Although Figure 3 not shown in, the V2X layer may convert the group ID received from the application layer into a destination layer-2 ID (destination L2 ID), and may assign its own transmitter layer-2 ID (source L2 ID). If the V2X layer cannot receive the group ID from the application layer, the V2X layer may determine the destination L2 ID according to the default mapping. The V2X layer generates tag information to distinguish multicast and broadcast traffic, and may include the tag information in the protocol data unit (PDU) or service data unit (SDU) of the V2X layer. By transmitting the above information to the access stratum (AS) layer, the V2X layer may obtain information about the transmitter L2 ID (source identifier) and the destination L2 ID (destination identifier) for V2X communication between V2X UEs.

[0068] When the above process is completed, Figure 3 the PC5 signaling protocol layer shown in may perform a D2D direct link connection establishment process. At this time, security configuration information for D2D direct communication may be exchanged.

[0069] When the D2D direct link connection establishment is completed, a D2D PC5 radio resource control (RRC) configuration process may be performed in the Figure 3 PC5 RRC layer of. Information about the capabilities of UE-A and UE-B may be exchanged, and AS layer parameter information for unicast communication may be exchanged.

[0070] When the PC5 RRC configuration process is completed, UE-A and UE-B may perform unicast communication.

[0071] In the above example, unicast communication is taken as an example for illustration, but it may also be extended to multicast communication. For example, when Figure 3When UE-A, UE-B, and UE-C not shown in the figure perform multicast communication, as described above, UE-A and UE-B can perform direct link establishment for unicast communication D2D, PC5 RRC configuration process, and service discovery. In addition, UE-A and UE-C can also perform D2D direct link establishment for unicast communication, PC5 RRC establishment process, and service discovery. UE-B and UE-C can perform D2D direct link establishment for unicast communication, PC5 RRC establishment process, and service discovery. That is, the PC5 RRC configuration process for unicast communication can be performed by each pair of transmitting UE and receiving UE participating in the multicast communication, rather than performing a separate PC5 RRC configuration process for the multicast communication. However, it is not always necessary to perform the PC5 RRC configuration process for unicast communication in the multicast method. For example, there may be a scenario where multicast communication is performed without establishing a PC5 RRC connection, and in this case, the PC5 connection establishment process for unicast transmission can be omitted.

[0072] Figure 4 An example of a sidelink communication process according to an embodiment of the present disclosure is shown.

[0073] More specifically, Figure 4 Shows a sidelink communication process based on Figure 2 the pattern 1 resource allocation described in. In Figure 4In this case, the base station (eNB / gNB / RSU) can send parameters for sidelink communication to the transmitting and receiving UEs in the cell via system information. The parameters for sidelink communication can be configured in the UEs that have received the system information. For example, the base station can configure information about the resource pool for V2X communication that can be carried out in the cell of the base station. The resource pool can refer to the transmission resource pool for V2X transmission, or can refer to the reception resource pool for V2X reception. The V2X UE can receive information about one or more resource pools from the base station and can configure information about one or more resource pools. The base station can configure unicast, multicast, and broadcast communications to be carried out in different resource pools via system information. For example, resource pool 1 can be used for unicast communication, resource pool 2 can be used for multicast, and resource pool 3 can be used for broadcast communication. Another example is that the base station can be configured such that unicast, multicast, and broadcast communications can be carried out in the same resource pool. Another example is that different resource pools can be configured according to whether there are resources of the physical sidelink feedback channel (PSFCH) for sending sidelink feedback information in the resource pool. More specifically, resource pool 1 can be the pool in which there are PSFCH resources, and resource pool 2 can be the pool in which there are no PSFCH resources. Multicast data and sidelink unicast that require hybrid automatic repeat and request (HARQ) feedback can use resource pool 1, and multicast data, broadcast data, and sidelink unicast that do not require HARQ feedback can use resource pool 2.

[0074] The resource pool information configured by the base station can include at least one of the following pieces of information.

[0075] 1. Information about the time resources in the resource pool: Specifically, the information can include the slot index in which the physical sidelink control channel (PSCCH), physical sidelink shared channel (PSSCH), and physical sidelink feedback channel (PSFCH) are transmitted, or can include the slot indices for transmitting the PSCCH, PSSCH, and PSFCH, and can include the symbol index in the corresponding slot. In addition, the period of the resources for transmitting the PSCCH, PSSCH, and PSFCH can be included. (At least one of the above pieces of information can be included.)

[0076] 2. Information about the frequency resources of the resource pool: This information refers to the information on the frequency axis in the resource pool where the PSCCH, PSSCH, and PSFCH can be transmitted, and specifically can include the resource block index that constitutes the resource pool or the index of a sub-channel containing two or more resource blocks. (At least one of the above pieces of information can be included.)

[0077] 3. The resource pool configuration information can contain information about whether to operate sidelink HARQ-ACK.

[0078] (1) For the case of operating the sidelink HARQ-ACK, it may include at least one of the following pieces of information.

[0079] (1-1) Maximum number of retransmissions

[0080] (1-2) HARQ-ACK timing: HARQ-ACK timing refers to the time point from when the V2X receiving UE receives sidelink control information and data information from the V2X transmitting UE to when the V2X receiving UE sends the relevant HARQ-ACK / NACK information to the V2X transmitting UE. The time unit can be a time slot or one or more OFDM symbols.

[0081] (1-3) PSFCH format or HARQ feedback method: When operating two or more PSFCH formats, one PSFCH format can be used to send HARQ-ACK / NACK information consisting of 1 bit or 2 bits. Another PSFCH format can be used to send HARQ-ACK / NACK information consisting of 3 bits or more bits. If the aforementioned HARQ-ACK / NACK information is sent via the PSFCH, each of the ACK information and the NACK information can be sent via the PSFCH. When the decoding of the PSSCH sent by the V2X transmitting UE is successful, the V2X receiving UE can send an ACK via the PSFCH. When the decoding fails, a NACK can be sent via the PSFCH. For example, the V2X receiving UE may not send an ACK when the decoding of the PSSCH sent by the V2X transmitting UE is successful and may send a NACK via the PSFCH only when the decoding fails. Alternatively, when operating one PSFCH format, information about the aforementioned HARQ feedback method (whether each of the ACK information and the NACK information will be sent via the PSFCH or only the NACK information will be sent via the PSFCH) can be included.

[0082] (1-4) Time / frequency / code resources or resource set constituting the PSFCH: In the case of time resources, it may include the time slot index for sending the PSFCH, or may include the symbol index and period. In the case of frequency resources, it may include the frequency block (RB: resource block) via which the PSFCH is sent or the start and end points of a subchannel including two or more consecutive blocks (or the start point and length of the frequency resource).

[0083] (2) If the sidelink HARQ-ACK is not operated, the above information can be excluded from the resource pool configuration information.

[0084] 4. The resource pool configuration information may include information on whether blind retransmission is operated.

[0085] (1) Different from the retransmission based on HARQ-ACK / NACK, blind retransmission may mean that the transmitting UE repeats the transmission without receiving the feedback information of ACK or NACK from the receiving UE. If blind retransmission is operated, the number of blind retransmissions can be included in the resource pool information. For example, if the number of blind retransmissions is configured to 4, the transmitting UE can always send the same information 4 times when sending PSCCH / PSSCH to the receiving UE. The redundancy version (RV) value can be included in the sidelink control information (SCI) sent via PSCCH. If blind retransmission is not operated, the above information can be excluded from the resource pool configuration information.

[0086] 5. The resource pool configuration information may include information about the demodulation reference signal (DMRS) pattern that can be used in the PSSCH sent from the corresponding resource pool.

[0087] (1) The DMRS pattern that can be used in the PSSCH may vary according to the speed of the UE. For example, if the speed is high, it is necessary to increase the number of OFDM symbols used for DMRS transmission on the time axis to improve the accuracy of channel estimation. If the speed of the UE is low, even if a small number of DMRS symbols are used, the accuracy of channel estimation can be guaranteed. Therefore, it is necessary to reduce the number of OFDM symbols used for DMRS transmission on the time axis to reduce the DMRS overhead. Therefore, the information about the resource pool may include information about the DMRS pattern that can be used in the corresponding resource pool. Two or more DMRS patterns are configured in a resource pool, and the V2X transmitting UE can select and use one DMRS pattern from the configured DMRS patterns according to the speed of the V2X transmitting UE. The V2X transmitting UE can send information about the selected DMRS pattern to the V2X receiving UE via the SCI of PSCCH. The V2X receiving UE can receive this information to obtain the DMRS pattern information, can perform channel estimation of the PSSCH, and can obtain the sidelink data information via the demodulation and decoding process.

[0088] 6. The resource pool configuration information may include information about whether to operate the sidelink channel state information reference signal (CSI-RS).

[0089] (1) If the sidelink CSI-RS is operated, at least one of the following information can be included.

[0090] (1-1) CSI-RS transmission start time: The CSI-RS transmission start time may refer to the start time when the V2X transmitting UE should send the CSI-RS to the V2X receiving UE. The start time may refer to the index of the time slot for sending the CSI-RS, or may refer to the index of the symbol for sending the CSI-RS, or both the index of the time slot and the symbol.

[0091] (1-2) CSI reporting timing: CSI reporting timing refers to the time from the time point when the UE in V2X reception receives CSI-RS from the UE in V2X transmission (i.e., the slot index when CSI-RS is received, or the symbol index in the slot used for reception) to the time point when the UE in V2X reception sends a CSI report to the UE in V2X transmission (i.e., the slot index when the CSI report is sent, or the symbol index in the slot index used for transmission). The unit representing time can be a slot or one or more OFDM symbols.

[0092] (2) If the sidelink CSI-RS is not operated, this information can be excluded from the resource pool configuration information.

[0093] 7. The resource pool configuration information may include parameters for controlling the sidelink transmission power. (At least one of the following parameters)

[0094] (1) Sidelink transmission power control may require an estimate of the sidelink path attenuation value. If the Uu carrier of the base station and the sidelink carrier are the same, in order to reduce the interference to the uplink signal received at the receiving end of the base station caused by sidelink transmission, the sidelink transmission power control can be operated based on the downlink path attenuation estimate value. For this purpose, the base station can configure whether the V2X transmitting UE should configure the sidelink transmission power value based on the sidelink path attenuation estimate value, configure whether the V2X transmitting UE should configure the sidelink transmission power value based on the downlink path attenuation estimate value, or configure whether the V2X transmitting UE should configure the sidelink transmission power value by considering both the sidelink path attenuation estimate value and the downlink path attenuation estimate value. For example, if the base station configures the SSB or downlink CSI-RS as the signal to be used for path attenuation estimation, the UE can configure the sidelink transmission power value based on the downlink path attenuation value. If the base station configures the sidelink demodulation reference signal (DMRS) or sidelink CSI-RS as the signal to be used for path attenuation estimation, the UE can configure the sidelink transmission power value based on the sidelink path attenuation value.

[0095] (2) As described above, different transmission power parameters can be configured according to the signal used for path attenuation estimation.

[0096] Although the above information is shown as being included in the resource pool configuration for V2X communication, the present disclosure is not limited thereto. That is, the above information can be configured by the V2X transmitting UE or the V2X receiving UE independently of the resource pool configuration.

[0097] As Figure 4As shown, when generating data to be sent from the V2X transmitting UE to the V2X receiving UE, the V2X transmitting UE may request sidelink resources for sending data to the V2X receiving UE from the base station by using a scheduling request (SR) or / and a buffer status report (BSR). The base station that has received the SR or / and BSR may confirm that the V2X transmitting UE has data for sidelink transmission and may determine the resources required for sidelink transmission based on the SR or / and BSR.

[0098] The base station sends a sidelink scheduling grant to the V2X transmitting UE, and the sidelink scheduling grant includes at least one of resource information for sidelink control information (SCI) transmission, resource information for sidelink data transmission, and resource information for sidelink feedback transmission. The sidelink scheduling grant is information for authorizing dynamic scheduling in the sidelink and may be downlink control information (DCI) sent on the physical downlink control channel (PDCCH). If the base station is an NR base station, the sidelink scheduling grant may include information indicating the bandwidth part (BWP) for sidelink transmission and a carrier frequency indicator or carrier indicator field (CIF) for sidelink transmission. If the base station is an LTE base station, only the CIF may be included. The sidelink scheduling grant may also include feedback information for sidelink data, that is, resource allocation-related information of the physical sidelink feedback channel (PSFCH) for sending ACK / NACK information. The resource allocation information may include information for allocating multiple PSFCH resources to multiple UEs in a group when the sidelink transmission is multicast. The resource allocation-related information of the feedback information may be information indicating at least one of multiple sets of feedback information resource candidates configured via higher layer signaling.

[0099] The V2X transmitting UE that has received the sidelink scheduling grant sends SCI for scheduling sidelink data to the V2X receiving UE on the physical sidelink control channel (PSCCH) according to the sidelink scheduling grant, and sends the sidelink data scheduled by the SCI to the V2X receiving UE on the physical sidelink shared channel (PSSCH). The SCI may include at least one of the following: resource allocation information for sidelink data transmission, modulation and coding scheme (MCS) information applied to sidelink data, group destination ID information, transmitter ID (source ID) information, unicast destination ID information, power control information for controlling sidelink power, timing advance (TA) information, DMRS configuration information for sidelink transmission, information related to packet retransmission, such as information about the number of times of packet retransmission, information related to resource allocation when performing packet retransmission, redundancy version (RV), and HARQ process ID. The SCI may also include feedback information for sidelink data, that is, information indicating the resource for sending ACK / NACK information.

[0100] The V2X receiving UE that has received the SCI receives sidelink data based on the information included in the SCI. Thereafter, the V2X receiving UE sends ACK / NACK information indicating whether the decoding of the sidelink data is successful or failed to the V2X transmitting UE on the Physical Sidelink Feedback Channel (PSFCH). The transmission of the feedback information of the sidelink can be applied to unicast transmission or multicast transmission, but the case of applying it to broadcast transmission is not excluded. If the sidelink transmission corresponds to multicast transmission, each UE that has received the multicast data can send feedback information by using different PSFCH resources. Alternatively, each UE that has received the multicast data can send feedback information by using the same resource PSFCH, and at this time, only NACK information can be fed back. That is, the UE that has received the data can not give feedback in the case of ACK, and only give feedback in the case of NACK. The PSFCH resources can include not only resources classified in the time domain or / and frequency domain, but also resources classified by using codes such as scrambling codes and orthogonal cover codes, and resources classified by using different sequences and cyclic shifts applied to different sequences.

[0101] The base station can configure the V2X transmitting UE to report the HARQ feedback received from the V2X receiving UE based on the system information or RRC. In this case, the V2X transmitting UE can send the sidelink HARQ feedback received from the V2X receiving UE to the base station via the Physical Uplink Control Channel (PUCCH) or the Physical Uplink Shared Channel (PUSCH). The base station can configure whether the V2X transmitting UE can multiplex and transmit the sidelink HARQ feedback information received from the V2X receiving UE and the uplink control information (UCI) for the existing Uu.

[0102] If the base station does not configure the multiplexing of the sidelink HARQ feedback information and the UCI information, the V2X transmitting UE cannot multiplex the sidelink HARQ feedback information and the uplink control information (UCI) information for the Uu and send the multiplexed information on one PUCCH. In this case, the base station can independently configure the PUCCH for transmitting the sidelink HARQ feedback information and the PUCCH for transmitting the UCI information. That is, the PUCCH for transmitting the sidelink HARQ feedback information exists independently, and UCI information cannot be transmitted in the corresponding PUCCH.

[0103] Alternatively, when the base station configures the multiplexing of sidelink HARQ feedback information and UCI information, the V2X transmitting UE can multiplex the sidelink HARQ feedback information and UCI information so as to transmit the multiplexed information via one PUCCH. When the sidelink HARQ feedback information is assumed to be N1 bits and the UCI information is assumed to be N2 bits, the multiplexing order can follow N2+N1 (i.e., multiplex the sidelink HARQ feedback information after the UCI information). If the code rate of the sum of the sidelink HARQ feedback bits and UCI bits multiplexed and transmitted via the PUCCH is greater than the code rate configured by the base station, the V2X transmitting UE can discard the transmission of the sidelink HARQ feedback information (i.e., discard the sidelink HARQ feedback information). If the V2X transmitting UE discards the transmission of the sidelink HARQ feedback information, the sidelink HARQ feedback information can be transmitted on another PUCCH resource, or can be multiplexed with other UCI bits and transmitted on another PUCCH resource.

[0104] In Figure 4 it is assumed a scenario where the V2X transmitting UE has established an uplink connection to the base station (i.e., RRC connected state) and both the V2X transmitting UE and the V2X receiving UE are within the coverage area of the base station. Although Figure 4 not shown, if the V2X transmitting UE has not established an uplink connection to the base station (i.e., RRC standby (idle) state), the V2X transmitting UE can perform a random access procedure to establish an uplink connection to the base station. Although Figure 4 not shown, in a scenario where the V2X transmitting UE is within the coverage area of the base station and the V2X receiving UE is outside the coverage area of the base station, the V2X receiving UE can pre-receive and use the above information for V2X communication. As Figure 4 shown, for the V2X transmitting UE, the information for V2X communication can be configured by the base station. If both the V2X transmitting UE and the V2X receiving UE are outside the coverage area of the base station, the V2X transmitting UE and the V2X receiving UE can pre-receive and use the above information for V2X communication. Here, the meaning of pre-configuration can be interpreted as using the value embedded in the UE at the time of UE factory shipment. Another meaning of pre-configuration can be interpreted as using the pre-configured value according to the information configured by the UE at a specific time. Another meaning of pre-configuration can refer to using the information for V2X communication that has been pre-acquired via RRC configuration by accessing the base station by the V2X transmitting UE or the V2X receiving UE, or using the information for V2X communication newly obtained via the system information of the base station.

[0105] Although Figure 4Not shown. It can be assumed that before the V2X transmitting UE sends an SR / BSR to the base station, the processes of service discovery with the V2X receiving UE, D2D direct link connection establishment, and PC5 RRC configuration have been completed by the processes mentioned in Figure 3 as mentioned above.

[0106] Figure 5 Another example of a sidelink unicast communication process according to an embodiment of the present disclosure is shown.

[0107] More specifically, Figure 5 shows a V2X communication process based on the mode 2 resource allocation described in Figure 2 . In Figure 5 , the base station can configure parameters for V2X communication for the V2X transmitting UE and the V2X receiving UE in the cell based on the system information. The parameters can include at least one piece of parameter information shown in Figure 4 .

[0108] As shown in Figure 5 , when generating data to be sent by the V2X transmitting UE to the V2X receiving UE, the V2X transmitting UE sends an SCI to the V2X receiving UE on the PSCCH and sidelink data to the V2X receiving UE on the PSSCH. The SCI can also include at least one of the following: resource allocation information for sidelink data transmission, MCS information applied to the sidelink data, group destination ID information, transmitter ID information, unicast destination ID information, power control information for controlling sidelink power, timing advance information, DMRS configuration information for sidelink transmission, information related to packet retransmission, such as information about the number of times of packet retransmission, information related to resource allocation when performing packet retransmission, redundancy version (RV), and HARQ process ID. The SCI can also include information indicating a resource for feedback information (A / N information) for sending the sidelink data.

[0109] The V2X receiving UE that has received the SCI receives the sidelink data on the receiving side. The V2X receiving UE can receive the sidelink data on the PSSSCH based on the SCI. Thereafter, the V2X receiving UE sends ACK / NACK information indicating whether the decoding of the sidelink data indicating the sending side is successful or failed on the PSFCH to the V2X sending UE. The sending of the feedback information for the sidelink can be applied to unicast sending or multicast sending, but the case of applying it to broadcast sending is not excluded. If the sidelink sending corresponds to multicast sending, each UE that has received the multicast data can send the feedback information by using different resources, the PSFCH. Alternatively, each UE that has received the multicast data can send the feedback information by using the same resource, the PSFCH, and at this time, only NACK information can be fed back (that is, if the UE that has received the data determines ACK, no feedback is provided). The PSFCH resources can include not only the resources classified in the time domain or / and frequency domain, but also the resources classified by using codes such as scrambling codes and orthogonal cover codes, and the resources classified by using different sequences and cyclic shifts applied to different sequences.

[0110] As Figure 4 shown, Figure 5 the base station in

[0111] can configure the V2X sending UE to report the HARQ feedback received from the V2X receiving UE based on the system information or RRC. In this case, the V2X sending UE can send the sidelink HARQ feedback received from the V2X receiving UE to the base station via the physical uplink control channel (PUCCH) or the physical uplink shared channel (PUSCH). The base station can configure whether the V2X sending UE can multiplex and send the sidelink HARQ feedback information received from the V2X receiving UE and the uplink control information (UCI) for the existing Uu.

[0112] Alternatively, when the base station configures the multiplexing of sidelink HARQ feedback information and UCI information, the V2X transmitting UE can multiplex the sidelink HARQ feedback information and UCI information so as to transmit the multiplexed information via one PUCCH. When the sidelink HARQ feedback information is assumed to be N1 bits and the UCI information is assumed to be N2 bits, the multiplexing order can follow N2+N1 (i.e., multiplex the sidelink HARQ feedback information after the UCI information). If the code rate of the sum of the sidelink HARQ feedback bits and UCI bits multiplexed and transmitted via the PUCCH is greater than the code rate configured by the base station, the V2X transmitting UE can discard the transmission of the sidelink HARQ feedback information (i.e., discard the sidelink HARQ feedback information). If the V2X transmitting UE discards the transmission of the sidelink HARQ feedback information, the sidelink HARQ feedback information can be transmitted on another PUCCH resource, or can be multiplexed with other UCI bits and transmitted on another PUCCH resource.

[0113] In Figure 5 , a scenario is assumed where both the V2X transmitting UE and the receiving UE are within the coverage area of the base station. Although Figure 5 not shown, when both the V2X transmitting UE and the receiving UE are outside the coverage area of the base station, Figure 5 can also be applied. In this case, the V2X transmitting UE and the receiving UE can pre-receive the configuration of the above information for V2X communication. Although Figure 5 not shown, Figure 5 it can also be applied to a scenario where one of the V2X transmitting UE and the V2X receiving UE is within the coverage area of the base station and the other UE is outside the coverage area of the base station. In this case, the UE within the coverage area of the base station can receive the information configured by the base station for V2X communication, and the UE outside the coverage area of the base station can receive the pre-configured information for V2X communication. In the above examples, the "information for V2X communication" can be interpreted as Figure 4 the information of at least one of the parameters for V2X communication mentioned in

[0114] Although Figure 5 not shown, it can be assumed that before the V2X transmitting UE sends the PSCCH / PSSCH to the V2X receiving UE, it has been by Figure 3The processes mentioned in [0] complete service discovery with the V2X receiving UE, the direct link establishment process, and the PC5 RRC configuration process.

[0115] In Figure 5 unicast communication where only one V2X transmitting UE exists is described as an example, but it can also be applied to multicast communication and broadcast communication where two or more V2X transmitting UEs exist.

[0116] Figure 6 An embodiment of a method for operating HARQ in V2X multicast communication according to an embodiment of the present disclosure is shown.

[0117] Figure 6 A scenario is shown where the transmitting UE and the receiving UE are within the coverage area of the base station and thus the transmitting UE and the receiving UE can receive system information for sidelink communication from the base station. Parameters for sidelink communication can be configured in the UE that has received the system information. When the transmitting UE and the receiving UE are outside the coverage area of the base station ( Figure 1 a scenario outside the coverage area of

[13] ), the transmitting UE and the receiving UE can have parameters for sidelink communication that are pre-configured or configured via a sidelink master information block (SL-MIB) sent through the sidelink synchronization channel.

[0118] Before multicast communication, all transmitting UEs and receiving UEs in the same group can perform PC5 RRC connection establishment via the Figure 3 unicast link establishment process described in

[18] . However, there may be a scenario where multicast communication is performed without PC5 RRC connection establishment. In this scenario, the Figure 6 shown unicast link establishment process can be omitted. Although Figure 6 shows the unicast link establishment process after receiving the system parameter configuration information from the base station, the unicast link establishment process can be performed first and then the system parameter configuration information can be received. If there is no base station, after performing the unicast link establishment process, parameters for sidelink communication can be configured via the SL-MIB.

[0119] When Figure 4 the mode-1 resource allocation scheme shown in

[28] is used for Figure 6 , the base station can send sidelink scheduling information to the multicast transmitting UE via the physical downlink control channel (PDCCH). The transmitting UE that has received the information can send sidelink control information and data information to the receiving UE via the PSCCH and PSSCH respectively using the scheduling information of the base station. As Figure 3As described, the destination identifier (e.g., destination L2 ID) and the transmission identifier (e.g., transmitter L2 ID) can be included in the PSCCH for transmission. One-bit information regarding whether to activate or deactivate the HARQ operation can be included. More specifically, even if the resource pool configuration information includes the PSFCH resource configuration information for the HARQ operation (e.g., PSFCH period), when the SCI includes information indicating the deactivation of the HARQ operation, the transmitting UE can deactivate the HARQ operation. The reasons are as follows.

[0120] In the case of broadcast communication, the sidelink control information and data information are transmitted to multiple unspecified UEs, and thus the HARQ operation in broadcast communication may be difficult. In the case of unicast and multicast communication, the HARQ operation can be configured or not configured according to the QoS of the transmitted sidelink data. For example, some specific sidelink data has a relatively high requirement for reception reliability, and thus the HARQ operation can be configured. However, other specific sidelink data does not have a relatively high requirement for reception reliability, and thus the HARQ operation can be not configured. Another example is that some specific sidelink data has a relatively high requirement for the latency in sidelink communication (i.e., the latency time should be short), and thus the HARQ operation can be not configured. However, other specific sidelink data does not have a relatively high requirement for the latency time (i.e., the latency time can be long), and thus the HARQ operation can be configured. As described above, the HARQ operation can be configured or cancelled according to the QoS of the sidelink data transmitted by the transmitting UE. The determination of whether to configure the HARQ operation can vary according to the QoS, and thus this determination can be made in the application layer that manages the QoS or in the V2X layer that has received the QoS from the application.

[0121] However, in this case, the HARQ operation of the receiving UE may be impossible. More specifically, the HARQ operation should be performed in the PHY / MAC layer, but if the V2X layer or the application layer, etc., controls the HARQ operation, the HARQ operation cannot be performed in the PHY / MAC layer of the receiving UE. That is, the PHY / MAC layer of the receiving UE should know whether to operate HARQ before delivering the corresponding packet to the V2X layer or the application layer of the receiving UE, and based on this, HARQ combining can be performed in the PHY layer. Therefore, for the HARQ operation of the PHY / MAC layer, the transmitting UE can include a one-bit indicator indicating whether to operate HARQ via the SCI.

[0122] As Figure 5 shown, the mode-2 resource allocation scheme can be used in Figure 6 . In this case, the PDCCH of Figure 6 can be omitted.

[0123] A receiving UE that has received a PSCCH and a PSSCH from a transmitting UE can determine whether the destination L2 ID included in the SCI of the PSCCH refers to itself, and when the destination L2 ID refers to itself, can decode the PSSCH based on the time and / or frequency resource allocation information of the PSSCH included in the SCI. Based on the PSSCH decoding, the receiving UE can finally determine whether the sidelink data is sent to itself via the destination L2 ID included in the MAC-CE sent via the PSSCH. That is to say, the destination L2 ID consists of N bits, and N1 bits can be sent via the SCI, and the remaining N2 bits can be sent via the MAC-CE (N = N1 + N2). If it is determined that the destination L2 ID included in the received SCI does not refer to itself (the receiving UE), the receiving UE can not decode the PSSCH indicated by the SCI.

[0124] If the PSCCH and PSSCH sent from the transmitting UE refer to the destination L2 ID of the receiving UE, the receiving UE can send HARQ-ACK (if the decoding is successful) and HARQ-NACK (if the decoding fails) to the transmitting UE, depending on whether the decoding of the received PSSCH is successful.

[0125] If the HARQ feedback information received from multiple receiving UEs includes at least one HARQ-NACK information, the transmitting UE that has received the HARQ feedback information can retransmit the PSSCH. If all the HARQ feedback information received from all receiving UEs is HARQ-ACK, the transmitting UE that has received the same feedback information can not retransmit the PSSCH. That is to say, the transmitting UE does not retransmit the data that has been sent, and when new sidelink data to be sent is generated, the transmitting UE can send a new PSSCH. If no new sidelink data to be sent is generated, the transmitting UE can stop sending the PSSCH.

[0126] As Figure 6 shown, the transmitting UE can send the sidelink HARQ feedback information received from the receiving UE to the base station according to the configuration of the base station. Here, the sidelink HARQ feedback information can be sent via the PUCCH or the PUSCH, and the specific operation can follow Figure 4 and Figure 5 one of the methods described in

[0127] For HARQ operations in multicast, the transmitting UE may need to know information about the receiving UEs in the same group. For example, for sidelink HARQ operations, the transmitting UE should identify sidelink HARQ feedback information sent from different receiving UEs. That is, the transmitting UE may need to determine which receiving UE has sent HARQ-ACK and which receiving UE has sent HARQ-NACK. Therefore, Figure 6 The sidelink HARQ operation method shown can be applied to the case where unicast link connections are established between all transmitting UEs and receiving UEs in a group. However, in the case where unicast link connections are not established between all transmitting UEs and receiving UEs in a group, Figure 6 it cannot be applied. The HARQ operation method for this will be described in Figure 7 .

[0128] Figure 7 Another embodiment of a method for operating HARQ in sidelink multicast communication according to an embodiment of the present disclosure is shown.

[0129] As Figure 6 shown, Figure 7 the transmitting UE and the receiving UE in Figure 1 can receive system information for sidelink communication from the base station. Parameters for sidelink communication can be configured in the UEs that have received the system information. When the transmitting UE and the receiving UE are outside the coverage of the base station ( Figure 1 in a scenario outside the coverage), the transmitting UE and the receiving UE can have parameters for sidelink communication that are pre-configured or configured via a sidelink master information block (SL-MIB) sent through a sidelink synchronization channel.

[0130] Figure 7 is a method for sidelink HARQ operation in a multicast communication scenario without PC5 RRC connection establishment. Therefore, the process of establishing a unicast link between the transmitting UE and the receiving UE can be omitted. However, the HARQ operation method of Figure 7 can also be applied even when the unicast link establishment process is performed between the transmitting UE and the receiving UE. In this scenario, the unicast link establishment process shown in Figure 7 can be included. Although Figure 7 shows the unicast link establishment process after receiving the system parameter configuration information from the base station, the unicast link establishment process can be performed first and then the system parameter configuration information can be received. If there is no base station, after performing the unicast link establishment process, parameters for sidelink communication can be configured via the SL-MIB.

[0131] Figure 6 The difference between Figure 7 and Figure 7The transmitting UE and the receiving UE therein can calculate their own location information. The location information may refer to the ID of the area including the UE or may refer to the coordinates (x, y) of the UE, which are calculated based on the latitude and longitude of the UE, but is not limited thereto.

[0132] When Figure 4 the pattern-1 resource allocation scheme shown is used for Figure 7 , the base station can send sidelink scheduling information to the multicast transmitting UE via the physical downlink control channel (PDCCH). The transmitting UE that has received the sidelink scheduling information via the PDCCH can send sidelink control information and data information to the receiving UE via the PSCCH and the PSSCH respectively by using the scheduling information. As Figure 3 mentioned, the destination L2 ID and the transmitter L2 ID can be included in the PSCCH for transmission. One-bit information regarding whether to activate or deactivate the HARQ operation can be included. More specifically, even if the resource pool configuration information includes the PSFCH resource configuration (e.g., PSFCH period) information for the HARQ operation, the transmitting UE can deactivate the HARQ operation by adding information indicating the deactivation of the HARQ operation to the SCI. The reasons are as follows.

[0133] In the case of broadcast communication, the sidelink control information and the data information are sent to multiple unspecified UEs, and thus the HARQ operation in broadcast communication may be difficult. In the case of unicast and multicast communication, the HARQ operation can be configured or not configured according to the QoS of the transmitted sidelink data. For example, some specific sidelink data has a high level of requirement for reception reliability, and thus the HARQ operation can be configured. However, other specific sidelink data does not have a high level of requirement for reception reliability, and thus the HARQ operation can be not configured. Also, some specific sidelink data has a high level of requirement for the latency in sidelink communication (that is, the latency time should be short), and thus the HARQ operation can be not configured. However, other specific sidelink data does not have a high level of requirement for the latency time (that is, the latency time can be long), and thus the HARQ operation can be configured. As described above, the HARQ operation can be configured or cancelled according to the QoS of the sidelink data transmitted by the transmitting UE. The determination regarding whether to configure the HARQ operation can vary according to the QoS, and thus the determination can be made in the application layer that manages the QoS or in the V2X layer that has received the QoS from the application.

[0134] However, in this case, HARQ operations at the receiving UE may not be possible. More specifically, HARQ operations should be performed in the PHY / MAC layer, but if the HARQ operations are controlled by layers such as the V2X layer or the application layer, the HARQ operations cannot be performed in the PHY / MAC layer of the receiving UE. That is to say, the PHY / MAC layer of the receiving UE should know whether to operate HARQ before delivering the corresponding packet to the V2X layer or the application layer of the receiving UE, and based on this, HARQ combining can be performed in the PHY layer. Therefore, for HARQ operations in the PHY / MAC layer, the transmitting UE can include a 1-bit indicator indicating whether to operate HARQ via the SCI.

[0135] As Figure 5 shown, a pattern-2 resource allocation scheme can be used in Figure 7 . In this case, the operation in which the transmitting UE receives scheduling information from the base station via the PDCCH can be omitted. Figure 7

[0136] In addition to the above information, the transmitting UE can also add its own location information and the range requirement of the sidelink data packet transmitted thereby to the transmitted SCI, and can transmit the SCI via the PSCCH. The range requirement is not limited to being received via the SCI, and a pre-configured value can be used for the UE, or a value configured by the base station can be used. The location information of the transmitting UE can refer to the ID of the area where the transmitting UE is located, or can refer to the coordinates (x, y) of the transmitting UE, which are calculated based on the latitude and longitude of the transmitting UE, but is not limited thereto. The range requirement can be expressed in meters, and can refer to the information of the distance over which the sidelink data packet should be transmitted. For example, the range requirement can refer to at least one of the maximum or minimum distance over which the sidelink data packet should be transmitted.

[0137] The receiving UE that has received the PSCCH and the PSSCH can determine whether the destination L2 ID included in the SCI of the PSCCH refers to itself, and when the destination L2 ID refers to itself (the receiving UE), can decode the PSSCH based on the time and / or frequency resource allocation information of the PSSCH included in the SCI. Based on the PSSCH decoding, the receiving UE can finally determine whether the sidelink data is sent to itself via the destination L2 ID included in the MAC-CE transmitted via the PSSCH. That is to say, the above destination L2 ID consists of N bits, and N1 bits can be transmitted via the SCI, and the remaining N2 bits can be transmitted via the MAC-CE (N = N1 + N2). If it is determined that the destination L2 ID included in the received SCI does not refer to itself (the receiving UE), the receiving UE can not decode the PSSCH indicated by the SCI.

[0138] If the PSCCH and PSSCH sent from the transmitting UE refer to the destination L2ID of the receiving UE, the receiving UE can calculate the distance between the transmitting UE and itself (the receiving UE) based on its own location information and the location information of the transmitting UE received from the transmitting UE (including in the SCI information of the PSCCH). The distance between the transmitting UE and the receiving UE-N is defined as d N . The receiving UE can compare the d TH value with the d TH value via the range requirement (defined as d N ) included in the SCI information of the received PSCCH. The receiving UE can perform HARQ operations according to the comparison result of the d TH and d N values. For example, if the distance between the transmitting UE and the receiving UE measured (calculated or obtained) by the receiving UE is greater than (or greater than or equal to) the range requirement, the receiving UE may not send HARQ feedback information to the transmitting UE, regardless of whether the received PSSCH is successfully decoded. That is, when d N > d TH or d N ≥ d TH , the receiving UE may not provide HARQ feedback. Alternatively, when d N ≤ d TH or d N < d TH , the receiving UE can send HARQ feedback to the transmitting UE. The receiving UE can send HARQ-NACK to the transmitting UE only when the decoding of the PSSCH fails. That is, even if the distance condition is met, when the decoding of the PSSCH is successful, HARQ-ACK may not be sent to the transmitting UE. Figure 7 Fig. shows an example of a case where the receiving UE-1 sends HARQ-NACK to the transmitting UE via the PSFCH.

[0139] If two or more receiving UEs meet the conditions (i.e., d N ≤ d TH or d N < d TH)If the PSSCH decoding fails, two or more receiving UEs may send HARQ-NACK to the sending UE. The time / frequency / code resources of the PSFCH used by two or more receiving UEs for HARQ-NACK transmission may be the same. Therefore, the sending UE that has received the HARQ feedback information does not need to know the number of receiving UEs that have sent NACK information, and the sending UE that has received the NACK information may retransmit the PSSCH. If the sending UE does not receive the NACK information and new sidelink data to be newly transmitted is generated, the sending UE may send a new PSSCH. If no new sidelink data to be newly transmitted is generated, the sending UE may stop PSSCH transmission.

[0140] As Figure 7 shown, the sending UE may send the sidelink HARQ feedback information received from the receiving UE to the base station according to the configuration of the base station. Here, the sidelink HARQ feedback information may be sent via the PUCCH or the PUSCH, and the specific operation may follow Figure 4 and Figure 5 one of the methods described therein.

[0141] Whether to use the Figure 6 sidelink HARQ operation or the Figure 7 sidelink HARQ operation in multicast communication may be included in the resource pool configuration information configured by the base station, or may be included in the pre-configured resource pool configuration information when there is no base station. Also, whether to apply Figure 6 and Figure 7 may be implicitly or explicitly indicated by the sending UE via the SCI. As an example of implicit indication, when the location information and range request information of the sending UE are included in the SCI, the receiving UE may indirectly identify that the Figure 7 method should be used. When the location information and range request information of the sending UE are not included in the SCI, the receiving UE may implicitly identify that the Figure 6 method should be used. As an example of explicit indication, the sending UE may add a 1-bit indicator to the SCI to send the indicator. If the indicator indicates "1", the UE that has received the indicator may apply the Figure 6 method, and if the indicator indicates "0", the Figure 7 method may be applied. Depending on the configuration, it may be configured to apply the Figure 6 method when the indicator indicates "0", and the Figure 7 method may be applied when the indicator indicates "1".

[0142] Figure 8 shows an embodiment of a method of using a region ID in sidelink communication according to an embodiment of the present disclosure.

[0143] The base station may send zone configuration information to the sidelink UE in the cell via the SL-ZoneConfig information element (IE) based on the V2X system information. The SL-ZoneConfig IE may include parameters such as the width of the zone ( Figure 8 W in the zoneWidth, indicating the length of the area ( Figure 8 The zoneIdLongiMod parameter indicates the number of zones configured based on longitude, and the zoneIdLatiMode parameter indicates the number of zones configured based on latitude. Each of the zoneWidth and zoneLength parameters can be configured to one of 5m, 10m, 20m, 50m, 100m, 200m, and 500m. Each of the zoneIdLongiMod and zoneIdLatiMode parameters can be configured to an integer from 1 to 4.

[0144] That is to say, for Figure 8 The horizontal A km and vertical B km configurations of the zones, the horizontal and vertical sizes of each zone and the number of zones contained in (A x B) km can be configured using the parameters in the SL-ZoneConfig IE, which are configured by the base station (if there is no base station, this configuration can be done in advance).

[0145] If the base station configures two or more sidelink transmission resource pools (if there is no base station, two or more sidelink transmission resource pools are pre-configured), the area ID may be included in the configured transmission resource pool information. For example, if two sidelink transmission resource pools are configured from the base station (or pre-configured), area ID = 3 may correspond to transmission resource pool 1, and area ID = 7 may correspond to transmission resource pool 2. The UE may calculate the area ID information to be used by itself based on the following [Equation 1], and may use such a transmission resource pool in which the area ID calculated by the UE and the area ID included in the resource pool information configured by the base station (or the area ID included in the pre-configured resource pool information) are the same.

[0146] [Equation 1]

[0147] x1=Floor(x / L)Mod Nx;

[0148] y1=Floor(y / W)Mod Ny;

[0149] Area ID = y1*Nx+x1

[0150] In [Equation 1], L and W are parameters corresponding to zoneLength and zoneWidth respectively, and Nx and Ny are parameters corresponding to zoneIdLongiMod and zoneIdLatiMod respectively. In addition, x may refer to the difference between the current longitude position of the UE and the coordinates (0, 0) of the reference point (x, y), and y may refer to the difference between the current latitude position of the UE and the coordinates (0, 0) of the reference point (x, y). For the reference point (0, 0), a unique coordinate in the world can be configured, such as the location of the Greenwich Observatory.

[0151] Figure 9 An example of a problem in HARQ operations using zone IDs in sidelink communication according to an embodiment of the present disclosure is shown.

[0152] For Figure 7 the HARQ operation based on the distance between the transmitting UE and the receiving UE mentioned in, the transmitting UE sends its own zone ID information to the receiving UE and should simultaneously send a range requirement to the receiving UE. The zone ID information indicates the index of the zone, and the range requirement is expressed in "meters". In this case, the receiving UE can determine whether to send HARQ-NACK feedback by converting the range requirement sent by the transmitting UE via the SCI into a zone, or the receiving UE can estimate the location of the transmitting UE from the zone ID provided by the transmitting UE via the SCI, can estimate the distance between the transmitting UE and itself (the receiving UE), and can determine whether to send HARQ-NACK feedback via comparison with the range requirement.

[0153] When the receiving UE converts the range requirement sent by the transmitting UE into a zone, the receiving UE can feed back HARQ-NACK information to the transmitting UE only when the difference between the zone ID provided by the transmitting UE and the zone ID to which the receiving UE itself belongs has a value less than or equal to a certain value. If the difference between the zone ID provided by the transmitting UE and the zone ID to which the receiving UE itself belongs has a value greater than or equal to a certain value, the receiving UE may not send HARQ feedback to the transmitting UE. For example, assume that the receiving UE should feed back HARQ-NACK information to the transmitting UE only when the difference between the zone ID of the transmitting UE and the zone ID of the receiving UE has a value less than 3. In this case, as Figure 9 shown, ambiguity may occur when the transmitting UE is located in zone 4 and the receiving UE is located in zone 7. That is, since the difference between the zone ID of the transmitting UE and the zone ID of the receiving UE is 3, the receiving UE does not send HARQ feedback to the transmitting UE. However, as Figure 9As shown, the transmitting UE and the receiving UE may actually be in very close proximity, and it may be desirable for the receiving UE to send HARQ feedback to the transmitting UE. Thus, in such a case, an ambiguity may occur in the HARQ operation mentioned in Figure 7 .

[0154] When the receiving UE estimates the distance between the region ID of the transmitting UE and itself (the receiving UE) and compares the distance with the range requirement to determine whether to send HARQ-NACK feedback, the receiving UE should measure the distance between the transmitting UE and the receiving UE based on its own current location and the region ID information received from the transmitting UE. As Figure 9 shown, an ambiguity may occur in measuring the distance between the transmitting UE and the receiving UE. For example, if the transmitting UE is located in region 5 and the receiving UE is located in another region 5, the receiving UE cannot know from the region 5 in Figure 9 which region 5 the transmitting UE is located in (that is, there are four region 5s in Figure 9 ). Thus, the receiving UE cannot determine whether the distance to the transmitting UE meets the range requirement.

[0155] A solution to the above problem is needed.

[0156] Figure 10 Another example of the problem in HARQ operation using region ID in sidelink communication according to an embodiment of the present disclosure is shown.

[0157] When the receiving UE estimates the distance between the region ID of the transmitting UE and itself (the receiving UE) and compares the distance with the range requirement to determine whether to send HARQ-NACK feedback, the receiving UE should measure the distance between the transmitting UE and the receiving UE based on its own current location and the region ID information received from the transmitting UE. As Figure 10 shown, an ambiguity may occur in measuring the distance between the transmitting UE and the receiving UE. For example, assume that the transmitting UE sends its own region ID (ID = 5) to the receiving UE via the SCI of the PSCCH. The transmitting UE may be located in the northwest of region 5, as Figure 10 shown. However, the receiving UE does not know the exact location of the transmitting UE, and thus may need to make an assumption about the location of the transmitting UE in the corresponding region for distance calculation.

[0158] For example, the receiving UE may assume that the transmitting UE is located at the center of the area (where the area ID = 5). As another example, the receiving UE may assume that the vertex in the area where the transmitting UE is located that is farthest from the receiving UE's own position is the position of the transmitting UE. More specifically, assume that the coordinates of the four vertices of area 5 are (a1, b1), (a2, b2), (a3, b3), and (a4, b4) respectively. And assume that the position of the receiving UE is (x, y). The receiving UE can calculate the distances from each vertex coordinate to its own based on the coordinates of the four vertices and its own coordinates (x, y), and can assume that the vertex coordinate with the longest distance corresponds to the position of the transmitting UE. The closest vertex can apply the above example. That is, it can be assumed that the vertex in the area where the transmitting UE is located that is closest to (or has the shortest distance from) the receiving UE's own position is the position of the transmitting UE.

[0159] As another example, the receiving UE can assume the position of the transmitting UE by translating the coordinates of the area where the transmitting UE is located to the area where the receiving UE is located. For example, as Figure 10 shown, assume that the transmitting UE is located in area 5 and the receiving UE is located in area 9. And assume that W = 50m and L = 10m. The receiving UE can assume that the transmitting UE is located at (x - 50, y - 10) based on its own position (x, y) in area 9.

[0160] Figure 11 An embodiment of a method for calculating an area ID in distance-based sidelink HARQ operations according to an embodiment of the present disclosure is shown.

[0161] Figure 11 is a method for solving problems in the case where the transmitting UE and the receiving UE as described in Figure 9 exist in different positions but use the same area ID. In Figure 11 the embodiment of, Figure 9 the problems described in can be solved by configuring the areas such that there are no areas with the same ID. For example, the configuration can be performed in such a way that there are no areas with the same ID.

[0162] Figure 11Shows the W, L, Nx, and Ny parameters that can be configured differently from each other for calculating the region ID for transmission resource pool selection and the W, L, Nx, and Ny parameters for calculating the region ID in distance-based sidelink HARQ operations. More specifically, the base station can send the W1, L1, Nx1, and Ny1 parameters to the transmitting UE via system information or RRC configuration information, so that the transmitting UE calculates the region ID for selecting the transmission resource pool. The base station can send the W2, L2, Nx2, and Ny2 parameters to the sidelink transmitting UE and the sidelink receiving UE via system information or RRC configuration information, so that the transmitting UE and the receiving UE resolve the ambiguity in the sidelink HARQ operation based on the region ID. The W1, L1, Nx1, and Ny1 parameters are different from the W2, L2, Nx2, and Ny2 parameters, and specifically, at least one of the relationships W1≤W2, L1≤L2, Nx1≥Nx2, and Ny1≥Ny2 should be satisfied. That is, a specific region can be made to have regions with different IDs by configuring the W and L values to be large and / or by configuring the Nx and Ny values to be small, as Figure 11 shown.

[0163] For another example, the W1, L1, Nx1, and Ny1 parameters and the W2, L2, Nx2, and Ny2 parameters can be related to each other. More specifically, it can be defined as 1) W1 = α·W2, L1 = β·L2, Nx1 = δ·Nx2, and Ny1 = γ·Ny2, or it can be defined as 2) W2 = α·W1, L2 = β·L1, Nx2 = δ·Nx1, and Ny2 = γ·Ny1. An example of the case of 1) can be α = β = 0.5 and δ = γ = 2. An example of 2) can be α = β = 4 and δ = γ = 1. Although α and β are shown to have the same value, α and β can have different values from each other. Similarly, although δ and γ are shown to have the same value, δ and γ can have different values from each other. As described above, if the W1, L1, Nx1, and Ny1 parameters and the W2, L2, Nx2, and Ny2 parameters are associated with each other via α, β, δ, and γ, the base station can send the configuration information of a set of W1, L1, Nx1, and Ny1 parameters (setting 1) or W2, L2, Nx2, and Ny2 parameters (setting 2) to the sidelink UE. In addition, α, β, δ, and γ can be configured. The information about α, β, δ, and γ can be included in the resource pool configuration information, or fixed values can always be used.

[0164] For another example, there can be a method of adding a region ID field included in the SCI without separately configuring the W1, L1, Nx1, and Ny1 parameters and the W2, L2, Nx2, and Ny2 parameters. More specifically, in Figure 11In (a) of [description], there are nine region IDs from region 1 to region 9, and there are four identical region IDs in each region ID (for example, there are four region IDs where region ID = 5). Therefore, it may take 4 bits to distinguish the region IDs, and it may take 2 bits to distinguish the actual positions of the individual region IDs. In the above example, the transmitting UE can add a total of 6 bits of information to the SCI and can send the SCI to the receiving UE via the PSCCH. The 2 bits for distinguishing the actual position can be the most significant bits (MSB) on the left side of the 6 bits or the least significant bits (LSB) on the right side. The summary is as follows. It can be assumed that a specific region configured by horizontal A km and vertical B km includes M region IDs, and each region ID repeats N times. The transmitting UE adds 2 Floor(M / 2) bits + 2 Floor(N / 2) bits = K bits, which is the sum of the 2 Floor(M / 2) bits for distinguishing the M region IDs and the 2 Floor(N / 2) bits for distinguishing the actual positions of the individual region IDs, and can send the SCI to the receiving UE via the PUCCH. Among the K bits, 2 Floor(N / 2) MSB bits or 2 Floor(N / 2) LSB bits are the bits for distinguishing the actual positions of the individual region IDs, and the remaining bits can be the bits for distinguishing the region IDs. The method of adding the region ID field is not limited to the above embodiments.

[0165] According to the above method, the UE can perform the HARQ feedback operation by reconfiguring the regions so that there are no regions with the same ID. In another embodiment, if the receiving UE and the transmitting UE are in the same region, the HARQ feedback operation is determined by reconfiguring the regions so that there are no regions with the same ID according to the above method. In addition, if the receiving UE and the transmitting UE are in different regions, the HARQ feedback operation can be performed according to the Figure 9 embodiment.

[0166] One of the above methods can be used to solve the Figure 9 ambiguity mentioned, which arises from the fact that the same region ID is used even when the transmitting UE and the receiving UE are in different positions. However, there is a disadvantage that the Figure 9 ambiguity caused when the transmitting UE and the receiving UE use different region IDs but are located close to each other cannot be solved. To solve this problem, one of the methods described in Figure 12 , Figure 13 and Figure 14 can be used.

[0167] Figure 12 Fig. [figure number] shows another example for sending the location information of the transmitting UE according to an embodiment of the present disclosure.

[0168] As Figure 7 shown, Figure 12 the transmitting UE and the receiving UE in Figure 1 can receive system information for sidelink communication from the base station. Parameters for sidelink communication can be configured in the UE that has received the system information. When the transmitting UE and the receiving UE are outside the coverage area of the base station (

[0169] In Figure 12 , the transmitting UE and the receiving UE can calculate their own position coordinates (x, y) periodically or aperiodically via the Global Navigation Satellite System (GNSS). Figure 12 Assume a scenario where a PC5 RRC connection is established between the transmitting UE and the receiving UE in a group performing multicast communication. Therefore, the transmitting UE and the receiving UE can exchange their position coordinates (x, y) during the PC5 RRC connection establishment process.

[0170] Figure 12 shows that the calculation of the UE's position coordinates (x, y) is performed after receiving the system parameter configuration information, but the calculation of the UE's position coordinates (x, y) can be performed first, and the system parameter configuration information can be received later. If there is no base station, the Figure 12 system parameter configuration block can be omitted, and as Figure 3 mentioned in

[0171] When Figure 4 the mode-1 resource allocation scheme shown in Figure 12 is used for Figure 3 , the base station can send sidelink scheduling information to the multicast transmitting UE via the Physical Downlink Control Channel (PDCCH). The transmitting UE that has received the information can send sidelink control information and data information to the receiving UE via the PSCCH and PSSCH respectively using the scheduling information of the base station. As

[0172] In the case of broadcast communication, sidelink control information and data information are sent to multiple unspecified UEs, and thus HARQ operations in broadcast communication may be difficult. In the case of unicast and multicast communication, HARQ operations may or may not be configured according to the QoS of the transmitted sidelink data. For example, some specific sidelink data has a high level of requirement for reception reliability, and thus HARQ operations can be configured. However, other specific sidelink data does not have a high level of requirement for reception reliability, and thus HARQ operations can be not configured. Also, some specific sidelink data has a high level of requirement for latency in sidelink communication (that is, the latency time should be short), and thus HARQ operations can be not configured. However, other specific sidelink data does not have a high level of requirement for the latency time (that is, the latency time can be long), and thus HARQ operations can be configured. As described above, HARQ operations can be configured or cancelled according to the QoS of the sidelink data transmitted by the transmitting UE. The determination of whether to configure HARQ operations can vary according to QoS, and thus this determination can be made in the application layer that manages QoS or in the V2X layer that has received QoS from the application.

[0173] However, in this case, HARQ operations at the receiving UE may be impossible. More specifically, HARQ operations should be performed in the PHY / MAC layer, but if the V2X layer or the application layer, etc., controls HARQ operations, then HARQ operations cannot be performed in the PHY / MAC layer of the receiving UE. That is, the PHY / MAC layer of the receiving UE should know whether to operate HARQ before delivering the corresponding packet to the V2X layer or the application layer of the receiving UE, and based on this, HARQ combining can be performed in the PHY layer. Therefore, for HARQ operations in the PHY / MAC layer, the transmitting UE can include a 1-bit indicator indicating whether to operate HARQ via the SCI.

[0174] As Figure 5 shown, the mode-2 resource allocation scheme can be used in Figure 12 . In this case, the operation of the transmitting UE receiving scheduling information from the base station via the PDCCH can be omitted in Figure 12 .

[0175] In addition to the above information, the transmitting UE may add offset information to the SCI, where the offset information indicates the difference between the coordinates (x, y) of the transmitting UE itself sent to the receiving UE during the establishment of the PC5 RRC connection and the coordinates (x, y) at the time point when the transmitting UE itself sends the current sidelink control information and data information, and may send the SCI via the PSCCH. Also, for example, the transmitting UE may add the offset information to the MAC-CE or MAC-PDU, and may send the MAC-CE or MAC-PDU via the PSSCH. The transmitting UE may determine whether to add the offset information to the SCI or MAC-CE / MAC-PDU based on its own speed or the change amount at (x, y) and (x1, y1). More specifically, if the moving speed of the transmitting UE is higher than or equal to a specific value (i.e., when the moving speed is high), there may be many changes in the position of the transmitting UE. For example, assuming that the moving speed of the transmitting UE is 120 km / h, the transmitting UE may move 33 meters per second. Therefore, in order to accurately measure the distance between the transmitting UE and the receiving UE, the transmitting UE may send the difference between its previous position coordinates (x, y) and the current position coordinates (x1, y1) to the receiving UE via the SCI or MAC-CE / MAC-PDU. Also, for example, regardless of the speed of the transmitting UE, if the difference between the previous position coordinates (x, y) and the current position coordinates (x1, y1) of the transmitting UE has a value greater than or equal to a specific value, the transmitting UE may send the offset value to the receiving UE via the SCI or MAC-CE / MAC-PDU. The offset information or position coordinates may be defined as the position information of the transmitting UE. If the SCI does not include the offset information or information about the position coordinates of the transmitting UE, the receiving UE may determine the position of the transmitting UE based on the previously received position coordinate information.

[0176] The transmitting UE can not only compare the position information during the establishment of the PC5 RRC connection with the position information of the SCI, but also compare the position information of the SCI with the position information of subsequent SCIs. For example, when an SCI is sent and a subsequent SCI is sent to the same receiving UE, the offset value may correspond to the offset value from the position information included in the previous SCI. When determining whether to include the position information of the transmitting UE in the SCI, if the difference between the position coordinates of the transmitting UE when sending the previous SCI and the position coordinates of the transmitting UE when sending the current SCI exceeds a specific value, the new coordinate value or offset value of the transmitting UE may be added, otherwise the new coordinate value or offset value of the transmitting UE may be omitted.

[0177] The transmitting UE may add the coordinate (x1, y1) value at the time point when transmitting the current sidelink control information and data information to the MAC-CE or MAC-PDU instead of the offset information, and may transmit the MAC-CE or MAC-PDU via the PSSCH. This is because, compared with the SCI, the MAC-CE or MAC-PDU can transmit a relatively large number of bits. Therefore, when transmitting the location coordinates of the transmitting UE to the MAC-CE or MAC-PDU, the transmitting UE may transmit the actual coordinate (x1, y1) value to the receiving UE instead of the offset value. That is to say, when the PC5 RRC connection is established, the transmitting UE may transmit its own coordinates (x, y) to the receiving UE, and may add the coordinate (x1, y1) value at the time point when the transmitting UE itself transmits the current sidelink control information and data information or the offset value between (x, y) and (x1, y1) to the MAC-CE or MAC-PDU, and may transmit the MAC-CE or MAC-PDU via the PSSCH. When the distance-based HARQ operation is configured or activated, the coordinate (x1, y1) value at the time point when transmitting the sidelink control information and data information or the offset value between (x, y) and (x1, y1) may be provided. If neither the distance-based HARQ operation is configured nor activated, the coordinate (x1, y1) value at the time point when transmitting the sidelink control information and data information or the offset value between (x, y) and (x1, y1) may not be provided.

[0178] For another example, during the establishment of the PC5 RRC connection, the transmitting UE does not transmit location information (i.e., does not transmit the coordinate (x, y) information when establishing the PC5 RRC connection). If the distance-based HARQ operation is configured or activated, the transmitting UE may add the coordinate (x1, y1) value at the time point when the transmitting UE itself transmits the current sidelink control information and data information to the MAC-CE or MAC-PDU, and may transmit the MAC-CE or MAC-PDU via the PSSCH.

[0179] In addition to the offset information or the coordinate (x1, y1) value, the transmitting UE may add a range request for the sidelink data packet transmitted by it to the SCI, and may transmit the SCI via the PSCCH. The range requirement is not limited to being received via the SCI, and a pre-configured value may be used for the UE, or a value configured by the base station may be used.

[0180] A receiving UE that has received PSCCH and PSSCH from a transmitting UE can determine whether the destination L2 ID included in the SCI of the PSCCH refers to itself, and when the destination L2 ID refers to itself (the receiving UE), it can decode the PSSCH based on the time and / or frequency resource allocation information of the PSSCH included in the SCI. Based on the PSSCH decoding, the receiving UE can finally determine whether the sidelink data is sent to itself via the destination L2 ID included in the MAC-CE sent via the PSSCH. That is to say, the above-mentioned destination L2 ID consists of N bits, and N1 bits can be sent via the SCI, and the remaining N2 bits can be sent via the MAC-CE (N = N1 + N2). If it is determined that the destination L2 ID included in the received SCI does not refer to the receiving UE, the receiving UE can not decode the PSSCH indicated by the SCI.

[0181] If the PSCCH and PSSCH sent from the transmitting UE refer to the destination L2 ID of the receiving UE, the receiving UE can calculate the distance between the transmitting UE and itself based on its own current location information and the location information received from the transmitting UE. The receiving UE can obtain the location information of the transmitting UE via at least one of the above various methods. For example, the receiving UE can obtain the current coordinates (x1, y1) of the transmitting UE by using the coordinates (x, y) sent when the transmitting UE establishes a PC5 RRC connection and the offset information sent via the SCI of the PUCCH or the MAC-CE / MAC-PDU of the PSSCH. Another example is that the receiving UE can obtain the current coordinates (x1, y1) of the transmitting UE sent via the MAC-CE / MAC-PDU of the PSSCH.

[0182] Based on the location information (x1, y1) of the transmitting UE, the receiving UE can calculate the distance between the transmitting UE and itself. The distance between the transmitting UE and the receiving UE-N is defined as d N . The receiving UE can compare the d TH value with the d TH value via the range requirement (defined as d N ) included in the SCI information of the received PSCCH. The receiving UE can perform a HARQ operation according to the comparison result of the d TH and d N values. For example, if the distance between the transmitting UE and the receiving UE measured (calculated or obtained) by the receiving UE is greater than (or greater than or equal to) the range requirement, the receiving UE can not send HARQ feedback information to the transmitting UE, regardless of whether the received PSSCH is successfully decoded. That is to say, when d N ≥ d TH or d N ≥ dTH In this case, the receiving UE may not provide HARQ feedback. Alternatively, when d N ≤d TH or d N <d TH the receiving UE may send HARQ feedback to the transmitting UE. The receiving UE may send a HARQ-NACK to the transmitting UE only when the decoding of the PSSCH fails. That is, even if the distance condition is satisfied, when the decoding of the PSSCH is successful, the HARQ-ACK may not be sent to the transmitting UE. Figure 7 FIG. shows an example of a case where the receiving UE-1 sends a HARQ-NACK to the transmitting UE via the PSFCH. Figure 12 FIG. shows an example of a case where the receiving UE-1 sends a HARQ-NACK to the transmitting UE via the PSFCH.

[0183] If two or more receiving UEs satisfy the condition (i.e., d N ≤d TH or d N <d TH ) and the PSSCH decoding fails, two or more receiving UEs may send a HARQ-NACK to the transmitting UE. The time / frequency / code resources of the PSFCH used by two or more receiving UEs for HARQ-NACK transmission may be the same. Therefore, the transmitting UE that has received the HARQ feedback information does not need to know the number of receiving UEs that have sent NACK information, and the transmitting UE that has received the NACK information may perform retransmission of the PSSCH. If the transmitting UE does not receive the NACK information and there is new sidelink data to be transmitted, the transmitting UE may send a new PSSCH. If there is no new sidelink data to be transmitted, the transmitting UE may stop PSSCH transmission.

[0184] As Figure 12 shown, the transmitting UE may send the sidelink HARQ feedback information received from the receiving UE to the base station according to the configuration of the base station. Here, the sidelink HARQ feedback information may be sent via the PUCCH or the PUSCH, and the specific operation may follow Figure 4 and Figure 5 one of the methods described therein.

[0185] Whether to use the sidelink HARQ operation of Figure 6 or the sidelink HARQ operation of Figure 12 in multicast communication may be included in the resource pool configuration information configured by the base station, or may be included in the pre-configured resource pool configuration information when there is no base station. Also, for example, it may be implicitly or explicitly indicated by the transmitting UE via the SCI whether to apply Figure 6 andFigure 12 。As an example of implicit indication, when the location information and range request information of the transmitting UE are included in the SCI, the receiving UE can indirectly identify the method that should be used Figure 12 . When the location information and range request information of the transmitting UE are not included in the SCI, the receiving UE can implicitly identify the method that should be used Figure 6 . As an example of explicit indication, the transmitting UE can add a 1-bit indicator to the SCI to send the indicator. If the indicator indicates "1", the UE that has received the indicator can apply the method of Figure 6 , and if the indicator indicates "0", the method of Figure 12 can be applied. Depending on the configuration, it can be configured to apply the method of Figure 6 when the indicator indicates "0", and apply the method of Figure 12 when the indicator indicates "1".

[0186] Embodiments that can be applied when the area ID of the transmitting UE is different from the area ID of the receiving UE Figure 12 Embodiments that can also be applied even when the area ID of the transmitting UE is the same as the area ID of the receiving UE Figure 12 can be applied.

[0187] When the determination of whether to perform distance-based HARQ feedback operation cannot be determined via the area ID of the transmitting UE and the area ID of the receiving UE, by further considering the location information, embodiments of Figure 12 can be applied to determine whether to perform distance-based HARQ feedback operation, but it is not limited thereto.

[0188] Figure 13 shows another example for transmitting the location information of the transmitting UE according to an embodiment of the present disclosure.

[0189] When there is no PC5 RRC connection established between sidelink UEs within the same group for group communication, it is not possible as Figure 12As shown, during the PC5 RRC connection establishment process, the location coordinates (x, y) of the transmitting UE are sent to the receiving UE. In this scenario, to operate distance-based sidelink HARQ operations, it is necessary to define the time relationship between the MAC-CE / MAC PDU or RRC message through which the location information is sent and the SCI, MAC-CE / MAC PDU or RRC through which the offset of the location information is sent. More specifically, after [x] milliseconds (ms), [y] time slots, or [z] symbols based on the time point of sending the MAC-CE, MAC PDU, or RRC message (sending the location information of the transmitting UE through the above MAC-CE, MAC PDU, or RRC message), the transmitting UE needs to send an SCI, MAC-CE / MAC PDU, or RRC message that includes the offset value of the location information of the transmitting UE itself. The receiving UE that has received the SCI, MAC-CE / MAC PDU, or RRC message including the offset value of the location information of the transmitting UE can assume that the transmitting UE has sent the location information through the MAC-CE, MAC PDU, or RRC message before [x] ms, [y] time slots, or [z] symbols based on the reception time point of the offset value.

[0190] More specifically, as Figure 13 shown in (a) of, the transmitting UE can send its own location coordinates (x, y) to the receiving UE through a MAC-CE, MAC PDU, or RRC message in time slot "n" (the MAC-CE mentioned below can be replaced by a MAC PDU or RRC message). The MAC-CE including (x, y) of the transmitting UE can be sent at least once during a predetermined time period. That is, the transmitting UE can send the MAC-CE including its own (x, y) at a time configured by the base station, a pre-configured time, or a fixed time period. The transmitting UE can send the MAC-CE a number of times configured by the base station, a pre-configured number of times, or a fixed number of times within the above time period.

[0191] The number of MAC-CE transmissions can be more than once. If the number of MAC-CE transmissions is two or more times, the interval between MAC-CE transmissions can or may not be constant. If the transmission interval is constant, the transmission interval can be configured by the base station, or can be pre-configured (or can be fixed). If the MAC-CE is transmitted two or more times, the MAC-CE can transmit the same location information or different location information. For example, assume that the transmitting UE transmits the MAC-CE twice, and assume that the transmitting UE initially transmits the MAC-CE in time slot "n" and transmits the MAC-CE a second time in time slot "n+L". In this case, the transmitting UE can configure the location information it transmits in time slot "n" to be the same as the location information transmitted in time slot "n+L". That is, (x, y) can be transmitted in time slot "n", and (x, y) can also be transmitted in time slot "n+L". If the moving speed of the transmitting UE is equal to or lower than or lower than a specific value (i.e., when the moving speed is not high), if the value "L" is equal to or less than or less than a specific value, or if both conditions are met, this can be applied. For example, assuming that the moving speed of the transmitting UE is 60 km / h, the transmitting UE can move 17 meters per second (i.e., the transmitting UE can move 17 centimeters in 10 ms). That is, there may be no significant difference between the location coordinates of the first transmission performed by the transmitting UE and the location coordinates of the second transmission performed by the transmitting UE. Therefore, if the speed of the transmitting UE is equal to or lower than or lower than a specific value, the transmitting UE may not need to frequently estimate its location to transmit its coordinates to the MAC-CE. In this case, the same location information can be included in the MAC-CEs transmitted by the transmitting UE for the first and second times. The above example can also be applied even when the MAC-CE is transmitted three or more times.

[0192] If the moving speed of the transmitting UE is equal to or higher than or higher than a specific value (i.e., if the moving speed is high), if the value "L" is equal to or higher than or higher than a specific value, or if both of the above conditions are met, the transmitting UE can update its location coordinates and transmit the location coordinates via the MAC-CE. For example, assuming that the moving speed of the transmitting UE is 120 km / h, the transmitting UE can move 33 meters per second (i.e., the transmitting UE can move 33 centimeters in 10 ms). If the value L is very large (e.g., 1000 ms = 1 second), there may be a large difference between the location coordinates (x, y) of the transmitting UE initially transmitted by the transmitting UE itself and the location coordinates (x1, y1) transmitted by the transmitting UE a second time. Therefore, in order to accurately measure the distance between the transmitting UE and the receiving UE, the transmitting UE can update its location coordinates and transmit the location coordinates via the MAC-CE.

[0193] Alternatively, the transmitting UE may calculate the difference between its previous position coordinates and its current position coordinates, rather than determining the conditions for the speed and / or value "L" of the transmitting UE, to determine whether to transmit the same position coordinates or updated position coordinates.

[0194] As Figure 13 shown in (a) of Figure 13 , a transmitting UE that has transmitted (x, y) via MAC-CE in time slot "n" may transmit, via SCI, the offset information between the coordinates (x, y) and the coordinates (x1, y1) in time slot "n+K". Alternatively, as

[0195] shown in (b) of Figure 13 , a transmitting UE that has transmitted (x, y) via MAC-CE in time slot "n" may transmit, via MAC-CE, the offset information between the coordinates (x, y) and the coordinates (x1, y1) in time slot "n+K". If distance-based HARQ operation is configured or activated and the transmitting UE transmits sidelink data, the offset value included in the SCI or MAC-CE may always be included in the SCI or MAC-CE information. Alternatively, the transmitting UE may consider the moving speed of the transmitting UE itself, the value "K", or both conditions to determine whether to transmit the offset information sent via SCI or MAC-CE. That is, if the position coordinates (x, y) transmitted by the transmitting UE via MAC-CE in time slot "n" and the position coordinates in time slot "n+K" have a value equal to or less than a specific value or have a value less than a specific value, the transmitting UE may not include the offset information in the SCI (or the field corresponding to the offset information in the SCI may be set to 0). Similarly, if the position coordinates (x, y) transmitted by the transmitting UE via MAC-CE in time slot "n" and the position coordinates in time slot "n+K" have a value equal to or less than a specific value or less than a specific value, the transmitting UE may not include the offset information in the MAC-CE. If the position information or offset information of the transmitting UE is not included in the SCI or MAC CE, the receiving UE may determine the position of the transmitting UE based on the position information of the previously received MAC CE.

[0195] The receiving UE that has received the location coordinates from the transmitting UE via MAC-CE in time slot "n" needs to know that the offset information of the coordinates of the transmitting UE will be sent via SCI or MAC-CE in time slot "n+K". The value of "K" can use the value configured by the base station, a pre-configured value, or a fixed value. If the receiving UE has received the offset information of the coordinates of the transmitting UE via SCI or MAC-CE in time slot "n+K", but fails to receive the coordinates of the transmitting UE via MAC-CE in time slot "n" (i.e., if the receiving UE fails to receive the MAC-CE or the decoding fails), the receiving UE may not send HARQ feedback to the transmitting UE. In this case, the receiving UE may send information for requesting location information to the transmitting UE. If the receiving UE cannot determine the location coordinate information of the transmitting UE, the receiving UE may check the distance between the transmitting UE and itself or determine the positional relationship with the transmitting UE based on the area information based on the area identifier, and may perform a distance-based HARQ feedback operation.

[0196] In Figure 13 the embodiment of, it has been described that the offset information is provided via SCI or MAC CE in time slot n+K, but the coordinate information of the transmitting UE may also be sent instead of the offset information. For example, if the offset value cannot be displayed in the offset field due to the magnitude of the offset value, and if it is determined that the previously received coordinate information of the transmitting UE is invalid after the lapse of time K, the coordinate information of the transmitting UE may be sent.

[0197] Figure 14 FIG. shows another example for transmitting the location information of the transmitting UE according to an embodiment of the present disclosure.

[0198] Figure 14Shows the case of frame synchronization between a sidelink transmitting UE and a sidelink receiving UE that perform multicast communication within the same group. More specifically, a sidelink UE (located in a single-hop from the base station) that directly selects the base station as the sidelink synchronization source or a sidelink UE (located in a two-hop from the base station and synchronized with the synchronization signal of another UE synchronized with the base station) that indirectly selects the base station as the sidelink synchronization source can use the system frame number (SFN) of the base station for synchronization. For example, the base station can configure the starting point of the sidelink resource pool for the sidelink UE via a time slot offset based on the base station system frame number 0. For this purpose, all sidelink transmitting UEs and sidelink receiving UEs in the base station should synchronize using the system frame number of the base station (i.e., the system frame number 0 considered by the base station is the same as the system frame number 0 considered by the sidelink transmitting UE and the sidelink receiving UE). Sidelink UEs (located in a single-hop from GNSS) that directly select the Global Navigation Satellite System (GNSS) as the sidelink synchronization signal source, or sidelink UEs (located in a two-hop from GNSS and synchronized with the synchronization signal of another UE directly synchronized with GNSS) that indirectly select GNSS as the sidelink synchronization signal source, can perform frame synchronization using the direct frame number (DFN) via the synchronization signal of GNSS. That is, UEs that have selected GNSS as the sidelink synchronization signal source can match the DFN therebetween. Finally, sidelink UEs (located in a two-hop from S-SSB) that directly select the sidelink synchronization signal block (S-SSB) transmitted by the UE as the sidelink synchronization signal source, or sidelink UEs (located in a two-hop from S-SSB and synchronized with the synchronization signal of another UE directly synchronized with the S-SSB transmitting UE) that indirectly select S-SSB as the sidelink synchronization signal source, can perform frame synchronization using the direct frame number (DFN) via S-SSB. That is, UEs that have selected the S-SSB transmitted by the UE as the sidelink synchronization signal source can match the DFN therebetween.

[0199] Regarding which synchronization signal to prioritize among the synchronization signal of the base station, the synchronization signal of GNSS, and the S-SSB transmitted by the UE during sidelink synchronization, rules configured by the base station, pre-configured rules, or predefined rules can be followed. The transmitting UE and the receiving UE performing sidelink multicast communication can match the SFN or DFN through these rules.

[0200] Under this assumption, as Figure 14 shown, the transmitting UE can send a MAC-CE including its own coordinates (x, y) to the receiving UE via the PSSCH at least once within the SFN or DFN period. Based on this, as Figure 13 shown, it is necessary to define the time relationship between the MAC-CE through which the location coordinates (x, y) are transmitted and the SCI or MAC-CE of the offset through which the location information is transmitted.

[0201] More specifically, after [x] ms, [y] time slots, or [z] symbols from the time point when the MAC-CE for transmitting the location information of the transmitting UE is transmitted, the transmitting UE needs to transmit an SCI or a MAC-CE, and the SCI or the MAC-CE includes an offset value of the location information of the transmitting UE itself. The receiving UE that has received the SCI or the MAC-CE including the offset value of the location information of the transmitting UE may assume that the transmitting UE has transmitted the location information by the MAC-CE before [x] ms, [y] time slots, or [z] symbols from the receiving time point based on the offset value.

[0202] For example, as Figure 14 shown, the transmitting UE may transmit its location coordinates (x, y) to the receiving UE via the MAC-CE within one SFN or DFN cycle. The MAC-CE including (x, y) of the transmitting UE may be transmitted at least once during a predetermined time period after slot Z1 of SFN 0 or DFN 0 (or after slot Z2 of the slot that initiates the sidelink resource within the SFN / DFN cycle) in the SFN or DFN cycle. That is, the transmitting UE may transmit the MAC-CE including (x, y) of the transmitting UE itself at a time configured by the base station, a pre-configured time, or a fixed time after slot Z1 of SFN 0 or DFN 0 within the SFN or DFN cycle. Also, for example, the transmitting UE may transmit the MAC-CE including (x, y) of the transmitting UE itself at a time configured by the base station, a pre-configured time, or a fixed time after slot Z2 of the slot that initiates the sidelink resource within the SFN / DFN cycle. In the above example, it is not excluded that Z1 = Z2 = 0. Here, the values of Z1 and Z2 may be configured by the base station, may be pre-configured, or may be fixed values.

[0203] The transmitting UE can transmit at a time configured by the base station, a pre-configured time, or a fixed time within the SFN or DFN cycle. The number of MAC-CE transmissions can be more than once. If the number of MAC-CE transmissions is two or more times, the interval between MAC-CE transmissions can or may not be constant. If the transmission interval is constant, the transmission interval can be configured by the base station or can be pre-configured. If the MAC-CE is transmitted two or more times, the MAC-CE can transmit the same location information or different location information. For example, assume that the transmitting UE transmits the MAC-CE twice, and assume that the transmitting UE initially transmits the MAC-CE in time slot "n" and transmits it a second time in time slot "n+L". In this case, the transmitting UE can configure the location information it transmits in time slot "n" to be the same as the location information transmitted in time slot "n+L". That is, (x, y) can be transmitted in time slot "n", and (x, y) can also be transmitted in time slot "n+L". If the moving speed of the transmitting UE is equal to or lower than or lower than a specific value (i.e., when the moving speed is not high), if the value "L" is equal to or less than or less than a specific value, or if both conditions are met, this can be applied. For example, assuming the moving speed of the transmitting UE is 60 km / h, the transmitting UE can move 17 meters per second (i.e., the transmitting UE can move 17 centimeters in 10 ms). That is, there may be no significant difference between the position coordinates of the first transmission performed by the transmitting UE and the position coordinates of the second transmission performed by the transmitting UE. Therefore, if the speed of the transmitting UE is equal to or lower than or lower than a specific value, the transmitting UE may not need to frequently estimate its position to send its coordinates to the MAC-CE. In this case, the same location information can be included in the MAC-CEs transmitted by the transmitting UE for the first and second times. The above example can also be applied even when the MAC-CE is transmitted three or more times.

[0204] If the moving speed of the transmitting UE is equal to or higher than or higher than a specific value (i.e., if the moving speed is high), if the value "L" is equal to or higher than or higher than a specific value, or if both of the above conditions are met, the transmitting UE can update its position coordinates and transmit the position coordinates via the MAC-CE. For example, assuming the moving speed of the transmitting UE is 120 km / h, the transmitting UE can move 33 meters per second (i.e., the transmitting UE can move 33 centimeters in 10 ms). If the value L is very large (e.g., 1000 ms = 1 second), there may be a large difference between the position coordinates (x, y) of the transmitting UE initially transmitted by the transmitting UE itself and the position coordinates (x1, y1) transmitted by the transmitting UE a second time. Therefore, to facilitate accurate measurement of the distance between the transmitting UE and the receiving UE, the transmitting UE can update its position coordinates and transmit the position coordinates via the MAC-CE.

[0205] For another example, instead of determining the speed of the transmitting UE and / or the condition of the value "L", the transmitting UE may calculate the difference between its previous position coordinates and current position coordinates, so as to determine whether to transmit the same position coordinates or updated position coordinates.

[0206] For another example, when transmitting sidelink data, the transmitting UE may always transmit its coordinates via MAC-CE. The coordinate information may be the above (x, y) (i.e., the initial position coordinates), or may be the coordinates at the time of transmitting the current MAC-CE.

[0207] As Figure 13 shown, the transmitting UE that has transmitted (x, y) via MAC-CE in time slot "n" may transmit the offset information of the coordinates (x, y) and the coordinates (x1, y1) via SCI or MAC-CE in time slot "n+K". If distance-based HARQ operation is configured or activated and the transmitting UE transmits sidelink data, the offset value included in the SCI or MAC-CE may always be included in the SCI or MAC-CE information.

[0208] For another example, the transmitting UE may consider the moving speed of the transmitting UE itself, the value "K", or these two conditions to determine whether to transmit the offset information transmitted via SCI or MAC-CE. That is to say, if the position coordinates (x, y) transmitted by the transmitting UE via MAC-CE in time slot "n" and the position coordinates in time slot "n+K" have a value equal to or less than a specific value or have a value less than a specific value, the transmitting UE may not include the offset information in the SCI (or the field corresponding to the offset information in the SCI may be set to 0). Similarly, if the position coordinates (x, y) transmitted by the transmitting UE via MAC-CE in time slot "n" and the position coordinates in time slot "n+K" have a value equal to or less than a specific value or less than a specific value, the transmitting UE may not include the offset information in the MAC-CE. If the position information or offset information of the transmitting UE is not included in the SCI or MAC CE, the receiving UE may determine the position of the transmitting UE based on the position information of the previously received MAC CE.

[0209] The receiving UE that has received the location coordinates from the transmitting UE via MAC-CE in time slot "n" needs to know that the offset information of the coordinates of the transmitting UE will be sent via SCI or MAC-CE in time slot "n+K". The value of "K" can use the value configured by the base station, a pre-configured value, or a fixed value. If the receiving UE has received the offset information of the coordinates of the transmitting UE via SCI or MAC-CE in time slot "n+K", but cannot receive the coordinates of the transmitting UE via MAC-CE in time slot "n" (i.e., if the receiving UE fails to receive the MAC-CE or the decoding fails), the receiving UE may not send HARQ feedback to the transmitting UE. In this case, the receiving UE may send information for requesting location information to the transmitting UE. If the receiving UE cannot determine the location coordinate information of the transmitting UE, the receiving UE may check the distance between the transmitting UE and itself based on the area information based on the area identifier, or determine the positional relationship with the transmitting UE, and may perform a distance-based HARQ feedback operation.

[0210] For example, if the period of the SFN or DFN is changed in Figure 14 , the transmitting UE may update the coordinates (x, y) that it sent latest in the previous SFN or DFN period, and may send new coordinates (x', y') to the receiving UE via MAC-CE. The time slot, the number of transmissions, and the transmission time for sending the new coordinates (x', y') may be the same as the above method. That is, the operations in the SFN or DFN period may be equally applied to subsequent SFN or DFN periods.

[0211] Figure 15 is a diagram showing the structure of a transmitting UE according to an embodiment of the present disclosure.

[0212] Referring to Figure 15 , the transmitting UE 1500 in the present disclosure may include a transceiver 1510, a controller 1520, and a storage unit 1530. The transceiver 1510 may send signals to the base station or another UE and receive signals from the base station or another UE. The signals may include synchronization signals, reference signals, control information, and data. To this end, the transceiver 1510 may include an RF transmitter configured to perform up-conversion and amplify the frequency of the transmitted signal, an RF receiver configured to perform low-noise amplification of the received signal and perform down-conversion, etc. In addition, the transceiver 1510 may receive signals via a wireless channel, output the signals to the controller 1520, and transmit the signals output from the controller 1520 via the wireless channel. The controller 1520 may control a series of processes so that the transmitting UE 1500 can perform operations according to embodiments of the present disclosure. The controller 1520 may include at least one processor.

[0213] Figure 16It is a diagram showing the structure of a receiving UE according to an embodiment of the present disclosure.

[0214] Reference Figure 16 , the receiving UE 1600 in the present disclosure may include a transceiver 1610, a controller 1620, and a storage unit 1630. The transceiver 1610 may send signals to a base station or another UE and receive signals from a base station or another UE. The signals may include synchronization signals, reference signals, control information, and data. To this end, the transceiver 1610 may include an RF transmitter configured to perform up-conversion and amplify the frequency of the transmitted signal, an RF receiver configured to perform low-noise amplification of the received signal and perform down-conversion, and the like. In addition, the transceiver 1610 may receive signals via a wireless channel, output the signals to the controller 1620, and transmit the signals output from the controller 1620 via the wireless channel. According to an embodiment of the present disclosure, the controller 1620 may control a series of processes so that the receiving UE can perform operations. The controller 1620 may include at least one processor.

[0215] Figure 17 It is a diagram showing the structure of a base station according to an embodiment of the present disclosure.

[0216] Reference Figure 17 , the base station 1700 of the present disclosure may include a transceiver 1710, a controller 1720, and a storage device 1730. The transceiver 1710 may send signals to a base station or another UE and receive signals from a base station or another UE. The signals may include synchronization signals, reference signals, control information, and data. To this end, the transceiver 1710 may include an RF transmitter configured to perform up-conversion and amplify the frequency of the transmitted signal, an RF receiver configured to perform low-noise amplification of the received signal and perform down-conversion, and the like. In addition, the transceiver 1710 may receive signals via a wireless channel, output the signals to the controller 1720, and transmit the signals output from the controller 1720 via the wireless channel. The controller 1720 may control a series of processes so that the UE can perform operations according to an embodiment of the present disclosure. The controller 1720 may include at least one processor.

[0217] In the above detailed embodiments of the present disclosure, according to the presented detailed embodiments, the elements included in the present disclosure are expressed in singular or plural forms. However, for ease of description, the singular or plural form is appropriately selected according to the presented situation, and the present disclosure is not limited to the elements expressed in singular or plural forms. Therefore, elements expressed in plural may also include a single element, or elements expressed in singular may also include multiple elements.

[0218] Although the present disclosure has been described with various embodiments, those skilled in the art can envision various changes and modifications. The present disclosure is intended to cover such changes and modifications that fall within the scope of the appended claims.

Claims

1. A method performed by a first terminal in a wireless communication system, the method comprising: Obtain resource pool information associated with a sidelink, where the resource pool information includes information about a period and information about resource blocks (RBs) for a physical sidelink feedback channel (PSFCH); Transmit sidelink control information (SCI) associated with sidelink data, where the SCI includes a region identifier (ID) of the first terminal, information about a range requirement, a first part of a destination ID of a second terminal, and an indicator indicating enabling of hybrid automatic repeat request (HARQ); Transmit the sidelink data on a physical sidelink shared channel (PSSCH) based on the SCI, where the sidelink data includes a second part of the destination ID of the second terminal; And Receive, from the second terminal, feedback information for negative acknowledgment associated with the sidelink data based on the information about the period and the information about the RBs when a distance between the first terminal and the second terminal is less than or equal to the range requirement, where the distance between the first terminal and the second terminal is identified based on a central position of a region indicated by the region ID and a position of the second terminal.

2. A method performed by a second terminal in a wireless communication system, the method comprising: Obtain resource pool information associated with a sidelink, where the resource pool information includes information about a period and information about resource blocks (RBs) for a physical sidelink feedback channel (PSFCH); Receive, from a first terminal, sidelink control information (SCI) associated with sidelink data, where the SCI includes a region identifier (ID) of the first terminal, information about a range requirement, a first part of a destination ID of a second terminal, and an indicator indicating enabling of hybrid automatic repeat request (HARQ); Receive the sidelink data from the first terminal on a physical sidelink shared channel (PSSCH) based on the SCI, where the sidelink data includes a second part of the destination ID of the second terminal; and, Transmit, to the first terminal, feedback information for negative acknowledgment associated with the sidelink data based on the information about the period and the information about the RBs when a distance between the first terminal and the second terminal is less than or equal to the range requirement, where the distance between the first terminal and the second terminal is identified based on a central position of a region indicated by the region ID and a position of the second terminal.

3. A first terminal in a wireless communication system, the first terminal comprising: A transceiver; And A controller configured to: Obtain resource pool information associated with a sidelink, where the resource pool information includes information about a period and information about resource blocks (RBs) for a physical sidelink feedback channel (PSFCH), Transmit, via the transceiver, sidelink control information (SCI) associated with sidelink data, where the SCI includes a region identifier (ID) of the first terminal, information about a range requirement, a first part of a destination ID of a second terminal, and an indicator indicating enabling of hybrid automatic repeat request (HARQ), Transmit, via the transceiver, the sidelink data on a physical sidelink shared channel (PSSCH) based on the SCI, where the sidelink data includes a second part of the destination ID of the second terminal, and, When the distance between the first terminal and the second terminal is less than or equal to the range requirement, based on the information about the period and the information about the RB, receive, via the transceiver, feedback information for negative acknowledgment associated with the sidelink data from the second terminal. Wherein, the distance between the first terminal and the second terminal is identified based on the central position of the area indicated by the area ID and the position of the second terminal.

4. A second terminal in a wireless communication system, the second terminal comprising: Transceiver; And A controller configured to: Obtain resource pool information associated with the sidelink, the resource pool information including information about a period and information about a resource block RB for a physical sidelink feedback channel PSFCH. Receive, via the transceiver, sidelink control information SCI associated with sidelink data from a first terminal, the SCI including an area identifier ID of the first terminal, information about a range requirement, a first part of a destination ID of a second terminal, and an indicator indicating enabling of hybrid automatic repeat request HARQ. Receive, via the transceiver, the sidelink data from the first terminal on a physical sidelink shared channel PSSCH based on the SCI, the sidelink data including a second part of the destination ID of the second terminal, and When the distance between the first terminal and the second terminal is less than or equal to the range requirement, send, via the transceiver, feedback information for negative acknowledgment associated with the sidelink data to the first terminal based on the information about the period and the information about the RB. Wherein, the distance between the first terminal and the second terminal is identified based on the central position of the area indicated by the area ID and the position of the second terminal.

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